Early life history and recruitment dynamics of an amphidromous goby Sicyopterus lagocephalus as inferred from otolith microstructure and microchemistry
Date Issued
2011
Date
2011
Author(s)
Chen, Yu-Hsiang
Abstract
Sicyopterus lagocephalus (Gobiidae: Sicydiinae) is an amphidromous goby and the basic details about its early life history like the duration of pelagic larval stage is still a mystery. In this study, we have used of the otolith microstructure (daily growth increments, metamorphosis check, and increment width) and microchemistry (Sr/Ca ratio) of S. lagocephalus collected from 2 stations in the lower reaches of Hsiukuluan River and from Nanao and Lanyu in eastern Taiwan to understand its early life history, dispersal ,and recruitment dynamics.
The results showed that S. lagocephalus has a whole-year spawning and recruitment period. Recruitment time occurs mostly during the day with the peak at around 15:40. Based on external morphology, the specimens were characterized into five stages: post-larval stages PL1, PL2; juvenile stages J1, J2 and adult stage (A). PL1 stage individuals were mostly found in station 1 (93%) while J1 stage individuals in station 2 (78%). The total length of S. lagocephalus at recruitment to the estuary of Hsiukuluan River were 27.7 mm (range 25.6-29.8 mm, n = 95) with daily age at about 115 days (range 84-162 days, n = 49), and somatic growth rate at about 0.23 mm/d (range 0.2-0.27 mm/d, n = 49). No significant differentiation among seasons were observed (p>0.05). The growth rate was slow at the beginning of larval life; it increased first and then decrease until recruitment to the freshwater. It increased again after the deposition of the metamorphosis check but exhibited asymmetrical growth afterwards. The otolith Sr/Ca ratio in the core was low at the beginning of larval life and it then drastically increase as the fish migrates toward the sea. It will start to decrease as soon as the fish migrates back to the freshwater. Also, there was a geographic decline in the length at recruitment and PLD of S. lagocephalus larvae from south to north in eastern Taiwan. This study has allowed us to improve our knowledge on the early life history and recruitment dynamics of this species, and help managers to implement conservation methods.
Subjects
amphidromous
Sicyopterus lagocephalus
otolith daily growth increment
Sr/Ca ratio
early life history
Type
thesis
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