Aquatic Invertebrates of Montana

Tubifex Ecology

• 1996. Timur, G., M. Timur, I.I. Turna, A. Kubilay and R. Ikiz. Tubificid culture. Turkish Journal of Zoology 20(1): 99-101. (Turkish)

  Abstract: Oligochaeta worm Tubifex sp., one of the best alive food for aquarium fish, has been cultured in the still water system. The worms were grown on three different substrates. The first substrate contained 50% fresh cow manure. 25% lake sand, and 25% garden soil. The second substrate contained 75% fresh cow manure and 25% lake sand. The third substrate contained 75% fresh cow manure and 25% garden soil. Growth and fecundity were observed in the three substrates. However, the highest growth rate, cocoon number and fecundity were found with the substratum containing 75% fresh cow manure and 25% garden soil.

• 1996. Sarkka, J. Meiofauna of the profundal zone of the northern part of Lake Ladoga as an indicator of pollution. Hydrobiologia 322(1-3): 29-38.

  Abstract: Benthic meiofauna was sampled at 19 stations, mainly in the northern part of Lake Ladoga, from depths between 13 and 199 m and from types of environment ranging from sheltered areas near pollution sources to less polluted open areas. About 80 taxa were identified, of these 70 to the species level. The greatest numbers of species were oligochaetes (24 species) and harpacticoids (8 species). Certain quantitative ratios of meiofauna were shown to be correlated with environmental data. The species of the oligochaete families Lumbriculidae and Aeolosomatidae and the harpacticoids as a collective group, excluding Canthocamptus staphylinus, were most clearly confined to the less eutrophied environments. The oligochaete species Amphichaeta leydigii, Dero digitata and Tubifex tubifex, the resting stages of Cyclopinae, and Eucyclops serrulatus among the Eucyclopinae were most clearly concentrated in the eutrophicated or polluted environments. The groups of Naididae, Cladocera and Eucyclopinae did not have much value as indicators. Shannon diversity index correlated positively with the total phosphorus content of the water, and number of species decreased with increasing depth. In general, it seems that the pollution tolerance of the meiofauna in a very large lake such as Lake Ladoga is high, presumably due to the effective mixing of water masses.

• 1995. Wilner, M.L. Some data of the zonation of the oligochaeta on the intertidal zone of Kandalaksha and Onega Gulfs of the White Sea. Vestnik Sankt-Peterburgskogo Universiteta Seriya 3 Biologiya 0(3): 9-13, 128. (Russian)

  Abstract: Oligochaets of 3 families were found at the intertidal zone of, Kandalaksha and Onega gulfs of White sea. The pattern of horizontal distribution of populations at intertidal zone depends on soil structure and duration of drying. Paranais litoralis (Naididae) is the most common species of the middle intertidal zone; Clitellio arenarius and Tubifex costatus (Tubificidae) prefer the same zone on mudsandy ground and the lower one on sandy ground; Tubificoides benedeni (Tubificidae) occurs also at the lower zone but prefers muddy ground. The Enchytraeidae is the most common among them. Members of this family are the only oligochaets inhabiting wrack beds of the upper intertidal zone, their density being especially high there (2 orders over that in the middle and the lower zones).

• 1995. Yu, K.C, S.T. Ho, J.K. Chang and S.D. Lai. Multivariate correlation of water quality, sediment and benthic bio-community components in Ell-Renn river system, Taiwan. Water Air and Soil Pollution 84(1-2): 31-49.

  Abstract: The distribution and correlation of benthic bio-community, water and sediment pollutants were evaluated with multivariate analysis from data collected over six samplings at 12 sites in the Ell-Ren river system, Taiwan. A total of 41 benthic algae species, 8 aquatic insect species and 2 annelid species were collected. On the basis of both principal component and correlation matrix analyses, we defined six water and sediment pollutant components to reveal common behaviour. Metrioenemus sp., Tubifex sp., Bacillariophyceae and Cyanophyceae could tolerate the environment at highly polluted sites. Caenis sp., Rhithrogena sp. and Baetis sp. preferred sites that were aerobic, and their populations were negatively correlated (52-56%) with detrital heavy metals in sediment. The population of benthic algae was positively variated with lead of the "bound to organic matters and sulphides" fraction, but negatively with copper in the detrital pattern. Results suggested that benthic bio-community demonstrated measurable relationships with water and sediment pollutants in Ell-Ren river system, and could be used as indicators to assess the water quality of river over a longer period.

• 1995. Seaby, R.M.H., A.J. Martin and J.O. Young. The reaction time of leech and triclad species to crushed prey and the significance of this for their coexistence in British lakes. Freshwater Biology 34(1): 21-28.

  Abstract: Three species of leeches, Erpobdella octoculata, Glossiphonia complanata and Helobdella stagnalis, and four species of triclads, Polycelis nigra, P. tenuis, Dugesia polychroa and Dendrocoelum lacteum, commonly coexist on stony shores in productive British lakes. All species are food limited and there is much overlap in their diet. For both leech and triclad communities, coexistence of species is through the occurrence of food refuges. Leeches are more successful than triclads at capturing live prey, whereas both groups feed on damaged prey, comprising incapacitated, live or dead animals that are leaking body fluids. If triclads are better than leeches at exploiting damaged prey, this could be a mechanism for their coexistence. Laboratory experiments investigated the comparative speeds at which leeches and triclads responded to crushed prey. Young and adult predators were offered a crushed specimen of the oligochaete Tubifex tubifex, the snail Lymnaea peregra, the crustacean Asellus aquaticus or the chironomid Chironomus sp., and their reaction times recorded. These four prey groups constitute the main diet of the predators in the field. Only D. polychroa and D. lacteum showed a significantly different reaction time between young and adults to crushed prey, and the reason for this is unclear. All predators, except H. stagnalis and D. polychroa, showed a difference in reaction time to the four types of prey, presumably a consequence of differences in both the 'quality' and 'concentration' of the different prey fluids, and there were some differences between predators in their speed of reaction to the same prey type. The following sequence, from fastest to slowest, in general reaction time to prey was obtained: E. octoculata, D. polychroa, P. tenuis, D. lacteum, P. nigra, H. stagnalis and G. complanata. The location of the damaged food by the predators can be explained partly in terms of their foraging behaviour, with E. octoculata, D. polychroa and P. tenuis exhibiting a more seek-out strategy than other species which have a more sit-and-wait behaviour, and partly on the level of sophistication of their chemosensory system used to detect leaked prey fluids. This system is highly developed in triclad species but poorly developed in leeches. In a second type of experiment in which prey, L. peregra, A. aquaticus or Chironomus sp., were offered at different time intervals after crushing to H. stagnalis and P. tenuis, few predators fed on food crushed for 24 h or longer, although a few leeches fed on Chironomus crushed for up to 72 h. It is concluded that coexistence of leech and triclad species on stony shores in lakes is assisted by partitioning of food on a damaged or live basis.

• 1995. Day, K.E., R.S. Kirby and T.B. Reynoldson. The Effect Of Manipulations Of Freshwater Sediments On Responses Of Benthic Invertebrates In Whole-Sediment Toxicity Tests. Environmental Toxicology and Chemistry 14(8): 1333-1343.

  Abstract: Manipulations of freshwater sediment were performed to remove indigenous organisms prior to conducting toxicity tests with three species of benthic invertebrates. The effects of these treatments on end points in bioassays were compared within and between two sediments, i.e., a "clean" sediment and a "contaminated" sediment. In addition, the effects of manipulations on the physicochemical structure of the two sediments and the presence of metals, Pahd, and Pcbs in the contaminated sediment were examined. The amphipod Hyalella azteca was most sensitive to the manipulations and had low survival in sediment that was sterilized. Growth (milligrams dry weight per individual) was affected by the presence of contaminants. Survival of Chironomus riparius was not affected by any manipulation but was reduced by contaminants as well as indigenous organisms. Growth of C. riparius was higher in autoclaved sediment but lower in sediment containing endemic tubificid worms. Production of young by Tubifex tubifex increased in sediment that was irradiated, possibly due to increased detrital material. Particle size distribution, metals, nutrients, and Pahs varied little as a function of manipulation; however, sieving of sediment through 250-mu-m mesh did reduce percent total organic carbon (Toc), percent loss on ignition (Loi), and concentrations of some Pcbs in either clean or contaminated sediment. Manipulation of sediments to remove endemic species should be determined on a caseby-case basis and is specific to the organisms used in toxicity tests.

• 1995. Day,K.E., B.J. Dutka, K.K. Kwan, N. Batista, T.B. Reynoldson and J.L. Metcalfe-Smith. Correlations between solid-phase microbial screening assays, whole-sediment toxicity tests with macroinvertebrates and in situ benthic community structure. Journal of Great Lakes Research 21(2): 192-206.

