Chidi Onyema Egbeocha, Sorayya Malek, C. U. Emenike, P. Milow
Ingestion of microplastics by marine organisms is a common occurrence in marine ecosystems, but the experimental demonstration of the effects of ingested microplastics on marine organisms has only recently become an important subject of research. In this review, the ingestion of microplastics by marine organisms, its attendant potential consequences and specific hypothetical questions for further studies are discussed. The formation of heteroaggregates in the gut of prey organisms may delay microplastic clearance, potentially increasing the chances of microplastic trophic transfer to predators. Also, the survival and energetics of keystone species at lower trophic levels are negatively affected by ingestion of microplastics, thereby raising questions about the transfer of energy and nutrients to organisms at higher trophic levels. Further, since microplastics are able to adsorb and concentrate organic pollutants up to 1 million times more than the pollutant concentration in ambient waters, the ingestion of such small plastic fragments is, a probable route for the entrance and biomagnification of toxic chemicals in the marine food web. However, the equilibrium state between pollutant concentration in marine organisms and that of surrounding waters makes it unclear whether the ingestion of microplastics actually increases the pollutant load of organisms. Finally, microplastic ingestion can cause endocrine disorders in adult fish, which could result in neoplasia via epigenetic programming. Therefore, microplastic pollution may be a contributory cause of increased incidents of neoplasia in marine animals. The amount of microplastics in marine waters will steadily rise, and questions about their impact on marine ecosystems will linger.
{"title":"Feasting on microplastics: ingestion by and effects on marine organisms","authors":"Chidi Onyema Egbeocha, Sorayya Malek, C. U. Emenike, P. Milow","doi":"10.3354/AB00701","DOIUrl":"https://doi.org/10.3354/AB00701","url":null,"abstract":"Ingestion of microplastics by marine organisms is a common occurrence in marine ecosystems, but the experimental demonstration of the effects of ingested microplastics on marine organisms has only recently become an important subject of research. In this review, the ingestion of microplastics by marine organisms, its attendant potential consequences and specific hypothetical questions for further studies are discussed. The formation of heteroaggregates in the gut of prey organisms may delay microplastic clearance, potentially increasing the chances of microplastic trophic transfer to predators. Also, the survival and energetics of keystone species at lower trophic levels are negatively affected by ingestion of microplastics, thereby raising questions about the transfer of energy and nutrients to organisms at higher trophic levels. Further, since microplastics are able to adsorb and concentrate organic pollutants up to 1 million times more than the pollutant concentration in ambient waters, the ingestion of such small plastic fragments is, a probable route for the entrance and biomagnification of toxic chemicals in the marine food web. However, the equilibrium state between pollutant concentration in marine organisms and that of surrounding waters makes it unclear whether the ingestion of microplastics actually increases the pollutant load of organisms. Finally, microplastic ingestion can cause endocrine disorders in adult fish, which could result in neoplasia via epigenetic programming. Therefore, microplastic pollution may be a contributory cause of increased incidents of neoplasia in marine animals. The amount of microplastics in marine waters will steadily rise, and questions about their impact on marine ecosystems will linger.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2018-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72995476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We studied the abundance of common zooplankton on 8 dates and at 5 locations on the shelf off the Lofoten Islands, northern Norway, between September 2013 and August 2014. We tested for relationships between environmental variability and abundances. We found that, of 17 zooplankton taxa or groups for which we recorded abundances, 4 omnivorous or carnivorous groups persistently differed in abundance between stations. This difference probably reflected relatively deep centres of distribution in the water column, and abundances of these species were positively associated with bottom depth. In 10 taxa or groups, abundance correlated with sampling date or temperature, salinity, or fluorescence, but generally not with bottom depth. Most of these taxa were consumers on low trophic levels, with a vertical distribution often associated with near-surface waters. In the remaining taxa or groups, no association between abundance and the environment or with time of sampling was established. Our results suggest that on-shelf abundances of zooplankton with intermediate-to-deep vertical distribution patterns are mainly limited by bathymetry, while abundance variations in zooplankton with a predominately near-surface distribution are driven by intra-annual environmental variability.
