昆承湖优势种鱼类时空-营养生态位

为了解昆承湖优势种鱼类资源利用情况,首先利用生态位方法计算了时间、空间及营养三个资源维度的生态位宽度及重叠值,然后根据时空-营养生态位宽度值将优势种鱼类划分为广位种、中位种和窄位种,最后讨论了生态位宽度及重叠的可能原因。结果显示：刀鲚Coilia nasus、蒙古鲌Chanodichthys mongolicus、似鱎Toxabramis swinhonis、似鳊Pseudobrama simoni、鳙Hypophthalmichthys nobilis、鲢Hypophthalmichthys molitrix、花鱼骨Hemibarbus maculatus、似刺鳊鮈Paracanthobrama guichenoti、大鳍鱊Acheilognathus macropterus和鲫Carassius auratus为优势种。在时间维度：鲢的生态位宽度最大,似鳊的最小;生态位重叠具有显著意义的有24对,占总的53.33%。在空间维度,似刺鳊鮈最大,鲢最小;生态位重叠具有显著意义的有36对,占总的80%。在营养维度,最大的为鲫,最小的为花鱼骨;生态位重叠具有显著意义的有8对,占17.78%...     

Trophic ecology and food consumption of fishes in a hypersaline tropical lagoon

This study evaluated the trophic ecology (diet composition, trophic strategy, similarities and overlap between species, feeding period and food consumption) of six benthivorous fish species in Araruama Lagoon, the largest hypersaline tropical lagoon on the east coast of South America, with an area of 210 km² and an average salinity of 52. The burrfish Chilomycterus spinosus fed on Anomalocardia flexuosa shell deposits, ingesting associated fauna. The caitipa mojarra Diapterus rhombeus differed from all other species, having not only the highest proportions of algae and Nematoda, but also feeding on polychaete tentacles. The two mojarras Eucinostomus spp. showed similar trophic strategies, feeding mostly on Polychaeta. The corocoro grunt Orthopristis ruber also fed mainly on Polychaeta, but differed from Eucinostomus spp. in secondary items. The whitemouth croacker Micropogonias furnieri fed mainly on small Crustacea at night, showing a high number of secondary prey items with low frequencies and high prey‐specific abundance. The daily food consumption (g food g^?1 fish mass) for Eucinostomus argenteus was 0·012 and was 0·031 and 0·027 for M. furnieri in two different sampling events. The diet similarities between Araruama Lagoon and other brackish and marine environments indicate that hypersalinity is not a predominant factor shaping the trophic ecology of fishes in this lagoon. The stability of hypersaline conditions, without a pronounced gradient, may explain the presence of several euryhaline fishes and invertebrates well adapted to this condition, resulting in a complex food web.     

Length–weight relationships for selected fish species from a coastal lagoon influenced by freshwater seeps: Yucatan peninsula,Mexico

The present work analyzes the relationship between length and weight for 28 fish species belonging to 16 families in Celestun lagoon, a natural marine reserve located in southeast Mexico that is influenced by freshwater seeps. With interrupted periods, a total of 14 846 specimens were collected from 1990 to 2006. The most abundant species were Eucinostomus argenteus, Eucinostomus gula, Anchoa mitchilli and Lagodon rhomboides. Exponents varied around b = 3.17 at P < 0.001, indicating a preference for isometric relationships. This study presents the first estimation of LWR for four species (Menidia colei, Lucania parva, Floridichthys polyommus, Garmanella pulchra) and the maximum length record for F. polyommus (19.5 cm standard length) that is greater than previously recorded.     

莱州湾鱼类群落优势种生态位

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)。δ~(13)C值变幅(CR)最大的种类为斑鱼祭(Konosirus punctatus),δ~(15)N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。     

Seasonal variation in diet and trophic relationships within the fish communities of the lower Slave River, Northwest Territories, Canada

