Detailed knowledge about basic metabolism in the early life stages of fishes helps increase our understanding of energetically important life phases. However, little is known about metabolic capacities during ontogenetic development of anemone fishes before and after settlement. This study established activities of 3 key metabolic enzymes — citrate synthase (CS), pyruvate kinase (PK) and lactate dehydrogenase (LDH) — to establish oxidative and glycolytic capacities in eggs, larvae and juveniles of false clownfish Amphiprion ocellaris before and after hatch, and during ontogenetic metamorphosis from the pelagic to sedentary mode of life (settlement stage). Oxidative capacity significantly increased after hatching and remained constant throughout development. Compared to just-hatched larvae (1−2 d old), the glycolytic and fermentative capacities on the contrary were about 2.5and 2.1-fold higher in pre-settlement (7−8 d old) larvae, respectively, and decreased significantly in post-settlement (15 d old) juveniles. Thus, relative gly co lytic enzyme activity ratios verified that settlement-stage anemone fish larvae mostly rely on glycolytic capacities for the burst-swimming capabilities needed during settlement before entering into the benthic mode of life. Intraspecific variances in enzyme activities due to ontogenetic transition should be considered when using key metabolic enzymes as biomarkers for analysing larval physiological status.
{"title":"Glycolytic capacities depend on developmental stage in the clownfish Amphiprion ocellaris","authors":"N. Paul, A. Kunzmann","doi":"10.3354/ab00721","DOIUrl":"https://doi.org/10.3354/ab00721","url":null,"abstract":"Detailed knowledge about basic metabolism in the early life stages of fishes helps increase our understanding of energetically important life phases. However, little is known about metabolic capacities during ontogenetic development of anemone fishes before and after settlement. This study established activities of 3 key metabolic enzymes — citrate synthase (CS), pyruvate kinase (PK) and lactate dehydrogenase (LDH) — to establish oxidative and glycolytic capacities in eggs, larvae and juveniles of false clownfish Amphiprion ocellaris before and after hatch, and during ontogenetic metamorphosis from the pelagic to sedentary mode of life (settlement stage). Oxidative capacity significantly increased after hatching and remained constant throughout development. Compared to just-hatched larvae (1−2 d old), the glycolytic and fermentative capacities on the contrary were about 2.5and 2.1-fold higher in pre-settlement (7−8 d old) larvae, respectively, and decreased significantly in post-settlement (15 d old) juveniles. Thus, relative gly co lytic enzyme activity ratios verified that settlement-stage anemone fish larvae mostly rely on glycolytic capacities for the burst-swimming capabilities needed during settlement before entering into the benthic mode of life. Intraspecific variances in enzyme activities due to ontogenetic transition should be considered when using key metabolic enzymes as biomarkers for analysing larval physiological status.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73195970","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}
Invasive aquatic plants have the potential to threaten ecosystem stability and bio diversity in non-native ranges; it is therefore necessary to prevent and control such invasions. While environmental heterogeneity might drive functional trait variation in plant species across different spatial scales, the drivers of trait variation over a large spatial scale are not well understood for aquatic invasive plants. Understanding functional trait variation across space and potential environmental drivers might improve our understanding of habitable conditions for predicting where an invasive plant species might be found. Here, we studied Hydrocotyle vulgaris (Araliaceae) in Zhejiang Province, China, and propose that environmental spatial heterogeneity might drive functional trait variation of this invasive aquatic plant over a large scale. The investigation was conducted across 99 plots at 7 sites with H. vulgaris. We found significant variation in functional traits over a large scale, and these functional traits were significantly different across a variety of environmental conditions. Specifically, there were significant relationships between environmental factors (i.e. temperature, precipitation, solar radiation, and water vapor pressure) and functional traits, including specific leaf area, interval length, and specific interval length, indicating that spatial environmental heterogeneity might drive the variation in functional traits (especially leaf and clonal traits) of H. vulgaris, over a large spatial scale. Our study thus provides new insights into understanding the invasiveness of H. vulgaris.