  Abstract: There have been few comparative assessments of the relative sensitivities of microorganisms in short-term (1 to 20 min.) screening bioassays and benthic invertebrates exposed for longer periods of time (10- to 28-d) to contaminated sediments. In this paper, the responses of four species of benthic invertebrates (Chironomus riparius, Hyalella azteca, Hexagenia spp., and Tubifex tubifex) and three microorganisms (Escherichia coli, Photobacterium phosphoreum, and Bacillus spp.) were compared using rank correlation (Spearman's r-s), for sediments collected from 46 nearshore sites ( lt 3 km) in the Laurentian Great Lakes. At a subset of sites (n = 27), data on the benthic invertebrate community structure were obtained and these sites were ranked and compared to the responses in each of the laboratory tests. The results indicate that two of the microbial screening tests, specifically, the Sediment-Chromotest, which measures inhibition of the inducible enzyme, beta-galactosidase, in E. coli, and the Microtox Solid-Phase Test (measures inhibition of bioluminescence), correlated with results from tests with invertebrates, particularly decreased survival of C. riparius (r-s = 0.545 and 0.463, respectively), reduced growth of H. azteca (r-s = 0.347 and 0.467, respectively) and Hexagenia (r-s = 0.307 and 0.385, respectively) and lower production of cocoons by T. tubifex (r-s = 0.347 and 0.416, respectively). In addition, reduced growth of C. riparius was positively correlated with reduced growth of the mayfly, Hexagenia spp. (r-s = 0.655), survival and growth of the amphipod, H. azteca (r-s = 0.416 and 0.570) and decreased production of cocoons (r-s = 0.703) or live young (r-s = 0.658) by T. tubifex. When information on the structure of the benthic invertebrate community was included as a subset of the data (n = 27), two microbial tests (Microtox Spt and Sediment-Chromotest) and several invertebrate tests (e.g., growth of C. riparius, H. azteca, and Hexagenia and reproduction by T. tubifex) were strongly correlated with a degradation of the benthic community composition.

• 1995. Keddy,C.J., J.C. Greene and M.A. Bonnell. Review of whole-organism bioassays: Soil, freshwater sediment, and freshwater assessment in Canada. Ecotoxicology and Environmental Safety 30(3): 221-251.

  Abstract: Whole organism bioassays for the assessment of soil, freshwater sediment, and freshwater quality were evaluated for their application in the assessment and remediation of contaminated sites in Canada under the National Contaminated Sites Remediation Program. Using 3 essential and 12 desirable methodological criteria, bioassays were categorized as currently usable, prototype, or under development. Based on further considerations related to bioassay application, a battery of usable screening and definitive tests was recommended (with suggestions for augmentation) for each medium. Of the 18 bioassays reviewed for soil quality assessment, 6 were usable, 5 were prototypes, and 7 were under development. Battery screening and definitive tests included 14-day Eisenia andrei survival, 120-hr lettuce and radish seedling emergence, and 72-hr Selenastrum capricornutum growth inhibition. Augmentation with the following bioassays was recommended: soil/ freshwater bacterial growth, arthropod reproduction, earthworm reproduction, and reproduction of other soil-dependent organisms. Of the 9 bioassays reviewed for freshwater sediment quality assessment, 1 was usable, 2 were prototypes, and 6 were under development. Three bioassays in the latter two groups were considered usable with the imminent completion of research underway. Screening tests selected included 10-day Chironomus tentans survival, 10-day Hyalella azteca survival, 10-day Hexagenia spp. survival, and 72-hr S. capricomutum growth inhibition. Definitive tests included screening tests, substituting 28-day H. azteca sexual maturation for 10-day survival. Augmentation with the following bioassays was recommended: sediment/freshwater bacterial test, 28-day Tubifex tubifex reproduction, and rooted aquatic plant growth. Of the 25 bioassays considered for freshwater quality assessment, 8 were usable, 7 were prototypes, and 10 were under development. Screening tests selected included 72-hr S. capricornutum growth inhibition; 48-hr Daphnia sp. survival, and 5- and 15-min Photobacterium phosphoreum bioluminescence. Definitive tests included first screening test, 7-day Ceriodaphnia dubia, 7-day fathead minnow larval survival, or 96-hr rainbow trout survival. Augmentation with the following bioassays was recommended: Brachionus calyciflorus 24-hr survival, 48-hr reproduction; freshwater bacterial growth; and aquatic vascular plant growth.

• 1994. Fargasova, A. Comparative study of plant growth hormone (herbicide) toxicity in various biological subjects. Ecotoxicology and Environmental Safety 29(3): 359-364.

  Abstract: Due to their widespread distribution and toxic nature, herbicides may have a serious impact on the environment and exert adverse effects on associated organisms. The present study was conducted to determine the acute toxicological effects of some plant growth hormones used as herbicides on four biological subjects and compare the subjects' sensitivity to individual testing substances. The herbicides 4-(indol-3-yl)acetic acid C-10H-9O-2N (Iaa), N-6-(beta-2-isopentenyl)adenosine (pi-indolylpropionic acid) C-11H-11O-2N (Ipa), 2,4-dichlorophenoxyacetic acid C-8H-6O-3Cl-2 (2,4-D), 4-chloro-2-methylphenoxyacetic acid C-9H-9O-3Cl (Mcpa), and 1,napthylacetic acid C-12H-10O-2 (Naa) were tested and the following biological subjects were used: Daphnia magna, Tubifex tubifex, Scenedesmus quadricauda, and seeds of Sinapis alba. For S. alba, the influence of herbicides on seed germination (G) and root growth inhibition (I) was observed. For T. tubifex, the tests lasted 96 hr, for D. magna 48 hr, for S. quadricauda 20 days, and for S. alba 72 hr. The rank order of toxicity of herbicides used for T. tubifex was Naa gt Iaa gt Ipa gt 2,4-D gt Mcpa; for D. magna. Naa gt Iaa gt Ipa gt Mcpa gt 2,4-D; for S. quadricauda. Iaa gt Ipa gt Naa gt Mcpa gt 2,4-D; for S. alba seed germination, Naa gt Ipa gt 2,4-D gt Mcpa gt Iaa; and for root growth inhibition. Naa gt 2,4-D gt Mcpa gt Iaa gt Ipa. When the sensitivity of tested organisms to individual herbicides was studied from Lc-50 and Ec-50 values, the following rank orders of sensitivity were obtained: for Iaa, it was S. alba (I) gt S. quadricauda gt T. tubifex gt D. magna gt S. alba (G); for 2,4-D, it was S. alba (I) gt S. quadricauda gt T. tubifex = S. alba (G) gt D. magna; for Mcpa, it was S. alba (I) gt S. quadricauda gt T. tubifex = D. magna = S. alba (G); for Ipa, it was S. alba (I) gt T. tubifex, S. quadricauda gt D. magna = S. alba (G); and for Naa, it was S. alba (I) gt S. quadricauda gt T. tubifex gt S. alba (G) gt D. magna.

• 1994. Cernakova,M. and E. Golis. Testing of the cytotoxic effects of sulfate pulp mill waste waters. Folia Microbiologica 39(4): 307-314.

  Abstract: The effect of 22 technological waste water samples and of some standards was tested on bacteria, fungi, chlorococcal algae, flagellata, plant cells, cells of Tubifex tubifex, hamster cells V79 and the fish Lebistes reticulatus. Of these 22 samples, some inhibition of cell life processes was displayed by the black liquor formed in the production of paper pulp and viscose pulp, by the waste solution produced during the preparation of bleaching agents for paper pulp and viscose pulp, and by the residual liquor after hypochlorite treatment of paper pulp.

• 1994. Van De Bund,W.J. W. Goedkoop and R.K. Johnson. Effects of deposit-feeder activity in bacterial production and abundance in profundal lake sediment. Journal of the North American Benthological Society 13(4): 532-539.

  Abstract: Effects of the amphipod Monoporeia affinis, the oligochaete Tubifex tubifex and the chironomid Chironomus riparius on the production ((3H)-thymidine incorporation) and abundance (acridine orange direct counts) of sediment bacteria were studied in a series of microcosm experiments. Measurements were performed on the visually distinct sediment zonation generated by oxygen penetration and influenced by deposit-feeder activity. All three species at higher densities caused an increase in the depth of the light-colored surficial sediment layer in the microcosms. Bacterial production in surficial sediment increased by factors as high as 3.2 times (Monoporeia experiment), 1.4 times (Tubifex experiment), and 4.4 times (Chironomus experiment) compared with controls. Physical disturbance of sediment through invertebrate activity was concluded to be the main causal mechanism for increases in bacterial production. Changes in bacterial abundance appeared to be zoobenthos species-specific, reflecting differences in feeding and/or foraging behavior of the animals. Bacterial abundance was negatively affected by mechanical stirring and by the activity of Tubifex tubifex, a subsurface deposit-feeder known to gain a large proportion of its energy demand from sediment bacteria. Monoporeia affinis and Chironomus riparius did not affect bacterial abundance; apparently their surficial feeding activity resulted in a compensation of bacterial losses. In subsurface sediment layers neither bacterial abundance nor production was affected by any of the three species.

