Transport of Microplastics in Shore Substrates: Roles of Polymer Characteristics and Environmental Processes

The presence of plastic fragments in the environment is a growing global concern. The coast is particularly vulnerable to microplastic (MP) pollution. However, field experiments are less capable of disentangling the complex interplay of various factors. Therefore, this study aims to investigate the transport of MPs in porous media combined with typical coastal processes. Firstly, a weathering experiment was conducted to comprehensively reveal the changes in MPs in the environment. The results indicated that seawater aging mainly affected the physical properties of MPs, increasing its surface pores and hydrophilicity. Ultraviolent (UV) aging significantly increased its hydrophilicity and crystallinity and introduced oxygen-containing functional groups onto MPs. Then, the detachment of MPs from porous media under various water content conditions combined with flow patterns was studied. For both the wet and dry conditions, the increase in flow rates decreased the detachment of hydrophobic polyethylene (PE) of two sizes and hydrophilic polymethylmethacrylate (PMMA). Transient flows with varied flow rates and ionic strength led to flow peaks and more MP detachment compared to steady flow. Furthermore, substrate drying significantly impeded the detachment of MPs compared to wet conditions irrespective of the flow regimes. The release of MPs decreased pronouncedly with prolonged air drying duration of the column since drying heightens the energy barrier for MPs to detach. Tide is a typical coastal process that has profound influence on many biological and abiotic processes. In the following study, the effects of tidal cycles on transport of MPs (4−6 μm PE1; 125 μm PE2; and 5−6 μm polytetrafluoroethylene, PFTE) in porous media were systemically investigated. Smaller substrate sizes exhibited higher retention percentages compared to those of larger substrate sizes under different tidal cycles. In terms of the size of MPs, a larger size (same density) was found to result in enhanced retention of MPs in the column. As the number of tidal cycles increased, although the transport of MPs from the substrate to the water phase was enhanced, less hydrophobic MPs was washed out more with the change in water level. The results implied that MPs with size far smaller than the substrate tend to end up in the open ocean. To expand our understanding of MP mobilization by tidal movement, the influence of dynamic fluctuations of capillary fringe on the transport of MPs was explored. An increase in the cycles of water table fluctuations enhanced the MPs transport from substrate to the water below. More MPs with larger size were retained in substrate compared to the smaller one. The retention percentages of both PE1 and PTFE in column increased with the elevated ionic strength and the decrease of fluctuation velocity. The results highlight that capillary fringe fluctuation can serve as a pathway to relocate MPs to the tidal aquifer. Finally, a mesoscale tank experiment was conducted to simulate the infiltration and resuspension of MPs in a slope substrate under the influence of repeated tidal forces. The results imply that large, high-density, and less flat particles tend to be distributed in the lower tidal zone and deeper substrate layers. The obtained observation contributes valuable insights into the behavior, transport, and redistribution of MPs in complex environmental systems. The findings enhance our understanding of MP fate and distribution, assisting in the development of strategies for mitigating MP pollution and managing its impact in coastal areas

11th International Coral Reef Symposium Abstracts

https://nsuworks.nova.edu/occ_icrs/1001/thumbnail.jp

Land Use Conflict Detection and Multi-Objective Optimization Based on the Productivity, Sustainability, and Livability Perspective

Land use affects many aspects of regional sustainable development, so insight into its influence is of great importance for the optimization of national space. The book mainly focuses on functional classification, spatial conflict detection, and spatial development pattern optimization based on productivity, sustainability, and livability perspectives, presenting a relevant opportunity for all scholars to share their knowledge from the multidisciplinary community across the world that includes landscape ecologists, social scientists, and geographers. The book is systematically organized into the optimization theory, methods, and practices for PLES (production–living–ecological space) around territorial spatial planning, with the overall planning of PLES as the goal and the promotion of ecological civilization construction as the starting point. Through this, the competition and synergistic interactions and positive feedback mechanisms between population, resources, ecology, environment, and economic and social development in the PLES system were revealed, and the nonlinear dynamic effects among subsystems and elements in the system identified. In addition, a series of optimization approaches for PLES is proposed

Phylogeography and Population Structure in Highly Mobile Marine Taxa in the Western Indian Ocean: Bottlenose Dolphins (Tursiops spp.) and Common Dolphins (Delphinus sp.)

