In-situ analysis of small microplastics in coastal surface water samples of the subtropical island of Okinawa, Japan

Marine plastic debris is widely recognized as a global environmental issue. Sun-micron plastic particles, with an upper size limit of 20 um, have been identified as having the highest potential for causing damage to marine ecosystems. Having accurate methods for quantifying the abundance of such particles in a natural environment is essential for defining the extent of the problem they pose. Using an optical micro-Raman tweezers setup, we have identified the composition of particles trapped in marine aggregates collected from the coastal surface waters around the subtropical island of Okinawa. Chemical composition analysis at the single-particle level indicates dominance by low-density polyethylene, which accounted for 75% of the total sub-micron plastics analyzed. Our results show the occurrence of plastics at all test sites, with the highest concentration in areas with high human activities. The average, smallest sub-micron plastics size is (2.53 +/- 0.85)um for polystyrene. We also observed additional Raman peaks on the plastics spectrum with decreasing debris size which could be related to structural modification due to weathering or embedding in organic matter. By single-particle level sub-micron plastics identification, we can begin to understand their dispersion in the ocean and define their toxicity and impacts on marine biodiversity and food chain.Comment: 9 page

Response of Coral Reef Dinoflagellates to Nanoplastics under Experimental Conditions Suggests Downregulation of Cellular Metabolism

Plastic products contribute heavily to anthropogenic pollution of the oceans. Small plastic particles in the microscale and nanoscale ranges have been found in all marine ecosystems, but little is known about their effects upon marine organisms. In this study, we examine changes in cell growth, aggregation, and gene expression of two symbiotic dinoflagellates of the family Symbiodiniaceae, Symbiodinium tridacnidorum (clade A3), and Cladocopium sp. (clade C) under exposure to 42-nm polystyrene beads. In laboratory experiments, the cell number and aggregation were reduced after 10 days of nanoplastic exposure at 0.01, 0.1, and 10 mg/L concentrations, but no clear correlation with plastic concentration was observed. Genes involved in dynein motor function were upregulated when compared to control conditions, while genes related to photosynthesis, mitosis, and intracellular degradation were downregulated. Overall, nanoplastic exposure led to more genes being downregulated than upregulated and the number of genes with altered expression was larger in Cladocopium sp. than in S. tridacnidorum, suggesting different sensitivity to nano-plastics between species. Our data show that nano-plastic inhibits growth and alters aggregation properties of microalgae, which may negatively affect the uptake of these indispensable symbionts by coral reef organisms

Analysis of small microplastics in coastal surface water samples of the subtropical island of Okinawa, Japan

Marine plastic debris is widely recognized as a global environmental issue. Small microplastic particles, with an upper size limit of 20 mu m, have been identified as having the highest potential for causing damage to marine ecosystems. Having accurate methods for quantifying the abundance of such particles in a natural environment is essential for defining the extent of the problem they pose. Using an optical micro-Raman tweezers setup, we have identified the composition of particles trapped in marine aggregates collected from the coastal surface waters around the subtropical island of Okinawa. Chemical composition analysis at the single-particle level indicates dominance by low-density polyethylene, which accounted for 75% of the small microplastics analysed. The smallest microplastics identified were (2.53 ± 0.85) mu m polystyrene. Our results show the occurrence of plastics at all test sites, with the highest concentration in areas with high human activities. We also observed additional Raman peaks on the plastics spectrum with decreasing debris size which could be related to structural modification due to weathering or embedding in organic matter. By identifying small microplastics at the single-particle level, we obtain some indication on their dispersion in the ocean which could be useful for future studies on their potential impact on marine biodiversity

Dinoflagellate nucleus contains an extensive endomembrane network, the nuclear net

Dinoflagellates are some of the most common eukaryotic cells in the ocean, but have very unusual nuclei. Many exhibit a form of closed mitosis (dinomitosis) wherein the nuclear envelope (NE) invaginates to form one or more trans-nuclear tunnels. Rather than contact spindles directly, the chromatids then bind to membrane-based kinetochores on the NE. To better understand these unique mitotic features, we reconstructed the nuclear architecture of Polykrikos kofoidii in 3D using focused ion beam scanning electron microscopy (FIB-SEM) in conjunction with high-pressure freezing, freeze-substitution, TEM, and confocal microscopy. We found that P. kofoidii possessed six nuclear tunnels, which were continuous with a reticulating network of membranes that has thus far gone unnoticed. These membranous extensions interconnect the six tunnels while ramifying throughout the nucleus to form a "nuclear net." To our knowledge, the nuclear net is the most elaborate endomembrane structure described within a nucleus. Our findings demonstrate the utility of tomographic approaches for detecting 3D membrane networks and show that nuclear complexity has been underestimated in Polykrikos kofoidii and, potentially, in other dinoflagellates

