Ecological and environmental variables play a major role in the genetic structure of marine populations, but how oceanography affects their dispersal and associated connectivity remains far from being understood. To account for the effect of different dispersal strategies in terms of pelagic larvae and non-pelagic reproduction, we utilize the power of comparative phylogeographic analyses of five phylogenetically and functionally diverse intertidal species along the west coast of South Africa using population genetics and biophysical models within the Benguela Current system. Some broadcast spawners exhibit genetic panmixia, others show genetic structure similar to direct-developing species, suggesting complex recruitment patterns in rocky shore environments. Patterns of genetic structure do not correspond with pelagic larval competency period, with a broadcast spawning urchin displaying the highest levels of population structure. Biophysical models of larval dispersal reveal mixed dispersal patterns, with the strongest connections in a northward direction following the Benguela Current, yet most modeled species also show the capacity for southward (albeit weaker) migration among some sample localities. Some sites, particularly the most northern areas, show very low levels of potential connectivity. Lastly, we synthesized our results to highlight key areas for the development of Marine Protected Areas (MPAs) that capture the evolutionary patterns of marine species of the west coast and find that the results from our molecular and biophysical analyses are coherent with previous suggestions for a network of protected areas.
Policy formation for the marine environment seems to be a central issue for the maritime nations in order to propose a strategic plan for marine spatial governance. The idea of forming a policy is about understanding the action principle among the institutions involved that guides towards an effective decision making process. The analysis that suits into the reformation of policies is the Institutional Analysis and Development Framework (IAD) that was proposed by Elinor Ostrom, the American political scientist focusing into the institutional behaviours. This paper strives to raise awareness of integrating the concept of Institutional Analysis and Development Framework into the effective practice of Marine Spatial Planning (MSP) in Malaysia. The integration of social science knowledge into the Ecosystem Based Management (EBM) cycles seems to show a growing number in the past decade and the results obtained are reviewed to ensure the suitability of integrating the idea of Institutional Analysis & Development (IAD) into the Malaysian MSP practice to predict institutional behaviour and relationship for the outcomes.
Coastal ecosystems are exposed to multiple anthropogenic stressors such as fishing, pollution, and climate change. Ecosystem-based coastal management requires understanding where the combination of multiple stressors has large cumulative effects and where actions to address impacts are most urgently needed. However, the effects of multiple stressors on coastal and marine ecosystems are often non-linear and interactive. This complexity is not captured by commonly used spatial models for mapping human impacts. Flexible statistical and machine learning models like random forests have thus been used as an alternative modeling approach to identify important stressors and to make spatial predictions of their combined effects. However, tests of such models' prediction skill have been limited. Therefore, we tested how well ten statistical and machine learning methods predicted three ecological indicators of coastal marine ecosystem condition (kelp biodiversity, fish biomass, and rocky intertidal biodiversity) off California, USA. Spatial data representing anthropogenic stressors and ocean uses as well as natural gradients were used as predictors. The models' prediction errors were estimated by double spatial block cross-validation. The best models achieved mean squared errors about 25% lower than a null model for kelp biodiversity and fish biomass; none of the tested models worked well for rocky intertidal biodiversity. The models captured general trends, but not local variability of the indicators. For kelp biodiversity, the best performing method was principal components regression. For fish biomass, the best performing method was boosted regression trees. However, after tuning, this model did not include any interactions between stressors, and ridge regression (a constrained linear model) performed almost as well. While in theory flexible machine learning methods are required to represent the complex stressor-ecosystem state relationships revealed by experimental ecologists, with our data, this flexibility could not be harnessed because more flexible models overfitted due to small sample sizes and low signal-to-noise ratio. The main challenge for harnessing the flexibility of statistical and machine learning methods to link ecological indicators and anthropogenic stressors is obtaining more suitable data. In particular, better data describing the spatial and temporal distribution of human uses and stressors are needed. We conclude by discussing methodological implications for future research.
A growing number of examples indicate that large predators can alter seagrass ecosystem structure and processes via top-down trophic interactions. However, the nature and strength of those interactions varies with biogeographic context, emphasizing the need for region-specific investigations. We investigated spatial and temporal variation in predatory fish and seagrass communities across a Marine Protected Area (MPA) boundary in the Banana River Lagoon, Florida (USA), assessing trophic roles of intermediate consumers, and performing a large-consumer exclusion experiment in the MPA. Large, predatory fishes were most abundant within the MPA, while some mid-sized fishes were more abundant outside it. Small, seagrass-resident fishes, epifaunal invertebrates, and macrophytes also differed across the MPA boundary, but varied more among individual sites and seasonally. We cannot conclusively attribute these patterns to MPA status because we lack data from prior to MPA establishment and lack study replication at the level of MPA. Nevertheless, other patterns among our data are consistent with hypothesized mechanisms of top-down control. E.g., inverse seasonal patterns in the abundance of organisms at adjacent trophic levels, coupled with stable C and N isotope and gut contents data, suggest top-down control of crustacean grazers by seasonal recruitment of small fishes. Large-consumer exclosures in the MPA increased the abundance of mid-sized predatory and omnivorous fishes, but had few impacts on lower trophic levels. Results suggest that large-scale variation in large, predatory fish abundance in this system does not strongly affect seagrass-resident fish, invertebrate, and algal communities, which appear to be driven more by habitat structure and seasonal variation in small fish abundance.