In the marine environment, where barriers to dispersal are limited, taxa normally exhibit genetic homogeneity across large spatial scales. Extraordinarily, marine mammals regularly exhibit genetic differentiation within their cruising range. Furthermore, recent radiation in Delphininae has resulted in several closely related species that remain taxonomically unresolved, particularly bottlenose dolphins (BND) Tursiops spp. and common dolphins (CD) Delphinus spp., making these taxa interesting for studying evolutionary processes. Using mitogenomes and a multi-locus dataset, BNDs from the northwest Indian Ocean (IO) were compared with other recognized species/ecotypes around the world. A new (third) lineage of Indo-Pacific BND, T. aduncus, was identified from the region. Reconstructions of ancestral biogeography and divergence date estimates, suggest a divergence mechanism within T. aduncus that coincides with climate change over the Pleistocene. Reconstructions of ancestral morphology suggest a coastal ancestry for BNDs. Significant population structure was exhibited between T. aduncus populations in the western IO based on mtDNA control region sequences and 14 microsatellite loci. Genetic subdivision appears to correlate with habitat heterogeneity across the study area, which may be driving differentiation through local adaption. Traditional and geometric morphometric techniques were used to investigate congruency between genetic and phenotypic differentiation of three BND lineages in the northwest IO. Strong differences were exhibited in morphology between common BNDs, T. truncatus, and T. aduncus. The T. aduncus lineages were similar, however significant differences in morphology were evident. Significant genetic structure was evident between CD populations off Portugal, South Africa and Oman, based on mtDNA sequences and 14 microsatellites. Further analyses support the taxonomic designation of D. capensis tropicalis in the northwest IO. Both genera exhibit significant population structure over spatial scales outdistanced by their dispersal abilities. Contemporary and historic environmental heterogeneity are suggested as drivers for this structure. Further evidence is provided for the northwest/northern IO as a region of evolutionary endemism, which will inform regional conservation initiatives

Advancing understanding of development policy impacts on transboundary river basins: Integrated watershed modelling of the Lower Mekong Basin.

The management of transboundary river basins across developing countries, such as the Lower Mekong River Basin (LMB), is frequently challenging given the development and conservation divergences of the basin countries. Driven by needs to sustain economic performance and reduce poverty, the LMB countries are embarking on significant land use changes in the form hydropower dams, to fulfill their energy requirements. This pathway could lead to irreversible changes to the ecosystem of the Mekong River, if not properly managed. This thesis aims to explore the potential effects of changes in land use —with a focus on current and projected hydropower operations— on the Lower Mekong River network streamflow and instream water quality. To achieve this aim, this thesis first examined the relationships between the basin land use/land cover attributes, and streamflow and instream water quality dynamics of the Mekong River, using total suspended solids and nitrate as proxies for water quality. Findings from this allowed framing challenges of integrated water management of transboundary river basins. These were used as criteria for selecting eWater’s Source modelling framework as a management tool that can support decision-making in the socio-ecological context of the LMB. Against a combination of predictive performance metrics and hydrologic signatures, the model’s application in the LMB was found to robustly simulate streamflow, TSS and nitrate time series. The model was then used for analysing four plausible future hydropower development scenarios, under extreme climate conditions and operational alternatives. This revealed that hydropower operations on either tributary or mainstream could result in annual and wet season flow reduction while increasing dry season flows compared to a baseline scenario. Conversely, hydropower operation on both tributary and mainstream could result in dry season flow reduction. Both instream TSS and nitrate loads were predicted to reduce under all three scenarios compared to the baseline. These effects were found to magnify under extreme climate conditions, but were less severe under improved operational alternatives. In the LMB where hydropower development is inevitable, findings from this thesis provide an enhanced understanding on the importance of operational alternatives as an effective transboundary cooperation and management pathway for balancing electricity generation and protection of riverine ecology, water and food security, and people livelihoods

Population genetics of Risso’s dolphins (Grampus griseus), Fraser’s dolphins (Lagenodelphis hosei) and bottlenose dolphins (Tursiops spp.) in the North Pacific Ocean

