Cesar E. Tamaris-Turizo, A. G. APinilla, Cristian José Guzmán-Soto, CE Granados-Martínez
The importance of aquatic arthropods in the processing of organic matter in fluvial systems is well known, but this topic has been poorly studied in Neotropical rivers. In this research, we studied the composition of functional feeding groups (FFGs) associated with differences in elevation in a tropical river in northern Colombia during the wet and dry seasons. Between 2008 and 2013, we collected benthic arthropods at 3 sites located in the upper (San Lorenzo), intermediate (La Victoria) and lower (Puerto Mosquito) sections of the Gaira River. We found some differences in the gut contents and FFGs of the animals from different sites and between the climatic seasons. The dominant food source at all the sites and during both seasons was fine particulate organic matter (FPOM). At La Victoria, the genera Leptonema, Smicridea and Phylloicus (all belonging to Trichoptera) presented significant differences in the consumption of coarse particulate organic matter (CPOM) between the rainy and dry seasons (p < 0.05). At San Lorenzo, Leptonema had the highest animal tissue consumption value (p < 0.05). A discriminant function analysis based on gut contents suggested that some taxa may have been assigned to the wrong FFGs. We concluded that the diets of the aquatic arthropods in our study tended to present high trophic plasticity. Consequently, our results suggest that Neotropical rivers need to be reevaluated in terms of traditionally established FFGs, which heretofore have been based on in formation from other regions of the world, producing incorrect assessments of aquatic systems.
{"title":"Assigning functional feeding groups to aquatic arthropods in a Neotropical mountain river","authors":"Cesar E. Tamaris-Turizo, A. G. APinilla, Cristian José Guzmán-Soto, CE Granados-Martínez","doi":"10.3354/ab00724","DOIUrl":"https://doi.org/10.3354/ab00724","url":null,"abstract":"The importance of aquatic arthropods in the processing of organic matter in fluvial systems is well known, but this topic has been poorly studied in Neotropical rivers. In this research, we studied the composition of functional feeding groups (FFGs) associated with differences in elevation in a tropical river in northern Colombia during the wet and dry seasons. Between 2008 and 2013, we collected benthic arthropods at 3 sites located in the upper (San Lorenzo), intermediate (La Victoria) and lower (Puerto Mosquito) sections of the Gaira River. We found some differences in the gut contents and FFGs of the animals from different sites and between the climatic seasons. The dominant food source at all the sites and during both seasons was fine particulate organic matter (FPOM). At La Victoria, the genera Leptonema, Smicridea and Phylloicus (all belonging to Trichoptera) presented significant differences in the consumption of coarse particulate organic matter (CPOM) between the rainy and dry seasons (p < 0.05). At San Lorenzo, Leptonema had the highest animal tissue consumption value (p < 0.05). A discriminant function analysis based on gut contents suggested that some taxa may have been assigned to the wrong FFGs. We concluded that the diets of the aquatic arthropods in our study tended to present high trophic plasticity. Consequently, our results suggest that Neotropical rivers need to be reevaluated in terms of traditionally established FFGs, which heretofore have been based on in formation from other regions of the world, producing incorrect assessments of aquatic systems.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89747636","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}
F. Charles, P. Riera, P. Sauriau, F. Lantoine, B. Lebreton, H. Agogué, S. Hourdez
Marine wood-borers often live in sympatry, sharing deadwood scattered at sea, both as food and habitat. In this study, carbon and nitrogen isotope compositions were determined to test the hypothesis that the trophic niches of Chelura terebrans, Limnoria quadripunctata, and Nototeredo norvagica obtained from softwood boards maintained in running, unfiltered seawater are different. Comparison of isotope compositions supports niche partitioning, with N. norvagica foraging primarily on wood, and crustaceans foraging on decaying wood. Needs and acquisition routes for nitrogen determine the trophic behavior of the species. Results presented here are valuable for assessing the impact of wood-boring species on each other, but also for evaluating the effect of the separation of carbon and nitrogen sources on the diversity of the interactions between co-existing species belonging to the same trophic guild.