{"title":"Spatial environmental heterogeneity may drive functional trait variation in Hydrocotyle vulgaris (Araliaceae), an invasive aquatic plant","authors":"J. Wan, Mz Wang, Tj Qin, Xq Bu, Hl Li, Fh Yu","doi":"10.3354/ab00716","DOIUrl":"https://doi.org/10.3354/ab00716","url":null,"abstract":"Invasive aquatic plants have the potential to threaten ecosystem stability and bio diversity in non-native ranges; it is therefore necessary to prevent and control such invasions. While environmental heterogeneity might drive functional trait variation in plant species across different spatial scales, the drivers of trait variation over a large spatial scale are not well understood for aquatic invasive plants. Understanding functional trait variation across space and potential environmental drivers might improve our understanding of habitable conditions for predicting where an invasive plant species might be found. Here, we studied Hydrocotyle vulgaris (Araliaceae) in Zhejiang Province, China, and propose that environmental spatial heterogeneity might drive functional trait variation of this invasive aquatic plant over a large scale. The investigation was conducted across 99 plots at 7 sites with H. vulgaris. We found significant variation in functional traits over a large scale, and these functional traits were significantly different across a variety of environmental conditions. Specifically, there were significant relationships between environmental factors (i.e. temperature, precipitation, solar radiation, and water vapor pressure) and functional traits, including specific leaf area, interval length, and specific interval length, indicating that spatial environmental heterogeneity might drive the variation in functional traits (especially leaf and clonal traits) of H. vulgaris, over a large spatial scale. Our study thus provides new insights into understanding the invasiveness of H. vulgaris.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82403487","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 distribution range expansion of species mediated by natural or anthropic mechanisms is one of the main causes of changes in biodiversity patterns. Anemonia alicemartinae is a cryptogenic species found along the coasts of the Southeast Pacific Ocean. This species has ex panded its range by >1900 km along the Chilean coast throughout the last 50 yr. A. alicemartinae co habits with the native anemone Phymactis papillosa in the low intertidal zone, and given the limited mobility of both species, limited space could encourage aggressive behavior between them. P. papillosa shows different color phenotypes, and, as in other anemone species, color is associated with its level of aggressiveness. Here, we evaluated the aggressive behavior of A. alicemartinae on 2 color morphotypes of P. papillosa. Also, intraspecific agonistic interactions were considered in individuals of A. alicemartinae from 2 localities. Four experiments were conducted: (1) individual vs. individual, (2) individual vs. group forming a frontal line, (3) individual vs. group surrounding the individual and (4) group vs. group. Results showed A. alicemartinae to be a weak competitor against P. papillosa. The cryptogenic species lost more contests with green P. papillosa than with the red phenotype. Few aggressive interactions between conspecifics of A. alicemartinae were found. Results suggest that the expansion success of A. alicemartinae could be explained by alternative strategies, such as escape behavior, asexual reproduction and high dispersal potential.
{"title":"Aggressive interactions between the invasive anemone Anemonia alicemartinae and the native anemone Phymactis papillosa","authors":"A. Brante, R. Riera, P. Riquelme","doi":"10.3354/ab00718","DOIUrl":"https://doi.org/10.3354/ab00718","url":null,"abstract":"The distribution range expansion of species mediated by natural or anthropic mechanisms is one of the main causes of changes in biodiversity patterns. Anemonia alicemartinae is a cryptogenic species found along the coasts of the Southeast Pacific Ocean. This species has ex panded its range by >1900 km along the Chilean coast throughout the last 50 yr. A. alicemartinae co habits with the native anemone Phymactis papillosa in the low intertidal zone, and given the limited mobility of both species, limited space could encourage aggressive behavior between them. P. papillosa shows different color phenotypes, and, as in other anemone species, color is associated with its level of aggressiveness. Here, we evaluated the aggressive behavior of A. alicemartinae on 2 color morphotypes of P. papillosa. Also, intraspecific agonistic interactions were considered in individuals of A. alicemartinae from 2 localities. Four experiments were conducted: (1) individual vs. individual, (2) individual vs. group forming a frontal line, (3) individual vs. group surrounding the individual and (4) group vs. group. Results showed A. alicemartinae to be a weak competitor against P. papillosa. The cryptogenic species lost more contests with green P. papillosa than with the red phenotype. Few aggressive interactions between conspecifics of A. alicemartinae were found. Results suggest that the expansion success of A. alicemartinae could be explained by alternative strategies, such as escape behavior, asexual reproduction and high dispersal potential.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79143129","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}
