Vertical distribution of euthecosomatous pteropods in the upper 100m of the Hilutangan Channel, Cebu, The Philippines

The vertical distribution of euthecosomatous pteropods in the upper 100 m of the Hilutangan Channel, Cebu, The Philippines was studied, based on 126 samples, comprising 47, 282 individuals. Thirty-min horizontal plankton tows were performed at depths of 1, 20, 50, 70 and 100 m in January and February 1972. Thirteen species —including 3 subspecies — of juvenile and adult euthecosomes were identified. In decreasing order of abundance the species are: Creseis acicula (20.4%), Limacina trochiformis (19.9%), Creseis virgula constricta (14.6%), L. inflata (10.5%), Clio pyramidata (9.9%), Creseis virgula conica (8.9%), L. bulimoides (7.3%), Diacria quadridentata (5.3%), Cavolinia longirostris (1.9%), Creseis virgula virgula (1.0%), Hyalocylix striata (0.1%), Cuvierina columella (0.08%), Cavolinia uncinata (0.002%). In 3 species, a large percentage were juveniles; for 1 species, Clio pyramidata, only juveniles were caught. The Vertical species distribution was similar to the distribution of the respective species in Caribbean and Bermuda waters. Temperature, salinity and dissolved oxygen influence vertical distribution little, if at all.