Aquatic Oligochaetes Research Articles

Potential for Resource Competition between Eurasian Ruffe and Yellow Perch: Growth and RNA Responses in Laboratory Experiments

Abstract The ruffe Gymnocephalus cernuus, an exotic percid from Eurasia that is now established in limited areas of the Great Lakes, is invading areas currently occupied by native yellow perch Perca flavescens. We conducted two laboratory experiments to determine whether competition for benthic macroinvertebrate food (live aquatic oligochaetes) may occur, thereby resulting in reduced growth for one or both fish species. In the first experiment, we compared the short-term (7-d) growth of ruffe and yellow perch among four treatments: one individual (ruffe or yellow perch), two conspecifics (two ruffe or two yellow perch), one fish of each species together, and two fish of each species together (N = 9 per treatment). Growth was measured both as change in mass and as RNA levels in the white muscle tissue of fish, which is an index of short-term growth. In the second experiment, we looked at longer-term (58-d) growth using three treatments: two conspecifics alone, one fish of each species together, and two fis...

Small Subunit Ribosomal RNA Sequences Link the Cause of Proliferative Gill Disease in Channel Catfish toHenneguyan. sp. (Myxozoa: Myxosporea)

Abstract In a previous study the small subunit ribosomal RNA (SSU rRNA) gene of Aurantiactinomyxon ictaluri, the actinosporean stage (actinospore) of the myxozoan associated with proliferative gill disease (PGD), was sequenced. In this study bath exposures of channel catfish Ictalurus punctatus to A. ictaluri isolated from the aquatic oligochaete Dero digitata were used to study the subsequent development of this parasite and to confirm the SSU rRNA gene sequences of each life stage. On day 7 postexposure, typical PGD organisms were observed in the gills, and at 3 months postinfection, cysts containing the newly identified myxozoan Henneguya sp. spores were observed in the gills. The sequence of the SSU rRNA genes of the actinospore and myxospore life stages demonstrated their identity. This is the first molecular evidence that A. ictaluri, isolated from D. digitata, can infect catfish and produce the typical PGD organisms in the gills. These data provide further proof that the actinospore A. ictaluri is ...

Metabolic response ofLumbriculus variegatusto respiratory uncoupler in cold and anoxic water

AbstractA direct calorimetry approach was applied to compare physiological interaction of pentachlorophenol (PCP) with the energy metabolism under anoxia and normoxia in the aquatic oligochaete wormLumbriculus variegatus.In normoxia, heat dissipation begins to accelerate 10 h after the onset of PCP exposure until it settles at a new plateau level, and shows a twofold increase from the nonimpact rate. In anoxia, heat output was suppressed down to a level of ∼18% (7°C) of normoxia. An anoxic PCP exposure did not produce any notable changes in the heat output, and the amount of chemical accumulated in tissues was only a fraction (18%) of that accumulated in normoxia. Whether the inhibition of the physiological response during anoxia was due to a shift to anaerobic metabolism or to reduced accumulation in tissues, or combination of both factors, was unclear.

Distribution and Abundance of the Aquatic Oligochaete HostTubifex tubifexfor the Salmonid Whirling Disease ParasiteMyxobolus cerebralisin the Upper Colorado River Basin

Abstract Benthic invertebrate samples were collected from six sites in the upper Colorado River basin in north-central Colorado to determine the distribution, abundance, and infection rates of Tubifex tubifex, the aquatic oligochaete host for the salmonid whirling disease parasite Myxobolus cerebralis. The disease has been implicated as a factor in severe recruitment declines in wild rainbow trout Oncorhynchus mykiss in this drainage. In Windy Gap Reservoir, T. tubifex constituted 73% of the oligochaete community, compared with 53% in the Colorado River upstream from the reservoir and 33% in the river downstream. Total oligochaete densities were slightly higher in the reservoir than above or below the reservoir. About 1.2% of the worm population was infected with M. cerebralis in the reservoir; infection rates were similar in the river. In Willow Creek, a tributary to the upper Colorado River, 73% of the oligochaetes at two sites downstream of cattle grazing and riparian-area gravel mining were T. tubifex...