Cetaceans are highly mobile mammals, but many species still exhibit degrees of population structure while inhabiting seemingly boundary-free open waters. Resource specialisation is hypothesized as one of the main drivers of population structure. Using multiple diploid and haploid genetic markers, this study reveals, for the first time, the population genetic structure of Risso’s dolphins, Fraser’s dolphins and common bottlenose dolphins in the tropical-temperate regions of the western North Pacific Ocean. For the Risso’s dolphins, the results showed that there are at least three populations in the North Pacific Ocean, by-and-large parallel to the existing biogeographic provinces; and the direction of gene flow corresponds with the direction of the mainstream currents. Mitochondrial DNA (mtDNA) data showed that the Pacific populations are genetically different from the three populations in the eastern North Atlantic Ocean and the Mediterranean Sea. For the Fraser’s dolphins, the genetic differentiation between Japanese and Philippine waters is consistent with the differentiation suggested in an earlier skull morphometric study. For the common bottlenose dolphins, the results suggested that there are at least four populations in the western and central North Pacific Ocean, and the differentiation appears to correspond to habitat types, resembling the scenario of inshore-offshore differentiation seen in other populations of the same species in other regions. The analysis also confirmed that there is no evident gene flow between the two “sister species”, the common bottlenose dolphin and the Indo-Pacific bottlenose dolphin (T. aduncus), occurring sympatrically in the region. The mtDNA data suggested that the Risso’s and Fraser’s dolphin populations in the western North Pacific experienced an episode of expansion in the last 10,000 years. Genetic diversity is high in most of the population examined in this study; however, a relatively low effective population size is found in some populations and that may require further conservation attention

Marine invertebrates and sound

Peer ReviewedPostprint (published version

Nutrient Cycling and Plant Nutrition in Forest Ecosystems

Nutrient cycling is essential for maintaining nutrient supply to forest plants and for enhancing forest productivity. Nutrient cycling is also strongly linked to greenhouse gas emissions and thus to global climate change. Nutrient cycling and plant nutrition can be severely affected by anthropogenic and natural disturbance regimes. This Special Issue will provide an avenue to publish recent progress on research on nutrient cycling and plant nutrition in forest ecosystems and how nutrient cycling and plant nutrition are affected by disturbance regimes such as harvesting, atmospheric deposition and climate change

Geo-stategic approaches to co-operative maritime security in northeast Asia : with particular reference to naval arms control, maritime confidence-building measures and maritime co-operation measures

