缢蛏混养对三疣梭子蟹-日本囊对虾综合养殖系统理化环境和小型底栖动物的影响

滤食性贝类在生态系统中可通过自身生理活动促进系统的物质循环和能量流动,进而影响养殖环境。为从养殖系统底质环境角度为综合养殖系统优化提供依据,建立了4个实验生态系统,即在三疣梭子蟹-日本囊对虾养殖系统中混养3个不同密度的缢蛏(由低到高分别表示为PMB₁,PMB₂,PMB₃),并以三疣梭子蟹-日本囊对虾养殖系统(PM)为对照。通过对不同养殖系统底泥理化性质及小型底栖动物丰度、生物量的比较分析,探究缢蛏不同混养密度对养殖系统底质环境的影响。结果显示,总体而言,试验期间缢蛏高密度混养系统PMB₃底泥pH与氧化还原电位(ORP),显著高于其他系统,而底泥有机质含量显著低于其他系统。从小型底栖动物群落物种组成来看,不同养殖系统中线虫在丰度上占主要优势,占总丰度的35.9%~42.7%;介形类在生物量上占最大优势,占总生物量的74.2%~81.1%,PMB₃总丰度和总生物量显著高于其他系统。较高混养密度下,缢蛏能通过滤食残饵、粪便等有机物减少底泥有机物质的积累,改善底质环境,提高小型底栖动物丰度和生物量。本试验条件下,根据养殖系统底质环境变化特征,缢蛏放养密度34.7×10⁴ ind./hm²为最优放养密度。

EFFECTS OF SINONOVACULA CONSTRICTA POLYCULTURE ON SEDIMENTARY ENVIRONMENT IN THE INTEGRATED CULTURE SYSTEM OF PORTUNUS TRITUBERCULATUS AND MARSUPENAEUS JAPONICUS

To optimize the integrated aquaculture system from the perspective of sedimentary environment of aquaculture system, four experimental aquaculture systems were established, i.e., polyculture systems of Portunus trituberculatus and Marsupenaeus japonicus in three stocking densities (low, middle, and high) of Sinonovacula constricta (PMB₁, PMB₂, and PMB₃, respectively), and polyculture system of P. trituberculatus and M. japonicus (PM). By comparing and analyzing the physical and chemical properties of sediment, the abundance and biomass of small benthos in different aquaculture systems and the effects of stocking densities of S. constricta on the sedimentary environment of aquaculture systems were determined. Results show that, in general, the pH and redox potential of sediment in the high-density system (PMB₃) were significantly higher than those in other systems, while the content of organic matter in sediment in PMB₃ was significantly lower than those in other systems. As the composition of benthic community shows, nematodes are dominant in abundance, accounting for 35.9%~42.7% in different systems, and Ostracods accounted for 74.2%~81.1% of the total biomass in different systems. The total abundance and biomass in PMB₃ were significantly higher than those of other systems. At higher culture density, S. constricta could reduce the accumulation of organic matter in sediment by filtering the residuals and feces, and thus may improve the sedimentary environment and increase the abundance and biomass of small benthos. Based on the characteristics of sedimentary environment in different systems, the optimal stocking density of S. constricta was 34.7×10⁴ ind./hm² under the present experimental condition