Species Composition and Abundance of Littoral Oligochaete Fauna in Lunuwila Reservoir, Sri Lanka

Species composition and abundance of aquatic oligochaetes in Lunuwila reservoir, a shallow perennial reservoir in Sri Lanka were investigated. Oligochaete fauna in the reservoir was represented by two species of aeolosomatids and nine species of naidids. The naidid Pristina longiseta was the dominant oligochaete species and represented up to 33% of the total oligochaete community in the reservoir. Abundance of total naidids was positively correlated with conductivity, pH, dissolved oxygen, biochemical oxygen demand, nitrate and phosphate levels of the bottom water (p < 0.05). Of the total of nine species of naidids examined, abundance of five species including the dominant species, P. longiseta was positively correlated with dissolved oxygen levels of the bottom water. Dissolved oxygen level of the bottom water seems to be a more significant determining factor in the abundance of naidid community in the reservoir than the other environmental factors. Species composition and low population densities of aquatic oligochaetes along with organic pollution indicative water quality parameters in Lunuwila reservoir indicate that the reservoir has not yet been subjected to severe organic pollution.

Species Composition and Abundance of Littoral Oligochaete Fauna in Lunuwila Reservoir, Sri Lanka

Species composition and abundance of aquatic oligochaetes in Lunuwila reservoir, a shallow perennial reservoir in Sri Lanka were investigated. Oligochaete fauna in the reservoir was represented by two species of aeolosomatids and nine species of naidids. The naidid Pristina longiseta was the dominant oligochaete species and represented up to 33% of the total oligochaete community in the reservoir. Abundance of total naidids was positively correlated with conductivity, pH, dissolved oxygen, biochemical oxygen demand, nitrate and phosphate levels of the bottom water (p < 0.05). Of the total of nine species of naidids examined, abundance of five species including the dominant species, P. longiseta was positively correlated with dissolved oxygen levels of the bottom water. Dissolved oxygen level of the bottom water seems to be a more significant determining factor in the abundance of naidid community in the reservoir than the other environmental factors. Species composition and low population densities of aquatic oligochaetes along with organic pollution indicative water quality parameters in Lunuwila reservoir indicate that the reservoir has not yet been subjected to severe organic pollution.

Alterations in prey capture and induction of metallothioneins in grass shrimp fed cadmium‐contaminated prey

AbstractThe aquatic oligochaete Limnodrilus hoffmeisteri from a Cd‐contaminated cove on the Hudson River, Foundry Cove, New York, USA, has evolved Cd resistance. Past studies have focused on how the mode of detoxification of Cd by these Cd‐resistant worms influences Cd trophic transfer to the grass shrimp Palaemonetes pugio. In the present study, we investigate reductions in prey capture in grass shrimp fed Cd‐contaminated prey. We also investigate the induction of metal‐binding proteins, metallo‐thioneins, in these Cd‐exposed shrimp. Grass shrimp were fed field‐exposed Cd‐contaminated Foundry Cove oligochaetes (for 1 week) or laboratory‐exposed Cd‐contaminated Artemia salina (for 1 or 2 weeks). Following these exposures, the ability of Cd‐dosed and control shrimp to capture live A. salina was compared. Results show that shrimp fed laboratory‐exposed Cd‐contaminated A. salina for 2 weeks exhibit significant reductions in their ability to successfully capture prey (live A. salina). Reductions in prey capture were also apparent, though not as dramatic in shrimp fed for 1 week on field‐exposed Cd‐contaminated Foundry Cove oligochaetes. Shrimp were further investigated for their subcellular distribution of Cd to examine if alterations in prey capture could be linked to saturation of Cd‐metallothionein. Cd‐dosed shrimp produced a low molecular weight (∼10,000 daltons) Cd‐binding metallothionein protein in a dose‐ and time‐dependent manner. Most importantly, successful prey capture decreased with increased Cd body burdens and increased Cd concentration bound to high molecular weight proteins (i.e., enzymes).

Influences of riparian logging on plants and invertebrates in small, depressional wetlands of Georgia, U.S.A.

We studied 12 small, seasonally flooded, depressional wetlands on the Atlantic Coastal Plain of Georgia, U.S.A. Each wetland was embedded in stands of managed plantation pine. The pine trees surrounding each wetland had been harvested and replanted beginning in 1997 (2 sites), 1995 (2 sites), 1993 (1 site), 1988 (2 sites), 1984 (2 sites) or 1975 (3 sites). Regressions of various environmental variables with harvest histories indicated that those wetlands surrounded by smaller trees had greater light levels, water temperatures, pH, herbaceous plant cover and biomass, terrestrial invertebrate diversities and numbers, and water flea numbers, and lower water electrical conductivities and aquatic oligochaete numbers than those wetlands surrounded by more mature trees. Detected variations in hydroperiod, water depth, dissolved oxygen levels, sediment inputs, macrophyte diversity, periphyton biomass and densities of most aquatic invertebrates were not clearly correlated with past histories of peripheral tree harvest. This study suggests that harvesting trees around small wetlands initiates physical and ecological changes within the embedded habitats and that changes can persist for up to 15 years.