• 1994. Fargasova, A. A comparative study of the toxicity and inhibitory effects of inorganic tin compounds on various biological subjects. Biologia (Bratislava) 49(3): 307-311.

  Abstract: The toxic and inhibitory effects of Sn-2+ (SnCl-2 cntdot 2H-2O) and Sn-4+ (Na2SnO-3) compounds were determined under standardized conditions on four biological subjects: Tubifex tubifex, Chironomus plumosus, Sinapis alba seeds and the alga Scenedesmus quadricauda. Observed were the mortality rates of Tubifex tubifex and Chironomus plumosus, the root growth inhibition of Sinapis alba seeds, and the inhibition of growth rates of Scenedesmus quadricauda. Of the bentic organisms, Chironomus plumosus was more sensitive (Lc50/96 h for Sn-2+ was 3.6 mg cntdot l-1 and for Sn-4+ 3.0 mg cntdot l-1) to both tested compounds than Tubifex tubifex (Lc50/96 h for Sn-2+ was 30.0 mg cntdot l-1 and for Sn-4+ 27.5 mg cntdot l-1). For both of these subjects, no differences between the toxic effects of Sn-2+ and Sn-4+ ions were observed. Sinapis alba seeds exhibited low sensitivity to Sn ions (Ec50/72 h for Sn-2+ was 281.2 mg cntdot l-1 and for Sn-4+ 416.9 mg cntdot l-1). Estimated Ec50 values were high, especially for the Sn-4+ ion. Root growth was more inhibited when Sn-2+ ion was applied. For Scenedesmus quadricauda, Sn-4+ ion also had lower inhibitory effects on growth rates than the Sn-2+ ion.

• 1994. Sabodash, V.M. A.Y. Shcherbukha, V.I. Monchenko, A.V. Kornyushin, V.M. Ermolenko, V.A. Kostyushin and V.I. Kryzhanovskii. Ecological expert assessment of the status of the fauna in the construction area of the Dniester pumped storage electric power plant. Vestnik Zoologii 0(1): 70-74.
• 1994. Fargasova, A. Comparative toxicity of five metals on various biological subjects. Bulletin of Environmental Contamination and Toxicology 53(2): 317-324.
• 1994. Reynoldson, T.B., K.E. Day, C. Clarke and D. Milani. Effect of indigenous animals on chronic end points in freshwater sediment toxicity tests. Environmental Toxicology and Chemistry 13(6): 973-977.

  Abstract: Sediment toxicity tests were conducted using three species of benthic invertebrates, Chironomus riparius, Hyalella azteca, and Hexagenia limbata, with various densities of the oligochaete worm Tubifex tubifex. It was shown that indigenous animals, simulated by the presence of Tubifex tubifex, did not affect survival of the test species (P gtoreq 0.05) but did reduce growth in all three test species and in two species at the lowest tested densities, equivalent to 1,460 worms per square meter. At densities of Tubifex tubifex equivalent to 20,000 m-2, the growth of Chironomus riparius was reduced by gt 90%, Hyalella azteca by gt 60%, and Hexagenia limbata by almost 50%. The densities of oligochaetes are equivalent to those found in many contaminated sites. Therefore, it is concluded that the presence of indigenous organisms can confound the interpretation of toxicity test results, based on chronic end points. It is recommended that removal of organisms be considered before toxicity tests are conducted with freshwater sediments from sites with large populations of benthic invertebrates, especially oligochaete worms.

• 1994. Bazzanti, M, M. Seminara and C. Tamorri. Depth distribution and relationships to the trophic state of sublittoral and profundal macrobenthos in Lake Vico (Central Italy). Limnologica 24(1): 13-21.

  Abstract: Sublittoral and profundal macroinvertebrates of mesotrophic Lake Vico (Central Italy) were studied in order to analyze their structural and functional feeding organization and to determine their depth distribution and relationships with the trophic state of the water. About 17000 organisms belonging to 49 taxa were collected during the study, the most abundant being Potamothrix heuscheri and Tubifex tubifex among of oligochaetes and Procladius, Tanytarsus and Micropsectra among chironomids. The results show a distinction between the sublittoral (10 m depth) and the profundal (20-40 m depth) fauna, characterized by the exclusive or more abundant occurrence of some taxa in each depth zone, by lower abundances of total fauna, oligochaetes and chironomids, collectors and shredders in the sublittoral than in the upper profundal (20 m), and by an appreciable presence of scrapers only in the sublittoral. The benthic assemblages are in agreement with the mesotrophic state revealed by chemical parameters of the water, being composed of both oligotrophic and eutrophic taxa. The values of both diversity and oligochaete/chironomid ratio confirm the mesotrophic state of the lake. Some taxa and benthic parameters that may be useful as monitors for detecting future trophic changes in the lake are indicated.

• 1994. Anlauf, A. Some characteristics of genetic variants of Tubifex tubifex (Muller, 1774) (Oligochaeta: Tubificidae) in laboratory cultures. Hydrobiologia 278(1-3): 1-6.

  Abstract: Genetic variants of the oligochaete Tubifex tubifex were identified with enzyme electrophoresis and subsequently reared in laboratory cultures. Three types are abundant in field populations. Individuals that show homozygotic bands of glucosephosphate-isomerase (Gpi) 22 together with isocitrate-dehydrogenase (Idh) 35 were labeled Type A. Type B is characterized by Gpi 23 together with Idh 11 and Type C is characterized by Gpi 11 with either Idh 34 or Idh 33. Initial results on freshweights of adults and cocoon production revealed differences between the two main types, A and B. In the same period, Type B reached higher weights and produced five times as many cocoons as Type A, whereas number of eggs per cocoon were not different between these Types. Type B also had the lowest mortality in 16-week experiments with changing temperatures.

• 1994. Pasteris, A., C. Bonacina and G. Bonomi Observations on cohorts of Tubifex tubifex cultured at different food levels, using cellulose substrate. Hydrobiologia 278(1-3): 315-320.

  Abstract: In order to clarify the relationship between food availability and population dynamics in aquatic oligochaetes, short term cultures and cohort cultures of Tubifex tubifex were reared using substrates with different food concentrations, obtained by mixing sand with different amounts of cellulose powder. In short term experiments, T. tubifex seemed capable of utilizing cellulose substrates for growth or egg production. Yet, in the cohort experiment, newly hatched worms could not grow on cellulose substrates. Survivorship, however, appears to be influenced by cellulose concentration giving an indication that this material, although inadequate, is somehow utilized.

• 1994. Reynoldson, T.B. A field test of a sediment bioassay with the oligochaete worm Tubifex tubifex (Muller, 1774). Hydrobiologia 278(1-3): 223-230.

  Abstract: A sediment toxicity test using reproduction in the tubificid oligochaete Tubifex tubifex was tested in 11 geographic locations in the Laurentian Great Lakes where sediments have previously been documented as being contaminated. Samples were taken from both potentially contaminated and "clean" sites in each of the 11 areas. Using test endpoints such as survival and growth, results from 72 samples were classified using cluster and ordination techniques. Six response groups were identified and four groups of toxic sites determined. Toxic effects ranged from mortality of adult worms to reduced reproduction. Using correlation and discriminant analysis there was good evidence that high concentrations of metals such as copper and lead were responsible for the observed effects at some sites.

• 1994. Milbrink, G. Oligochaetes and water pollution in two deep Norwegian lakes. Hydrobiologia 278(1-3): 213-222.

  Abstract: Analyses of the oligochaete fauna of two of the deepest lakes in Scandinavia - the Norwegian lakes Mjosa (450 m) and Tyrifjorden (295 m), revealed a totally different species composition in the deep profundal compared with the upper profundal - in contact with the nutrient-enriched epilimnion. In both lakes a pronounced thermal stratification develops in the summer, thus the epilimnion receiving gross organic pollution behaves differently from the profundal. The lakes are each effectively divided into two bodies of water with limited water exchange between them, i.e. one major oligotrophic body and one minor more nutrient-rich. Since the 1950s both lakes have been exposed to heavy pollution of various kinds. In Lake Mjosa in 1975 and 1976 unpleasant algal blooms of the blue-green alga Oscillatoria bornetii fa. tenuis occurred. Bottom samples obtained at the same time revealed that the deep central bottoms of the lake were totally dominated by oligotrophic oligochaete indicators, i.e. by Stylodrilus heringianus and Spirosperma ferox, while the fauna of the upper profundal in the vicinity of domestic and agricultural sewage outfalls, wood processing industries, etc. was dominated by Limnodrilus hoffmeisteri and Tubifex tubifex in great abundance, indicating enriched conditions. Several other species indicative of eutrophy, were absent, most of them belonging to the genus Potamothrix. A fairly similar situation exists in Lake Tyrifjorden, where, for instance, in the shallow bay of Steinsfjorden - heavily eutrophied by agricultural wastes - blooms of blue-green algae have caused problems from time to time. The same oligochaete communities as in Lake Mjosa distinguish the central oligotrophic bottoms from the regionally more enriched upper profundal. The likely reasons for an intact profundal oligochaete fauna are great volumes of oxygen-rich hypolimnic water of low temperature and a high bottom/lake surface area ratio.