Increased industrial activities on the Peace and Athabasca River systems have raised concerns about cumulative impacts on fish and water resources downstream, in the Slave River of Alberta and the Northwest Territories, Canada. Because very little information was available on the fish communities in this system, we examined spatial and temporal patterns of diet for nine species (four piscivores and five invertebrate feeders) from three different types of habitat along the lower Slave River system and assessed trophic relationships within the communities. All actively feeding species exhibited seasonal variations in diet within and among the study areas. Dietary overlap was generally low throughout all seasons and locations. In the lower Slave River and its major tributary, the Salt River, substantial dietary overlap between piscivores (particularly walleye, Stizostedion vitreum), and invertebrate feeders occurred in the spring. In the summer no overlap occurred as walleye shifted to a more piscivorous diet, attaining a moderate degree of overlap with northern pike, Esox lucius. Compared with the Slave River, which is a large but homogeneous system upstream of its delta at Great Slave Lake, there was a greater diversity of actively feeding invertebrate feeders in the Salt River. Three of the latter were benthic feeders exhibiting moderate degrees of diet overlap during spring and summer. During the fall, few fish were feeding. Most fishes in the lower Slave River system are generalist, opportunistic feeders, consuming a number of different prey, the importance of which varies spatially and seasonally, as the abundance of these prey varies in the environment.     

Seasonal variations of P compounds and their concentrations in two coastal lagoons (Herault,France)

This article concerns seasonal variations in the phosphate concentrations in two coastal lagoons near Montpellier (Mediterranean coast, France). The o-P concentration in the overlying water is highest during summer. The role of the sediment, particularly that of the different P fractions in the sediment, is discussed. Significant variations, especially in the FeOOH ≈ P fraction, occur. For both Tot-P_sed and the Fe00H≈P fraction a gradient from surface to bottom is observed, as well as a distinct decrease in the FeOOH≈P fraction in the surface sediments during summer and autumn. Variations in the FeOOH≈P fraction appear to be compensated by variations in the CaC0₃≈P fraction. These variations appear to be determined by the ferric hydroxide concentration. This compound represents only a small part (maximally 15%) of the total iron in the sediments and is related to the dissolved oxygen content of the immediately overlying water. Besides the fractions o-P, Fe(OOH)≈P, a large part of the CaC0₃≈P fraction is potentially bioavailable. A large proportion of the Tot-P_sed is therefore bioavailable.[/p]     

Structure and diversity of fishes in a freshwater and coastal subtropical lagoon

This study examined the fish communities of Peri Lagoon in southern Brazil to aid in the development of an effective management plan because the area is under threat from human activities. Sampling of fish fauna, ichthyoplankton and limnological data were compared between sites, differing by habitat type and characteristics such as depth, substratum composition and vegetation type. Results were significantly related to site, with the highest diversity and abundance recorded at shallow vegetated sites. A total of 14 fish species were recorded throughout the lagoon, with the most abundant being Hyphessobrycon luetkenii. Of the 14 species, half were sampled at their larval stage, suggesting a healthy and protected system. Significantly more larvae and eggs were collected during colder months (autumn to winter) and at sites closer to stream flow, possibly owing to increased food sources and habitat protection. This study highlights the importance of Peri Lagoon as a nursery ground for a wide range of fish species, providing essential information for incorporation into the future protection of fish stocks throughout Brazil.     

Biogeographical affinities,trophodynamics, and fisheries pressure in the fish community of the Laguna Madre Tamaulipas

The Laguna Madre Tamaulipas (LMT) is the largest hyperhaline coastal lagoon of Mexico, is diverse and provides a wide range of services, besides its economic importance for local and national fisheries. However, due to global and local pressures, the fish community is under stress. Here we study the LMT fish community to determine its biogeographical affinities with the Gulf of Mexico and Caribbean, understand its trophic relationships and habitat distribution, and to analyze the fisheries pressures in specific habitats and trophic groups (TGs). Our biogeographical analyses based on Parsimony Analysis of Endemism produce three provinces Center, South, and Northern, being this last the most related to the LMT, thus activities in this and the LMT directly affect each other. Through a nested cluster analysis using trophic values and size, 15 TGs were found, being the small‐species the most diverse and the largest the less diverse and most targeted by fishermen, which put on risk its ecological role and may provoke cascading effects on many species and processes. As well, mangroves and oyster banks habitats are supporting most of the fisheries. This is the first study of the whole fish community of the LMT, we pinpoint provinces, habitats, and TGs that need special attention and constant monitoring to generate integrative management plans that fit the actual needs of the community and prepare it to buffer future changes.     

