Patterns of fish species richness in China's lakes

Aim To document the patterns of fish species richness and their possible causes in China's lakes at regional and national scales. Location Lakes across China. Methods We compiled data of fish species richness, limnological characteristics and climatic variables for 109 lakes across five regions of China: East region, Northeast region, Southwest region, North‐Northwest region, and the Tibetan Plateau. Correlation analyses, regression models and a general linear model were used to explore the patterns of fish species richness. Results At the national scale, lake altitude, energy availability (potential evapotranspiration, PET) and lake area explained 79.6% of the total variation of the lake fish species richness. The determinants of the fish richness pattern varied among physiographic regions. Lake area was the strongest predictor of fish species richness in the East and Southwest lakes, accounting for 22.2% and 82.9% of the variation, respectively. Annual PET explained 68.7% of the variation of fish richness in the Northeast lakes. Maximum depth, mineralization degree, and lake area explained 45.5% of the fish variation in the lakes of the North‐Northwest region. On the Tibetan Plateau, lake altitude was the first predictor variable, interpreting 32.2% of the variation. Main conclusions Lake altitude was the most important factor explaining the variation of fish species richness across China's lakes, and accounted for 74.5% of the variation. This may stem in part from the fact that the lakes investigated in our study span the largest altitudinal range anywhere in the world. The effects of the lake altitude on fish species richness can be separated into direct and indirect aspects due to its collinearity with PET. We also found that the fish diversity and its determinants were scale‐dependent. Fish species richness was probably energy‐determined in the cold region, while it was best predicted by the lake area in the relatively geologically old region. The independent variables we used only explained a small fraction of the variations in the lake fish species richness in East China and the Tibetan Plateau, which may be due to the effects of human activity and historical events, respectively.     

Species richness of resident and transient coral-dwelling fish responds differentially to regional diversity

Aim To determine whether the diversity of resident and transient coral‐dwelling fish responds differentially to gradients in regional species richness. Location Three regions in the Indo‐Pacific (Red Sea, western Indian Ocean, Great Barrier Reef) which contain increasingly larger regional diversities of reef fish. Methods I surveyed fish residing within branching coral species. Fish species were a priori categorized as resident or transient based on the degree of affiliation between the fish and live coral. To compare among regions that differ in coral diversity I used a modified species–volume relationship (SVR). Each point in the SVR represents the total number of fish species, resident or transient, found within the cumulative volume of a specific coral species. Empirical SVRs were further compared with random‐placement null models. Results For transient species, I found that the observed SVRs did not differ consistently from those expected from random samples drawn from the corresponding regional species pools. In addition, for a given volume of coral, more fish species were found in richer regions, indicating strong regional influences on local diversity. In contrast, resident richness was lower than that expected from random samples of the species pool, and richness in rich regions was reduced comparably more than in poor regions. The SVRs of resident species were similar among regions with different regional diversities. Main conclusion These results suggest that, within coral species, transient fish richness is mostly influenced by stochastic allocation of species from the regional pool. Conversely, richness of resident species within a coral species is limited, making it independent of regional diversity. Since higher regional diversity of resident fish was not accompanied by higher richness per coral species or by decreased niche breadth, higher regional diversity of resident fish species must be rooted in higher coral richness. Consequently, ecological interactions between functional groups (coral and fish) can be powerful drivers of regional biodiversity.     

Microsatellite markers discriminate three species of North Atlantic wolffishes (Anarhichas spp.)

Sixteen tetranucleotide and dinucleotide microsatellite markers were isolated from Atlantic wolffish, Anarhichas lupus , following a microsatellite enrichment procedure using probe-labelled magnetic beads. These microsatellites were intended for use in Atlantic wolffish as well as in two closely related species, spotted wolffish, Anarhichas minor , and northern wolffish, Anarhichas denticulatus . As all three species are of conservation concern in Canadian waters and as forensic wildlife cases may arise for this genus, microsatellite markers were assessed to determine how well they differentiate these species from one another and to estimate probability values that could be expected for identification of individuals to species.     