• 1994. Casellato, S. and F. Caneva. Composition and distribution of bottom oligochaete fauna of a north Italian Eutrophic Lake (Lake Ledro). Hydrobiologia 278(1-3): 87-92.

  Abstract: The profundal macroinvertebrates, particularly the oligochaetes, of Lake Ledro (Trento, Italy), that has recently undergone eutrophication, were studied. A statistical approach of random sampling was used to study the distribution and abundance of the oligochaete species. The optimum sample number was calculated from a preliminary sample series. The oligochaete community was made up of five tubificid species, one naidid and one lumbriculid species that on average represents more than 80% of the macrobenthic community. Population density was correlated with depth and decreasing oxygen concentration. The role of Tubifex tubifex as a eutrophic, tolerant species was confirmed; and in fact it was the only species found (although at low density) in the deepest and anoxic zone. No comparable data are available for the lake prior to eutrophication, but these data will be valuable for future comparison once a remediation program for the lake has been implemented.

• 1994. Fargasova, A. Toxicity of metals on Daphnia magna and Tubifex tubifex. Ecotoxicology and Environmental Safety 27(2): 210-213.

  Abstract: The toxicity of Hg-2+ (HgCl-2), Cr-6+(1) ((Nh-4)-2CrO-4), Cr-6+(2) (CrO-3), Cd-2+ (CdCl-2 cntdot 2,5H-2O), Pb-2+ (Pb(Ch-3Coo)-2 cntdot 3H-2O), and As-5+ (Na-2HasO-4 cntdot 7H-2O) on the sensitivity and survival of Daphnia magna and Tubifex tubifex has been studied. All test metals were dissolved and determined under standardized conditions (dilution water, Bringmann and Kuehn, 1982) and 96 hr Lc-50 for T. tubifex and 48 hr Lc-50 for D. magna were compared in rank orders toxicity. For D. magna rank order toxicity was Hg-2+ gt Cr-6+ (2) gt Cd-2+ = Cr-6+ (1) gt Pb-2+ gt As-5+ and for T. tubifex it was Hg-2+ gt Cd-2+ gt Cr-6+(2) gt Cr-6(1) gt Pb-2+ gt As-5+. D. magna was a more sensitive organism than T. tubifex and its Lc-50 values for all metals were several times lower than Lc-50 values for T. tubifex. Correlation between toxicity of various metals and biological subjects may be useful in predicting toxicity to various biologically important organisms connected with food chains.

• 1994. Bremnes, T. and S.E. Sloreid. Oligochaetes of freshwater: Distribution in south Norway. Nina Utredning 0(56): 1-42.

  Abstract: The distribution of freshwater oligochaetes in South Norway is presented. Comments on the ecology, species characteristics, etc. are given for the individual species. Data are based on literature surveys, unpublished observations, and reviews of material made available by others. A total of 44 species has been observed in South Norway. Lumbriculus variegatus, Stylodrilus heringianus, Spirosperma ferox and Tubifex tubifex have the widest distribution. On the basis of own observations, the distribution of the species and knowledge about their ecological requirements, we describe oligochaete communities which can be expected to be found in different freshwater localities in Norway. Furthermore, a summary on the use of freshwater oligochaetes as indicator species of different environmental conditions is given. They have proved to be especially valuable as indicators of different trophic levels in lakes, and a short presentation on their usefulness in acidification studies is given.

• 1994. Martin, A.J. R.M.H. Seaby and J.O. Young. Does body size difference in the leeches Glossiphonia complanata (L.) and Helobdella stagnalis (L.) contribute to co-existence? Hydrobiologia 273(2): 67-75.

  Abstract: The effect of predator and prey body size on the feeding success of the British lake-dwelling leeches Glossiphonia complanata and Helobdella stagnalis was examined in the laboratory, and any involvement of size difference between the leeches in allowing coexistence in the field assessed. G. complanata breeds in advance of H. stagnalis and maintains a body size advantage throughout their annual life-cycle. In experiments, conducted at 14 degree C and a photoperiod of 16 hrs L: 8 hrs D, three size classes of leeches of each species were each exposed to each of three size classes of each of five prey species, viz. Tubifex sp., Chironomus sp. Asellus aquaticus Lymnaea peregra and Potamopyrgus jenkinsi. For each prey species, three different types of experiments were performed: one leech exposed to four prey individuals; four leeches of the same species with sixteen prey; and two leeches of each species with sixteen prey. In the first experiment, all sizes of G. complanata were capable of feeding on all sizes of the prey types offered: the same was true for H. stagnalis with exceptions of feeding on large A. aquaticus and large L. peregra. For both species, but especially for G. complanata, there was a trend within each size class of leech for decreasing proportions of fed leeches with increasing prey size, and within each size class of prey for an increasing proportion of fed leeches with increasing leech size; however, there were several exceptions to these trends. Both leeches fed extensively on Tubifex sp. but there were significant differences in the proportions feeding on other prey types; G. complanata fed more on A. aquaticus and the two snail species, and less on Chironomus, than H. stagnalis. The effect of increasing the number of leech individuals from one to four individuals, of the same or mixed species, had little effect on the proportion of leeches which had fed. It is concluded that large G. complanata will have access to large individuals of certain prey taxa denied H. stagnalis, which may lessen the intensity of interspecific competition.

• 1993. Ohtaka,A and T. Iwakuma. Redescription of Ophidonais serpentina (Muller, 1773) (Naididae, Oligochaeta) from Lake Yunoko, Central Japan, with record of the oligochaete composition in the lake. Japanese Journal of Limnology 54(4): 251-259.

  Abstract: A naidid oligochaete, Ophidonais serpentina (Muller, 1773) is redescribed based on specimens from Lake Yunoko, central Japan. This is the first record of this species from Pacific Asia. Among 1988 specimens, eleven species of oligochaetes were recorded from Lake Yunoko. Ophidonais serpentina was abundant in the littoral zone, but disappeared in the deeper profundal. Tubifex sp. and Limnodrilus spp. (L. hoffmeisteri and L. claparedianus) composed 86-100% of the oligochaete assemblage except at the central eastern inlet. The oligochaete densities were higher in the northern basin, accounting for several tens of thousands of individuals m-2 in the upper profundal.

• 1993. Lang,C. and O. Reymond. Trends in phytoplanktonic and zoobenthic communities after the decrease of phosphorus concentrations in Lake Joux. Revue Suisse de Zoologie 100(4): 907-912.

  Abstract: The eutrophic Lake Joux (Jura Mts., Switzerland) has been continuously colonized from 1980 to 1992 by dense populations of Oscillatoria rubescens, even after phosphorus concentrations began to decrease in 1986. At a depth of 25 m, biomass and abundance of chironomid larvae decreased between 1985 and 1992 whereas abundance of Chaoborus larvae increased. In addition, abundance of Tubifex tubifex increased in tubificid communities relatively to that of Limnodrilus hoffmeisteri. These trends are indicative of a deterioration of oxygen conditions in the profundal. They suggest that benthic communities will not recover from eutrophication as long as planktonic communities are dominated by Oscillatoria.

• 1993. Gee, J.H.R. and C.A. Duigan. The limnology of Lac d'Ifni (High Atlas Mountains, Morocco), an unusually productive mountain lake. Freshwater Biology 30(3): 447-462.