Thermal stress can directly affect the survival of fishes and indirectly impact fish populations through several processes, including impaired swimming performance. Bigeye chub Hybopsis amblops is a state-endangered species in Illinois and is disappearing in the northern portion of its native range in North America. Limited temperature tolerance information exists on this species. The aim of this study was to define the impacts of 2 acclimation temperatures on the performance and behavior of bigeye chub. To accomplish this, we conducted 2 assays: critical thermal maximum (CTmax) testing for upper thermal tolerance limits, and swimming performance testing for critical swimming speed (Ucrit) and burst swimming ability. With a 5°C acclimation temperature increase from 21 to 26°C, the CTmax of bigeye chub increased from 32.8 ± 0.4°C to 36.4 ± 0.9°C. Ucrit was not different across acclimation temperatures, and fish from both acclimation groups could swim up to over 10 body lengths (BL) s−1. Burst swimming duration also did not differ statistically across groups, but bigeye chub from the 26°C group swam 27% longer in duration relative to fish from the 21°C group. Results from this study can help guide the protection and restoration of bigeye chub populations from thermal stressors.
{"title":"Effects of acclimation temperature on critical thermal limits and swimming performance of the state-endangered bigeye chub Hybopsis amblops","authors":"Qihong Dai, C. Suski","doi":"10.3354/ab00715","DOIUrl":"https://doi.org/10.3354/ab00715","url":null,"abstract":"Thermal stress can directly affect the survival of fishes and indirectly impact fish populations through several processes, including impaired swimming performance. Bigeye chub Hybopsis amblops is a state-endangered species in Illinois and is disappearing in the northern portion of its native range in North America. Limited temperature tolerance information exists on this species. The aim of this study was to define the impacts of 2 acclimation temperatures on the performance and behavior of bigeye chub. To accomplish this, we conducted 2 assays: critical thermal maximum (CTmax) testing for upper thermal tolerance limits, and swimming performance testing for critical swimming speed (Ucrit) and burst swimming ability. With a 5°C acclimation temperature increase from 21 to 26°C, the CTmax of bigeye chub increased from 32.8 ± 0.4°C to 36.4 ± 0.9°C. Ucrit was not different across acclimation temperatures, and fish from both acclimation groups could swim up to over 10 body lengths (BL) s−1. Burst swimming duration also did not differ statistically across groups, but bigeye chub from the 26°C group swam 27% longer in duration relative to fish from the 21°C group. Results from this study can help guide the protection and restoration of bigeye chub populations from thermal stressors.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88173501","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}
P. C. Simões‐Lopes, F. Daura-Jorge, L. Lodi, Carolina Bezamat, A. Costa, L. Wedekin
Phenotypic variations occur in several cetacean species, including common bottlenose dolphins Tursiops truncatus, which can also be distinguished as coastal and offshore ecotypes. In the western South Atlantic, these ecotypes have been described based on skeletal morphology and genetics. However, there is still no clear description to recognize them in the field. Here we searched for external diagnostic patterns that may facilitate their visual distinction and investigated their habitat use. We examined dorsal fin shapes and coloration of photo-identified dolphins distributed in a wide geographic range off the coast of southern and southeastern Brazil. A strong differentiation in the dorsal fin shape was observed, with a more falcate shape for offshore dolphins. We also found that offshore individuals have a darker color pattern, while coastal dolphins show 2 wider striped bands at the throat region and a longer rostrum, revealing that the ecotypes can be well distinguished in the field. We also detected differential habitat use. The coastal ecotype inhabits shallow waters (up to 18 m deep) close to the shore (up to 3 km). The offshore ecotype has a wider distribution and more flexible habitat use. It was usually found in coastal and deeper waters (maximum depth of 758 m and >200 km from the coast). Although we observed a small area of overlap in the distribution of the 2 ecotypes, both forms were not seen together. Therefore, our results reinforce the presence of a parapatric distribution and distinct morphology between the ecotypes, supporting their prior description as different subspecies.