{"title":"Trophic niche partitioning in marine wood-borers revealed by stable isotope analysis","authors":"F. Charles, P. Riera, P. Sauriau, F. Lantoine, B. Lebreton, H. Agogué, S. Hourdez","doi":"10.3354/ab00723","DOIUrl":"https://doi.org/10.3354/ab00723","url":null,"abstract":"Marine wood-borers often live in sympatry, sharing deadwood scattered at sea, both as food and habitat. In this study, carbon and nitrogen isotope compositions were determined to test the hypothesis that the trophic niches of Chelura terebrans, Limnoria quadripunctata, and Nototeredo norvagica obtained from softwood boards maintained in running, unfiltered seawater are different. Comparison of isotope compositions supports niche partitioning, with N. norvagica foraging primarily on wood, and crustaceans foraging on decaying wood. Needs and acquisition routes for nitrogen determine the trophic behavior of the species. Results presented here are valuable for assessing the impact of wood-boring species on each other, but also for evaluating the effect of the separation of carbon and nitrogen sources on the diversity of the interactions between co-existing species belonging to the same trophic guild.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79001356","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}
Helena Kling Michelsen, E. M. Nilssen, T. Pedersen, C. Svensen
This study investigates the temporal and spatial patterns of larval stages of the invasive red king crab Paralithodes camtschaticus (RKC) and co-existing native brachyurans and anomurans in a Norwegian fjord. It is one of few field studies describing the larval stage of native and invasive brachyurans and anomurans in the southern Barents Sea. Larvae were collected at 6 to 18 stations at roughly 1 to 2 mo intervals over a 1.5-yr period. To help explain timing in hatch of RKC larvae, the reproductive state of females was determined. The first larval stage of RKC was found in higher abundances in shallow bays, reflecting the spawning migrations of reproducing females. RKC was the first species among anomurans and brachyurans to release their larvae in Norwegian waters, and due to an extended larval release (January−May) their larvae occurred for the longest period of time in the water column. The native boreo-Arctic Pagurus pubescens and Hyas araneus released their larvae early in the year, starting in March. In contrast, larvae of the native boreal Pagurus bernhardus, Hyas coarctatus and Munida sp. were observed later in spring and summer. The combination of protracted hatching, high fecundity and high adult abundance of RKC are likely strong contributing factors to the species’ successful establishment in the southern Barents Sea and could favour the dispersal of RKC south along the Norwegian coast and potentially north into Arctic shelf areas.
{"title":"Temporal and spatial dynamics of the invasive red king crab and native brachyuran and anomuran larvae in Norwegian waters","authors":"Helena Kling Michelsen, E. M. Nilssen, T. Pedersen, C. Svensen","doi":"10.3354/ab00720","DOIUrl":"https://doi.org/10.3354/ab00720","url":null,"abstract":"This study investigates the temporal and spatial patterns of larval stages of the invasive red king crab Paralithodes camtschaticus (RKC) and co-existing native brachyurans and anomurans in a Norwegian fjord. It is one of few field studies describing the larval stage of native and invasive brachyurans and anomurans in the southern Barents Sea. Larvae were collected at 6 to 18 stations at roughly 1 to 2 mo intervals over a 1.5-yr period. To help explain timing in hatch of RKC larvae, the reproductive state of females was determined. The first larval stage of RKC was found in higher abundances in shallow bays, reflecting the spawning migrations of reproducing females. RKC was the first species among anomurans and brachyurans to release their larvae in Norwegian waters, and due to an extended larval release (January−May) their larvae occurred for the longest period of time in the water column. The native boreo-Arctic Pagurus pubescens and Hyas araneus released their larvae early in the year, starting in March. In contrast, larvae of the native boreal Pagurus bernhardus, Hyas coarctatus and Munida sp. were observed later in spring and summer. The combination of protracted hatching, high fecundity and high adult abundance of RKC are likely strong contributing factors to the species’ successful establishment in the southern Barents Sea and could favour the dispersal of RKC south along the Norwegian coast and potentially north into Arctic shelf areas.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87870989","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}