  Abstract: 1. Lac d'-Ifni (surface area 30 ha, z-max 60 m, altitude 2300 m) lies in a catchment comprised of Precambrian igneous rocks in the High Atlas Mountains of Morocco. Previously described as a typical oligotrophic lake, it was also reported to have a warm layer at the base of the hypolimnion which was ascribed to phreatic water supply and drainage. 2. Visits to the lake made in May/June and September 1990 showed strong thermal stratification but not hypolimnial warm layer. Drainage from the lake is subterranean, through a natural rubble dam, and the water level dropped by at least 7 m through the summer. The flushing rate is about 0.6 year-1. 3. The upper part of the metalimnion and the lower epilimnion were strongly supersaturated with oxygen in June, and there was a pH gradient from 7 to 10.5 between the hypolimnion and the epilimnion. These features were less marked in September when planktonic gross primary productivity was estimated to be about 145 mg C m-2 h-1. In September the hypolimnion was 38% saturated with oxygen; the areal hypolimnetic oxygen deficit between June and September was 0.073 mg O-2 cm-2 day-1. Total dissolved phosphate concentrations were 7-14 mu-g l-1. 4. The open water faunal assemblage consisted of Brachionus calyciflorus and Filinia longiseta (Rotifera), Cyclops abyssorum (Copepoda), and stunted Salmo trutta (Pisces). Trout diets were comprised principally of adult copepoda and copepodites, which showed diurnal vertical migration, and of algal material apparently scraped from rock surfaces. The dry biomass density of Cyclops was at least 2 g m-2 in June and at least 4.1 g m-2 in September. 5. Tubifex tubifex (Oligochaeta) dominated the benthos below depths of 40 m. Mean dry biomass density was 2.8 g m-2, but ranged from 0.6-8.1 g m-2 between samples. About 50% of the lake bottom is below 40 m depth. 6. The persistent oxygen supersaturation of the euphotic zone, the field estimate of primary productivity, the hypolimnetic oxygen deficit, the biomass of zooplankton and the benthic biomass together indicate that Lac d'Ifni is an unusually productive mountain lake. This high level of productivity may be sustained by nutrient addition through contamination by dust originating outside the catchment, aided by efficient nutrient recycling in the euphotic zone.

• 1993. Milbrink, G. Evidence for mutualistic interactions in freshwater oligochaete communities. Oikos 68(2): 317-322.

  Abstract: Mutualistic interactions between closely related invertebrate species are not much known from the literature and evidence for their existence are rare. Here I present evidence for mutualistic interactions - "reciprocal facilitation" - between oligochaete species forming characteristic species associations in freshwater. These associations are the likely results of species-specific feeding on bacteria colonizing the fecal pellets of the component species. In laboratory tests with the species association Potamothrix moldaviensis and Tubifex tubifex each species grows significantly better when fed upon the fecal pellets of the other species, suggesting mutual advantages. Laboratory results are in good agreement with field data from Lake Malaren, Sweden, indicating higher total abundance of worms in associations containing species of the genus Potamothrix, originating in the Ponto-Caspian region and gradually expanding front the south-east over Europe. These results suggest that facultative mutualisms, also in the temperate zone, may be more common thin generally believed.

• 1993. Gregory, R.S. and T.G. Northcote. Surface, planktonic, and benthic foraging by juvenile chinook salmon (Oncorhynchus tshawytscha) in turbid laboratory conditions. Canadian Journal of Fisheries and Aquatic Sciences 50(2): 233-240.

  Abstract: We investigated the effect of turbidity on the foraging behaviour of juvenile chinook salmon (Oncorhynchus tshawytscha) in the laboratory. We assessed visual ability by measuring the reaction distance of juvenile chinook to planktonic adult Artemia prey. Chinook exhibited a log-linear decline in reaction distance with increasing turbidity. These results were similar to those obtained by workers for other species. We also determined the effect of turbidity on the foraging rate of juvenile chinook for surface (Drosophila), planktonic (Artemia), and benthic (Tubifex) prey across a range of turbidity levels ( lt 1, 18, 35, 70, 150, 370, 810 Ntu). Foraging rates were reduced at higher turbidities for all three prey. However, for surface and benthic prey, foraging rates were also low in clear water, while highest rates were attained at intermediate turbidity levels (35-150 Ntu). We suggest that increased feeding rate in turbid conditions reflects a reduced potential risk to predators.

• 1993. Scholz, T. On the development of Khawia baltica Szidat, 1942 (Cestoda: Lytocestidae), a parasite of tench, Tinca tinca (L.). Folia Parasitologica (Prague) 40(2): 99-103.

  Abstract: The development of the tapeworm Khawia baltica Szidat, 1942 (Cestoda: Caryophyllidea), parasitizing tench, Tinca tinca (L.), was studied under laboratory conditions. The rate of oncospheral development was influenced by the water temperature: at 20-22 degree C fully formed, infective oncospheres were found after 2 weeks, whereas at 10-12 degree C after 8 weeks. Tubificid oligochaete Tubifex tubifex (Mull.) was proved to serve as an experimental intermediate host of K. baltica. Larvae (procercoids) developed at 20-22 degree C very quickly, becoming infective for the definitive host as early as one month (30-31 days) post infection. On the other hand, the development of tapeworms in experimentally infected definitive hosts, tench, kept at 15-16 degree C was extremely slow and juvenile tapeworms, closely resembling by their size and morphology procercoids from tubificids, were found even 11 weeks p.i.

• 1993. Lang, C. and O. Reymond. Recovery of Lake Neuchatel (Switzerland) from eutrophication indicated by the oligochaete communities. Archiv Fuer Hydrobiologie 128(1): 65-71.

  Abstract: In lake Neuchatel (Switzerland), total phosphorus concentration decreased from 42 mg cntdot m-3 in 1982 to 21 mg cntdot m-3 in 1991. To assess the effects of this recovery at the level of sediment, tubificid and lumbriculid communities were sampled in 1984 and again in 1992. Abundance of some species (mostly Potamothrix hammoniensis and Tubifex tubifex), dominant in eutrophic lakes, decreased in 1992. As predicted from the phosphorus decrease, mean relative abundance of oligotrophic species (mostly Stylodrilus heringianus and Peloscolex velutinus) increased in oligochaete communities from 16% in 1984 to 33% in 1992. According to these values, Lake Neuchatel was deemed mesoeutrophic in 1984, but mesotrophic in 1992. The same pattern of recovery was observed for oligotrophic species in Lake Geneva (Switzerland) between 1982 and 1991.

• 1993. Wiegand, M. and H. Matthess. Oligochaete species of the northern part of the river Rhine. Limnologica 23(2): 145-151.

  Abstract: From the northern part of the river Rhine 49 oligochaete species were recorded. The dominant species was Limnodrilus hoffmeisteri. Tubifex newaensis, Pristina osborni and Aeolosoma leidyi were recorded for the first time from the European Central Low Mountain Range.

• 1993. Bonacina, C., G. Bonomi, S. Gazzera and A. Pasteris. Investigations on the structure, dynamics and distribution of macrobenthos in a pumped storage system. Rivista Di Idrobiologia 30(1): 103-135.

  Abstract: The profundal macrobenthos of Suviana and Brasimone reservoirs (Apennino Tosco-Emiliano, N-Italy) was quantitatively sampled during 1986-87. Tubificid oligochaetes are a major component of the community in both lakes. In Suviana Tubifex tubifex and Limnodrilus hoffmeisteri are dominant; in Brasimone Branchiura sowerbyi is also present. The bivalve mollusk Pisidium is quite abundant whereas chironomids are scarce. While the species composition of the two communities is similar, in Brasimone the population densities are much lower than in Suviana and in other Italian reservoirs investigated; the same holds for the specific fecundity of T. tubifex calculated by means of a simple mathematical model. The reason for that is probably the limiting food availability in Brasimone due to the low productivity and to the hydraulic characteristics (very high flushing rate) of this reservoir. Peculiar of this lake is also the presence, in the profundal zone, of empty shells of Bithynia and Valvata. In Suviana the relative species abundance changes along the main axis of the reservoir. T. tubifex increasing its dominance with the depth.

• 1993. Lang, C. and O. Reymond. Eutrophication of Lake Morat indicated by the oligochaete communities: 1980-1991 trend. Revue Suisse De Zoologie 100(1): 11-18.

  Abstract: In the profundal of Lake Morat (Switzerland), macrozoobenthos was mainly constituted by tubificid worms. Total biomass of worms increased with depth, but species showed two different patterns of distribution. Firstly, abundance of Potamothrix moldaviensis and Limnodrilus profundicola strongly decreased with depth. Secondly, Potamothrix hammoniensis and Tubifex tubifex, species typical of eutrophic lakes, increased with depth, so they were the only species present in the deepest area (45 m deep). The same distribution patterns have been repeatedly observed in 1980, 1984 and 1991. This persistence indicate that the oligochaete communities failed to respond to the decrease of phosphorus concentrations recorded between 1980 and 1988.

• 1993. Young, J.O., A.J. Martin and R.M.H. Seaby Competitive interactions between the lake-dwelling leeches Glossiphonia complanata and Helobdella stagnalis: An experimental investigation of the significance of a food refuge. Oecologia (Heidelberg) 93(2): 156-161.

