marine protected areas

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by law or other effective means to protect part or all of .... Enforcement and compliance will be greatly .... FIGURE 1 Map of the Marshall Islands, with locator inset.
Dawson, M. N, and W. M. Hamner. . Rapid evolutionary radiation of marine zooplankton in peripheral environments. Proceedings of the National Academy of Sciences of the USA : –. Dawson, M. N, and W. M. Hamner. . A biophysical perspective on dispersal and the geography of evolution in marine and terrestrial systems. Journal of the Royal Society Interface : –. Donachie, S. et al. . The Hawaiian archipelago: a microbial diversity hotspot. Microbial Ecology : –. Hamner, W. M. . Strange world of Palau’s salt lakes. National Geographic : –. Hamner, W. M., and P. P. Hamner. . Stratified marine lakes of Palau (Western Caroline Islands). Physical Geography : –. Martin, L. E., M. N Dawson, L. J. Bell, and P. L. Colin. . Marine lake ecosystem dynamics illustrate ENSO variation in the tropical western Pacific. Biology Letters : –. Porter, J. S., P. E. J. Dyrynda, J. S. Ryland, and G. R. Carvalho. . Morphological and genetic adaptation to a lagoon environment: a case study in the bryozoan genus Alcyonidium. Marine Biology : –. Tomascik, T., A. J. Mah, A. Nontji, and M. K. Moosa. . The ecology of Indonesian seas. Part I & II. The Ecology of Indonesia Series, Vol. VII. Singapore: Periplus Editions.


Marine protected areas (MPAs) are any intertidal or subtidal areas, together with their associated flora, fauna, and historical and cultural features, that have been set aside by law or other effective means to protect part or all of the designated environments. Marine reserves are a more restrictive subset of MPAs and are defined as areas permanently and completely protected from extractive harvest and other major human uses. MPA PRINCIPLES AND THEORY

As a result of overfishing and overall degradation of marine ecosystems, marine protected areas (MPAs) have increasingly been proposed as an ecosystem-based management tool to conserve biodiversity and manage fisheries. Closing certain areas to harvest for periods of time has been practiced for centuries by Pacific Islanders to help sustain healthy populations of marine resources; area closure has more recently come into increased use because of the failure of more “modern” management methods. By protecting populations, habitats, and ecosystems within their borders, MPAs provide a spatial refuge for the entire ecological system they contain and provide a powerful buffer against human uncertainty

and natural variability. In addition to resource management, MPAs also contribute to the long-term livelihoods of island people though the strong cultural and economic connections between islanders and the sea, as well as their interdependence on a healthy marine environment for survival and prosperity. Theory and experience show that populations of exploited species, when protected within MPAs, respond by producing larger and more abundant individuals (Fig. ). Larger individuals produce exponentially more, and healthier, offspring, and higher population densities improve the likelihood of reproductive success. By increasing reproductive output, MPAs can serve as a source area for larvae that can restock the protected area itself, as well as export larvae to adjacent areas open to fishing. These changes in population structure help to conserve fish stocks within MPA boundaries and provide fisheries benefits outside these protected areas through enhanced reproductive output and adult spillover (Fig. ). Spillover occurs when high population densities within MPAs result in net movement of individuals into nearby areas (Fig. ). This density-dependent emigration can enhance adjacent populations but may also diminish the reproductive potential of the MPA itself if the protected area is too small and the home ranges of the organisms extend out into fished areas where they can be caught. MPAs can protect entire marine ecosystems by conserving multiple species and essential habitats such as spawning areas and nursery grounds. Island ecosystems often contain limited numbers of these critical habitats, which are interconnected by the movement of organisms at a variety of spatial and temporal scales. By protecting 1000 Percent increase within MPA


800 600 400 200 0 Biomass Numbers



FIGURE 1 Species protected inside MPAs have been shown to increase

in total biomass, numbers, size, and diversity over time. Average increases are most pronounced for biomass (413%) and number of individuals (200%). Box plot showing 25th, 50th, and 75th percentiles, with 10th and 90th percentiles as error bars and red bars as means. Adapted from Halpern (2003).


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ecosystem processes necessary for productive populations; () providing a reference point to guide future management decisions; () increasing overall catches despite reducing the fishing area; and () ensuring future catches against management mistakes. Non-Fisheries Benefits

FIGURE 2 Larger-bodied fishes in higher densities within MPAs pro-

duce exponentially more and healthier offspring that can replenish stocks both inside and outside the protected area. Adults and juveniles may spillover from MPAs into adjacent areas as a result of densitydependent effects.


