ABSTRACT

Introduced species often have negative effects on native species that occupy the same habitats in the area of introduction. Habitat preferences of organisms can therefore play a large role in determining the severity of interactions such as competition or predation. Previous laboratory studies have shown that the introduced mussel species Perna viridis can decrease the settlement and early survival of the native oyster species Crassostrea virginica. Both species can often be found in the same general areas, but it is unknown whether this habitat overlap is complete, or whether there are certain locations that may act as refuges for native bivalve species. The present study investigated the settlement patterns of the introduced P. viridis and two groups of native bivalves, oysters (C. virginica and Ostrea equestris) and mussels (Ischadium recurvum, Brachidontes exustus and Geukensia demissa), to determine whether preferential settlement depths and habitats differed among the groups. Most of these groups showed significantly greater settlement on deeper substrates that were located in the main channel of the Atlantic Intracoastal Waterway of northeast Florida. While native oysters also settled in adjacent feeder creeks in fairly large numbers, settlement of P. viridis in these areas was relatively rare. In main channel locations, the overlap in settlement depth is likely to result in competition between introduced and native bivalve species, but feeder creeks may provide areas of refuge for native oysters. The spatial and temporal overlap of all three groups suggests that competition among nonnative and native bivalves may occur in nature.

中文翻译：

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原生和非原生的双壳类动物定居：东北佛罗里达河口空间资源的潜在竞争

摘要

引进的物种通常会对在引进地区占据相同栖息地的本土物种产生负面影响。因此，生物的栖息地偏好可以在确定相互作用的严重性（例如竞争或掠食）中发挥重要作用。先前的实验室研究表明，引进的贻贝物种Perna viridis可以减少本地牡蛎物种Crassostrea virginica的沉降和早期存活。这两种物种通常都可以在同一地区找到，但尚不清楚该栖息地重叠是否完整，或者是否存在某些位置可能成为本地双壳类物种的避难所。本研究调查了引入的P. viridis的沉降模式以及两组原生的双壳类牡蛎（牡蛎（C. virginica和Ostrea equestris））和贻贝（Ischadium recurvum，Brachidontes exustus和Geukensia demissa），以确定两组之间优先的定居深度和栖息地是否有所不同。这些组中的大多数在位于佛罗里达东北部大西洋沿海内河航道主要航道的较深基底上显示出明显更大的沉降。虽然本地牡蛎也大量栖息在相邻的接食河中，但是绿脓杆菌的栖息地在这些地区相对罕见。在主要航道位置，定居深度的重叠很可能导致引进的双壳类和本地双壳类之间的竞争，但饲养小河可能为本地牡蛎提供庇护区。这三类动物在空间和时间上的重叠表明，自然界中可能发生外来和自然双壳类动物之间的竞争。