Fish persistence and fluvial geomorphology in central Australia     

Peter J. Unmack 《Journal of Arid Environments》2001,49(4):653

The purposes of this paper are to document the composition and distribution of fishes in the Alice Springs region of Australia, and discuss constraints on fish persistence in this arid region. Nine native and six exotic species were recorded; most exotics no longer exist. Except in Finke River, only one or no native species were found. Fish survival in the area is ameliorated by the exceptionally broad environmental tolerances and migratory abilities of many species, but ultimately depends upon the effects of geology, geomorphology, and the vagaries in pattern of sediment transport on water persistence.  相似文献   

Scale-dependent patterns of abundance and habitat use by cormorants in arid Australia and the importance of nomadism     

E. J. Dorfman  R. T. Kingsford 《Journal of Arid Environments》2001,49(4):677

We investigated the ways in which cormorants (Phalacrocorax spp.) acquire behavioural cues from unpredictable habitats in arid Australia, using 10 years of temporal data on abundance at one wetland, fine-grained habitat and microhabitat use at two wetlands, and broad-scale spatial data from aerial surveys across north-west New South Wales. Abundances were highly variable and cormorants were aggregated at every temporal and spatial scale of observation. Cormorants were associated with short-term patches of food, and apparently travel frequently in a quest for newly formed patches. Movements and abundance of cormorants are linked to boom periods of their prey, and, like many Australian waterbirds, cormorants would benefit from improved water management practices.  相似文献   

Selection of nursery areas by six southeast African Penaeidae     

A. J. de Freitas 《Estuarine, Coastal and Shelf Science》1986,23(6)

A survey was carried out along the shore and adjacent mangrove swamp in the northeast margin of Maputo Bay in Mozambique, east Africa. The study area contained several habitats within close proximity. These were shallow pools in the intertidal muddy sand flats, areas of submerged macrophytes, the swash zone on sandy beaches, primary mangrove channels, secondary mangrove channels, shallow mangrove creeks and a shallow creek with strong freshwater influence at the landward fringe of the swamp. Each station was sampled by means of a small handnet. Data suggest that Penaeus japonicus prefers sandy substrata, while P. semisulcatus chooses areas rich in submerged macrophytes. P. indicus and P. monodon both appear to favour muddy mangrove channels, although P. monodon may require marginal or floating vegetation as nurseries. Metapenaeus stebbingi seems to prefer the swash zone in quiet areas with minimal wave action, while M. monoceros is more widespread and is able to cope with very low salinities. Managers of coastal systems should, therefore, attempt to maintain a diversity of biotopes within larger systems because, even if postlarvae do enter an estuary, juvenile populations with not develop if their specific habitat has been destroyed.  相似文献   

Food and habitat resource partitioning between three estuarine fish species on the Swedish west coast     

Staffan Thorman 《Estuarine, Coastal and Shelf Science》1983,17(6)

In 1978 the food and habitat resource partitioning of three small and common fish species, viz. Pomatoschistus microps (Krøyer), Gasterosteus aculeatus (L.) and Pungitius pungitius (L.) were studied in river Broälven estuary on the Swedish west coast (58°22′N, 11°29′E). The area was divided into three habitats, based on environmental features. In July, September, and October stomach contents and size distribution of each species present were analysed.In July there was high food and habitat overlap between the species. Interference interactions probably occurred between some size classes of P. microps and the other two species. P. pungitius was exposed to both intra- and interspecific interactions. In September the food and habitat overlaps between G. aculeatus and P. pungitius were high, while both had low food and habitat overlaps in relation to P. microps. Interactions between G. aculeatus and P. pungitius were probably influenced by more severe abiotic conditions in one habitat, which caused lower abundances there, and higher abundances in the other two habitats. In October no interactions were observed. These results indicate that competition for food at least temporarily determines the species distribution in a temperate estuary, and that estuarine fish populations are sometimes food limited.  相似文献   

Niche characterization of dominant estuarine benthic species     

R. Warren Flint  Richard D. Kalke 《Estuarine, Coastal and Shelf Science》1986,22(6)

Benthic macroinfaunal species in a south Texas estuarine environment were studied over a 2·5 year period to characterize their distributions and ecology. The 13 dominant taxa chosen for investigation exhibited distinct habitat usage differences as judged both by the use of discriminant analysis and the differentiation of behavioral characteristics. Species coexistence in the estuarine bethic community of Corpus Christi Bay was examined with respect to resource partitioning for such parameters as food and space. Utilization of these resources by the dominant taxa differed in both temporal and spatial dimensions, with the spatial dimension consisting of horizontal and vertical attributes. Benthic species were separated according to (1) occurrences in certain sediment types with varying organic content, (2) presence in estuarine regions characterized by different phytoplankton productivity rates, (3) different periods of annual occurrence, and (4) occurrence in different sediment microhabitats characterized by varying sediment depth and relation to depth of oxygenated sediments. Superimposed upon differences in habitat usage of these species were behavioral traits, such as feeding differences, which further discriminated how benthic species obtained resources. Based upon species occurrence in a certain characteristic environment, we speculated on the structural division of the benthic habitat by various taxa often classified as common members of the same species' assemblages in the past. Although other investigators have demonstrated interactions among co-occurring benthic infaunal species, the information presented here illustrated how these species could minimize interactions in order to maintain their populations.  相似文献   

Late glacial impacts on dispersal and colonization of Atlantic Canada and Maine by freshwater fishes     

