Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissemination of high quality research generated in the Western Indian Ocean (WIO) region, in particular on the sustainable use of coastal and marine resources. This is central to the goal of supporting and promoting sustainable coastal development in the region, as well as contributing to the global base of marine science. The journal publishes original research articles dealing with all aspects of marine science and coastal management. Topics include, but are not limited to: theoretical studies, oceanography, marine biology and ecology, fisheries, recovery and restoration processes, legal and institutional frameworks, and interactions/relationships between humans and the coastal and marine environment. In addition, Western Indian Ocean Journal of Marine Science features state-of-the-art review articles and short communications. The journal will, from time to time, consist of special issues on major events or important thematic issues.

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1. Among the several threats to the conservation of mangrove ecosystems in most South Asian countries, shrimp farming is predominant. Since the introduction of shrimp farming in Sri Lanka in the 1980s, mangroves on the island's north-western coast have been continually cleared to create new shrimp farms, leading to a decline in the social-ecological services provided by the mangrove ecosystems. 2. Using aerial (1973) and satellite (1996-2020) images, this study assessed areal changes in mangroves and shrimp farms in the Pambala-Chilaw lagoon complex and Ihala Mahawewa, as well as the ecological footprint of shrimp farming in the study area. 3. Mangroves around the Chilaw lagoon had decreased in areal extent by 45% from 1973 to 2020 of which 92% of this change was attributed to shrimp farming. There was, however, a decrease in the areal extent of shrimp farms from 2001 to 2020, and a corresponding increase in mangroves from 2006 to 2020. 4. The ecological footprint of shrimp farming was assessed by comparing the expected surface ratios with those recorded for shrimp farms with mangroves and surface water bodies in the study area from 1973 to 2020. The results showed that the current shrimp farming was unsustainable (i.e. high ecological footprint).5. While the results support the current view that there is cause for cautious optimism with mangrove conservation (as evidenced by an increase in mangrove areal extent), it also reveals that semi-intensive shrimp farming in Sri Lanka and probably other similar tropical countries is unsustainable.6. If immediate actions such as effective regulation of shrimp farming activities and mangrove restoration are not taken, the mangrove ecosystem will continue to decline.

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Heavy metal (HM) pollution has become a serious threat to coastal aquatic ecosystems. This study, therefore, aimed at assessing the spatial distribution of selected heavy metals/metalloids including Arsenic (As), Cadmium (Cd), Chromium (Cr), Lead (Pb), and Mercury (Hg) in surface sediment (0–15 cm) samples collected across Kalametiya Lagoon in southern Sri Lanka. Forty-one (41) grid points of the lagoon were sampled and the sediment samples were analyzed for HM content by using ICP-MS. A questionnaire survey was carried out to investigate the possible sources for HM pollution in Kalametiya Lagoon. Water pH and salinity showed significant variation across the lagoon. Overall mean value of pH and salinity were 6.68 ± 0.17 and 2.9 ± 2.2 PSU respectively. The spatial distribution of the heavy metals was not monotonic and showed a highly spatial variation. The kernel density maps of the measured heavy metals demarcated several different areas of the lagoon. The mean contents of As, Cd, Cr, Hg, and Pb were lower than that of threshold effect level (TEL) however, higher for Hg at the North Inlet. Nevertheless, it was still lower than potential effect level (PEL). Socio-economic interactions have dramatically reduced during the past two decades. Industrial sewage, river suspended sediments and agrochemicals such as fertilizers, pesticides were reportedly identified as the possible sources for heavy metal loads. Accumulation of toxic heavy metals can be minimized by detouring the water inflow to the lagoon.