The purpose of this study is to design a co-operative maritime security structure for Northeast Asia through the application of naval arms control and disarmament measures (both structural and operational), maritime confidence-building measures (MCBMs) and maritime cooperation measures (MCMs). In order to construct an analytical framework for such an application it is necessary to introduce sub-objectives. The first is to explore the options for providing co-operative maritime security, such as naval arms control. MCBMs and MCMs, and to assess the value of their contribution to the general co-operative maritime security framework. The second is to examine the particular points of the major regional powers' maritime security policies with a view to considering their relevance to the construction of a system of co-operative maritime security in Northeast Asia. The third is to delineate the regional geo-strategic security environment conducive to Northeast Asian co-operative maritime security in the framework of the various types of measures. The final part examines the potential conditions for the application of co-operative maritime security measures and suggests a priority of application on the basis of the regional maritime security environment.In the last decade, the United States and Russia have been forced to change their defence policies, trim their budgets, curtail operations overseas, and re-evaluate their fundamental purposes. Nonetheless, the medium powers, such as China and Japan, continue to build and deploy naval weapons and vessels that others find threatening. Unless they reconsider their positions toward co-operative maritime security, they may miss a critical opportunity to bring stability to the high seas. In Northeast Asia, the main boundary and territorial disputes are maritime in nature, e.g. Russia-Japan (South Kuril IslandslNorthern Territories), Korea-Japan (the Tok Islandsffakeshima), China-Japan (the Senkaku Islandsffiaoyu Tao), as well as Taiwan and, in the South China Sea, the Paracel Islands/Xisha Qundao (Vietnam-China), and the Spratly IslandslNansha Qundao (China, Vietnam, Malaysia, Taiwan, Philippines and Brunei). Multilateral security activities cannot replace formal diplomatic/legal negotiations to settle maritime boundary and territorial disputes, but co-operative maritime security measures may be particularly valuable in minimising the risk of conflict in such circumstances.Among the MCBMs, the most promising areas involve modifying existing INCSEA agreements, and establishing or expanding measures of transparency, such as compliance with the UN or an eventual regional arms register and the regular issue of credible official Defence White Papers. In the current context of strategic uncertainty and maritime force development in Northeast Asia, information exchange measures and communication measures may be the most valuable MCBM, applicable region-wide. Co-operative maritime security measures can offer a number of benefits. The main goals of MCMs are cost reduction through shared efforts or by joint operations for humanitarian purposes, joint development of marine resources, the protection of SLOCs and prevention of sea pollution. MCMs can also be used as confidence-building measures in themselves to maintain communication when tensions heighten. MCMs indicate that neighbouring countries can work together to look after certain problems at the regional or subregional level. This can help not onJy to deter potential adversaries but also to assure extraregional countries that no direct threat would be posed to their sea-borne trade. With functional and operational approaches, MCMs cover marine pollution, search and rescue, illegal activities, including drug smuggling, piracy and fisheries infringement.The first area of naval arms control to be considered covers constraints on naval activities as operational naval arms control measures. General operational arms control measures could be used to cover other naval activities, or they could serve as a model for similar agreements in other areas. The provisions for notification of dangerous activities, for instance, could be broadened to include mandatory notification of all naval exercises. After the 1972 Incidents at Sea Agreement, the United States and Russia developed stabilising rules of behaviour as their navies came into contact with each other across the world's oceans. With the expansion of naval forces in Northeast Asia and the increased likelihood of accident and miscalculation, one could make a case for the negotiation of regional INCSEA agreements, particularly on a bilateral basis. Such agreements already exist in the North Pacific: Canada and Russia, the US and Russia, Russia-Japan and Russia-ROK. The United States and China have also signed a related agreement on maritime consultation. Operational measures at sea could be implemented by imposing restraints on naval activities and geographical limitations. Structural measures, as the second aspect of naval arms control, consist of quantitative and qualitative approaches. A quantitative approach based on ratios would inevitably affect the relative size of forces of different countries. Such agreements are difficult to achieve because of differences in geostrategic goals and asymmetries of naval forces in the region.This thesis argues that the development of co-operative maritime security measures to the point where they become a significant aspect of the regional maritime security framework in Northeast Asia will not be easy. It is a very diverse region, where there are quite different security perceptions and maritime territorial and legitimacy conflicts which require resolution. There is also little tradition of security co-operation, at least on a multilateral basis. The maritime issues themselves are generally complicated, and the practical and operational factors involved in the establishment of effective co-operative maritime security regimes are extremely demanding. Maritime confidence-building measures offer the greatest potentiaL as an initial step. As subsequent steps, maritime co-operation measures and naval arms control measures could be followed. The important question is whether or not the application of co-operative security models can be brought to the point where they can enable the effective management of the increasing complexities and uncertainties which characterise the emerging maritime environment in Northeast Asia. Current fiscal constraints might clearly provide an opportunity for Northeast Asian countries not only to consider more closely their threat perceptions but also to pursue regional co-operative maritime arrangements which rely more on mutual understanding and less on a naval arms build-up

Identifying key threats and conservation requirements for the Critically Endangered Yangtze finless porpoise

Evidence-based conservation is the most effective way to preserve biodiversity. However, for many species robust long-term data sets are not available and so the process of selecting effective interventions is poorly-informed and at risk of being ineffective. The Critically Endangered Yangtze finless porpoise (Neophocaena asiaeorientalis), a unique freshwater cetacean endemic to the Yangtze River, China, is subject to numerous anthropogenic threats that have led to significant population decline in recent decades. Conservation of this species has been severely limited by a poor understanding of the causes of population decline. By using four novel lines of analysis on already existing data sets, this study firstly assessed whether there is currently a sufficient evidence base to inform conservation of this species. This process established conservation-relevant conclusions and identified key remaining knowledge gaps without having to use valuable resources and time to gather further data. Subsequently, boat-based mapping studies have revealed conservation-relevant spatial and temporal patterns relating to potential threat presence and YFP habitat use on multiple spatial scales, whilst extensive interview-based surveys with fishers have been used to gather detailed information on patterns in illegal fishing gear use and YFP bycatch, as well as conservation-relevant socio-economic data. In addition, longitudinal interview data has provided an invaluable insight into changes in human-wildlife interactions and high-risk human behaviours over time. Lastly, an interview survey with key stakeholders involved in Yangtze finless porpoise conservation has demonstrated that evidence-based conservation is not being applied to this species, meaning that interventions are not targeted to key causes of decline and there is a risk of conservation complacency and extinction of a second Yangtze River cetacean. The multi-disciplinary research presented here has demonstrated how the conservation process for data-poor endangered species can be improved by increasing the knowledge base surrounding potential threats and causes of direct and indirect mortality, which has wider application for other at-risk species