BULLETIN OF MARINE SCIENCE, 73(2): 379–396, 2003 379 ABUNDANCE, BIOMASS AND PRODUCTION OF CTENOPHORES AND MEDUSAE OFF KINGSTON, JAMAICA Gale Persad, Russell R. Hopcroft, Mona K. Webber and John C. Roff ABSTRACT The species composition, abundance, biomass, and production of ctenophores and medusae were determined fortnightly from September 1992 to December 1993 in eutrophic waters at the mouth of Kingston Harbour and mesotrophic waters off Lime Cay, Jamaica. The three species of ctenophores, Bolinopsis vitrea, Beröe ovata and Ocyropsis crystallina, occurred at both stations, together averaging 0.82 m -3 in the harbor and 0.60 m -3 at Lime Cay. The ten genera of medusae identified were common to both locations, but their abundances differed considerably, averaging 13.5 m -3 in the harbor and 3.0 m -3 at Lime Cay. In the harbor, Eutima gracilis, Liriope tetraphylla, Ectopleura dumortieri, Cladonema sp. and Clytia sp. all contributed variably to the community without clear seasonality. At Lime Cay, the medusae were equally dominated by Clytia sp. and Liriope tetraphylla. Community biomass was estimated using size-mass relationships established for each of the ctenophores, and the morphologically representative medusae: Eutima gracilis, Liriope tetraphylla and Clytia sp. Ctenophore biomass averaged 663 mg wet-weight m -3 (18 J m - 3 ) at the mouth of Kingston Harbour and 363 mg m -3 (8.4 J m -3 ) at Lime Cay, with Bolinopsis vitrea dominant at both sites. Biomass of medusae at the mouth of Kingston Harbour was 605 mg m -3 (94 J m -3 ), dominated by Eutima gracilis and Liriope tetraphylla. The biomass of the medusae at Lime Cay was 25 mg m -3 (4.0 J m -3 ), dominated solely by Liriope tetraphylla. Production was estimated using growth rates experimentally deter- mined for Bolinopsis vitrea, Eutima gracilis, Liriope tetraphylla, and Clytia sp. Bolinopsis vitrea was the most productive ctenophore at both sampling stations, while for the medu- sae, Eutima gracilis dominated the production at the mouth of Kingston Harbour and Liriope tetraphylla dominated at Lime Cay. The greater proportion of the production of these gelatinous carnivore communities was attributable to the ctenophores in terms of wet-weight (52 and 77%), but not in terms of energetic production (15 and 32%). To- gether their annual production at the mouth of Kingston Harbour was 155 g m -3 yr -1 (13.9 kJ m -3 yr -1 ), while that at Lime Cay was 63 g m -3 yr -1 (3.5 kJ m -3 yr -1 ). Such production would require 36% or more of the combined copepod and larvacean production at these locations. Gelatinous carnivorous zooplankton, such as medusae and ctenophores, are important top predators in many marine environments (e.g., Larson, 1987a,b; Roff et al., 1990; Purcell et al., 1994). Their abundance can alter the community structure and abundance of crustacean zooplankton and ichthyoplankton (Moller, 1984; Behrends and Schneider, 1995; Verity and Smetacek, 1996; Purcell and Arai, 2001). Understanding their variabil- ity on spatial and temporal scales (Graham, 2001; Graham et al., 2001) is vital to predict- ing and modeling these systems (Dalal and Goswani, 2001; Brodeur et al., 2003) and for assessing the effects of human perturbations (Underwood, 1992; Mills, 2001). Surpris- ingly, basic knowledge of the composition, abundance, biomass and production of both medusae and ctenophores is lacking in most marine environments, and this is particularly true in tropical waters.