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Coral Reefs of the Southern Gulf of Mexico
By John W. Tunnell Jr., Ernesto A. Chávez, Kim Withers
Texas A&M University PressCopyright © 2007 John W. Tunnell Jr.
All rights reserved.
JOHN W. TUNNELL JR.
The first scientific account of coral reefs in the southern Gulf of Mexico was made by an expedition of scientists from the Academy of Natural Sciences of Philadelphia (now Philadelphia Academy of Sciences) in the early months of 1890. Expedition leader and academy director Professor Angelo Heilprin described the purpose of the expedition as "to investigate the natural history of the Yucatán Peninsula and Mexico." Publications resulting from the expedition related for the first time the tropical nature of marine biota of the southern Gulf of Mexico (corals and coral reefs, Heilprin 1890; echinoderms, Ives 1890; mollusks, Baker 1891; crustaceans, Ives 1891).
Professor Heilprin (1890) suggested that other scientists had not previously searched the area for coral reefs for two reasons. First, Darwin's classical work (1842) on the structure and distribution of coral reefs failed to mention reefs in the southern Gulf of Mexico. Second, scientists had feared contracting yellow fever in the Gulf. Heilprin discusses seven of the reefs and islands off the city of Veracruz, mentions 12 species of corals and 1 gorgonian, notes the "vast quantity of coral" used in construction (piers, seawall, and ancient houses), and includes figures of two old maps showing the reefs, dated 1806 and 1885 (Figs. 1.1 and 1.2). The magnificent old 16th-century castle, Fort San Juan de Ulúa, also made of coral, sits on the western (leeward) side of Gallega Reef, a nearshore reef now attached to the mainland by a land bridge (earthen fill). Ganivet (1998) listed six species of massive scleractinian corals used to construct the Fort San Juan de Ulúa: Siderastrea radians, Porites astreoides, Diploria spp., Colpophyllia natans, Montastraea annularis, and M. cavernosa.
In the southeastern Gulf of Mexico, the first biological accounts were of nesting seabirds on the islands of Alacrán and on Triángulos reef by the early English adventurer William Dampier (1699), who first visited the area in 1675. More than a century passed before others mentioned the vegetation, seabirds, sea turtles, and West Indian monk seal associated with these and other Campeche Bank islands (Smith 1838; Marion 1884; Ward 1887; Agassiz 1888).
In 1912, Joubin published a map of coral reefs that included the Gulf of Mexico (Fig. 1.3), but not until the 1950s was further research conducted on reefs in the southern Gulf. Smith (1954) utilized Joubin's (1912) map, Heilprin's (1890) work, and other unpublished sources and nautical charts (Table 1.1) to prepare an updated coral reef distribution map and list of coral species. Blanquilla Reef, the most northerly emergent reef in the western Gulf of Mexico, was briefly visited in 1955 by Donald R. Moore (1958). He described some of the invertebrate fauna of the reef, listing 44 species, including 11 stony corals, 3 gorgonian corals, 17 gastropods, 7 bivalves, 3 echinoids, 1 asteroid, and 1 holothuroid.
In a much larger and collaborative effort, Kornicker et al. (1959) studied Alacrán Reef, the most northerly reef on the Campeche Bank, which is just north of the Yucatán Peninsula. With funding primarily from the National Science Foundation, scientists from a number of different institutions participated in a productive expedition that quickly made Alacrán Reef one of the best-known Gulf reefs. The main focus of the expedition was the geology of Alacrán Reef, but a number of biological studies were published also, including descriptions of algae, island vegetation, foraminiferans, mollusks, fish, and birds (Tables 1.2 and 1.3).
In 1956, Emery (1963) sampled sediments offshore from the city of Veracruz and compared those reefs to reefs he had studied in the Pacific. His work was published in both English and Spanish in an international journal, raising the level of scientific interest in this unique geographic and geologic setting for coral reefs.
During the 1960s, interest and research on southern Gulf of Mexico coral reefs expanded to reefs throughout the Gulf. Researchers conducted field studies of coral reef systems during extended expeditions to remote locations. In their studies of the northern reefs of Veracruz state, Huerta M. and Barrientos (1965) reported on the marine benthic algae of Blanquilla and Isla de Lobos reefs, and Rigby and McIntire (1966) presented the first detailed information on the geology and ecology of Isla de Lobos Reef. Chamberlain (1966) recorded gorgonians from Lobos during the same expedition (Brigham Young University with Rigby and McIntire) and spent six weeks in the field studying Isla de Lobos Reef while staying on Lobos Island. Hidalgo (Hidalgo and Chávez 1967) and Chávez (Chávez et al. 1970; Chávez 1973; Bautista-Gil and Chávez 1977) both studied Isla de Lobos Reef during multiple expeditions with students from the Instituto Politécnico Nacional in Mexico City.
