Search

The study is part of the 4-year Blue Forests Project, initiated by the United Nations Environment Programme (UNEP) and partly funded by the Global Environment Facility (GEF). We thank the Swedish International development Cooperation Agency—Sida, marine bilateral programme for funding the participation of ROI and LDL. Funding was provided to PM through an Australian Research Council LIEF Project (LE170100219) and by the Generalitat de Catalunya (Grant 2017 SGR-1588). This work is contributing to the ICTA ‘‘Unit of Excellence’’ (MinECo, MDM2015-0552). Funding for MD was provided by the Bolin Centre for Climate Research. AA-O was supported by ‘‘Obra Social la Caixa’’ (LCF/BQ/ES14/10320004) and subsequently by the NOAA C&GC Postdoctoral Fellowship administered by UCAR-CPAESS (#NA18NWS4620043B). The IAEA is grateful for the support provided to its Environment Laboratories by the Government of the Principality of Monaco. Context: Seagrass meadows act as efficient natural carbon sinks by sequestering atmospheric CO2 and through trapping of allochthonous organic material, thereby preserving organic carbon (Corg) in their sediments. Less understood is the influence of landscape configuration and transformation (land-use change) on carbon sequestration dynamics in coastal seascapes across the land–sea interface. Objectives: We explored the influence of landscape configuration and degradation of adjacent mangroves on the dynamics and fate of Corg in seagrass habitats. Methods: Through predictive modelling, we assessed sedimentary Corg content, stocks and source composition in multiple seascapes (km-wide buffer zones) dominated by different seagrass communities in northwest Madagascar. The study area encompassed seagrass meadows adjacent to intact and deforested mangroves. Results: The sedimentary Corg content was influenced by a combination of landscape metrics and inherent habitat plant- and sediment-properties. We found a strong land-to-sea gradient, likely driven by hydrodynamic forces, generating distinct patterns in sedimentary Corg levels in seagrass seascapes. There was higher Corg content and a mangrove signal in seagrass surface sediments closer to the deforested mangrove area, possibly due to an escalated export of Corg from deforested mangrove soils. Seascapes comprising large continuous seagrass meadows had higher sedimentary Corg levels in comparison to more diverse and patchy seascapes. Conclusion: Our results emphasize the benefit to consider the influence of seascape configuration and connectivity to accurately assess Corg content in coastal habitats. Understanding spatial patterns of variability and what is driving the observed patterns is useful for identifying carbon sink hotspots and develop management prioritizations. info:eu-repo/semantics/publishedVersion

The seas of northern Europe are strongly affected by human activities and there is a great need for improved marine conservation. The same region is also the current hotspot for offshore wind power development. Wind farms can have negative environmental impacts during construction, but during the operational phase many organisms are attracted to the foundations and thereby may also find refuge from fisheries. Given the recent implementation of marine spatial planning in Europe and elsewhere, this is a critical time to address potential compatibility and synergies between marine conservation and wind power. This review concludes that offshore wind farms can be at least as effective as existing marine protected areas in terms of creating refuges for benthic habitats, benthos, fish and marine mammals. The degree of advantage for these organisms depends on the location of the wind farm and the level of imposed fishing restriction. Under certain conditions wind farms may even be more efficient means of conservation than ordinary marine protected areas. However, offshore wind farms can be negative for several species of seabirds, essentially as occupying preferred feeding or wintering grounds. In areas important to these seabirds wind farms may not comply with conservation. The results bring important messages to marine spatial planning as some but not all wind farms can be spatially combined with, and even synergistic to, marine conservation.

Offshore wind power is expanding with particular development plans in the Baltic and the North Sea. To reassure an environmentally acceptable development, regulatory authorities need to make informed decisions even when evidence and experience are scarce. In this study Ecological Risk Assessment (ERA) has been applied on a wind farm project in Kattegat, proposed within a spawning ground for the Kattegat cod, a threatened population of Atlantic cod (Gadus morhua L). Six stressors with potential impacts on cod and related to wind farms were investigated. Three of them - extreme noise from pile driving, noise from vessels, and disturbances due to cable-trenching - are related to the construction phase, while lubricant spills and noise from turbines together with electric fields from cables are related to the operation phase. The ecological risk was derived from the combined likelihood and magnitude of potential adverse effects from stressors to the cod population using a weight-of-evidence (WOE) ranking procedure. Available evidence was evaluated based on its reliability, and contradictory arguments were balanced against each other using evidence maps. The option of performing hazardous construction events (e.g. pile-driving) outside biologically sensitive periods was incorporated in the assessment. It was shown that the construction of the wind farm poses a high risk to cod, as defined by the ranked and combined likelihoods and magnitudes of adverse effects. However by avoiding particular construction events during the cod recruitment period ecological risks can be significantly reduced. Specifically for this case, ecological risks are reduced from high to low by avoiding pile-driving from December through June, which confirms previous indications that pile-driving is the most ecologically hazardous activity of offshore wind power development. Additional risk reduction is achieved by avoiding cable trenching from January through May. The study thus illustrates the effectiveness of time-planning for risk reduction. Importantly, the study illustrates how combined ERA and WOE methods can be valuable for handling uncertainties of environmental impacts within offshore industrial development. (C) 2014 Elsevier Ltd. All rights reserved.