{"title":"Environmental effects on zooplankton abundance on a sub-Arctic shelf off northern Norway","authors":"K. Eiane, Marina Espinasse, B. Espinasse","doi":"10.3354/ab00697","DOIUrl":"https://doi.org/10.3354/ab00697","url":null,"abstract":"We studied the abundance of common zooplankton on 8 dates and at 5 locations on the shelf off the Lofoten Islands, northern Norway, between September 2013 and August 2014. We tested for relationships between environmental variability and abundances. We found that, of 17 zooplankton taxa or groups for which we recorded abundances, 4 omnivorous or carnivorous groups persistently differed in abundance between stations. This difference probably reflected relatively deep centres of distribution in the water column, and abundances of these species were positively associated with bottom depth. In 10 taxa or groups, abundance correlated with sampling date or temperature, salinity, or fluorescence, but generally not with bottom depth. Most of these taxa were consumers on low trophic levels, with a vertical distribution often associated with near-surface waters. In the remaining taxa or groups, no association between abundance and the environment or with time of sampling was established. Our results suggest that on-shelf abundances of zooplankton with intermediate-to-deep vertical distribution patterns are mainly limited by bathymetry, while abundance variations in zooplankton with a predominately near-surface distribution are driven by intra-annual environmental variability.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2018-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77249535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The evolution of asexual reproduction is considered a response to environmental conditions where it incurs less cost than sexual reproduction, maintains adapted genotypes and allows rapid proliferation into new areas. In rare circumstances, some species have evolved distinct asexual morphs or lineages in response to ubiquitous environmental conditions. Understanding the implications of, and the mechanisms underpinning, such reproductive strategies will be important for assessing the vulnerability of populations to environmental change. We examined morphological and genetic variation between 2 morphs of the kelp Ecklonia radiata, with sympatric haplodiplontic and vegetatively reproducing individuals growing side by side in Western Australia. Using 6 microsatellite markers, we show that vegetative morphs had a great propensity for asexual reproduction, with all attached haptera (8−20 per plant) being genetically identical to their parent plant. Moreover, for 8 multilocus genotypes (MLGs), Psex (probability that each MLG had clonal origins) scores were significant, suggesting clonal origins, and members of these MLGs were overwhelmingly dominated by individuals of the vegetative morph. Vegetative morphs were morphologically distinct, less morphologically variable, had lower genetic diversity and an excess of heterozygotes relative to haplodiplontic morphs. Nevertheless, vegetative morphs still produced and released zoospores at the same densities as haplodiplontic individuals, suggesting that they still complete an alternation of generations life history strategy. This likely accounted for weak genetic differentiation between morphs and suggests ongoing gene flow. Given that genetic diversity often confers adaptive capacity through change, low diversity may have implications for the vulnerability of this unique vegetative morph to local climatic and environmental stressors.
{"title":"Genetic and morphological diversity in sympatric kelps with contrasting reproductive strategies","authors":"M. Coleman, T. Wernberg","doi":"10.3354/AB00698","DOIUrl":"https://doi.org/10.3354/AB00698","url":null,"abstract":"The evolution of asexual reproduction is considered a response to environmental conditions where it incurs less cost than sexual reproduction, maintains adapted genotypes and allows rapid proliferation into new areas. In rare circumstances, some species have evolved distinct asexual morphs or lineages in response to ubiquitous environmental conditions. Understanding the implications of, and the mechanisms underpinning, such reproductive strategies will be important for assessing the vulnerability of populations to environmental change. We examined morphological and genetic variation between 2 morphs of the kelp Ecklonia radiata, with sympatric haplodiplontic and vegetatively reproducing individuals growing side by side in Western Australia. Using 6 microsatellite markers, we show that vegetative morphs had a great propensity for asexual reproduction, with all attached haptera (8−20 per plant) being genetically identical to their parent plant. Moreover, for 8 multilocus genotypes (MLGs), Psex (probability that each MLG had clonal origins) scores were significant, suggesting clonal origins, and members of these MLGs were overwhelmingly dominated by individuals of the vegetative morph. Vegetative morphs were morphologically distinct, less morphologically variable, had lower genetic diversity and an excess of heterozygotes relative to haplodiplontic morphs. Nevertheless, vegetative morphs still produced and released zoospores at the same densities as haplodiplontic individuals, suggesting that they still complete an alternation of generations life history strategy. This likely accounted for weak genetic differentiation between morphs and suggests ongoing gene flow. Given that genetic diversity often confers adaptive capacity through change, low diversity may have implications for the vulnerability of this unique vegetative morph to local climatic and environmental stressors.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2018-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87246738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Research on coral reproduction has increased dramatically in recent times; however, there remain significant regions, in particular high latitude reefs, where research is limited. For example, the reproductive biology of species in the coral assemblage at Hall Bank, a high latitude site (32 degrees S) in southern Western Australia, remain unknown. Here, reproductive traits and the likely time of spawning for 12 of the approximately 16 species that occur at Hall Bank were established using histology between March 2009 and March 2011 at 7 discrete time points. Peak reproductive activity most likely occurs in February, as 7 of the 10 species sampled in this month had colonies with mature gametes. The sexuality, mode of larval development and transmission of symbionts were, as expected, consistent with previous work. The reproductive biology of the corals at Hall Bank is consistent with other regions of the Indo-Pacific, supporting the hypo thesis that reproductive traits such as sexuality and mode of larval development are evolutionarily conserved and do not vary biogeographically.
