Nekton Community Structure Research Articles

Eco-Dynamic Analysis of the Community Structure of Nekton in the Northern South China Sea

The universal laws of thermodynamics in the process of ecosystem development have long been the common research focus of ecology and biophysics. Eco-exergy from thermodynamics is a popular theory in the study of ecosystem self-organization that has been widely used in the study of wetlands and aquatic ecosystems. This study is based on the data of bottom trawl fishery resources in the Northern South China Sea in 1964–1965, 1997–1999, 2006–2007, and 2017. Based on the eco-exergy theory, the exergy contribution rate (PC) of the nekton community and the exergy contribution rate (PL) of different organismic populations were constructed. The eco-exergy (EX) and specific eco-exergy (EXsp) of the nekton in the northeastern South China Sea were analyzed. The results show that, from 1964 to 2017, the EX and EXsp of the nekton community decreased 13.28-fold and 1.42-fold, respectively. Fish populations remained the major contributors to the EX and EXsp of the nekton community; however, compared to crustaceans and cephalopods, their role in maintaining the stability and complexity of the community structure was gradually weakened, and the genetic information per unit of biomass decreased. Meanwhile, compared to fish, the proportion of the EX of crustaceans and cephalopods in the nekton community showed an upward trend. The proportion of crustaceans increased from 2.76% in 1997–1999 to 14.84% in 2017, while that of cephalopods increased from 3.55% to 16.67%. Based on the findings, we speculate that crustaceans and cephalopods play an increasing role in the stability and complexity of the fishery resource structure in the Northern South China Sea. The species replacement in the nekton was obvious, and the dominant species of the Nekton community gradually changed from k-type species to r-type species in the Northern South China Sea.

Seines and baited remote underwater video document consistent spatiotemporal patterns in nekton communities of subtropical coastal habitats

Monitoring nekton using multiple types of gear over a range of estuarine habitats is necessary for assessing changes in ecosystems, the effects of natural and anthropogenic disturbances, and management related to habitat restoration and protection. To assess the utility of 2 types of gear (seines and baited remote underwater videos [BRUVs]) used in many monitoring programs, nekton community metrics were compared across 3 adjacent, hydrologically distinct coastal basins in Florida Bay (Florida, USA) across seasons (wet vs. dry) and 3 water-years (2016-2019). In these basins, projects are underway to restore freshwater inflow. Spatiotemporal patterns in catch per unit effort and species richness were consistent among types of gear, and nekton assemblages differed significantly among basins. Although similar in size and spatial area, the 3 study basins were notably different in habitat (hydrology, water depth, substrate, submerged aquatic vegetation), and 1 basin exhibited distinct basin-specific trends in nekton community structure and lower nekton abundance and species richness across types of gear. Temporal differences in nekton assemblages reflected seasonal shifts and were strongly affected by the passage of Hurricane Irma in 2017. Although seines and BRUVs revealed similar patterns, seine surveys captured more overall species diversity and prey species, while BRUVs could be used in a greater variety of habitats and documented more predators. These results demonstrate the effectiveness of complementary types of gear in tracking variation in estuarine communities and highlight the importance of a sampling design that successfully monitors species throughout the food web and estuarine seascape.

Plankton and nekton community structure in the vicinity of the South Sandwich Islands (Southern Ocean) and the influence of environmental factors

The South Sandwich Islands (SSI) are a biologically productive archipelago situated in the eastern Scotia Sea to the south of the eastward flowing Antarctic Circumpolar Current (ACC). The islands support important populations of higher predators, including several penguin species, seals and humpback whales. Despite this, the plankton ecology of the region has been little studied and information on mesoscale structure and environmental forcing of plankton ecology is particularly limited. We conducted a comprehensive oceanographic and net sampling campaign during the CCAMLR Area 48 Survey (January and February 2019), incorporating phytoplankton, mesozooplankton and macrozooplankton/nekton. Satellite chlorophyll-a (chl-a) data showed the development of a large bloom that was initiated two months prior to our study period at the south-eastern edge of the archipelago and propagated northwards along the eastern side, limited to the east by mesoscale features associated with the southern boundary of the ACC (SB). Multivariate cluster analysis revealed distinct mesoscale structure within the plankton community, with four spatially defined groups of phytoplankton and macrozooplankton/nekton, and three cluster groups of mesozooplankton. North of the SB, we found some spatial congruence between the three plankton assemblages, with a distinct, spatially coherent, cluster in each, corresponding to a warmer water community. Here, biomass was dominated by mesozooplankton, particularly calanoid copepods Rhincalanus gigas, Calanus propinquus, C. simillimus and Euchaetidae. The corresponding phytoplankton community was dominated by small diatoms, particularly Thalassionema spp., Pseudo-nitzschia spp., Fragilariopsis spp. and Chaetoceros spp., whilst Themisto gaudichaudii, Euphausia triacantha and myctophids were the major contributors to the macrozooplankton/nekton community. South of the SB, there was some spatial congruence between phytoplankton and macrozooplankton/nekton community structure on the western side of the archipelago, as well as on the eastern side that corresponded to the location of the bloom, but less association with mesozooplankton structure. Macrozooplankton/nekton structure was strongly driven by environmental conditions 1–2 months prior to the survey, including sea-ice distribution, surface phytoplankton concentration and productivity, whilst mesozooplankton was more tightly coupled to in-situ prevailing conditions such as surface temperature and integrated chl-a. Top-down pressure between trophic levels may have also had an influence on spatial patterns although direct evidence is lacking. Antarctic krill (Euphausia superba) was found with relatively low biomass at our net sampling sites (median biomass of 0.04 mg m−3 or <0.01 g m−2) while myctophids and the euphausiid Thysanoessa spp. predominated. We suggest that the highly productive and species rich pelagic community of the SSI supports multiple trophic pathways, and that off-shelf these may operate independently of Antarctic krill.

