Marine protected areas (MPAs) are important tools for the conservation of marine species and ocean ecosystems. They are most often designed to protect and restore declining marine communities and their habitats, but they can also be established to sustain human relationships with the ocean. Incorporating an understanding of ecological connections in MPA management can extend the strategic importance of individual MPAs beyond their geographic borders. The linking of MPAs through their ecological connections and common management strategies is a way to create a functional network of conservation actions and allow MPAs to work in unison to accomplish more than they would if they were considered ecologically and socially isolated from one another.¹

Ocean currents and the movement of marine species physically and biologically connect marine environments in the United States to the nations of the Caribbean. As a result, the condition of the marine ecosystem in the US is fundamentally linked to the condition of marine areas in other parts of the region. Marine species or their offspring move freely across the complex mosaic of territorial exclusive economic zones and national borders in the Caribbean. It is therefore essential that the United States works beyond its physical jurisdictions to cooperate with the other nations of the Caribbean to improve the health of their shared ocean environment.

Conservation efforts in marine and terrestrial protected areas are usually focused on conserving local habitats and biological populations. However, ecological connections can spread the benefits of these local efforts over a larger geographic area. As a result, the conservation success of an individual protected area may have an important ecological value to other protected areas in a region.² This provides an incentive to better understand how protected area ecosystems are connected and for governments to cooperate in using this understanding to create joint management actions. This is particularly important for conserving coral reef ecosystems.³

Coral Reef Connections

Many species of corals undergo synchronous spawning events at particular times of the year.⁴ This simultaneous release of eggs and sperm by the millions of tiny polyps that make up coral colonies increases the probability of a species’ reproductive success. Water currents carry the coral larvae that result from these events to sites where they settle and begin new coral colonies. The settlement may occur on the same reef, or at reefs hundreds of miles from the larvae’s parent colonies. This process of reproduction, larvae dispersal, and settlement is fundamental for sustaining coral reef communities and increasing their resiliency.

Figure 1

Ocean circulation in the Wider Caribbean.  Modeling of ocean currents reveals their speed (color: cm/sec) and direction (arrows). This snapshot from July 31, 2021 shows the complex pattern of circulation that connects the Caribbean region through physically distributing marine species as well as waterborne threats to those species and their communities. Image credit: Consortium for Data-Assimilative Ocean Modeling at the US Naval Research Laboratory.⁵

To evaluate the links between coral populations in different parts of the Caribbean, marine scientist Steven Schill and his colleagues used regional ocean circulation data and an understanding of coral reproduction and larval biology to construct a model of larvae dispersal patterns between coral reefs.⁶ Their results show the important ecological connections between sources and destinations of coral larvae across the Caribbean.

Using their data, we prepared the following figures showing the Caribbean connections to the coral reefs in the MPAs of the Florida Keys, Dry Tortugas, and Flower Garden Banks. These figures use data on ocean circulation and coral reproduction, larvae dispersal, and settlement. The straight lines represent the relative strength of the connections from the larvae sources to US MPAs, but the actual pathways vary in length and trajectory because they are defined by ocean circulation patterns.

Figure 2

Modeled ecological connections of coral larvae from reefs across the Caribbean Sea and that settle in the Florida Keys National Marine Sanctuary (FKNMS). Lines show the specific location of reefs in international jurisdictions sourcing coral larvae to the FKNMS reef system via ocean currents. Line width represents the strength (relative abundance of larvae) of the connectivity between the two reef systems. Modeled data by the authors used with permission from Schill et al., 2015. Credit: authors.

Figure 3

Modeled ecological connections of coral larvae from reefs across the Caribbean Sea and that settle in the Dry Tortugas National Park (DTNP). Lines show the specific location of reefs in international jurisdictions sourcing coral larvae to the DTNP reef system via ocean currents. Line width represents the strength (relative abundance of larvae) of the connectivity between the two reef systems. Modeled data by the authors used with permission from Schill et al., 2015. Credit: authors.

