Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Effect of copper exposure on histamine concentrations in the marbled crayfish
    Soedarini, B. ; Klaver, L. ; Giesen, D. ; Roessink, I. ; Widianarko, B. ; Straalen, N.M. van; Gestel, C.A.M. van - \ 2013
    Animal Biology 63 (2013)2. - ISSN 1570-7555 - p. 139 - 147.
    metal bioaccumulation - accumulation - toxicity - metallothionein - hepatopancreas - crustacea - decapoda - kinetics - clarkii - shrimp
    Crustaceans can store excess copper in the hepatopancreas, an organ playing a role in digestive activity as well as in neurosecretory control. Here, we studied the effect of copper exposure on the level of histamine, an indicator of food spoilage in edibl
    Some lite it hot: the effect of temperature on brood development in the invasive crab Hemigrapsus takanoi (Decapoda: brachyura: Varunidae)
    Brink, A.M. van den; Godschalk, M. ; Smaal, A.C. ; Lindeboom, H.J. ; McLay, C.L. - \ 2013
    Journal of the Marine Biological Association of The United Kingdom 93 (2013)1. - ISSN 0025-3154 - p. 189 - 196.
    carcinus-maenas - green crab - shore crab - atlantic coast - sanguineus - grapsidae - hymenosomatidae - penicillatus - california - crustacea
    The duration of brood development in the introduced crab, Hemigrapsus takanoi in the Oosterschelde, The Netherlands, was compared at three different water temperatures. At 12, 18 and 24°C the females took an average of 32, 11 and 8 days respectively to lay eggs, which took 86, 28 and 18 days respectively to complete development. Five stages of development were identified, with each brood stage comprising a similar proportion of the duration time at different temperatures. The duration of each brood stage was also somewhat proportional to the number of females found carrying each brood stage in the field at the beginning of the breeding season. There appears to be a trigger for the breeding season in H. takanoi in the field at around 15°C above which ovary development begins. The results suggest that an increase in water temperature as a result of climate change may result in an increased net reproductive rate in H. takanoi due to earlier onset of the breeding season and increased number of broods per inter-moult period resulting in population growth. Increased temperatures may therefore lead to increased invasiveness of H. takanoi where it is already present, and range extension into locations where its establishment is currently excluded by unsuitable temperature
    Springstaarten in de opkweek en bij export van potplanten: Problematiek en inventarisatie mogelijke oplossingen
    Staaij, M. van der; Linden, A. van der; Grosman, A.H. - \ 2012
    Bleiswijk : Wageningen UR Glastuinbouw (Rapporten GTB 1210) - 30
    potplanten - crustacea - bestrijdingsmethoden - preventie - fytosanitaire maatregelen - exportbeperkingen - glastuinbouw - pot plants - crustacea - control methods - prevention - phytosanitary measures - export controls - greenhouse horticulture
    Springstaarten komen vrijwel altijd in de bodem voor en worden in het algemeen als niet schadelijke of zelfs nuttige organismen beschouwd. Ze voeden zich met schimmels, algen, mossen en dood organische materiaal en vormen voedsel voor bodemrovers, bijv. nuttige bodemroofmijten. In landbouwgewassen zoals katoen, aardappel en kool is aangetoond dat springstaarten de infectie door Rhizoctonia verminderen. In potplanten zijn springstaarten echter een toenemend probleem, zowel in de opkweek als bij de export. In eerste instantie gaat het om directe gewasschade. De schade door springstaarten is vrijwel altijd beperkt tot de teelt van uitgangsmateriaal, met name zaaigoed. In het zeer jonge groeistadium zijn de wortels gevoelig voor vraat door springstaarten. Secundair speelt daarbij mee dat bij grote plaagdruk springstaarten de bovenste laag grond omwoelen, waardoor (haar)worteltjes bloot komen te liggen en de kiemplantjes bedekt raken onder gronddeeltjes, waardoor ze achterblijven in groei of zelfs zover van de wortel afraken dat ze dood gaan.
    Temperature fluctuation, low salinity, water microflora: Risk factors for WSSV outbreaks in Penaeus monodon
    Tendencia, E. ; Verreth, J.A.J. - \ 2011
    Israeli Journal of Aquaculture-Bamidgeh 63 (2011). - ISSN 0792-156X - 7 p.
    white-spot-syndrome - syndrome-virus-infection - marsupenaeus-japonicus - litopenaeus-vannamei - immune-responses - shrimp - system - aquaculture - crustacea - disease
    White spot syndrome virus (WSSV) has been devastating the shrimp industry for almost a decade. This study compares water parameters, alkalinity, and microflora in three ponds on a farm on Negros Island (Philippines) during two production cycles where WSSV infection resulted in an outbreak in 2006 but not in 2005. The total bacterial count of the pond water in 2005 was about twice as high as in 2006. However, luminous bacterial counts were twice as high in 2006 than in 2005 and total presumptive Vibrio, as counted on Vibrio selective thiosulfate citrate bilesalt sucrose (TCBS) agar, was over ten times higher, with a greater percentage of green colonies. More green colonies might indicate a higher concentration of harmful Vibrio bacteria. Total alkalinity for both production cycles was within the normal range while temperature, salinity, pH, and dissolved oxygen varied and sometimes fell below or exceeded the acceptable range. In 2006, there were more instances during which the temperature fluctuated 3-4 degrees C within the period of 07: 00-17: 00, and salinity more often dropped below 15 ppt. Our survey suggests that WSSV outbreak are triggered by water temperature fluctuations of 3-4 degrees C, coupled with low salinity and a high presumptive Vibrio count.
