Mangrove Conservation - A Fisheye View

An inaugural lecture delivered at the University of Malaya on Thursday, July 8, 2010

Influence of habitat heterogeneity on the assemblages and shell use of hermit crabs (Anomura: Diogenidae)

Background Two contrasting intertidal habitats on the western Sabah coast (Malaysia), one is a rocky-sandy-mud flat at Sepangar (N6°02′18.57″; E116°06′40.07″) and the other is a mangrove foreshore at Sulaman (N6°15′33.00″; E116°18′49.80″), are characterized by substrate zonation and homogeneous substrate (mud), respectively. Hermit crabs are one of the most conspicuous benthic macrofauna at both sites. The study examined the influence of habitat heterogeneity on the assemblages and shell use pattern of hermit crabs. Results The heterogeneous intertidal flat at Sepangar (five species) supported a higher diversity and abundance of hermit crabs compared to Sulaman mangrove foreshore (two species). Hermit crabs at Sepangar used a greater variety of shells (30 species) compared to those at Sulaman (two species). Zonation of hermit crab species occurred at Sepangar where Diogenes klaasi dominated at the high-tide mark and two Clibanarius species (C. striolatus and C. merguiensis) dominated at the low-tide mark. Considerable overlap in habitat use (mid- and lower shore) occurred between D. tumidus and the two Clibanarius species which appeared to influence shell use pattern. Conclusions This study supports the work of others showing that structurally complex habitats will allow habitat partition among species thus explaining the greater diversity and abundance of hermit crabs. Such a heterogeneous habitat provides a wider choice of shells for the hermit crabs, minimizing interspecific competition for the available shell resources

The use of otolith morphometrics in determining the size and species identification of eight mullets (Mugiliformes: Mugilidae) from Malaysia

Sagittal otolith morphometric measurements from Malaysian Mugilidae species were selected to investigate their possible role in species identification, due to the Mugilidae species’ morphological similarities, and age determination. Fish standard length (cm), otolith length (μm), width (μm) and mass (g) measurements were taken from eight species: Chelon macrolepis, C. melinopterus, C. subviridis, Ellochelon vaigiensis, Moolgarda cunnesius, M. seheli, Mugil cephalus and Valamugil engeli. Otolith aspect ratio, OAS (otolith length divided by width), was calculated and compared between species. The four homogenous groups based on their OAS were C. melinopterus (mean=1.65) and V. engeli (1.66) and M. cunnesius (1.89) and E. vaigiensis (1.89); M. seheli (2.08), C. macrolepis (2.14) and M. cephalus (2.17); and the latter two with C. subviridis (2.43). The relationships between fish standard length and otolith length/mass showed positive correlations for both, with otolith length providing the stronger correlation (rs = 0.897, P < 0.001) than otolith mass (rs = 0.795, P < 0.001). It is concluded that the more morphologically similar species have similar otolith aspect ratios, related to head shape; however, otolith shape is also affected by a variety of other environmental factors that have to be taken account of

Coastal biodiversity of Langkawi Island: Threats and conservation issues

国際ワークショップ：International Workshop on Tropical Island Biodiversity: Across Land and Sea, 日時：2007年9月25日～29日, 場所：シンガポール国立大学（シンガポール）およびティオマン島（マレーシア）, 共催：琉球大学21世紀COEプログラム, シンガポール国立大学生物科学

Notes on the snake eel neenchelys buitendijki(Ophichthidae: Myrophinae), a new record for Malaysia

Neenchelys buitendijkiWeber and de Beaufort, 1916 from Malaysia is reported for the first time. Five specimens collected from Matang, Peninsular Malaysia, represent the third record in the Indo-western Pacific region. A detailed description is provided to document the species into the fish fauna of Malaysia

Response of marine copepods to a changing tropical environment: winners, losers and implications