  Abstract: The glossiphoniid leeches Helobdella stagnalis and Glossiphonia complanata co-exist on the stony shores of British lakes. Because both species have a similar lifestyle and are food limited, the question arises as to how coexistence persists. Laboratory experiments investigated if either leech has a competitive advantage on three foods, viz. oligochaete worms (Tubifex sp.), snails (Lymnaea peregra), and a worm-plus-snail mixture. A variety of densities with a range of ratios of the two leeches, and monospecific controls were used. The level of feeding ensured increasing food shortage with rising leech density. Experiments, conducted at 14 degree C, lasted 3 months. Regression values for growth against density in the controls indicated the occurrence of intraspecific competition in both leech species. Light mortality occurred at the highest densities. G. complanata gained significantly less weight in mixed leech cultures than in monospecific cultures at some of the highest densities when fed worms, but more weight when fed on snails. The opposite was true for H. stagnalis. When both prey types were provided, no differences at any density were observed for either leech. Differences in body-size and feeding strategy between the leeches may be implicated in determining their feeding success on the prey types. Because the anti-predatory responses (e.g. shaking) exhibited by L. peregra are less when encountering an inactive than an active leech, the sit-and-wait strategy of G. complanata may aid snail capture. In contrast, the seek-out strategy of H. stagnalis, coupled with its relatively smaller size, may result in fewer successful captures. The active hunting strategy of H. stagnalis may be advantageous for the capture of oligochaetes which are relatively less mobile than snails. Offering both prey types simultaneously would have had an ameliorating influence on interactions between the two leeches. Findings provide support for the hypothesis that long-term co-existence between the two glossiphoniids in British lakes may depend, in part at least, on the occurrence of a snail food refuge for G. complanata.

• 1993. Diaconu, I., A. Vadineanu and G. Risnoveanu. Changes of the structure and functioning of the benthic oligochaete communities from the Danube Delta aquatic ecosystems (1976-1982): 1. Dynamics of the structure of the communities and their dominant populations. Revue Roumaine de Biologie Serie de Biologie Animale 38(2): 171-179.

  Abstract: The research activities have focused on the structure of benthic communities, especially on the dominant oligochaete populations. The spatial and temporal dynamics of oligochaete populations and their spatial distribution were investigated in some aquatic ecosystems of the Danube Delta, during 1976-1982. The criteria of dominance accepted by us, criteria that are based on the numerical and gravimetrical abundance level, were fulfilled by one (Porcu lake), two (Matita, Merhei lakes) or three (Rosu, Puiu lakes) populations of oligochaete, belonging to five different species (Potamotrix hammoniensis, Branchiura sowerbyi, Limnodrilus hoffmeisteri, Tubifex tubifex and Ilyodrilus templetoni). Most of these populations had a clumped spacing.

• 1993. Hoffmann, K.H. and A. Wulf. Comparative studies of integumentary uptake of short-chain carboxylic acids by freshwater oligochaetes. Comparative Biochemistry And Physiology A Comparative Physiology 104(1): 169-174.

  Abstract: Freshwater oligochaetes can take up considerable amounts of acetate and propionate (short-chain, volatile fatty acids, Vfa) from artificial tap water at concentrations of 50-3000 mu-M. Four species of oligochaetes which are studied in this paper, Tubifex tubifex, Limnodrilus hoffmeisteri, Iliodrilus templetoni (Tubificidae) and Lumbriculus variegatus (Lumbriculidae) differ considerably in their mechanisms of Vfa uptake as well as in the absolute amounts absorbed. In T. tubifex, acetate and propionate uptake results from a combination of saturable (mediated) and nonsaturable (diffusional) transport. Both, L. hoffmeisteri and I. templetoni take up acetate by a mediated transport system, whereas propionate is absorbed passively. In L. variegatus, no evidence for a mediated transport system is found. The relevance of the results to the biochemical ecology of the freshwater oligochaetes is discussed.

• 1992. Alam, N. M.; Shafi, M. Toxicity of metacid to Tubifex. Bangladesh Journal of Zoology. 20(1): 203-205.
• 1992. Erseus, C. Groundwater and marine intertidal Tubificidae (Oligochaeta) from the Canary and Cabo Verde Islands, with descriptions of two new species. Bijdragen Tot De Dierkunde 62(2): 63-70.

  Abstract: Seven species of Tubificidae are recorded from the Canary Islands, viz. Heterodrilus amplus n. sp., Coralliodrilus leviatriatus Erseus, 1979, Limnodriloides agnes Hrabe, 1967, L. janstocki n. sp., Aktedrilus cuneus Erseus, 1984, A. parvithecatus (Erseus, 1978), and Tubifex tubifex (Muller, 1774); the two latter taxa are reported also from the Cabo Verde Islands. All taxa except T. tubifex are marine and there is no evidence of endemism in the freshwater oligochaete fauna of these islands. Heterodrilus amplus has short, spindle-shaped, heavily muscular atria; they are morphologically unique within the genus. Limnodriloides janstocki has modified spermathecal setae; it is distinguished from similar species by its long atrial ducts and deep, elaborate copulatory sacs.

• 1992. Ahamed, M.T. and M.F.A. Mollah. Effects of various levels of wheat bran and mustard oil cake in the culture media on the tubificid production. Aquaculture 107(1): 107-113.

  Abstract: Tubificid worms showed a production of 419.4 mg/cm-2 in 60 days in a culvert system under running water in a medium containing 35% wheat bran, 20% mustard oil cake, 25% cow dung and 20% fine sand. New offspring appeared after 20 days from the start of the experiment, and 2.85 g raw materials produced 1.0 g of worms.

• 1992. Jonasson, P.M. The ecosystem of Thingvallavatn: A synthesis. Oikos 64(1-2): 405-434.

  Abstract: Thingvallavatn (Iceland) lies at 64 degree 10'N and 21 degree 10'W in the subarctic 30 to 40 km from the southwest coast of Iceland at 100.5 m a.s.l. Annual mean air temperature was 2.8 degree C for the period 1974-1988. The annual range at Thingvellir is 12.5 degree C. Mean annual precipitation on the lake itself is 1300-1400 mm. Global radiation is 313 times 10-7 kJ m-2 yr-1. The basin is formed by tectonic subsidence and glacial erosion, but has since the glacial recession been strongly modified by volcanic activity. The catchment area is characterized by lava flows, of which four entered the lake, and one dammed it. One eruption occurred within the lake. Fault movements have resulted in horizontal and vertical displacement. Soils around the lake are of aeolian origin, well drained, with a low content of clay and a mineral fraction consisting mainly of volcanic ash, susceptible to water and wind erosion. Vegetation is characterized by absence of trees. Contemporary woodland around the lake is mostly confined to protected areas. Plant communities of the open rangelands of the area are moss heath, dwarf shrub heath, graminoid heath and wetlands. The lake is 83 km-2, with a mean depth of 34 m, and a maximum depth of 114 m. The catchment area is 1000 km-2, of which 50% is postglacial lava. Interglacial lavas and subglacially formed mountains rising to 800-1100 m, glaciers and glacial deposits account for another 50%. The mean discharge of the last 50 yr is 100 m-3 s-1. The precipitation, estimated at 2000-2500 mm yr-1 in the catchment area, is mostly percolated; hence the lake is 90% spring-fed. The main spring areas in the north show a constant temperature of 2.8-3.5 degree C. Warmer ground water (7.5-10.7 degree C) enters the lake in the southwest owing to the nearby Hengill geothermal area. The water level has been regulated since 1959. The lake is dimictic and the temperature commonly reaches 10-11 degree C in August with a gradient of 2-3 degree C through the thermocline. On an average, the ice-cover lasted 95 d during the period 1974 to 1990. The nutrients N, P and Si enter the lake at fluxes of 1.4, 0.8 and 240 mg m-2 yr-1. Phytoplankton production is N-limited. Two main energy pathways characterize the lake. The pelagic community is simple with few species (48 phytoplankton, three crustacean zooplankton and one fish species), while the benthic community is more complex with ca: 150 phytobenthic algae, ca. 60 zoobenthic and two fish species. The euphotic layer varies between 20 m in spring and 40 m in summer. Phytoplankton production is bimodal with a spring and early autumn peak of diatoms and a summer minimum of mainly Chrysophyceae. Mean annual production is 95 g C m-2 (4000 kJ m-2). Average biomass is 50 kJ m-2 resulting in an annual P/ hivin B ratio of 64. Zooplankton biomass averages 50 kJ m-2 and net production amounts to 210 kJ m-2 yr-1 giving an annual P/ hivin B ratio of 4.2. Net production of planktivorous arctic charr feeding mainly on zooplankton, but also on emerging benthic insects is 28 kJ m-2 yr-1 with an average biomass of 50 kJ m-2 and annual P/ hivin B ratio of 0.54. The phytobenthic communities showed a distinct zonation with more algal zone in the stony littoral to 10 m depth with various fast growing herbivorous zoobenthos assemblages adapted. In the sublittoral from 10-25 m depth a Nitella opaca stand supports a small population of the filtrering Chironomus islandicus. The phytobenthos covers ca. 30% of the total lake area. The profundal zone is dominated by the slow growing detritivorous Tubifex tubifex. Phytobenthos gross production in the littoral and sublittoral zones averages on a lakewide basis 2800 kJ m-1. Average biomass is 500 kJ m-2 with an annual P/ hivin B ratio of 2.6. Zoobenthos (including micro- and meiofauna) production is 100 kJ m-2 yr-1. Annual P/ hivin B ratio decreased from 3.6 in the littoral zone to 1.4 in the profundal zone. Three benthic morphs of arctic charr, and threespine stickleback, feed mainly on zoobenthos. Their annual production averaged 3.4 kJ m-2 yr-1 with an annual P/ hivin B ratio of 0.43. Possible interactions between energy flow in the pelagic and benthic food chains are pointed out.