    Local anthropogenic contamination affects the fecundity and reproductive success of an Arctic amphipod
    Bach, L. ; Fischer, A. ; Strand, J. - \ 2010
    Marine Ecology Progress Series 419 (2010). - ISSN 0171-8630 - p. 121 - 128.
    lysianassid amphipods - gammaridean amphipods - marine environments - intersex - bionomics - crustacea - responses - latitude - embryos - sea
    This study investigates whether adaptation to life in contaminated Arctic areas carries a cost for the populations in terms of reduced fecundity and reproductive success. The benthic amphipod, Orchomenella pinguis occurs in huge densities in both clean and contaminated sites. O. pinguis was collected at contaminated sites in an open fjord adjacent to Sisimiut, West Greenland, and at clean sites outside the fjord exposed to open waters. The broods of gravid females were analyzed for number of embryos, embryonic developmental stage and number of embryo abnormalities. Further, a sample from 3 of the sites was sexed and analyzed for intersex occurrence. The individuals collected at the most contaminated site had significantly higher fecundity (i.e. reproductive potential), but also higher frequency of embryo aberrations resulting in lower fertility (i.e. actual reproductive success) compared to clean site individuals. These results indicated a cost of living in highly contaminated environments in terms of reduced reproductive success. This study confirms the potential of the benthic amphipod O. pinguis as a bioindicator for assessments of reproductive effects of contaminants in the Arctic marine environment.
    Identifying hybridizing taxa within the Daphnia longispina species complex: a comparison of genetic methods and phenotypic approaches
    Dlouha, S. ; Thielsch, A. ; Kraus, R.H.S. ; Seda, J. ; Schwenk, K. ; Petrusek, S. - \ 2010
    Hydrobiologia 643 (2010)1. - ISSN 0018-8158 - p. 107 - 122.
    interspecific hybridization - cyclomorphic daphnia - sexual reproduction - concerted evolution - european daphnia - galeata complex - cladocera - crustacea - differentiation - mechanism
    Daphnia galeata Sars, D. longispina O. F. Muller and D. cucullata Sars (Crustacea: Cladocera) are closely related species which often produce interspecific hybrids in natural populations. Several marker systems are available for taxon determination in this hybridizing complex, but their performance and reliability has not been systematically assessed. We compared results from identifications by three molecular methods. More than 1,200 individuals from 10 localities in the Czech Republic were identified as parental species or hybrids by allozyme electrophoresis and the analysis of the restriction fragment length polymorphism of the internal transcribed spacer (ITS-RFLP); over 440 of them were additionally analyzed and identified by 12 microsatellite loci. Identification by microsatellite markers corresponded well with allozyme analyses. However, consistent discrepancies between ITS-RFLP and other markers were observed in two out of 10 studied localities. Although some marker discrepancies may have been caused by occasional recent introgression, consistent deviations between ITS-RFLP and other markers suggest a long-term maintenance of introgressed alleles. These results warn against its use as a sole identification method in field studies. Additionally, we quantitatively evaluated the discriminatory power of geometric morphometric (elliptic Fourier) analysis of body shapes based on photos of over 1,300 individuals pre-classified by allozyme markers. Furthermore, a randomly selected subset of 240 individuals was independently determined from photos by several experts. Despite a tendency for morphological divergence among parental Daphnia species, some taxa (especially D. galeata, D. longispina, and their hybrids) substantially overlapped in their body shapes. This was reflected in different determination success for particular species and hybrids in discriminant analysis based on shape data as well as from photographs
    Effects of animal starvation on the sensitivity of the freshwater amphipod Gammarus pulex to cadmium
    Alonso, A. ; Garcia-Johansson, V. ; Lange, H.J. de; Peeters, E.T.H.M. - \ 2010
    Chemistry and Ecology 26 (2010)3. - ISSN 0275-7540 - p. 233 - 242.
    seasonal food limitation - unionized ammonia - stream invertebrates - sublethal responses - pulsed exposure - toxicity - crustacea - survival - metals - tests
    Populations of amphipods experience different food availabilities during the year. This may alter their sensitivities to toxicants. However, there is scarce information about the effects of starvation on the tolerance to pollutants, and no data are available for the species Gammarus pulex. Our aim was to evaluate the effects of different levels of starvation on the short-term mortality of G. pulex on exposure to cadmium. Four levels of starvation (0, 3, 5 and 7 days without food) were assessed using two exposure modes: semi-static (4 days exposure to 0.10, 0.20 and 0.35 mg Cd·L-1) and two pulses (2 and 6 h) of 2 mg Cd·L-1. LT50 and peLT50 values (post exposure) were calculated for each concentration and pulse, respectively. Our results show that starvation modifies the sensitivity of G. pulex. In general, at the lowest cadmium concentration (0.10 mg Cd·L-1) less-starved animals in semi-static exposure showed higher sensitivity to cadmium than more-starved animals. This trend was reversed for the highest cadmium exposure. Non-starved animals were more sensitive to cadmium applied in a short pulse than starved animals. Because natural populations are exposed to different food availability, starvation status has to be taken into account to assess the risk of toxicants
    Contrasting sensitivities to toxicants of the freshwater amphipods Gammarus pulex and G. fossarum
    Alonso, A. ; Lange, H.J. de; Peeters, E.T.H.M. - \ 2010
    Ecotoxicology 19 (2010)1. - ISSN 0963-9292 - p. 133 - 140.