{"title":"Coral reproduction at Hall Bank, a high latitude coral assemblage in Western Australia","authors":"A. Baird, D. Thomson","doi":"10.3354/AB00696","DOIUrl":"https://doi.org/10.3354/AB00696","url":null,"abstract":"Research on coral reproduction has increased dramatically in recent times; however, there remain significant regions, in particular high latitude reefs, where research is limited. For example, the reproductive biology of species in the coral assemblage at Hall Bank, a high latitude site (32 degrees S) in southern Western Australia, remain unknown. Here, reproductive traits and the likely time of spawning for 12 of the approximately 16 species that occur at Hall Bank were established using histology between March 2009 and March 2011 at 7 discrete time points. Peak reproductive activity most likely occurs in February, as 7 of the 10 species sampled in this month had colonies with mature gametes. The sexuality, mode of larval development and transmission of symbionts were, as expected, consistent with previous work. The reproductive biology of the corals at Hall Bank is consistent with other regions of the Indo-Pacific, supporting the hypo thesis that reproductive traits such as sexuality and mode of larval development are evolutionarily conserved and do not vary biogeographically.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2018-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91040579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Youenn Jézéquel, J. Bonnel, J. Coston-Guarini, J. Guarini, L. Chauvaud
Experiments in marine behavioural ecology rely heavily on observations made in tanks. However, when studying acoustic behaviours of marine animals in confined volumes, the effects of reverberation must be characterized, something that has been overlooked in parts of the marine ecology literature. In this study, we characterized reverberation in tanks using an artificial sound source and examined the implications for bioacoustic studies using sounds emitted by the European lobster Homarus gammarus during feeding and in response to stress. Broadband and transient sounds commonly produced by crustaceans were severely impacted by reverberation such that their spectral characteristics and pulse width durations could not be assessed. In contrast, low-frequency sounds could be characterized in tanks, but not their source level. Based on these observations, we describe a simple methodology to identify which sound characteristics can be measured in tanks. When feeding, the lobsters produced broadband and transient sounds called ‘rattles’, similar to sounds reported for tropical spiny lobsters Palinurus longipes and P. argus. When stressed, H. gammarus vibrated its carapace, producing a low-frequency sound analogous to the ‘buzzing’ sound of the American lobster H. americanus. The potential role of species-specific sound is discussed; however, although our observations represent the first bioacoustic characterization of H. gammarus, additional behavioural studies are necessary to understand their ecological meaning.
{"title":"Sound characterization of the European lobster Homarus gammarus in tanks","authors":"Youenn Jézéquel, J. Bonnel, J. Coston-Guarini, J. Guarini, L. Chauvaud","doi":"10.3354/AB00692","DOIUrl":"https://doi.org/10.3354/AB00692","url":null,"abstract":"Experiments in marine behavioural ecology rely heavily on observations made in tanks. However, when studying acoustic behaviours of marine animals in confined volumes, the effects of reverberation must be characterized, something that has been overlooked in parts of the marine ecology literature. In this study, we characterized reverberation in tanks using an artificial sound source and examined the implications for bioacoustic studies using sounds emitted by the European lobster Homarus gammarus during feeding and in response to stress. Broadband and transient sounds commonly produced by crustaceans were severely impacted by reverberation such that their spectral characteristics and pulse width durations could not be assessed. In contrast, low-frequency sounds could be characterized in tanks, but not their source level. Based on these observations, we describe a simple methodology to identify which sound characteristics can be measured in tanks. When feeding, the lobsters produced broadband and transient sounds called ‘rattles’, similar to sounds reported for tropical spiny lobsters Palinurus longipes and P. argus. When stressed, H. gammarus vibrated its carapace, producing a low-frequency sound analogous to the ‘buzzing’ sound of the American lobster H. americanus. The potential role of species-specific sound is discussed; however, although our observations represent the first bioacoustic characterization of H. gammarus, additional behavioural studies are necessary to understand their ecological meaning.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2018-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79182104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Pardo, M. P. Riveros, O. Chaparro, Katrin Pretterebner