Spatial and temporal variabilities of coastal nekton community structure and phylogenetic diversity in Daya and Dapeng Bay, southern China

Coastal areas are important habitats for many species and strongly affected by anthropogenic activities. Management for sustainable coastal ecosystems benefits from a comprehensive assessment of species diversity. Here, we measured the spatio-temporal changes in community and phylogenetic structure of spring and autumn nektonic communities in Daya and Dapeng Bay among 12 sampling sites. We found that both the community structure and phylogenetic facets of nektonic communities in Daya and Dapeng Bay exhibited strong spatial and temporal patterns due which we attribute to fishing intensity and mid-summer fishing moratorium. The relatively larger ratio of unexplained variation in the autumn community resulted from stochastic processes caused by the mid-summer fishing moratorium. Furthermore, the phylogenetic structure of the spring nektonic communities between Dapeng and Daya Bay were significantly different; obvious phylogenetic clustering was found in spring nektonic communities of Dapeng Bay. These results implied that we may consider the current fishing intensity as a strong stress for nektonic communities, which exceeds the effect of natural processes and environmental factors. We speculate that the immediate sweeping fishing efforts may rapidly deplete the recovered fish stocks in a short time as human activities exert great stress on the nektonic communities in the study area. To avoid permanent damage to the ecosystem and a loss of valuable marine resources, urgent attention is required for fishery management.

Community structure of nekton in the waters around Dongtou Island in Autumn of 2019

Resource distribution characteristics of nekton in estuarine waters are related to hydrology, ecological environment changes and anthropogenic factors. A total of 49 species of nekton was found from 10 sites in the estuarine waters around Dongtou Island (DTI), with which the species of fish were in the highest proportion, followed by shrimp and crab. Average nekton biomass and abundance were 522.61 kg/km2 and 28.60×103 ind./km2, significantly higher than that of previous studies. The distribution pattern was highest in the eastern part of DTI, lower in the ORE area, and lowest in the northern part of DTI. The intersection of water currents was an important hydrological factor in forming the high resource density area of nekton. Changes in the number of nekton were driven by the contribution of the two economically valuable dominant species of fish Harpodon nehereus and crab Portunus trituberculatus. The mean value of H’ of nekton abundance was higher than that of nekton biomass. The species diversity of nekton in the sea near DTI was relatively low and community structure was in a relatively unstable state. The impact of human development activities on the nekton resources cannot be ignored, further research is essential.

Seascape Configuration Influences the Community Structure of Marsh Nekton

Around the globe, salt marsh ecosystems are rapidly changing, leading to alterations in both the amount, and configuration of marsh habitats. Sea level rise is a key driver of salt marsh change and is decreasing marsh habitat cover while increasing fragmentation. Such changes in seascape structure are expected to alter the ecological communities associated with marsh habitats. The influence of seascape structure on marsh nekton community structure is not well characterized, especially in coastal areas of the Gulf of Mexico, such as Louisiana (USA). Louisiana is losing marsh habitat at an unprecedented rate, and the resulting habitat loss and fragmentation provides a unique study system to investigate how marsh seascape structure impacts the nekton community. In this study, seascape structure was characterized at the 1- and 5-km scale at sampling points across several coastal basins to test marsh seascape structure effects on nekton community characteristics. Nekton communities were sampled using seine nets across coastal Louisiana in 2007. Total nekton community structure was found to be spatially driven. Both nekton species richness and nekton abundance were influenced by the shape of marsh patches and proportion of landscape marsh measured at either scale. While species richness differed only between some of the basins, each basin was found to have a statistically distinct community structure. Marsh shape influenced brown and white shrimp size. However, the response direction was found to be species specific, with brown shrimp size increasing in marshes with more complex shape while white shrimp size decreased. This study demonstrates that both environmental drivers and seascape structure play important roles in structuring marsh nekton communities, and that these responses can be species-specific. In order to project complex interactions between coastal land loss and their communities, a holistic framework of community structure, environmental drivers, and seascape characteristics is recommended.