    asellus-aquaticus l - behavioral-responses - unionized ammonia - feeding-activity - toxicity tests - life-stages - crustacea - cadmium - invertebrates - metals
    Amphipods are an important component of freshwater ecosystems. They are very often used in ecotoxicology, particularly the freshwater amphipod Gammarus pulex. However, there is scarce information on the sensitivity to toxicants of other species within the genus Gammarus. The present study aims to: (1) to compare sensitivities to ivermectin and cadmium between two species of freshwater amphipods (G. pulex and G. fossarum); (2) to compare sensitivities to these toxicants between juveniles and adults within each species; and (3) to assess whether the sensitivity to toxicants of these co-generic species is related with the wideness of their natural distribution area. Eight independent short-term bioassays (96 h) were conducted to assess sensitivity for ivermectin and cadmium for juvenile and adult life stages for each species. The LC50 (mortality) and EC50 (mortality plus immobility) were calculated to 48 and 96 h of continuous exposure. Our results showed that G. pulex was less tolerant to ivermectin than G. fossarum, the reverse being true for cadmium. In general, juveniles of both species were less tolerant to cadmium than adults. In the case of ivermectin, only for G. fossarum EC50 values were different between life stages. These results suggest that the risk assessment of toxicants to freshwater amphipods should include bioassays with the most sensitive species and life stage
    Long-Term Effects of Ammonia on the Behavioral Activity of the Aquatic Snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca)
    Alonso, A. ; Camargo, J.A. - \ 2009
    Archives of Environmental Contamination and Toxicology 56 (2009)4. - ISSN 0090-4341 - p. 796 - 802.
    fresh-water invertebrates - chronic toxicity - gammarus-pulex - unionized ammonia - cadmium exposure - responses - crustacea - survival - mussels - biomonitor
    An appropriate approach to assess the effect of toxicants on aquatic animals is to monitor behavioral endpoints, as they are a link between physiological and ecological processes. A group that can be exposed long-term to low toxic concentrations is benthic macroinvertebrates, as their mobility in aquatic ecosystems is relatively limited. Therefore, the study of behavioral long-term effects in this group is suitable from an ecological point of view, as behavioral effects can appear before mortality. During the last decades there has been an increase in ammonia concentrations in freshwater ecosystems, threatening aquatic animals. The present study focuses on the long-term effects (40 days) of nonionized ammonia on the behavioral activity of the aquatic snail Potamopyrgus antipodarum. One control and three ammonia concentrations (0.02, 0.07, and 0.13 mg N-NH3/L) were used in triplicate, and the activity of snails (as mean time to start normal movement) and immobility were recorded for each treatment after 0, 10, 20, 30, and 40 days of continuous exposure to nonionized ammonia. The results show that P. antipodarum presented a high tolerance to lethal long-term effects of nonionized ammonia, as no animal died during the bioassay. However, the behavioral activity of snails was a very sensitivity endpoint, as a mean nonionized ammonia concentration of 0.07 mg N-NH3/L affected P. antipodarum. The results are discussed and compared with the available literature on long-term effects of ammonia on freshwater macroinvertebrates. Additionally, the ammonia water quality criteria, NOECs, LOECs, and long-term LCs are discussed on the basis of the current available data for freshwater macroinvertebrates.
    Development of a feeding behavioural bioassay using the freshwater amphipod Gammarus pulex and the Multispecies Freshwater Biomonitor.
    Alonso, A. ; Lange, H.J. de; Peeters, E.T.H.M. - \ 2009
    Chemosphere 75 (2009)3. - ISSN 0045-6535 - p. 341 - 346.