Aging Antarctic icefish is difficult because of their lack of scales and poorly calcified bones. Icefish ages must therefore be estimated from otoliths. We describe a method of reading daily micro-increments in connection with shape, size and mass analyses of the otoliths of the South Georgia icefish Pseudochaenichthys georgianus. Changes in otolith morphology and mass correlate with fish size and age group. The otolith micro-increment analysis is capable of establishing the age of an icefish by relating the daily micro-increment count to the life history of the fish. Micro-increment measurements and analyses are relatively simple to do by light and scanning electron microscopy and by using micro-densitometer and digitizing equipment. Drastic changes in the life history of an individual are reflected by measurable changes in its otolith microincrement data as seen in our analyses of age groups 0−VI. The initial drastic change in daily micro-increment shapes and periodicities occur in connection with the hatching period of the icefish. The next drastic change in otolith shape and daily micro-increments occurs when ~7 cm long fish shift from pelagic to benthic habitats. As the fish age beyond group III, individual otolith variability lessens until they begin spawning. Our results indicate a single population of P. georgianus between the Antarctic Peninsula and South Georgia.
{"title":"Age determination in the icefish Pseudochaenichthys georgianus (Channichthyidae) based on multiple methods using otoliths","authors":"R. Traczyk, V. Meyer-Rochow, R. Hughes","doi":"10.3354/ab00736","DOIUrl":"https://doi.org/10.3354/ab00736","url":null,"abstract":"Aging Antarctic icefish is difficult because of their lack of scales and poorly calcified bones. Icefish ages must therefore be estimated from otoliths. We describe a method of reading daily micro-increments in connection with shape, size and mass analyses of the otoliths of the South Georgia icefish Pseudochaenichthys georgianus. Changes in otolith morphology and mass correlate with fish size and age group. The otolith micro-increment analysis is capable of establishing the age of an icefish by relating the daily micro-increment count to the life history of the fish. Micro-increment measurements and analyses are relatively simple to do by light and scanning electron microscopy and by using micro-densitometer and digitizing equipment. Drastic changes in the life history of an individual are reflected by measurable changes in its otolith microincrement data as seen in our analyses of age groups 0−VI. The initial drastic change in daily micro-increment shapes and periodicities occur in connection with the hatching period of the icefish. The next drastic change in otolith shape and daily micro-increments occurs when ~7 cm long fish shift from pelagic to benthic habitats. As the fish age beyond group III, individual otolith variability lessens until they begin spawning. Our results indicate a single population of P. georgianus between the Antarctic Peninsula and South Georgia.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81981888","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}
{"title":"Dietary preference of nile tilapia versus native fish species in the upper Kabompo River, northwest of Zambia","authors":"A. Jere, W. Jere, A. Mtethiwa, D. Kassam","doi":"10.3354/ab00738","DOIUrl":"https://doi.org/10.3354/ab00738","url":null,"abstract":"","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85524256","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}
Junichi Takagi, K. Ichikawa, N. Arai, J. Shoji, Hiromichi, Mitamura
Organisms live in groups on diverse spatial and temporal scales. Living in groups provides various advantages (Krause & Ruxton 2002, Sumpter 2010), such as increasing food search efficiency (Pitcher et al. 1982), reducing predation risk (Partridge 1982, Magurran 1990), and saving locomotion energy (Portugal et al. 2014, Hemelrijk et al. 2015, Marras et al. 2015). Navigational ability enhancement is also an advantage of group movement. For example, pigeons home more efficiently when travelling in flocks than when flying alone (Biro et al. 2006, Dell’Ariccia et al. 2008), and king penguin chicks return to their places of origin more efficiently when travelling in pairs than when moving alone (Nesterova et al. 2014).
