Increasing human pressures and global environmental change may severely affect the diversity of species assemblages and associated ecosystem services. Despite the recent interest in phylogenetic and functional diversity, our knowledge on large spatio-temporal patterns of demersal fish diversity sampled by trawling remains still incomplete, notably in the Mediterranean Sea, one of the most threatened marine regions of the world. We investigated large spatio-temporal diversity patterns by analysing a dataset of 19,886 hauls from 10 to 800 m depth performed annually during the last two decades by standardised scientific bottom trawl field surveys across the Mediterranean Sea, within the MEDITS program. A multi-component (eight diversity indices) and multi-scale (local assemblages, biogeographic regions to basins) approach indicates that only the two most traditional components (species richness and evenness) were sufficient to reflect patterns in taxonomic, phylogenetic or functional richness and divergence. We also put into question the use of widely computed indices that allow comparing directly taxonomic, phylogenetic and functional diversity within a unique mathematical framework. In addition, demersal fish assemblages sampled by trawl do not follow a continuous decreasing longitudinal/latitudinal diversity gradients (spatial effects explained up to 70.6% of deviance in regression tree and generalised linear models), for any of the indices and spatial scales analysed. Indeed, at both local and regional scales species richness was relatively high in the Iberian region, Malta, the Eastern Ionian and Aegean seas, meanwhile the Adriatic Sea and Cyprus showed a relatively low level. In contrast, evenness as well as taxonomic, phylogenetic and functional divergences did not show regional hotspots. All studied diversity components remained stable over the last two decades. Overall, our results highlight the need to use complementary diversity indices through different spatial scales when developing conservation strategies and defining delimitations for protected areas.
The impact of mean sea level rise (SLR) on extreme water levels is investigated using a numerical model that covers the entire North Sea, but has its highest spatial resolution in the northern part of the German Bight. A 40-year hindcast covering the period 1970 to 2009 is conducted using observed mean sea level (MSL) changes, tides and atmospheric forcing as boundary conditions. The model reproduces the observed water levels well for this control period. A second 40-year run is then conducted considering the same atmospheric forcing but adding + 0.54 m to the MSL to explore the effects of sea level rise on storm surges in the investigation area. At most locations, the second model run leads to changes in the storm surge water levels that are significantly different from the changes in MSL alone. The largest increases of the order of 15 cm (in addition to the MSL changes) occur in the shallow water areas of the Wadden Sea. These increases in storm surge water levels are caused by nonlinear changes in the tidal constituents which are spatially not coherent. The response of the tidal propagation to SLR is investigated based on the results from a tidal analysis of each individual event. These analyses point to an increase in the M2 amplitude and decrease in the amplitudes of frictional and overtides accompanied by less tidal wave energy dissipation. Attributed effects are changes in phase lags of individual constituents leading to a different tidal modulation, thus additionally increasing tidal water levels. Finally, we estimate how SLR affects return water levels in the northern part of the German Bight, with the result that relevant design water levels increase due to the non-linear relationship between SLR and changes in extremes.
Sociospatial information is critical to marine and coastal ecosystem management. The Hawaii Coastal Uses Mapping Project used a participatory geographic information systems (PGIS) methodology to gather local knowledge regarding the location and intensity of coastal human activities in Hawaii's priority sites for coral reef management. PGIS provided an efficient and effective means of obtaining information in a data-poor context, particularly at a scale and location where considerable local knowledge is held by community members and resource users. We detail the PGIS methods developed to collect sociospatial data on human uses in the project regions and discuss important considerations regarding the practice of PGIS that emerged from the mapping process, as well as implications for the production and documentation of spatial knowledge. Key themes include: issues of scale and appropriateness in using PGIS as a method for mapping human coastal and marine activities; data validity, authority, and the nature of local knowledge; community trust, engagement, and collaboration; and utility for coral reef management. While several factors limit local agencies' ability to use this spatial information to date, natural resource managers found the participatory mapping process to be highly valuable for stakeholder identification and engagement, and the maps provide a resource to state and federal managers to better understand the human implications of future management scenarios.
Agencies in the US with oversight for marine renewable energy development idealistically have sought space where this new use might proceed unhindered by other uses. Despite experiential evidence of spatial overlap among existing ocean uses, a lack of documentation made the identification of potential space-use conflicts, communication between existing and potential ocean users, and the design of mitigation exceedingly challenging.
