长江中下游湖泊软体动物的多样性及分布现状

长江中下游流域是我国淡水贝类多样性最为集中的地区,然而由于人类活动的影响,淡水贝类已成为高度濒危的类群。为有效保护淡水贝类的多样性,我们于2003年6月-2005年5月对长江中下游流域13个水体软体动物的多样性及分布进行了调查。共采集到软体动物69种(中国特有种42种),隶属于腹足类9科14属29种和瓣鳃类5科17属40种。其中,蚌科和田螺科是种类数最多的两个科,分别占总种类数的50.7%和14.5%。不同类型湖泊软体动物种类数的差别较大。通江湖泊所占种类数相对丰富,尤其是适应流水的种类,如河螺属、短沟蜷属及蚌科的种类。大型通江湖泊鄱阳湖和洞庭湖软体动物的种类数和特有种数分别66种和40种,分别占总种类数和总特有种数的95.7%和95.2%。阻隔水体所占种类数相对较少,种类数为4-19种。与历史资料相比,长江中下游湖泊软体动物的种类数和特有种数均减少50%左右,且多数种类的分布范围也明显缩小。造成贝类资源衰退的可能原因主要是江湖阻隔所引起的整个江湖复合系统栖息地和水文情势的改变,其他的人为活动如过度捕捞、围垦及废污水的过度排放等也可能是其中的重要原因。     

Biogeography and conservation of aquatic fauna in spring-fed tropical canyons of the southern Sonoran Desert,Mexico

In arid regions, spring-fed habitats are frequently the only year-round source of surface water and are essential habitats for aquatic organisms and primary water sources for terrestrial animals and human settlements. While these habitats have been relatively well-studied in some regions, those of the southern Sonoran Desert have received little attention. In 2008 and 2009, we documented the biodiversity of aquatic animals at 19 sites across three arid mountain ranges in Sonora, Mexico, characterized macrohabitat types, examined seasonal variation in aquatic invertebrate communities, and explored the effects of an exotic fish (tilapia) on native communities. We documented >220 aquatic animal species, including several new species and range extensions for others. Macrohabitat type (oasis, tinaja, riffle, and seep) was more important than geographic location in structuring aquatic invertebrate communities at the scale of our study area (~9,000 km²). We found little evidence of predictable seasonal variation in invertebrate communities, despite dramatic hurricane-induced flooding. Aquatic vertebrates were not diverse across the study region (4 amphibian species and 2 species each of fishes and reptiles), but were often locally abundant. Presence of non-native tilapia at one site was associated with reduced abundances of native leopard frogs and reduced richness and density of native aquatic invertebrates. The most pressing aquatic habitat conservation concerns in the region, as in other deserts, are groundwater withdrawal, unmanaged recreational visitation, and the introduction of exotic species. Spring-fed habitats around the world have been called hotspots of freshwater biodiversity, and those of the Sonoran Desert are no exception.     

江西井冈山自然保护区陆生贝类多样性

2011年4～8月调查了江西井冈山自然保护区陆生贝类资源,共采得陆生贝类67种和亚种(含9个未定种),隶属4目19科31属,其中有1新种,即龙潭弯螺(Sinoennea sp.nov.)(另文报道);14种为江西省陆生贝类新纪录种;优势种为长柱倍唇螺(Diplommatina paxillus longipalatalis)、细锥倍唇螺(D.apicina)、灰尖巴蜗牛(Bradybaena ravida ravida)、双线巨蓬蛞蝓(Meghimatium bilineatum)。区系组成以东洋界成分为主,占种类总数的74.14%。阔叶林、灌木丛和农田生境陆生贝类种类较丰富,竹林和苔藓生境种类较少。根据调查数据,分别计算井冈山自然保护区5种不同生境类型中陆生贝类群落的多样性、丰富度和均匀度,结果表明,灌木丛生境陆生贝类的丰富度指数和多样性指数均最高,苔藓生境的均匀度指数最高。与邻近自然保护区比较,井冈山自然保护区陆生贝类物种较丰富,且与江西齐云山陆生贝类物种相似系数较高,与广东南岭物种相似系数较低。     

