Marine Protected Areas, An Introduction
Dr. Kelli Anderson
Marine protected areas (MPAs) are often employed to restore or conserve a particular species, a habitat, or entire ecosystem. The most recent scientific literature suggests that MPAs can make marine ecosystems more resilient, which may prove to be crucial in an ocean under pressure from climate change, over fishing and marine debris. Besides pure conservation, the goal may be to enhance local fisheries and tourism, preserve an area of cultural or historical significance, or support coastal communities (particularly in developing countries). In this article I’m going to explain some of the design elements that contribute to the success or failure of MPAs, and focus on some of the ecological benefits of MPAs by sharing some success stories. But first, let’s have a look at what the MPA classification actually means.
For many, the terminology of protected areas can be quite confusing. The International Union for Conservation of Nature (IUCN) defines a protected area as “a clearly defined geographical space, recognised, dedicated and managed, through legal or other effective means, to achieve the long-term conservation of nature with associated ecosystem services and cultural values”. This seems pretty open, and in fact MPAs or sections within them may be categorised as marine sanctuaries, no-take zones, critical habitat areas, whale sanctuaries, multiple use areas, buffer zones, marine parks or marine reserves (and the list goes on). The degree of protection provided will depend on the overall goal of the MPA, for example a zone may be afforded full protection (no-take) which includes a ban on fishing and all other extractive activities (such as mining) to preserve entire ecosystems. Whereas certain types of fishing may be banned or fishing may only be allowed during certain months of the year if the aim is to protect a single vulnerable/over exploited species. In any case, all sub-categories are not created equal, and it would be incorrect to assume that an area/species has adequate protection solely because it is within a marine protected area. To see an example relevant to grey nurse sharks head over to this page.
Under certain circumstances positive conservation outcomes can be reached in MPAs that allow some fishing, however there is growing evidence to suggest that no-take zones are more effective at improving biomass, species richness, organism density and average organism size. But what else contributes to the success or failure of MPAs? The first variable that springs to mind for most people is the level of monitoring and enforcement. If MPAs are not policed effectively then they may be next to worthless, and consequently the actual amount of area that is protected will be overestimated on paper. Other important factors that work together synergistically to affect ecosystem health are total MPA size, positioning, habitat diversity, area use adjacent to the MPA, and connectivity to nearby MPAs (in MPA networks).
Marine protected areas (MPAs) are often employed to restore or conserve a particular species, a habitat, or entire ecosystem. The most recent scientific literature suggests that MPAs can make marine ecosystems more resilient, which may prove to be crucial in an ocean under pressure from climate change, over fishing and marine debris. Besides pure conservation, the goal may be to enhance local fisheries and tourism, preserve an area of cultural or historical significance, or support coastal communities (particularly in developing countries). In this article I’m going to explain some of the design elements that contribute to the success or failure of MPAs, and focus on some of the ecological benefits of MPAs by sharing some success stories. But first, let’s have a look at what the MPA classification actually means.
For many, the terminology of protected areas can be quite confusing. The International Union for Conservation of Nature (IUCN) defines a protected area as “a clearly defined geographical space, recognised, dedicated and managed, through legal or other effective means, to achieve the long-term conservation of nature with associated ecosystem services and cultural values”. This seems pretty open, and in fact MPAs or sections within them may be categorised as marine sanctuaries, no-take zones, critical habitat areas, whale sanctuaries, multiple use areas, buffer zones, marine parks or marine reserves (and the list goes on). The degree of protection provided will depend on the overall goal of the MPA, for example a zone may be afforded full protection (no-take) which includes a ban on fishing and all other extractive activities (such as mining) to preserve entire ecosystems. Whereas certain types of fishing may be banned or fishing may only be allowed during certain months of the year if the aim is to protect a single vulnerable/over exploited species. In any case, all sub-categories are not created equal, and it would be incorrect to assume that an area/species has adequate protection solely because it is within a marine protected area. To see an example relevant to grey nurse sharks head over to this page.
Under certain circumstances positive conservation outcomes can be reached in MPAs that allow some fishing, however there is growing evidence to suggest that no-take zones are more effective at improving biomass, species richness, organism density and average organism size. But what else contributes to the success or failure of MPAs? The first variable that springs to mind for most people is the level of monitoring and enforcement. If MPAs are not policed effectively then they may be next to worthless, and consequently the actual amount of area that is protected will be overestimated on paper. Other important factors that work together synergistically to affect ecosystem health are total MPA size, positioning, habitat diversity, area use adjacent to the MPA, and connectivity to nearby MPAs (in MPA networks).
