The world’s coastal zones are experiencing rapid development and an increase in storms and flooding. These hazards put coastal communities at heightened risk, which may increase with habitat loss. Here we analyse globally the role and cost effectiveness of coral reefs in risk reduction. Meta-analyses reveal that coral reefs provide substantial protection against natural hazards by reducing wave energy by an average of 97%. Reef crests alone dissipate most of this energy (86%). There are 100 million or more people who may receive risk reduction benefits from reefs or bear hazard mitigation and adaptation costs if reefs are degraded. We show that coral reefs can provide comparable wave attenuation benefits to artificial defences such as breakwaters, and reef defences can be enhanced cost effectively. Reefs face growing threats yet there is opportunity to guide adaptation and hazard mitigation investments towards reef restoration to strengthen this first line of coastal defence.
Restoration of degraded land is recognized by the international community as an important way of enhancing both biodiversity and ecosystem services, but more information is needed about its costs and benefits. In Cambridgeshire, U.K., a long-term initiative to convert drained, intensively farmed arable land to a wetland habitat mosaic is driven by a desire both to prevent biodiversity loss from the nationally important Wicken Fen National Nature Reserve (Wicken Fen NNR) and to increase the provision of ecosystem services. We evaluated the changes in ecosystem service delivery resulting from this land conversion, using a new Toolkit for Ecosystem Service Site-based Assessment (TESSA) to estimate biophysical and monetary values of ecosystem services provided by the restored wetland mosaic compared with the former arable land. Overall results suggest that restoration is associated with a net gain to society as a whole of $199 ha−1y−1, for a one-off investment in restoration of $2320 ha−1. Restoration has led to an estimated loss of arable production of $2040 ha−1y−1, but estimated gains of $671 ha−1y−1 in nature-based recreation, $120 ha−1y−1 from grazing, $48 ha−1y−1 from flood protection, and a reduction in greenhouse gas (GHG) emissions worth an estimated $72 ha−1y−1. Management costs have also declined by an estimated $1325 ha−1y−1. Despite uncertainties associated with all measured values and the conservative assumptions used, we conclude that there was a substantial gain to society as a whole from this land-use conversion. The beneficiaries also changed from local arable farmers under arable production to graziers, countryside users from towns and villages, and the global community, under restoration. We emphasize that the values reported here are not necessarily transferable to other sites.
The present study evaluates the role of marine aquaculture in the conversion of mangrove forests into shrimp (Litopenaeus vannamei, Boone, 1931) farms using remote sensing and geographic information system techniques and analyzes the productivity of the installed farms in the mangroves and adjacent coastal plateau. The extension of the shrimp ponds was quantified using satellite image analysis, and the water quality of the shrimp farms was analyzed based on measurements of dissolved oxygen concentration, temperature, pH, and salinity. The productivity of the farms was measured using biometric data. The data were analyzed using ANOVA with Tukey's post-test. The results indicated that shrimp farms cover an area of ∼0.8 km2 (approximately 0.4% of Brazilian ponds), of which 29.4% are located within areas of mangroves, and 70.6% are located in the coastal plateau. Saltwater aquaculture contributed to the conversion of 0.53 km2 of the mangroves into rearing ponds, which represents only 0.007% of the total area of the Amazonian mangroves. The installations in the mangrove presented significantly higher pH, temperature, transparency, and salinity compared with the ponds installed in the coastal plateau, although coastal plateau ponds had higher dissolved oxygen concentrations. Based on these differences, the mean sizes of the shrimp raised in the mangrove and coastal plateau ponds were 5.7 g and 4.3 g, respectively. However, the estimated value of one hectare of mangrove is much higher than its potential value in the production of shrimp. The considerable value of the ecosystem services provided by the mangroves indicates that the production of shrimp in the coastal plateau is relatively less damaging in ecological and economic terms. Thus, we can consider that the production of shrimp in the coastal plateau instead of in mangrove areas is less damaging to the long-term conservation of mangrove forests, which follows the management best practices established by international organizations. The coastal zone is considered a common resource that belongs to all citizens in Iberoamerican countries, and it is defined as a zone of non-building. Therefore, we conclude that mangroves are more valuable intact than converted into aquaculture ponds. Hence, aquaculture activities in the Amazon coastal plain are not sustainable from environmental and socioeconomic perspectives.
Dredged sediments derived by the low course and estuary of the metropolitan river of Athens (Kifissos River) were dumped every day for 21 months to an open-sea site in the Saronikos Gulf. The spoil-ground and surrounding area was monitored prior, during and post to dumping for 24 months, over 6-month intervals. Dumping significantly changed the granulometry of the pre-existing superficial sediments to finer-grained only in the spoil ground and increased the sediment contamination load (aliphatic, polycyclic aromatic hydrocarbons and heavy metals) throughout the study area. Microtox® SPT showed that sediment toxicity levels were high at almost all sampling stations. During dumping, burial of natural soft-bottom habitats degraded severely the communities of the spoil-ground resulting in an almost azoic state, as well as significantly declined the species number and abundance of benthic communities in locations up to 3.2 km away from the spoil-ground, due to dispersion of the spoil and smothering. Benthic indices on the surrounding sites were significantly correlated with hydrocarbon concentrations and sediment toxicity levels. Post to dumping, the macrofauna communities of the spoil-ground were still significantly degraded, but the surrounding areas showed patterns of recovery. However, the high concentrations of aliphatic, polycyclic aromatic hydrocarbons and levels of toxicity persisted in the sediments after the ceasing of dumping operations in the study area, implying the ecological hazard imposed on the area.