{"title":"Bottlenose dolphin ecotypes of the western South Atlantic: the puzzle of habitats, coloration patterns and dorsal fin shapes","authors":"P. C. Simões‐Lopes, F. Daura-Jorge, L. Lodi, Carolina Bezamat, A. Costa, L. Wedekin","doi":"10.3354/AB00712","DOIUrl":"https://doi.org/10.3354/AB00712","url":null,"abstract":"Phenotypic variations occur in several cetacean species, including common bottlenose dolphins Tursiops truncatus, which can also be distinguished as coastal and offshore ecotypes. In the western South Atlantic, these ecotypes have been described based on skeletal morphology and genetics. However, there is still no clear description to recognize them in the field. Here we searched for external diagnostic patterns that may facilitate their visual distinction and investigated their habitat use. We examined dorsal fin shapes and coloration of photo-identified dolphins distributed in a wide geographic range off the coast of southern and southeastern Brazil. A strong differentiation in the dorsal fin shape was observed, with a more falcate shape for offshore dolphins. We also found that offshore individuals have a darker color pattern, while coastal dolphins show 2 wider striped bands at the throat region and a longer rostrum, revealing that the ecotypes can be well distinguished in the field. We also detected differential habitat use. The coastal ecotype inhabits shallow waters (up to 18 m deep) close to the shore (up to 3 km). The offshore ecotype has a wider distribution and more flexible habitat use. It was usually found in coastal and deeper waters (maximum depth of 758 m and >200 km from the coast). Although we observed a small area of overlap in the distribution of the 2 ecotypes, both forms were not seen together. Therefore, our results reinforce the presence of a parapatric distribution and distinct morphology between the ecotypes, supporting their prior description as different subspecies.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90568498","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}
Terrance Wang, Richelle L. Tanner, E. Armstrong, D. Lindberg, J. Stillman
Likelihood-ratio tests comparing the goodness-of-fit between the null model and alternative model were used to further evaluate the hypothesis that limpets of higher CTmax have reduced plasticy. Based on the assumption that limpet CTmax responds to local temperatures with plasticity, the null linear regression model included site and acclimation as the only two explanatory variables predicting CTmax. The alternative model included the interaction between acclimation and site as an additional explanatory variable. If the alternative hypothesis significantly fitted the observations better, coefficient estimates of the interaction between acclimation and site were compared to see how plasticity differed among sites. Null and alternative hypothesis models’ goodness-of-fit was also compared using AICc.
{"title":"Plasticity of foot muscle and cardiac thermal limits in the limpet Lottia limatula from locations with differing temperatures","authors":"Terrance Wang, Richelle L. Tanner, E. Armstrong, D. Lindberg, J. Stillman","doi":"10.3354/ab00714","DOIUrl":"https://doi.org/10.3354/ab00714","url":null,"abstract":"Likelihood-ratio tests comparing the goodness-of-fit between the null model and alternative model were used to further evaluate the hypothesis that limpets of higher CTmax have reduced plasticy. Based on the assumption that limpet CTmax responds to local temperatures with plasticity, the null linear regression model included site and acclimation as the only two explanatory variables predicting CTmax. The alternative model included the interaction between acclimation and site as an additional explanatory variable. If the alternative hypothesis significantly fitted the observations better, coefficient estimates of the interaction between acclimation and site were compared to see how plasticity differed among sites. Null and alternative hypothesis models’ goodness-of-fit was also compared using AICc.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89456132","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}
As the common carp Cyprinus carpio and African catfish Clarias gariepinus affect biotic assemblages in aquatic ecosystems through their benthivory, their introduction has been considered an environmental concern. We compare the effects of common carp and African catfish on adjacent trophic level assemblages of plankton, periphyton, benthic macroinvertebrates and native tilapia in a pond ecosystem at the National Aquaculture Center, Zomba, Malawi. Four treatments were involved in the study: ponds with common carp (T1), ponds with African catfish (T2), ponds with both common carp and African catfish (T3), and ponds lacking both common carp and African catfish (T4). In all treatments, the endemic Shire tilapia Oreochromis shiranus was also present as part of the local macrofauna. Results showed that T1 had the most abundant phytoplankton but the lowest periphyton, zooplankton and benthic macroinvertebrate abundance and diversity. T4 had the least phytoplankton but the most abundant and diverse zooplankton, periphyton and benthic macroinvertebrates. There was no significant difference between T2 and T3 (both intermediate to T1 and T4) in terms of phytoplankton, periphyton and benthic macroinvertebrate abundance and diversity. Better water quality regime and increased biomass of native tilapia fish were observed in T3 ponds. We conclude that the farming of common carp in aquatic ecosystems containing African catfish may not adversely affect the environment and that the polyculture of African catfish and common carp can be adopted as a management strategy to mitigate the potential adverse effects of common carp.