Metallothionein-like proteins in the freshwater oligochaete Limnodrilus udekemianus and their role as a homeostatic mechanism against cadmium toxicity

The purpose of this study was to determine if metallothioneins are present in the aquatic oligochaete Limnodrilus udekemianus and to determine the interplay between the presence of these proteins, cadmium (Cd) exposure, and Cd toxicity. The latter was geared specifically towards evaluating the role of metallothionein as a homeostatic mechanism against Cd toxicity. These issues are important for evaluating the usefulness of the quantification of metallothioneins as a biomonitoring tool. Worms in sediment were exposed to Cd under static conditions, with Cd initially added to the aqueous phase. Survival was monitored while respiration (as a measure of sublethal Cd effects) was determined immediately following exposure. Metallothioneins were separated from the cytosol by gel permeation high performance liquid chromatography (HPLC) while Cd levels were quantified in whole worms, cytosol and cytosolic fractions. Also, a Cd-saturation assay was used to determine the amounts of Cd bound to metallothionein and the total Cd-binding capacity of the metallothionein. Limnodrilus udekemianus has a metallothionein-like protein (an inducible cytosolic protein with an apparent molecular weight of approximately 15 kD that binds high levels of Cd and shows a red shift upon Cd binding). Sediment Cd levels above 60 μg/g were lethal to the worms (in 8-day exposures). Respiration rates at 13 and 41 μg/g Cd were not significantly different from controls, though cytosolic Cd levels were substantially increased in the 41 μg/g exposure. In this latter cytosol, Cd levels were significantly elevated in the low molecular weight pool (which includes metallothioneins) but not in the other pools, while the Cd-saturation assay also showed that worms in this group had significantly elevated levels of metallothionein-bound Cd. However, in all treatments the metallothionein was far from saturated by Cd. These observations indicate that no ‘spill-over’ of Cd was evident as lethal levels of Cd were approached. The overall cytosolic Cd distribution, and the degree of metallothionein saturation in Limnodrilus udekemianus thus do not appear to be good predictors of Cd toxicity in this species.

An original decontamination process developed by the aquatic oligochaete Tubifex tubifex exposed to copper and lead

The aquatic oligochaete Tubifex tubifex is known to be very resistant to pollution, however, the way this organism has adapted is poorly understood. T. tubifex was present in our study-site (Reuil sur Marne, Marne, France), a retention basin that receives contaminated runoff water from a vineyard. Field observations showed that a large proportion of the worms had abnormal caudal regions (completely missing or regenerating). After experimental contamination with subacute concentrations of copper and lead, two metals that cause problems in the vineyards, the animals lost their tails. Metal determinations in the anterior and posterior parts of whole T. tubifex from the polluted site and experimentally contaminated worms revealed a higher concentration of metals in the posterior part. These results indicated that T. tubifex may protect itself against the increase of internal concentrations of toxic metals (Cu and Pb) by the autotomy of the caudal region in which the metals had accumulated. The capacity of the worms to regenerate was not impaired, even in contaminated medium. The possibility to use the loss of tail as a biomarker of contamination is discussed.

Studies on the Aquatic Oligochaete Fauna in Lake Biwa, Central Japan. III. Distribution of Respective Taxa within the Lake.

Forty oligocheate taxa were recorded from 133 sites of various depths and habitats of Lake Biwa from 1984 to 1998. They belong to 23 taxa of Naididae, 15 of Tubificidae, 1 each of Biwadrilidae and Lumbriculidae, which cover 75% of the known aquatic oligochaete fauna in Japan. Among 40 taxa, 37 were from the littoral, 17 from the sublittoral, and 15 species from the profundal habitat. In the mesotrophic northern basin 36 taxa were collected, 5 species of which were exclusive. In the eutrophic southern basin, 35 taxa were collected, 3 species being solely reported. The taxa were categorized into 4 groups of distributional patterns in the lake : (1) 23 taxa, including a lumbriculid, a biwadrilid, 17 naidids and 4 tubificids, distributed in the littoral habitat of both basins and in small inlets, (2) 2 naidids distributed in the littoral and sublittoral habitat of the northern basin, (3) 2 tubificids distributed in the sublittoral and profundal habitat of the northern basin, and (4) 4 naidids and 9 tubificids distributed widely over whole range of the lake. On the whole, tubificids are widely distributed in the lake, whereas a lumbriculid, a biwadrilid and two-thirds of the naidids were distributed exclusively in the littoral habitat of both basins.

