Lagoons Reefs of Alacranes Reef and Chinchorro Bank: Ocean Reef of Mexican Atlantic DOI: http://dx.doi.org/10.5772/intechopen.88662

species of birds are registered. Several of them registered in NOM-059-ECOL-1994 as subject to special protection, for example, the blue-winged teal (Anas discors) and the roadside hawk (Buteo magnirostris). The brown heron (Ardea herodias) is considered rare. For example, the blue-winged teal (Anas discors) and the road hawk (Buteo magnirostris), the brown heron (Ardea herodias) is considered rare, the stork (Mycteria americana) and the rabies or rabihorcado (Fregata magnificens) as it is known in the locality where, according to fishermen's reports, this bird reached great abundance they have the category of threatened. Within the reptiles, the American crocodile (Crocodylus acutus) is listed as endangered, although apparently in the bank, this species is abundant.

The known composition of the coral taxa is represented by hexacorals, octocorals, and hidrozoarios with 95 species reported [14]; in this assessment we report 31. Among the Scleractinian Orbicella annularis, M. cavernosa, Porites astreoides, Agaricia tenuifolia, A. agaricites, Acropora palmata, and A. cervicornis dominate, while of the gorgonian the dominant ones correspond to Eunicea mammosa, Gorgonia flabellum, P. americana, Briareum asbestinum, and Plexaura flexuosa. The hidrozoarios are represented by Millepora complanata and M. alcicornis like the report by other investigation [57]. The macroinvertebrates are conspicuous elements of the coral reef; they are even organisms of great scientific, tourist, and commercial interest, but little is known of those that are presented in the reserve. The available records, which are not exhaustive, correspond to 35 species of sponges, 78 gastropods, 26 bivalves, and 6 crustaceans [14]. For Chinchorro Bank, faunal and floristic inventories with which it is counted in the reserve are partial. It is not known the composition of zooplankton, phytoplankton, microzoobenthos, and microphytobenthos, among others, as well as taxonomic groups of which there are no records such as the case of echinoderms, jellyfish, anemones, crustacean by marine fauna, and arachnids, insects, and mammals for terrestrial fauna is not known.

With the high values of diversity in Alacranes reef, one would think that it is the most diverse and most conserved reef; however, the high coverage values in Chinchorro Bank belie that assumption. It is very important to mention that the coverage composition of benthic organisms is a variable that determines total biodiversity or specific group biodiversity, such as benthic organisms, invertebrates, or reef fish [58]. Both lagoons have hard and soft corals in different proportions, but abundance has a high variation in soft corals. This may be related to the high colonization capacity of soft corals which adhere to different types of substrate.

The south part of Chinchorro Bank recorded the highest diversity of benthic groups, but Alacranes reef was in the north. Density and percentage of live coral coverage, particularly reef building corals in these areas, are slightly over the average recorded in coral reefs from the Mesoamerican Reef [59]. It is possible that these corals enhance considerably the growth of new colonies, which will make possible the persistence of reefs and the habitat they provide to other species. In the north of Chinchorro and the south of Alacranes, it is highly probable that sedimentation condition will affect and reduce the live coral coverage, since this condition persists for a period; about 7% of coral coverage in this area could be lost because it is well known that sediments damage coral polyp tissues by abrasion and asphyxia.

#### 4.2 Site affinity

There are distinct morphological variations between leeward and windward sectors. A shallow and extensive reef flat is a common feature in most of leeward part of these reefs. Coralline algae are quite abundant in these flats, and rubble of coral skeletons in ample dead beds of hard corals is evident. With both data sets, the classification