Global meta‐analysis of native and nonindigenous trophic traits in aquatic ecosystems

Ecologists have recently devoted their attention to the study of species traits and their role in the establishment and spread of nonindigenous species (NIS). However, research efforts have mostly focused on studies of terrestrial taxa, with lesser attention being dedicated to aquatic species. Aquatic habitats comprise of interconnected waterways, as well as exclusive introduction vectors that allow unparalleled artificial transport of species and their propagules. Consequently, species traits that commonly facilitate biological invasions in terrestrial systems may not be as represented in aquatic environments. We provide a global meta‐analysis of studies conducted in both marine and freshwater habitats. We selected studies that conducted experiments with native and NIS under common environmental conditions to allow detailed comparisons among species traits. In addition, we explored whether different factors such as species relatedness, functional feeding groups, latitude, climate, and experimental conditions could be linked to predictive traits. Our results show that species with traits that enhance consumption and growth have a substantially increased probability of establishing and spreading when entering novel ecosystems. Moreover, traits associated with predatory avoidance were more prevalent in NIS and therefore favour invasive species in aquatic habitats. When we analysed NIS interacting with taxonomically distinctive native taxa, we found that consumption and growth were particularly important traits. This suggests that particular attention should be paid to newly introduced species for which there are no close relatives in the local biota. Finally, we found a bias towards studies conducted in temperate regions, and thus, more studies in other climatic regions are needed. We conclude that studies aiming at predicting future range shifts should consider trophic traits of aquatic NIS as these traits are indicative of multiple interacting mechanisms involved in promoting species invasions.     

Systematic review of the land snails of the Pitcairn Islands

The land snails (and semi-terrestrial molluscs) of the four islands that comprise the Pitcairn group are reviewed and the indigenous species illustrated. The strictly terrestrial molluscan faunas from the two atolls (Oeno and Ducie) are poor, like many other atolls in the Pacific. Each supports less than six species with wide geographical ranges. In contrast, the terrestrial molluscan fauna from Henderson Island, an uplifted atoll, is more diverse with at least 16 species belonging to seven families. Over half these taxa appear to be endemic, at least at the level of sub-species. Two species of semi-terrestrial molluscs have also been found on Henderson. Analyses of archaeological deposits in caves near the North Beach have revealed that at least a further six species of land snail formerly occurred on Henderson. The volcanic island of Pitcairn, the only island in the group still inhabited, supports the greatest number of terrestrial molluscs. Twenty-six species of land snail (and one semi-terrestrial pulmonate) were found living there during the recent expedition and a further three taxa were recognized amongst museum material. At least seven of these species are thought to be recent adventives and a further three are likely to have been prehistoric introductions. One Henderson (Georissa hendersoni) and three Pitcairn endemics (Pacificella filica, Sinployea pitcaimensis and Diastole tenuistriata) are formally described as new species. Some of the Pitcairn endemics occur in very restricted areas (less than a hectare) and it is important that measures should be taken to prevent the spread of invasive plants, such as rose-apple, that would threaten their survival.     

长江流域淡水软体动物物种多样性及其分布格局

研究以正式发表的淡水软体动物文献和部分未发表野外调查数据为基础资料,分析了长江流域淡水软体动物物种多样性及分布格局。长江流域已报道的软体动物有296种,隶属17科62属,其中有197种是中国特有种。田螺科、肋蜷科、盖螺科、椎实螺科和蚌科是长江流域软体动物的主要组成部分,这5科种类数之和达249种,占总数的84.1%。从总体上低海拔地区的软体动物物种数高于高海拔地区,而高海拔地区特有种所占的比例却高于低海拔地区。支流和湖泊的种类数接近,分别为202种和210种,远高于长江干流（31种）。各水系软体动物的种类数、特有种数及特有种比例明显不同,洞庭湖水系和鄱阳湖水系的多样性最高。聚类分析表明,长江流域软体动物的分布基本反映了流域内的地势特点,形成了高原、中低海拔山地和低海拔平原的分布格局。不同类群的物种其分布格局也不相同,田螺科和椎实螺科的分布范围较广,肋蜷科和盖螺科种类分布范围狭窄,多数种类仅存在于单个水系,蚌科种类分布最为集中,以鄱阳湖和洞庭湖的种类最为丰富,种类数分别为58种和45种。研究表明,金沙江下游（云贵高原湖泊）、鄱阳湖和洞庭湖软体动物物种多样性丰富,建议将其列为我国淡水软体动物急需关注和保护的热点地区。       

