Malin L. Pinsky

Marine defaunation: Animal loss in the global ocean

Marine animals are disappearing, too The loss of animal species in terrestrial environments has been well documented and is continuing. Loss of species in marine environments has been slower than in terrestrial systems, but appears to be increasing rapidly. McCauley et al. review the recent patterns of species decline and loss in marine environments. Though they note many worrying declines, they also highlight approaches that might allow us to prevent the type of massive defaunation that has occurred on land. Science, this issue 10.1126/science.1255641 BACKGROUND Comparing patterns of terrestrial and marine defaunation helps to place human impacts on marine fauna in context and to navigate toward recovery. Defaunation began in earnest tens of thousands of years later in the oceans than it did on land. Although defaunation has been less severe in the oceans than on land, our effects on marine animals are increasing in pace and impact. Humans have caused few complete extinctions in the sea, but we are responsible for many ecological, commercial, and local extinctions. Despite our late start, humans have already powerfully changed virtually all major marine ecosystems. ADVANCES Humans have profoundly decreased the abundance of both large (e.g., whales) and small (e.g., anchovies) marine fauna. Such declines can generate waves of ecological change that travel both up and down marine food webs and can alter ocean ecosystem functioning. Human harvesters have also been a major force of evolutionary change in the oceans and have reshaped the genetic structure of marine animal populations. Climate change threatens to accelerate marine defaunation over the next century. The high mobility of many marine animals offers some increased, though limited, capacity for marine species to respond to climate stress, but it also exposes many species to increased risk from other stressors. Because humans are intensely reliant on ocean ecosystems for food and other ecosystem services, we are deeply affected by all of these forecasted changes. Three lessons emerge when comparing the marine and terrestrial defaunation experiences: (i) today’s low rates of marine extinction may be the prelude to a major extinction pulse, similar to that observed on land during the industrial revolution, as the footprint of human ocean use widens; (ii) effectively slowing ocean defaunation requires both protected areas and careful management of the intervening ocean matrix; and (iii) the terrestrial experience and current trends in ocean use suggest that habitat destruction is likely to become an increasingly dominant threat to ocean wildlife over the next 150 years. OUTLOOK Wildlife populations in the oceans have been badly damaged by human activity. Nevertheless, marine fauna generally are in better condition than terrestrial fauna: Fewer marine animal extinctions have occurred; many geographic ranges have shrunk less; and numerous ocean ecosystems remain more wild than terrestrial ecosystems. Consequently, meaningful rehabilitation of affected marine animal populations remains within the reach of managers. Human dependency on marine wildlife and the linked fate of marine and terrestrial fauna necessitate that we act quickly to slow the advance of marine defaunation. Timeline (log scale) of marine and terrestrial defaunation. The marine defaunation experience is much less advanced, even though humans have been harvesting ocean wildlife for thousands of years. The recent industrialization of this harvest, however, initiated an era of intense marine wildlife declines. If left unmanaged, we predict that marine habitat alteration, along with climate change (colored bar: IPCC warming), will exacerbate marine defaunation. Marine defaunation, or human-caused animal loss in the oceans, emerged forcefully only hundreds of years ago, whereas terrestrial defaunation has been occurring far longer. Though humans have caused few global marine extinctions, we have profoundly affected marine wildlife, altering the functioning and provisioning of services in every ocean. Current ocean trends, coupled with terrestrial defaunation lessons, suggest that marine defaunation rates will rapidly intensify as human use of the oceans industrializes. Though protected areas are a powerful tool to harness ocean productivity, especially when designed with future climate in mind, additional management strategies will be required. Overall, habitat degradation is likely to intensify as a major driver of marine wildlife loss. Proactive intervention can avert a marine defaunation disaster of the magnitude observed on land.

Unexpected patterns of fisheries collapse in the world's oceans

Understanding which species are most vulnerable to human impacts is a prerequisite for designing effective conservation strategies. Surveys of terrestrial species have suggested that large-bodied species and top predators are the most at risk, and it is commonly assumed that such patterns also apply in the ocean. However, there has been no global test of this hypothesis in the sea. We analyzed two fisheries datasets (stock assessments and landings) to determine the life-history traits of species that have suffered dramatic population collapses. Contrary to expectations, our data suggest that up to twice as many fisheries for small, low trophic-level species have collapsed compared with those for large predators. These patterns contrast with those on land, suggesting fundamental differences in the ways that industrial fisheries and land conversion affect natural communities. Even temporary collapses of small, low trophic-level fishes can have ecosystem-wide impacts by reducing food supply to larger fish, seabirds, and marine mammals.