Ecological consequences of shoreline armoring on littoral fish and benthic macroinvertebrate communities in an Eastern Ontario lake

Shoreline erosion in lakes is a pressing issue for many landowners, yet common erosion mitigation practices that involve armoring can alter littoral habitat and potentially diminish near-shore biodiversity. We studied the effects of two armoring methods (i.e., riprap, retaining walls) on habitat, taxonomic richness, relative abundance, and total abundance of fishes and benthic macroinvertebrates at shorelines on Big Rideau Lake in eastern Ontario, Canada. Snorkel surveys were conducted to assess aquatic habitat characteristics and fish diversity, and benthic infauna were sampled using kick-nets. Submergent and emergent macrophytes were more abundant at natural rocky shorelines compared to shorelines modified with riprap or retaining walls. Coarse woody debris was also more abundant at natural shorelines compared to riprap and retaining wall shorelines. Relative abundances of some fish species varied between shoreline types, but overall species richness and total abundance did not. Largemouth Bass (Micropterus salmoides) were more abundant at natural sites than armored sites. Conversely, Rock Bass (Ambloplites rupestris), Pumpkinseed (Lepomis gibbosus), Bluegill (Lepomis macrochirus), Yellow Perch (Perca flavescens), and baitfish from the family Cyprinidae were more abundant at both types of armored sites compared to natural sites. Taxonomic richness of benthic macroinvertebrates did not vary among shoreline types, however abundance of Amphipoda, Isopoda, Ephemeroptera, and Cladocera was greater at armored shorelines. These results suggest that human modification of shorelines is altering littoral ecosystems and potentially leading to shifts in the community structure of littoral nekton. More study is needed to fully understand the community level effects of shoreline erosion mitigation involving armoring in freshwater lakes and determine the effectiveness of alternative mitigation strategies that preserve natural habitat features.

Expected Shifts in Nekton Community Following Salinity Reduction: Insights into Restoration and Management of Transitional Water Habitats

A restoration project is planned to take place in the northern Venice lagoon (northern Adriatic Sea, Italy), aiming at introducing freshwater into a confined shallow water lagoon area and recreating transitional water habitats. This work describes the shifts in the nekton (fish and decapods) community structure to be expected following the future salinity decrease in the restoration area. Nekton was sampled at a series of natural shallow water sites located along salinity gradients in the Venice lagoon. A multivariate GLM approach was followed in order to predict species biomass under the salinity and environmental conditions expected after restoration. Biomass of commercially important species, as well as species of conservation interest, is predicted to increase following salinity reduction and habitat changes. From a functional perspective, an increase in biomass of hyperbenthivores-zooplanctivores, hyperbenthivores-piscivores and detritivores is also expected. This study emphasises the efficacy of a predictive approach for both ecological restoration and ecosystem management in transitional waters. By providing scenarios of community structure, the outcomes of this work could be employed in future evaluations of restoration success in the Venice lagoon, as well as to develop management tools to forecast the effects of alterations of salinity regimes in coastal lagoons due to climate change.

Effects of Nonnative Eurasian Watermilfoil, Myriophyllum spicatum, on Nekton Habitat Quality in a Louisiana Oligohaline Estuary

Submerged aquatic vegetation (SAV) provides critical habitat for estuarine nekton in the Gulf of Mexico, but habitat quality of SAV beds may change when nonnative species, such as Eurasian watermilfoil (Myriophyllum spicatum), become established. We compared the habitat value of Myriophyllum with another common native SAV (Ruppia maritima) by using field collections to document shifts in nekton community structure and a field experiment to compare growth rates of commercially important juvenile white shrimp (Litopenaeus setiferus). Similar communities were collected from both SAV species, though nekton abundance scaled with SAV biomass. The habitat quality provided by Myriophyllum for white shrimp appeared to meet or exceed that of Ruppia, with densities and growth rates of shrimp in Myriophyllum (2.2 ± 0.47 m−2, 1.0 ± 0.07 mm TL day−1, 25.7 ± 2.98 mg day−1) higher than in Ruppia (1.0 ± 0.36 m−2, 0.6 ± 0.09 mm TL day−1, 11.6 ± 2.04 mg day−1). Though differences were detected between SAV species, other factors, such as hypoxia and interspecific competition, likely contributed to the differences we documented between these habitat types in shrimp densities and growth. Our study provides an example of a nonnative habitat-forming species providing a viable alternative to native habitat. This result contradicts the paradigm of negative effects associated with nonnative species following their introduction into an ecosystem.