Endangered humphead wrasse, Paul Edward Duckett Photography
Room for Improvement
In order to promote recovery of the vaquita, a small porpoise endemic to the northern Gulf of California (Mexico), a ‘Biosphere Reserve’ was created that prohibited fishing methods known to entangle and kill the species. When the Biosphere Reserve was implemented in 1993, the conservation status of the vaquita was endangered, but just three years later it was upgraded to critically endangered indicating that protective measures had failed. At the heart of the problem was poor positioning of the reserve, as it only covered around 40% of the ~2200 km2 known to be the ‘core’ habitat of the species. Because the vaquita has such a small and well known distribution, this is one case where a correctly designed and managed MPA could have brought the species back from the brink (hopefully it's not too late). Even in the present day (January 2013), the overall population size of this species is still declining according to the IUCN.
Success stories
The Caribbean reef shark is ‘near threatened’ and its overall population trend is listed as ‘declining’ (IUCN). In order to assess whether Glover’s Reef Marine Reserve, a no-take reserve in Belize, was a safe-haven for the shark, scientists set out to measure shark abundance within the reserve and in two other reefs where fishing was still allowed. Baited remote underwater video (BRUV) surveys showed that presence of the marine reserve had a significant positive effect on the number of sharks sighted. Acoustic tagging of the sharks revealed a high tendency for site fidelity, the degree to which an animal repeatedly returns to the same site. A good level of protection and high site fidelity appear to be a good combination for the species, and this is a prime example of what marine reserves are able to achieve. However, as the success of the marine reserve is likely to depend on the sharks spending much of their time within a relatively small area, extensive planning must take place when a migratory species requires protection. In this case a carefully managed network of marine reserves that span a large area (and may cross political borders) may be more appropriate.
No-take marine reserves are expected to enhance ecosystem health within the protected area, but have also been known to have a positive effect outside of reserve boundaries. This can happen in two ways: ‘spillover’ is the process where fish or other organisms move from an area with protection to an area without, and ‘seeding’ occurs when larvae (a very early form of the animal) travel on currents into unprotected areas where they establish themselves and grow. Excellent examples of MPA success have been recorded in the Philippines, were the implementation of no-take reserves adjacent to Sumilon and Apo Islands have resulted in an increase of large predatory fish species richness by four and eleven-fold over fourteen and twenty-five years respectively. After twenty-six years of protection, species richness outside (but close to) the no-take zone increased and became very similar to the level observed within the MPA. Even though some vulnerable species can recover in a relatively short amount of time, it is important that conservation goals are long term, especially for late-maturing species that have a low level of fecundity (have a small number of offspring).
When a well designed and managed MPA exists it can do two things. Firstly ecosystem health can improve which makes the system more robust, and improves the likelihood of withstanding disturbances such as disease or climate change. Secondly, if some kind of damage does occur (from cyclones, coral bleaching etc) the system may recover at a faster rate. In the Exuma Cays (Bahamas), a bleaching and subsequent hurricane event left coral reef ecosystems damaged with an average coral cover of just 7%. Over a 2.5 year period, surveys revealed that coral cover increased to an average of ~19% within marine reserves, while sites outside the reserve showed no net recovery. Recovery within the reserve was apparently linked to changes in macroalgae cover, with lower algae levels allowing coral to grow and recover. Within reserve sites, higher numbers of herbivorous parrotfish that feed on algae are typically found. This suggests that fishing pressure outside reserve boundaries may indirectly increase algae cover and reduce the health of corals in what’s known as a trophic cascade.
No-take marine reserves are expected to enhance ecosystem health within the protected area, but have also been known to have a positive effect outside of reserve boundaries. This can happen in two ways: ‘spillover’ is the process where fish or other organisms move from an area with protection to an area without, and ‘seeding’ occurs when larvae (a very early form of the animal) travel on currents into unprotected areas where they establish themselves and grow. Excellent examples of MPA success have been recorded in the Philippines, were the implementation of no-take reserves adjacent to Sumilon and Apo Islands have resulted in an increase of large predatory fish species richness by four and eleven-fold over fourteen and twenty-five years respectively. After twenty-six years of protection, species richness outside (but close to) the no-take zone increased and became very similar to the level observed within the MPA. Even though some vulnerable species can recover in a relatively short amount of time, it is important that conservation goals are long term, especially for late-maturing species that have a low level of fecundity (have a small number of offspring).