In polygynous species, the sperm economy hypothesis predicts that males can adjust the amount of their ejaculate during copulation in response to (1) individual traits of females according to potential female fecundity, (2) future mating opportunities, and (3) risk of sperm competition. We tested this hypothesis in the crab Metacarcinus edwardsii by performing laboratory mating experiments to compare the response of males (sperm number and ejaculate weight delivered) in 3 sex-ratio scenarios: (1) equal, 1 female:1 male; (2) male-biased, 1 female:2 males; and (3) female-biased, 2 females:1 male. First, we determined if any variable, or an interaction between variables, could explain the variation in sperm or ejaculate amount delivered under an equal sex ratio. Second, we contrasted the ejaculate allocation among different sex-ratio scenarios. Under an equal sex ratio, males of M. edwardsii did not adjust their ejaculate allocation in response to any female trait. Male size was positively related to ejaculate delivery, indicating that the pair of vasa deferentia has ejaculate reserves that scale exponentially with male size. However, larger males delivered disproportionally more seminal fluid than sperm. Under a female-biased sex ratio, males did not show plasticity in their ejaculate allocation, but they increased their ejaculate investment (23%) per female under a male-biased sex ratio (i.e. risk of sperm competition). M. edwardsii presented a low level of ejaculate allocation, responding only when competitive males were perceived. In species with trans-molt sperm retention and long ejaculate storage, the risk of sperm competition is present all the time; therefore, males do not economize ejaculate even if more receptive females are available.
{"title":"Ejaculate allocation in Brachyura: What do males of Metacarcinus edwardsii respond to?","authors":"L. Pardo, M. P. Riveros, O. Chaparro, Katrin Pretterebner","doi":"10.3354/AB00693","DOIUrl":"https://doi.org/10.3354/AB00693","url":null,"abstract":"In polygynous species, the sperm economy hypothesis predicts that males can adjust the amount of their ejaculate during copulation in response to (1) individual traits of females according to potential female fecundity, (2) future mating opportunities, and (3) risk of sperm competition. We tested this hypothesis in the crab Metacarcinus edwardsii by performing laboratory mating experiments to compare the response of males (sperm number and ejaculate weight delivered) in 3 sex-ratio scenarios: (1) equal, 1 female:1 male; (2) male-biased, 1 female:2 males; and (3) female-biased, 2 females:1 male. First, we determined if any variable, or an interaction between variables, could explain the variation in sperm or ejaculate amount delivered under an equal sex ratio. Second, we contrasted the ejaculate allocation among different sex-ratio scenarios. Under an equal sex ratio, males of M. edwardsii did not adjust their ejaculate allocation in response to any female trait. Male size was positively related to ejaculate delivery, indicating that the pair of vasa deferentia has ejaculate reserves that scale exponentially with male size. However, larger males delivered disproportionally more seminal fluid than sperm. Under a female-biased sex ratio, males did not show plasticity in their ejaculate allocation, but they increased their ejaculate investment (23%) per female under a male-biased sex ratio (i.e. risk of sperm competition). M. edwardsii presented a low level of ejaculate allocation, responding only when competitive males were perceived. In species with trans-molt sperm retention and long ejaculate storage, the risk of sperm competition is present all the time; therefore, males do not economize ejaculate even if more receptive females are available.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2018-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82059967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Documenting the interactions and mechanisms of coexistence among predators is important for understanding their ecological roles in food webs. Here, we examined the diet and trophic relationships of 6 demersal batoids coexisting in the Gulf of Oman by analyzing stomach contents. There were significant differences in diets among the batoid species, suggesting differential preferences. Diets of Gymnura poecilura and Torpedo sinuspersici were similar and consisted mostly of teleost fishes. In contrast, Brevitrygon walga and Rhinobatos punctifer mostly ate crustaceans. The diets of Maculabatis randalli and Pastinachus sephen were diverse and included crustaceans, teleosts, polychaetes, bivalves and echinoderms. The differences in diet among these batoids may be related to morphological differences in feeding structures and to differences in behavior, which could explain their diversity and coexistence in the Gulf of Oman.