Micro- and Nanoplastic in Okinawa: Potential impacts on planktonic microalgae and Endosymbiotic Dinoflagellates

From coast to gyre, from surface to deep sea, the study of marine plastic pollution takes us on a journey of potential harm through our marine ecosystems, where man-made plastics break down into ever smaller pieces along their way. Studying micro- and nanoplastic pollution in field and laboratory work, new insights into microalgae interactions, and these smallest plastic particles were gathered. Mimicking two different environments in the laboratory - reef and open ocean water - an effect assessment of four different microalgae species (Diatoms Skeletonema grethae and Odontella aurita, cyanobaterium Synechococcus elongatus, endosymbiontic dinoflagellates Symbiodinium tridacnidorum and Cladocopium sp.) and their interaction with micro- and nanoplastics at different sizes, types, and concentrations was conducted. Aggregation, sedimentation, photosynthesis, extracellular substance production, and RNA expression patterns were all found to be affected. Specifically, hetero-aggregation with nanoplastic led to neutrally buoyant marine snow, differentially expressed genes, and reduced photosynthesis. Furthermore, an exposure assessment around Okinawa, an isolated subtropical island with fringing reefs, found that microplastic pollution follows the island’s population gradient. Polyethylene was the most abundant polymer found 45%, and of the ubiquitous sub 20 μm plastics, the majority was embedded in organic matter.Okinawa Institute of Science and Technology Graduate Universit

Micro- and Nanoplastic in Okinawa: Potential impacts on planktonic microalgae and Endosymbiotic Dinoflagellates

From coast to gyre, from surface to deep sea, the study of marine plastic pollution takes us on a journey of potential harm through our marine ecosystems, where man-made plastics break down into ever smaller pieces along their way. Studying micro- and nanoplastic pollution in field and laboratory work, new insights into microalgae interactions, and these smallest plastic particles were gathered. Mimicking two different environments in the laboratory - reef and open ocean water - an effect assessment of four different microalgae species (Diatoms Skeletonema grethae and Odontella aurita, cyanobaterium Synechococcus elongatus, endosymbiontic dinoflagellates Symbiodinium tridacnidorum and Cladocopium sp.) and their interaction with micro- and nanoplastics at different sizes, types, and concentrations was conducted. Aggregation, sedimentation, photosynthesis, extracellular substance production, and RNA expression patterns were all found to be affected. Specifically, hetero-aggregation with nanoplastic led to neutrally buoyant marine snow, differentially expressed genes, and reduced photosynthesis. Furthermore, an exposure assessment around Okinawa, an isolated subtropical island with fringing reefs, found that microplastic pollution follows the island’s population gradient. Polyethylene was the most abundant polymer found 45%, and of the ubiquitous sub 20 μm plastics, the majority was embedded in organic matter.Okinawa Institute of Science and Technology Graduate Universit

Linking Marine Ecosystem Services to the North Sea’s Energy Fields in Transnational Marine Spatial Planning

Marine spatial planning temporally and spatially allocates marine resources to different users. The ecosystem approach aims at optimising the social and economic benefits people derive from marine resources while preserving the ecosystem’s health. Marine ecosystem services are defined as the benefits people obtain from marine ecosystems. The aim of this study is to determine which interrelations between marine ecosystem services and the marine energy industry can be identified for use in transnational marine spatial planning exemplified in the North Sea region. As the North Sea is one of the busiest seas worldwide, the risk of impairing the ecosystems through anthropogenic pressures is high. Drawing on a literature-based review, 23 marine ecosystem services provided by the North Sea region were defined and linked to seven offshore energy fields comprising oil and natural gas, wind, tides and currents, waves, salinity gradients, algal biomass, and geothermal heat. The interactions were divided into four categories: dependence, impact, bidirectional, or no interaction. Oil and natural gas, as well as algae biomass, are the fields with the most relations with marine ecosystem services while waves and salinity gradients exhibit the least. Some marine ecosystem services (Conditions for Infrastructure, Regulation of Water Flows, and Cognitive Development) are needed for all fields; Recreation and Tourism, Aesthetic and Cultural Perceptions and Traditions, Cognitive Development, and Sea Scape are impacted by all fields. The results of this research provide an improved basis for an ecosystem approach in transnational marine spatial planning