Threatened fish species in the Northeast Atlantic are functionally rare

Aim

The criteria used to define the International Union for Conservation of Nature (IUCN) Red List categories are essentially based on demographic parameters at the species level, but they do not integrate species' traits or their roles in ecosystems. Consequently, current IUCN-based protection measures may not be sufficient to conserve ecosystem functioning and services. Some species may have a singular combination of traits associated with unique functions. Such functionally distinct species are increasingly recognized as a key facet of biodiversity since they are, by definition, functionally irreplaceable. The aim of this study is to investigate whether threatened species are also functionally rare and to identify which traits determine extinction risk.

Location

European continental shelf seas.

Time period

1984–2020.

Major taxa studied

Marine fish.

Methods

Using newly compiled trait information of 425 marine fish species in European waters, and more than 30 years of scientific bottom trawl surveys, we estimated the functional distinctiveness, restrictedness and scarcity of each species and cross-referenced it with their IUCN conservation status.

Results

In European continental shelf seas, 38% of the species threatened with extinction (9 out of 24 species) were identified as the most functionally distinct. By mapping extinction risk in the multidimensional species trait space, we showed that species with the greatest risk of extinction are long-lived and of high trophic level. We also identified that the most functionally distinct species are sparsely distributed (4% of the total area on average) and have scarce abundances (<1% of the relative mean abundance of common species).

Main Conclusions

Because a substantial proportion of threatened species are functionally distinct and thus may play unique roles in ecosystem functioning, we stress that species traits—especially functional rarity—should become an indispensable step in the development of conservation management plans.     

Long-term changes in temperate marine fish assemblages are driven by a small subset of species

The species composition of plant and animal assemblages across the globe has changed substantially over the past century. How do the dynamics of individual species cause this change? We classified species into seven unique categories of temporal dynamics based on the ordered sequence of presences and absences that each species contributes to an assemblage time series. We applied this framework to 14,434 species trajectories comprising 280 assemblages of temperate marine fishes surveyed annually for 20 or more years. Although 90% of the assemblages diverged in species composition from the baseline year, this compositional change was largely driven by only 8% of the species' trajectories. Quantifying the reorganization of assemblages based on species shared temporal dynamics should facilitate the task of monitoring and restoring biodiversity. We suggest ways in which our framework could provide informative measures of compositional change, as well as leverage future research on pattern and process in ecological systems.     

Trophic structure, species richness and biodiversity in Danish lakes: changes along a phosphorus gradient

1. Using data from 71, mainly shallow (an average mean depth of 3 m), Danish lakes with contrasting total phosphorus concentrations (summer mean 0.02–1.0 mg P L?l), we describe how species richness, biodiversity and trophic structure change along a total phosphorus (TP) gradient divided into five TP classes (class 1–5: <0.05, 0.05–0.1, 0.1–0.2, 0.2–0.4,> 0.4 mg P L?1).
2. With increasing TP, a significant decline was observed in the species richness of zooplankton and submerged macrophytes, while for fish, phytoplankton and floating‐leaved macrophytes, species richness was unimodally related to TP, all peaking at 0.1–0.4 mg P L?1. The Shannon–Wiener and the Hurlbert probability of inter‐specific encounter (PIE) diversity indices showed significant unimodal relationships to TP for zooplankton, phytoplankton and fish. Mean depth also contributed positively to the relationship for rotifers, phytoplankton and fish.
3. At low nutrient concentrations, piscivorous fish (particularly perch, Perca fluviatilis) were abundant and the biomass ratio of piscivores to plankti‐benthivorous cyprinids was high and the density of cyprinids low. Concurrently, the zooplankton was dominated by large‐bodied forms and the biomass ratio of zooplankton to phytoplankton and the calculated grazing pressure on phytoplankton were high. Phytoplankton biomass was low and submerged macrophyte abundance high.
4. With increasing TP, a major shift occurred in trophic structure. Catches of cyprinids in multiple mesh size gill nets increased 10‐fold from class 1 to class 5 and the weight ratio of piscivores to planktivores decreased from 0.6 in class 1 to 0.10–0.15 in classes 3–5. In addition, the mean body weight of dominant cyprinids (roach, Rutilus rutilus, and bream, Abramis brama) decreased two–threefold. Simultaneously, small cladocerans gradually became more important, and among copepods, a shift occurred from calanoid to cyclopoids. Mean body weight of cladocerans decreased from 5.1 μg in class 1 to 1.5 μg in class 5, and the biomass ratio of zooplankton to phytoplankton from 0.46 in class 1 to 0.08–0.15 in classes 3–5. Conversely, phytoplankton biomass and chlorophyll a increased 15‐fold from class 1 to 5 and submerged macrophytes disappeared from most lakes.
5. The suggestion that fish have a significant structuring role in eutrophic lakes is supported by data from three lakes in which major changes in the abundance of planktivorous fish occurred following fish kill or fish manipulation. In these lakes, studied for 8 years, a reduction in planktivores resulted in a major increase in cladoceran mean size and in the biomass ratio of zooplankton to phytoplankton, while chlorophyll a declined substantially. In comparison, no significant changes were observed in 33 ‘control’ lakes studied during the same period.     

