Md. Masum Billah

Status of some fishery resources in a tropical mangrove estuary of Sarawak, Malaysia

Abstract This study was carried out to assess the fishery resources of the Sibuti River estuary, Sarawak, Malaysia. Data were collected from the study area for a period of one year in different seasons. The estuary is relatively species-rich and a total of 4675 individuals of 32 families from 60 species of fish (55), crab (four) and shrimp (one) were collected. Coilia dussumieri was the dominant species (22.63%) followed by Nemapteryx caelata (11.85%), Otolithes ruber (7.85%) and Ilisha elongata (5.80%). Marked seasonal variations were found among most of the hydrobiological factors; however, seasonal variations were not significant for the diversity indices such as Shannon–Wiener, Margalef and Evenness. The number of fish taxa caught in different mesh size gill nets was 1 inch (42 species) > 2 inch (36 species) > 4 inch (25 species), suggesting that smaller mesh nets are more suitable for assessing the diversity of fishery resources. SIMPER analysis showed that Coilia dussumieri was the most abundant species in the dry (10.3%) and intermediate (8.1%) seasons, whereas N. caelata was most abundant in the wet season (7.1%). Significant differences (ANOSIM and nMDS) were observed in the species community structure between dry–intermediate and dry–wet seasons; however, species compositions were not significantly different between intermediate and wet seasons. Canonical correspondence analysis (CCA) showed that most of the species assemblages were positively correlated with turbidity and chlorophyll a, followed by phosphate, nitrate and zooplankton density. The findings suggest that the Sibuti mangrove estuary is productive in terms of diversified fishery resources, which are influenced by the hydrobiological factors.

Seasonal Variation in the Occurrence and Abundance of Mangrove Macroalgae in a Malaysian Estuary

Abstract Mangrove macroalgae produce substantial proportion of biomass, which contributes to the coastal ecosystems. Relatively less is known for the seasonal variation in the occurrence and biomass of mangrove associated macroalgae. Consequently, mangrove macroalgae epiphytic on the pneumatophores of Avicennia marina (Forsk.) Vierh., were sampled from the Miri estuary of Sarawak during the four seasons of Malaysia namely southwest monsoon, northeast monsoon, and two inter-monsoons to elucidate seasonal variation in the occurrence and biomass production of macroalgae. Over the sample period, 11 species of mangrove macroalgae were identified from 6 genera. Six of these species such as Caloglossa leprieurii (Montagne) J.Agardh, C. adhaerens R.J.King & Puttock, C. stipitata E.Post, C. ogasawaraensis Okamura, Bostrychia kelanensis Grunow and Dictyota sp. were found to be common in each sample time. Considering four seasonal samples, maximum frequency of occurrence was observed for C. ogasawaraensis (66 ± 10%) and maximum biomass was observed for B. kelanensis (248 ± 95 g m-2). Marked seasonal variations were observed in the frequencies of occurrence and the biomass for the most of the dominant macroalgal species. To the best of our knowledge this is the first time to report the seasonal pattern data for occurrence and abundance of macroalgae from the mangrove systems of Malaysia.

Distribution of Trace Metals in Channel Sediment: a Case Study in South Atlantic Coast of Spain

Recently, Sancti Petri channel on the southwestern (SW) part of Iberian Peninsula has been experiencing urban, industrial, and vehicular expansion. Until recently, there have been only few published reports documenting the pattern of metal accumulation in this estuarine sediment. In the present study, trace metals such as Cu, Zn, Ni, Mn, Pb, Co, Cd, As, and Hg concentrations were analyzed from 69 sediment samples collected from 23 sampling sites of the Santi Petri channel. The magnitude of trace metal accumulation found as the following trend: Mn > Zn > Cu > Pb > Ni > Co > As > Cd > Hg. Spatial distribution pattern demonstrated overall decreasing trend of trace metal from Cadiz Bay mouth to the open ocean mouth, clearly correlative to the presence of anthropogenic inputs. Results of the principle component analysis (PCA) revealed that sediment metal chemistry of Sancti Petri channel is mainly regulated by the concentrations of Pb, Cu, Zn, and Ni; possible sources of those were from vehicular-related emissions. Pollution load index (PLI) and geo-accumulation index (Igeo) indicated overall low values. The study will stimulate improvement of our understanding regarding the pattern of accumulation of metals in the coastal sediments, and the recorded values of metals in the present study can be used as suitable reference for future studies.

