东海区泗礁沙滩碎波带仔稚鱼种类组成及栖息地利用模式

Species composition and habitat use patterns of fish larvae and juveniles inhabiting the surf zone of a sandy beach at Sijiao Island

为探明泗礁沙滩碎波带仔稚鱼种类组成及其对碎波带的利用模式,于2010年7月至2011年8月每月大潮期间,在泗礁沙滩8个站位点水深0.5~1.5 m处,两人沿海岸平行方向步行拖曳小型拖网（1 m×4 m,网目1 mm）采集仔稚鱼样本。周年采集仔稚鱼1 762尾,隶属于28科46种,其中海洋性鱼类29种,河口性鱼类14种,洄游性鱼类2种,淡水性鱼类1种。体长10~30 mm的仔稚鱼占总渔获量的87.05%;后弯曲期仔鱼和稚鱼分别占总渔获量的24.57%和68.27%。鳀（Engraulis japonicus）为优势种,占总渔获量的55.68%。种类数及单位捕捞努力渔获量（CPUE）春夏季较高而秋冬较低,种类数和CPUE峰值分别出现在2010年8月和2011年5月。站点间的种类数和CPUE变化表明,仔稚鱼偏好栖息于封闭型沙滩碎波带。前10位主要种对碎波带的利用分3种类型：鳀、中国花鲈（Lateolabrax maculatus）、鮻（Liza haematocheila）和棘头梅童鱼（Collichthys lucidus）利用碎波带作为保育场;中华侧带小公鱼（Stolephorus chinensis）、鲻（Mugil cephalus）、细鳞鯻（Terapon jarbua）和弓斑东方鲀（Takifugu ocellatus）连续数月利用碎波带作为暂时栖息地;相模虾虎鱼（Sagamia geneionema）和鲬（Platycephalus indicus）则在单月进入碎波带栖息。因此在进行海滩和港湾开发和利用时,应重视对沙滩破碎带仔稚鱼栖息地的保护。

We investigated the species composition and utilization patterns of fish larvae and juveniles in the sandy beach surf zone at Si Jiao Island.Between July 2010 to August 2011,fish larvae and juveniles were collected monthly using a seine net（1×4 m,1 mm mesh-aperture）.A total of 1762 fish larvae and juveniles,representing 46 species from 29 families were collected from 8 sites along the island.These included 29 marine species,14 estuarine species,2 migration species,and 1 freshwater species.Compared with the surf zone of the south Yangtze estuary and north Hangzhou Bay,which were dominated by migratory and estuarine species,respectively,the sandy beach in Si Jiao island was dominated by marine species,which accounted for 71.68 of the total catch.The standard length of the majority（87.05%） of specimens ranged from 10-30 mm.Postflexion and juvenile individuals accounted for 24.57% and 68.27% of the total catch,respectively.In terms of abundance,Engraulis japonicus, Stolephorus chinensis,Mugil cephalus,Lateolabrax maculatus,Liza haematocheila,Sagamia geneionema, Terapon jarbua,Platycephalus indicus,Collichthys lucidus and Takifugu ocellatus were the 10 most dominant species.The CPUE of fish larvae and juveniles was higher in spring and summer and lower in autumn and winter. The CPUE peaked in May,at which time the majority of the catch（86.7%） consisted of Engraulis japonicus.The highest species richness was observed in August,2010.A Person Correlation analysis（2-tailed） revealed a high significant positive correlation between species richness and water temperature（P0.01） and a significant positive correlation between CPUE and salinity（P0.05）.The spatial variation in CPUE and species richness suggested that fish larvae and juveniles preferred inhabiting protected sandy beaches（St.2,St.5,St.7） rather than open sandy beaches（St.4,St.8）,likely due to the low wave action and calm environment.Stations 5 and 7 contributed the most to species richness and had the highest CPUE,respectively.Based on the monthly changes in standard length of the 10 most dominant species,the habitat use patterns of the 10 species could be divided into 3 types： Engraulis japonicus,Lateolabrax maculatus,Liza haematocheila and Collichthys lucidus increased in size monthly,suggesting they used the sandy beach surf zone as a nursery area.In contrast,there was little change in the standard length of Stolephorus chinensis,Mugil cephalus,Terapon jarbua and Takifugu ocellatus.Last,Sagamia geneionema and Platycephalus indicus were only observed in the surf zone in a single month,suggesting these species use of the zone is restricted to a single or limited development stage.Our data suggest that a number of fish species,including some commercially exploited species,use the sandy beach surf zone as a shelter and/or nursery ground during their early developmental stages（primarily as juveniles and during postflexion）.