    acid-mine drainage - asellus-aquaticus - unionized ammonia - growth assay - responses - crustacea - toxicity - invertebrates - survival - cadmium
    The present study reports the development of a feeding behavioural bioassay using the Multispecies Freshwater Biomonitor (MFB). This device is based on the quadruple impedance conversion technique to record online different behaviours of animals. Animal movements in the water generate specific frequencies, and the MFB can estimate the percentage of time producing each frequency (from 0.5 to 8.5 Hz) by means of a stepwise discrete Fourier transformation. Two feeding behavioural bioassays were conducted in order to know the frequencies related to feeding behaviour of the freshwater amphipod Gammarus pulex. The first bioassay assessed the effects of food presence in the amphipod behaviour. The second bioassay assessed the effects of cadmium on the feeding activity (measured as leaf weight loss) and behaviour (swimming, ventilation, and feeding recorded through the MFB) of G. pulex in order to check the suitability of the developed method. The results of the first bioassay showed that the frequencies ranging from 3.0 to 4.5 Hz were highly correlated with feeding activity, especially 3.5 and 4.0 Hz. In the second bioassay, we found that cadmium reduced feeding and ventilation behaviours. Our study showed that the MFB can be used to record the feeding behaviour of G. pulex exposed to toxicants. The developed feeding behavioural bioassay allows an accurate and automatic assessment of several endpoints, including feeding, swimming and ventilation. However, the study of the complex behaviour of G. pulex using the MFB needs further research, since some behaviours seem to generate similar frequencies
    Variation in the behavior of the amphipod Gammarus pulex
    Peeters, E.T.H.M. ; Lange, H.J. de; Lürling, M.F.L.L.W. - \ 2009
    Human and Ecological Risk Assessment 15 (2009)1. - ISSN 1080-7039 - p. 41 - 52.
    trout salmo-trutta - impedance conversion - acute toxicity - crustacea - stream - growth - drift - invertebrates - individuals - precopula
    Variation in the locomotion behavior of Gammarus pulex was studied using the Multispecies Freshwater Biomonitor®. Behavior was recorded individually under a 12:12 h light:dark cycle for a period of 7 d during which the amphipods were not fed. Gammarids behaved differently during the first 7 h in the laboratory chambers. Most specimens were active and decreased their activity but some were relatively inactive after the start of the experiment and increased their locomotion. At least 2 h are needed by G. pulex to accustom to the conditions. No significant relationships existed between type of behavior during the acclimation period or acclimation time and gender or length of the gammarids. There was a large variation in time spent on locomotion during the first night. In general, males were significantly more active than females. Within males, a distinction can be made between very active and less active specimens. The 7-d observation period showed that only 70% of the specimens demonstrated a clear day-night rhythm with higher activity during the night. Unexpectedly, approximately 10% of the specimens were more active during daytime. Furthermore, in this study locomotion became relatively stable only after 4 d. Inter-individual variation in behavior must be taken into account when using behavior as an endpoint in ecotoxicological bioassays.
    Ameliorating Effect of Chloride on Nitrite Toxicity to Freshwater Invertebrates with Different Physiology: a Comparative Study Between Amphipods and Planarians
    Alonso, A. ; Camargo, J.A. - \ 2008
    Archives of Environmental Contamination and Toxicology 54 (2008)2. - ISSN 0090-4341 - p. 259 - 265.
    ammonia toxicity - aquatic animals - sensitivity - crustacea - nitrate - larvae - gammaridae - sediments - survival - sodium
    High nitrite concentrations in freshwater ecosystems may cause toxicity to aquatic animals. These living organisms can take nitrite up from water through their chloride cells, subsequently suffering oxidation of their respiratory pigments (hemoglobin, hemocyanin). Because NO2¿ and Cl¿ ions compete for the same active transport site, elevated chloride concentrations in the aquatic environment have the potential of reducing nitrite toxicity. Although this ameliorating effect is well documented in fish, it has been largely ignored in wild freshwater invertebrates. The aim of this study was to compare the ameliorating effect of chloride on nitrite toxicity to two species of freshwater invertebrates differing in physiology: Eulimnogammarus toletanus (amphipods) and Polycelis felina (planarians). The former species presents gills (with chloride cells) and respiratory pigments, whereas in the latter species these are absent. Test animals were exposed in triplicate for 168 h to a single nitrite concentration (5 ppm NO2-N for E. toletanus and 100 ppm NO2-N for P. felina) at four different environmental chloride concentrations (27.8, 58.3, 85.3, and 108.0 ppm Cl¿). The number of dead animals and the number of affected individuals (i.e., number of dead plus inactive invertebrates) were monitored every day. LT50 (lethal time) and ET50 (effective time) were estimated for each species and each chloride concentration. LT50 and ET50 values increased with increases in the environmental chloride concentration, mainly in amphipods. Results clearly show that the ameliorating effect of chloride on nitrite toxicity was more significant in amphipods than in planarians, likely because of the absence of gills (with chloride cells) and respiratory pigments in P. felina. Additionally, this comparative study indicates that the ecological risk assessment of nitrite in freshwater ecosystems should take into account not only the most sensitive and key species in the communities, but also chloride levels in the aquatic environment
    An individual-based approach to model spatial population dynamics of invertebrates in aquatic ecosystems after pesticide contamination
    Brink, P.J. van den; Verboom, J. ; Baveco, J.M. ; Heimbach, F. - \ 2007
    Environmental Toxicology and Chemistry 26 (2007)10. - ISSN 0730-7268 - p. 2226 - 2236.
