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Kenneth F. Higgins - One of the best experts on this subject based on the ideXlab platform.
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Patterns of prey use by lesser scaup Aythya affinis (Aves) and diet overlap with fishes during spring migration
Hydrobiologia, 2008Co-Authors: Kimberly A. Strand, Sharon N. Kahara, Steven R Chipps, Kenneth F. HigginsAbstract:Recent decline in the lesser scaup Aythya affinis population has been linked to changes in wetland conditions along their spring migration routes. In particular, the use of Amphipod prey by lesser scaup has declined in many regions of the upper Midwest U.S.A. and has been linked to expanded fisheries, although empirical data on diet overlap are lacking. To explore patterns of prey use by lesser scaup and diet overlap with fishes, we quantified diets of scaup and fishes during the 2003 and 2004 spring migration in eastern South Dakota, U.S.A. We compared diet overlap between lesser scaup and fishes collected from Twin Lakes, South Dakota—an important stopover location for spring-migrating scaup. Plant seeds occurred in >95% of lesser scaup diets ( n = 118) and represented an appreciable amount of consumed biomass (>70%). Gastropods, Amphipods, and chironomids were the most abundant invertebrate prey taxa and occurred in 29–34% of lesser scaup diets. Although relatively frequent, these taxa each contributed only 4–27% of the diet by weight. Percent dry mass of Amphipods, a preferred prey by lesser scaup, was low (4%) indicating that Amphipod availability may be reduced during spring migration. Analysis of fish diets showed that black bullhead Ameiurus melas and yellow perch Perca flavescens had the highest diet overlap with lesser scaup at 94% and 92%, respectively. Moreover, mean size of Amphipods and chironomids found in fish diets were significantly larger than that consumed by lesser scaup. Our findings support the notion that Amphipod use by spring-migrating lesser scaup has declined and that size-selective predation by fishes may influence prey availability for lesser scaup.
Just T Baylesempere - One of the best experts on this subject based on the ideXlab platform.
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changes in Amphipod crustacea assemblages associated with shallow water algal habitats invaded by caulerpa racemosa var cylindracea in the western mediterranean sea
Marine Environmental Research, 2008Co-Authors: Maite Vazquezluis, Pablo Sanchezjerez, Just T BaylesempereAbstract:The effects of the invasive species Caulerpa racemosa var. cylindracea (hereafter C. racemosa) on Amphipod assemblages associated with shallow-water rocky habitats were studied. Two habitats located along the SE Iberian Peninsula were compared; invaded and non-invaded. The results showed that growth of C. racemosa affects habitat structure, influencing the species composition and biomass of macroalgae, and detritus accumulation. In turn, such changes in habitat features affected the associated Amphipod assemblages with different ecological requirements. However, the species richness of Amphipods was relatively high in both habitats, while the species composition of Amphipods changed completely. For example, some species such as Ampithoe ramondi and Hyale schmidti did not colonize invaded habitats, while others such as Apocorophium acutum were favoured by the spread of C. racemosa. Habitat invasion by C. racemosa can have an important influence on biotic assemblages, modifying both habitat structure and the associated fauna, with unknown effects on the overall ecosystem.
Jean-claude Dauvin - One of the best experts on this subject based on the ideXlab platform.
