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Vol. 51 No. 6, 2012
Population Structure and Reproduction of the Mysid Shrimp Acanthomysis thailandica (Crustacea: Mysidae) in
a Tropical Mangrove Estuary, Malaysia
Tueanta
Ramarn1,3, Ving-Ching Chong1,2,*, and Yukio
Hanamura4
1Institute
of Biological Sciences, University of Malaya, Kuala Lumpur 50603,
Malaysia
2Institute of Ocean and Earth Science,University of
Malaya, Kuala Lumpur 50603, Malaysia
3Department of Biology, Faculty of Science, Thaksin
University, Phattalung Campus, Phattalung 93110, Thailand
4Japan International Research Center for Agricultural
Sciences, Owashi 1-1, Tsukuba 350-8686, Japan
Tueanta Ramarn, Ving-Ching Chong, and Yukio Hanamura
(2012) The mysid
shrimp Acanthomysis thailandica Murano, 1988 in the
Matang mangrove estuary showed large spatial and temporal variations in
population density. Large numbers occurred on the mudflat where
the mean salinity was 25 ppt, but rapidly declined towards the upper
estuary (14 km upstream) where the salinity fell to 15 ppt.
Mysids were present year-round and exhibited marked monthly variations
in abundance, with modal peaks in May, Sept., and Dec. 2009 and Apr.
2010 in the mudflat area. All developmental stages were observed,
except juveniles which were absent from the middle to upper
estuary. Females predominated over males and matured at a smaller
size. Juveniles and empty (= post-spawning) females comprised the
largest groups (at about 17% for each stage) of the population on the
mudflat suggesting that the mudflat serves as the main spawning and
nursery ground. Brooding females occurred together with juveniles
in all monthly samples, indicating that reproduction was year
round. Brood size was independent of female body length, and
ranged 5-25 embryos per brood. Mean lengths of eggs (0.26 ± 0.03
mm), and eyeless (0.58 ± 0.06 mm) and eyed larvae (0.73 ± 0.10 mm) were
also independent of total length.
Key words: Reproductive biology, Spatial and
temporal abundance, Developmental stages, Mudflat area, Crustacea.
*Correspondence: Tel: 603-79674220. Fax:
603-79674178. Present address: National Research Institute of
Fisheries Science, Fisheries Research Agency, Fuku-ura-2-12-4,
Kanazawa-ku, Yokohama 236-8648, Japan. E-mail:chong@um.edu.my
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