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

Assessment parameters for coal-fired generation plant site selection

In order to meet future demand for electricity, Tenaga Nasional Berhad (TNB) is committedto the long-term strategic planning in locating suitable sites for future development of power stations.Site selection is an important process in the early planning stage of any power plant development asit will have significant implications on the capital investment, operational as well as the environmentand socio-economic costs of the power plant.The aim of this presentation is to briefly describe the ten (10) main assessment parametershaving the most profound effects on the selection of potential coal-fired generation plant sites.These assessment parameters were derived based on a survey of approximately 40 experts, comprisingfrom various specialists such as engineers from TNB, senior officers from Department Of EnvironmentMalaysia (DOE), scientist from University Malaya (UM) and a number of other independentconsultants

Effects of habitat modification in mangroves on the structure of mollusc and crab assemblages

The abundance and species richness of mollusc and crab assemblages were examined in a subtropical mangrove forest in Moreton Bay, Queensland, Australia, which has been disturbed and damaged by the construction of a wooden boardwalk and a path. Sections of the forest immediately adjacent to the boardwalk and path were compared with reference areas to determine whether changes to the small-scale structural complexity within the forest affected the benthic fauna. The disturbed area was characterised by having 65-80% fewer pneumatophores, significantly fewer species and individuals of molluscs, but significantly more species and individuals of crabs than the reference areas. The abundance of mangrove pneumatophores and the attached epiphytic algae were manipulated at two sites to determine whether observed differences in these features could account for the differences in the assemblage of molluscs in the disturbed area of the forest compared with reference areas. Five experimental treatments were used: undisturbed controls, pneumatophore removals (abundance reduced by ca. 65%), epiphytic algal removals (algae removed from ca. 65% of pneumatophores), pneumatophore disturbance controls and algal disturbance controls. The experimental reduction of the abundance of mangrove pneumatophores and the associated epiphytic algae led to significant declines (by as much as 83%) in the number of molluscs utilising the substratum in the modified plots. There was no significant difference in the abundance of molluscs in the pneumatophore and algal removal plots suggesting any effect was primarily related to removal of the epiphytic algae from the surface of the pneumatophores. The responses by the biota to the changes in the physical environment demonstrate that even relatively small-scale modifications to the physical structure of subtropical mangrove forests can lead to significant effects on the diversity and abundance of macrobenthic organisms in these habitats. Such modifications have the potential to cause cascading effects at higher trophic levels with a deterioration in the value of these habitats as nursery and feeding grounds. Future efforts at conservation of these estuarine environments must focus on the prevention or reduction of modifications to the physical structure and integrity of the system, rather than just on the prevention of loss of entire patches of habitat. (C) 2000 Elsevier Science B.V. All rights reserved

Meiofauna of a mangrove shore on the west coast of Peninsular Malaysia

The meiofauna (size range 53 to 1000 !-lm) of the mangrove shore sediments in Malaysia consist predominantly of free-living nematodes, harpacticoid copepods, oligochaetes and kinorhynchs, increasing in abundance with decreasing tidal height where water stress is minimal. The highest density of 1l09±27 individuals per 10 cm-2 occurred in the Avicennia station of the lower shore, while a density of 583±186 individuals per 10 cm-2 was obtained at the mid-tide level Rhizophora station, and the high shore Bruguiera station had the lowest density of 407±188 individuals per 10 cm-2• The meiofaunal biomass was 6.16 mg, 7.54 mg and 0.96 mg w.w. per 10 cm-2 in the Avicennia, Rhizophora and Bruguiera stations respectively. The reduction in meiofauna numbers and biomass on the high shore is attributed to habitat instability arising from intense salinity fluctuations, infrequent tidal cover and water stress. The fauna was unevenly constituted with the nematodes forming 80 to 93% of the meiofauna community, and the harpacticoids being the next abundant group. Most meiofauna live in the upper 2 cm layer of the sediment. It may be concluded that the greatest abundance of meiofauna occurred in the lower shoreAvicennia forest and the lowest abundance in the high shore Bruguiera forest

Food and Feeding Habits of the White Prawn Penaeus merguiensis

Stomach-content analyses revealed that the white prawn Penaeus merguiensis de Man, in the Angsd Bank-Klang Strait waters (Straits of Malacca), feed on a variety of food - depending on the locality and availability of food items. In the nursery ground, newly-arrived pelagic postlarvae are carnivores, feeding largely on copepods. Epibenthic postlarvae and juveniles are carnivorous detriti-vores, consuming mainly organic detritus; they also prey on small animals like foraminiferans, copepods, larval bivalves and brachyuran larvae. In the maturation ground, subadults are detritivorous carnivores, feeding mainly on large crustaceans, like species of Acetes and mysids; in lesser amounts, on organic detritus. In the spawning ground, adults are detritivore-cdrnivores consuming equal amounts organic detritus and a variety of large crustaceans, polychaetes, molluscs and fishes. However, there are indications that the prawn prefer animal food if available. Organic detrltus is considered a food supplement; its utilization as a food source becomes important to the maturing prawn when it assumes a benthic existence