Coral Reefs of the Southern Gulf of Mexico

Chapter 13. Conservation and Management

2 Conservation and Management Ernesto A. Chávez and John W. Tunnell Jr. Coral reef ecosystems in the southern Gulf of Mexico provide services (e.g., fishery support, storm protection) and revenue (e.g., fishing, tourism, oil exploration ) in a variety of ways to adjacent coastal communities. Loss of these coral reef resources would have tremendous social impacts related to loss of work, income, and potentially, an important food source for many artisanal fishing communities . The value of natural capital like coral reefs is determined by estimating how changes in the services they provide will affect human welfare (Costanza et al. 1997). The value of coral reefs has been estimated at $6,075.00 ha–1 yr–1 . The coral reefs of the southern Gulf of Mexico cover an area of approximately 33,024 ha, with a total annual value of $200,622,471 (Table 13.1). Because of the value of these ecosystems and because the activities that provide muchneeded income and/or food to coastal communities have great potential to disturb or destroy the reefs, it is crucial to understand the threats to the health of these ecosystems so that workable management strategies for conservation and sustainable use can be formulated. Natural and anthropogenic threats to coral reefs in the southern Gulf of Mexico were detailed by Horta-Puga in chapter 12 (this volume). Briefly, natural disturbances to these reefs are sedimentation and low salinity due to river inflow (Veracruz reefs only), meteorological events (winter cold fronts, tropical cyclones), reef species die-off (especially the long-spined sea urchin Diadema and scleractinian corals in the genus Acropora), increased sea-surface temperatures , coral bleaching and disease, and algal blooms, including red tides (Table 13.2). Anthropogenic disturbances that affect the reefs are coastal construction, dredging and filling, including mangrove destruction, point and nonpoint source pollution, especially organic enrichment from untreated sewage effluent, watershed deforestation and concomitant increased sedimentation and freshwater inflow, boat traffic (anchoring, ship grounding), tourism (littering, trampling, diver damage, coral collection), fishing and overfishing, and historically, coral mining for building materials. Many natural disturbances can be exacerbated by anthropogenic disturbances, such as algal blooms (organic enrichment) and sedimentation impacts (deforestation). The reefs in the Gulf of Mexico have been moderately to severely impacted by human activities (Chávez and Hidalgo 1988, 1989; Chávez and Tunnell 1993, Tunnell 1992; Vergara et al. 2000). The Veracruz reefs have suffered the greatest damage, due to their proximity to the coast and coastal drainages and to important population centers and ports such as Veracruz, Tuxpan, and Coatzacoalcos . Coral cover on Veracruz reefs has been reduced to 17% or less (HortaPuga 2003), primarily due to increased sedimentation resulting from changing land use upstream and due to fishing and tourism activities. Coastal development , especially near the city of Veracruz, has significantly impacted the reefs 13 A4339.indb 142 A4339.indb 142 7/6/07 11:19:35 AM 7/6/07 11:19:35 AM Conservation and Management 143 through increased turbidity and organic loading. Deforestation of upper ridges of the Sierra Madre Orientál has led to erosion, causing significant siltation of these reefs, and this problem is often aggravated by the input of fertilizers, pesticides , and other pollutants from agricultural practices on the coastal plains. Less than 10% of wastewater receives treatment before being discharged into coastal waters, causing eutrophication and accelerated algal growth. In addition , tourist-related threats have increased tremendously. Both commercial and recreational fishing pressures and spear fishing have led to significant declines in fish, lobster (Panulirus spp.), conch (Strombus spp.), and coral populations. The Campeche Bank reefs are in better condition due to greater distance from shore, low human population on adjacent coastlines, and no freshwater inflow. However, the oil terminal near Cayo Arcas, associated construction activities, tanker traffic, and offshore oil reserves adjacent to the reefs as well as tourismrelated activities are potential threats. The reefs in the southern Gulf of México have also been impacted by natural damage from hurricanes. Prolonged algal blooms followed the Caribbeanwide mass mortalities of the long-spined sea urchin in 1983. Reduced herbivory, due to the loss of long-spined sea urchin and chronic overfishing of herbivorous fishes (e.g., parrotfish), has allowed algae to replace coral in many areas (T. J. Nelson 1991). In addition, outbreaks of coral diseases, possibly exacerbated by human-induced stress and global warming, have become a concern during the last few years (Jordán-Dahlgren 2004). Several initiatives have been put forth...