Algae-associated marine molluscs in the Azores

The raolluscan fauna of a special habitat, the high intertidal algal turf, was studied at four stations on the island of Sao Miguel, Azores. The number of species found ranged from 13 to 23. However, a small group of only six species (the bivalve Lasaea adansoni and the gastropods Pisinna punctulum, Omalogyra atomus, Fossarus ambiguus, Skeneopsis planorbis and Alvania postrema) accounted for more than 80% of all the specimens collected. Mollusc density reached values of 20000 specimens per 100 g algal dry weight. The abundance and number of species of molluscs was comparable with those reported for algal zones lower on the Azorean shores.
Wave exposure and seasonality effects were found to be small, presumably because of the relatively mild abiotic conditions and the protective role of the turf. The algal substrata influenced the phytal molluscan community in two ways. First, the abundance of molluscs was significantly correlated with algal dry weight. Secondly, molluscan abundance and diversity were influenced by the algal composition of the turf. A rich algal composition, with several species of branched fleshy and coralline algae, was associated with a rich molluscan fauna. The dominance of coralline algae resulted in a abundant but species-poor fauna, while an almost monospecific turf of Gigartina was poor in both species and number of molluscan fauna.     

Trophic ecology of a top predator colonizing the southern extreme of South America: Feeding habits of invasive American mink (Neovison vison) in Tierra del Fuego

The American mink (Neovison vison) is a semi-aquatic, generalist carnivore released onto Tierra del Fuego (TDF) Island in the 1940s, subsequently spreading to adjacent islands in the archipelago with potential effects on native prey populations. Knowledge of this new predator's trophic ecology is essential to identify threats, plan control strategies and conserve native fauna. We studied seasonal mink diet in TDF in different habitats. We identified undigested remains from 493 scats collected between May 2005 and March 2009 along marine coasts and freshwater shores (rivers and lakes). Small mammals and fish were the main mink prey in TDF (over 65% of diet items). Seasonal variations were not detected, but diet did vary significantly between marine and freshwater habitats, where more terrestrial items were consumed. Among mammals, mink consumed more small native rodents than exotic species. Native fish consumption was also important with greater representation of species from the families Nototheniidae and Galaxiidae in marine and freshwater habitats respectively. Birds were the third item in importance, but did not constitute a particularly large part of the mink's diet on TDF. Overall, differences found in mink diet between habitats reflected their generalist/opportunistic feeding behaviour and did not differ greatly from observations in its native range or in other areas where it has been introduced. Our results establish the interactions between this novel predator and its prey and also illustrate the need to continue research on native prey populations to quantify mink impact on them and understand the ecological context of this biotic assemblage.     

Marine invasions by non-sea snakes, with thoughts on terrestrial-aquatic-marine transitions

Few species of snakes show extensive adaptations to aquatic environments and even fewer exploit the oceans. A survey of morphology, lifestyles, and habitats of 2552 alethenophidian snakes revealed 362 (14%) that use aquatic environments, are semi-aquatic, or aquatic; about 70 (2.7%) of these are sea snakes (Hydrophiinae and Laticaudinae). The ancient and aquatic family Acrochordidae contains three extant species, all of which have populations inhabiting brackish or marine environments, as well as freshwater. The Homalopsidae have the most ecologically diverse representatives in coastal habitats. Other families containing species exploiting saline waters with populations in freshwater environments include: the Dipsadidae of the western hemisphere, the cosmopolitan Natricidae, the African Grayinae, and probably a few Colubridae. Species with aquatic and semi-aquatic lifestyles are compared with more terrestrial (fossorial, cryptozoic, and arboreal) species for morphological traits and life histories that are convergent with those found in sea snakes; this may provide clues to the evolution of marine snakes and increase our understanding of snake diversity.     