Community structure of nekton in the upstream of Wampu Watershed, North Sumatra, Indonesia

Desrita, Muhtadi A, Tamba IS, Ariyanti J, Sibagariang RD. 2018. Community structure of nekton in the upstream of Wampu Watershed, North Sumatra, Indonesia. Biodiversitas 19: 1366-1374. River is a habitat for many aquatic organisms. Water quality is the main river characteristic that strongly influences distribution pattern, biodiversity, and abundance of aquatic organisms. Nekton is aquatic organism that swims and moves actively on their desire, for example, fish, shrimp, amphibian and also big aquatic insects. The purpose of this research was to know the habitat condition and biodiversity of nekton in the upstream of Wampu watershed. The habitat condition was measured by examining the temperature, visibility, flow velocity, depth of waters, dissolved oxygen, pH, kind of substrate, the width of the river, body width of river and rate of flow of the river. The type of nekton was determined by catching the nekton using a backpack of electrofishing unit with an electric flow of 12 Volt and 9 Ampere. The upstream habitat condition of Wampu watershed was characterized by big stone, pebble, sandy type of substrate with moderate to strong current flow, and the clear aquatic. Physical and chemical parameters in upstream of Wampu watershed were still sustainable and appropriate as habitat for fish and shrimp. The result of this research showed a variety of nekton collected, comprised of 27 species of fish, five species of shrimp of inland water. Two species of fish from Tor genera, i.e., T. soro and T. tambroides were also found in this study. The highest diversity (H´) in this research site was the Bahorok River (2.12), followed by Landak River (1.93) at the second, and the lowest was Berkail River with only about 1.50 diversity index.

