Abstract

DOMINGUEZ, Astrid et al. Development, survival and growth of sea urchin Lytechinus variegatus (Lamarck, 1816) (Echinodermata: Echinoidea) fed on microalgae at two different salinities and temperatures. Rev. biol. mar. oceanogr. [online]. 2007, vol.42, n.1, pp. 49-57. ISSN 0718-1957.  doi: 10.4067/S0718-19572007000100006.

Development, survival and growth of Lytechinus variegatus were evaluated until juvenile stage. Thirty two sexually mature specimens were collected in Laguna de Raya (10°89´N, 64°89´O), Venezuela. Sea urchins were induced to spawn by injection of 3 mL of potassium chloride (KCl) 0.5 M. Pluteus larvae were randomly distributed (3 ind mL^-1) in 24 plastic containers, containing 18 L of filtered seawater and with continuous aeration. Containers with the larvae were divided into two groups of 12 containers. One group consisting of six containers with larvae was maintained in seawater with a salinity of 30 psu and the other was kept in seawater with a salinity of 40 psu. Six containers of each salinity were maintained at variable temperature (24-28°C) and the other six at constant temperature (21-23°C). Larvae were fed with the microalgae Chaetoceros gracilis and Isochrysis galbana until they reached the eight arms stage, and additionally, with Tetraselmis chuii from the beginning of the premetamorphic larvae stage (20000 to 40000 cel. mL^-1 for each microalgae). Larval survival was determined daily from four samples of 1 mL of cultured larvae. Growth was controlled every other day, selecting five larvae per treatment. The juvenile stage was attained after 20 days of culture. The experiment was finished after 24 days of culture. During this study neither morphological differences nor growth (until the 8-arms stage) were detected in larvae between treatments. Survival showed significant differences (P<0.05) attaining up to 30% in a combination of I. galbana as food, at a water salinity of 30 psu and at constant temperature

Keywords : Growth; diet; Lytechinus variegatus; survival.