乌江下游干流鱼类物种多样性及其资源保护

为摸清乌江下游干流现有的鱼类种类组成和物种多样性状况, 探索水电开发对鱼类群落多样性的影响, 本研究于银盘电站蓄水前的2006-2008年和蓄水后的2011-2013年, 采用渔获物调查方法对乌江下游沿河至白马干流江段鱼类进行了调查。两次调查共采集鱼类105种, 其中2006-2008年采集到100种, 2011-2013年采集到62种; 两次调查相比, 广适性鱼类减少10.38%, 湖沼定居型鱼类减少0.98%, 喜流水性鱼类减少9.62%。两个时期的鱼类群落多样性分析显示: 各个调查江段Margalef丰富度指数(R)和Shannon-Wiener多样性指数(H)在2011-2013年均低于2006-2008年。渔获物分析结果表明: 大鳍鳠(Mystus macropterus)、中华倒刺鲃(Spinibarbus sinensis)、瓣结鱼(Tor (Folifer) brevifilis)等鱼类在渔获物中的重量比例从2006-2008年间的大于5%, 下降到2011-2013年间的不足2%, 而(Hemiculter leucisculus)、草鱼(Ctenopharyngodon idellus)、黄颡鱼(Pelteobagrus fulvidraco)等在2011-2013年渔获物中的重量比例有所上升, 成为调查区域的主要渔获对象。丰度生物量比较表明: 2006-2008年鱼类群落结构受到中等程度的干扰, 而2011-2013年受到严重程度的干扰。为保护乌江下游的鱼类生物多样性, 需采取现有栖息地修复、控制过度捕捞等多种资源保护方式。     

Modelled spatial distribution of marine fish and projected modifications in the North Atlantic Ocean

The objectives of this work were to examine the past, current and potential influence of global climate change on the spatial distribution of some commercially exploited fish and to evaluate a recently proposed new ecological niche model (ENM) called nonparametric probabilistic ecological niche model (NPPEN). This new technique is based on a modified version of the test called Multiple Response Permutation Procedure (MRPP) using the generalized Mahalanobis distance. The technique was applied in the extratropical regions of the North Atlantic Ocean on eight commercially exploited fish species using three environmental parameters (sea surface temperature, bathymetry and sea surface salinity). The numerical procedure and the model allowed a better characterization of the niche (sensu Hutchinson) and an improved modelling of the spatial distribution of the species. Furthermore, the technique appeared to be robust to incomplete or bimodal training sets. Despite some potential limitations related to the choice of the climatic scenarios (A2 and B2), the type of physical model (ECHAM 4) and the absence of consideration of biotic interactions, modelled changes in species distribution explained some current observed shifts in dominance that occurred in the North Atlantic sector, and particularly in the North Sea. Although projected changes suggest a poleward movement of species, our results indicate that some species may not be able to track their climatic envelope and that climate change may have a prominent influence on fish distribution during this century. The phenomenon is likely to trigger locally major changes in the dominance of species with likely implications for socio‐economical systems. In this way, ENMs might provide a new management tool against which changes in the resource might be better anticipated.     