are represented by Porites asteroids, Pseudodiploria strigosa, Acropora palmata, and A. cervicornis, mainly. In the southern part of the barrier, Acropora prolifera, a rare species in the Caribbean reefs, is located. The reef crest reaches up to 400 m wide and marks the maximum growth of the reef and is only interrupted by two channels of flow and reflux tidal in the area known as the flooded. The boundary between the crest and the inner barrier is not clearly defined, but it can be said that it starts in the area where the swell train begins to disappear. In the inner barrier, in the closest part to the crest, Acropora palmata, A. cervicornis, Porites porites, P. astreoides, and Millepora alcicornis are the corals competing with Palythoa. To the west the inner barrier comprises the meadows of seagrass and the canals near the barrier. Of these components, the seagrass meadows play an important role in the system [53]. They are presented in shallows of sandy bottoms covered by meadows of Thalassia testudinum, Cymodocea manatorum, and Diplanthera wrightii whose roots and rhizomes form a dense plot that functions as a sediment trap and stabilizes the substrate. Associated with the meadows are presented corals Manicina areolata, Oculina diffusa, and Porites porites. The reef plateau is the most complex area of reef lagoon and includes shallow seagrass meadows, pinnacular reefs, and microatolls, as well as an intricate network of canals, the result of these morphological structures that rise abruptly from 12 to 15 m deep, until almost reaching the surface. Orbicella annularis is dominant and accompanies M. cavernosa, Pseudodiploria strigosa, Colpophylia

Lagoon Environments Around the World - A Scientific Perspective

natans, Porites porites, P. astreoides, and Stephanocoenia intersepta.

For its biological characteristics, the reserve of Chinchorro Bank is a natural laboratory, practically unaltered, partially known, and even unknown in many of its aspects, to develop innovative scientific research and quality focused both on the execution of floristic and faunal inventories that enrich and update existing ones, as well as to understand in detail the biological and ecological relationships and processes that develop there. Due to Chinchorro Bank's geographical isolation and its position in the hurricanes and tropical storms route, it is important to establish mechanisms to facilitate the knowledge of the prevailing meteorological conditions to increase the safety degree of visitors and fishermen. Unlike other Mexican reefs, Banco Chinchorro does not develop on a continental or insular shelf but on a deep underwater crest (more than 400 m deep about 30 km out coast), which rises like a pinnacle [54, 55]. Little is known of its origin; we have the theory that in the past, the reef complex was formed by separation and derives from a portion of the continental coastal area, possibly in the Cenozoic era in the late Tertiary period or early Quaternary (in the Pliocene-Pleistocene age). The separate fraction of the coastline contained a fringe or marginal reef and coastal lagoons with typical fauna. The detachment of part of the coast was possibly of a single plate, which took with it a large reservoir of ancient water which possessed characteristics of a continental mass of water, which has maintained its characteristics with the contribution of the rains. Due to its geographical position in the Western Caribbean and their influence in the Gulf Stream, it is an intermediate point compared to other reef systems located downstream in the Lesser Antilles, which allows it to receive larvae of these

distant places and in turn export larvae of different organisms generated in

of Florida, among others [56].

220

Chinchorro to systems located upstream, like Cozumel, Alacranes reef, and the keys

The Chinchorro Bank is of great ecological importance due to the high diversity of organisms that are there. By remaining practically isolated for a long time, some areas are unchanged, allowing for a comparable study with other similar ecosystems. Banco Chinchorro is nominated by UNESCO as a World Heritage Site and as a Ramsar site for the protection of migratory birds and wetlands. It was recently designated as the Man and Biosphere (MAB) site [50]. The fauna inventoried by the management program [14] is dominated by local and migratory birds that use the keys permanently or during the time of migration to rest and feed. Ninety-six

analysis leads to effectively recognizing the quantitative differences between the different zones. It extracts subjective considerations and discovers the importance of the ecological attributes identified in the field. However, in some cases the factors that originate the distribution patterns are not clearly discovered, since the analysis conducted suggests that significant changes with the depth occurs in the populations and shows that the different parts of the same reef system can be subjected to different pressures and combinations in the selection process, even in physiographical areas related to the frequency and intensity of disturbance by the wave.