Paleoecological and isotopic analysis of fossil continental mollusks of Sandelzhausen (Miocene,Germany)

The fossil molluscan fauna of Sandelzhausen (Early/Middle Miocene, SE Germany) comprises a total of 44 species, mostly terrestrial pulmonate snails. Herein we present a paleoecological analysis of this fauna based on an actualistic approach and on data on stable isotopes of carbon and oxygen (assessed from specimens of the freshwater lymnaeid snail Galba dupuyiana and the terrestrial clausiliid snail Pseudidyla moersingensis). The paleoecological reconstruction achieved here is in line with previous works, with some novelties and minor modifications. The basal sediment layers point to a swampy area with ponds and/or oxbow lakes (closed system, as indicated by the covariation between oxygen and carbon isotopic signals of G. dupuyiana), prone to seasonal flooding events. This environment would then gradually transition into a perennial lake, as indicated by: the proportion of planorbids, the appearance of aquatic species intolerant to desiccation, and the decoupling of the covariation between oxygen and carbon isotopic signals of G. dupuyiana. The terrestrial habitat would have developed from a more open environment (semi-arid/sub-humid scrubland) to a sub-humid/humid denser forest afterwards. Still, species from drier and more open environments are present throughout all the layers, suggesting that these habitats persisted in the lake’s hinterland. The mean annual temperature, calculated from the oxygen isotopic composition of P. moersingensis, ranges from 18.5 to 20.5 °C, but with no significant trend of change throughout the layers.     

Concordant Biogeographic Patterns among Multiple Taxonomic Groups in the Mexican Freshwater Biota

In this paper we analyse the degree of concordance in species richness and taxonomic distinctness (diversity) patterns among different freshwater taxonomic groups in order to test three long held patterns described in Mexican freshwater biogeography: 1. The aquatic biota of Mexico includes two distinct faunas, a rich Neotropical component in the south and a south-eastern region and a less rich Nearctic component towards central and northern latitudes of the country. 2. A hotspot of species richness and diversity has been recorded in the Usumacinta, including the Yucatan Peninsula. 3. The presence of two distinct biotas in Mexico, an eastern one distributed along the Gulf of Mexico slope, and a western one associated to the Pacific versant. We use species richness and taxonomic distinctness to explore patterns of diversity and how these patterns change between zoogeographical regions. This paper points out a clear separation between Neotropical and Nearctic drainage basins but also between eastern (Gulf of Mexico) and western (Pacific) drainage basins. Present data gives additional empirical support from freshwater biota for three long held beliefs regarding distributional patterns of the Mexican biota. The neotropical basins of Mexico are generally host to a richest and more diversified fauna, that includes more families, genera and species, compared to the less rich and less diverse fauna in the nearctic basins.     

广东车八岭国家级自然保护区大型底栖动物多样性

大型底栖动物在当地生物多样性、食物链构成、水质指示和物质循环中有重要的作用, 但目前国内对森林内陆水体(湖泊、水库、溪流)中的大型底栖动物综合调查较少。作者于2019、2020年对广东车八岭国家级自然保护区的9个采样点开展了大型底栖动物的定性调查, 采样点涵盖保护区不同功能区、海拔、水体环境和水体底质。共鉴定出大型底栖动物4门6纲18目38科57种, 水生昆虫稚虫占大多数, 且多喜好清洁流动水体。在低海拔实验区即可采集到种类与数量可观的清洁水体指示物种。当地的大型底栖动物以亚热带森林典型物种为主, 多偏好栖息于流动水体, 反映了保护区的物种区系及其水体环境。本研究可为保护区的物种编目、环境评估和长期监测提供基础资料。     

Role of fungi in freshwater ecosystems

There are more than 600 species of freshwater fungi with a greater number known from temperate, as compared to tropical, regions. Three main groups can be considered which include Ingoldian fungi, aquatic ascomycetes and non-Ingoldian hyphomycetes, chytrids and, oomycetes. The fungi occurring in lentic habitats mostly differ from those occurring in lotic habitats. Although there is no comprehensive work dealing with the biogeography of all groups of freshwater fungi, their distribution probably follows that of Ingoldian fungi, which are either cosmopolitan, restricted to pantemperate or pantropical regions, or in a few cases, have a restricted distribution. Freshwater fungi are thought to have evolved from terrestrial ancestors. Many species are clearly adapted to life in freshwater as their propagules have specialised aquatic dispersal abilities. Freshwater fungi are involved in the decay of wood and leafy material and also cause diseases of plants and animals. These areas are briefly reviewed. Gaps in our knowledge of freshwater fungi are discussed and areas in need of research are suggested.     

