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The ubiquitous presence of microplastics (MPs) across all oceans has emerged as a significant marine hazard as worldwide plastic production continues to grow. Now and during the next 20-30 years will be the time to confront the implications of the plastic industry's rise, which has resulted in the large-scale global production of millions of plastic-based items, varying from a single pen to automobiles. Inappropriate management, lack of awareness of the detrimental effects, reckless universal use, and the indiscriminate disposal of plastic based synthetic materials, has turned Earth into a "plastic planet”. It is critical to have a throughout understanding of MPs' potential from sink to source as well as the processes that govern their distribution and uptake and exchange in ecosystems, to properly comprehend their potential consequences and ecological harm. The goal of the present study was to identify the scenarios of microplastics structure, functions and subsequent impact to the marine organisms. Diversified origins of MPs in the oceans and their negative effects on marine animals have been discussed critically in this review. Because of their small size, these plastic particles are easily ingested by a wide range of marine life (e.g., fish, Mollusca, Arthropoda, Annelida, Echinodermata, Nematoda, phytoplankton, zooplankton, algae, birds, Mammalia, marine reptiles, and coral), putting their health at risk. The ability of MPs to absorb a variety of dangerous hydrophobic chemicals from the environment directly transfers these toxins into the food chain. As a result, many laws and rules have been created to address the major issue of MP pollution in the marine ecosystem and it must be improved and implemented worldwide. To avert future dangers, it is critical to stop producing it and replace it with environmentally suitable alternatives.

The Sundarban Mangrove Forest (SMF) is an intricate ecosystem containing the most varied and profuse natural resources of Bangladesh. This study presents empirical research, based on primary and secondary data, regarding the social-ecological system (SES), social-ecological dynamics, different stakeholders and relevant management policies of small-scale or artisanal fisheries such as the SMF; showing how, despite extensive diversification, the livelihood activities of the artisanal fishers in the SMF all depend on the forest itself. Regardless of this critical importance of mangroves, however, deforestation continues due to immature death of mangroves, illegal logging, increased salinity, natural disasters and significant household consumption of mangrove wood by local people. As the mangroves are destroyed fish stocks, and other fishery resources are reduced, leading to moves of desperation among those whose livelihood has traditionally been fishing. The present study also considers several risks and shock factors in the fishers' livelihood: attacks by wild animals (especially tigers) and local bandits, illness, natural disasters, river bank erosion, and the cost of paying off corrupt officials. The artisanal fishers of the SMF have adopted different strategies for coping with these problems: developing partnerships, violating the fisheries management laws and regulations, migrating, placing greater responsibility on women, and bartering fishing knowledge and information. This study shows how the social component (human), the ecological component (mangrove resources) and the inter-phase aspects (local ecological knowledge, stakeholder's interest, and money lenders or middle man roles) of the SMF as an SES are linked in mutual interaction. It furthermore considers how the social-ecological dynamics of the SMF have negative impacts on artisanal fishermen's livelihoods. Hence there is an urgency to update existing policies and management issues for the sustainable utilization of the SMF resources, eventually contributing to theimprovement of the artisanal fishers' livelihoods.

It is increasingly recognized that Estuarine Set Bag Net (ESBN) is very popular gear in the coastal fishing community of Bangladesh. In order to reveal the species composition of the ESBN catch and to study the impact of environmental parameters on the spatio-temporal variation of fish assemblages, a one-year baseline survey was conducted in coastal waters of the Moheshkhali Island, northern Bay of Bengal, Bangladesh. A total of 59 taxa were identified of which 47 were finfishes, 7 were shrimps and 5 were from other categories i.e. crab, holothruim, lobster, squid and squila. Among them, 54 species were commonly distributed in all four seasons and stations with 23 and 24 species were found dominant to the total communities in different seasons and sites, respectively. Similarity percentage analysis revealed significant variation in structure and composition of total communities in temporal and spatial scale: (1) the highest (89.33%) and lowest (70.10%) average species similarity was observed in monsoon and winter, respectively; (2) the average species similarity was found highest in Sonadia (88.30%) and lowest in Nalbila (74.83%). SIMPER analysis demonstrated that the contributory species (i.e. Crab, Squid, Pampus chinensis, Chirocentrus nudus, Ascetes sp. Penaeus monodon, Metapenaeus brevicornes, Arius sp., Tenualosa ilisha, Uranoscopus sp., Machrobrachium ruddis, Gerres filamentosus, Coillia dussumieri, Squila, Glossogobius giuris, Rastrelliger kanagurta, Rhynchorhamphus georgii, Chirocentrus nudus, Ascetes sp., Metapenaeus brevicornes, Tenualosa ilisha, Uranoscopus sp., Rhynchorhamphus georgii, Penaeus indicus) varied among different sites and seasons. One-way ANOVA and Canonical Correspondence Analysis (CCA) revealed that the total communities were significantly driven by temperature, salinity, pH, DO and water transparency. Multivariate analyses showed that the diversity of ESBN fishery is high in this Island. These findings signify that this coastal zone is one of the nursery grounds and highly diversified for many marine fishes.

Oceanic marine plastic contamination was an increasingly global issue due to increased demand. This has a significant effect not only on marine biodiversity, but also on public safety and numerous infectious diseases found in both aquatic and human species. A huge amount of money was spent worldwide on plastic waste. In the 1940s, plastics development began and is increasing massively. This crucial analysis intends to accomplish goals such as defining plastic materials, origins, detecting aggregation, and validating appropriate techniques to analyze plastic abundance spatio-temporal trends. This further addresses the possible impacts of plastics on marine species, humans, and future chemical emission control strategies together with advice. Plastics are primarily distributed along the coasts and mid-ocean vortex in large amounts. The broad variety of plastics, as eaten by aquatic animals finds their way to the human body through the food chain. Research articles should help learn the origins, deterioration mechanisms, and harmful effects of plastics on both the human body and the ecosystem. Until recently, the science community and politicians have generally ignored plastic waste, but ecological implications, as well as plastic pollution’s economic/health effects, have now gained greater global interest.

Diet analysis revealed that Apocryptes bato is a carnivorous fish. It depends on shrimps and non-shrimp crustaceans mainly. Shrimps include Acetes , penaeid and metapenaeid juveniles, whereas non-shrimp crustaceans include copepods, crab larvae, mysids and amphipods predominantly. The total body lengths (TL) varied between 11.20 and 22.20 cm and weight 16.70 to 43.50 g in male fish. The form of the equation for TL and weight relationship was W = 0.44TL 2.57 and for standard length (SL) it was W = 1.009SL 2.66 . Condition factor (K) ranged from 0.87 to 1.23. The TL was 15.00 to 26.00 cm and weight as 25.1 to 38.50 g in female. The equation was W = 1.001TL 2.52 for TL and W = 1.003SL 2.63 for SL and K value ranged from 0.95 to 1.106. The coefficient of correlation was tested with t test and found highly significant at the 5% level of significance for TL and SL both in the case of male and female. Journal of Bangladesh Academy of Sciences, Vol. 40, No. 1, 57-64, 2016

This research aims at studying the temporal distribution of fish assemblage in the Karnafully river estuary, Bangladesh. To study the fish assemblage catch from Estuarine Set Bag Net (Behundijal) as well water samples were collected in four seasons (winter, pre-monsoon, monsoon and post-monsoon) from March 2013 to February 2014. Multivariate analyses were performed using the software PRIMER V6 and Canonical Correspondence Analysis (CCA) was done using the PAST software. In the present study, 41 species of fish were identified where, Harpodon nehereus (20.54%) was found to be most dominant species. The Shannon-Wiener diversity index (2.67 ± 0.05), Margalef richness index (5.14 ± 0.64), Pielou’s evenness index (0.96 ± 0.007) was high, while Simpson dominance index (0.95 ± 0.002) was low in the monsoon season, which indicates monsoon had high fish diversity than the other seasons. At the similarity of 50.5%, three groups were attained while, monsoon-2 showed separate clustering from other groups. The Non-metric Multidimensional Scaling (nMDS) showed 20% similarity in all seasons based on Bray-Curtis similarity matrix. The CCA ordination indicated that salinity and DO were the two most important environmental parameters shaping the fish assemblage structure in the Karnafully river estuary.

The occurrence of Porpita porpita is reported, for the first time, in the coral island of St. Martin’s located in the southeastern coastal region of Bangladesh. P. porpita was found to occur in the lower littoral zone and beach rock pools, together with molluscan species, and collected during the pre-monsoon season when both water temperature (> 30°C) and salinity (> 30‰) tend to reach a maximum. This study recounts some details on the discovery and description of the species, and thus extends the global distribution and range limits of the genus Porpita.

The coastal ecosystem of the Bay of Bengal (BOB) is described using a mass-balance model of trophic interactions to understand the effects of Set Bag Net on the ecosystem. The BOB model had 14 functional ecological groups; 13 living and one dead (detritus). The result showed that the fishery was heavily exploited and operated at a mean trophic level of 2.45. The SBN fishery was characterized with high fishing mortality rates and large omnivory indices for most of the commercially exploited demersal and pelagic groups. The total primary production requirement for sustainable catch was estimated at 15.11%. However, results of Ecosim simulations elucidated that the key resources, like small demersal, small to medium pelagic fish groups and penaeid shrimps, were likely to show a rapid decline in yields within five years with a twice increase in fishing effort and pressure. In contrast, the palaemonidae and sergested shrimp yields showed an increasing trend as they seem to be able to sustain the high fishing pressure, since their predators are also harvested. In addition to that, cephalopod, which is a non-targeted group for this fishery, is also likely to increase in yield for the time being. The two most drastically affected groups in both fisheries were likely to be shark and small demersal. Continuously increasing fishing effort using SBN will lead to a rapid decline of most of the commercial marine resources and predicted to have a serious effect on the ecosystem functioning of BOB.

A mass-balanced trophic model was developed for the shallow coastal ecosystem of the Bay of Bengal (BOB) using a user friendly software model, Ecopath with Ecosim, (Ecopath, version 5.0 Beta). The BOB model encompassed an area of 24,000 km 2 and had 14 functional ecological groups of which 13 were living groups and one dead group (detritus). The model assessed the trophic relationship, energy flow and interactions between ecological groups. Trophic levels of the compartments varied between 1·0 (for primary producers and detritus) to 3.85 (for shark). The producers particularly phytoplankton and detritus are exploited considerably; hence energy transfer from lower trophic levels was found to be high. Furthermore, all consumers had ecotrophic efficiency (EE) >0.90 indicating that the consumers are heavily exploited in the system. The overall transfer efficiency of the system is 5.9%. The primary production/respiration ( P p/ R ) ratio was found to be 1.351, which indicated that BOB ecosystem is in the developmental stage and has some sorts of system maturity. The BOB ecosystem showed low ecological efficiency with a value of 0.001547 for the gross efficiency of the fisheries. Mixed trophic impact analysis indicated both phytoplankton and zooplankton to have a positive effect on most of the fish functional groups. The values of ascendancy (38.7) and overhead (61.3) showed the stability of the ecosystem. Findings obtained from the present model confirm that coastal ecosystem of BOB is an exploited ecosystem. This trophic model analysis and comparison with previous studies provides an opportunity to pinpoint critical gaps in the present knowledge about coastal ecosystem of BOB for the implementation of the proper fisheries management guidelines.

This paper covers spatial and temporal variation in phytoplankton communities and physico-chemical water properties in the cage culture area of Sepanggar Bay, Sabah, Malaysia based on field measurement conducted during July 2005 to January 2006 to study the spatial and temporal variation in phytoplankton communities and physico-chemical water properties of the bay. Phytoplankton samples and water parameters data were collected from five different stations located inside the bay during Southwest, Interseasonal and Northeast monsoons. Forty phytoplankton genera, representatives of 23 families, were found in the study area with a mean abundance of 1.55 ± 1.19 A— 106 cells L-1. Most of these genera belong to diatoms (82.17%), Dinoflagellates (17.55%) and cyanobacteria (0.29%). Three genera were found to be dominant (>10%) in phytoplankton abundance and these were Coscinodiscus spp. (36.38%), Chaetoceros spp (17.65%) and Bacteriastrum spp. (10.98%). The most dominant genus was Coscinodiscus spp. which showed high abundance during all monsoons and stations (except Station 3). Among the seven environmental parameters tested in this study, water temperature, pH and suspended sediment concentration were found to be significantly different between monsoons. On the other hand, no significant differences were found between stations for the studied physico-chemical parameters. A clear differences in phytoplankton densities were observed between monsoons and stations with higher mean abundances during interseasonal monsoon (2.40 ± 1.37 A— 106 cells L-1) and at station five (2.05 ± 0.74 A— 106 cells L-1), respectively. Conversely, the diversity indices, both Shannon-Wiener (H′) and Pielou (J′), showed no significant difference throughout stations and monsoons (except (H′) for monsoons). Analysis of similarity (ANOSIM) results demonstrated temporal differences in phytoplankton community structure with highly diverse phytoplankton assemblage. Through cluster analysis five groups of phytoplankton were attained (at 40% similarity level) though no marked separation of the taxonomic classes pointed towards the constant pattern of the phytoplankton assemblage in the studied area. © 2008 Elsevier Ltd. All rights reserved.