{"title":"Comparative diets of sympatric batoid elasmobranchs in the Gulf of Oman","authors":"A. Rastgoo, J. Navarro, T. Valinassab","doi":"10.3354/AB00694","DOIUrl":"https://doi.org/10.3354/AB00694","url":null,"abstract":"Documenting the interactions and mechanisms of coexistence among predators is important for understanding their ecological roles in food webs. Here, we examined the diet and trophic relationships of 6 demersal batoids coexisting in the Gulf of Oman by analyzing stomach contents. There were significant differences in diets among the batoid species, suggesting differential preferences. Diets of Gymnura poecilura and Torpedo sinuspersici were similar and consisted mostly of teleost fishes. In contrast, Brevitrygon walga and Rhinobatos punctifer mostly ate crustaceans. The diets of Maculabatis randalli and Pastinachus sephen were diverse and included crustaceans, teleosts, polychaetes, bivalves and echinoderms. The differences in diet among these batoids may be related to morphological differences in feeding structures and to differences in behavior, which could explain their diversity and coexistence in the Gulf of Oman.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2018-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85222625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many freshwater ecosystems suffer from multiple environmental stressors derived from anthropogenic activities. It is therefore necessary to investigate how environmental changes influence composition and functioning of biological communities such as zooplankton. At fine geographical scales, a well-known view on meta-community dynamics suggests that high dispersal can strongly homogenize community structure along water flows, largely erasing signals left by species sorting. However, a recent study by Xiong et al. (2017; Mol Ecol 26:4351−4360) challenges this view, showing that species sorting derived from an environmental gradient overrode the process of dispersal to determine the zooplankton community structure in running river ecosystems at fine geographical scales (the fine-scale species sorting hypothesis). Here we chose zooplankton communities from Fuyang River in north China to test the newly proposed hypothesis and identified the environmental factors contributing to meta-community dynamics in running water ecosystems. Multiple analyses based on high-throughput sequencing showed significantly varied zooplankton community composition and geographical distribution determined by an environmental gradient. Our study clearly shows that local chemical pollution, such as metal pollutants Cu and Mg, largely contributes to the observed patterns. Our study successfully identified local pollutants that influenced meta-community dynamics. Thus, we support the fine-scale species sorting hypothesis, indicating that a strong environmental gradient at fine geographical scales can strengthen the process of species sorting. As many rivers suffer from anthropogenic environ mental stressors, an urgent need exists to integrate both environmental and community infor mation when investigating how environmental changes influence community composition and functioning.
{"title":"Fine-scale environmental gradients formed by local pollutants largely impact zooplankton communities in running water ecosystems","authors":"Heng Peng, W. Xiong, A. Zhan","doi":"10.3354/AB00695","DOIUrl":"https://doi.org/10.3354/AB00695","url":null,"abstract":"Many freshwater ecosystems suffer from multiple environmental stressors derived from anthropogenic activities. It is therefore necessary to investigate how environmental changes influence composition and functioning of biological communities such as zooplankton. At fine geographical scales, a well-known view on meta-community dynamics suggests that high dispersal can strongly homogenize community structure along water flows, largely erasing signals left by species sorting. However, a recent study by Xiong et al. (2017; Mol Ecol 26:4351−4360) challenges this view, showing that species sorting derived from an environmental gradient overrode the process of dispersal to determine the zooplankton community structure in running river ecosystems at fine geographical scales (the fine-scale species sorting hypothesis). Here we chose zooplankton communities from Fuyang River in north China to test the newly proposed hypothesis and identified the environmental factors contributing to meta-community dynamics in running water ecosystems. Multiple analyses based on high-throughput sequencing showed significantly varied zooplankton community composition and geographical distribution determined by an environmental gradient. Our study clearly shows that local chemical pollution, such as metal pollutants Cu and Mg, largely contributes to the observed patterns. Our study successfully identified local pollutants that influenced meta-community dynamics. Thus, we support the fine-scale species sorting hypothesis, indicating that a strong environmental gradient at fine geographical scales can strengthen the process of species sorting. As many rivers suffer from anthropogenic environ mental stressors, an urgent need exists to integrate both environmental and community infor mation when investigating how environmental changes influence community composition and functioning.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2018-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81144711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kazutaka Takahashi, A. Kuwata, Takeo Suzuki, T. Toda, Keiichiro Ide
Diel changes in feeding habits and the relative contributions of daytime and nighttime diets to the nutrition of the mysid Orientomysis mitsukurii in a sandy shore environment were determined by field sampling and additional laboratory experiments. O. mitsukurii was distributed just above the bottom during the daytime but a subpopulation swam up into the water column at night. Nighttime swimming activity was prevalent in small individuals but progressively decreased at larger body sizes, while the gut pigment contents of all mysid size classes consistently increased at night. Stomach content analysis revealed that O. mitsukurii individuals of all size groups ingested sedimented particulate organic matter (POM) containing large quantities of clay minerals during the daytime, whereas they mainly foraged on planktonic diatoms in the water column at night. Estimated in situ algal ingestion rates at night accounted for approximately 80−95% of the daily carbon assimilation. O. mitsukurii also exhibited high efficiency in grazing on planktonic diatoms in laboratory experiments. Conversely, daytime sedimented POM carbon accounted for only a minor proportion (5−20%) of the daily carbon assimilation. The utilisation patterns of the different food sources were confirmed by carbon and nitrogen stable isotopic signatures in the benthic community. Our results suggest that efficient utilisation of primary producers, such as planktonic diatoms, by O. mitsukurii is beneficial for maintaining the species’ high abundance from an ecological transfer efficiency perspective, and that sedimented POM is an alternative food source for securing the basic energy required for their survival, particularly when phytoplankton availability is low.