    isopod asellus-aquaticus - life-history - crustacea - growth - stream - water - lake
    In the present study we present a population model (Metapopulation model for Assessing Spatial and Temporal Effects of Pesticides [MASTEP]) describing the effects on and recovery of the waterlouse Asellus aquaticus after exposure to a fast-acting, nonpersistent insecticide as a result of spray drift in pond, ditch, and stream scenarios. The model used the spatial and temporal distribution of the exposure in different treatment conditions as an input parameter. A dose¿response relation derived from a hypothetical mesocosm study was used to link the exposure with the effects. The modeled landscape was represented as a lattice of 1- by 1-m cells. The model included processes of mortality of A. aquaticus, life history, random walk between cells, density dependence of population regulation, and, in the case of the stream scenario, medium-distance drift of A. aquaticus due to flow. All parameter estimates were based on expert judgment and the results of a thorough review of published information on the ecology of A. aquaticus. In the treated part of the water body, the ditch scenario proved to be the worst-case situation, due to the absence of drift of A. aquaticus. Effects in the pond scenario were smaller because the pond was exposed from one side, allowing migration from the other, less contaminated side. The results of the stream scenario showed the importance of including drift for the population recovery in the 100-m stretch of the stream that was treated. It should be noted, however, that the inclusion of drift had a negligible impact on numbers in the stream as a whole (600 m).
    First insights into the biodiversity and biogeography of the Southern Ocean deep sea
    Brandt, A. ; Gooday, A.J. ; Brandao, S.N. ; Mesel, I.G. de - \ 2007
    Nature 447 (2007)7142. - ISSN 0028-0836 - p. 307 - 311.
    species-diversity - benthic diversity - weddell sea - ecology - origin - scale - foraminifera - antarctica - peracarida - crustacea
    Shallow marine benthic communities around Antarctica show high levels of endemism, gigantism, slow growth, longevity and late maturity, as well as adaptive radiations that have generated considerable biodiversity in some taxa. The deeper parts of the Southern Ocean exhibit some unique environmental features, including a very deep continental shelf and a weakly stratified water column, and are the source for much of the deep water in the world ocean. These features suggest that deep-sea faunas around the Antarctic may be related both to adjacent shelf communities and to those in other oceans. Unlike shallow-water Antarctic benthic communities, however, little is known about life in this vast deep-sea region. Here, we report new data from recent sampling expeditions in the deep Weddell Sea and adjacent areas (748-6,348 m water depth) that reveal high levels of new biodiversity; for example, 674 isopods species, of which 585 were new to science. Bathymetric and biogeographic trends varied between taxa. In groups such as the isopods and polychaetes, slope assemblages included species that have invaded from the shelf. In other taxa, the shelf and slope assemblages were more distinct. Abyssal faunas tended to have stronger links to other oceans, particularly the Atlantic, but mainly in taxa with good dispersal capabilities, such as the Foraminifera. The isopods, ostracods and nematodes, which are poor dispersers, include many species currently known only from the Southern Ocean. Our findings challenge suggestions that deep-sea diversity is depressed in the Southern Ocean and provide a basis for exploring the evolutionary significance of the varied biogeographic patterns observed in this remote environment.
    Life and work of Dr. Johannes Govertus de Man (1850-1930)
    Karssen, G. - \ 2006
    Leiden : Brill - ISBN 9789004149694 - 119
    nematoda - crustacea - decapoda - taxonomie - beschrijvingen - biografieën - nematoda - crustacea - decapoda - taxonomy - descriptions - biographies
    This book describes the life and work of Dr. Johannes Govertus de Man (1850-1930), a remarkable Dutch invertebrate zoologist. J.G. de Man worked on the systematics of both the Crustacea, in particular on Decapoda (i.e. crabs, crayfish, lobsters and shrimps), and the microscopically Nematoda or roundworms. The biographic part describes his years of childhood and youth, student days and the time he was working at the National Museum of Natural History, Leiden, the Netherlands and the period after he resigned at the museum. Within appendices his publications, described Crustacea, Nematoda and other taxa, species named after de Man and the de Man archive is presented. A selection of his drawings and a CD-ROM with his 1884 Nematoda monography is included.
    Real-time automated measurement of Xenopus leavis tadpole behavior and behavioral response following triphenyltin exposure using the multispecies freshwater biomonitor (MFB)
    Schriks, M. ; Hoorn, M.K. van; Faassen, E.J. ; Dam, J.W. van; Murk, A.J. - \ 2006
    Aquatic Toxicology 77 (2006)3. - ISSN 0166-445X - p. 298 - 305.
    chemical cues - differential predation - feeding-behavior - waste-water - avoidance - larval - fish - biomarkers - crustacea - patterns
    The present study examines whether behavior of Xenopus laevis tadpoles, when measured with the multispecies freshwater biomonitor (MFB), can be a sensitive and practical parameter for quantification of behavioral effects induced by toxic compounds. The MFB system is capable of automated simultaneous recording and integration of different types of movement over time. Basic tadpole behavior was studied under standard ambient temperature and colder conditions. At lower temperatures the time spent on low frequency behavior such as swimming and ventilation decreased, while at higher frequency movements associated with subtle tail tip oscillations it increased. Changes in behavior were also studied during the process of metamorphosis when both the morphology and physiology of tadpoles change. In the course of metamorphosis the tadpoles decreased the time spent on swimming and increased tail tip oscillations, especially in the period shortly before and during metamorphic climax. Additional experiments were performed to investigate whether the MFB could be used to quantify behavioral effects of exposure to a toxic compound. A 48h exposure to a sublethal concentration of 1.25mugL(-1) triphenyltin (TPT) significantly increased low frequency behavior, whereas 5mugL(-1) TPT significantly reduced this type of behavior while the number of periods of total inactivity increased. One week after transferring the animals to clean water, registered behavior of tadpoles in the highest TPT group (5mugL(-1)) was normal again for this developmental stage. The results show that the MFB can be used as a new tool for automated registration of sublethal toxic effects on tadpole behavior including recovery.