生物在不同的时空尺度上群居生活。群体生活提供了各种优势(Krause & Ruxton 2002, Sumpter 2010)，例如提高食物搜索效率(Pitcher et al. 1982)，降低捕食风险(Partridge 1982, Magurran 1990)，节省运动能量(Portugal et al. 2014, Hemelrijk et al. 2015, Marras et al. 2015)。导航能力的增强也是群体运动的一个优势。例如，鸽子在成群旅行时比单独飞行时更有效地回家(Biro等人，2006年，Dell 'Ariccia等人，2008年)，王企鹅幼崽在成对旅行时比单独移动时更有效地返回它们的出生地(Nesterova等人，2014年)。
{"title":"Challenge of monitoring cohesive movement in homing fish using fine-scale 3D positioning","authors":"Junichi Takagi, K. Ichikawa, N. Arai, J. Shoji, Hiromichi, Mitamura","doi":"10.3354/ab00739","DOIUrl":"https://doi.org/10.3354/ab00739","url":null,"abstract":"Organisms live in groups on diverse spatial and temporal scales. Living in groups provides various advantages (Krause & Ruxton 2002, Sumpter 2010), such as increasing food search efficiency (Pitcher et al. 1982), reducing predation risk (Partridge 1982, Magurran 1990), and saving locomotion energy (Portugal et al. 2014, Hemelrijk et al. 2015, Marras et al. 2015). Navigational ability enhancement is also an advantage of group movement. For example, pigeons home more efficiently when travelling in flocks than when flying alone (Biro et al. 2006, Dell’Ariccia et al. 2008), and king penguin chicks return to their places of origin more efficiently when travelling in pairs than when moving alone (Nesterova et al. 2014).","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88160845","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 reproductive output of wild bottlenose dolphins Tursiops truncatus has extensively been investigated; nevertheless, it remains widely unexplored in the Mediterranean Sea. We investigated the reproductive history of female bottlenose dolphins in the Aeolian Archipelago (Italy). Thirteen years of photo-identification data were used to track the reproductive pattern of 7 females and their 16 calves. The birth period was accurately estimated within 1 mo for 6 calves (37.5%), peaking in June/July. The mean number of calves for females was 2.3 ± 1.1 (SD), ranging from 1 to 4. The mean interbirth interval was 3.5 ± 1.6 yr, ranging from 2 to 7 yr. The mean weaning age was 3.2 ± 0.6 yr, although 1 calf may have been weaned as late as its fifth birthday. Mother−calf postweaning associations were tracked for 9 calves and ranged from 4 to 10 yr of residence in the maternal group of the calf. The age of first pregnancy was 7.5 yr. The number of calves was influenced by the mean maternal group size, with females that were sighted in larger groups having more calves. However, the number of calves was not influenced by the strength of the associations of mothers with other females. Calf mortality by age 1 was high (12.5%). Two juveniles also died postweaning within 6 yr of their birth. Finally, 2 females may have died during the study, as they were not re-sighted at the end of the study. Our results highlight the need to implement urgent conservation actions to protect this bottlenose dolphin population.
