象山港春、夏季大中型浮游动物空间异质性

Abstract

Spatial heterogeneity refers to non-uniformity and complexity of spatial distribution in ecological systems,and is generally regarded as the sum of patchy and gradient distribution patterns.The concept of spatial heterogeneity has long been applied to the field of ecology,but was introduced later in the marine environment because of the complexity caused by water fluidity and the weak motility of plankton.However,spatial heterogeneity of the marine environment is crucial to the diversity of structure and function of marine communities.Thus,spatial heterogeneity of plankton communities has been frequently discussed by marine ecologists.To investigate the spatial distribution of macro-and meso-zooplankton in Xiangshan Bay,the zooplankton community and associated environmental factors were investigated at neap and spring tide in April and July 2010.Using a shallow water type I plankton net,seventeen tows from the inner bay to the outer bay were conducted on each sampling occasion.Water quality parameters including:temperature,salinity,depth,p H,waterclarity,dissolved oxygen,suspended solid concentrations and nutrient levels were also measured.A total of 64 adult zooplankton species representing fourteen taxa,and fourteen planktonic larval species from ten taxa were identified from the four cruises.Species composition changed 66.7% between spring and summer.While brachyuran zoea and larval fish were dominant in both seasons,other dominant species changed between the two seasons resulting in a significant difference(P= 0.001) in community structure.Species similarity between neap tide and spring tide was about 60% within the same season(P = 0.031).Biomass and abundance was higher in spring than in summer,while species diversity was lower.Temperature was the main factor which influenced seasonal variation in zooplankton.Analysis of variance,community clustering and non-metric multi-dimensional scaling analyses showed that the distribution framework of the zooplankton community was influenced by tide.Community structure exhibited a stronger gradient during spring tide,and was patchily distributed during neap tide.Community structure determined patterns of distribution,but this was influenced by differences in biomass,abundance and diversity inside and outside the mouth of Xiangshan Bay.Canonical correspondence analysis and regional analysis of environmental parameters showed that gradients in distribution were mainly determined by salinity and suspended solids.The main environmental parameters associated with patchiness included depth,chlorophyll a concentration,nutrients and the interaction of water masses in and out of Xiangshan Bay under different conditions.Gradient and patchiness patterns of zooplankton distribution were both influenced by the tide.The spatial distribution of zooplankton in Xiangshan Bay was strongly influenced by hydrological factors,and weakly influenced by chemical and biological factors.Zooplankton abundance and chlorophyll a concentration were correlated during spring.Water quality parameters including dissolved oxygen,p H and nutrient levels had little direct influence on the spatial distribution of zooplankton in the bay.