NCEAS working groups have produced marine research of global significance. Here is a sampling of their most influential studies, many of which have informed marine policies and resource management.
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Our research teams have addressed fundamental questions about ecological and evolutionary processes in the ocean.
Many NCEAS studies have explored the ecology of nearshore ecosystems, which provide important services like shoreline protection, water filtration, and critical habitat. Beck et al. (2001) highlighted the importance of habitats like seagrasses, marshes, and mangroves in providing nurseries for a great abundance and diversity of juvenile fish and invertebrates. They developed a novel framework that can be used to identify areas that are important marine nursery grounds, which may inform conservation and management efforts.
The majority of shallow-water marine species have a two-phase life cycle in which relatively sedentary adults produce pelagic larvae that are carried long distances by ocean currents. Since the 1950’s, it has been widely accepted that local populations of marine species are “open,” with new larvae establishing from non-local sources. However, a growing number of studies indicate that larvae are capable of recruiting back to their local source population, known as self-recruitment. One of the most important unanswered questions in marine ecology concerns the degree to which this occurs. Swearer et al. (2002) conducted a review of existing evidence for self-recruitment, and found that it occurs across many species and locations, and may actually be a “pervasive phenomenon” among marine organisms. This highlights a pressing need to re-evaluate the status-quo use of “open” population models in the management of marine ecosystems.
Although we once thought the deep sea to be barren, scientists now understand that this largely unexplored environment is teeming with life. In order to compare the level of biodiversity found in the deep sea with other dissimilar marine habitats, its important to control for geography, taxonomy, habitat structure, and sampling methods, also known as a “controlled comparison.” Here at NCEAS, researchers conducted the first controlled comparison of species diversity on the continental shelf and the deep sea in the Northwest Atlantic region. The results from Levin et al. (2001) support the often-disputed claim that the deep sea actually has considerably higher diversity than exists on the continental shelf.
Threats and Population Declines
Through synthesis-driven status assessments, our research teams have provided insights into threats to and trends in marine species to inform their conservation and management.
Through the synthesis of 47 case studies of seagrass loss, an international team of NCEAS scientists declared seagrass ecosystems to be in a global crisis. Orth et al. (2006) found that coastal development, human population growth, and the resulting increase of nutrient and sediment pollution have contributed to large-scale seagrass losses worldwide. The study’s authors call for targeted global conservation to preserve seagrasses and the essential ecological services that they provide.
Coral reefs have suffered massive declines in abundance, diversity, and habitat structure. However, prior to a 2003 NCEAS study, there was no long-term historical record of ecosystem decline for any coral reef in the world. Through the synthesis of data extending back thousands of years, Pandolfi et al. (2003) reconstructed the ecological histories of 14 coral reef ecosystems. They found that trajectories of decline were strikingly similar worldwide and that all reefs were substantially degraded from overfishing long before recent outbreaks of coral disease and bleaching. Given historical trends, researchers predict that coral reef ecosystems will not survive for more than a few decades unless drastic conservation actions are taken.
NCEAS researchers were involved in producing the most comprehensive assessment of the distribution and conservation status of the world’s mammals, including marine mammals. An NCEAS working group was the starting point for a 5-year collaborative effort coordinated by the International Union for Conservation of Nature in which 1,700 experts from 130 countries compiled detailed information on all 5,487 mammal species. In a landmark Science publication, Schipper et al. (2008) found that threat levels are higher for marine mammals than land mammals, with 36% of marine mammals threatened with extinction. The dominant threat is accidental anthropogenic mortality, particularly in fishing gear and via vessel strike.
Although fisheries bycatch—accidental capture in fishing gear—is often cited as a major driver of sea turtle declines, the magnitude and extent of sea turtle bycatch had not been assessed prior to a study at NCEAS. Lewison et al. (2004) found that worldwide, pelagic longline fisheries were estimated to have accidentally caught at least 200,000 loggerhead turtles and 50,000 leatherback turtles in 2000 alone. This large-scale synthesis was necessary to accurately quantify the effects of global fisheries on these widely distributed, threatened species.
Through the synthesis of paleoecological, archaeological, and historical data, a team of NCEAS scientists was able to trace the recent collapse of coastal ecosystems to long-term trends of overfishing that began thousands of years ago. Jackson et al. (2001) found that historical abundances of large marine vertebrates like whales and sharks were “fantastically large” in comparison to recent observations. Researchers recommend that effective management consider both the current symptoms of ecosystem decline as well as their deep historical causes.
Research at NCEAS has produced the first comprehensive study of how marine life is responding to climate change. Scientists from 17 institutions synthesized all available marine climate impact studies to produce a database of 1,735 observed changes to marine life. Poloczanska et al. (2013) concluded that marine species are moving poleward to cooler waters at an average of 72 kilometers per decade—considerably faster than terrestrial species, which are moving at an average of 6 kilometers per decade. This is occurring even though sea surface temperatures are warming three times slower than land temperatures. The report forms part of the Fifth Assessment Report of the United Nations Intergovernmental Panel for Climate Change (IPCC).
