| Sepiella maindroni used to be one of the four major traditional marine products in China.It became nearly extinct in the 1990 s.Large-scale proliferation and releasing work has been carried out in recent years,but it still cannot meet needs for resource recovery.The life cycle of S.maindroni is short.It has the feature of breeding migration.Its resources completely depend on recruit stock.Therefore,to protect and restore its spawning grounds and even to construct favorable spawning habitats according to its spawning preferences have become a new direction for S.maindroni resource restoration.This study takes Zhongjieshan Islands Special Marine Protected Area as the research area.Biological investigation on its spawning grounds,preference of its oviposition selection and preliminary construction of its spawning habitats are respectively carried out.The study means to provide assistance for the related researches of S.maindroni resources restoration and to provide references for the resource restoration of other Cephalopods.1.The species composition,seasonal changes and ecological niches were analyzed based on the trawl survey data of the Zhongjieshan Islands.All 115 species have been identified in four seasons,with rich species diversity,and 15 dominant species are recognized.The seasonal change index was spring > winter > summer > autumn,and the migratory change index was winter > autumn > summer > spring.The seasonal change range is large.The maximum value of spatio-temporal niche width is Oratosquilla oratoria,the minimum value is small Larimichthys polyactis.The overlapped value of spatio-temporal niche between Charybdis japonica and Raja porosa is the maximum,and the minimum overlapped value is between L.polyactis and Coilia nasus.All 50.55% of the species have significant overlap,among them like Palaemon gravieri,Collichthys lucidu,O.oratoria,Harpodon nehereus,Portunus trituberculatus and Solenocera crassicornis.They all have a significant spatiotemporal niche overlapping with S.maindroni.There is an interspecies competition when food resources are insufficient.2.Indoor experiments are conducted on the mating selection,tendency of grouping,and spouse selecting,based on the hypothesis of behavior and region distribution of S.maindroni during the spawning period.Seven types of behaviors have been observed during the mating selection: courtship behavior,demonstration behavior,aggressive behavior,escaping behavior,escorting behavior,mating behavior,and spawning behavior.The results show that the competition for mating rights is fierce or even deadly.The results of three groups of grouping tendency test show that the proportion of instant clustering number reaching three or more tails was 87.5%,100% and 62.5% respectively,which indicates that squid has certain clustering preference.The results of heterosexual selection test show that both females and males in the enclosed area could attract other heterosexuals to some extent,but females attract males more.3.According to the results of gorgonian coral ecological habitat survey,three areas with large different distribution of gorgonian coral are selected in the Zhongjieshan Islands Special Marine Protected Area,and the preliminary ecological habitats are constructed by putting in a combination frame composed of three different types of attachments.The underwater observation results show that it has a significant effect of fish collection and attracted the attachment of oosperm of Loligo sp.,but there is a little different between the outcome and the expectation.This paper proposes corresponding optimizating measures for several problems that may cause the differences.In addition,we have optimized the design of gorgonian-like spawning attachment for S.maindroni,and put forward a feasible deployment plan in order to provide help for the subsequent construction of S.maindroni spawning habitats. |
PDF Full Text Request