Coastal tourism developed along the Valparaíso region of Chile is being threatened by a very particular issue: scenery degradation related to extreme urbanization and collateral effects. This paper presents the results of scenic evaluation of 96 sites along this region. The scenic evaluation assesses values from a checklist of 18 physical and 8 human parameters, and permits calculation of a scenic evaluation index (D Value), which classifies coastal sites into five classes: Class I, usually natural areas of top scenic characteristics, to Class V, poor scenic natural areas with a higher impact of human interventions. In summary, 14 sites (15%) appeared in Class I; 7 (7%) in Class II; 9 (9%) in Class III; 17 (18%) in Class IV and 49 sites (51%) in Class V. This evaluation provides a complete scenic assessment overview of the Valparaiso Region, allowing implementation of an adequate management strategy based on knowledge of coastal scenery for the maintenance and preservation of scenic quality.
Citizen science observations represent a significant and growing source of species and ecosystem knowledge. These data have potential to support traditional surveys. Databases of citizen observations of wildlife are growing, but how to use this information for scientific purposes is less clear owing to uncertainty in sampling distribution and data quality. In this study, we demonstrate how mapping cetacean patterns using citizen observations and systematic surveys generate consistent and different understandings of cetacean distributions and densities, and evaluate potential risk by assessing cumulative human effects in British Columbia, Canada. We used GIS-based map comparison methods that quantified differences and similarities between geographic datasets to locate where cetacean distributions and densities had spatially unique or spatially analogous representation. Where spatial clusters in both data sources are congruent, we interpret with a higher level of confidence that species occur, and mapped patterns accurately reflect distribution and density. In areas where datasets exhibit dissimilar species densities and distributions, we acknowledge lower confidence and advise further sampling. Regions of agreement were primarily in the central-western portion of the study area (off the southeastern coast of Haida Gwaii); areas of disagreement were heterogeneously distributed across the study area. Spatial clusters from citizen data exhibited significantly higher cumulative human effect scores than from systematic surveys, despite previous data adjustments for human effort. We demonstrate the use of citizen observations as a confirmatory dataset to broaden ecological exploration by augmenting scientific survey datasets and identifying strategic areas for future data collection efforts.Gwaii); areas of disagreement were heterogeneously distributed across the study area. Spatial clusters from citizen data exhibited significantly higher cumulative human effect scores than from systematic surveys, despite previous data adjustments for human effort. We demonstrate the use of citizen observations as a confirmatory dataset to broaden ecological exploration by augmenting scientific survey datasets and identifying strategic areas for future data collection efforts.
The damaging effects of marine debris on wildlife are often noted through the observation of animals that ingest and/or become entangled in debris. Yet, few studies have evaluated the effects of marine litter on benthic habitats. The aim of this study was to investigate if the presence of plastic bags has any effect on benthic macrofauna in an estuary located in an urban area in North-eastern Brazil. Biogeochemical and macrofauna samples were obtained from 10 different deposition locations (location factor), under, border and distant (treatment factor) from plastic bags. The results did not show any significant alterations in the biogeochemical parameters of the sediment due to treatment effect except for summed microphytobenthic pigments. The macrobenthic community structure responded to treatment. The greatest dissimilarity (34%) was between samples that were under and distant. Effects occurred despite the high dynamics of deposition-resuspension of plastic bags and the dominance of opportunistic species. Changes in community structure are a complex result of plastic bags effects on species ecological interactions in the polluted estuarine environment, attracting deposit feeders, diminishing suspension feeders and providing mechanical protection against predation by seabirds.
Mass production of plastics started nearly 70 years ago and the production rate is expected to double over the next two decades. While serving many applications because of their durability, stability and low cost, plastics have deleterious effects on the environment. Plastic is known to release a variety of chemicals during degradation, which has a negative impact on biota. Here, we show that the most commonly used plastics produce two greenhouse gases, methane and ethylene, when exposed to ambient solar radiation. Polyethylene, which is the most produced and discarded synthetic polymer globally, is the most prolific emitter of both gases. We demonstrate that the production of trace gases from virgin low-density polyethylene increase with time, with rates at the end of a 212-day incubation of 5.8 nmol g-1 d-1 of methane, 14.5 nmol g-1 d-1 of ethylene, 3.9 nmol g-1 d-1 of ethane and 9.7 nmol g-1 d-1 of propylene. Environmentally aged plastics incubated in water for at least 152 days also produced hydrocarbon gases. In addition, low-density polyethylene emits these gases when incubated in air at rates ~2 times and ~76 times higher than when incubated in water for methane and ethylene, respectively. Our results show that plastics represent a heretofore unrecognized source of climate-relevant trace gases that are expected to increase as more plastic is produced and accumulated in the environment.
A number of hugely valuable natural resources fall outside of the borders of any nation state. We can legitimately expect political theory to make a contribution to thinking through questions about the future of these extraterritorial resources. However, the debate on the proper allocation of rights over these resources remains relatively embryonic. This paper will bring together what have often been rather scattered discussions of rights over extraterritorial resources. It will first sketch some early modern contributions to thinking through rights over the ocean. It then discusses the guidance available within more contemporary contributions to debates on resources beyond the state. Finally, it concludes by emphasising the key questions with which future work on this topic must engage.
In 2015, the Government of Canada committed to protecting 5% of marine and coastal areas by 2017, and 10% by 2020. While admirable progress towards this target has been made, less attention has been given to improving the quality of protection afforded to marine areas. Extensive scientific study supports that several factors are critical to the success of Marine Protected Areas (MPAs) for marine biodiversity conservation and management objectives, including no-take areas and prohibitions on extractive and industrial activities. However, the majority of Canada’s MPAs allow extractive uses within their boundaries. As Canada works toward international and national commitments to marine protection targets, it is critical to consider the degree of protection afforded by the legal designations used to create these areas. This paper reviews the current inconsistent standards of protection across marine protected areas (MPAs) designated under the Oceans Act, Canada’s flagship legislation for marine protection. Recommended amendments to the law include standards of protection that would exclude all extractive industrial activities from MPAs in order to better guide the designation and decision-making processes for marine protection.