title: Relationship between spatial distribution of chaetognaths and hydrographic conditions around seamounts and islands of the tropical southwestern Atlantic.
abstract: Relationship between spatial distribution of chaetognaths and hydrographic conditions around seamounts and islands off Northeastern Brazil were analyzed from 133 oceanographic stations during the months of January - April of 1997 and April - July of 1998. Oblique zooplankton tows, using 50 cm diameter Bongo nets with 500µm mesh with a flowmeter to determine the filtered volume, were carried out to a maximum of 200m depth. The Superficial Equatorial Water, which had a salinity > 36 PSU and temperature > 20°C, occupied the top 80 to 200m depth. Below this water mass was the South Atlantic Central Water with salinity ranging from 34.5 to 36 PSU and temperature from 6 to 20°C. The community of chaetognaths showed six species: Pterosagitta draco, Flaccisagitta enflata, Flaccisagitta hexaptera, Pseudosagitta lyra, Serratosagitta serratodentata, and Sagitta helenae. Of these species, F. enflata was the most abundant (32.05% in 1997 and 42.18% in 1998) and the most frequent (87.88% in 1997 and 95% in 1998) during both periods. A mesopelagic specie was identified (P. lyra). This specie was more abundant in 1997 (3.42%), when the upwelling was more intense. P. lyra occurred in 22% of the samples during 1997. The abundance of F. enflata, an epiplanktonic species, increased, associated with greater water-column stability.
authors.affiliation: Laboratório de Plâncton, Departamento de Zoologia, Instituto de Biologia, Universidade Federal da Bahia, Salvador, BA, Brasil.
authors.forename: Christiane S de
authors.initials: CS
authors.lastname: Souza
authors.affiliation: Instituto de Ciências Ambientais e Desenvolvimento Sustentável, Universidade Federal da Bahia, Barreiras, BA, Brasil.
authors.forename: Joana A G
authors.initials: JA
authors.lastname: Luz
authors.affiliation: Laboratório de Plâncton, Departamento de Zoologia, Instituto de Biologia, Universidade Federal da Bahia, Salvador, BA, Brasil.
authors.forename: Paulo O
authors.initials: PO
authors.lastname: Mafalda
mesh_terms: D000818:Animals; D001267:Atlantic Ocean; D018533:Biomass; D001938:Brazil; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D011156:Population Density; D011157:Population Dynamics; D054712:Salinity; D012621:Seasons; D013696:Temperature; D015048:Zooplankton / Q000145:classification*
chemical_list: D002734:Chlorophyll; D000077194:Chlorophyll A