Fish abundance

Partial Reduction


Fished Area

FIGURE 3 Spillover from MPAs to adjacent areas may result from

emigration of fishes from a reserve due to increased competition for resources or other density-dependent mechanisms (black arrows). Shading represents partial reduction in abundance of fishes from inside the MPA that occurs when home ranges extend beyond the MPA boundaries and fish are caught. Adapted from Abesamis et al (2006).

the diversity of habitats and interactions necessary for proper ecosystem function, MPAs represent a holistic ecosystem-based approach to management. BENEFITS OF MPAS Fisheries Benefits

From a fisheries standpoint, MPAs may be used for a number of purposes. Goals include () protecting genetic diversity, size distributions, sex ratios, or other stock characteristics; () reducing bycatch impacts on vulnerable species in multispecies assemblages; () rebuilding overfished stocks; () maintaining habitat characteristics necessary for productive populations; () maintaining 608

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MPAs also have many non-fisheries benefits, such as protecting biodiversity and ecosystem structure, serving as biological reference areas, providing nonconsumptive recreational activities, and maintaining other ecosystem services such as shoreline protection, nutrient cycling, climate control, and so forth. Nonconsumptive access to protected areas includes enhanced economic opportunities, diversified social activities, and increased public awareness. Because of the importance of nearshore ecosystems to islanders, MPAs can also provide a mechanism for cultural maintenance and revival through increased food and economic security. With species loss in the sea accelerating, the irreplaceability of these species makes MPAs a powerful tool for marine conservation by protecting species and their associated habitats. The long-term decline in marine ecosystem health has led to the “shifting baseline syndrome,” where there are no truly natural places left to compare against current conditions. The establishment of MPAs provides an unparalleled opportunity to study marine ecosystems and to better understand ecosystem function in the absence of fishing pressure and other major human impacts. MPA DESIGN CRITERIA

Results suggest that in order to help sustain fisheries, MPAs should cover from  to % of an area, whereas  to % protection may be necessary to ensure high long-term fisheries catch levels. The size and shape of individual MPAs can have important effects on ecological and socioeconomic performance. Individual areas need to be large enough to contain the short-distancedispersing larvae (∼ kilometer) and spaced far enough apart so that long-distance-dispersing larvae (tens to hundreds of kilometers) released from one MPA can settle in adjacent ones. Whether the goals are to enhance fishing or to conserve natural ecosystems, it is desirable to design MPAs so that most adults remain inside whereas some of their reproduction flows out. There is no ideal shape for protecting species and their associated habitats, although swaths stretching from shore into deep water are more likely to contain a diversity of habitats than reserves without as much depth range, and


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Pt. Conception



Santa Barbara






Santa Barbara Channel

Santa Cruz



Santa Rosa



Marine Reserve 33°30'N

1 Marine Conservation Area 2 Marine Conservation Area

Channel Islands National Park


State Waters (Mean High Water to 3 nm) Channel Islands National Marine Sanctuary 0






Marine Protected Areas Network








20 Nautical Miles




Santa Barbara (inset)


FIGURE 4 Example of a network of MPAs varying in size, use, and level of protection. Channel Islands National Marine Sanctuary boundaries

showing the location of existing state and proposed federal marine reserves (no-take) and marine conservation areas that allow limited harvest of lobster and pelagic finfish (1, recreational harvest only; 2, recreational harvest of finfish and both recreational and commercial harvest of lobster). The total MPA network covers about 22% of the sanctuary. Image courtesy of NOAA/Channel Islands National Marine Sanctuary.

they may also encompass common natural migration pathways from shallower nearshore to deeper habitats. Individual MPAs need to be networked in order to provide large-scale ecosystem benefits (Fig. ). An MPA network consists of a series of protected areas that are connected by larval dispersal or juvenile and adult movement. MPA networks have the greatest chance of protecting all species, life stages, and ecological linkages if they encompass representative portions of all ecologically relevant habitat types in a replicated manner. For fisheries purposes, many small reserves in a network may be preferred because of the higher rates of juvenile and adult spillover and more regional benefits through greater larval export than from fewer, larger areas. However, a smaller number of larger MPAs that limit fishing and preserve a greater amount of habitat will provide more benefits for biodiversity conservation. Enforcement and compliance will be greatly aided if reserve borders are straight lines or utilize other obvious navigational reference points. SOCIOECONOMIC FACTORS