Invasion of North American drainages by alien fish species

1. Data from the literature were used to document colonization patterns by introduced freshwater fishes in 125 drainages across temperate North America. We analysed this data set to quantify susceptibility to invasion, success of the invaders and changes in species richness.
2. Drainages with a high number of impoundments, large basin area and low native species diversity had the greatest number of introduced species. Those drainages containing few native fishes exhibited great variation in the number of invaders, while waters with a rich native fauna contained few introduced species. However, this pattern did not differ significantly from random simulations because the pool of potential invaders is greater for drainages with low species richness.
3. In most drainages, there were more introduced than imperilled or extirpated species, suggesting that invaders tend to increase overall species richness.
4. These patterns suggest that North American fish communities are not saturated with species, but instead, are capable of supporting higher levels of diversity if the pool of potential colonists and the rate of colonization from that pool is increased.     

Genetic panmixia and demographic dependence across the North Atlantic in the deep-sea fish,blue hake (Antimora rostrata)

The efficient investment of resources and effort into conservation strategies depends on the accurate identification of management units. At the same time, understanding the processes by which population structure evolves requires an understanding of the conditions under which panmixia may exist. Here, we study a species with an unusual, apparently sex-biased pattern of distribution, and test the hypothesis that distribution processes associated with this pattern (for example, congregating at a single dominant spawning site or periodic mixing during reproduction) could lead to panmixia over a large geographic range. Using 13 microsatellite markers, we compared 393 blue hake (Antimora rostrata) from 11 sample sites across a geographic range of over 3000 km, and found no evidence of population structure. We estimated current effective population size and found it to be large (∼15 000) across the sampled area. In addition, we used simulation models to test expectations about demographic correlation among populations and our ability to detect relevant levels of gene flow. All data were consistent with the interpretation of long-range panmixia.     

Species diversity in native fish community in Japan: comparison between non-invaded and invaded ponds by exotic fish

The relationship between invasions by two exotic fishes (Micropterus salmoides and Lepomis macrochirus) and species diversity in native fish communities was studied in 14 Japanese farm ponds. We found that mean number of species in native fish communities was three times higher in the ponds without the exotic fish than in the ponds with them. Further, negative relationships were observed between abundance of the two exotic fish and the total abundance of native fish communities. Our results suggest that invasions by the two exotic fish caused serious depletion of native fish communities, although another process can also be considered , that is, that ponds with poor native fish communities were prone to colonization by these exotic fish.     

Biodiversity pattern of fish assemblages in Poyang Lake Basin: Threat and conservation

Poyang Lake Basin is of great importance to maintain regional ecological balance. However, fish biodiversity in this basin has rapidly declined as the result of anthropogenic habitat alteration, such as dam construction, sand mining, and water pollution. Here, we aimed to analyze the temporal and spatial changes in biodiversity patterns of fish in Poyang Lake Basin over the last 37 years. The number of fish species underwent a significant decrease in the current period. In particular, 36.7% of the migration of fish was extirpated. Twenty‐seven fish species have been formally assessed using the Chinese Red List were currently listed as Critically Endangered (9), Endangered (3), Vulnerable (10), and Near Threatened (5). Alpha and gamma diversity revealed that fish diversity had also decreased, and beta diversity showed significant composition dissimilarity in two periods. PCoA showed that the historical fish composition dissimilarity was significantly different from that of the current period. We found a significant effect of the geographical distance on the spatial turnover component for the historical and current periods. In addition, the nestedness component was the main contributor to beta diversity, which indicated one large protected area should be established in Poyang Lake and the Ganjiang River Basin with higher species richness. These results indicated that fish biodiversity declined in the current period likely caused by anthropogenic habitat alteration and other threatened factors. Therefore, we suggest that the habitat reconstruction and biodiversity conservation for fish have become imperative in this basin, and a complete management plan should be carried out.     

