Zoogeographic Studies at SEA Gain a Wider Audience
Abstract and figure from a poster presented at the 10 th annual Council for Undergraduate Research (CUR), a national scientific conference
Determining the Relationship between Euthecosomatous Pteropod Distribution and Caribbean Water Masses
Skye-Moret Ferguson
During the course of the SSV Corwith Cramer cruise track from St. Croix, USVI, to Key West, Florida (December, 2003), we examined the relationship between pteropod species densities and four Caribbean water masses, Caribbean Surface Water (CSW), Subtropical Underwater (STUW), 18°C Sargasso Sea Water (18SSW) and Tropical Atlantic Central Water (TACW). Geographic location and depth distribution of these four water masses were identified at seven study sites in the Caribbean. Zooplankton nets were towed at three depths to collect pteropods. A sub-surface salinity maximum layer (110-200m) was present at all study sites, indicating the presence of STUW. A sub-surface layer of higher oxygen content (below 200m) was present at three study sites, reflecting the presence of 18SSW in our northern and western Caribbean stations. TACW occurred below 200m at all other stations. More species were found in 18SSW than in TACW. The densities of several pteropod species were correlated with the presence of CSW, STUW and 18SSW. The following pteropods: Cavolinia gibbbosa, C. longirostris, Creseis acicula and Limacina trochiformis were more common in the upper 200m (CSW and STUW). Styliola subula was indicative of 18SSW. These findings suggest that reconstruction of paleoceanographic conditions can be accomplished by examining pteropod remains in sediment cores. The presence or absence of indicator species in successive sediment layers may reveal historic distributions of water masses in the Caribbean Sea.
Nonmetric multidimensional scaling of 20 meter net samples from four Caribbean water masses arranged in environmental space (temperature, salinity, density and oxygen content). Species correlation vectors indicate relationships among net samples and pteropod species: Limacina trochiformis (Ltro), Cavolinia longirostris (Clon), Cavolinia gibbosa (Cgib), and Creseis acicula (Crac).