{"title":"Effects of common carp and African catfish on plankton, periphyton, benthic macroinvertebrates in pond ecosystem","authors":"E. R. Chirwa, A. Mtethiwa, W. Jere, D. Kassam","doi":"10.3354/AB00713","DOIUrl":"https://doi.org/10.3354/AB00713","url":null,"abstract":"As the common carp Cyprinus carpio and African catfish Clarias gariepinus affect biotic assemblages in aquatic ecosystems through their benthivory, their introduction has been considered an environmental concern. We compare the effects of common carp and African catfish on adjacent trophic level assemblages of plankton, periphyton, benthic macroinvertebrates and native tilapia in a pond ecosystem at the National Aquaculture Center, Zomba, Malawi. Four treatments were involved in the study: ponds with common carp (T1), ponds with African catfish (T2), ponds with both common carp and African catfish (T3), and ponds lacking both common carp and African catfish (T4). In all treatments, the endemic Shire tilapia Oreochromis shiranus was also present as part of the local macrofauna. Results showed that T1 had the most abundant phytoplankton but the lowest periphyton, zooplankton and benthic macroinvertebrate abundance and diversity. T4 had the least phytoplankton but the most abundant and diverse zooplankton, periphyton and benthic macroinvertebrates. There was no significant difference between T2 and T3 (both intermediate to T1 and T4) in terms of phytoplankton, periphyton and benthic macroinvertebrate abundance and diversity. Better water quality regime and increased biomass of native tilapia fish were observed in T3 ponds. We conclude that the farming of common carp in aquatic ecosystems containing African catfish may not adversely affect the environment and that the polyculture of African catfish and common carp can be adopted as a management strategy to mitigate the potential adverse effects of common carp.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80711557","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}
Andrias davidianus is one of most farmed amphibians owing to its palatability and nutritional value. In this transitional group between aquatic and terrestrial animals the effects of temperature and sex hormones on sex ratio and growth are not fully understood. Here, we quantified the sex dimorphism of A. davidianus growth with adult males approximately 30% larger than females, and for the first time determined the time of initiation of sex differentiation to be ~98 days post-hatching (dph). Mortality increased significantly with increased temperature, from 9.4% at 20°C to 40.6% at 28°C. At temperatures ≥30°C we observed 100% mortality. The proportion of males was 66.1% at 28°C, significantly higher than in the control group (p < 0.05). 17αestradiol induced larval feminization and produced female bias of 81−100% at concentrations from 25 μg l−1 to 1000 μg l−1. However, sex bias was not observed in larvae exposed to 17α-methyltestosterone at concentrations of 50 μg l−1 and 100 μg l−1. Additionally, growth characteristics at different temperatures showed that 28°C inhibited growth and 24°C promoted growth, reflecting the expression profile of growth-related genes (GH, GHR, and IGF-1). Sex steroids including 17βestradiol and 17α-methyltestosterone significantly inhibited growth (p < 0.05). The results suggest that water temperature and sex steroids play a vital role in gonad differentiation and growth of A. davidianus.