We conducted a study along the US Atlantic and Pacific coasts to gather and document available spatial information on existing use through a compilation and organization of geographic information system (GIS) data. Stakeholder group meetings were used to vet the collected spatial data, and ethnographic interviews were conducted to gather knowledge and cultural perspectives. Results show extensive coverage and overlap of existing ocean space uses and provide a visualization of the social and cultural landscape of the ocean that managers can use to determine which stakeholders to engage.
Marine resource managers are encouraged to recognize that marine space use is dynamic and multi-dimensional and as such research thereof requires a balance between the efficiency of GIS and the stories captured and told by ethnographic research. There are important linkages within and across fisheries and other uses, communities and interests, and across the land–sea interface. Therefore, it is important to use techniques demonstrated in this research that (1) integrate ethnographic and geospatial data collection and analysis; (2) engage stakeholders throughout the process; and (3) recognize the unique qualities of each geographic location and user group to support sound decision-making.
This paper integrates institutional theories of the commons with insights from geography and human behavioral ecology to explore the spatial and temporal dynamics of artisanal fishing in Ecuador's coastal mangrove swamps. The focus is on the cockle fishery commons characterized by a mixture of formal institutional arrangements and an informal division of fishing space that partially influences fisher decisions about where and when to fish. Individual decisions are further explained to a certain degree by the patch choice model since fishers often move on to new grounds when their catch rates fall below average. These optimizing strategies requiring rotation within a socially produced fishing space may contribute to resource renewal, perceived reliable returns for individuals, and a relative stability in fishing effort, potentially mitigating against resource depletion in open-access areas not managed as a common property regime. This study of the interaction between shellfish harvesters, cultural institutions, and the environment contributes to a spatially explicit theory of the commons and points to the crucial role of resource user mobility and dynamic cultural institutions for the ecological sustainability of shellfish fisheries. A better understanding of feedback between individual decision-making and the self-organization of a social-ecological system has critical implications for policy design and fisheries management at similar scales.
The concept of place attachment has been studied extensively across multiple disciplines but only recently with empirical measurement using public participation GIS (PPGIS) and related crowd-sourcing mapping methods. This research trialed a spatially explicit method for identifying place attachment in a regional study in South Australia. Our research objectives were to (1) analyze and present the spatial results of the mapping method as a benchmark for future research, (2) compare mapped place attachment to the more common practice of mapping landscape values in PPGIS that comprise a values home range, (3) identify how participant socio-demographic and home location attributes influence place attachment, (4) provide some guidance for mapping place attachment in future research. We found large spatial variability in individual place attachment and mapped landscape values using both area and distance-based measures. The area of place attachment is influenced by occupational roles such as farming or conservation, as well as home location, especially in coastal versus non-coastal contexts. The spatial distribution of mapped landscape values or values home range is related to, but not identical to mapped place attachment with just over half of landscape values located outside the area of mapped place attachment. Economic livelihood values, as an indicator of place dependence, and social values, as an indicator of place identity, are more likely to be mapped within the place attachment area. Aggregated place attachment across participants in the region showed similar spatial intensity to aggregated values home range, but area-based assessment of place attachment and values home range are distorted by edge effects such as a coastline. To further develop the mapping of place attachment in PPGIS, we identify knowledge gaps from our study and offer suggestions for future research design.
At the world scale, many exploited species are currently threatened or undermined by human activities, particularly fishing. Given this situation, establishing artificial habitats (AHs) and marine protected areas (MPAs) is seen as a way of both conserving biodiversity and managing fishing activities. AHs have two main effects: (1) they attract fish from the surrounding areas and concentrate them in the AH, and (2) they increase the capacity of the environment, as a result of the installation of new individuals or, in some cases, of new species. MPAs decrease fish accessibility by constraining the spatial distribution of the fishing effort. We have developed a system of ordinary differential equations (ODEs) that can be used to describe the evolution of fish density, fishing effort, and landings depending on whether AHs are deployed in a MPA or in a fishing area. The analytical study of the ODE system is simplified by means of assuming that processes occur on different time scales. Fish reproduction and landings were assumed to occur at a “slow” time scale, whereas, fish displacement was assumed to occur at a “fast” time scale. For both scenarios of AHs implementation (in an MPA or in a fishing area), we show the existence of different equilibria according to hypotheses based on a purely attractive or purely productive effect of the AH. In all cases, the deployment of AHs in the fishing area leads to an equilibrium with lower fish biomass and lower fish landings than when AHs are deployed within the MPA. This suggests that AHs should not be fished in order to maximize long term fish productivity and fish landings in the surrounding areas. In addition, we attempt to establish a correspondence between our theoretical results and the management plan for artisanal fisheries on the Senegalese coast, which includes the implementation of both AHs and MPAs. This suggests that there is not enough coordination between the non-governmental organizations deploying the AHs and the institutions managing MPAs. Indeed, AHs are usually either immersed in an MPA or subject to local fishing ban, but in fact regulation is inadequate. In this context, the deployment of AHs as part of fisheries management would be premature and could have potentially adverse effects on the resource.