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polychaete Amphipod ratios an approach to validating simple benthic indicators
Ecological Indicators, 2016Co-Authors: Jean-claude Dauvin, H. Andrade, Jose Antonio Delaossacarretero, Yoana Delpilarruso, R. RieraAbstract:Among the macro-invertebrates used for the assessment of soft-bottom communities, most polychaetes are classified as tolerant/opportunistic to pollution while Amphipods are considered as sensitive. These taxa have been used in several ecological indices, such as the simple abundance ratio between Polychaeta and Amphipoda or the Benthic Opportunist Annelids Amphipods (BO2A) index, to assess the Ecological Quality Status -EcoQs- of soft-bottom communities. In terms of Taxonomic Sufficiency (TS), the polychaete/Amphipod ratio (i.e. at the level of the class/order) has been proved to be effective in identifying major changes in benthic communities following disturbances. However, an underlying issue is to assess the acceptable TS limit value needed to state accurately the quality of the benthic environment. We tested three indices using 18 series of observations carried out in five north-eastern Atlantic and Mediterranean zones impacted by oil spills, oil and gas production, brine and urban sewage, harbours and aquaculture farms within impacted and control areas. Similar results to BO2A were obtained when limiting the TS at the level of Polychaete opportunistic families, which required a lower degree of taxonomic expertise, and classifying all Amphipods as sensitive taxa. In such a way that the EcoQs given by the BPOFA (Benthic Polychaete Opportunistic Families Amphipods) was very similar to those given by the BO2A (Benthic Opportunistic Annelids Amphipods).
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Amphipods are good bioindicators of the impact of oil spills on soft bottom macrobenthic communities
Marine Pollution Bulletin, 2000Co-Authors: J Gomez L Gesteira, Jean-claude DauvinAbstract:The Amoco Cadiz oil spill in 1978, and the Aegean Sea oil spill in 1992, affected soft-bottom communities, respectively from the Bay of Morlaix (western English Channel) and from the Ria de Ares and Betanzos in the north-western Iberian peninsula. These infralittoral communities on muddy fine sand showed similar species composition and structure and occurred in similar hydro-climatic conditions. The effects of the spills were identical in both areas with the disappearance of the Amphipods especially those from the Amphipod genus Ampelisca with a very low colonization of these species during the four years after the spill. The recovery rate of the Amphipods was slow but progressive. In such communities no proliferation of opportunistics was observed after the stress. In the sites, where polychaetes dominated before the spill, they remained dominant, whereas other sites showed very low total abundances during the two years after the spill due to the absence of compensation for the disappearance of these crustaceans. In fact, there was a very low impact of the spill on polychaetes, but a high one on Amphipods. In the future, it is suggested to focus monitoring after a spill only on a single Amphipod group proposed as a bioindicator for detecting the impact of pollution. A polychaete/Amphipod ratio is proposed to reflect temporal change of soft-bottom communities analogous to the nematode/copepod previously suggested for the meiobenthos. Detailed knowledge of the qualitative and quantitative structure of a benthic community is still needed in order to identify very precisely the effect of a pollution event.
Kimberly A. Strand - One of the best experts on this subject based on the ideXlab platform.
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Patterns of prey use by lesser scaup Aythya affinis (Aves) and diet overlap with fishes during spring migration
Hydrobiologia, 2008Co-Authors: Kimberly A. Strand, Sharon N. Kahara, Steven R Chipps, Kenneth F. HigginsAbstract:Recent decline in the lesser scaup Aythya affinis population has been linked to changes in wetland conditions along their spring migration routes. In particular, the use of Amphipod prey by lesser scaup has declined in many regions of the upper Midwest U.S.A. and has been linked to expanded fisheries, although empirical data on diet overlap are lacking. To explore patterns of prey use by lesser scaup and diet overlap with fishes, we quantified diets of scaup and fishes during the 2003 and 2004 spring migration in eastern South Dakota, U.S.A. We compared diet overlap between lesser scaup and fishes collected from Twin Lakes, South Dakota—an important stopover location for spring-migrating scaup. Plant seeds occurred in >95% of lesser scaup diets ( n = 118) and represented an appreciable amount of consumed biomass (>70%). Gastropods, Amphipods, and chironomids were the most abundant invertebrate prey taxa and occurred in 29–34% of lesser scaup diets. Although relatively frequent, these taxa each contributed only 4–27% of the diet by weight. Percent dry mass of Amphipods, a preferred prey by lesser scaup, was low (4%) indicating that Amphipod availability may be reduced during spring migration. Analysis of fish diets showed that black bullhead Ameiurus melas and yellow perch Perca flavescens had the highest diet overlap with lesser scaup at 94% and 92%, respectively. Moreover, mean size of Amphipods and chironomids found in fish diets were significantly larger than that consumed by lesser scaup. Our findings support the notion that Amphipod use by spring-migrating lesser scaup has declined and that size-selective predation by fishes may influence prey availability for lesser scaup.