Elevated native terrestrial snail abundance and diversity in association with an invasive understory shrub,Berberis thunbergii,in a North American deciduous forest

Invasive terrestrial plants often substantially reshape environments, yet how such invasions affect terrestrial snail assemblages remains understudied. We investigated how snail assemblages in deciduous forest soils with dense Berberis thunbergii (Japanese barberry), an invasive shrub in eastern North America, differ from forest areas lacking the shrub. Leaf litter and soil samples were collected from forest patches with dense B. thunbergii understories and adjacent control areas within two exurban forest tracts in western Pennsylvania, U.S.A. Snails were identified to species and quantified by standard diversity metrics. Contrary to our expectations, snails were significantly more abundant and diverse in B. thunbergii-invaded areas. Despite differences in abundance, the snail community composition did not differ between invaded and control habitats. The terrestrial snail assemblage we observed, which was composed entirely of native species, appears to respond favorably to B. thunbergii invasion and therefore may not be negatively impacted by physicochemical changes to soils typically observed in association with the plant. Such findings could reflect the fact that B. thunbergii likely creates more favorable habitat for snails by creating cooler, more humid, and more alkaline soil environments. However, the snail assemblages we retrieved may consist mostly of species with high tolerance to environmental degradation due to a legacy of land use change and acid deposition in the region.     

The feeding ecology of freshwater fishes in two rivers of the Australian wet tropics

Synopsis The fish fauna of the Mulgrave and South Johnstone rivers is diverse relative to other Australian rivers and this study examines the diets of many of the resident fish species. Most species were small (< 200 g), and although considerable overlap in the size of the mouth was observed, closely related species tended to have non-overlapping ranges in mouth size. Five trophic guilds were recognised and substantial discrimination between guilds on the basis of body size was noted. Small fishes (< 5 gm body weight) consumed a variety of insect larvae and small terrestrial insects. The diet of large fish was characterised by the presence of large aquatic invertebrates and fish. A third group of intermediate sized fishes (10–20 gm), which included the 0+ age class of three species of large fish, also consumed aquatic invertebrates but only a small proportion of terrestrial invertebrates. Vegetable material was present in the diet of all three guilds but the source of that material varied. In groups 1 to 3 above, the source of that material was desmids and diatoms, aquatic macrophytes or filamentous alga respectively. A fourth guild fed predominately on detritus and some bivalve molluscs, and a fifth group, containing only two species, fed feavily on gastropod molluscs. The extent of dietary overlap varied both within- and between-rivers. In habitats dominated by low water velocities and sandy substrates, resource partitioning was pronounced and the number of fishes with empty or near empty guts was high, suggesting that food was more limited in this type of habitats. Little resource partitioning was observed in habitats characterised by a coarse substrate, high water velocity and dense riparian canopy.     

Hawaiian biogeography and the islands' freshwater fish fauna

Aim This paper describes known patterns in the distributions and relationships of Hawaiian freshwater fishes, and compares these patterns with those exhibited by Hawaii's terrestrial biota. Location The study is based in Hawaii, and seeks patterns across the tropical and subtropical Indo‐west Pacific. Methods The study is based primarily on literature analysis. Results The Hawaiian freshwater fish fauna comprises five species of goby in five different genera (Gobiidae). Four species are Hawaiian endemics, the fifth shared with islands in the western tropical Pacific Ocean. All genera are represented widely across the Indo‐west Pacific. All five species are present on all of the major Hawaiian islands. All five species are amphidromous – their larval and early juvenile life being spent in the sea. Although there has been some local phyletic evolution to produce Hawaiian endemics, there has been no local radiation to produce single‐island endemics across the archipelago. Nor is there evidence for genetic structuring among populations in the various islands. Main conclusions In this regard, the freshwater fish fauna of Hawaii differs from the well‐known patterns of local evolution and radiation in Hawaiian Island terrestrial taxa. Amphidromy probably explains the biogeographical idiosyncrasies of the fish fauna – dispersal through the sea initially brought the fish species to Hawaii, and gene flow among populations, across the archipelago, has hitherto inhibited the evolution of local island endemics, apparently even retarding genetic structuring on individual islands.     

