Diurnal and lunar patterns of larval recruitment of Brachyura into a mangrove estuary system in Ranong Province, Thailand |
| |
Authors: | S M Moser D J Macintosh |
| |
Institution: | (1) Department of Ecology and Genetics, Building 540, University of Aarhus, 8000 Aarhus C, Denmark e-mail: Sean.Moser@biology.au.dk Tel.: +45-89423302; Fax: +45-89423350, DK |
| |
Abstract: | The present study followed the temporal recruitment pattern of brachyuran larvae in a mangrove tidal creek on the Andaman
Sea coast of Ranong Province, Thailand, based on the assumption that the processes governing recruitment are important for
the overall population dynamics of mangrove brachyuran crabs. Plankton net samples were taken on five occasions: on two new
moon spring tides, one waxing moon neap tide, one full moon spring tide and one waning moon neap tide during October and November
1997. In addition collectors for larval crab megalopae were employed every 3 days through one dry season and one wet season
(March–October 1998). Both the plankton net samples and collector samples revealed four major brachyuran groups in three families:
Ocypodidae, Grapsidae and Portunidae. The grapsid group was further separated into two morphotypes which were identified as
Metaplax and sesarmid species. Identified group mean numbers per cubic metre were ocypodids 3.0, sesarmids 0.8 and Metaplax 0.5, while portunid megalopae were very scarce (≪0.1 m−3). Further analysis of plankton net samples showed that when considering the parameters date, depth, current direction and
the diel cycle, Metaplax and ocypodids distribute differently in the tidal and lunar cycle. Metaplax recruitment dominates on flood tides and on bottom layers, followed by middle and surface layers. Conversely, ocypodid abundance
varied significantly with date only. Notably recruitment was not dependent on the diel cycle for either group. The collector
samples of megalopae showed that recruitment of ocypodids, Metaplax and sesarmids occurred on full and new moon spring tides, while portunid megalopae preferred to settle on full moon spring
tides. Since tidal currents were related to the lunar cycle megalopa groups are also cross-correlated with tidal amplitude,
except for the portunid group. It is concluded that megalopae recruit in a similar manner to what has been found in other
regions of the world, except that the abundance of ocypodids and Metaplax is not influenced by the diel cycle.
Received: 14 February 2000 / Accepted: 24 November 2000 |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|