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A study was conducted to evaluate zooplankton species composition, abundance, and diversity in both natural and artificial lakes with varying trophic levels and to determine the relationship between zooplankton community structure and lake environmental conditions. This study hypothesized that correlations exist between zooplankton community structures and environmental parameters associated with eutrophication in natural and artificial lakes. Sampling was conducted across 16 distinct freshwater lentic ecosystems in Malaysia, including natural lakes/swamps, reservoirs, constructed lakes/ponds, and old mining lakes, spanning a range of trophic levels from mesotrophic to hypereutrophic conditions. Physicochemical parameters were measured in situ, while water and zooplankton samples were collected for nutrient analyses, as well as for zooplankton identification and enumeration. Throughout this study, a total of 58 zooplankton species, consisting of 36 species of rotifers, 12 species of cladocerans, and 10 species of copepods, were recorded. The highest zooplankton density (365.7 ± 13.7 ind L−1) was recorded in constructed lakes/ponds while the lowest density was recorded in natural shallow lakes/swamps (200.5 ± 25.5 ind L−1). On the other hand, significantly higher (p < 0.05) mean species diversity was observed in natural lakes/swamps (H' = 2.2 ± 0.0); whereas, the lowest diversity was in old mining lakes (H' = 1.5 ± 0.1). The canonical correspondence analysis (CCA) scores indicated that Polyarthra vulgaris and Chydorus ventricosus were the discriminating species in natural shallow lakes/swamps associated with high water transparency. Meanwhile, the small-sized cladocerans (Ceriodaphnia cornuta) and rotifers (Keratella spp., Brachionus spp., and Trichocerca spp.) were the most discriminating species in lakes with high turbidity, nutrients, and chlorophyll a concentrations, which are the main features of reservoirs and constructed lakes/ponds. Low density and diversity in old mining lakes were due to a low species number and the dominance of two species, Lophocharis curvata (38.8%) and Ptygura libera (39.7%). Overall, the high dominance of a specific zooplankton species resulted in lower biodiversity in artificial ecosystems compared to natural ecosystems. This study elucidated that zooplankton community structure in lakes was significantly influenced by the environmental conditions related to the lake trophic status. [ABSTRACT FROM AUTHOR]

The relationship between zooplankton community structure and selected environmental conditions was investigated by simultaneous two-day consecutive sampling in the waters overlying Coral and sand sites off Sibu Island and a Seagrass site off Tinggi Island, Johor, Malaysia. A total of 129 taxa were identified, 60 non-Copepod taxa and 69 Copepod species in all samples. Uni- and multi-variate analyses reveal distinct Coral, sand, Seagrass Copepod assemblages with indicator Copepod species and attributes of their size fractions. Small fraction (100–335 µm) samples contained greatest number of individuals, few rare species and were densest at onshore depths, and the opposite for large fraction (>335 µm) samples but were densest at nighttime and most species rich in the Coral site at night. Higher species diversity at offshore stations is due likely to ecotonal effects of overlapping oceanic and nearshore communities. This study demonstrates the usefulness of uni- and multi-variate analyses in identifying patterns in Zooplankton community structure in representative shallow tropical habitats, and the need for accurate Zooplankton taxonomy, nighttime and daytime and onshore and offshore sampling, and size fractionation of samples. [ABSTRACT FROM AUTHOR]

A new species of Leptostraca, Nebalia terazakii sp. n. is described and figured. The species was sampled from the coral reefs of Pulau Payar Marine Park, Langkawi, Malaysia. There are 32 existing species of Nebalia but Nebalia terazakii sp. n. can be distinguished from the other known species of Nebalia by the following combination of characters: the rostrum is 1.89 times as long as wide and the eyes have no dorsal papilla or lobes. Article 4 of the antennular peduncle has one short thick distal spine. The proximal article of the endopod of maxilla 2 is shorter than the distal, a feature peculiar to Nebalia terazakii sp. n., the exopod of maxilla 2 is longer than article 1 of the endopod, the posterior dorsal borders of the pleonites 6 to 7 are provided with distally sharp denticles, anal plate with prominent lateral shoulder and finally, the terminal seta of the caudal rami is 1.17 times the length of the entire rami. [ABSTRACT FROM AUTHOR]

Inorganic nutrient contents of mucus released by Acropora corals and its utilization by heterotrophic bacteria at several different hour intervals in the coral mucus were investigated at a coral reef in Malaysia. The dissolved inorganic phosphate ( DIP) concentration was 135-fold higher than in the ambient seawater, probably due to inorganic P release from the coral gut cavity. We experimentally confirmed that heterotrophic bacteria rapidly (within 8 h) consumed ca. 80% of the initial concentration of DIP derived from coral mucus. High DIP concentration in coral mucus may enhance heterotrophic bacterial production and associated carbon flow in the microbial loop of reef ecosystems. [ABSTRACT FROM AUTHOR]

Quantitative research on composition, biomass and production rates of zooplankton community is crucial to understand the trophic structure in coral reef pelagic ecosystems. In the present study, micro- (35-100 μm) and net- (>100 μm) metazooplankton were investigated in a fringing coral reef at Tioman Island of Malaysia. Sampling was done during the day and night in August and October 2004, and February and June 2005. The mean biomass of total metazooplankton ( i.e. micro + net) was 3.42 ± 0.64 mg C·m−3, ranging from 2.32 ± 0.75 mg C·m−3 in October to 3.26 ± 1.77 mg C·m−3 in August. The net-zooplankton biomass exhibited a nocturnal increase from daytime at 131-264% due to the addition of both pelagic and reef-associated zooplankton into the water column. The estimated daily production rates of the total metazooplankton community were on average 1.80 ± 0.57 mg C·m−3·day−1, but this increased to 2.51 ± 1.06 mg C·m−3·day−1 if house production of larvaceans was taken into account. Of the total production rate, the secondary and tertiary production rates were 2.20 ± 1.03 and 0.30 ± 0.06 mg C·m−3·day−1, respectively. We estimated the food requirements of zooplankton in order to examine the trophic structure of the pelagic ecosystem. The secondary production may not be satisfied by phytoplankton alone in the study area and the shortfall may be supplied by other organic sources such as detritus. [ABSTRACT FROM AUTHOR]

