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Article Reference Dispersal mechanisms in amphipods: A case study of Jassa herdmani (Crustacea, Amphipoda) in the North Sea
Jassa herdmani (Walker 1893), a tube-building amphipod typical of hard substrates, was found in large densities on shipwrecks from the Belgian part of the North Sea, in association with the hydrozoan Tubularia indivisa. In this area, shipwrecks only represent the source of hard substrates in an environment dominated by soft sediments. Nevertheless, the long-distance dispersal of Jassa species has never been investigated. Therefore, we tested the hypothesis of dispersal with currents, by investigating the behaviour of J. herdmani in the laboratory. Size distribution revealed that newly released juveniles (1 mm) predominated throughout the year and the lower frequency of the size class 1-3 mm indicates a high mortality or a dispersal at this life stage. Individuals of J. herdmani may initiate actively the transport by tidal or surface currents by swimming to the surface of the water or by floating at the surface, as suggested by behaviours noted in the laboratory. The reaction of the amphipods to a current was investigated in the laboratory. We could not detect any sexual function associated with drifting and there was also no preponderance of a size class in the drifting individuals. When testing different substrates, we observed a significant influence of the substrate type on the frequency at which drifting occurred: J. herdmani showed a better adherence on T. indivisa compared to other substrates. Finally, the amphipod showed also a preference for its host compared to other substrates, which suggests a possible detection mechanism. © 2007 Springer-Verlag.
Located in Library / RBINS Staff Publications
Article Reference Octet Stream Metallothionein gene and protein expression as a biomarker for metal pollution in natural gudgeon populations
Gudgeons (Gobio gobio) from historically Cd and Zn contaminated sites in Flanders (Belgium) were found to be resistant to elevated Cd levels. In previous work, this increased resistance was largely explained by increased metallothionein (MT) expression. Recently, environmental cleanup efforts resulted in a significant decrease in Cd concentrations in the surface water. In this study, we evaluated the use of hepatic metal and metallothionein (MT) concentrations as biomarkers of metal exposure before and after the cleanup. Hepatic MT mRNA levels were determined after the environmental metal levels decreased in order to assess the applicability of MT gene expression as an environmental biomarker in natural fish populations. Our data show that both metallothionein protein and gene expression have the potential to be sensitive biomarkers for metal exposure. Significant correlations were found (a) among accumulated metal concentrations and both MT protein and mRNA levels, and (b) between MT protein and mRNA levels. However, our data illustrated that while MT protein and gene expression give a quantitative picture of metal load at a single time point, quantitative information in natural populations cannot always be obtained when different time points (including different years) are compared, since MT gene and protein expression are affected by many other factors in addition to the metal load. Furthermore, the result of the environmental cleanup was reflected in a decrease of hepatic Cd concentrations. Zn remained the most important factor determining MT concentrations. Finally, two differently sized MT mRNAs were amplified to test the hypothesis that 3′-UTR length can offer a protective advantage in conditions of environmental stress. Our data provided no evidence to support this hypothesis. In contrast, the ratio of the long mRNA variant relative to total MT mRNA was surprisingly constant, and independent of exposure history. © 2007 Elsevier B.V. All rights reserved.
Located in Library / RBINS Staff Publications
Article Reference First record of the rotifer Lecane shieli Segers and Sanoamuang, 1994 from Australia
The monogonont rotifer Lecane shieli is recorded for the first time from Australia (Bora Channel in the Macquarie Marshes, New South Wales: 30.65872° S/147.53 144° E). Until recently, L. shieli was known only from Thailand, where the species was first described. This Australian record of a Thai 'endemic' is interesting in considering possible dispersal and biogeographical distribution.
Located in Library / RBINS Staff Publications
Article Reference Restoration of tropical peat swamp rotifer communities after perturbation: An experimental study of recovery of rotifers from the resting egg bank
In order to assess the recovery potential of tropical freshwater communities after disturbance, we performed an experimental study on the effects of exposure conditions and durations of storage on hatching of rotifer resting eggs in sediment. Well-mixed surface sediment samples from Mai Khao peat swamp on Phuket Island, Thailand, were stored under three conditions (cold -4°C & dark: CD; ambient -32-42°C & dark: AD; and ambient & daylight conditions: AL), for different periods of time (1, 2, 4, 6, 12, 18 and 24 months). The number of species hatching from the sediment was significantly affected by treatment for both short- (1-6 months) and long-term (6-20 months) exposure. Significant effects of short- and long-term exposure within treatments were also present. Both factors interacted significantly. Regarding numbers of specimens hatching, no short-term effects of differences in treatment condition were found, but increasing the duration did have an effect. Significant effects of treatment occurred after 6 months, in addition to prolonged effects of duration. Again, both factors interacted significantly. These experiments indicate that exposure time has a strong impact on the viability of resting eggs, whereas, an effect of exposure condition appears only after 6 months. So, recovery of rotifer communities from resident sediment egg banks in disturbed peat swamps can only be effectively attained when restoration occurs within a relatively short period after perturbation. © Springer 2005.