由于其适口性和营养价值，大鲵是养殖最多的两栖动物之一。在这个水生动物和陆生动物之间的过渡群体中，温度和性激素对性比例和生长的影响尚不完全清楚。本研究量化了大鲵的性别二态性，雄成虫比雌成虫大30%左右，并首次确定了雌雄分化的起始时间为孵化后98天。死亡率随温度升高而显著增加，从20℃时的9.4%增加到28℃时的40.6%。温度≥30°C时，死亡率为100%。28°C时，雄性比例为66.1%，显著高于对照组(p < 0.05)。在25 ~ 1000 μg l−1的浓度范围内，17α雌二醇诱导幼虫雌性化，雌性偏向率为81 ~ 100%。然而，暴露于浓度为50 μg l - 1和100 μg l - 1的17α-甲基睾酮的幼虫未观察到性别偏向。此外，不同温度下的生长特征显示，28℃抑制生长，24℃促进生长，这反映了生长相关基因(GH、GHR和IGF-1)的表达谱。性类固醇17β雌二醇和17α-甲基睾酮显著抑制生长(p < 0.05)。结果表明，水温和性激素对大鲵性腺的分化和生长起重要作用。
{"title":"Effects of temperature and sex steroids on sex ratio, growth, and growth-related gene expression in the Chinese giant salamander Andrias davidianus","authors":"Q. Hu, H. Tian, H. Xiao","doi":"10.3354/AB00710","DOIUrl":"https://doi.org/10.3354/AB00710","url":null,"abstract":"Andrias davidianus is one of most farmed amphibians owing to its palatability and nutritional value. In this transitional group between aquatic and terrestrial animals the effects of temperature and sex hormones on sex ratio and growth are not fully understood. Here, we quantified the sex dimorphism of A. davidianus growth with adult males approximately 30% larger than females, and for the first time determined the time of initiation of sex differentiation to be ~98 days post-hatching (dph). Mortality increased significantly with increased temperature, from 9.4% at 20°C to 40.6% at 28°C. At temperatures ≥30°C we observed 100% mortality. The proportion of males was 66.1% at 28°C, significantly higher than in the control group (p < 0.05). 17αestradiol induced larval feminization and produced female bias of 81−100% at concentrations from 25 μg l−1 to 1000 μg l−1. However, sex bias was not observed in larvae exposed to 17α-methyltestosterone at concentrations of 50 μg l−1 and 100 μg l−1. Additionally, growth characteristics at different temperatures showed that 28°C inhibited growth and 24°C promoted growth, reflecting the expression profile of growth-related genes (GH, GHR, and IGF-1). Sex steroids including 17βestradiol and 17α-methyltestosterone significantly inhibited growth (p < 0.05). The results suggest that water temperature and sex steroids play a vital role in gonad differentiation and growth of A. davidianus.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86161619","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}
Plastic pollution is present in aquatic systems worldwide. While numerous studies have investigated microplastic interactions with marine organisms, microplastic effects on freshwater organisms, especially insects, have been rarely studied. Previous studies have mainly focused on dietary uptake of microplastics, but the presence of microplastics in animal constructions is largely unknown. To date, microplastics have only been observed in the tubes of a marine polychaete species. In freshwater systems, common caddisfly (Trichoptera) larvae build cases by using larval silk and mineral grains from benthic sediments, which are known microplastic sinks. Therefore, we examined caddisfly cases for microplastic presence. We collected caddisfly Lepidostoma basale cases in the field, disintegrated them using hydrogen peroxide, and determined microplastic polymer type through micro-Fourier-transform infrared spectroscopy. We found primary and secondary microplastics of different shapes, colors, sizes and chemical compositions (e.g. poly propylene, polyethylene, polyvinyl chloride). Thus, this is the first study to show that microplastics are present in the biological construction of a freshwater organism. Larval stages are usually more vulnerable than adult individuals, and microplastics can transport persistent organic pollutants and emit toxic leachates. In the caddisfly larval case, those substances are in close proximity to the sensitive larval body, which may be harmful for the larva and may eventually impede its development. We discuss the potential of caddisfly larval cases to act as microplastic bioindicators in freshwater habitats.