Salinity and nutrients in a tropical coastal lagoon with groundwater discharges to the Gulf of Mexico

This study described the nutrient dynamics in a tropical coastal lagoon that is affected by the infiltration of cold nutrient-rich groundwater. The spatial and time variation of physicochemical characteristics (e.g., temperature, salinity, oxygen) and nutrients (e.g., nitrate, ammonium, soluble reactive silicate, soluble reactive phosphorus) are depicted and show changes with respect to weather conditions. The lagoon shows a permanent salinity gradient from the inner zone (14–19). Nitrate and soluble reactive silicate (SRSi) are inversely correlated with salinity. Soluble phosphorus (SRP) shows highest levels in the inner zone during winter months (>9 µM). Ammonium shows two high peaks, one in the rainy season (15 µM) and the other during winter (11 µM). The intensity and quality of rainfall influences the nitrate and SRSi inputs, while biological activity influences the SRP and ammonium levels.     

Composition, structure and distribution of the ichthyoplankton in a Mediterranean coastal lagoon

The species composition and assemblage structure of the ichthyoplankton from the Mar Menor Lagoon in south‐east Spain are given. The fish larvae were sorted from zooplankton samples collected at 20 stations with a plankton net (50 cm mouth diameter and 500 μm mesh) during 36 surveys between February and December 1997. A total of 39 575 fish larvae representing 14 families, 22 genera and 36 species were identified. Gobiidae was the most dominant family (77·0%) followed by Blenniidae (19·4%) and Atherinidae (1·3%). The most abundant species were Gobius niger and Gobius paganellus , which accounted for 42·7 and 19·3% of the total respectively. These species were followed in order of relative abundance by Pomatoschistus marmoratus (13·9%), Parablennius pilicornis (9·4%), Lipophrys pavo (7·7%), Atherina boyeri (1·3%) and Parablennius tentacularis (1·3%). The high species diversity (2·0–2·8 bits individual⁻¹ for the annual diversity spectra at each sampling station) reflected a diverse assemblage of species. The main commercial species in the lagoon (Sparidae and Mugilidae) were poorly represented among the ichthyoplankton and they probably enter the lagoon on the bottom as recruits. Chlorophyll a concentration in the water column was the main factor explaining the seasonal variation in larval abundance. Spatial distribution of larvae was related to hydrographical circulation patterns in the lagoon and the movement of marine‐spawned larvae through the channels connecting the lagoon with the Mediterranean Sea.     

Feeding patterns of the dominant benthic and demersal fish community in a temperate estuary

The diet and feeding relationships of the 12 most abundant benthic and demersal fish species of the Mondego Estuary, Portugal, were studied between June 2003 and May 2006. Fishes were caught during the night using a 2 m beam trawl. The stomach contents were analysed for prey identification, counting and weighing. According to prey importance in diets, three main feeding guilds were identified: (1) invertebrate feeders, (2) invertebrate and fish feeders and (3) plankton and invertebrate feeders. Besides these main feeding guilds, some fishes also presented fractions of algae and zooplankton in their stomach contents. The most abundant prey items were macroinvertebrates, with several polychaetes ( Nephtys spp., Capitellidae, Spionidae and Eunicidae), Corophium spp. and Crangon crangon among the dominant prey. Pomatoschistus spp. were the most preyed on fishes. Several fish species showed a tendency for a specialized diet, but almost all also showed some degree of opportunistic feeding by preying on other food resources. High diet overlap was found between some fish species, yet exploitative competition could not be concluded.     

Ultra- and microplankton assemblages as indicators of trophic status in a Mediterranean lagoon

