DENSITY MEASUREMENTS FOR BIODIVERSITY STUDIES: THE SPONGE POLYMASTIA JANEIRENSIS (BOURY-ESNAULT, 1973) FROM BRAZIL

Authors

  • GERALD J. BAKUS

Abstract

Studies on the sponge Polymastia janeirensis (Boury-Esnault, 1973) were conducted at an average depth of 3 m on the southeast side of Praia Brava, Buzios, Rio de Janeiro, Brazil during March 4-6, 2001. The sponges measured an average of 17.5 cm x 23.9 cm (oval in shape) and their distribution was moderately aggregated (standardized Morisita Index: 0.49). Densities of P. janeirensis were determined using various methods. Density estimates were as follows: actual count 1.7/m2; stratified random sampling 5.8/m2; point center quarter 0.7/m2; 3rd nearest neighbor 1.6/m2; Weinberg 1.2/m2; Strong-Eberhardt 2.0/m2; and Nishiyama medium 1.1/m2. The method tentatively recommended for estimating densities is the 3rd nearest neighbor, based on preliminary results from this study and other research projects.

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Published

2018-05-22