Plastic pollution is recognized as a severe anthropogenic issue in the coastal and marine ecosystems across the world. Unprecedented and continuous accumulation of growing plastic contaminants into any respective aquatic ecosystem by the anthropogenic sources causes direct and/or indirect interruption to ecosystem structure, functions, and consequently, services and values. Land-based and sea-based sources are the primary sources of these contaminants in various modes that enter the ocean. In this review paper, we focused on highlighting different aspects related to plastic pollution in coastal and marine environments. Plastic pollutants are distributed in the ecosystems in different forms, with different size variations as megaplastic, macroplastic, mesoplastic, and microplastic. Microplastics in primary and secondary forms reveal a widespread distribution in the water, sediment, and biota of the marine and coastal habitats. The microplastic level of different coastal and marine ecosystems nearly ranged from 0.001-140 particles/m 3 in water and 0.2-8766 particles/m 3 in sediments at different aquatic environments over the world. The microplastic accumulation rate of coastal and marine organisms varied at 0.1-15,033 counts. Accordingly, plastic pollution creates several kinds of negative consequences combined with ecological and socio-economic effects. Entanglement, toxicological effects via ingestion of plastics, suffocation, starvation, dispersal, and rafting of organisms, provision of new habitats, and introduction of invasive species are significant ecological effects with growing threats to biodiversity and trophic relationships. Degradation (changes in the ecosystem state) and modifications of marine systems are associated with loss of ecosystem services and values. Consequently, this emerging contaminant affects the socio-economic aspects through negative impacts on tourism, fishery, shipping, and human health. Preventing accumulation sources of plastic pollutants, 3Rs (Reduce-Recycle-Reuse), awareness & capacity building, and producer/manufacturer responsibility are practical approaches toward addressing the issue of plastic pollution. Existing and adopted policies, legislations, regulations, and initiatives at global, regional, and national level play a vital role in reducing plastic debris in the marine and coastal zones. Development of proposals/solutions on key research gaps can open a novel pathway to address this environmental issue in an effective scientific manner. In conclusion, this paper demonstrates the current status of plastic pollution in the marine ecosystem to make aware people of a plastic-free, healthy blue ocean in the near future.

This study assessed the microplastic contamination of 3 most abundant sessile and intertidal invertebrates (Rock Oyster: Saccostrea forskalii, Striped Barnacle: Balanus amphitrite, Periwinkle: Littoraria sp.) in 3 beaches of the eastern coasts of Thailand. The results showed a significant accumulation of microplastics in the invertebrates at rates of 0.2-0.6 counts/g indicating higher pollution levels along the coastline. Filter feeding organisms showed comparatively higher accumulation rates of microplastics. Thus, contaminated bivalves pose potential health risks for seafood consumers. The plastic pollutant prevalence in sessile and intertidal communities was corresponded with pollution characteristics of contaminated beach habitats where they live. Thus, bivalves, gastropods and barnacles can be used as indicators for contamination of microplastics in the areas. This study also demonstrated the need for controlling plastic pollution in Thai coastal areas.

Lobster fishery is one of the most economically important marine coastal fishing activities. However, genetic identification and taxonomic status of available lobster species are poorly understood in Sri Lanka. The DNA barcoding based on the amplification of partial mitochondrial Cytochrome oxidase I (COI) gene region provides an effective approach for the rapid identification of species status and evaluation of species richness. The present study attempted to collect genetic information of barcoding region for five spiny lobster species that are available in the southern coast of Sri Lanka and to estimate the phylogenetic relationships with the data available for relevant spiny lobsters of other geographic locations. For this purpose, additional sequences were downloaded from the NCBI Genbank and phylogenetic trees were constructed using Maximum Parsimony, Maximum Likelihood and Neighbour Joining methods. Identical tree topologies were resulted from the three methods, and three major clades could be identified. The first clade consisted of Panulirus penicillatus + P. longipes. Panulirus homarus + P. versicolor + P. ornatus were grouped into the second clade whereas the third clade included P. homarus + P. penicillatus + P. longipes. It is important to observe that P. homarus samples collected from southern Sri Lanka grouped with both sub species P. h. homarus and P. h. megasculpta indicating their availability in the sampling regions. Although three subspecies are available in P. longipes, the samples from southern Sri Lankan grouped only with P. l. longipes. High intra-specific nucleotide diversity was reported in for Sri Lankan samples. This indicates that habitats around southern coast of Sri Lanka possess suitable environmental conditions to inhabit diverse Panulirus populations. These results would be highly useful to plan management and conservation strategies for Panulirus populations in Sri Lanka.

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Risso's dolphin (Grampus griseus Cuvier, 1812) is the only species of genus Grampus and a cosmopolitan marine inhabitant. Here, we report a polymorphic complete mitochondrial genome of G. griseus. The size of the total mitochondrial genome was 16,386 bp in length and contains 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a control region. 37 single nucleotide polymorphic sites (SNPs) were identified compared to the references. Based on the available total mitochondrial dolphin genomes' phylogenetics, G. griseus has formed a clade with 0.1415 distance, sister to the following species of the subfamily Globicephalinae and the taxonomy of Orcinus orca still needs further investigations.

The present study was aimed to investigate the quality of home range habitat characteristics of the scalloped spiny lobster Panulirus homarus (Linnaeus, 1758) in southern coastal region of Sri Lanka. Four sites were selected from south-east (Patanagalle, Godawaya) and south-west (Weligama, Hikkaduwa) regions of the southern coast of Sri Lanka (SCSL). The bottom water quality data and benthic substrate types of their home range habitats were monitored and noted in a 25 x 25 m area covering 16 subsampling points with locality information. With the use of geographical information system (GIS) tools, the spatial distribution maps of environmental parameters were created and submerged bottom substrate types of the four sites were graphed. Salinity, temperature and dissolved oxygen correlated well with depth. Hikkaduwa site was found rich in corals with less number of scalloped spiny lobsters. Sites of south-east region of the SCSL (Patanagalle, Godawaya) were found less polluted having rocks and sandy bottom with high occurrence of scalloped spiny lobsters. Results of the study showed that Patanagalle site (south-east of SCSL) could be suggested as the most suitable site for culturing scalloped spiny lobsters.

Fat metabolism in toothed whales is different from other mammals. RT-qPCR is still a reliable technique for studying the relative expressions of various genes involved in metabolism. This study was done for Risso’s dolphin, a toothed whale and information produced here will be important for further transcriptomics studies focused on unrevealed marine mammal fat metabolism. In this study, we sought to identify a suitable reference gene with minimum resources. Seven candidate reference genes ZC3H10, FTL, LGALS1, RPL27A, GAPDH, FTH1 and DCN were initially tested for amplification efficiency using RT-qPCR by producing standard curves. Then, three nearly 100% efficient genes FTL, LGALS1 and GAPDH were selected for the gene stability analysis to determine one stable gene across eight different fat tissues, liver, and muscle of Risso’s dolphins based on four algorithms, provided in geNorm, NormFinder, BestKeeper and Delta Ct. Finally, a RefFinder comprehensive ranking was done based on stability values and the genes were ranked as: FTL>LGALS1>GAPDH. The FTL and LGHLS were identified as the most stable genes; however, GAPDH was third, a well-known housekeeping gene for mammals. Finally, we suggest using FTL as a reliable reference gene for functional genomics studies on toothed whales in the future.

Jaw fats play a key role in echolocation in toothed whales. These fats are located along the outer and inner segments of the lower jawbone. A ribose nucleic acid (RNA) sequencing technique was employed to investigate transcriptomes of these two types of jaw fat tissues in Risso’s dolphins. We identified 1,899 upregulated common genes in both fat tissues. The differentially-expressed genes (DEGs) analysis showed that 34 and nine known genes were significantly upregulated in outer and inner jaw fats, respectively. A functional enrichment analysis was conducted by Enricher; lipid metabolism-related gene ontologies (GO) and pathways were identified (p<0.05). Based on these analyses, APOH, HNF4A, MYF6, SLC1A2, SLC2A2 and ALDOB were key genes for lipid metabolism in the outer jaw fat which are mainly involved with lipoprotein lipase activities. However, APP, DHX9, PXMP4 and THBS4 genes were highly expressed in the inner jaw fat, and their main functional enrichments were amyloid-beta formation and the activation of ECM-receptor interaction. These recent findings provide evidence for de novo lipid synthesis and as a new concept, the APP may be involved with transferring sound wave signals from the inner jaw fat to the brain via neurons, and further studies are necessary for revealing the puzzle of echolocation in toothed whales.