The traditional ecological knowledge held by many island peoples is critical to the development and design of MPAs. Traditional customary management systems

have included various forms of area protection, and incorporating elements of these established and recognized practices into a contemporary framework can increase the legitimacy of decisions regarding MPAs, as well as aid in compliance with regulations. Locally managed marine areas that incorporate traditional concepts of customary marine tenure have been effective on many Pacific islands, and participatory community approaches in other parts of the world have also proven to be effective means by which to involve stakeholders in the process, and therefore achieve the intended benefits established for MPAs. SEE ALSO THE FOLLOWING ARTICLES

Fish Stocks/Overfishing / Refugia / Sustainability FURTHER READING

Abesamis, R. A., G. R. Russ, and A. C. Alcala. . Gradients of abundance of fish across no-take marine reserve boundaries: evidence from Philippine coral reefs. Aquatic Conservation: Marine and Freshwater Ecosystems : –. Halpern, B. S. . The impact of marine reserves: do reserves work and does reserve size matter? Ecological Applications : S–S. Palumbi, S. R. . Marine reserves and ocean neighborhoods: the spatial scale of marine populations and their management. Annual Review of Environment and Resources : –.


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Roberts, C. M. . Marine protected areas and biodiversity conservation, in Marine conservation biology: the science of maintaining the sea’s biodiversity. E. Norse and L. Crowder, eds. Washington, DC: Island Press, –. Russ, G. R. . Yet another review of marine reserves as reef fisheries management tools, in Coral reef fishes: dynamics and diversity in a complex ecosystem. P. F. Sale, ed. San Diego, CA: Academic Press, –. Sladek Nowles, J., and A. M. Friedlander. . Marine reserve design and function for fisheries management, in Marine conservation biology: the science of maintaining the sea’s biodiversity. E. Norse and L. Crowder, eds. Washington, DC: Island Press, –.

FIGURE 2 Sandy beach along the ocean shore of Eneu, Bikini atoll.


shrublands, with a relatively limited diversity of plant and animal species. All the atolls and islands are low in elevation. Some of the northern atolls were used for nuclear tests, the impact of which is still being studied.




The loosely strung double archipelagoes of Ratak and R¯alik, with their  atolls and five solitary coral islands, make up what is now known as the Marshall Islands. Marine life associated with these north central Pacific islands is rich and varied. Terrestrial environments range from lush forests and inland mangrove ponds to dry 160˚


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The atolls and islands of the Marshall Islands were formed as marine animals and plants continually built upon the foundation of submerging volcanoes. Sea level was  to . m higher – years ago, during which time the present Marshall Islands were probably just coral reef. After sea level dropped slightly, an estimated  years ago, the atolls became inhabitable. Deep drilling in the Marshall Islands has shown evidence of volcanoes beneath generations of accumulated marine organisms. The Marshalls’ atolls, with their thousand-plus individual islets, are part of the geographical region called “Micronesia” (“small islands”). Total land is now about  km (roughly the area of Santa Catalina Island, California) spread over  million km of ocean, located from °′to °′ N and °′ to °′ E. (Fig. ). Although the land is relatively flat, rarely reaching even  or  m in elevation, marine topography is varied, with seamounts, guyots, and pinnacles scattered across oceanic plains. The narrow, irregularly shaped rings of islets encircling lagoons of the Marshalls’ atolls have many features of classic, idyllic paradises (Figs.  and ). Nevertheless, there are harsh environmental conditions—desiccating winds, salt spray, and an annual dry season. Typhoons are uncommon but are devastating when they occur.










-2250 Depth (m)






FIGURE 1 Map of the Marshall Islands, with locator inset. Satellite

altimetry data: Geoware GMT Companion CD-R Vol. 1, Version 1.9, June 2006. Image prepared by Jenny Paduan and David Clague, MBARI.


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The equatorial countercurrent, equatorial currents, seabirds, and wind continually bring animals and plants. Both above and below water, the biota displays a close relationship with the far western Pacific. Over  fish species and  coral species have been reported; however, there are no native terrestrial mammals, less than three


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