Saltmarsh and seagrass beds on the south-eastern coast of Bangladesh: vegetation characteristics and adjacent fisheries diversity

AbstractSaltmarsh and seagrass communities are coastal macrophytes. These communities perform a number of important ecological functions, one of which is to support substantial fishery resources either as a nursery ground or a refuge from predators. The Bangladesh coast houses saltmarsh and seagrass resources but there has been sparse information on the diversity of fisheries adjacent to these plant communities. Consequently, this study was carried out to obtain information on the shoot density and biomass of the dominant saltmarsh (Porteresia coarctata) and seagrass (Halophila beccarii) species together with the diversity of fisheries adjacent to saltmarsh and seagrass beds on the south eastern coast of Bangladesh. The below-ground biomass of P. coarctata was found to be significantly higher than the above-ground biomass, presumably so as to survive under harsh environmental conditions, for example strong wave exposure. The standing crops and shoot density of the seagrass H. beccarii showed a similar pat...

Population biology of the pool barb Puntius sophore (Hamilton 1822) (Cyprinidae) in the Padma River, Bangladesh

The cyprinid pool barb Puntius sophore (Hamilton 1822) is widely distributed in freshwaters of Southern Asia. We determined some basic population biology parameters of P. sophore including sex ratio, length-frequency distributions (LFDs), length-weight relationships (LWRs), condition factors, relative weight and fecundity. Samples were collected monthly during July 2010 to June 2011 from the Padma River, Bangladesh. The overall fish sex ratio significantly differed from the anticipated value of 1:1 (p < 0.001) in favour of female specimens (1: 1.31). Females were significantly larger and heavier than males (p < 0.001). The LWRs showed isometric growth in both sexes; however, with clear monthly variation. Fultons condition factor was found to be significantly correlated with the total length (TL) and body weight (BW) and the most suitable among the studied condition factors for interpreting population well-being. Total fecundity varied from 1488 to 18708 (5682 ± 3703), while the relative fecundity...

Decay of Rhizophora apiculata (Blume) and Xylocarpus granatum (Koenig) detrital sources in the Sarawak Mangrove, Malaysia

Decaying mangrove detritus plays a significant role in nutrient cycling and fueling in both the forests and aquatic habitats where the detritus stems from estuarine and coastal food webs. Detrital decay rates partly depend on the type of detritus, but most studies have thus far focused on leaf litter decay and decomposition, whereas other detrital sources (except for roots) have largely been ignored. We compare the decay rates of Rhizophora apiculata and Xylocarpus granatum non-leafy detritus (flowers, propagules, stipules, and twigs) with mangrove leaf litter in field studies, using litter bags during the dry and the wet seasons in the tropical mangrove forest of Sibuti, Sarawak, Malaysia. We observed higher microbial decay rates of stipules, flowers, propagules, and twigs for both the R. apiculata and X. granatumduring the wet months. By contrast, leaf decay rates were higher during the dry months. Decay rates depended on the lignin content of the detrital sources of both species, both during dry and wet months. Accordingly, the half-life (T0.5) and 95% lifespan (T0.95) of non-leaf materials (flowers, propagules, stipules and twigs) for both species were remarkably longer than those of leaf litter. Slowly decaying non-leafy detritus may play a significant role in nutrient and carbon cycling over longer time, when leaf litter is either being decomposing rapidly and/or being washed away by tidal flush and river runoff. Hence, non-leafy (flowers, propagules, stipules and twigs) detritus should be taken into account when budgeting organic matter turnover in mangroves.