The article presents a study on the effects of temperature on the success of egg development time and hatching of three acartia species located in the Strait of Malacca, Malaysia, namely Acartia spinicauda, A. erythraea and A. pacifica. According to the study, the values of biological zero for Acartia were significantly correlated with environmental temperatures which suggests that differences in temperature adaptation of development rates of eggs can be described from a single parameter of the temperature response. Development times and hatching success were found at 10, 14, 18, 22, 17, and 31 degrees Celsius.

Biologically diverse coral-reef ecosystems are both directly and indirectly susceptible to changes in the spectral ultraviolet radiation (UVR) distribution. The purpose of this study was to (1) measure the variability of UVR and photosynthetically active radiation (PAR) penetration in the water above coral reefs around the Malaysian peninsula, (2) measure the variability and distribution of UVR-specific biogeochemical factors, and (3) determine the impact of biogeochemical variability as it affects the UVR:PAR ratio. Downwelling UVR and PAR irradiance and bio-optically derived biogeochemical factors were measured at 14 coral survey stations around the Malaysian peninsula from August 10–29, 2007. The West Coast was characterized by relatively shallow mean 10% UV-B (320 nm) penetration (1.68 ± 1.12 m), high chlorophyll (3.00 ± 4.72 μg l−1), high chromophoric dissolved organic matter (CDOM; 6.61 ± 3.31 ppb), high particulate organic carbon (POC; 190.65 ± 97.99 mg m−3), and low dissolved organic carbon (DOC; 1.34 ± 0.65 mg m−3). By contrast, the East Coast was characterized by relatively deep mean 10% UV-B penetration (5.03 ± 2.19 m), low chlorophyll (0.34 ± 0.22 μg l−1), low CDOM (1.45 ± 0.44 ppb), low POC (103.21 ± 37.93 mg m−3), and relatively high DOC (1.91 ± 1.03 mg m−3). The UVR:PAR ratio was relatively higher on the East Coast relative to the West Coast, suggesting variable concentrations of UVR-specific absorbing components. At all sites, UVR attenuation coefficients showed significant correlations with CDOM, but were spatially dependent with regard to chlorophyll a, POC, and DOC. The results suggest that bio-optically significant CDOM and DOC factors are uncoupled in coral-reef communities of Malaysia. Furthermore, the results support prior studies that show chromophorically active concentrations of DOM and POC are significantly altering the amount of UVR penetration above coral reefs and may be notable factors in regulating intricate biogeochemical cycles around benthic coral communities in Malaysia. [ABSTRACT FROM AUTHOR]

Four new species of the genus Apsiphortica Okada, 1971 are described: A. longiciliata Cao and Chen, A. melanogaster Chen, and A. xui Chen, spp. nov. from southwest China, and A. multiclavata Chen and Toda, sp. nov. from Sabah in Malaysia. Supplementary descriptions are provided for two known species, A. holubi Máca, 2003 and A. lini (Okada, 1971), after examination of the holotype specimens. A key to all the species of the genus Apsiphortica is provided. [ABSTRACT FROM AUTHOR]

Eight species of the Amiota sinuata species group are reported from eastern Malaysia, including six new species, A. bispinula, A. cerata, A. curvibacula, A. lambirensis, A. parviserrata and A. quadrifoliolata spp. nov. A key to Asian species of the group is provided. [ABSTRACT FROM AUTHOR]

A study on seasonal phytoplankton abundance and composition in a mangrove estuary, Matang Mangrove Forest Reserve (MMFR), Malaysia, was carried out to determine the phytoplankton structure in this ecosystem, and to identify potential indicators of environmental changes. Phytoplankton samples were collected bimonthly from June 2010 to April 2011, to cover both dry (June to October) and wet (November to April) seasons, at four selected sampling sites along the river. Diatoms showed the highest number of species (50 species) from a total of 85 phytoplankton species from 76 genera. Diatoms contributed more than 90% of the total phytoplankton abundance during the dry season (southwest monsoon) and less than 70% during the wet season (northeast monsoon) as dinoflagellates became more abundant during the rainy season. Two diatoms were recorded as dominant species throughout the sampling period; Cyclotella sp. and Skeletonema costatum. Cyclotella sp. formed the most abundant species (62% of total phytoplankton) during the dry period characterized by low nutrients and relatively low turbidity. Skeletonema costatum contributed 93% of the total phytoplankton in October, which marked the end of the dry season and the beginning of the wet season, characterized by strong winds and high waves leading to the upwelling of the water column. Massive blooms of Skeletonema costatum occurred during the upwelling when total nitrogen (TN) and total phosphorus (TP) concentrations were highest (p < 0.05) throughout the year. The abundance of diatom species during the wet season was more evenly distributed, with most diatom species contributing less than 12% of the total phytoplankton. Autotrophic producers such as diatoms were limited by high turbidity during the northeast monsoon when the rainfall was high. During the wet season, Cyclotella and Skeletonema costatum only contributed 9% and 5% of the total phytoplankton, respectively, as dinoflagellates had more competitive advantage in turbid waters. This study illustrates that some diatom species such as Cyclotella sp. and Skeletonema costatum could be used as indicators of the environmental changes in marine waters. [ABSTRACT FROM AUTHOR]