A large percentage of the world’s population is concentrated along the coastal zones. These environmentally sensitive areas are under intense pressure from natural processes such as erosion, accretion and natural disasters as well as anthropogenic processes such as urban growth, resource development and pollution. These threats have made the coastal zone a priority for coastline monitoring programs and sustainable coastal management. This research utilizes integrated techniques of remote sensing and geographic information system (GIS) to monitor coastline changes from 1989 to 2010 at Hatiya Island, Bangladesh. In this study, satellite images from Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) were used to quantify the spatio-temporal changes that took place in the coastal zone of Hatiya Island during the specified period. The modified normalized difference water index (MNDWI) algorithm was applied to TM (1989 and 2010) and ETM (2000) images to discriminate the land–water interface and the on-screen digitizing approach was used over the MNDWI images of 1989, 2000 and 2010 for coastline extraction. Afterwards, the extent of changes in the coastline was estimated through overlaying the digitized maps of Hatiya Island of all three years. Coastline positions were highlighted to infer the erosion/accretion sectors along the coast, and the coastline changes were calculated. The results showed that erosion was severe in the northern and western parts of the island, whereas the southern and eastern parts of the island gained land through sedimentation. Over the study period (1989–2010), this offshore island witnessed the erosion of 6476 hectares. In contrast it experienced an accretion of 9916 hectares. These erosion and accretion processes played an active role in the changes of coastline during the study period.
No-take marine reserves (NTMRs) are increasingly being established to conserve or restore biodiversity and to enhance the sustainability of fisheries. Although effectively designed and protected NTMR networks can yield conservation and fishery benefits, reserve effects often fail to manifest in systems where there are high levels of non-compliance by fishers (poaching). Obtaining reliable estimates of NTMR non-compliance can be expensive and logistically challenging, particularly in areas with limited or non-existent resources for conducting surveillance and enforcement. Here we assess the utility of density estimates and re-accumulation rates of derelict (lost and abandoned) fishing line as a proxy for fishing effort and NTMR non-compliance on fringing coral reefs in three island groups of the Great Barrier Reef Marine Park (GBRMP), Australia. Densities of derelict fishing line were consistently lower on reefs within old (>20 year) NTMRs than on non-NTMR reefs (significantly in the Palm and Whitsunday Islands), whereas line densities did not differ significantly between reefs in new NTMRs (5 years of protection) and non-NTMR reefs. A manipulative experiment in which derelict fishing lines were removed from a subset of the monitoring sites demonstrated that lines re-accumulated on NTMR reefs at approximately one third (32.4%) of the rate observed on non-NTMR reefs over a thirty-two month period. Although these inshore NTMRs have long been considered some of the best protected within the GBRMP, evidence presented here suggests that the level of non-compliance with NTMR regulations is higher than previously assumed.
Coastal resources are coming under increasing pressure from competition between recreational, commercial and conservation uses. This is particularly so in coastal areas adjacent to major population centres. Given high recreational and conservation values in such areas, economic activities need to be highly efficient in order to persist. Management of these industries must therefore also encourage efficient production and full utilisation of the areas available. In order to achieve this, managers must first understand the level and drivers of productivity, and how these can be influenced. In this study, by way of illustration, the focus was on the Sydney rock oyster industry within Queensland's Moreton Bay, a multiple use marine park with high recreational and conservation value adjacent to Australia’s third largest city. Productivity of the oyster industry in Moreton Bay is currently low compared to historic levels, and management has an objective of reversing this trend. It is unclear whether this difference is due to oyster farmers’ business choices and personal characteristics or whether varying environmental conditions in the Moreton Bay limit the capacity of the oyster industry. These require different management responses in order to enhance productivity. The study examined different productivity measures of the oyster industry using data envelopment analysis (DEA) to determine where productivity gains can be made and by how much. The findings suggest that the industry is operating at a high level of capacity utilisation, but a low level of efficiency. The results also suggest that both demographic and environmental conditions affect technical efficiency in the Bay, with water characteristics improvements and appropriate training potentially providing the greatest benefits to the industry. Methods used in this study are transferable to other industries and provide a means by which coastal aquaculture may be managed to ensure it remains competitive with other uses of coastal resources.