• 1992. Lindegaard, C. Zoobenthos ecology of Thingvallavatn: Vertical distribution, abundance, population dynamics and production. Oikos 64(1-2): 257-304.

  Abstract: Macrozoobenthos of the medium oligotrophic Thingvallavatn (64 degree N, 21 degree W) is composed of ca. 60 taxa dominated by 24 Chironomidae and 16 Oligochaeta species. Abundance, life cycle, biomass and production were estimated for the 42 dominant taxa. The vertical distribution delimits five communities: (1) the surf zone community from 0 to 2 m, (2) the upper stony littoral community from 2 to 6 m, (3) the lower stony littoral community from 6 to 10 m, (4) the Nitella zone community from 10 to 20 m, and (5) the profundal zone community from 20 to 114 m. Abundance declined from ca. 20000 ind m-2 in the three upper zones to ca. 3500 ind m-2 in the Nitella- and profundal zones, and averaged ca. 5900 ind m-2 on a lakeside basis. By numbers, Tubifex tubifex (37%), Enchytraeidae (14%) and Lymnaea pereger (9%) dominated the average fauna. Life history varied from probably a 7-yr life cycle (Spirosperma ferox) to multivoltinism with a dominance of uni- and bivoltine species. Annual P/B ratio averaged 2.4 with a range from 3.6 in the surf zone to 1.4 in the profundal zone. Annual production varied from 1.2 to 14 g Afdw m-2 in the profundal zone and the surf zone, respectively. L. pereger contributed 26%, T. tubifex 16% and Pseudodiamesa nivosa 12% of the total average production, which, on a lakewide basis, was 3.4 g Afdw or 78 kJ m-2 yr-1. Thingvallavatn thus belongs at the lower end of measured lake zoobenthic productions, which range from 10 kJ m-2 yr-1 in Arctic lakes to ca. 1600 kJ m-2 yr-1 in highly eutrophic shallow lakes.

• 1992. Dratnal, E., P.A. Dratnal and R.W. Davies. The effects of food availability and foraging constraint on the life history of a predatory leech, Nephelopsis obscura. Journal Of Animal Ecology 61(2): 373-379.

  Abstract: Two groups of Nephelopsis obscura, fed ad libitum on Tubifex tubifex, were compared: one was maintained in an environment with a mud substratum (Ms leeches) allowing prey anti-predator responses, the other without a substratum (Ns leeches) providing prey directly available to the leech. Ns leeches showed a 4.7 times higher feeding rate and 3.7 times higher growth rate than Ms leeches resulting in Ns leeches attaining maturity at a mean size of 750 mg after 85 days compared to a mean size at maturity of 270 mg after 109 days for Ms leeches. Direct observation of foraging behaviour of three size-groups of starved N. obscura revealed three foraging modes: immediate prey ingestion; delayed prey ingestion; and no prey ingestion after encounter. The change from the immediate to delayed foraging mode resulted in a threshold above which successful foraging on prey with a mud substratum became impossible. Feeding on directly vulnerable prey without a substratum continued until the gut capacity was reached. The life-history traits exhibited by Ns leeches result from the potential for feeding to gut capacity whie the life-history traits of Ms leeches result from the timetables imposed by the foraging constraint. Based on instantaneous feeding and growth rates of similar sizes of Ns and Ms leeches, coefficient of size-specific feeding ability loss (Fal) and growth ability loss (Gal) were calculated for contrained Ms leeches and shown to be an increasing function of leech size (weight).

• 1991. Yokoyama, H., K. Ogawa and H. Wakabayashi. A new collection method of actinosporeans - a probable infective stage of myxosporeans to fishes - from tubificids and experimental infection of goldfish with the actinosporean, Raabeia sp. Gyobyo Kenkyu. 26: 133-138.
• 1991. Courtney, C.C. and B.M. Christensen The response of Tubifex tubifex (Oligochaeta: Tubificidae) to a second infection with Glaridacris catostomi (Cestoidea: Caryophyllaeidae). Journal Of The Helminthological Society Of Washington 58(1): 118-121.

  Abstract: The response of the aquatic oligochaete, Tubifex tubifex, to primary and secondary infection by the caryophyllaeid cestode, Glaridacris catostomi, was investigated by comparing rates of parasite mortality between the 2 infections. Tubifex tubifex that lost the first infection of G. catostomi became infected after second exposure to the cestode, but rate of parasite mortality did not increase. Over an 8-day period, both cumulative parasite mortality and percentage of hosts that lost their caryophyllaeid infection were greater for the first infection (90% and 59%) than for the second (46% and 2%). A cellular response, involving the encapsulation of metacestodes by host coelomocytes accounted for part of the high caryophyllaeid mortality observed.

• 1991. Reynoldson, T.B., S.P. Thompson and J.L. Bamsey. A sediment bioassay using the tubificid oligochaete worm Tubifex tubifex. Environmental Toxicology And Chemistry 10(8): 1061-1072.

  Abstract: A new technique using the tubificid oligochaete Tubifex tubifex as a standard sediment bioassay is described. The various factors affecting quality assurance and control have been examined, such as the appropriate number of replicates; the sensitivity, discriminatory power, and repeatability of the test; and the effects of temperature, animal size, organic content, density, and duration on the test. The proposed bioassay is simple and straightforward and can be done with readily available and inexpensive equipment. It utilizes reproduction, the most ecologically relevant and sensitive life stage, as an end point and has been shown in the laboratory to be both repeatable and discriminatory. The technique can be recommended for further investigation in field trials and for consideration as part of a suite of assays for use in sediment assessment.

• 1991. D. Steinhagen. Ultrastructural observations on sporozoite stages of piscine coccidia: Goussia carpelli and Goussia subepithelialis from the intestine of tubificid oligochaetes. Diseases Of Aquatic Organisms 10(2): 121-126.

  Abstract: Sporozoites of the piscine coccidians Goussia carpelli and G. subepithelialis excysted from sporocysts when ingested by tubificid oligochaetes Tubifex tubifex and Limnodrilus hoffmeisteri, and invaded cells of the alimentary tract. There the sporozoites were found singly in membrane-bound parasitophorous vacuoles and persisted for 9 wk for G. carpelli and 3 wk for G. subepithelialis. The fine structure of the sporozoites agreed with ultrastructural details known from other eimerian type sporozoites. The cells possessed e.g. refractile bodies, micronemes and dense granules, and were limited by a 3-layered pellicle. G. carpelli sporozoites, which were studied in more detail, showed no alteration in ultrastructure during 9 wk of observation and remained infective for carp.

• 1991. Scholz, T. Early development of Khawia sinensis Hsu, 1935 (Cestoda: Caryophyllidea), a carp parasite. Folia Parasitologica (Prague) 38(2): 133-142.

  Abstract: The development of the tapeworm Khawia sinensis parasitizing carp (Cyprinus carpio L.) has been studied from the release of cestode eggs into water to the formation of infective procercoids in the intermediate host under laboratory conditions. The rate of embryonal development is greatly influenced by the water temperature. While at 5 degree C the development of oncospheres was not recorded, at 10-12 degree C, 15 degree C, 20-22 degree C, and 23-24 degree C oncospheres were fully formed after 57, 42, 21 and 16 days, respectively. Infectivity of oncospheres was confirmed by successful experimental infection of the intermediate hosts: Tubifex tubifex and Limnodrilus udekemiamus (Oligochaeta: Tubificidae). Fully formed procercoids infective for the definitive host were found in the intermediate host from 52 days of development at 20-22 degree C. From the third week of development in the intermediate host, most of the parasite larvae were located in the anterior part of the tubificid body, mainly between 8th and 15th segments.

• 1991. Guerin, C. and L. Labroue. A laboratory study of the effect of Tubifex tubifex Mull. (Tubificidae, Oligochaeta) on the release of phosphorus through the sediment. Annales De Limnologie 27(3): 253-265.