{"title":"Female reproductive output in a Mediterranean bottlenose dolphin Tursiops truncatus population","authors":"M. Blasi, Chiara Bruno, L. Boitani","doi":"10.3354/ab00732","DOIUrl":"https://doi.org/10.3354/ab00732","url":null,"abstract":"The reproductive output of wild bottlenose dolphins Tursiops truncatus has extensively been investigated; nevertheless, it remains widely unexplored in the Mediterranean Sea. We investigated the reproductive history of female bottlenose dolphins in the Aeolian Archipelago (Italy). Thirteen years of photo-identification data were used to track the reproductive pattern of 7 females and their 16 calves. The birth period was accurately estimated within 1 mo for 6 calves (37.5%), peaking in June/July. The mean number of calves for females was 2.3 ± 1.1 (SD), ranging from 1 to 4. The mean interbirth interval was 3.5 ± 1.6 yr, ranging from 2 to 7 yr. The mean weaning age was 3.2 ± 0.6 yr, although 1 calf may have been weaned as late as its fifth birthday. Mother−calf postweaning associations were tracked for 9 calves and ranged from 4 to 10 yr of residence in the maternal group of the calf. The age of first pregnancy was 7.5 yr. The number of calves was influenced by the mean maternal group size, with females that were sighted in larger groups having more calves. However, the number of calves was not influenced by the strength of the associations of mothers with other females. Calf mortality by age 1 was high (12.5%). Two juveniles also died postweaning within 6 yr of their birth. Finally, 2 females may have died during the study, as they were not re-sighted at the end of the study. Our results highlight the need to implement urgent conservation actions to protect this bottlenose dolphin population.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84395519","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}
Freshwater fishes in the river and lake systems in the Himalayas and Tibetan Plateau are morphologically diverged but the evolutionary relationship of putative subspecies separated in these freshwater systems has not been explored. Snowtrout (Schizothorax spp.) are minnows (Cyprinidae) broadly distributed in Asia. Body shapes of 3 Lake Rara (northwest Nepal) endemics (S. macrophthalmus, S. nepalensis, S. raraensis) and 2 widely distributed riverine species (S. progastus, S. richardsonii) across 3 drainages in Nepal (i.e. Karnali, Gandaki, and Koshi Rivers) were studied using geometric morphometry. Data were derived from museum voucher specimens/ tissues collected in 1984−1986 and 1996 (Lake Rara). Cartesian coordinates of 18 anatomical points (Type I landmarks) from 528 individuals were digitized; shape variation was then quantified with principal component analysis and visualized with thin-plate splines derived from a Procrustes analysis. Models of shape variation (i.e. taxonomy versus geography) were tested with a multivariate analysis of variance and a morphological distance matrix. Phylogeographic relationships were examined with a haplotype network (N = 115) derived from 1140 base pairs of the mitochondrial DNA cyto chrome b gene, and selected GenBank sequences (N = 5). Koshi River snowtrout diverged morphologically from conspecifics, consistent with the phylogeographic data. In contrast, Gandaki and Karnali River snowtrout grouped by morphotype (upversus downstream) irrespective of geographic origin, yet clustered separately within the haplotype network. Lake Rara snowtrout were morphologically but not genetically distinct, due to incomplete lineage sorting. Morphological and genetic variability in Schizothorax from Nepal represent a mosaic driven by isolation (= vicariance) and specialization (= adaptation), with taxonomy insufficiently reflecting diversity. Additional data are required to appropriately derive management and effective conservation plans.