R. Allen Curry 《Quaternary Research》2007,67(2):225-233

Late glacial scenarios of ice retreat and biogeography databases constrain the dispersal routes of obligate freshwater fishes into Atlantic Canada and Maine. Evidence indicates glacial ice covered the present-day mainland and offshore islands at 18,000 ¹⁴C yr before present. Possible refugia for extirpated freshwater fishes were the exposed outer edge of the Grand Banks (east), exposed Georges Bank (south-Atlantic Refugium), and the Mississippi Refugium in the west. It is improbable that the region was recolonized from the offshore refugia. Rather, fishes recolonized from the east via the upper St. Lawrence River valley into the upper Saint John River, Maine (Lake Madawaska) from 11,000 to 12,000 ¹⁴C yr BP. The short period of entry resulted in the low diversity of obligate freshwater species in the region. Lake Madawaska was breached and dispersal continued into the remainder of the region after 8000 ¹⁴C yr BP. By 6000 ¹⁴C yr BP, access routes to the east along low-lying coastal zones were blocked by rising sea levels, which isolated Prince Edward Island, Cape Breton Island, and most probably Nova Scotia. Natural dispersal across the region appeared complete by this time.  相似文献   

干旱、半干旱区几种典型生境蛴螬群落特征比较研究   总被引：2，自引：1，他引：1  

刘新民  郭砺  乌宁  刘心亮  刘永江 《中国沙漠》2001,21(3):250-253

1998- 1999年,对我国北方干旱、半干旱区几种典型生境(腾格里沙漠生态系统、内蒙古典型草原、科尔沁沙地)的蛴螬群落作了比较研究,结果表明:东方绢金龟(Serica orientalis Motschulsky)在3个采样区的优势度均为最高,3个采样区蛴螬群落的次优势种相互间有差别,内蒙古典型草原多为黑皱鳃金龟(Trematodes tenebrioides(Pallas))和弓斑常丽金龟(Cyriopertha arcuata(Gebler)),科尔沁沙地为黄褐异丽金龟(Anomala exoleta Faldermann)和灰胸突鳃金龟(Hoplosternus incanus Otschulsky),腾格里沙漠生态系统为黄褐异丽金龟(Anomala exoleta Faldermann)。腾格里沙漠生态系统蛴螬群落组成单调、密度极低是不言而喻的,科尔沁沙地蛴螬群落密度不如内蒙古典型草原高,多样性指数是最高的。就3个样区蛴螬群落的相似性而言,科尔沁沙地与内蒙古典型草原的相似性要低于与腾格里沙漠生态系统的相似性。  相似文献   

Current Status of Scientific Deep-diving Investigations in Submarine Canyons     

Guangfa Zhong 《地球科学进展》2019,34(11):1111-1119

Submarine canyons represent one of the most important geomorphologic features in continental margins, act as one of the most important conduits of seafloor sediment transporting from shallow waters into the deep sea, and are also biodiversity hotspots. Submarine-canyon investigations are therefore significant for seafloor scientific research, submarine mineral and resource exploitation, and the construction and safety operation of submarine infrastructures. Deep-sea diving by manned submersibles and robot submersibles represented by Remotely Operated Vehicles (ROV) and Autonomous Underwater Vehicles (AUV) provides an important approach to the investigation of modern submarine canyons. The biggest advantage of manned submersibles is that they can bring scientists to the deep sea for in-place observations and precise sampling, while the robot deep-sea diving has the advantages of low cost, high efficiency, no personnel safety concerns, and the ability to reach the extreme sea areas that are difficult for humans to reach. Deep-sea diving has found broad applications in the geo-scientific research of submarine canyons. These studies cover seafloor topography and geomorphology, seafloor sediments, erosional and depositional bedforms, mass transport processes and flow dynamics, cold springs, cold-water corals and other biological habitats, as well as seafloor biological erosion. The research experience and scientific findings in scientific diving investigation of submarine canyons accumulated by the developed countries in Europe and the United States over the past 70 years are of great reference and significance to the emerging scientific deep-sea diving in China.  相似文献   

荒漠绿洲边缘凝结水量及其影响因子   总被引：16，自引：0，他引：16  

方静  丁永建 《冰川冻土》2005,27(5):755-760

以2004年7~10月在临泽内陆河流域综合研究站凝结水试验观测数据为基础,讨论了荒漠绿洲边缘凝结水凝结过程、不同下垫面凝结量及其影响因子.结果表明:荒漠绿洲边缘凝结水以吸湿凝结为主,北京时间16:00~18:00开始,至次日7:00~8:00结束.凝结开始的时间受控于沙地含水量,凝结量则主要受近地表相对湿度、近地表气温以及气温日较差三方面因素的影响.人工草地、平坦无植被沙地、沙丘顶部、丘间低地和人工林地在7~10月的平均月凝结量分别为:5.1 mm、4.0 mm、3.1mm、1.8 mm和1.0 mm.  相似文献   

Biometric analysis of lacustrine and riverine populations of Palemonetes antennarius (H. Milne-Edwards, 1837) (Crustacea, Decapoda, Palaemonidae) from north-western Greece     

Chryssa Anastasiadou  Roman Liasko  Ioannis D. Leonardos   《Limnologica》2009,39(3):244-254

Comparative study of morphometric measurements was undertaken on populations of Palaemonetes antennarius from two freshwater habitat zones (lacustrine pelagic and lacustrine littoral) and from the fluvial littoral habitat zone of three estuaries of north-western Greece. Multivariate statistical analyses (principal component analysis and discriminant function analysis) revealed clear morphometric differences between sexes and sampling sites. The observed differences are expressed mainly thought the measurements related to the body heights (carapace height and second pleon height), as a result of sexual dimorphism, High values for the female body heights seem to be correlated to specific fecundity profile and reproductive strategy. On the other hand, morphometrical variables related mainly to body lengths, such as rostral, telson and pleon lengths, were observed to be correlated to the study sites. Characters related to the summing capacity (telson length, telson width and pleon lengths) were generally found to have higher values in the specimens from habitats with high reophilic profile.  相似文献