Interactions between marine megafauna and plastic pollution in Southeast Asia.

Southeast (SE) Asia is a highly biodiverse region, yet it is also estimated to cumulatively contribute a third of the total global marine plastic pollution. This threat is known to have adverse impacts on marine megafauna, however, understanding of its impacts has recently been highlighted as a priority for research in the region. To address this knowledge gap, a structured literature review was conducted for species of cartilaginous fishes, marine mammals, marine reptiles, and seabirds present in SE Asia, collating cases on a global scale to allow for comparison, coupled with a regional expert elicitation to gather additional published and grey literature cases which would have been omitted during the structured literature review. Of the 380 marine megafauna species present in SE Asia, but also studied elsewhere, we found that 9.1 % and 4.5 % of all publications documenting plastic entanglement (n = 55) and ingestion (n = 291) were conducted in SE Asian countries. At the species level, published cases of entanglement from SE Asian countries were available for 10 % or less of species within each taxonomic group. Additionally, published ingestion cases were available primarily for marine mammals and were lacking entirely for seabirds in the region. The regional expert elicitation led to entanglement and ingestion cases from SE Asian countries being documented in 10 and 15 additional species respectively, highlighting the utility of a broader approach to data synthesis. While the scale of the plastic pollution in SE Asia is of particular concern for marine ecosystems, knowledge of its interactions and impacts on marine megafauna lags behind other areas of the world, even after the inclusion of a regional expert elicitation. Additional funding to help collate baseline data are critically needed to inform policy and solutions towards limiting the interactions of marine megafauna and plastic pollution in SE Asia.

Abandoned, lost, or discarded fishing gear at urban coastlines.

Abandoned, lost, or discarded fishing gear (ALDFG) is considered a major threat to ocean biodiversity. Yet, little is known of the interactive impacts of ALDFGs and urban nearshore biodiversity and habitats, especially in Southeast Asia where fisheries efforts are increasing. We identified ALDFG hotspots around Singapore-where 80% of coastal areas are urbanized or anthropogenically modified. Fishing lines and nets were the most common ALDFGs recovered; with strong correlations between ALDFG presence and beaches, intertidal, mangroves, as well as sites with significant coastal modifications. Plastic polymer nets trapped the highest organism diversity and abundance. A total of 1052 trapped individuals comprising 124 species were recovered, the majority in classes Merostomata, Actinopterygii and Malacostraca. The most abundant trapped species was Carcinoscorpius rotundicauda and the highest mortality presentation was in Class Actinopterygii. This study demonstrates that ALDFGs remain a threat to marine biodiversity within urban coastal habitats and at heavily modified shorelines.

Taxonomical and morphological notes on two species of mudskippers, Periophthalmus walailakae and Periophthalmodon schlosseri (Teleostei: Gobiidae) from Singapore.

The mudskipper Periophthalmus walailakae is recorded from Singapore, where it was previously misidentified as Periophthalmodon schlosseri, with which it is syntopic. Periophthalmus walailakae is distinguished from its congeners by the following combination of characters: pelvic fins completely united and shaped like a disk, and first dorsal fin dark brown or black, with a rounded posterior edge and a white distal margin. This species most closely resembles Pn. schlosseri but has one row of teeth on the upper jaw, scales on the isthmus, and a different upper lip and jaw morphology. Contrary to an earlier report, scales are present on the snout, interorbital, and isthmus of Ps. walailakae. The two species can also be distinguished by size, external morphology, and body color patterns.