Small subunit ribosomal RNA sequence of Henneguya exilis (class Myxosporea) identifies the actinosporean stage from an oligochaete host.

Several transmission studies, as well as recent molecular data, have indicated that the two classes Myxosporea and Actinosporea represent different life cycle stages of Myxozoa. To evaluate the life cycles of myxozoa in catfish aquaculture systems, the small subunit (18S) ribosomal RNA gene sequences of Henneguya exilis, a myxosporean from channel catfish Ictalurus punctatus, and an actinosporean (previously designated as Aurantiactinomyxon janiszewskai) from the aquatic oligochaete Dero digitata were determined. The sequences were identical, indicating that H. exilis and the actinosporean are alternate life stages of a single species. This is the first report identifying the actinosporean stage of the genus Henneguya.

Whirling disease: re-emergence among wild trout.

Whirling disease of rainbow trout is caused by Myxobolus cerebralis, a myxozoan parasite possessing a life cycle well adapted to the natural environments where salmonid fish are found. Whirling disease was first described in Europe in 1898 among farmed rainbow trout but recent occurrences have been devastating to wild trout in North America. The disease is considered a major threat to survival of wild rainbow trout in the intermountain west of the United States. Difficulties in containing the spread and potentially eliminating the pathogen are tied to features of a complex life cycle involving two hosts, the salmonid fish and an aquatic oligochaete. Details of the morphologic development of the parasite have been described in each host but only now are we beginning to appreciate the breadth of interactions between these developmental forms and the sequential responses of the host. Fundamental mechanisms of the recognition and attachment of the parasite to the hosts, how host immunity is evaded and the unknown influences of environmental factors all contribute to a rather poor understanding of the biology of the parasite. Although the biology and ecology of the salmonid host are better known than for the oligochaete host, our knowledge is inadequate to interpret their complex interactions with the parasite. This uncertainty precludes the development of effective management activities designed to enhance the viability and productivity of wild trout populations in M. cerebralis-positive river systems. Improving our understanding of the hosts, the parasite and the environmental factors determining their interaction should provide for more focused and effective control methods for containing the spread and devastating effects whirling disease is causing to our wild trout populations.

Myxobolus cerebralis in Tubifex tubifex from a Whirling Disease Epizootic in Montana

Aquatic oligochaetes from a whirling disease enzootic area in southwest Montana were examined for infection with Myxobolus cerebralis. Anterior portions of oligochaetes were preserved for specific identification, whereas DNA was purified from posterior portions. The purified DNA was used in a nested polymerase chain reaction (PCR) assay specific for M. cerebralis small-subunit ribosomal DNA. Naturally infected oligochaetes were identified by a resulting 415-bp fragment of amplified parasite DNA. A total of 704 oligochaetes was tested from April through September 1997. Eighteen (2.6%) oligochaetes were infected with M. cerebralis as defined by the nested PCR assay. Two of these were identified as mature Tubifex tubifex, and the others were likely T. tubifex but were immature and lacking the diagnostic reproductive structures. This is the first report of T. tubifex naturally infected with M. cerebralis.

A new species ofFridericia(Oligochaeta : Enchytraeidae) found in a spring in the Sudety mountains (Poland)

A new species, Fridericia dissimilis n. sp., found during a study of the aquatic oligochaete fauna in the region of [math]nie[math]nik Massive (Sudety Mts, south-western Poland) is described. The species belongs to the Fridericia group of species characterised by asymmetrical spermathecae with a single diverticulum, but it is easily distinguished from other species by, the enormous size of the gland at the ectal orifice of the spermatheca and the shape of ampulla, andby the shape of the brain and seminal vesicles.

Small subunit ribosomal RNA sequences unite alternate actinosporean and myxosporean stages of Myxobolus cerebralis the causative agent of whirling disease in salmonid fish.