喜马拉雅和青藏高原的河流和湖泊系统中淡水鱼在形态上是分化的，但在这些淡水系统中分离的假定亚种的进化关系尚未探讨。雪鳟(Schizothorax spp.)是一种广泛分布于亚洲的小鱼(鲤科)。利用几何形态测量学研究了尼泊尔西北部拉拉湖3种特有物种(S. macrophthalmus, S. nepalensis, S. raraensis)和2种广泛分布的河流物种(S. progastus, S. richardsonii)在尼泊尔3个流域(即Karnali河、Gandaki河和Koshi河)的体型。数据来源于1984 - 1986年和1996年收集的博物馆代金券标本/组织(Lake Rara)。对528个个体的18个解剖点(I型地标)的笛卡尔坐标进行数字化处理;然后通过主成分分析对形状变化进行量化，并通过Procrustes分析得出薄板样条进行可视化。形状变化模型(即分类与地理)通过多元方差分析和形态距离矩阵进行检验。利用线粒体DNA细胞铬b基因1140个碱基对的单倍型网络(N = 115)和选定的GenBank序列(N = 5)来检验系统地理关系。Koshi河雪鳟在形态上与同种鱼不同，与系统地理数据一致。相比之下，Gandaki和Karnali河的雪鳟鱼不分地理来源，按形态类型分组(向上和下游)，但在单倍型网络中单独聚集。由于谱系分选不完全，拉拉湖的雪鳟鱼在形态上没有明显的遗传差异。尼泊尔Schizothorax的形态和遗传变异是由隔离(=变异)和专门化(=适应)驱动的马赛克，分类学不能充分反映多样性。需要更多的数据来适当地制定管理和有效的保护计划。
{"title":"Geometric morphometric analyses define riverine and lacustrine species flocks of Himalayan snowtrout (Cyprinidae: Schizothorax) in Nepal","authors":"Binod Regmi, Douglas, Edds, M. E. Douglas","doi":"10.3354/ab00737","DOIUrl":"https://doi.org/10.3354/ab00737","url":null,"abstract":"Freshwater fishes in the river and lake systems in the Himalayas and Tibetan Plateau are morphologically diverged but the evolutionary relationship of putative subspecies separated in these freshwater systems has not been explored. Snowtrout (Schizothorax spp.) are minnows (Cyprinidae) broadly distributed in Asia. Body shapes of 3 Lake Rara (northwest Nepal) endemics (S. macrophthalmus, S. nepalensis, S. raraensis) and 2 widely distributed riverine species (S. progastus, S. richardsonii) across 3 drainages in Nepal (i.e. Karnali, Gandaki, and Koshi Rivers) were studied using geometric morphometry. Data were derived from museum voucher specimens/ tissues collected in 1984−1986 and 1996 (Lake Rara). Cartesian coordinates of 18 anatomical points (Type I landmarks) from 528 individuals were digitized; shape variation was then quantified with principal component analysis and visualized with thin-plate splines derived from a Procrustes analysis. Models of shape variation (i.e. taxonomy versus geography) were tested with a multivariate analysis of variance and a morphological distance matrix. Phylogeographic relationships were examined with a haplotype network (N = 115) derived from 1140 base pairs of the mitochondrial DNA cyto chrome b gene, and selected GenBank sequences (N = 5). Koshi River snowtrout diverged morphologically from conspecifics, consistent with the phylogeographic data. In contrast, Gandaki and Karnali River snowtrout grouped by morphotype (upversus downstream) irrespective of geographic origin, yet clustered separately within the haplotype network. Lake Rara snowtrout were morphologically but not genetically distinct, due to incomplete lineage sorting. Morphological and genetic variability in Schizothorax from Nepal represent a mosaic driven by isolation (= vicariance) and specialization (= adaptation), with taxonomy insufficiently reflecting diversity. Additional data are required to appropriately derive management and effective conservation plans.","PeriodicalId":8111,"journal":{"name":"Aquatic Biology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86996152","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}
Spatial and temporal variability characterize submerged aquatic vegetation (SAV) assemblages, but understanding the complex interactions of environmental drivers of SAV assemblages remains elusive. We documented SAV composition and biomass across a salinity gradient in a coastal estuary over 12 mo. Ten macrophyte species were identified. The dominant species, Ceratophyllum demersum and Myriophyllum spicatum, accounted for over 40% of total biomass. Only Ruppia maritima occurred across the salinity gradient. Salinity, water depth and clarity delineated 3 assemblages: a saline assemblage, and 2 groups of fresher-water species, one associated with deeper water and lower water clarity and the other associated with shallow water and higher water clarity. These assemblages exhibited intra-annual variation, with at least 5 times more biomass in late spring/mid-summer compared to early winter. This pattern was consistent across the estuary, although the difference between peak and low biomass varied by habitat type; brackish exhibited the greatest magnitude. This variation is likely due to higher variation in salinity and the species composition of this habitat. As climate change and coastal restoration impact timing and range of salinity, water depth and clarity in this region, these data can be used to help inform predictive models and management decisions.