In the southwestern Gulf offshore from the city of Veracruz in southern Veracruz state, a number of students from the Universidad Nacional Autónoma de Mexico conducted their "professional thesis" (a significant project produced by students in Mexican universities at the end of a bachelor of science degree). Primarily under the direction of Dr. Alejandro Villalobos, these projects on various topics within the Veracruz reef system were subsequently published: marine flora, sponges, pteropods, copepods, Gecarcinus lateralis, chaetognaths, appendicularians, plankton, hydrology, and meteorology (Tables 1.2 and 1.3). Villalobos summarized much of this work in the proceedings of an international symposium on investigations and resources of the Caribbean Sea and adjacent regions (1971) and in a subsequent journal review article (1980). Two other contributions to the knowledge of southern Veracruz reefs were studies of algae (Huerta M. 1960) and foraminiferans (Lidz and Lidz 1966).
During the 1960s, three geologic studies were conducted on the southern Veracruz reefs: Morelock and Koenig (1967), Edwards (1969), and Freeland (1971). All three focused on the unique environmental setting of terrigenous sediments surrounding shallow-water coral reefs.
On the Campeche Bank or Yucatán Shelf in the southeastern Gulf, a major, multi-year study by the Department of Oceanography at Texas A&M University contributed greatly to the knowledge of carbonate sediments (Logan et al. 1969a, 1969b) and all coral reefs of the region (Logan 1962; Logan et al. 1969a, 1969b). This project, which was collaboratively funded by the National Science Foundation, the American Petroleum Institute, the Office of Naval Research, Shell Development Company, and Mobil Oil Company, extended from 1959 to 1963 and was the longest and most productive reef study in the southern Gulf to that date. It was an extension and expansion of the Kornicker et al. (1959) Alacrán Reef studies mentioned earlier. In addition, as a side project, one of the other Campeche Bank reefs, Cayo Arenas, was studied in more detail (Busby 1966). Fishes of Triángulos and Cayo Arenas reefs were first reported in the 1960s (H. Chávez 1966).
From the 1970s through the 1990s, three institutions were primarily responsible for the research, reports, thesis and dissertation projects, and publications on southern Gulf of Mexico coral reefs: Secretaría de Marina, Dirección General de Oceanografía; Texas A&M University–Corpus Christi (formerly Corpus Christi State University); and the Universidad Nacional Autónoma de México. In addition, in the late 1980s and 1990s, two institutions, Universidad Veracruzana in Jalapa and Centro de Investigación y Estudios Avanzados (CINVESTAV)–Unidad Mérida of the Instituto Politécnico Nacional, began research on the Veracruz reefs and Alacrán Reef, respectively. Most research during this timeframe focused on southwestern Gulf reefs.
The northern Veracruz reefs, due to their remoteness, are the least studied in the southwestern Gulf region. Of the six northern reefs, Isla de Lobos received the most attention in the form of studies of polychaetes, mollusks, crabs, and fish (Tables 1.2 and 1.3).
In the extreme southwestern Gulf, more than 20 coral reefs lie in two separate but adjacent groups, one offshore from the city of Veracruz and one offshore from the fishing village of Antón Lizardo. Because both these reef groups are more easily accessible than the northern Veracruz reefs, they have received much more study, and therefore, more information about them is available. Though most studies focused on individual reefs, some cover multiple reefs or the entire reef complex. Perhaps the most studied of all reefs in this region is Enmedio Reef. Gutiérrez et al. (1993) compared the coral reefs of the Veracruz region to those within the Sian Ka'an Biosphere Reserve of Quintana Roo along the Mexican Caribbean. For this book, we have categorized and listed the extensive studies in this region by reef (Table 1.2) and by topic (Table 1.3).
The oceanographic program within the Mexican Navy (Instituto de Investigación Oceanográfica del Golfo y Mar Caribe) has contributed significant information on the Veracruz Reef System, as well as on reef biology, over the past 25 years. This program first operated from a small station (Estación Oceanográfica) in the city of Veracruz but is now housed within a new institute building just south of the Mexican Naval Academy at Antón Lizardo.
In the southeastern Gulf on the Campeche Bank, great distance from shore continued to limit the number of reef studies. Apparently, only one paper was published on these reefs during the 1970s: a report on the thickest recorded Holocene reef section, located on Alacrán Reef (Macintyre et al. 1977). During the 1980s, researchers characterized coral diversity and zonation on Cayo Arenas Reef, reviewed all Mexican Atlantic coral reefs, presented environmental problems and human impacts on southern Gulf and Caribbean coral reefs, and published the distribution of the fish fauna associated with all Campeche Bank reefs (Tables 1.2 and 1.3).
During the 1990s, studies continued on both Campeche Bank and the Veracruz Reef System. Organismal and biological studies covered algae, sponge-associated fauna, corals, mollusks, stomatopods, decapods, and fish. Ecological studies covered benthic communities, zonation and community structure, ecosystem connectivity, and marine resources. Other studies focused on reef sediments and a computer simulation model of reef growth (Tables 1.2 and 1.3).
Most recently, a number of fish studies have appeared, especially on Alacrán Reef from the laboratory of Ernesto Arias- González at CINVESTAV in Mérida. Some biological studies include several on Montastraea annularis growth rates, gorgonian diversity and connectivity, polychaetes, mollusks, and nesting seabirds associated with Campeche Bank reef islands. Other recent studies have been on geologic facies through time on Campeche Bank reefs and the utilization of Landsat Thematic Mapper data for mapping coral reef bathymetry (Tables 1.2 and 1.3).