莱州湾鱼类群落优势种生态位

PDF HTML阅读 XML下载 导出引用 引用提醒 莱州湾鱼类群落优势种生态位 DOI: 10.5846/stxb201408281711 作者: 作者单位: 山东省海洋资源与环境研究院,山东省海洋资源与环境研究院,山东省海洋资源与环境研究院,烟台市水产研究所 作者简介: 通讯作者: 中图分类号: S931.1 基金项目: 山东省渔业资源增殖效果评价（SD-XGPJ-2012-2）；山东省优秀中青年科学家科研奖励基金（BS2012HZ030） Ecological niche of dominant species of fish assemblages in Laizhou Bay, China Author: Affiliation: Shandong Marine Resource and Environment Research Institute,Shandong Provincial Key Laboratory of Restoration for Marine Ecology,Shandong Marine Resource and Environment Research Institute,Shandong Provincial Key Laboratory of Restoration for Marine Ecology,Shandong Marine Resource and Environment Research Institute,Shandong Provincial Key Laboratory of Restoration for Marine Ecology,Yantai Fisheries Research Institute Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:根据2011年5月、8月、10月和12月莱州湾底拖网调查资料，对该海域鱼类群落优势种的生态位进行了研究。结果表明，全年调查共捕获鱼类49种，各季节优势种种类数分别为春季3种，夏季5种，秋季3种，冬季4种。夏、冬季优势种的丛生指数较低，春、秋季较高；冬、春季优势种的平均拥挤度较低，夏、秋季较高。基于欧氏距离的优势种丰度聚类结果同优势度排序结果吻合。主成分分析（PCA）表明，青鳞小沙丁鱼（Sardinella zunasi）和赤鼻棱鳀（Thryssa kammalensis）分别是影响第一轴和第二轴的主要种类。绯鱼衔（Callionymus beniteguri）、鲬（Platycephalus indicus）、髭缟虾虎鱼（Tridentiger barbatus）和短吻红舌鳎（Cynoglossus joyneri）是时空二维生态位宽度最高的种类（>2）。时空生态位显著重叠（>0.6）的种类有7组，其中银姑鱼（Pennahia argentata）和皮氏叫姑鱼（Johnius belengerii）重叠值最高（0.798）。δ13C值变幅（CR）最大的种类为斑鱼祭（Konosirus punctatus），δ15N值变幅（NR）最大的种类为青鳞小沙丁鱼；青鳞小沙丁鱼和鱼祭生态位总面积超过20，皮氏叫姑鱼生态位总面积最小（1.38）且与其他优势种营养生态位重叠较高。等级聚类、排序、PCA和优势种排序结果较一致，而与时空生态位宽度分析结果差异较大，表明莱州湾鱼类群落结构受洄游鱼类的影响较大。时空生态位宽度较高的种类主要为集群特征不明显的周年定居种（绯鱼衔、鲬、短吻红舌鳎等底层鱼类），而季节洄游种（青鳞小沙丁鱼、鱼祭、赤鼻棱鳀等中上层鱼类）因时间生态位宽度较低导致时空生态位宽度较低。时空生态位和营养生态位分析表明，生态位重叠导致的资源利用性竞争并不是导致莱州湾鱼类群落结构现状的决定性因素，而更多可能是人为干扰形成的。 Abstract:Laizhou Bay, an estuary of the Yellow River, is one of the three most important bays of the Bohai Sea, China. It is characterized by a high level of primary productivity and is one of the most important spawning and feeding grounds for most fish species in the Yellow Sea and Bohai Sea. After decades of overfishing, the dominant species of the fish assemblage have been altered. Ecological niche describes how an organism or population responds to the distribution of resources. Therefore, studies on ecological niches are extremely important to clarify the ecological dynamics of different species and the mechanism of interspecific coexistence and competition, as they are a fundamental tool for the conservation and assessment of fish stocks, as well as for the analysis of the ecosystem as a whole. Data were obtained from a bottom trawl survey conducted in Laizhou Bay (119°05'-120°00'E, 37°12'-37°40'N) in 2011. The most dominant species that contributed to 97.2% of biomass and 98.4% of abundance were used for the hierarchical cluster analysis, non-metric multidimensional scaling (NMDS), principal component analysis (PCA), and spatio-temporal niche analysis. Tissue samples were collected from the 12 most dominant species recorded in the trawl-survey catches. δ13C and δ15N stable-isotope analyses were performed to assess the trophic niche. A total of 49 fishes were collected. The assemblage density of dominant species was low in the summer and winter and high in the spring and autumn. The mean crowding of the dominant species was low in the spring and winter, and high in the summer and autumn. The results of the hierarchical cluster analysis based on the Euclidean distance showed a similarity with the results of the ecological dominance analysis. The PCA showed that Sardinella zunasi was one of the species that mostly affected the first axis, and Thryssa kammalensis mostly affected the second axis. Callionymus beniteguri had the highest value of tempo-spatial niche width, followed by Platycephalus indicus, Tridentiger barbatus, and Cynoglossus joyneri. Significant overlap of spatio-temporal niche occurred between the seven groups:Pennahia argentata vs. Setipinna taty (0.798), S. taty vs. Johnius belangerii (0.793), C. joyneri vs. J. belangerii (0.771), Chaeturichthys stigmatias vs. J. belangerii (0.770), Konosirus punctatus vs. Scomberomorus niphonius (0.763), and K. punctatus vs. C. joyneri (0.625). Konosirus punctatus had the highest δ13C range (CR=9.2), and J. belangerii had the highest δ15N range (NR=7.1). The total area (TA) of the trophic niche of S. zunasi and K. punctatus were the highest, both being larger than 20. Johnius belangerii had the lowest TA (1.38); however, it had a significant overlap with other species, such as C. stigmatias, C. joyneri, and P. argentata. The results showed a similar trend with cluster analysis, NMDS, and PCA; however, the trend was different with the tempo-spatial niche analysis. The non-migration species, which lives throughout year in the bay, with lower assemblage densities had a higher value of spatio-temporal niche width. The seasonal migratory species had a lower tempo-spatial niche width because of the low temporal niche width. The high spatio-temporal niche overlap between the most dominant species found in this study also reflected a high degree of homogeneity of fish assemblies in the Laizhou Bay. Competition owing to niche overlap was not the decisive factor that formed the community structure of nekton in the Laizhou Bay. The community structures might be most affected by anthropogenic activities. 参考文献 相似文献 引证文献