{"title":"Salinity and water clarity dictate seasonal variability in coastal submerged aquatic vegetation in subtropical estuarine environments","authors":"Eva R. Hillmann, Kristin DeMarco, M. L. Peyre","doi":"10.3354/ab00719","DOIUrl":"https://doi.org/10.3354/ab00719","url":null,"abstract":"Spatial and temporal variability characterize submerged aquatic vegetation (SAV) assemblages, but understanding the complex interactions of environmental drivers of SAV assemblages remains elusive. We documented SAV composition and biomass across a salinity gradient in a coastal estuary over 12 mo. Ten macrophyte species were identified. The dominant species, Ceratophyllum demersum and Myriophyllum spicatum, accounted for over 40% of total biomass. Only Ruppia maritima occurred across the salinity gradient. Salinity, water depth and clarity delineated 3 assemblages: a saline assemblage, and 2 groups of fresher-water species, one associated with deeper water and lower water clarity and the other associated with shallow water and higher water clarity. These assemblages exhibited intra-annual variation, with at least 5 times more biomass in late spring/mid-summer compared to early winter. This pattern was consistent across the estuary, although the difference between peak and low biomass varied by habitat type; brackish exhibited the greatest magnitude. This variation is likely due to higher variation in salinity and the species composition of this habitat. As climate change and coastal restoration impact timing and range of salinity, water depth and clarity in this region, these data can be used to help inform predictive models and management decisions.","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":"81034443","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}
Wild-living populations of the crucian carp Carassius carassius, a cyprinid fish of European freshwaters, have decreased in recent years, likely due to increasing competition presented by invasive species. Several initiatives have been launched in an attempt to reintroduce this fish back into its natural habitat, but these approaches require the use of crucian carp fry reared under controlled conditions, and the use of popular and inexpensive commercial diets has been found to result in developmental abnormalities. The aim of the current study was to analyse the impact of feeding juvenile crucian carp either natural food (Chironomidae sp. larvae) or 2 commercial diets, with a focus on the intestinal development of these fish. Histological analysis revealed significant pathologies in the alimentary tracts of fish fed both commercial diets; these included lowered hepatocyte and enterocyte proliferation, as well as shortened intestinal folds. Furthermore, the digestive enzyme activity patterns suggested a physiological state close to malnutrition. This study confirmed that basic commercial diets (at least the 2 applied) are not recommended for the rearing of crucian carp juveniles, even though initial growth rates of the fish might suggest otherwise.
{"title":"Effects of feeding commercial diets on the development of juvenile crucian carp Carassius carassius: digestive tract abnormalities","authors":"R. Kasprzak, T. Ostaszewska, M. Kamaszewski","doi":"10.3354/ab00717","DOIUrl":"https://doi.org/10.3354/ab00717","url":null,"abstract":"Wild-living populations of the crucian carp Carassius carassius, a cyprinid fish of European freshwaters, have decreased in recent years, likely due to increasing competition presented by invasive species. Several initiatives have been launched in an attempt to reintroduce this fish back into its natural habitat, but these approaches require the use of crucian carp fry reared under controlled conditions, and the use of popular and inexpensive commercial diets has been found to result in developmental abnormalities. The aim of the current study was to analyse the impact of feeding juvenile crucian carp either natural food (Chironomidae sp. larvae) or 2 commercial diets, with a focus on the intestinal development of these fish. Histological analysis revealed significant pathologies in the alimentary tracts of fish fed both commercial diets; these included lowered hepatocyte and enterocyte proliferation, as well as shortened intestinal folds. Furthermore, the digestive enzyme activity patterns suggested a physiological state close to malnutrition. This study confirmed that basic commercial diets (at least the 2 applied) are not recommended for the rearing of crucian carp juveniles, even though initial growth rates of the fish might suggest otherwise.","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":"80289524","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：