Abundance of Diadema antillarum (Echinodermata: Echinoidea) on the coast of Venezuela: 1975-2003

Study Extent

To evaluate the recent density of some populations of D. antillarum along the coasts of Venezuela.

Sampling

A total of six locations on the coast of Venezuela were evaluated, of which five are located on the continental coast (Mochima National Park, Ensenada de Oricao, Ensenada de Chichiriviche de la Costa, Morrocoy National Park, and Cuare Wildlife Refuge) and one in the oceanic area (Los Roques Archipelago National Park) (Fig. 1). The selection of locations was based on the study of reefs and coral communities located mainly in national parks and other areas where Diadema currently exists.

Method steps

1. Daytime samplings were carried out on different dates, evaluating areas that ranged between 22 and 565 square meters. For this, transects were placed with a variable length that depended on the extension of the coral or rocky community present, as well as the distribution of Diadema populations. The sea urchins were quantified using a 1 square meter quadrant as a sampling unit, which was placed along the transect, spaced according to the size of the evaluated area and the characteristics of the coral or reef community (Table 1). Diadema density was referred to as the number of urchins per square meters.

Specimens wes identified down to species

1. Diadema antillarum
   rank: species

Sampling was undertaken on several shallow-water marine localities on the coast of Venezuela.