An index of relative importance(IRI) was employed to screen for dominant fish in the waters surrounding the Taishan Islands, China, using data from four seasonal trawl surveys undertaken between 2012 and 2013. Niche b...An index of relative importance(IRI) was employed to screen for dominant fish in the waters surrounding the Taishan Islands, China, using data from four seasonal trawl surveys undertaken between 2012 and 2013. Niche breadth and niche overlap were measured using the Feinsinger and Morisita-Horn indices, respectively, and the characteristics and seasonal variations in the niches of dominant fish were assessed via non-metric multidimensional scaling(NMDS) and cluster analysis. A total of 80 fish species, including 16 dominant species, were recorded. Only A mblychaeturichthys hexanema was dominant in all seasons. According to niche breadth values and NMDS, the 16 dominant species were grouped into the following three types:(1) wide niche breadth species, including Cynoglossus macrolepidotus, A. hexanema, and Trypauchen vagina, among others;(2) medium niche breadth species, including Setipinna taty and Johnius belangerii; and(3) narrow niche breadth species, including A trobucca nibe and Coilia mystus. Most species with a wider niche breadth were demersal fish with a lower swimming capability and even distribution. The niche breadth of migrating fish was narrower than that of settled fish. At a given spatial scale, fish with stronger swimming capabilities had a narrower niche breadth. Niche overlap, which is associated with niche specialization, ranged from 0.000 to 0.886 and had an annual mean value of 0.314. In summer and autumn, niche overlap was relatively high within species of the Sciaenidae family and within species of the Gobiidae in autumn. Dif ferences in thermophily, feeding habits, food organism abundance/distribution and predator-prey relationships af fected the niche overlap of fish in this area. Cluster analysis revealed that species with the narrowest niche breadth and lowest niche overlap values usually displayed lower aggregation and greater distribution dif ferences compared with other species.展开更多
Since 2009, the newly recorded species Aureococcus anophagefferens has successively induced brown tides in the Qinhuangdao coastal waters of the Bohai Sea. Here, we focus on the phytoplankton community structure in th...Since 2009, the newly recorded species Aureococcus anophagefferens has successively induced brown tides in the Qinhuangdao coastal waters of the Bohai Sea. Here, we focus on the phytoplankton community structure in this region and try to point out the biological background characteristics of the outbreaks of successive brown tides. We analyzed species composition,cell abundance, diversity indices and size-fractionated chlorophyll a(Chl-a) concentration monthly from March 2013 to January2014. The phytoplankton community, as observed by microscopy, underwent succession from nano-celled chained diatoms to dinoflagellates in the spring and summer, and then to micro-celled diatoms and nano-celled chained diatoms as the most prominent groups in the subsequent autumn and winter. Canonical correspondence analysis revealed that changes in the abundance of diatoms were related to nutrient availability, especially of nitrogen, while water temperature was the crucial factor influencing the abundance of dinoflagellates and A. anophagefferens. Considering the contribution of nano-celled chained species to the micro-sized Chl-a,small phytoplankton(<20 μm) composed the majority of total Chl-a and were generally abundant during our study. Abundant and diverse small phytoplankton seemed to serve as a background or seedbank for the formation of blooms of A. anophagefferens and other small-celled algae.展开更多
基金Supported by the National Natural Science Foundation of China(No.41106073)the Technology R&D Program of Fujian Provincial Department of Ocean and Fisheries(No.2012013)
文摘An index of relative importance(IRI) was employed to screen for dominant fish in the waters surrounding the Taishan Islands, China, using data from four seasonal trawl surveys undertaken between 2012 and 2013. Niche breadth and niche overlap were measured using the Feinsinger and Morisita-Horn indices, respectively, and the characteristics and seasonal variations in the niches of dominant fish were assessed via non-metric multidimensional scaling(NMDS) and cluster analysis. A total of 80 fish species, including 16 dominant species, were recorded. Only A mblychaeturichthys hexanema was dominant in all seasons. According to niche breadth values and NMDS, the 16 dominant species were grouped into the following three types:(1) wide niche breadth species, including Cynoglossus macrolepidotus, A. hexanema, and Trypauchen vagina, among others;(2) medium niche breadth species, including Setipinna taty and Johnius belangerii; and(3) narrow niche breadth species, including A trobucca nibe and Coilia mystus. Most species with a wider niche breadth were demersal fish with a lower swimming capability and even distribution. The niche breadth of migrating fish was narrower than that of settled fish. At a given spatial scale, fish with stronger swimming capabilities had a narrower niche breadth. Niche overlap, which is associated with niche specialization, ranged from 0.000 to 0.886 and had an annual mean value of 0.314. In summer and autumn, niche overlap was relatively high within species of the Sciaenidae family and within species of the Gobiidae in autumn. Dif ferences in thermophily, feeding habits, food organism abundance/distribution and predator-prey relationships af fected the niche overlap of fish in this area. Cluster analysis revealed that species with the narrowest niche breadth and lowest niche overlap values usually displayed lower aggregation and greater distribution dif ferences compared with other species.
基金supported by the National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers (Grant No. U1606404)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA11020601)the Public Science and Technology Research Funds Projects of Ocean (Grant No. 201305003-3)
文摘Since 2009, the newly recorded species Aureococcus anophagefferens has successively induced brown tides in the Qinhuangdao coastal waters of the Bohai Sea. Here, we focus on the phytoplankton community structure in this region and try to point out the biological background characteristics of the outbreaks of successive brown tides. We analyzed species composition,cell abundance, diversity indices and size-fractionated chlorophyll a(Chl-a) concentration monthly from March 2013 to January2014. The phytoplankton community, as observed by microscopy, underwent succession from nano-celled chained diatoms to dinoflagellates in the spring and summer, and then to micro-celled diatoms and nano-celled chained diatoms as the most prominent groups in the subsequent autumn and winter. Canonical correspondence analysis revealed that changes in the abundance of diatoms were related to nutrient availability, especially of nitrogen, while water temperature was the crucial factor influencing the abundance of dinoflagellates and A. anophagefferens. Considering the contribution of nano-celled chained species to the micro-sized Chl-a,small phytoplankton(<20 μm) composed the majority of total Chl-a and were generally abundant during our study. Abundant and diverse small phytoplankton seemed to serve as a background or seedbank for the formation of blooms of A. anophagefferens and other small-celled algae.