When a well designed and managed MPA exists it can do two things. Firstly ecosystem health can improve which makes the system more robust, and improves the likelihood of withstanding disturbances such as disease or climate change. Secondly, if some kind of damage does occur (from cyclones, coral bleaching etc) the system may recover at a faster rate. In the Exuma Cays (Bahamas), a bleaching and subsequent hurricane event left coral reef ecosystems damaged with an average coral cover of just 7%. Over a 2.5 year period, surveys revealed that coral cover increased to an average of ~19% within marine reserves, while sites outside the reserve showed no net recovery. Recovery within the reserve was apparently linked to changes in macroalgae cover, with lower algae levels allowing coral to grow and recover. Within reserve sites, higher numbers of herbivorous parrotfish that feed on algae are typically found. This suggests that fishing pressure outside reserve boundaries may indirectly increase algae cover and reduce the health of corals in what’s known as a trophic cascade.
A more personal note
In an age where our oceans are under enormous pressure from climate change, over fishing and various types of pollution, improving ecosystem resilience through the implementation of MPAs may be the best defense available. It’s up to all of us to ensure that marine protection efforts are not undermined by lack of MPAs, poor MPA design and policing, political meddling, lack of consensus, pseudoscience and damage from inappropriate land/water/recourse use adjacent to reserve areas. Our very survival as a species may depend on it.
A reef shark inside the Great Barrier Reef Marine Park, Australia, Kelli Anderson
If you can get past the first minute of this video you'll find some useful information :-)
Further Reading
Agardy, T., Notarbartolo di Sciara, G., Christie, P., 2011. Mind the gap: Addressing the shortcomings of marine protected areas through large scale marine spatial planning. Marine Policy. 35, 226-232. View Article.
Bond, M.E., Babcock, E.A., Pikitch, E.K., Abercrombie, D.L., Lamb, N.F., Chapman, D.D., 2012. Reef sharks exhibit site-fidelity and higher relative abundance in marine reserves on the Mesoamerican Barrier Reef. PLoS ONE. 7, e32983. View Article.
Fox, H.E., Mascia, M.B., Basurto, X., Costa, A., Glew, L., Heinemann, D., Karrer, L.B., Lester, S.E., Lombana, A.V., Pomeroy, R.S., Recchia, C.A., Roberts, C.M., Sanchirico, J.N., Pet-Soede, L., White, A.T., 2012. Reexamining the science of marine protected areas: linking knowledge to action. Conservation Letters. 5, 1 - 10. View Article.
Bond, M.E., Babcock, E.A., Pikitch, E.K., Abercrombie, D.L., Lamb, N.F., Chapman, D.D., 2012. Reef sharks exhibit site-fidelity and higher relative abundance in marine reserves on the Mesoamerican Barrier Reef. PLoS ONE. 7, e32983. View Article.
Fox, H.E., Mascia, M.B., Basurto, X., Costa, A., Glew, L., Heinemann, D., Karrer, L.B., Lester, S.E., Lombana, A.V., Pomeroy, R.S., Recchia, C.A., Roberts, C.M., Sanchirico, J.N., Pet-Soede, L., White, A.T., 2012. Reexamining the science of marine protected areas: linking knowledge to action. Conservation Letters. 5, 1 - 10. View Article.
International Union for Conservation of Nature. View Site.
Mumby, P.J., Harborne, A.R., 2010. Marine reserves enhance the recovery of corals on Caribbean reefs. PLoS ONE 5, e8657. View Article.
Rojas-Bracho, L., Reeves, R.R., Jaramillo-Legorreta, A., 2006. Conservation of the vaquita Phocoena sinus. Mammal Review. 36, 179-216. View Article.
Russ, G.R., Alcala, Angel, C., 2011. Enhanced biodiversity beyond marine reserve boundaries: the cup spillith over. Ecological Applications. 21, 241-250. View Article.
Mumby, P.J., Harborne, A.R., 2010. Marine reserves enhance the recovery of corals on Caribbean reefs. PLoS ONE 5, e8657. View Article.
Rojas-Bracho, L., Reeves, R.R., Jaramillo-Legorreta, A., 2006. Conservation of the vaquita Phocoena sinus. Mammal Review. 36, 179-216. View Article.
Russ, G.R., Alcala, Angel, C., 2011. Enhanced biodiversity beyond marine reserve boundaries: the cup spillith over. Ecological Applications. 21, 241-250. View Article.
World Wildlife Fund. View Site.