    Attraction of the amphipod Gammarus pulex to water-borne cues of food
    Lange, H.J. de; Lürling, M.F.L.L.W. ; Borne, J.J.G.C. van den; Peeters, E.T.H.M. - \ 2005
    Hydrobiologia 544 (2005)1. - ISSN 0018-8158 - p. 19 - 25.
    released chemical cues - asellus-aquaticus - crustacea - growth - conspecifics - predators - stimuli - minus - diet - pseudolimnaeus
    We examined the ability of the amphipod Gammarus pulex to detect chemical cues released from potential food sources. Therefore, response of G. pulex to chemical cues from food was tested in paired-choice laboratory experiments. Comparisons were made between artificial and natural leaves, with and without the importance of aufwuchs, and with different components of the aufwuchs community. Our study demonstrated that G. pulex actively chose its food and that G. pulex is most strongly attracted to the aufwuchs on discs rather than to the leaf itself. Fungi and bacteria are more important in the food selection process than algae probably because fungal and bacterial cues are more specific cues for decaying leaves than algal cues, since algae also grow on mineral substrates and then do not contribute to leaf decomposition
    Responses in sediment bioassays used in the Netherlands: can observed toxicity be explained by routinely monitored priority pollutants?
    Lahr, J. ; Maas-Diepeveen, J.L. ; Stuijfzand, S.C. ; Leonards, P.E.G. ; Drueke, J.M. ; Luecker, S. ; Espeldoorn, A. - \ 2003
    Water Research 37 (2003)8. - ISSN 0043-1354 - p. 1691 - 1710.
    biotesten - sediment - toxiciteit - monitoring - verontreinigende stoffen - delta's - nederland - waterverontreiniging - waterbodems - rijn - maas - bioassays - sediment - toxicity - monitoring - pollutants - deltas - netherlands - water pollution - water bottoms - river rhine - river meuse - quality criteria - daphnia-magna - rhine delta - water - tests - microcontaminants - fractionation - crustacea - chemicals - organisms
    In order to identify the cause of toxicity in sediments and suspended matter, a large number of samples with different degrees of contamination was taken at various locations in The Netherlands. Standard acute bioassays were carried out with the bacterium Vibrio fischeri, the rotifer Brachionus calyciflorus and the anostracan Thamnocephalus platyurus. Chronic standard tests were performed using the water flea Daphnia magna and larvae of the midge Chironomus riparius. Some novel bioassays were performed as well. Most toxic effects observed in standard bioassays with sediments from polluted sediments (class 3 and 4 on a scale of 0¿4 according to the Dutch criteria) could be partly explained by toxic concentrations of known persistent priority pollutants, mainly heavy metals and occasionally polycyclic aromatic hydrocarbons. In some of the samples, ammonia toxicity was a confounding factor during testing. Suspended matter from the Meuse river at Eijsden, which may be considered as `new' sediment (pollution class 2), was moderately to highly toxic in almost all bioassays. This could have been associated with a combination of heavy metals, PAHs and ammonia. At two locations from the Lake IJssel area with no apparent persistent pollution, moderate and strong effects were nonetheless observed in invertebrate tests. This might have been due to agricultural run-off of pesticides, which are not routinely measured in sediments. A few effects on V. fischeri in canals and a small stream could not be explained with standard chemical analysis, but seemed associated with the outlets of sewage water treatment plants and industrial effluents. Additional chemical analysis of pore water samples from five selected sediments yielded more identified substances such as phtalates, decanes, cosanes and fragrances, but it was estimated that their contribution to the effects observed on V. fischeri, D. magna and C. riparius was negligible.
    Haemocytic defence in black tiger shrimp (Penaeus monodon)
    Braak, K. van de - \ 2002
    Wageningen University. Promotor(en): E.A. Huisman; W.B. van Muiswinkel; W.P.W. van der Knaap; J.H.W.M. Rombout. - S.l. : S.n. - ISBN 9789058086518 - 159
    penaeus monodon - crustacea - garnalen - immuunsysteem - immuniteitsreactie - immuniteit - verdedigingsmechanismen - via de cel overgebrachte immuniteit - rode bloedcellen - hemolymfe - monoclonale antilichamen - experimentele infectie - infectieziekten - garnalenteelt - penaeus monodon - crustacea - shrimps - immune system - immune response - immunity - defence mechanisms - cell mediated immunity - haemocytes - haemolymph - monoclonal antibodies - experimental infection - infectious diseases - shrimp culture

    Tropical shrimp culture is one of the fastest growing aquaculture sectors in the world. Since this production sector is highly affected by infectious pathogens, disease control is nowadays a priority. Effective prevention methods can be developed more efficiently when quantitative assays for the evaluation and monitoring of the health status of shrimp are available. The defence mechanisms of crustaceans are poorly understood, but knowledge about these is a prerequisite for the development of such health parameters. Therefore, the aim of this thesis was to obtain a better understanding of the defence system of the major cultured shrimp species in the world, Penaeus monodon . The present study emphasised the cellular components of the circulatory system, which play a central role in the haemolymph defence, i.e. the haemocytes.