Kim N Mouritsen - One of the best experts on this subject based on the ideXlab platform.
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Parasites on an intertidal Corophium-bed: factors determining the phenology of microphallid trematodes in the intermediate host populations of the mud-snail Hydrobia ulvae and the Amphipod Corophium volutator
Hydrobiologia, 1997Co-Authors: Kim N Mouritsen, Tomas Jensen, K. Thomas JensenAbstract:The phenology of microphallid trematodes within their intermediate hostpopulations has been studied on an intertidal mud flat. The parasites usethe mud snail Hydrobia ulvae and the infaunal Amphipod Corophium volutatoras first and secondary intermediate host, respectively. Migratory shorebirdsact as final hosts. Our results show a general trend of decline in thedensity of infected intermediate hosts during both spring and autumn, whichcould mainly be ascribed to shorebird predation. During summer the densityof both infected snails and infected Amphipods increased considerably, witha culmination in June within the snail population (1000 infectedm-^2 and in August within the Amphipod population (40 000infected m-^2. This time lag in parasite occurrence could berelated to (1) the development time of larval trematodes within the snails,(2) higher ambient temperatures in late summer increasing parasitetransmission between snails and Amphipods during this period, and (3) ageneral increase in the Corophium population during late summer. Fromsamples collected between 1990 and 1995 it is shown that microphallidtrematodes occasionally may give rise to mass mortality in the Amphipodpopulation. The prerequisites for such an event are a high parasiteprevalence within the first intermediate host population and unusually highambient temperatures, facilitating parasite transmission to the secondaryintermediate host, C. volutator.
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parasite transmission between soft bottom invertebrates temperature mediated infection rates and mortality in corophium volutator
Marine Ecology Progress Series, 1997Co-Authors: Kim N Mouritsen, Kurt JensenAbstract:Circumstantial evidence has suggested that marine mlcrophallid ti-ematodes using gastropods Hydrobia spp. as flrst lnterlnedlate hosts, Amphipods Corophlum spp. as second intermediate hosts, and various waterblrds as final hosts, may cause temperature-dependent epizootics and eventually local extinction of ~ntel-mediate host populations. Therefore, we examined experirnentally the impact of the microphallid trematode Mar~trenia subdolum on Corophluni volutator wlth special relerence to the influence of temperature, during the parasltes' transmission from s n a ~ l to Amphipod. Trematode infected snails and Amphipods were estabhshed togtlther in experimental aquaria at temperatures of 15, 2 2 and 24°C for 9 d. Amphipod surface activ~ty, survlvdl rate, parasite prevalence, lnfectioil rate, and paraslte dlstnbution both within and between amphlpod ~nt i~vlduals were recorded dunng , or at the end of, the experiment The snalls' shedding rate of larval ti-clnatodes as a function of temperature was also exam~ned . Increasing temperature resulted 111 higher Infection levels and parasite-induced mortality in the Amphipods, most Ilkely governed by a similar temperature-dependent emergence of larval trc'matodes from the snails. No transmission occurred at I j 'C , whereas at 24°C the paraslte prevalence approached 100",1 and the parasite-induced mortality exceeded 50%) in relation to controls As assessed by the transparency of the Amphipods' gills, infestation inflicted anaemia was the llkely mechanism behind the Increased surface activity observed among infected specimens. This paraslteinduced behavioural change niay facilitate transmission of infective stages to shorebird hosts feeding on C. volutator The results demonstrate that microphalhd trematodes are able to induce a significant additive mortality in C. volutator populatlons. The temperature mediated mortality emphasizes the potential significance of a density-~ndependent process in controlling the impact of parasltes on host organisms and thereby host population dynamics.