Assessing CO2 sources and sinks in and around Taiwan: Implication for achieving regional carbon neutrality by 2050.

Taiwan has pledged to achieve net-zero carbon emissions by 2050, but the current extent of carbon sinks in Taiwan remains unclear. Therefore, this study aims to first review the existing nature-based carbon sinks on land and in the oceans around Taiwan. Subsequently, we suggest potential strategies to reduce CO2 emissions and propose carbon dioxide removal methods (CDRs). The natural carbon sinks by forests, sediments, and oceans in and around Taiwan are approximately 21.5, 42.1, and 96.8 Mt-CO2 y-1, respectively, which is significantly less than Taiwan's CO2 emissions (280 Mt-CO2 y-1). Taiwan must consider decarbonization strategies like using electric vehicles, renewable energy, and hydrogen energy by formulating enabling policies. Besides more precisely assessing both terrestrial and marine carbon sinks, Taiwan should develop novel CDRs such as bioenergy with carbon capture and storage, afforestation, reforestation, biochar, seaweed cultivation, and ocean alkalinity enhancement, to reach carbon neutrality by 2050.

Genetic stock structure of the silky shark Carcharhinus falciformis in the Indo-Pacific Ocean.

The silky shark, Carcharhinus falciformis, is a cosmopolitan species commonly caught as a bycatch for longline fisheries. However, the genetic stock structure for the Indo-Pacific Ocean is not well-defined yet. Here, we used eight microsatellite loci to examine the genetic stock structure and effective population size of 307 silky sharks across 5 Indo-Pacific sampling locations. A major genetic break was found between Aceh and the remaining locations (FST = 0.0505-0.0828, p = 0.001). The Indian Ocean displayed a slightly lower effective population estimate (Ne) compared to the Pacific Ocean, potentially due to the higher fishing pressure in the Indian Ocean region. The lowest Ne was found in the Aceh population (Ne = 2.3), suggesting it might be a small and endemic population. These findings offer valuable information for the conservation and management of the silky shark. We suggest that the population around Aceh waters constitutes a distinct stock and should be managed independently. Further investigations into migratory and movement patterns are needed to define the boundaries of different stocks, ensuring effective management the silky shark across the Indo-Pacific region.

Carbon capture by macroalgae Sarcodia suae using aquaculture wastewater and solar energy for cooling in subtropical regions.

Rapid growth in the aquaculture industry and corresponding increases in nutrient and organic carbon levels in coastal regions can lead to eutrophication and increased greenhouse gas emissions. Macroalgae are the organisms primarily responsible for the capture of CO2 and removal of nutrients from coastal waters. In the current study, we developed a novel wastewater treatment system in which the red macroalga, Sarcordia suae, is used to capture CO2 under thermostatic conditions in subtropical regions. In 2020 (without temperature control), the carbon capture rate (CCR) of Sarcordia suae varied considerably with the season: winter/spring (2.1-3.9 g-C m-2 d-1) and summer (0.09 g-C m-2 d-1). In 2021, solar powered cooling reduced summer seawater temperatures from 31 to 33 °C to 23-25 °C with a corresponding increase in the mean CCR: winter/spring (2-7 g-C m-2 d-1) and summer (1.33 g-C m-2 d-1). The proposed aquaculture wastewater system proved highly efficient in removing nitrogen (20.7 mg-N g-1 DW d-1, DW = dry weight) and phosphorus (4.4 mg-P g-1 DW d-1). Furthermore, the high density of Sarcodia (1.10 ± 0.03 g cm-3) would permit the harvesting and subsequent dumping of Sarcodia in deep off-shore waters. This study demonstrated a low-cost land-based seaweed cultivation system for capturing CO2 and excess nutrients from aquaculture wastewater year-round under temperature controlled environments in subtropical regions.

Occurrence of microplastics in commercial marine dried fish in Asian countries.

The major risk of microplastics in marine environments is the bioaccumulation in marine organisms. Plastic ingestion by marine organisms has been investigated and recently more attention has been given to microplastics in seafood. However, it is seldom reported the occurrence of microplastics in marine commercial dried fish products available for human consumption. Here, we report the occurrence of microplastics in 14different marine dried fish products from seven Asian countries. Microplastics were observed in most dried fish, with fibers representing ~80% of the total-microplastics. The major plastic polymers, identified using Micro-Raman spectroscopy, included polyethylene (35%), polyethylene terephthalate (26%), polystyrene (18%), polyvinyl chloride (12%), and polypropylene (9%). The highest count, in either per individual (1.92 ± 0.12) or per gram of dried fish (0.56 ± 0.03), were found in Etrumeus micropus from Japan. Marine dried fish, which are typically eaten whole, may contribute to the ingestion of microplastics by humans, posing potential health risks especially in Asian countries. Further studies are needed to identify the occurrence of smaller sized microplastics and nanoplastics and their potential health impacts.

Composition and abundance of marine debris stranded on the beaches of Sri Lanka: Results from the first island-wide survey.

This study provides the first assessment of marine debris washed ashore on 22 beaches along the coast of Sri Lanka. There was an average of 4.1 large (>25 mm) and 158 small (5-25 mm) pieces of debris per square meter of beach. Classified by use, packaging material (55%) dominated the debris, followed by consumer products (25%) and fishing gear (20%). In terms of materials, plastic was the greatest contributor (93%) to marine debris. Beaches near a river mouth or city and those with a barrier had greater debris accumulations. The east coast had significantly greater small debris density, possibly due to strong northeastern monsoon currents. Large spatial heterogeneity was observed in the amount of debris. Long-term monitoring is imperative to better understand the temporal changes in, and the pathways and possible management of, marine debris.