气候变化对冬季东海外海中下层游泳动物群落结构及重要经济种类的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 气候变化对冬季东海外海中下层游泳动物群落结构及重要经济种类的影响 DOI: 10.5846/stxb201512222549 作者: 作者单位: 中国水产科学研究院 东海水产研究所,中国水产科学研究院 东海水产研究所,中国水产科学研究院 东海水产研究所,日本水产综合研究中心 日本海区水产研究所,新泻 作者简介: 通讯作者: 中图分类号: 基金项目: 国家公益性行业（农业）科研专项（201303047） Impact of climate change on nekton community structure and some commercial species in the Offshore Area of the northern East China Sea in winter Author: Affiliation: Key Laboratory of East China Sea Oceanic Fishery Resources Exploitation and Utilization,Ministry of Agriculture,PRChinaEast China Sea fisheries Research Institute,Chinese Academy of Fishery Sciences;China,Key Laboratory of East China Sea Oceanic Fishery Resources Exploitation and Utilization,Ministry of Agriculture,PRChinaEast China Sea fisheries Research Institute,Chinese Academy of Fishery Sciences,Key Laboratory of East China Sea Oceanic Fishery Resources Exploitation and Utilization,Ministry of Agriculture,PRChinaEast China Sea fisheries Research Institute,Chinese Academy of Fishery Sciences,Japan Sea National Fisheries Research Institute,Fisheries Research Agency FRA,Suidou-cho,Chuo-ku,Niigata -,Japan Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以全球气候变暖为主要特征的全球气候变化对海洋生物和海洋生态系统造成的影响已引起国际学者的高度关注。根据中国14家国营渔业公司底拖网渔业生产和渔业资源大面定点调查获得的17种中下层渔业数据，结合1960-2011年东海北部水域海表温度的变化情况，利用Fox模型移除捕捞效应产生的趋势变化后，分析了气候变化对中、下层游泳动物群落结构及几种重要经济种类的影响。通过气候跃变检验分析发现，海表温度在整体变暖的趋势上叠加有年代际波动，研究水域分别在1982/1983年发生了从寒冷期（1960-1982年）向升温期（1983-1998）、经由1998/1999年再到温暖期（1999-2011年）的跃变。群落结构变化特征显示：相比于寒冷期，温暖期间底层类和大型捕食类资源指数降低，中层类和无脊椎类升高；暖水种资源指数升高，暖温种降低；生物多样性指数略有增加。移除捕捞效应后，对不同生态属性种类CPUE与海表温度距平进行相关分析显示：底层类、中层类和无脊椎类残差与海表温度距平均呈正相关关系，其中中层类与海表温度距平显著正相关，而大型捕食类则呈负相关关系；暖水种残差与海表温度距平呈正相关，而暖温种则呈负相关关系。中层类中的黄鲫（Setipinna taty）、银鲳（Pampus argenteus）的CPUE残差均与海表温度距平呈显著正相关关系，近底层类中的带鱼（Trichiurus japonicus）和头足类（Squid）的CPUE残差均与海表温度距平呈正相关关系，而底层类小黄鱼（Larimichthys polyactis）和对虾（Shrimp）则呈负相关关系。在气候变化的大背景下，需加强其对海洋生态系统结构和功能影响的研究，查明渔业资源对气候变化的响应机制和机理，制定科学有效的渔业管理制度，实现渔业资源的可持续发展。 Abstract:Recently, the influence of climate change on marine organisms and ecosystems has attracted attention on a global scale. In an effort to elucidate the impact of climate change on nekton community structure and on some commercial species in the northern East China Sea (NECS) during winter, we summarized the fluctuation of sea surface temperature (SST) in the offshore area of NECS from 1960-2011, and compared this to the catch data of 17 species targeted in bottom trawl fishery and to independent fishery data from the open waters of the NECS. We used Fox models to remove the effect of fishing pressure on changing population trends. Regime shift detection methods were used to identify change points in trends of production and environmental variables. Our results showed that the winter SST from 1960 to 2011 exhibited a long-term warming trend superimposed on interdecadal variability. The NECS experienced a cold period from 1960-1982, followed by a warming period from 1983 to 1998, and then a relatively stable warm period from 1999 to 2011. Changes in the community structure showed that the abundance of demersal and large predatory species was significantly negatively related to SST and the abundance of midwater species and invertebrates was positively related to SST. Abundance of large predatory species was lower in the warm period than in the cold period, while the abundance of midwater species and invertebrates was low in most of the years during 1971-1982, but increased during 1999-2011; catch of warm water species was higher in the warm period than in the cold period, but abundances were generally lower. At the same time, the Shannon diversity index was higher in the warm period than in the cold period. Upon removing the effect of fishing pressure, we found that catch per unit effort (CPUE) residuals for demersal species, midwater species and invertebrates had was positively correlated with SST, particularly the correlation between the CPUE residuals for midwater species and SST anomalies, which was significant. While CPUE residuals for large predatory species were negatively correlated with SST, CPUE residuals of warm water species/warm temperature species presented a positive/negative correlation with SST anomalies, respectively. Correlations between CPUE residuals and SST anomalies differed for commercial species based on habitat. Setipinna taty and Pampus argenteus were significantly and positively correlated with SST anomalies, while the correlation between Trichiurus japonicus, squid, and SST anomalies was positive. Larimichthys polyactis and shrimp were also positively correlated with SST anomalies. Considering the steadily warming climate, research priorities aimed at realizing the sustainable development of fishery resources should include analyzing the impact of warming temperatures on marine community structure and function, identifying variability in fishery resources in East China Sea and the mechanisms behind their responses, and developing scientific fishery management strategies. 参考文献 相似文献 引证文献