Figure 4

Modeled ecological connections of coral larvae from reefs in the southern Gulf of Mexico and beyond and that settle in the Flower Garden Banks National Marine Sanctuary (FGBNMS). Lines show the specific location of reefs in international jurisdictions sourcing coral larvae to the FGBNMS reef system via ocean currents. Line width represents the strength (relative abundance of larvae) of the connectivity between the two reef systems. Modeled data by the authors used with permission from Schill et al., 2015. Credit: authors.

The reproductive condition of coral and fish populations in a marine protected area influences the amount of larvae they produce. Numerous physical and biological factors determine the number and fate of these larvae. If coral reefs upstream can produce large numbers of larvae and these larvae are able to survive, the ecological resiliency of coral reef populations downstream is increased. The resiliency of downstream coral reefs also increases if the number of sources for larvae is large. While some connections are weaker than others, strong local larvae retention and numerous weaker regional connections have the potential to rebuild coral reef populations in places where they have been reduced. This is particularly important for the coral reefs in the Florida Keys where coral diseases and the impact of warming seas over the last few decades have caused significant losses.

A recent report by the UN Environment Programme’s Cartagena Convention Secretariat⁷ used coral larvae dispersal models and other biological data to analyze the connectivity among Caribbean marine protected areas listed under the Cartagena Convention’s Special Protected Areas and Wildlife (SPAW) Protocol, to which the United States is a party. This report could serve as a roadmap for building cooperation between all the MPAs of the region. It evaluated the strength of ecological links between the SPAW sites as a basis for developing coordinated conservation science and management strategies, specifically bilateral and multilateral approaches among jurisdictions to locate and design networks of marine protected areas, manage endangered and invasive species, respond to ocean-borne pathogens and pollution, and sustain trans-boundary fisheries.

Strengthening Existing Connections and Building New Ones

The ecological exchange between healthy and declining coral reefs highlights the need for marine conservation programs in the United States to work collaboratively with its neighbors to ensure that healthy connections are maintained and ecosystem threats in the region are identified. The Gulf of Mexico Large Marine Ecosystem⁸ and the Caribbean & North Brazil Shelf Large Marine Ecosystem⁹ projects provide a formal framework within which the US can develop the necessary collaborations. These projects are intergovernmental initiatives designed to sustainably manage fisheries and protect the marine environment within transnational ocean areas. Engaging with nations through such mechanisms aligns with the Biden administration’s announced policies for international engagement to address climate change and protect the planet’s critical ecosystems, and links cooperation among protected areas to the administration’s stated goal of protecting thirty percent of the nation’s land and water by 2030.¹⁰

In 2015, the United States and Cuba signed a joint accord¹¹ to cooperate on the science and management of marine protected areas. This memorandum of understanding was part of a joint vision for environmental protection.¹² However, since this arrangement with Cuba has not been possible to implement, The Ocean Foundation, through its Trinational Initiative, has been working to maintain this vision for cooperation on protected areas.¹³ Reviving a formal collaboration mechanism would demonstrate that the United States and Cuba recognize that the future health and resiliency of its shared ocean ecosystem depends on the strength of the diplomatic as well as the ecological connections between the two countries. American and Cuban scientists, marine protected area staff, and ocean resources managers would have a renewed opportunity to learn from each other’s experiences, local ecological security would improve, and a foundation would be laid for a productive relationship beyond just ocean connections.¹⁴ Most importantly, it would demonstrate leadership in overcoming barriers between nations that impede development of new approaches for jointly addressing the drivers and consequences of a rapidly changing global environment.

In a time of frayed relations and diplomatic challenges between governments, understanding how the well-being of countries are linked through their connected ecosystems and environments may provide an important bridge to cross diplomatic divides.  Productive and resilient ecosystems from the tropics to the poles are built on intimate and distant connections.  By engaging in the international science needed to document these connections and embracing our common interests to protect the earth’s special places, we will be fostering more productive and resilient relationships among nations.