The seasonal abundance distribution of heterotrophic prokaryotes, pico- and nanophytoplankton, was investigated in connection with environmental variables and microplankton abundance at five stations in Ghar El Melh Lagoon (northeastern Tunisia). Flow cytometry analysis of ultraplankton resolved (i) five heterotrophic prokaryote groups labelled LNA1, LNA2 (low nucleic acid content), HNA1, HNA2 and HNA3 (high nucleic acid content) and (ii) at least 14 ultraphytoplankton groups assigned to picoeukaryotes, picoprokaryotes, nanoeukaryotes, cryptophyte-like cells and some unknown communities. Redundancy analysis (RDA) revealed (i) autumn-summer outbreaks of heterotrophic prokaryotes dominated by HNA groups and (ii) winter-summer proliferation of ultraphytoplankton dominated by nanophytoplankton groups. Generalized additive models (GAM) highlighted the role of (i) water temperature and orthophosphate concentrations in heterotrophic prokaryote distribution and (ii) water temperature and salinity in ultraphytoplankton abundance variation. Based on Spearman's rank correlation, significant negative correlations were established between ultra- and microplankton communities suggesting that, through grazing pressure, microplankton may be behind the drastic decrease in ultraplankton abundances in spring.     

Lack of consistency between the trophic interrelationships of five sparid species in two adjacent central Mediterranean coastal lagoons

Both interspecific and intraspecific inter-lagoon differences, between the central Mediterranean coastal lakes of Fogliano and Caprolace, in the trophic patterns of the examined species Diplodus annularis, Diplodus puntazza, Diplodus sargus, Lithognathus mormyrus and Sparus aurata were revealed by means of correspondence analysis. The most evident inter-lagoon qualitative and quantitative diet changes were observed in S. aurata . Feeding similarities among species were synthesized for each lake by means of multidimensional scaling. Trophic interrelationships among sparid fish were different in the two lagoons, as a direct consequence of diet variations in each species. Such differences are interpreted as possibly reflecting differences in the overall structure of the benthic communities. Different feeding models could be identified, each corresponding to a peculiar adaptive strategy for the consumption of lagoon benthic resources. The use of benthophagous fish feeding habits as a tool for the monitoring of the structure and the dynamics of coastal lagoon communities is discussed.     

Seasonal depletion of resources intensifies trophic interactions in subarctic freshwater fish communities

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Feeding habits and seasonal trophic guilds structuring fish community in the bay mouth region of a tropical estuarine habitat

Understanding trophic relationships of fish in estuarine ecosystem is an important element for sustainable resource management. This study examined the feeding habits of 29 dominant fish species, characterized the trophic guilds, assessed the impact of season and clarified the role of diets in structuring the fish community in the mouth region of Pattani Bay, Thailand. Samples of 5792 fishes collected monthly by gillnets from March 2019 to February 2020 were used for stomach content analyses. It was found that the number of food types and fullness index differed between fish taxa (P < 0.001). Most fishes were specialist feeders feeding on specific food components and were categorized into five trophic guilds: piscivore, shrimp-fish feeder, polychaete feeder, zooplanktivore and planktivore. Six species were piscivorous, considered as apex predators, that fed almost entirely on fishes. High diet overlaps among some species (>0.6) were recorded. Not much variation in seasonal guilds was observed: four guilds in the dry season, three in the moderate rainy season and four in the rainy season. Some species remained in the same guild the whole year round, but some fishes changed seasonally. Two fish communities from different regions of the bay were segregated based on feeding habits. The inner bay community comprised mainly copepod and plankton feeders, but there were more piscivores in the deeper bay mouth area. Results from this study help us to understand the feeding habits and trophic guilds of dominant fish species at the mouth of this tropical estuarine bay.     

大宁河下游主要鱼类营养结构的时空变化

为了解大宁河下游主要鱼类食物网营养结构的时空变化特征,应用稳定同位素技术分析了大宁河下游巫山和大昌2个采样点在不同水位时期鱼类的碳、氮稳定同位素比值,并计算了δ13C-δ15N同位素生态位中的6个营养结构的量化指标。结果表明,不同水域的颗粒有机物(POM)的δ13C值随与河口距离而减小,δ15N值与河口距离无显著相关性。同种鱼类的δ13C值均无显著性差异;除了5月,巫山站点与大昌站点同种鱼类的δ15N值无显著性差异外,其他不同站点、不同水位时期同种鱼类的δ15N值均存在显著性差异。对同种鱼类组成的鱼类群落同位素量化指标比较发现,巫山站点10月鱼类群落的营养多样性指标及营养位置高于5月群落;大昌站点,不同水位时期的各指标变化趋势与巫山站相反。出现这种变化的原因可能是由于目前大宁河静水水域存在丰富的饵料导致。各鱼类群落营养结构的时空变化并未显示出处明显的规律性,可能与采样时间、鱼类种类的选择和样本量的大小有关。基于各种同位素值量化的生态指标应用于大宁河水域的鱼类食物网结构变化特征的研究,能为大宁河渔业生态调控措施以及渔业生态系统重建与修复提供理论依据。     