The alternating myxosporean and actinosporean stages of the myxozoan parasite Myxobolus cerebralis (Hofer 1903) from its salmonid fish and aquatic oligochaete hosts, respectively, were compared for sequence homology of the small subunit (18S) ribosomal RNA genes. A 99.8% similarity between the sequences of these two stages was substantially greater than that of M. cerebralis compared to two other Myxobolus sp. from salmonid fish. Our results are the first molecular evidence confirming the alternating stages, initially described by Wolf and Markiw [25] for the life cycle of M. cerebralis but found in two different taxonomic classes (Myxosporea and Actinosporea) are indeed forms of the same organism. Sequencing of rRNA genes of the actinosporean stage followed by development of specific primers for DNA amplification of the myxosporean stage, as in our study, should be applied to solve other myxozoan life cycles. Additionally, these approaches will in the future provide useful diagnostic reagents for the detection and study of this important group of fish pathogens.

The use of a simultaneous multiple species acute toxicity test to compare the relative sensitivities of aquatic organisms to mercury

Recently there has been concern in the scientific community about observed declines in some amphibian populations. These population declines may be reflecting a global phenomenon or may be part of a natural cycle. Both viewpoints suggest that the observed declines are due to the general sensitivity of amphibians to their environment and to contaminants in their environment. To begin to determine if amphibians are more sensitive to environmental contaminants than other aquatic organisms, a simultaneous, multi‐species toxicity test was conducted. By simultaneously exposing several species of aquatic organisms to a series of mercury concentrations, the relative sensitivities of the organisms could be determined. Six aquatic species were used in the toxicity test: three amphibians, Rana catesbeiana (bullfrog), R. clamitans (green frog), and R. sphenocephala (southern leopard frog); two fish, Gambusia qffinis (mosquitofish) and Notemigonus crysoleucas (golden shiner); one aquatic oligochaete, Lumbriculus variegatus (aquatic earthworm). The organisms were exposed to a series of five test concentrations (1.4, 3.9, 12.0, 110.0, and 487.0 μg Hg/L). The resultant 96hr‐ LC50 values produced the following rank order: R. sphenocephala, 6.59 μg Hg/L; R. clamitans, 14.7 μg Hg/L; N. crysoleucus, 16.75 μg Hg/L; L. variegatus, 43.72 μg Hg/L; G. affinis, 52.62 μg Hg/L; R. catesbieana, 63.36 μg Hg/L. No general organism class sensitivity trend was developed from the data, contrary to the implicit suggestions of some researchers.

環形動物貧毛類の増殖に及ぼす環境因子の影響

Small aquatic Oligochaetes are the typical metazoa found frequently in the activated sludge and bio-film from wastewater treatment system. Effect of environmental factors on growth characteristics of aquatic Oligochaetes, Aeolosoma hemprichi, Pristina longiseta, Nais variabilis were investigated. Using a sterilized activated sludge as the metazoan food, the monoxenic growth rate of small aquatic Oligochaetes, the effects of temperature, pH, phosphate buffer solution concentration, shake stress, food concentration were measured. Optimum temperature of A.heyprichi, P.longiseta, N.variabilis were 30, 35, 35°C, respectively. Phosphate buffer concentration which could grow normally were 1/375M for A. hemprichi, 1/150M for P. longiseta and N.variabilis. The optimum pH values in cultivating the Oligochaetes ranged from 5 to 9. The endurance of A. hemprichi against shake stress was higher than that of P. longiseta and N.variabilis.

マイクロコズムを用いた陰イオン界面活性剤の水圏生態系に及ぼす影響評価

Microcosm system was applied to assess effect of anionic surfactant (LAS) on aquatic ecosystem. Anionic surfactant such as LAS was added to an flask microcosm consisting of four species of bacteria as decomposer, one species of ciliate protozoa (Cyclidium glaucoma), two rotifers (Philodina sp. and Lepadella sp.) and one aquatic oligochaete (Aeolosoma hemprichi) as predator, and a green alga (Chlorella sp.) and a filamentous blue-green alga (Tolypothrix sp.) as producer, comparing with that of an natural lake model ecosystem derived from natural lake water. In the flask microcosm system and the natural lake model ecosystem, biodegradation rates of LAS were almost same and NOECs (no observed effect concentration) of LAS were also below 1.5 mg·l-1. It was found that flask microcosm test could provide precise ecological effect assessment of LAS on number of microorganisms because the system showed higher reproducibility and stability than natural lake model ecosystem. It was suggested that flask microcosm test was useful ecological effect assessment method which can reflect natural aquatic ecosystem.

Osmoregulation in two aquatic oligochaetes from habitats with different salinity and comparison to other annelids

Osmoregulation in two aquatic oligochaetes from habitats with different salinity and comparison to other annelids