Species richness patterns of amphibians in southwestern Ontario ponds

Abstract. In southwestern Ontario amphibian species richness (α-diversity) was investigated at 180 ponds from 1992 to 1994. Patterns of species richness were compared among regions and the relationship between species richness and local habitat and regional landscape variables was investigated. Patterns of incidence differed among regions, with species that use woodlands being rare in one of the regions. Repeated measures analysis of variance indicated that species richness differed significantly among regions but not among sub-regions nested within regions. Species richness did not change significantly over time and there was no region by year effect. Species richness was highly correlated with local variables related to fish predation and to regional variables related to forest cover. Multiple regression indicated that a combination of local and regional variables best accounted for the variance in species richness, but the amount of regional woodlands was the single most important variable. The pattern of species richness can be explained by historical deforestation as the primary process.     

Historical influences dominate the population genetic structure of a sedentary marine fish,Atlantic wolffish (Anarhichas lupus), across the North Atlantic Ocean

Genetic variation was assessed in Atlantic wolffish, Anarhichas lupus, across the North Atlantic Ocean using microsatellite and amplified fragment length polymorphism (AFLP) markers. Despite unusual life history attributes such as large benthic eggs, large larvae, a limited pelagic stage and relatively sedentary adults, which suggest potential for strong population structure, range‐wide F_ST values were comparable to other marine fishes (≤0.035). Nevertheless, both significant genetic differentiation among regions and isolation by distance were observed, suggesting limited dispersal in this species. AFLP loci, evaluated on a subset of samples, revealed slightly higher F_ST values, but similar patterns of differentiation and isolation‐by‐distance estimates, compared to microsatellites. The genetic structure of Atlantic wolffish has likely been shaped by its post‐glacial history of recolonization, North Atlantic current patterns and continuity of habitat on continental shelves.     

太湖鱼类群落结构及多样性

为了解太湖鱼类群落结构和多样性的分布特征,于2009-2010年利用拖网等网具对该水域的鱼类资源进行了调查.结果表明:本次调查共采获鱼类50种,隶属10目15科40属,其中鲤形目种类最多,占总数的68％;鱼类生态类型以湖泊定居性种类为主,群落优势种为湖鲚(Coilia ectenes taihuensis)、间下鱵(Hyporhamphus intermedius)和陈氏短吻银鱼(Salangichthys jordani)等小型鱼类;与历史资料相比,太湖鱼类的物种数量下降,优势种组成发生较大变化,鱼类群落中体质量＜30 g的小型鱼类占绝对优势,渔业资源小型化趋势明显.由于过度捕捞和湖泊环境恶化,鱼类群落生物多样性指数均表现偏低,物种丰富度指数D为1.54,多样性指数H’N、H’w分别为0.21和0.46,均匀度指数J'N、.J'w分别为0.07和0.14;太湖各湖区间鱼类种群和多样性的差别一定程度上反映出鱼类群落结构与湖泊营养盐、透明度等环境特征相适应的特点.     

Species composition and pattern of fish distribution in Siberia

At the end of the first half of the 20th century, 61 species and subspecies of fish, including one invader (bleak Alburnus alburnus) and 17 species—endemics of Baikal—were reported for Siberia (Berg, 1933, 1949). At the present time, in rivers, lakes, and reservoirs of Siberia, 96 fish species and subspecies are described, of which 80 are aboriginal and 16 are invaders; 33 species are endemics of Baikal. Each landscapegeographic zone of Siberia has its specific ichthyofauna: in rivers and lakes of the south of Siberia, species of boreal piedmont complex dominate; in water bodies of the steppe, forest-steppe, taiga, and southern parts of the forest-steppe zone boreal plain dominates; in the zone of tundra, arctic freshwater dominates; and in Baikal, the most part (35) of species belongs to the Baikal autochtonous complex. Most researchers, as before, distinguish in Siberia two ichthyogeographic sites—West Siberian and East Siberian—that enter the Arctic Province of the Circumpolar subregion of the Holarctic region. Baikal is considered in the rank of the suboblast of the Holarctic.