  Abstract: The effect of Tubuficidae of the genus Tubifex on the release of different forms of phosphorus (particulate, dissolved organic and orthophosphates) has been studied in the laboratory under controlled conditions. When the environment is oxygenated, the worms produce an increase in particulate phosphorus in the water column, but at the expense of orthophosphates so that the amount of total phosphorus is scarcely higher than that of a control. When the environment has a low oxygen content, the difference is more marked, chiefly due to the greater abundance of particulate phosphorus. This particulate phosphorus appears to arise from more essential stirring because defacation is reduced by the oxygen deficit. This transfer of orthophosphates to particulate phosphates raises the problem of the biological availability of the latter that condition the positive or negative action of Tubifex on algal nutrition.

• 1991. Guerin, C.; Labroue, L. A laboratory study of the effect of Tubifex tubifex Mull. (Tubificidae, Oligochaeta) on the release of phosphorus through the sediment. Annales de Limnologie 27(3):253-265. (In French with English summary.).
• 1991. Khangarot, B. S. Toxicity of metals to a freshwater tubificid worm Tubifex tubifex Muller. Bulletin of Environmental Contamination and Toxicology 46(6): 906-912.
• 1991. Courtney, C. C.; Christensen, B. M. The response of Tubifex tubifex (Oligochaeta, Tubificidae) to a second infection with Glaridacris catostomi (Cestoidea,Caryophyllaeidae). Journal of the Helminthological Society of Washington 58(1): 118-121.
• 1991. Bonacina, C.; Bonomi, G.; Di Cola, G.;Monti, C. An improved model for the study of population dynamics in Tubifex tubifex (Oligochaeta, Tubificidae). Verhand-lungen. Internationale Vereinigung fur Theoretische und Angewandte Limnologie 24(5):2764-2767.
• 1991. Reynoldson, T. B.; Thompson, S. P.; Bamsey, J. L. A sediment bioassay using the tubificid oligochaete worm Tubifex tubifex. Environmental Toxicology and Chemistry 10(8): 1061-1072.
• 1990. Gluzman, C. Freshwater oligochaeta in stagnant water bodies in Buenos Aires Province, Argentina. Physis Seccion B las Aguas Continentales y sus Organismos 48(114-115): 47-50.
• 1990. Anlauf, A. Cyst formation of Tubifex tubifex (Muller) - an adaption to survive food deficiency and drought. Hydrobiologia 190(1): 79-82.
• 1990. Anlauf, A.; Neumann, D. Genetic differentiation of populations of the oligochaete Tubifex tubifex (Muller). Verh. Dtsch. Zool. Ges. 83: 608. (in German).
• 1989. Marian, M. P.; Chandran, S.; Pandian, T. J. A rack culture system for Tubifex tubifex. Aquacultural Engineering. 8(5):329-337.
• 1989. Paoletti, A. Cohort cultures of Tubifex tubifex. Hydrobiologia. 180: 143-150.
• 1989. Wiederholm, T.; Dave, G. Toxicity of metal polluted sediments to Daphnia magna and Tubifex tubifex. Hydrobiologia 176/177: 411-417.
• 1989. Bonacina, C.; Bonomi, G.; Monti, C. Density-dependent processes in cohorts of Tubifex tubifex, with special emphasis on the control of fecundity. Hydrobiologia 180: 135-141.
• 1989. Bonacina, C.; Bonomi, G.; Monti, C. Population analysis in mass cultures of Tubifex tubifex. Hydrobiologia 180: 127-134.
• 1988? Di Giovanni, M.V. and E. Goretti. Notes to the knowledge of Lake Piediluco, Italy: The benthos. Rivista Di Idrobiologia 27(2-3): 697-714.

  Abstract: In 1979-80 lake bottom samples were taken at 15 stations in Lake Piediluco at monthly intervals using a compressed air sampler in order to analyze the macrobenthos. The animals found were of the followign classes: Gastropoda, Lamellibranchiata, Oligochaeta, Hirudinea, Crustacea, Arachnida and Insecta. The percentage density ratio between the different groups showed: the greatest presence of Annelida-Oligochaeta (52%) mostly Tubifex but also Pristina and Stylaria; a consistent Mollusca popualtion (Bivalvia 21.4%, Sphaerium and Pisidium and Gastropda 7.1%, Planorbis, ancylus, Valvata and Bithynia); a notable Crustacea population (10.1% mostly Asellus aquaticus and Echinogammarus tibaldii) and Insecta (8.8% mostly Diptera Chironomus gr. plumosus, Endochirononomus albipennis, Procladius sp., Tanypus kraatzi, with infrequent findings of Chaoborus sp., Sialis and Sisyra). The annual macrobenthic distribution, at Stations 1, 2, 3 and 5, where the most groups were found, shows the influence of the current created by the convergence of the waters from the Nera River to Lake Piediluco and River Velino. The currents carry a greater oxygen supply to the bottom and re-circulate the nutrients. The appearance of Tubifex, Asellus, Sphaerim and Chironomus gr. plumosus indicates that Lake Piediluco has a mesotrophic status which is confirmed by the fact that the oxygen level never goes below 50%.

• 1987. Bonacina, C.; Bonomi, G.; Monti, C. Population dynamics of Tubifex tubifex, first settler in the profundal of a copper and ammonia polluted, recovering lake (L. Orta, North Italy). [abstract]. Hydrobiologia 155: 305.
• 1987. Finogenova, N. P.; Lobasheva, T. M. Growth of Tubifex tubifex Muller (Oligochaeta, Tubificidae) under various trophic conditions. Internationale Revue der Gesampten Hydrobiologie 72(6): 709-726.
• 1987. Hoffmann, K. H.; Hipp, E.; Sedlmeir, U. A. Aerobic and anaerobic metabolism of the freshwater oligochaete Tubifex sp. [abstract]. Hydrobiologia 155: 157-158.
• 1987. Morev, Yu. b.; Smailova, T. S. Food assimilability by Tubifex tubifex (Oligochaeta). Gidrobiol Zh. 23(2): 67-70.
• 1986. Hoffmann, K. H.; Seuss, J.; Hipp, E.; Sedlmeier, U. A. Aerobic and anaerobic metabolism inTubifex, a freshwater oligochaete. Zool. Beitr. 30(1-3): 153-170.
• 1986. Yoshioka, Y.; Ose, Y.; Sato, T. Testing and evaluation of chemical toxicity on Tubifex. [in Japanese with English summary] Eisei Kagaku [Journal of Hygienic Chemistry] 32(4): 308-311.
• 1986. Lazim, M. N.; Learner, M. A. The life-cycle and productivity of Tubifex tubifex (Oligochaeta; Tubificidae) in the Moat-Feeder Stream, Cardiff, South Wales. Holarctic Ecology 9: 185-192.
• 1985. Putzer, V.; Gnaiger, E.; Lackner, R. Flexibility of anaerobic metabolism in aquatic oligochaetes ( Tubifex sp.). Biochemical and calorimetric changes induced by a deproteinized hydrolysate of bovine blood. Comp. Biochem. Physiol. (Comp. Physiol.) 82A(4): 965-970.
• 1985. Famme, P.; Knudsen, J. Anoxic survival, growth and reproduction by the freshwater annelid, Tubifex sp., demonstrated by using a new simple anoxic chemostat. Comp. Biochem. Physiol. (Comp. Physiol.) 81A(2): 251-253.
• 1982. Chapman, P. M.; Farrell, M. A.; Brinkhurst, R. O. Effects of species interactions on the survival and respiration of Limnodrilus hoffmeisteri and Tubifex tubifex (Oligochaeta, Tubificidae) exposed to various pollutants and environmentalfactors. Water Res. (G. B.) 16: 1405-1408.
• 1982. Dad, N. K.; Qureshi, S. A.; Pandya, V. K. Acute toxicity of two insecticides to tubificid worms, Tubifex tubifex and Limnodrilus hoffmeisteri. Environment International. 7: 361-363.
• 1971. R.O. Brinkhurst and D.G. Cook. Chapter 5 Aquatic earthworms (Annelida: Oligochaeta). in Pollution ecology of freshwater invertebrates, C.W. Hart, Jr. and S.L.H. Fuller eds. Academic Press.
  1. This is a very useful summary of Brinkhurst's and Cook's work up to 1971.
  2. Tubificids are frequently highly clumped in nature in part because of some preference for feces feeding by the various species.
  3. Lumbriculids and naidids often replace tubificids in clean stony streams.
  4. Organic matter loading and the bateria responce are probably more important to tubificids than are the normally measured physical and chemical factors.
  5. Oligochaetes and other non-arthropods can be tollerant to pesticides, but can be more sensitive to metals and acids than are the arthropods.
  6. Tubifex tubifex and Limnodrilus hoffmeisteri are very resistant spcies that may be abundnant in highly disturbed sites, but they are also present in some pristine areas.