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Abstract |
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Fish were collected by pole fishing and ground seine nets from Shimizu harbor in Shizuoka prefecture,Japan,
2004〜2006:113fish species were identified.Of these fish, 24species (8orders 20families)lived permanently in the
harbor basin year-round.The remaining 89species (13orders 54families)were ones which advanced into the harbor
basin depending on adaptability and environment,including water quality and available food organisms.Therefore,
the fish community structure of the harbor basin was regarded as dynamically changing according to seasonal
movement of the various fish species.
The scorpion fish (Sebastiscus marmoratus) was selected for close study. The adult has a narrow range of
movement and the multiple groups found in Suruga Bay (next to Shimizu harbor) were analyzed for genetic
variability and population structure. Each group displayed high genetic variability, there was also a high level of
similarity between groups.These results suggest that the effective size of the Shimizu harbor scorpion fish group is
big enough to also cover Suruga Bay,and it is maintained by the various groups.Then,it was presumed that the fish
larvae in the floating stage were helping the gene flow.
As a fish supply-mechanism for the Shimizu harbor, it was considered that the formation around the harbor
entrance of an estuary front,with a high distribution density of food organisms, a certain level of entrainment and
the tide motion are all important factors.It also appears that environmental conditions around the harbor entrance
are directly affected by the dynamic movement of the flow of river water into the harbor. |
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