Modeling benefits from nature: using ecosystem services to inform coastal and marine spatial planning

People around the world are looking to marine ecosystems to provide additional benefits to society. As they consider expanding current uses and investing in new ones, new management approaches are needed that will sustain the delivery of the diverse benefits that people want and need. An ecosystem services framework provides metrics for assessing the quantity, quality, and value of benefits obtained from different portfolios of uses. Such a framework has been developed for assessments on land, and is now being developed for application to marine ecosystems. Here, we present marine Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST), a new tool to assess (i.e., map, model, and value) multiple services provided by marine ecosystems. It allows one to estimate changes in a suite of services under different management scenarios and to investigate trade-offs among the scenarios, including implications of drivers like climate. We describe key inputs and outputs of each of the component ecosystem service models and present results from an application to the West Coast of Vancouver Island, British Columbia, Canada. The results demonstrate how marine InVEST can be used to help shape the dialogue and inform decision making in a marine spatial planning context.

Meta-analysis reveals lower genetic diversity in overfished populations

While population declines can drive the loss of genetic diversity under some circumstances, it has been unclear whether this loss is a general consequence of overharvest in highly abundant marine fishes. We compiled data from 11 049 loci across 140 species and found that allelic richness was lower in overfished populations within 9 of 12 genera and families. A multiple linear regression showed that allelic richness was on average 12% lower (P < 0.0001) in overharvested populations after accounting for the effects of body size, latitude and other factors. Heterozygosity was on average 2% lower (P = 0.030). Simulations confirmed that these patterns are consistent with a recent bottleneck in abundant species and also showed that our analysis likely underestimates the loss of rare alleles by a factor of two or three. This evidence suggests that overharvest drives the decay of genetic diversity across a wide range of marine fishes. Such reductions of genetic diversity in some of the worlds most abundant species may lead to a long-term impact of fishing on their evolutionary potential, particularly if abundance remains low and diversity continues to decay.

USING ISOLATION BY DISTANCE AND EFFECTIVE DENSITY TO ESTIMATE DISPERSAL SCALES IN ANEMONEFISH

Robust estimates of dispersal are critical for understanding population dynamics and local adaptation, as well as for successful spatial management. Genetic isolation by distance patterns hold clues to dispersal, but understanding these patterns quantitatively has been complicated by uncertainty in effective density. In this study, we genotyped populations of a coral reef fish (Amphiprion clarkii) at 13 microsatellite loci to uncover fine‐scale isolation by distance patterns in two replicate transects. Temporal changes in allele frequencies between generations suggested that effective densities in these populations are 4–21 adults/km. A separate estimate from census densities suggested that effective densities may be as high as 82–178 adults/km. Applying these effective densities with isolation by distance theory suggested that larval dispersal kernels in A. clarkii had a spread near 11 km (4–27 km). These kernels predicted low fractions of self‐recruitment in continuous habitats, but the same kernels were consistent with previously reported, high self‐recruitment fractions (40–60%) when realistic levels of habitat patchiness were considered. Our results suggested that ecologically relevant larval dispersal can be estimated with widely available genetic methods when effective density is measured carefully through cohort sampling and ecological censuses, and that self‐recruitment studies should be interpreted in light of habitat patchiness.

Climate change's impact on key ecosystem services and the human well-being they support in the US

Climate change alters the functions of ecological systems. As a result, the provision of ecosystem services and the well-being of people that rely on these services are being modified. Climate models portend continued warming and more frequent extreme weather events across the US. Such weather-related disturbances will place a premium on the ecosystem services that people rely on. We discuss some of the observed and anticipated impacts of climate change on ecosystem service provision and livelihoods in the US. We also highlight promising adaptive measures. The challenge will be choosing which adaptive strategies to implement, given limited resources and time. We suggest using dynamic balance sheets or accounts of natural capital and natural assets to prioritize and evaluate national and regional adaptation strategies that involve ecosystem services.