Located in Library / RBINS Staff Publications / Pending Duplicate Bibliography Entries
Article Reference New metallothionein mRNAs in Gobio gobio reveal at least three gene duplication events in cyprinid metallothionein evolution
This paper reports the identification and analysis of the primary structure of three novel metallothionein cDNA sequences in the gudgeon, Gobio gobio (Cyprinidae). Two different 180 bp coding regions were identified, resulting in two MT isoforms differing in one amino acid. The primary structure of the amino acid sequence was compared to other cyprinid MT sequences. Furthermore, two differently sized cDNAs were discovered in one of the two transcripts. We present a phylogenetic comparison of our sequences to other, previously published cyprinid MT gene sequences. Our analysis reveals an unexpected complexity in cyprinid MT evolution, with at least three gene duplication events. Differences and homologies between the evolution of cyprinid MT genes are compared to other teleost families. Finally, possible implications for metallothionein classification are discussed. © 2005 Elsevier Inc. All rights reserved.
Located in Library / RBINS Staff Publications / Pending Duplicate Bibliography Entries
Article Reference Paracrenhydrosoma oceaniae sp. nov. (Copepoda: Harpacticoida), from Kongsfjorden, Northwest Svalbard (Arctic)
Both sexes of a new species of Cletodidae belonging to the Acrenhydrosoma-lineage are described from material collected at Kongsfjorden (Svalbard) and attributed to the genus Paracrenhydrosoma Gee, 1999. Paracrenhydrosoma oceaniae sp. nov. is easily distinguished from its congeners by the reduced setal formula of the natatorial legs, lacking the inner subdistal seta on segment 3 of legs 3 and 4. Several other characteristics viz. antennular and antennal armature, and the free leg 5 exopodite in both sexes, are indications of its basal position in the genus.
Located in Library / RBINS Staff Publications / Pending Duplicate Bibliography Entries
Article Reference D source code Taxonomy and systematics in biodiversity research
Located in Library / RBINS Staff Publications / Pending Duplicate Bibliography Entries
Article Reference chemical/x-molconn-Z Rotifers from Kalasin Province, Northeast Thailand, with notes on new and rare species
We report on a survey of rotifers from 30 habitats in Kalasin Province, Northeast Thailand, collected during Dec. 2001. One hundred and fifty species were identified. One of them, Lecane lungae sp. nov. is new to science, and two, L. opias (Harring and Myers), and L. stichoclysta Segers are new to the Oriental region and Thailand; the record of L. stichoclysta is the second record ever of the species after its description from Nigeria (Africa). In addition, we illustrate a remarkable morphological variant of Keratella cochlearis. These records, together with the new occurrences of other endemic rotifer species illustrate the remarkable diversity of the Thai rotifer fauna, and add to our knowledge of rotifer chorology.
Located in Library / RBINS Staff Publications / Pending Duplicate Bibliography Entries
Article Reference chemical/x-molconn-Z The future of freshwater biodiversity research: An introduction to the target review
Located in Library / RBINS Staff Publications / Pending Duplicate Bibliography Entries
Article Reference Tale of a sleeping beauty: A new and easily cultured model organism for experimental studies on bdelloid rotifers
We present the description of a new species of bdelloid rotifer, Adineta ricciae n. sp., which emerged from dry mud of Ryan's billabong, Victoria, Australia. Its conspicuous frontal eyes easily diagnose the species; it differs from A. oculata (Milne) by the position of the eyes and its general habitus. The animal came to our attention because it is exceptionally easy to culture, so that the species already is being used in diverse experimental studies utilising bdelloid rotifers as model organisms. © Springer 2005.
Located in Library / RBINS Staff Publications / Pending Duplicate Bibliography Entries