Seasonal and spatial variations of fish trophic guilds in a shallow,semi-enclosed tropical estuarine bay

A study on seasonal and spatial variations of feeding habits and trophic guilds of dominant fish species in Pattani Bay during March 2003 to February 2004 was aimed at classifying diet composition, identifying dominant food components of each species, categorizing trophic guilds of the community and evaluating effects of habitat characteristics and seasonality on guild organization. Most fishes showed high food intake, fed on a diverse range of food items but relied heavily on calanoid copepods and shrimps. All species, with the exception of Epinephelus coioides, were classified as specialist feeders. Four main dietary guilds were classified. Three of these were classified as the guilds dominated by at least two major food items. Significant variations in trophic guilds of 28 fish species based on habitat types and seasons were also identified. They could be divided into three seasonal groups and three site-groups and a single site. Trophic organization for each season and habitat ranged from two to four groups. This information identifies groups of fishes that seasonally and spatially utilize different food resources within a semi-enclosed estuarine bay ecosystem.     

The distribution of phosphate in sediments and its relation with eutrophication of a Mediterranean coastal lagoon

A major problem of the Mediterranean coastal lagoons is an excessive input of nutrients (i.e. N and P), causing eutrophic conditions in summer. The sediments of these lagoons can serve as a reservoir by fixing phosphate, or as a source when this phosphate is released under certain conditions. Knowledge of nutrient sources and fluxes is needed if coastal lagoons are to be protected against eutrophication. Therefore, we have evaluated the total pool of phosphate in the lagoon sediments, and the quantity of phosphate which may be released.Sediment profiles have been analysed at two stations of the Lagune de Thau both in and outside the oyster-bank zone. A sequential fractionation, using chelating agents was performed to extract the inorganic (iron and calcium bound phosphate) and the organic phosphate fractions. A statistical analysis of the data set has revealed several significant factors which explain the fluctuations of the concentrations of each phosphate fraction. These factors are: the time of year (seasons), the depth (5 cm layers of sediment), and the site (station).A spatial and a temporal variation of the concentration of Tot-P was found. The largest variation between the two different zones appeared only in the first five cm of sediment. There is only a slight seasonal variation in the amount of phosphate at other depths at the two different zones. Season and station are the factors which control the variations in distribution of phosphate fractions. The spatial and temporal variations of the iron and calcium bound phosphate are explained by the redox potential and pH in the top layer of the sediment.Abbreviations In principle the general abbreviations are used (see page vi). Futhermore Fe(OOH)-P= Ferric hydroxide bound phosphate - CaCO₃-P= Calcium carbonate bound phosphate - ASOP= Acid soluble organic phosphate - ROP= Residual organic phosphate     

Ecological effects of sex differ with trophic positions in a simple food web

Sexual differences in parental investment, predation pressure, and foraging efforts are common in nature and affect the trophic flow in food webs. Specifically, the sexual differences in predator and prey behavior change in trophic inflow and outflow, respectively, while those in parental investment alter the reproductive allocation of acquired resources in the population. Consequently, these factors may play an important role in determining the system structure and persistence. However, few studies have examined how sexual differences in trophic flow affect food web dynamics. In this study, I show the ecological role of sex by explicitly incorporating sexual differences in trophic flow into a three‐species food web model. The results demonstrated that the ecological waste of males, that is, the amount of trophic inflow into males with less parental investment, plays an important role in system persistence and structure. In particular, the synergy between sexual differences in parental investment and trophic inflows and outflows is important in determining web persistence: Significant impacts of male‐biased trophic flows require the condition of anisogamy. In addition, the dynamic effects of the ecological waste of males differ with trophic level: The coexistence of a food web occurs more frequently with biased inflows into predator males, but occurs less frequently with biased inflows into consumer males. The model analysis indicates that investigating the pattern of sexual differences among trophic positions can enrich our understanding of food web persistence and structure in the real world.