    To study the usefulness of haemolymph for shrimp health assessment, several cellular and humoral characteristics of P. monodon were determined after haemolymph sampling from the ventral part of the haemocoel (chapter 2). Among other things, five different haemocyte types were distinguished by light microscopy, while electron microscopy revealed granular cells, semigranular cells and hyaline cells. It was concluded that haemolymph characterisation might be a useful tool for health estimation of P. monodon , but that standardisation of the techniques is a prerequisite.

    The use of monoclonal antibodies (mAbs) was proposed as a potential approach for the characterisation of haemocytes. Therefore, a set of mAbs specific for P. monodon haemocytes was produced by immunising mice with haemocyte membrane lysates (chapter 3). Four mAbs (WSH 6, WSH 7, WSH 8 and WSH 16) were selected and extensively characterised. For all mAbs, differences in amount and intensity of the labelling were found between immediately fixed haemocytes and non-fixed cells that were kept in Alsever's solution (AS, an anticoagulant which reduces haemocyte activation) and kept in L15 cell culture medium. WSH 6 reacted with the cell membranes of all fixed haemocytes, while WSH 7 and WSH 16 reacted with the cell membranes of the majority of fixed haemocytes. The membrane labelling appeared to decrease when cells were kept in L15 medium. WSH 8 did not react with the haemocyte membranes. All mAbs reacted with some granules, mainly present in the hyaline cells, when the haemocytes were immediately fixed. When non-fixed cells were kept in AS or in L15 medium, positive granules were also observed in semigranular and granular haemocytes as well as in the largest granules of a fourth cell type, that contains many granules of different sizes and electron densities. Immuno-reactive extracellular fibrous material could be observed when cells were kept in L15 medium. The change in staining pattern was extreme for WSH 8, somewhat less for WSH 6 and WSH 7 and lowest for WSH 16. Double labelling revealed that all mAbs showed a different staining pattern on membranes as well as on granules. WSH 16 also showed labelling in cytoplasmic vesicles, as well as in haemolymph plasma on histological sections. The hypothesis was put forward that immuno-reactive molecules recognised by these mAbs, were related to haemocyte activation factors and that the mAbs could be used in studying haemocyte differentiation, behaviour and function in P. monodon shrimp. Later on, WSH 8 indeed proved suitable for this in immuno-histochemical studies.

    A better characterisation of the immuno-reactive molecules would support the interpretation of the results. In order to investigate whether the mAbs reacted with well-conserved molecules and with haemocytes in animals with molecules that were better characterised than those of P. monodon , a comparative study was carried out (chapter 4). The mAbs also reacted on haemocyte monolayers of the freshwater shrimp Macrobrachium rosenbergii and the two freshwater crayfish Procambarus clarkii and Pacifastacus leniusculus . Immuno-labelling on haemolymph monolayers of the terrestrial isopod crustacean Porcellio scaber (woodlouse) and on coelomic fluid of the annelid Lumbricus terrestris (earthworm) showed partial reactivity. Immuno-reactivity was not observed on haemolymph monolayers of the insect Spodoptera exigua (Florida moth) and the mollusc Lymnaea stagnalis (pond snail), or on blood cell monolayers of the freshwater fish Cyprinus carpio (carp) and of human. On histological sections of M. rosenbergii and P. clarkii , mAb labelling was observed on the haemolymph plasma and on a proportion of the haemocytes. This comparative study showed reactivity of the mAbs in a wide range of crustaceans and related animals and suggests that well conserved molecules were recognised, which may indicate functional importance. Later on, molecules of P. leniusculus that reacted with WSH 6 were better characterised and it was indicated that this molecule could be clotting protein or filamin, which both could be involved in coagulation processes. Unfortunately, the immuno-reactive molecules of P. monodon with WSH 8 could not be characterised further.

    The circulating haemocytes of crustaceans are generally divided into hyaline, semigranular or granular cells, however, this classification is still ambiguous. Not much is known about haemocyte production in penaeid shrimp, but for a better haemocyte classification it is useful to establish how these cells are produced and mature. In order to clarify this, the localisation and (ultra)structure of the haematopoietic tissue and its relation with the circulating haemocytes were studied in chapter 5. The haematopoietic tissue is located in many lobules dispersed in different areas in the cephalothorax, mainly at the dorsal side of the stomach and at the base of the maxillipeds. In order to study the haemocyte production and maturation, shrimp were either injected with LPS, while mitosis was inhibited by vinblastine, or were repeatedly sampled for haemolymph. The presumed precursor cells in the haematopoietic tissue were located towards the exterior of the lobules and maturing young haemocytes towards the inner part, where they can be released into the haemal lacunae. It was proposed that the presumed young haemocytes were generally known as the hyaline cells. Moreover, a new model was proposed where the hyaline cells gave rise to two haemocytic developmental series, i.e., the large- and small-granular cell line. In addition, indications were found that the granular cells of at least the large-granular cell line mature and accumulate in the connective tissue and are easily released into the haemolymph. Light and electron microscopical observations supported the regulation of the haemocyte populations in the circulation by (stored) haemocytes from the connective tissue.