Status Limnologis Danau Siombak, Medan, Sumatra Utara

&lt;strong&gt;Limnological Status of Lake Siombak, Medan, North Sumatra.&lt;/strong&gt; Lake Siombak is located in the coastal area of Medan city, making its waters influenced by the tides. The lake serves as a water catchment, flood control, fishing area, and tourist destination. Various activities in the lake have led to changes in the environmental quality of the lake. To maintain the sustainability of the lake, efforts are needed for proper management. Lake management should begin with a good understanding of the nature and characteristics of the waters. This study aimed to determine the limnological status of Lake Siombak through morphometric analysis, aspects of physics, chemistry, and biology, as well as trophic status of the waters. Morphometry included dimensions of water surface and subsurface. Physics parameters included temperature, Total Suspended Solid (TSS), water clarity, electrical conductivity (EC), and salinity. Chemical parameters included pH, dissolved oxygen (DO), Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), nitrates, and phosphates. Biological parameters included community structure of nekton and benthos. Measurement of lake morphometry was performed in April 2014 at high and low tides. Measurements of water quality and biological sample collection were conducted in May-July 2014 at high and low tides. The results showed that Lake Siombak has an area of 41.44 ha with a maximum depth of 5 m at high tide and 4 m at low tide. Based on the aspects of physics, chemistry, and biology of the waters, Lake Siombak was categorized as an open waters influenced by the tides and was saline with high level of oxygen. The lake water retention time (Rt) was 15.65 hours and discharged (Q) 3.7 x 107 m3/h of water at high tide and 3.0 x 107 m3/h at low tide. High phosphate concentration indicated these waters have already been polluted. However, the water quality of Lake Siombak was still suitable for fishing activities. Benthos and nekton communities were relatively unstable. Benthic community was dominated by Blue Mussel (Mytilus edulis) at high tide (57%) and Red-rimmed Melania (Melanoides tuberculata) at low tide (41.34%). Nekton community was dominated by Blue Panchax (Aplocheilus panchax) at high tide (74.07%) and low tide (64.79%). In general, Lake Siombak was classified as eutrophic. &lt;br /&gt;&lt;br /&gt;

Demersal nekton community structure of artificial reef zones in Laoshan Bay, Qingdao

Demersal nekton community structure of artificial reef zones in Laoshan Bay, Qingdao

Spatial and temporal changes in assemblage structure of zooplankton and pelagic fish in the eastern Bering Sea across varying climate conditions

Zooplankton and pelagic fish samples collected on the eastern Bering Sea shelf in late summer 2003-2010 were used to evaluate spatial and temporal changes in the plankton and nekton community structure. The zooplankton were sampled by vertical towing of a Juday net (168 μm mesh) and oblique towing of a Bongo net (505 μm mesh), and pelagic fish were caught by midwater rope trawl. The communities were compared across climate regimes (in relatively warm and cold years), by latitude (in the northern and southern parts of the shelf), and by water depth (in the inner, middle, and outer domains of the shelf). Zooplankton were dominated by the small copepod Oithona spp. in warm years but relatively larger copepods Pseudocalanus spp. and Acartia spp. in cold years. Notably, the large copepod Calanus spp., an important energy-rich prey for fish, were more abundant in cold years than warm years. Age-0 walleye pollock Gadus chalcogrammus were more abundant in warm years, while capelin Mallotus villosus were abundant within cold-year communities over the northern shelf. Latitudinal variations in communities were more prominent in the cold years, particularly in 2007 and 2010. Cross-shelf variations were evident, particularly for large zooplankton and fish, with communities corresponding to specific oceanographic domains. Outer shelf communities varied less than inner and middle shelf communities between warm and cold periods, suggesting that this region may be less impacted by climate variability. An understanding of the overlap of zooplankton (prey) and fish communities within specific shelf regions or climate regimes may provide information for ecosystem-based approaches to fisheries management.

Species composition and stability of nekton community structure in Sandu Bay, Fujian Province

Species composition and stability of nekton community structure in Sandu Bay, Fujian Province

Loss of seasonal variability in nekton community structure in a tidal river: evidence for homogenization in a flow-altered system

Modifications to riverine systems that alter freshwater inflow to downstream estuarine habitats have resulted in altered patterns of nekton distribution and abundance. To examine how nekton assemblages respond to variable hydrologic patterns, we used trawl and seine survey data to compare the seasonal trends (dry vs. wet season) expected of a natural system to those of a river with regulated flow discharges that often magnify high flow events. Nekton assemblages differed between seasons in a representative natural system, similar to other estuaries of the region. For example, assemblage differences were characterized by significantly higher abundance and richness in trawl surveys, and significantly higher richness in seine surveys in the wet relative to the dry season. These seasonal trends were dampened in the altered system. Species important in defining seasonal dissimilarities in both systems were characterized as estuarine resident species, including Anchoa mitchilli, Menidia spp., Cynoscion arenarius, and Trinectes maculatus, yet were observed largely to have opposing seasonal trends in abundance between the two rivers. Our comparison provides evidence that flow modifications result in a loss of natural seasonal variability in estuarine nekton assemblages, but additional investigations of flow-altered systems are needed to confirm these findings.