The aim of this study is to predict changes in the distribution and extent of habitat forming species defined as “Priority Marine Habitats” (PMHs) in the North-East (NE) Atlantic under future scenarios of climate-induced environmental change. A Species Distribution Modelling method was used for each PMH to map the potential distribution of “most suitable” habitat. The area and percentage cover was calculated within each country׳s Exclusive Economic Zone for the baseline (2009) and the projected (2100) years. In addition, a conservation management score was calculated based on the number of PMHs that co-occur in assessment units. Overall, this study reveals the potential for movement and/or change in the extent of some PMHs across the NE Atlantic under an increased ocean temperature scenario (4 °C) by 2100. There are regional differences in the predicted changes and some countries will experience greater/different changes than others. The movement of biodiversity hotspots (where one or more PMHs occur in the same broad area) provides both opportunities and risks for conservation management that are discussed. Co-operation between neighbouring countries and marine regions will require substantial enhancement in order to provide a robust adaptive management strategy going forward.
Large-scale extraction of power from tidal streams within the Pentland Firth is expected to be underway in the near future. The Inner Sound of Stroma in particular has attracted significant commercial interest. To understand potential environmental impacts of the installation of a tidal turbine array a case study based upon the Inner Sound is considered. A numerical computational fluid dynamics model, Fluidity, is used to conduct a series of depth-averaged simulations to investigate velocity and bed shear stress changes due to the presence of idealised tidal turbine arrays. The number of turbines is increased from zero to 400. It is found that arrays in excess of 85 turbines have the potential to affect bed shear stress distributions in such a way that the most favourable sites for sediment accumulation migrate from the edges of the Inner Sound towards its centre. Deposits of fine gravel and coarse sand are indicated to occur within arrays of greater than 240 turbines with removal of existing deposits in the shallower channel margins also possible. The effects of the turbine array may be seen several kilometres from the site which has implications not only on sediment accumulation, but also on the benthic fauna.
This paper assesses operational impacts of large-scale ocean wave energy development in the US Pacific Northwest. High-resolution wave power production and forecasting data is synthesized for wave energy arrays spatially-distributed along the region's coast. Geographic diversification is found to limit the rate at which production variability scales with installed capacity, over timescales ranging from minutes to hours. The reduced variability makes it easier to forecast short-term wave generation accurately. When modeled within the operational structure of the region's primary balancing area authority, large-scale wave energy is found to provide a relatively high capacity value and costs less to integrate than equivalent amounts of wind energy.
This paper reports the methodology established in the application of a numerical wave model for hindcasting of wave conditions around the United Kingdom, in particular for Scottish waters, for the purpose of wave energy resource assessment at potential device development sites. The phase averaged MIKE 21 Spectral wave model has been adopted for this study and applied to the North Atlantic region bounded by latitudes 10° N–70° N and longitudes 10° E−75° W. Spatial and temporal wind speeds extracted from the European Centre for Medium Range Weather Forecast (ECMWF) have been utilised to drive the wave model. A rigorous calibration and validation of the model has been carried out by comparing model results with buoy measurements for different time periods and locations around Scotland. Significant wave height, peak wave period and peak wave direction obtained from the model correlated very well with measurements. Spatially varying statistical mean and maximum values of the significant wave height and wave power obtained based on a one-year wave hindcasting are in good agreement with the UK Marine Atlas values. The wave model can be used with high level of confidence for wave hindcasting and even forecasting of various wave parameters and wave power at any desired point locations or for regions. The wave model could also be employed for generating boundary conditions to small scale regional wave and tidal flow models.
In Belize, beginning in 2011 at Glover's Reef Marine Reserve, and in 2012 at Port Honduras Marine Reserve, fishers have been required to keep logbooks to document their catch and effort. A Bayesian depletion model including in-season recruitment was applied to the standardized catch per unit effort (cpue) of Caribbean spiny lobster (Panulirus argus) from the logbooks to estimate the abundance and fishing mortality of lobsters at both sites. Two alternative subsets of the cpue data were used to account for changes in targeting caused by the opening and closing of the queen conch (Strombus gigas) season. At Glover's Reef, a typical model estimated abundance ∼66–79 000 lobsters. Of these, ∼60–85% were present at the beginning of the season and the rest recruited into the fished population later in the season. The depletion model applied to data from the 2012 season at Port Honduras found an abundance of ∼12 000 lobsters, and in-season recruitment was not supported by the data. That in-season recruitment was present at Glover's Reef and not at Port Honduras may be explained by the fact that Glover's Reef has more unfished areas that could serve as a source of adult lobsters during the season. Glover's Reef has a larger no-take zone (20% of the reserve area, compared with 5% at Port Honduras), and it is surrounded by a deep wall reef where lobsters are found below the depth accessible to fishers. The models estimated a harvest fraction of ∼70% in both reserves.
Measuring the success or failure of natural resource management is a key challenge to evaluate the impact of conservation for ecological, economic and social outcomes. Marine reserves are a popular tool for managing coastal ecosystems and resources yet surprisingly few studies have quantified the social-economic impacts of marine reserves on food security despite the critical importance of this outcome for fisheries management in developing countries. Here, I conducted semi-structured household surveys with 113 women heads-of-households to investigate the influence of two old, well-enforced, no-take marine reserves on food security in four coastal fishing communities in Kenya, East Africa. Multi-model information-theoretic inference and matching methods found that marine reserves did not influence household food security, as measured by protein consumption, diet diversity and food coping strategies. Instead, food security was strongly influenced by fishing livelihoods and household wealth: fishing families and wealthier households were more food secure than non-fishing and poorer households. These findings highlight the importance of complex social and economic landscapes of livelihoods, urbanization, power and gender dynamics that can drive the outcomes of marine conservation and management.