Assessing the efficiency of microplastics extraction methods for tropical beach sediments and matrix preparation for experimental controls

IntroductionMicroplastic pollution has become a global issue, eliciting attention not just from the scientific community but also both from the public and governmental bodies. Drawing data-driven policies and interventions, however, remain difficult due to the severely lacking baseline information from different environments such as beaches. One of the challenges in doing baseline studies is the lack of harmonized methodologies that will allow for comparison of results, integration of data, and its effective translation to evidence-based policies. Emphasis on quality control measures among baselining efforts through the proper implementation of experimental controls is also lacking.MethodologyTo address these gaps, we compared methodologies for preparing the sediment matrix for experimental controls, as well as evaluated protocols for extracting microplastics from tropical beach sediments. Beach sediments were collected, dried, sieved, and spiked with known amounts of microplastics of different polymer types. The removal and extraction efficiencies of the protocols being compared were evaluated.Results and discussionOur results showed that subjecting beach sediments to a furnace at 550° C for 4 hours is the most efficient way to remove plastic contamination, implying its applicability for preparing experimental controls. Meanwhile, a modified version of Masura et al. (2015), one of the widely cited methodologies for microplastics extraction, exhibited the highest mean extraction efficiency (99.05 ± 0.82%) among the protocols being compared. Results of this work will be useful in identifying methods that can be adopted and utilized for research and baselining efforts not just in the Philippines but also in Southeast Asia. This will also be helpful in the harmonization of methods, data reporting, and even skills as implemented through the regional and national action plans to address marine plastic pollution

Development, morphological characteristics and viability of temporary cysts of <i>Pyrodinium bahamense</i> var. <i>compressum</i> (Dinophyceae) <i>in vitro</i>

<div><p>Pellicle or temporary cysts of <i>Pyrodinium bahamense</i> var. <i>compressum</i> (Böhm) Steidinger, Tester & F.J.R. Taylor and their role in bloom dynamics have not yet been adequately characterized and understood. We investigated the role of temperature- and nutrient-mediated stress as factors that could induce pellicle formation in batch cultures. Cellular features and their implications for temporary cyst viability were examined using confocal laser scanning microscopy (CLSM). Our data suggest that temperature change is one of the key factors influencing pellicle formation, preserving viability at low temperature (i.e. 13°C). Hypnocysts (resting cysts) were not observed. During pellicle formation, motile cells generally undergo ecdysis, extrusion of cytoplasmic materials and bacteria, compaction of the nucleus and non-motility. The outermost covering of the temporary cysts shows red autofluorescence and it contains lower concentrations of chlorophyll (chl) <i>a</i> and no detectable chl <i>c.</i> The nuclear region is surrounded by transitional red bodies and other unidentified cellular structures. Temporary cysts can immediately revert back to the motile state upon exposure to optimum conditions. This is accompanied by the expansion of the nuclear region, regeneration of the chloroplasts and enlargement of the cell. Developmental changes during reversal of temporary cysts to motile forms were also observed to cause breaks in the cell covering that could serve as sites for bacterial entry. Though observed <i>in vitro</i>, such behaviour may also be occurring in nature especially as a response to drastic short-lived environmental changes. This is the first detailed report on the characteristics of temporary cysts of <i>P. bahamense</i> var<i>. compressum.</i></p></div

Priorities to inform research on marine plastic pollution in Southeast Asia

10.1016/j.scitotenv.2022.156704Sci Total Environ841156704

Corrigendum to “Priorities to inform research on marine plastic pollution in Southeast Asia” [Sci. Total Environ. volume 841 (2022) Article 156704]

10.1016/j.scitotenv.2022.159595SCIENCE OF THE TOTAL ENVIRONMENT857Pt