Coastal and Marine Resource Management
Our research teams have evaluated marine resource management strategies to help managers better account for the many ways people use oceans and consider economic and social implications, as well as the ecological ones.
Ecosystem-based management (EBM) aims to restore and protect entire ecosystems for the benefit of all organisms, including humans, by finding a balance between conservation and resource use, often through the valuation of ecosystem services. Contrary to the “all-or-nothing” approach to conservation, Barbier et al. (2008) used EBM to evaluate coastal development for habitats like mangroves and showed that an integrated land use option involving some conversion to shrimp farms and some mangrove preservation may yield the highest total value for coastal communities.
Leveraging the latest marine spatial planning (MSP) tools, scientists at NCEAS have been leaders in developing the theory of marine protected areas (MPAs). Over 50 NCEAS publications have used science to inform the design and implementation of MPAs, in order to optimize their effectiveness for conservation and fisheries management. NCEAS scientists were at the forefront of two important collections of cutting edge marine reserve research: the Ecological Applications Supplement: The Science of Marine Reserves (2003) and the PNAS Marine Reserves Special Feature (2010). All of the publications in the Ecological Applications Supplement and a quarter of the studies featured by PNAS were NCEAS products that integrated marine spatial planning, ecosystem-based management, and MPAs science to provide comprehensive analysis and recommendations.
In one project, Halpern and colleagues were some of the first researchers to go beyond studying marine reserves on an individual basis to explore global trends in how marine life responds to reserve protection. Halpern and Warner (2002) synthesized data from 80 marine reserves and concluded that, overall, there was higher species density, biomass, size, and biodiversity of organisms in marine reserves compared to unprotected areas. They found that marine life responded quickly (1-3 years) to reserve protection and that positive changes last through time.
Measuring and Understanding Ocean Health
Our research teams have developed novel ways to measure and interpret the status of our oceans.
Biodiversity indicators are widely used to assess the state of the world’s oceans and fisheries. However, Branch et al. (2010) determined that the most widely adopted marine biodiversity indicator, which relied upon fish catch data, led to inaccurate conclusions in nearly half of the ecosystems where it was applied. This was the first large-scale test to determine the accuracy of catch data in predicting changes in ecosystem biodiversity. The team recommended greater efforts to measure true abundance trends for multiple marine species, especially those most vulnerable to fishing.
Increasingly ecosystem health is being assessed through the evaluation of ecosystem services; the underlying assumption being that a healthy, productive marine ecosystem provides more services. Worm et al. (2006) found that overall, marine biodiversity loss is increasingly impairing ecosystems, diminishing the ocean's capacity to provide food, maintain water quality, and recover from distress.
The 2015 update to the high-impact 2008 study on global cumulative impact, one of the most highly cited NCEAS papers, developed temporal and spatial analyses of cumulative human impacts on the ocean. Published in Nature Communications, Halpern and colleagues studied the changes in impact caused by climate change, fishing, and ocean- and land- based stressors. They found that two thirds of the ocean has experienced increased impacts from human activity since the initial study, which was predominantly driven by climate change. While the impact of some stressors on the ocean is decreasing, the cumulative impact of all stressors has increased. The 2015 research highlighted which ecosystems should be prioritized for mitigation efforts and serves as an invaluable tool for marine ecosystem management. Learn more about the reserach here.
The Ocean Health Index is a measurement tool that provides a uniform way to evaluate the condition of ecosystems within exclusive economic zones according to 10 human goals that represent the key ecological, social, and economic benefits provided by a healthy ocean. Some of the goals include food provision, coastal protection, and biodiversity. With a perfect health index score being 100, initial results published in Nature by Halpern et al. (2012) revealed that global oceans as a whole earned an overall score of 60. Individually, only 5% of countries scored higher than 70, whereas 32% scored lower than 50. This analysis is repeated yearly to provide resource managers and policy makers with an indicator of progress over time. Lead scientist for the Ocean Health Index, Dr. Ben Halpern, spoke about the project at the first Our Ocean Conference, hosted by the U.S. Department of State in 2014.
The ongoing Ocean Tipping Points project assesses the status of the ocean in the context of ecological thresholds, or “tipping points.” Tipping points exist when small changes in human use or environmental conditions result in large, and sometimes abrupt, impacts to marine ecosystems. Identifying an ecosystem’s vulnerability to tipping points may help managers to anticipate, avoid, or respond to major ecosystem shifts in the ocean.
Available Data in the KNB Repository
In support of open science, NCEAS encourages data publication in online repositories. Below are a few examples of freely available NCEAS datasets pertinent to marine research: