Human-dominated marine ecosystems are experiencing accelerating loss of populations and species, with largely unknown consequences. We analyzed local experiments, long-term regional time series, and global fisheries data to test how biodiversity loss affects marine ecosystem services across temporal and spatial scales. Overall, rates of resource collapse increased and recovery potential, stability, and water quality decreased exponentially with declining diversity. Restoration of biodiversity, in contrast, increased productivity fourfold and decreased variability by 21%, on average. We conclude that marine biodiversity loss is increasingly impairing the ocean's capacity to provide food, maintain water quality, and recover from perturbations. Yet available data suggest that at this point, these trends are still reversible.

/pdf/impacts-of-biodiversity-loss-on-ocean-ecosystem-services-qmsjv5bz0j.pdf

Impacts of biodiversity loss on ocean ecosystem services.

We show that globally declining fisheries catch trends cannot be explained by random processes and are consistent with declining stock abundance trends. Future projections are inherently uncertain but may provide a benchmark against which to assess the effectiveness of conservation measures. Marine reserves and fisheries closures are among those measures and can be equally effective in tropical and temperate areas—but must be combined with catch-, effort-, and gear restrictions to meet global conservation objectives.

https://science.sciencemag.org/content/sci/316/5829/1285.4.full.pdf

Response to Comments on "Impacts of Biodiversity Loss on Ocean Ecosystem Services"

Coastal tourism started in the 19th Century and has increased in non-linear fashion ever since, stimulated by a combination of developments in transport technology and rising prosperity. Initially, mainly national in character, the introduction of roll-on, roll-off ferries and inexpensive air transport caused an exponential 28-fold rise in international tourism between 1950 and the start of the 21st Century. This review considers the impact of tourism at two levels: (1) that created by the sheer numbers of tourists and their demands (‘mass tourism and transport’) and (2) that resulting from individual, often novel, forms of transport (‘personal leisure transport’). Under (1), the consequences of the construction of coastal resorts and roads, marinas and jetties for habitat fragmentation and reduced biodiversity are described. Next, the effects of large cruise ships (now some 250 in number) are considered, particularly in relation to unregulated pollution and the delivery of substantial numbers of tourists to remote destinations. Thirdly, the literature related to disturbance caused by intertidal trampling by tourists on rocky/sandy shores is reviewed, followed by a section devoted to the unappreciated effects of beach ‘cleaning’ (i.e. removal of natural strandlines as well as litter) that is practiced throughout the world’s sandy beach resorts. Finally, the potentially positive area of coastal ecotourism is considered, but evidence is assembled to highlight the problems associated with too high a demand. Under (2), the impact of a range of personal leisure transport modes is considered. These range from relatively innocuous pursuits (e.g. swimming, surfing, sailboarding and dinghy sailing), to an extremely popular sport (SCUBA diving) that is marketed for its environmentally-friendly nature, yet causes measurable deterioration in the world’s coral ecosystems despite good management practices. The impact of motorboats is considered, particularly in the context of transmission of non-native species, while the highly polluting and disturbing technology of ‘personal watercraft’ is evaluated. Finally, the uncontrolled emergence of new ‘extreme sports’ (e.g. ‘coasteering’, kitesurfing) is identified as a future problem. 2005 Elsevier Ltd. All rights reserved.

The impact of tourism and personal leisure transport on coastal environments: A review

A hierarchical sampling design, spanning five orders of magnitude (from 10s of metres to 100s of kilometres) was created in order to quantify the multi-scale spatial variability of visually censused rocky reef fish assemblages in the western Mediterranean Sea. Specifically, we tested the hypotheses that species abundance and the biomass of reef fish populations is higher within than outside marine reserves, and that a north-to-south geographical gradient of these variables exists. We also explored the relationship between the fish assemblage and habitat structure, as an environmental factor likely to account for an important part of the observed variability. The mixed analyses of variance revealed that total abundance and biomass, species richness and abundance and biomass of several target species reached higher average values within marine reserves. Nevertheless, some non-protected localities (e.g. Aguilas) harboured richer and more abundant fish assemblages than some marine reserves. In addition, regional variation, attributable to differences in local carrying capacity and hydroclimatic conditions, are also shown across the studied area. Moreover, the studied assemblage is patchy at small and/or intermediate spatial scales, considering both assemblage descriptors (total abundance and biomass, species richness), and the abundance and biomass of fish species and spatial categories. Detected patterns were different depending on the species and assemblage variables analysed. Differences in habitat structure account for a significant proportion of total variability of the studied variables, and are likely to be responsible for a large part of the observed differences, especially at small-to-intermediate spatial scales. Other factors—spatial variability in larval distribution, settlement and/or post-settlement survival–are discussed in order to explain the observed differences. We concluded that causes of the observed patchiness of Mediterranean reef fish assemblages are probably multiple. Long-term, multi-scale spatial and temporal monitoring actions, as well as process-oriented manipulative experiments are urgently needed in order to ascertain the relative importance of each factor.

Multi-scale spatial heterogeneity, habitat structure, and the effect of marine reserves on Western Mediterranean rocky reef fish assemblages

With marine biodiversity conservation the primary goal for reserve planning initiatives, a site's conservation potential is typically evaluated on the basis of the biological and physical features it contains. By comparison, socio-economic information is seldom a formal consideration of the reserve system design problem and generally limited to an assessment of threats, vulnerability or compatibility with surrounding uses. This is perhaps surprising given broad recognition that the success of reserve establishment is highly dependent on widespread stakeholder and community support. Using information on the spatial distribution and intensity of commercial rock lobster catch in South Australia, we demonstrate the capacity of mathematical reserve selection procedures to integrate socio-economic and biophysical information for marine reserve system design. Analyses of trade-offs highlight the opportunities to design representative, efficient and practical marine reserve systems that minimise potential loss to commercial users. We found that the objective of minimising the areal extent of the reserve system was barely compromised by incorporating economic design constraints. With a small increase in area (<3%) and boundary length (<10%), the economic impact of marine reserves on the commercial rock lobster fishery was reduced by more than a third. We considered also how a reserve planner might prioritise conservation areas using information on a planning units selection frequency. We found that selection frequencies alone were not a reliable guide for the selection of marine reserve systems, but could be used with approaches such as summed irreplaceability to direct conservation effort for efficient marine reserve design.

Efficiency, costs and trade-offs in marine reserve system design

Summary Marine protected areas (MPAs) may be important for protecting the marine environment, but they may also have substantial socio-cultural impacts about which very little is currently known, or acknowledged. In the Mediterranean, few data are available on the socioeconomic consequences of MPAs. The present study reviews the existing data on MPAs in Spain, France, Italy and Greece. A general increase in tourist activities in Mediterranean MPAs is evident, as are increases in the abundances of larger fish species, although there are no data indicating yields for fisheries increase adjacent to MPAs. A large increase in the number of divers and vessels using MPAs has already had impacts on natural benthic communities as a result of diver damage, mooring and the feeding of large fish by divers. Emphasis has been given in only a few MPAs to promoting public awareness of these impacts. Although the conservation of nature should be considered the fundamental objective of MPAs, neglecting their social, cultural and economic impacts has at times led to poor local consensus, if not hostility. We believe that planning and managing MPAs should be conducted on a multidisciplinary basis. Nonetheless, no single model can be considered valid for the whole Mediterranean. The very variable characteristics of coastal areas, from those of small uninhabited islands to those of cities, require different weightings to be assigned for each factor in order to achieve a durable equilibrium and realize the original objectives of each MPA. Only with such flexibility of management will it be possible to reach a greater understanding of the MPA system and create a lasting consensus in favour of conservation, a consensus which would mean an overwhelming majority of people actively avoiding damaging nature and preventing others from doing so.

/pdf/cultural-and-socio-economic-impacts-of-mediterranean-marine-wxc8ggxxku.pdf

J. Mas

Papers

Cultural and socio-economic impacts of Mediterranean marine protected areas