    In order to investigate the clearance reaction of P. monodon haemocytes live Vibrio anguillarum bacteria were injected and the shrimp were periodically sampled (chapter 6). Immuno-double staining analysis with specific antisera against the haemocyte granules and bacteria showed that many haemocytes encapsulated the bacteria at the site of injection. Furthermore, a rapid decrease of live circulating bacteria was detected in the haemolymph. Bacterial clearance in the haemolymph was induced by humoral factors, as observed by agglutinated bacteria, and followed by uptake in different places in the body. Bacteria mainly accumulated in the lymphoid organ, where they, or their degradation products, could be detected for at least seven days after injection. The lymphoid organ consists of folded tubules with a central haemal lumen and a wall, layered with cells. The haemolymph, including the antigens, seemed to migrate from the central tubular lumen through the wall, where the bacteria are arrested and their degradation is started. The lymphoid organ of penaeids is also poorly studied. Electron microscopy of the lymphoid organ revealed the presence of many phagocytic cells that morphologically resemble small-granular haemocytes. It was proposed that haemocytes settle in the tubule walls before they phagocytose. Observations from the present study are similar to clearance mechanisms in the hepatic haemolymph vessels in most decapod crustaceans that do not possess a lymphoid organ.

    Immuno-staining suggested that many of the haemocytes degranulate in the lymphoid organ, producing a layer of fibrous material in the outer tubule wall. These findings might contribute to the reduced haemocyte concentration in the haemolymph of diseased animals or following injection of foreign material. It is proposed that the lymphoid organ is a filter for virtually all foreign material encountered in the haemolymph. Haemocyte degranulation in the lymphoid organ tubule walls could contribute to the filtering capacity of this organ.

    The experimental shrimp appeared to contain many lymphoid organ spheroids, where bacterial antigens were finally also observed. It is proposed that the spheroids have a degradation function for both bacterial and viral material, and that their presence is primarily related to the history of the infectious burden of the shrimp.

    White spot syndrome virus (WSSV) is the pathogen that is a major cause of mortality in shrimp culture in the past decade. In contrast to the extensive study of the morphology and genome structure of the viral pathogen, the defence reaction of the host during WSSV infection is hardly studied. Therefore, the haemocyte response upon experimental WSSV infection was examined in P. monodon shrimp (chapter 7). A strong decline in free circulating haemocytes was detected during severe WSSV infection. The combination of in situ hybridisation with a specific DNA probe to WSSV and immuno-histochemistry with a specific antibody against haemocyte granules was carried out on tissue sections. Haemocytic reactions have never been reported in chronic or acute viral infections in shrimp, but the present results showed that many haemocytes leave the circulation and migrate to tissues where many virus-infected cells are present. However, a subsequent response to the virus-infected cells was not detected. During virus infection, the number of cells in the haematopoietic tissue was also reduced. Moreover, it was suggested that many haemocytes degranulated in the lymphoid organ, producing a similar but more obvious layer of fibrous material in the outer tubule wall than after bacterial injection.

    The obtained results are summarised and discussed in chapter 8. Furthermore, the results described in chapters 6 and 7 were used to refine the proposed model of chapter 5. The haemocytes of the small-granular cell line are suggested to mature and carry out their function in the lymphoid organ. The results of the present research emphasise the rapid activation of the haemocytes after stimulation of the animal and illustrate several relevant functions of those cells. The present knowledge provides reliable grounds for further discussions about production, maturation and activation of the haemocytes in penaeid shrimp and possibly also in related animals like other shrimp species, crayfish, lobsters and crabs. Knowledge of the functioning of the defence system is of extreme importance since stimulation of this system is considered as a potential intervention strategy in shrimp culture to overcome the infectious diseases.

    De internationale conferentie voor schaal- en schelpdieren, Jersey 1984 : beknopt verslag
    Davidse, W.P. - \ 1984
    Den Haag : L.E.I. (Mededeling / Afdeling Visserij. Landbouw-Economisch Instituut no. 309) - 33
    mollusca - schaaldieren - mossels - oesters - molluskenteelt - schaal- en schelpdierenteelt - crustacea - handel - mollusca - shellfish - mussels - oysters - mollusc culture - shellfish culture - crustacea - trade
    Een beknopt verslag van de lezingen over produktie, handel en verwerking van schaal- en schelpdieren. De meeste aandacht ging daarbij uit naar de (grote) garnaal, doch ook schelpdieren als mossels en oesters kregen ruime aandacht, zowel tijdens het officiele als tijdens het informele gedeelte van het congres. De publikatie bevat ook nog een beschrijving van het kweekproces bij Guernsey Sea Farms. Dit is een bedrijf voor het winnen en opkweken van oesters (hatchery/nursery), dat door deelnemers aan de conferentie werd bezocht
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