2.2 Methods

21 m in the south, 3–4 m near Cayo Centro, and 2 m in the north. A Thalassia testudinum seagrass bed and garden eels, sometimes at high densities, are found in the reef lagoon. The reef lagoon extends for several tens of kilometers west of the bank and is extremely productive [13]. Under its waters the first thing we identify are sponges, fans and sea whips, and isolated colonies of stony corals and a huge diversity of multicolored reef fishes or small fish that are by hundreds hidden under the rocky cavities of where they come out and create a lively silver spot. However, the diversity and abundance of someone groups (e.g., the management program [14] reports 95 species of Cnidaria, 35 sponges, 96 birds, 11 reptilian, 135 algae, and 104 species of mollusk), the main fauna inhabiting this tropical ecosystem is practically unknown (cichlid, crocodiles, etc.). Some of this species have never been described; maybe others are relict species, and others are a complex of subspecies interacting biologically and ecologically between them. Aggregation of the queen conch (Strombus gigas) and spiny lobsters (Panulirus argus) and abundance of large fish are frequent; turtles probably occur too. Cayo Centro is an important breeding site for frigate birds (Fregata magnificens) and olivaceous cormorant (Phalacrocorax

Lagoon Environments Around the World - A Scientific Perspective

olivaceous). The area is fished for queen conch (Strombus gigas) and lobster (Panulirus argus) by fishermen from Xcalac and Chetumal; there are three fishery cooperatives with 60–70 elements each one; the current disturbance for fishing is probably small, because of a forbidden period for the Fishery Secretary decree [14]. There are two lighthouses and many wrecks. The reef is gradually becoming popular with scuba divers who make 4- to 5-day trips from Cancún, Cozumel, and Quintana Roo coasts. The area has frequent climatological disturbance (winds of the

north and south and hurricanes) (Figure 1).

Figure 1.

212

Sampling sites in both oceanic reefs.
