Assessment of litterfall production is essential to ascertain the status of nutrient cycling and forest health. Sarawak, Malaysia, is endowed with numerous pristine and estuarine mangroves; however, research on primary productivity of these forests is scanty. Therefore, litterfall production in a pristine Sibuti mangrove of Sarawak was estimated using litter traps for one year (January-December 2013), and forest structure was studied through tree census. The forest was dominated by Rhizophora apiculata (relative density [RD] was 77.11%), followed by Xylocarpus granatum (RD was 16.92%) and other species (RD was only 5.97%). The annual dry weight of litterfalls was estimated to be 1640.82 g m −2 , of which R. apiculata contributed 92.94%, followed by X. granatum (4.01%) and other species (3.05%). Leaves were the most abundant (57.21%) contributory component of litters, followed by propagules (11.89%), flowers (10.85%), twigs (8.56%), and stipules (8.45%). No significant correlations were found for total litterfall and its major components with climatic variables and forest structure. Total litterfall of R. apiculata and X. granatum did not show any seasonal variations. However, leaf litter of R. apiculata showed a significant seasonal variation between intermediate (January-April) and wet (September-December) seasons. The litterfall production of Sibuti mangrove forest is higher in comparison to other tropical mangroves of the world. The higher productivity of the forest could be due to nutrient availability, pristine nature, and stand maturity of the forest rather than climatic influences. The findings of the study suggest that litterfall production of the pristine Sibuti mangrove is not influenced by the variability of climatic factors.Maisto medžiagų apykaitos miške ir jo būklės įvertinimui labai svarbūs nuokritų susidarymo tyrimai. Daug žmogaus veiklos nepaliestų ir nepakankamai ištirtų estuarinių mangrovių yra Malaizijoje, Saravako valstijoje. Saravake esančioje Sibuti mangrovėje nuo 2013 m. sausio iki gruodžio miško nuokritų susidarymas buvo tiriamas nuokritų gaudyklėmis. Įvertinta medžių rūšinė sudėtis: dominavo Rhizophora apiculata -77,11% ir Xylocarpus granatum -16,92%, kitų rūšių medžiai sudarė 5,97%. Sausas nuokritų svoris per metus buvo 1640,82 g/m 2 , iš jų R. apiculata -92,94%; X. granatum -4,01%, kitų rūšių -3,05%. 57,21% nuokritų sudarė lapai, 11,89% -vegetatyvinio dauginimosi dalys, 10,85% -žiedai, 8,56% -šakelės, 8,45% -prielapiai. Nuokritų ir jų dalių kiekis nebuvo patikimai susijęs su klimato sąlygų kaita ar miško struktūra. Nustatyta, kad bendras R. apiculata ir X. granatum nuokritų gausumas nepriklauso nuo sezono, tačiau R. apiculata lapų nuokritų gausumas ženkliai skyrėsi pereinamojo (sausio-balandžio) ir drėgnojo (rugsėjo-gruodžio) sezonų metu. Sibuti mangrovėje nuokritų susidarymo produktyvumas yra didesnis nei kitose pasaulio tropinėse mangrovėse. Didesnis šio miško produktyvumas daugiau priklauso nuo maisto medžiagų kiekio, gamtos natūralumo ir miško brandos negu nuo klimatinių sąlygų. T...

Homestead ponds may offer an ideal opportunity in contribution to household income, fish consumption through fish culture. Phytoplankton plays a key indicator in pond productivity. However, the phytoplankton communities in the homestead ponds are nearly undetermined in Bangladesh. This study summarizes the phytoplankton diversity, assemblage and ecological parameters of the homestead ponds in central coastal belt, Bangladesh, based on two seasons. The results revealed that significant differences (p < .05) were found in pH, DO, conductivity, TDS, nitrates, phosphates and sulphates except temperature in monsoon, and transparency in both seasons. A total of 34 phytoplankton genera representatives of five major groups were recorded such as Euglenophyceae (41.5%), Chlorophyceae (30.5%), Cyanophyceae (13%), Dinophyceae (10%) and Bacillariophyceae (5%). A significant difference (p < .05) in phytoplankton abundance was found in both seasons with the highest mean of 186.13 ± 129.34 × 10 4 cells L −1 in monsoon and the lowest mean of 144.40 ± 107.26 × 10 4 cells L −1 during winter. The diversity (H'), evenness (J'), richness (d) and dominance (D) ranged from 1.62 to 2.47, 0.52 to 0.97, 0.37 to 1.15 and 0.10 to 0.28 respectively. Based on SIMPER, the most dominant (>10%) genera for dissimilation within stations and seasons were Euglena spp., Phacus spp., Chlorella spp., Strombomonas spp. and Peridinium spp. ANOSIM results stated that 12 genera of phytoplankton were significant contributors based on average dissimilarity. Pearson's correlation coefficient and canonical correspondence analysis (CCA) revealed that phytoplankton abundance, diversity and community were mainly governed by transparency, dissolved oxygen and nitrates.

No 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.

No abstract