Endnotes

1. IUCN World Commission on Protected Areas (IUCN-WCPA), Establishing Marine Protected Area Networks—Making It Happen (Washington, D.C.: IUCN-WCPA, National Oceanic and Atmospheric Administration and The Nature Conservancy, 2008), www.iucn.org/sites/dev/files/import/downloads/mpanetworksmakingithappen_en.pdf; Kirsten Grorud-Colvert et al., "The MPA Guide: A Framework to Achieve Global Goals for the Ocean," Science 373, no. 6560 (2021), https://www.science.org/doi/abs/10.1126/science.abf0861; Jenna Sullivan-Stack et al., "A Scientific Synthesis of Marine Protected Areas in the United States: Status and Recommendations." Frontiers in Marine Science 9 (2022): 849927 https://www.frontiersin.org/articles/10.3389/fmars.2022.849927/full
2. Jodi Hilty et al., Guidelines for Conserving Connectivity through Ecological Networks and Corridors (Gland, Switzerland: IUCN, 2020), https://portals.iucn.org/library/node/49061.
3. Diego L. Gil-Agudelo et al., “Coral Reefs in the Gulf of Mexico Large Marine Ecosystem: Conservation Status, Challenges, and Opportunities,” Frontiers in Marine Science 6 (2020): 807, www.frontiersin.org/articles/10.3389/fmars.2019.00807/full.
4. Stephen R. Gittings et al., “Mass Spawning and Reproductive Viability of Reef Corals at the East Flower Garden Bank, Northwest Gulf of Mexico,” Bulletin of Marine Science 51, no. 3 (1992): 420–428.
5. Consortium for Data-Assimilative Ocean Modeling, www7320.nrlssc.navy.mil/GLBhycomcice1-12/intram.html
6. Steven R. Schill et al., “No Reef is an Island: Integrating Coral Reef Connectivity Data into the Design of Regional-Scale Marine Protected Area Networks,” PLoS One 10 (2015): e0144199
7. William Kiene, “An Evaluation of Connectivity Between the SPAW-Listed Protected Areas to Guide the Development of a Functional Ecological Network of Protected Areas in the Wider Caribbean,” UN Environment Program, Report to the Ninth Meeting of the Scientific and Technical Advisory Committee (STAC) to the Protocol Concerning Specially Protected Areas and Wildlife (SPAW) in the Wider Caribbean Region, March 17–19, 2021, http://gefcrew.org/carrcu/SPAWSTAC9/Info-Docs/WG.42-INF10-en.pdf.
8. Gulf of Mexico Large Marine Ecosystem, https://gomlme.iwlearn.org/en.
9. The Caribbean and North Brazil Shelf (CLME+), https://clmeplus.org.
10. The White House, “Executive Order on Tackling the Climate Crisis at Home and Abroad,” www.whitehouse.gov/briefing-room/presidential-actions/2021/01/27/executive-order-on-tackling-the-climate-crisis-at-home-and-abroad.
11. “Memorandum of Understanding Between National Oceanic and Atmospheric Administration, United States Department of Commerce, and National Park Service, United States, Department of Interior, of the one part, and Republic of Cuba Ministry of Science, Technology and Environment, National Center for Protected Areas, of the other part, on Cooperation in the Conservation and Management of Marine Protected Areas,” www.edf.org/sites/default/files/us-cuba-mou-english.pdf.
12. “Joint Statement Between the Republic of Cuba and the United States of America on Cooperation on Environmental Protection,” https://2009-2017.state.gov/e/oes/rls/pr/249946.htm.
13. La Red de Áreas Marinas Protegidas del Golfo de México (RedGolfo), www.redgolfo.org/about.html.
14. Brian M. Boom, “Biodiversity without Borders: Advancing U.S.-Cuba Cooperation through Environmental Research,” Science & Diplomacy, August 14, 2012, www.sciencediplomacy.org/article/2012/biodiversity-without-borders; Richard Stone and Allie Wilkinson,  “Researchers applaud U.S.-Cuba accord: End of Cold War estrangement could aid joint scientific projects,” ScienceInsider, December 17, 2014, www.science.org/content/article/researchers-applaud-us-cuba-accord; Margaret E. Crahan, ed., Cuba-US Working Together Again: Lessons from Environmental Cooperation, Columbia Cuba Program, 2021, https://ilas.columbia.edu/sites/default/files/content/US-Cuba%20Working%20Together_Book.pdf.