Two coral reef sponges were examined in situ off Puerto Rico for fluxes of dissolved inorganic nitrogen. Chondrilla nucula, a ubiquitous Caribbean sponge with cyanobacterial symbionts, releases large amounts of nitrate [600 nmol N g I (dry wt) h-l; 4,000 Mmol N me2 h-l]. Since C. nucula covers a mean of 12% of the substratum, it potentially contributes between 50 and 120% of the nitrogen required to sustain reef productivity. Anthosigrnella varians, a common sponge with zooxanthellae symbionts releases lesser amounts of nitrate [ 19 nmol N g-' (dry wt) h--l; 20 pmol N m-2 h -I]. Alth ough A. varians may cover between 1.2 and 11% of the reef substratum, the potential contribution is < 1% of the nitrogen requiredi For reef productivity. These release rates for C. nucula are comparable to those reported for nitrogen fixation in reef environments and in excess of rates reported for nitrate production by other reef substrata. Large populations of nonphotosynthetic symbiotic bacteria are considered to nitrify amino nitrogen to nitrate and the differences are attributed to the size of bacterial populations and the nature of photosynthetic symbionts.

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Abstract. Long‐term changes in the distributional patterns of commercial sponges (Spongia spp. and Hippospongia spp.) within the West Indian Region indicates that: 1) commercial sponges had a widespread distribution throughout the whole West Indian Region and were ubiquitous in very shallow water until about the first half of the present century; 2) they were fished commercially not only in the traditional northern Caribbean sites (Florida, Gulf of Mexico, Bahamas) but also in the Greater (e. g., Hispaniola, Jamaica) and Lesser Antilles; and 3) they became extinct throughout most of the Lesser Antilles (e. g., Puerto Rico, Vieques, St. Thomas) sometime during the first half of this century. Mortalities of spongiids within the Antilles were found to differ from other marine mortalities in that: 1) species disappeared from a large region; 2) species vanished from different habitats and depths; and 3) natural populations never recovered. Species richness patterns suggest that commercial sponge genera (Spongia and Hippospongia) evolved under slightly cooler elimatic conditions than those found at present, and that these extinctions occurred as a direct or indirect effect of positive thermal anomalies in sea surface and atmospheric temperatures between 1900–1950. The concept that species diversity is stable on a regional scale is questioned.

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Abstract. The morphological variability of thc common Wcst Indian loggerhead spongc, Spheciospongia vesparium, is examined in light of the latcst morphological and ccological information and ncw biochcmical criteria, that is, composition and concentration of fatty acids. A typical and a yellow ecophenotypical form arc distinguishcd. Comparing this species with its next relatives in the same zoogeographical region it is found that S.othella, first describcd from Bcrmuda, cannot be maintaincd as a scparate specics. S. cuspidifera, prcviously misinterprcted as "Xesto5pongia tierneyi", is confirmcd as a distinct spccics of Spheciospongia, whcrcas "Prianos" tierneyi is considercd a morphological variant of S. vesparium. ProblemThe loggerhead sponge Spheciospongia vesparium (LAMARCK) (Clionidae, Hadromerida) and its close relative S. othelia DE LAUBENFELS from Bermuda have been the only recognized species of the genus in the West Indian region up to this time. S. vesparium is a major component of shallow benthic habitats and plays an important role in near-shore ecological processes; it forms patch reeflike bioherms (WIEDENMAYER, 1978(WIEDENMAYER, , 1980 and is an important refuge for juvenile and adult invertebrate and fish populations (PEARSE, 1934; DE LAUBEN-FELS, 1953;WESTINGA & HOETJES, 1981). This sponge usually attains a large size, and in fact has been considered the largest sponge of the world (DE LAUBENFELS, 1950). Specimens of S. vesparium are generally abundant on seagrass beds or