• The proportion of live coverage in Chinchorro Bank is higher than in the

Lagoons Reefs of Alacranes Reef and Chinchorro Bank: Ocean Reef of Mexican Atlantic

• The abundance-rich ratio of species given by diversity is similar in both

• In the lagoons there were site affinities, especially at the edges, that faithfully identify windward and leeward areas, which allow to infer the importance of this element and what originates in relation to wave force,

• The analyses show areas with large ecological differences in the lagoons.

well as preserving the reef landscape and its natural elements, for the

and maintenance of these magnificent ecosystems.

enjoyment, recreation, exploitation, and elevation of the quality of life of social groups and visitors and for future generations. It should also encourage the conduct of research and studies that broaden and deepen this knowledge and contribute to the development of methods and alternatives for the sustainable use

The benchmarks of reefs in Mexico are changing, and they need to be redefined frequently to update them, in order for the management tools to be more effective and accurate; we hope that this contribution will go in that direction of conservation

We would like to extend our thanks to the National Council of Science and Technology for the support given to the realization of several projects in which this field work is included. Likewise, we thank the Marine Secretariat and the fishermen of several cooperatives, for the transfer of personnel and students to the different reefs and to all the people and institutions that contributed resources, time, and

By virtue of its insular nature and the scarcity of freshwater, both reefs have remained safe from major alterations. Alacranes reef and Chinchorro Bank are a distant paradise that still have abundant fishing resources and diverse underwater life to marvel, as well as the possibility of discovering hidden secrets kept by the sea and time. However, we must consider and not forget that the overexploitation of resources can deplete the productivity of this place, which until now is one of the last places where coral reefs and memories of other times remain intact. The knowledge obtained from these systems must serve to conserve their natural resources, with special emphasis on endemic species, threatened, endangered, special protection, and those of current and potential economic importance, as

• While the richness is greater in the lagoon of the Alacranes reef, the magnitude of the Chinchorro Bank lagoon may result in an undervaluation due to

• Orbicella annularis is the coral that is among the five most dominant species in

Alacranes reef.

lagoons.

of resources.

223

Acknowledgements

knowledge to carry out this research.

both lagoons.

oxygenation, etc.

insufficient sampling.

DOI: http://dx.doi.org/10.5772/intechopen.88662

The affinities between the sites showed strong identities toward identifying areas with particular characteristics such as windward, leeward, and the reef ridge; however, the inclusion of some site of the reef plain in these groups can be caused by the depth and the type of biotope that develops there (availability of free substrate, coral fragments, etc.) as happens in other reef sites [60]. Chinchorro Bank presented a greater number of groupings, showing particular areas with strong characterization, where slight changes in some parameters is sufficient for the index to detect and separate them; Alacranes gathers more sites in its clusters, which would allow to think that their affinities are maintained in a larger area.

## 4.3 Spatial species distribution

In stable ecological systems, it is possible to recognize the dynamic state in which all the interactions and variations of a community are centered and nullified at a point of equilibrium to which all the components of the community are directed after a disturbance, allowing the community to be recognized as an entity based on its attributes [61–63], which are the total abundance of species, the total abundance of the dominant species, the biomass of the community, and the composition of species [64, 65]. With the analysis of Main Coordinates, it's possible to identify a community for the species that most influence its community spatial structure [66]; however, this community could present different points of stability, in which the dominance of different species is present, which they present specific equilibrium points, providing different levels of resistance to disturbances, as could create the differences between windward and leeward levels. In both reefs and analysis strategies, the species that takes advantage of the largest amount of resources for its benefit and consequently is the most dominant is Orbicella annularis, which is similar to that reported for the Netherlands Antilles [67], on both reefs was a species that separates from any grouping, being more evident in Chinchorro Bank. However, in areas with a certain degree of disturbance, the scheme changes dramatically, and other species replace O. annularis in its dominance. In the first case, when solid substrate is available, the gorgonians are those that have more aggressiveness and in the second when missing a solid substrate, the group of sponges has some advantage. In fact, these data confirm what was partially found by other research [68–70] who defined areas or biotopes with strong ecological differences. Coral reefs in the Caribbean and Gulf of Mexico have a similar coral biota. Nevertheless, there is a reduction in the number of common Scleractinian coral species from the Alacranes reef to Chinchorro Bank. Coral species richness, however, does not seem to decrease drastically as it does with gorgonians [71].