Jordán-Dahlgren and Rodríguez-Martínez (2003) provide one of the latest summaries of all Mexican coral reefs within the Gulf of Mexico and Caribbean in the excellent book on all Latin American coral reefs (Cortés 2003). Most recently, Jordán-Dahlgren (2004) provided a brief environmental diagnosis or status report on southern Gulf reefs. Overall, the reefs in the extreme southern Gulf that lie off the city of Veracruz and village of Antón Lizardo have been most impacted and those on the Campeche Bank least impacted. The reefs near Tuxpan in northern Veracruz are intermediate. Chapters 5, 6, 12, and 13 provide further details.CHAPTER 2
JOHN W. TUNNELL JR.
There are 46 named coral reefs in the southern Gulf of Mexico. Of these, 31 are the Veracruz Shelf reefs (VSR) in the southwestern Gulf off the state of Veracruz, and 15 are the Campeche Bank reefs (CBR) in the southeastern Gulf (Table 2.1, Fig. 2.1). Other named and unnamed shoals and banks have yet to be explored; these likely have coral communities as well. Dahlgren (1993), for instance, lists approximately 10 named and more than 25 unnamed banks (topographic highs and reefs) on the Campeche Bank for which there is little or no scientific information.
Coral reefs in the southwestern Gulf are typically located nearshore (<200 m) to mid-shelf (22 km) on a narrow terrigenous continental shelf (Morelock and Koenig 1967). The climate here is subhumid to humid and has high rainfall and substantial mainland drainage. In the southeastern Gulf, reefs are located on a wide carbonate shelf, primarily along the 55 m contour on the outer shelf, and range from 130 to more than 200 km offshore (Tunnell 1992). In contrast to the southwestern Gulf, the climate here is semiarid. The southeastern Gulf reefs are surrounded by oceanic Caribbean waters from the Yucatán Channel and are not affected by mainland drainage. The southern Gulf reefs are submerged "mountain-like" structures scattered across the continental shelf, in contrast to the scattered patch reefs in nearby low-energy coastal areas such as the Florida Keys and Belize, where mangroves line the shoreline and seagrasses predominate as submarine vegetation nearshore. Mainland shorelines are moderate-energy sandy beaches or rocky shores (volcanic) in the southwestern Gulf and low-energy sandy beaches or rocky shores (limestone) in the southeastern Gulf.
The southwestern Gulf coral reefs are clustered in two systems, each within two subgroups: the Tuxpan Reef System (TRS) and Veracruz Reef System (VRS). To the north there are six emergent platform reefs in the TRS, three of which are grouped off Cabo Rojo and three northeast of Tuxpan (Fig. 2.2). Isla de Lobos Reef is the only one in the TRS that has an island, and consequently is the best known because the island has served as an adequate base camp for extended expeditions (e.g., Rigby and McIntire 1966; Chávez et al. 1970; Ray 1974; Tunnell 1974; Roberts 1981; Allen 1982). Blanquilla Reef is the most northerly emergent coral reef in the western Gulf of Mexico (Moore 1958).
The VRS in the far southwestern Gulf of Mexico comprises 25 coral reefs in two subgroups, one consisting of smaller reefs nearshore and one with mostly larger reefs extending farther offshore (Fig. 2.3). The first, or northern, group of 13 reefs lies offshore from the city of Veracruz (Fig. 2.4) and is composed of eight emergent platform reefs (Gallequilla, Anegada de Adentro, La Blanquilla, La Gallega, Pájaros, Isla Verde, Tierra Nueva, and Isla Sacrificios), two submerged bank reefs (or submerged patch reefs Bajo Mersey and Lavandera), and three fringing reefs (Punta Gorda–Punta Majahua, Hornos, and Punta Mocambo). It is important to note that one historical reef, Punta Caleta, a fringing reef, was destroyed during the development of the Port of Veracruz, and in the 1600s, part of La Gallega Reef was used to build Fort San Juan de Ulúa for protection of the city and harbor. Subsequently, at the beginning of the 20th century, a land bridge was extended from Punta Caleta on the mainland to the fort on La Gallega Reef to partially enclose the Port of Veracruz on the north side (compare the historical maps in Figs. 1.1 and 1.2 to Fig. 2.4).
Three of the reef platforms in the northern VRS are associated with islands: La Blanquilla, Isla Verde, and Isla Sacrificios (Fig. 2.4). La Blanquillas island is a sandy cay, always changing shape and size, whereas Isla Verde and Isla Sacrificios are densely vegetated and fairly stable. Isla Verde's vegetation is low and mostly natural, although transplanted almond trees provide a shady canopy over part of the island. Isla Sacrificios has a large, important lighthouse, a public visitors' area, and many exotic transplants among the natural vegetation (see chapter 11 for more information on island biota).
Excerpted from Coral Reefs of the Southern Gulf of Mexico by John W. Tunnell Jr., Ernesto A. Chávez, Kim Withers. Copyright © 2007 John W. Tunnell Jr.. Excerpted by permission of Texas A&M University Press.
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