Angling Ecotourism: Issues, Guidelines and Experience from Kamchatka

Recreational fishing is an important component of the tourism industry and an important component of regional economies around the world. When angling tourists reach threatened freshwater ecosystems, however, there is a risk of degrading the very fishery and landscapes that attracted them, thwarting long-term economic development prospects and reducing biodiversity. Following the emergence of catch-and-release recreational fishing, we believe that angling can be legitimately considered a form of ecotourism that contributes positively to conservation, science, and local or regional economic development. With successful angling ecotourism projects, anglers and local populations can become viable constituencies for conservation. We describe the angler-sponsored research programme of the Kamchatka Steelhead Project as one case study where many aspects of a successful ecotourism project were present. We then propose guidelines for future angling ecotourism projects and address opportunities and obstacles to the continued development of angling ecotourism.

Quantifying wave attenuation to inform coastal habitat conservation

Coastal vegetation can protect people and property from erosion and flooding, potentially providing a win-win solution for conservation and development. However, the conditions under which natural habitats provide protection have been controversial, partly because the geomorphic, ecological, and hydrodynamic factors that determine wave attenuation vary greatly among locations, times, and studies. We re-analyzed existing wave attenuation studies in kelp, mangrove, marsh and seagrass habitats and found that much of the variation in wave attenuation can be explained by differences in vegetation characteristics and by the change in bulk drag with flow conditions. We found that vegetation can exert substantial drag on passing waves, but that the bulk drag coefficient declines in flow conditions characterized by high Reynolds numbers. This decline is important because storm conditions are highly turbulent (typical Reynolds numbers are greater than 104), and we lack empirical measurements of bulk drag coefficients from such conditions. Failing to account for the decline can over-estimate wave attenuation in storms by 19% to 1600%. These results suggest that larger habitat areas will need to be set aside for coastal protection than previously thought. Our approach provides predictions for designing practical habitat conservation and restoration plans that also protect humans and property from flooding and erosion.

Observations of internal wave packets propagating along‐shelf in northern Monterey Bay

Internal waves of depression were observed propagating along-shelf and into northern Monterey Bay, California (CA) on the inner shelf. These waves had amplitudes approximately equal to the thermocline depth (∼4 m), and were unstable to shear and mix the thermocline. Isopycnal gradient spectra showed that the wave packets lead to an elevated mean dissipation rate of ɛ = 2.63 × 10−5 m3 s−2 for up to 2 hours after wave passage. The proximity to the surface created strong surface convergences that can actively transport buoyant material, such as plankton, back into the bay. The wave packets were observed regularly over the upwelling season across multiple years suggesting they may have large effects on the documented spatial variation of phytoplankton and larvae on the inner shelf. The timing of the waves suggests they are not formed by tides interacting with bathymetry, but are generated by buoyant plume propagation.

Catching the right wave: evaluating wave energy resources and potential compatibility with existing marine and coastal uses.

Many hope that ocean waves will be a source for clean, safe, reliable and affordable energy, yet wave energy conversion facilities may affect marine ecosystems through a variety of mechanisms, including competition with other human uses. We developed a decision-support tool to assist siting wave energy facilities, which allows the user to balance the need for profitability of the facilities with the need to minimize conflicts with other ocean uses. Our wave energy model quantifies harvestable wave energy and evaluates the net present value (NPV) of a wave energy facility based on a capital investment analysis. The model has a flexible framework and can be easily applied to wave energy projects at local, regional, and global scales. We applied the model and compatibility analysis on the west coast of Vancouver Island, British Columbia, Canada to provide information for ongoing marine spatial planning, including potential wave energy projects. In particular, we conducted a spatial overlap analysis with a variety of existing uses and ecological characteristics, and a quantitative compatibility analysis with commercial fisheries data. We found that wave power and harvestable wave energy gradually increase offshore as wave conditions intensify. However, areas with high economic potential for wave energy facilities were closer to cable landing points because of the cost of bringing energy ashore and thus in nearshore areas that support a number of different human uses. We show that the maximum combined economic benefit from wave energy and other uses is likely to be realized if wave energy facilities are sited in areas that maximize wave energy NPV and minimize conflict with existing ocean uses. Our tools will help decision-makers explore alternative locations for wave energy facilities by mapping expected wave energy NPV and helping to identify sites that provide maximal returns yet avoid spatial competition with existing ocean uses.