{"title":"Microplastics of different characteristics are incorporated into the larval cases of the freshwater caddisfly Lepidostoma basale","authors":"Sonja M. Ehlers, W. Manz, J. Koop","doi":"10.3354/AB00711","DOIUrl":"https://doi.org/10.3354/AB00711","url":null,"abstract":"Plastic pollution is present in aquatic systems worldwide. While numerous studies have investigated microplastic interactions with marine organisms, microplastic effects on freshwater organisms, especially insects, have been rarely studied. Previous studies have mainly focused on dietary uptake of microplastics, but the presence of microplastics in animal constructions is largely unknown. To date, microplastics have only been observed in the tubes of a marine polychaete species. In freshwater systems, common caddisfly (Trichoptera) larvae build cases by using larval silk and mineral grains from benthic sediments, which are known microplastic sinks. Therefore, we examined caddisfly cases for microplastic presence. We collected caddisfly Lepidostoma basale cases in the field, disintegrated them using hydrogen peroxide, and determined microplastic polymer type through micro-Fourier-transform infrared spectroscopy. We found primary and secondary microplastics of different shapes, colors, sizes and chemical compositions (e.g. poly propylene, polyethylene, polyvinyl chloride). Thus, this is the first study to show that microplastics are present in the biological construction of a freshwater organism. Larval stages are usually more vulnerable than adult individuals, and microplastics can transport persistent organic pollutants and emit toxic leachates. In the caddisfly larval case, those substances are in close proximity to the sensitive larval body, which may be harmful for the larva and may eventually impede its development. We discuss the potential of caddisfly larval cases to act as microplastic bioindicators in freshwater habitats.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75167555","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}
Tanning is a complex extracellular process that is a mechanism for stabilizing proteinaceous extracellular structures. Phenoloxidases play important roles in cross-linking during tanning, and laccase (EC 1.10.3.2) is a member of the phenoloxidase enzyme class. In this study, we identified a laccase gene (MpLac) from the clam Meretrix petechialis and found that MpLac might be involved in shell periostracal tanning of clams. Using whole-mount in situ hybridization, we found that MpLac mRNA in the larval clam was mainly expressed in the mantle edge. In the adult clam, our quantitative real-time PCR results showed that the mantle was also a tissue with a high MpLac expression level; in addition, by combining the results of fluorescence in situ hybridization, H&E staining and transmission electron microscopy, we found that the inner epithelium of the outer fold of the mantle edge, which is involved in periostracum formation, was the exact region in which MpLac mRNA was expressed. Furthermore, knocking down the expression of MpLac by RNA interference (RNAi) bleached the new shell periostracum. All of our results suggest the involvement of MpLac in shell periostracal tanning of M. petechialis.
{"title":"Identification of a laccase gene involved in shell periostracal tanning of the clam Meretrix petechialis","authors":"Xin Yue, Zhang Shujing, Jiajia Yu, Liu Baozhong","doi":"10.3354/AB00709","DOIUrl":"https://doi.org/10.3354/AB00709","url":null,"abstract":"Tanning is a complex extracellular process that is a mechanism for stabilizing proteinaceous extracellular structures. Phenoloxidases play important roles in cross-linking during tanning, and laccase (EC 1.10.3.2) is a member of the phenoloxidase enzyme class. In this study, we identified a laccase gene (MpLac) from the clam Meretrix petechialis and found that MpLac might be involved in shell periostracal tanning of clams. Using whole-mount in situ hybridization, we found that MpLac mRNA in the larval clam was mainly expressed in the mantle edge. In the adult clam, our quantitative real-time PCR results showed that the mantle was also a tissue with a high MpLac expression level; in addition, by combining the results of fluorescence in situ hybridization, H&E staining and transmission electron microscopy, we found that the inner epithelium of the outer fold of the mantle edge, which is involved in periostracum formation, was the exact region in which MpLac mRNA was expressed. Furthermore, knocking down the expression of MpLac by RNA interference (RNAi) bleached the new shell periostracum. All of our results suggest the involvement of MpLac in shell periostracal tanning of M. petechialis.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75086173","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}
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