Spatial Diversity in Composition and Structure of Nekton in Ngenep Spring and its Channels, Karangploso - Malang

Water springs and its channel degradation due to anthropogenic pollution may alter the community structure of aquatic organisms. Water spring degradation tehrefore affect the quality of water as tourism resources. This study aims to investigate the changes in community structure of nekton and determine the relationships between water quality characteristics to the diversity of nekton. The field survey was set up in Ngenep spring and its channels. Results showed that nekton species found in Ngenep spring and its channels consists of 4 classes, 4 orders, 6 families, and 7 species with total 627 nekton samples. It is comprises of fishes, shrimp, frogs and waterstriders. Nekton diversity index (H’) in the spring and irrigation channel were in moderate level (1&lt;H'&lt;3) while in settlement channel was low (0,67). Evenness values of nekton ranged 0,24 – 0,53, whereas dominancy index of nekton ranged 0,41 – 0,74. Evenness value in settlement channel was very low (0, 24) with high dominancy index (0, 74); it indicates that nekton species were spread not evenly in the channel, it dominated by fish Rasbora sp. (highest IVI, 184,95). There were spatial variations of physico-chemical water qualitiy parameters in Ngenep springs and its channels (temperature, stream velocity, turbidity, conductivity, pH, DO, BOD and TOM) which affected to nekton diversity and community structure. Clustering analyses and PCA result shows correlation pattern between nekton distribution with physico-chemical water quality parameters. However, physico-chemical water quality parameters in Ngenep springs and its channel were still optimum as nekton habitat (PP No. 82/ 2001). Keywords: Community structure , Nekton, Spatial diversity, Spring, Water channel

Nekton Community Structure Varies in Response to Coastal Urbanization Near Mangrove Tidal Tributaries

To assess the potential influence of coastal development on estuarine-habitat quality, we characterized land use and the intensity of land development surrounding small tidal tributaries in Tampa Bay. Based on this characterization, we classified tributaries as undeveloped, industrial, urban, or man-made (i.e., mosquito-control ditches). Over one third (37 %) of the tributaries have been heavily developed based on landscape development intensity (LDI) index values >5.0, while fewer than one third (28 %) remain relatively undeveloped (LDI < 3.0). We then examined the nekton community from 11 tributaries in watersheds representing the four defined land-use classes. Whereas mean nekton density was independent of land use, species richness and nekton-community structure were significantly different between urban and non-urban (i.e., undeveloped, industrial, man-made) tributaries. In urban creeks, the community was species-poor and dominated by high densities of poeciliid fishes, Poecilia latipinna and Gambusia holbrooki, while typically dominant estuarine taxa including Menidia spp., Fundulus grandis, and Adinia xenica were in low abundance and palaemonid grass shrimp were nearly absent. Densities of economically important taxa in urban creeks were only half that observed in five of the six undeveloped or industrial creeks, but were similar to those observed in mosquito ditches suggesting that habitat quality in urban and mosquito-ditch tributaries is suboptimal compared to undeveloped tidal creeks. Furthermore, five of nine common taxa were rarely collected in urban creeks. Our results suggest that urban development in coastal areas has the potential to alter the quality of habitat for nekton in small tidal tributaries as reflected by variation in the nekton community.

Linking Hydrogeomorphology and Food Webs in Intertidal Creeks

Intertidal creeks are shallow, photic ecosystems that potentially serve as sources of prey for many predators within estuaries. In a previous study, the link between nekton community structure and hydrogeomorphological variables for eight intertidal creeks was assessed for North Inlet estu- ary, South Carolina. Herein, we advance their findings through ecological network analysis of foodweb structure within two creeks and infer nekton trophic relationships to geomorphology and potential influences of hydrological condition and change. A summer network of a shallow, wide creek demonstrated greater carbon recycling, trophic effi- ciency and flow through consumers than that of a deep, narrow creek representing the same period. We infer greater export of nekton carbon from the former creek. These results were supported by analyses of nekton effective trophic levels and guilds across the eight creeks. Shallow, wide intertidal creeks appear to provide both physical and foodweb attri- butes that promote good nekton habitat relative to deeper and narrower creeks. Human alterations to flow regimes and sea- level rise have the ability to affect geomorphology of indi- vidual creeks and the landscape as a whole. These changes in turn have the potential to alter food webs of intertidal creeks and their ability to serve as sources of food for the larger estuary.