{"title":"Diel changes of food sources and their contributions to nutrition of Orientomysis mitsukurii in a sandy shore environment","authors":"Kazutaka Takahashi, A. Kuwata, Takeo Suzuki, T. Toda, Keiichiro Ide","doi":"10.3354/AB00690","DOIUrl":"https://doi.org/10.3354/AB00690","url":null,"abstract":"Diel changes in feeding habits and the relative contributions of daytime and nighttime diets to the nutrition of the mysid Orientomysis mitsukurii in a sandy shore environment were determined by field sampling and additional laboratory experiments. O. mitsukurii was distributed just above the bottom during the daytime but a subpopulation swam up into the water column at night. Nighttime swimming activity was prevalent in small individuals but progressively decreased at larger body sizes, while the gut pigment contents of all mysid size classes consistently increased at night. Stomach content analysis revealed that O. mitsukurii individuals of all size groups ingested sedimented particulate organic matter (POM) containing large quantities of clay minerals during the daytime, whereas they mainly foraged on planktonic diatoms in the water column at night. Estimated in situ algal ingestion rates at night accounted for approximately 80−95% of the daily carbon assimilation. O. mitsukurii also exhibited high efficiency in grazing on planktonic diatoms in laboratory experiments. Conversely, daytime sedimented POM carbon accounted for only a minor proportion (5−20%) of the daily carbon assimilation. The utilisation patterns of the different food sources were confirmed by carbon and nitrogen stable isotopic signatures in the benthic community. Our results suggest that efficient utilisation of primary producers, such as planktonic diatoms, by O. mitsukurii is beneficial for maintaining the species’ high abundance from an ecological transfer efficiency perspective, and that sedimented POM is an alternative food source for securing the basic energy required for their survival, particularly when phytoplankton availability is low.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2017-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76499913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Acosta, Nelsy Niño-Rodríguez, María Camila Yepes, O. Boisseau
Population growth and economic development in Latin America has led to an increase in seismic surveying to find new marine hydrocarbon reserves. However, most countries along the Pacific, Atlantic, and Caribbean lack the standards to minimize the impact of seismic exploration on marine organisms. We searched primary and secondary literature in major databases and consulted international authorities and oil companies to provide scientific evidence of the effects of seismic surveying on fish and cetaceans in order to propose minimum guidelines to reduce disturbance to marine organisms in Latin America. The results suggest that seismic surveys can disrupt basic life-cycle activities such as movement, communication, and feeding. Typical outcomes include sub-lethal effects such as escape behavior, habituation, temporary loss of hearing, and changes in vocalization behavior. In order to mitigate these impacts, we propose that oil companies must provide authorities with an environmental impact assessment that includes survey data, array specifications, and acoustic array properties before a hydrocarbon exploration license can be granted. Standard mitigation measures such as exclusion zones, marine mammal observers, and passive acoustic monitoring must be implemented to prevent potential adverse effects. Appropriate legislation and regulations must be designed and implemented, and environmental authorities should be privy to all activities by seismic vessels. Besides relevant regulations and continued monitoring, further investigation must be conducted to evaluate the impact of these activities on marine organisms. The adoption of these proposed minimum guidelines is highly re commended to minimize seismic surveying impact on fish and cetaceans in Latin American countries.
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