Background. Climate change concurrent with anthropogenic disturbances can initiate serial changes that reverberate up the food chain with repercussions for fisheries. To date, there is no information available concerning the combined effects of global warming and human impacts on tropical marine food webs. While temperate copepods respond differently to warming and environmental stressors, the extent to which tropical copepods can adapt to rising temperature of already warm waters remains unknown. We hypothesize that sea warming and other anthropogenic disturbances over the long term will have the greatest impact on the copepod community in nearshore waters where their effects are accentuated, and therefore vulnerable and resilient species could be identified. Methods. Zooplankton samples were collected during two time periods (1985–86 and 2014–15) interposed by marked anthropogenic disturbances, and at the same five stations located progressively from inshore to offshore in Klang Strait, Malaysia, following the asymmetrical before-after-control-impact (BACI) design. Copepods were identified to species, and results were interpreted by univariate (ANOVA) and multivariate (PERMANOVA, PCO) analyses of the computed species abundance and diversity measures. Results. Copepod total abundance was not significantly different among stations but higher after disturbance than before disturbance. However, changes in the abundance of particular species and the community structure between time periods were dramatic. Coastal large-bodied calanoid species (e.g., Acartia spinicauda, Calanopia thompsoni, Pseudodiaptomus bowmani and Tortanus forcipatus) were the most vulnerable group to disturbance. This however favored the opportunistic species (e.g., Oithona simplex, O. attenuata, Hemicyclops sp., Pseudomacrochiron sp. and Microsetella norvegica). Small-bodied copepods (e.g., Paracalanus sp., Parvocalanus crassirostris and Euterpina acutifrons) were unaffected. Centropages tenuiremis was likely an introduced species. There was no significant loss in species richness of copepods despite the dramatic changes in community structure. Discussion. Sea warming and other human-induced effects such as eutrophication, acidification and coastal habitat degradation are likely the main factors that have altered copepod community structure. The large-bodied estuarine and coastal calanoid copepods are surmised to be vulnerable to eutrophication and hypoxia, while both resilient and opportunistic species are largely unaffected by, or adaptable to, degraded coastal environments and observed sea surface temperature (SST) rise. It is forecasted that SST rise with unmitigated anthropogenic impacts will further reduce large-bodied copepod species the favoured food for fish larvae with dire consequences for coastal fish production

Description and ontogeny of young Stolephorus baganensis and Thryssa kammalensis, two Engraulididae from peninsular Malaysia

The morphology of the digestive system was usefull to distinguish the larvae of #Stolephorus baganensis and #Thryssa kammalensis before the full development of their dorsal and anal fins. The relative positions of these fins, the length of the anal fin, and body depth, were good criteria for identifying individuals greater than 10.0 mm Ls. For both species, the relative growth of the ten morphometric characters studied was best explained by linear piecewise regressions indicating inflection in allometry at specific standard lengths. Most of these sudden changes in growth rate occurred between 6.9 and 10.0 mm Ls for #S. baganensis and between 5.8 to 8.9 mm Ls for #T. kammalensis. Double-centred principal component analysis (PCA) confirmed important changes in the external morphology of both species during this transition period. Prior to this period, the main parameters characterizing the global morphological changes of both species were the length and position of dorsal and anal fins whereas they were body depth and eye diameter (only in #S. baganensis) for larger specimens. Complete development of scales did not appear as a suitable criterion to define the end of the larval period, which, instead, was set at the size at which larvae presented an adult-like pigmentation (respectively 35.0 mm Ls and 55.0 mm Ls in #S. baganensis and #T. kammalensis$). (Résumé d'auteur

Phylogenetic relationships of selected genera of Lutjanidae inferred from mitochondrial regions, with a note on the taxonomic status of Pinjalo pinjalo

Phylogenetic relationships of 43 species in 11 genera, representing four subfamilies of the family Lutjanidae and two genera of the family Caesionidae, were inferred using mitochondrial DNA (mtDNA) cytochrome c oxidase subunit I (COI). Further assessment using the mtDNA control region (CR) was carried out to infer the relationship between the Indian and western Pacific types of Lutjanus russellii collected from the coast of Peninsular Malaysia. A total of 11 and 12 species were sequenced for COI and CR genes, respectively. Clade formation reflects, to some extent, the species groupings based on morphological characteristics and their biogeography. The close phylogenetic relationship between Pinjalo pinjalo and the Lutjanus red snappers (Lutjanus malabaricus and Lutjanus sebae) warrants a taxonomic revision of the former as the two genera are currently separated based on non-exclusive morphological characters. A sequence divergence of 4.2% between the Indian and western Pacific types of L. russellii as well as the morphological and biogeographical differences may suggest two separate species.