Threatened fishes in Australia–an overview

Considering the size of the continent, the Australian freshwater fish fauna is a relatively depauperate one, comprising only about 192 species (belonging to 34 families) which spend significant portions of their life cycles in freshwater habitats. Of these freshwater species, the latest (1989) analysis indicates that six can be classified as endangered, five as vulnerable, four as potentially threatened, two as indeterminate, 32 as restricted, and 16+ as of unknown status, totalling 65 + species. Thus approximately 34% of the entire Australian freshwater fish fauna falls within the above six conservation status categories, which were established by the Australian Society for Fish Biology in 1985. Conservation problems of these fishes, and particularly man-made changes to their habitats, are discussed, and some possible management solutions outlined. Brief mention is also made of several marine species which may also fall into one or more of the above conservation categories, although not enough information is yet available to classify them accurately.     

Urban ponds as an aquatic biodiversity resource in modified landscapes

Urbanization is a global process contributing to the loss and fragmentation of natural habitats. Many studies have focused on the biological response of terrestrial taxa and habitats to urbanization. However, little is known regarding the consequences of urbanization on freshwater habitats, especially small lentic systems. In this study, we examined aquatic macro‐invertebrate diversity (family and species level) and variation in community composition between 240 urban and 782 nonurban ponds distributed across the United Kingdom. Contrary to predictions, urban ponds supported similar numbers of invertebrate species and families compared to nonurban ponds. Similar gamma diversity was found between the two groups at both family and species taxonomic levels. The biological communities of urban ponds were markedly different to those of nonurban ponds, and the variability in urban pond community composition was greater than that in nonurban ponds, contrary to previous work showing homogenization of communities in urban areas. Positive spatial autocorrelation was recorded for urban and nonurban ponds at 0–50 km (distance between pond study sites) and negative spatial autocorrelation was observed at 100–150 km and was stronger in urban ponds in both cases. Ponds do not follow the same ecological patterns as terrestrial and lotic habitats (reduced taxonomic richness) in urban environments; in contrast, they support high taxonomic richness and contribute significantly to regional faunal diversity. Individual cities are complex structural mosaics which evolve over long periods of time and are managed in diverse ways. This facilitates the development of a wide range of environmental conditions and habitat niches in urban ponds which can promote greater heterogeneity between pond communities at larger scales. Ponds provide an opportunity for managers and environmental regulators to conserve and enhance freshwater biodiversity in urbanized landscapes whilst also facilitating key ecosystem services including storm water storage and water treatment.     

Freshwater snails of Oman,South Eastern Arabia

A systematic account is given of the extant freshwater snail fauna of Oman, based on recent collections made in Dhofar and in the northern mountainous areas. Also included are certain species found in brackish coastal localities. A total of 8 freshwater species is regarded as belonging to the fauna of normal freshwater; 7 have been found alive (Thiara scabra, Melanoides tuberculata, Lymnaea natalensis, Gyraulus piscinarum, Biomphalaria arabica, Bulinus wrighti and Indoplanorbis exustus) and one is known only as shells (Paludestrina glaucovirens). This report of G. piscinarum is the first for Oman and may be the first reliable identification for Arabia. Three taxa from brackish water, Gangetia miliacea, Iravadia quadrasi and Melanoides sp., are new for the fauna of Oman and of the whole Arabian peninsula. The finding of G. miliacea provides the first instance of any member of the Stenothyridae living west of the Gulf of Oman and identified from whole snails rather than empty shells. I. quadrasi is the first member of its genus to be found alive west of the Gulf of Oman.