Several African countries in the Western Indian Ocean (WIO) endure insufficiencies in the power sector, including both generation and distribution. One important step towards increasing energy security and availability is to intensify the use of renewable energy sources. The access to cost-efficient hydropower is low in coastal and island regions and combinations of different renewable energy sources will play an increasingly important role. In this study the physical preconditions for renewable ocean energy are investigated, considering the specific context of the WIO countries. Global-level resource assessments and oceanographic literature and data have been compiled in an analysis of the match between technology-specific requirements for ocean energy technologies (wave power, ocean thermal energy conversion (OTEC), tidal barrages, tidal current turbines, and ocean current power) and the physical resources in 13 WIO regions Kenya, Seychelles, Northern Tanzania and Zanzibar, Southern Tanzania, Comoros and Mayotte, Northern-, Central-, and Southern Mozambique, Western-, Eastern-, and Southern Madagascar, Reunion, and Mauritius. The results show high potential for wave power over vast coastal stretches in southern parts of the WIO and high potential for OTEC at specific locations in Mozambique, Comoros, Reunion, and Mauritius. The potential for tidal power and ocean current power is more restricted but may be of interest at some locations. The findings are discussed in relation to currently used electricity sources and the potential for solar photovoltaic and wind power. Temporal variations in resource intensity as well as the differences between small-scale and large-scale applications are considered.

A variety of hydrokinetic turbines are currently under development for power generation in rivers, tidal straits and ocean currents. Because some of these turbines are large, with rapidly moving rotor blades, the risk of collision with aquatic animals has been brought to attention. The behavior and fate of animals that approach such large hydrokinetic turbines have not yet been monitored at any detail. In this paper, we conduct a synthesis of the current knowledge and understanding of hydrokinetic turbine collision risks. The outcome is a generic fault tree based probabilistic model suitable for estimating population-level ecological risks. New video-based data on fish behavior in strong currents are provided and models describing fish avoidance behaviors are presented. The findings indicate low risk for small-sized fish. However, at large turbines (≥5 m), bigger fish seem to have high probability of collision, mostly because rotor detection and avoidance is difficult in low visibility. Risks can therefore be substantial for vulnerable populations of large-sized fish, which thrive in strong currents. The suggested collision risk model can be applied to different turbine designs and at a variety of locations as basis for case-specific risk assessments. The structure of the model facilitates successive model validation, refinement and application to other organism groups such as marine mammals.

Hydrokinetic turbines, targeting the kinetic energy of fast-flowing currents, are under development with some turbines already deployed at ocean sites around the world. It remains virtually unknown as to how these technologies affect fish, and rotor collisions have been postulated as a major concern. In this study the effects of a vertical axis hydrokinetic rotor with rotational speeds up to 70 rpm were tested on the swimming patterns of naturally occurring fish in a subtropical tidal channel. Fish movements were recorded with and without the rotor in place. Results showed that no fish collided with the rotor and only a few specimens passed through rotor blades. Overall, fish reduced their movements through the area when the rotor was present. This deterrent effect on fish increased with current speed. Fish that passed the rotor avoided the near-field, about 0.3 m from the rotor for benthic reef fish. Large predatory fish were particularly cautious of the rotor and never moved closer than 1.7 m in current speeds above 0.6 ms(-1). The effects of the rotor differed among taxa and feeding guilds and it is suggested that fish boldness and body shape influenced responses. In conclusion, the tested hydrokinetic turbine rotor proved non-hazardous to fish during the investigated conditions. However, the results indicate that arrays comprising multiple turbines may restrict fish movements, particularly for large species, with possible effects on habitat connectivity if migration routes are exploited. Arrays of the investigated turbine type and comparable systems should therefore be designed with gaps of several metres width to allow large fish to pass through. In combination with further research the insights from this study can be used for guiding the design of hydrokinetic turbine arrays where needed, so preventing ecological impacts.