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 > 20ºC, 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.

The influence of environmental conditions onParasagitta friderici(Chaetognatha) abundance in a subtropical estuary (south Brazil)

“…The influence of physical and biological environment on chaetognath populations and their spatial and temporal dynamics from shelf and oceanic ecosystems is relatively well-known, with many available studies on the South-western Atlantic (e.g. Crelier & Daponte, 2004; Araújo & Ribeiro, 2005; Souza et al ., 2014) and in most other main regions worldwide (e.g. Gibbons & Stuart, 1994; Nair et al ., 2002; Ruiz-Boijseauneau et al ., 2004; Noblezada & Campos, 2012; Wu et al ., 2014).…”

Genetic diversity and connectivity of Flaccisagitta enflata (Chaetognatha: Sagittidae) in the tropical Atlantic ocean (northeastern Brazil)

“…Among the cosmopolitan species of Chaetognatha, Flaccisagitta enflata (Grassi, 1881) was selected as model for this study due to its extensive horizontal distribution and high abundance in marine plankton. This species can reach lengths of up to 25 mm in the adult stage and presents a typical occurrence in epipelagic waters of the tropical and subtropical regions throughout the world [2,[13][14][15], including neritic and oceanic areas of northeastern Brazil, where it is usually the most abundant species of the phylum [16][17][18]. Its distribution based on conventional taxonomic identification is, therefore, well documented in the literature.…”

Distribución espacio-temporal y abundancia de quetognatos en El Hierro (islas Canarias)

“…Los datos de fluorescencia (figura 2), que se relacionan con la cantidad de clorofila, coinciden con estos valores de abundancia, aumentando en campaña de 2014 (figura 4), lo que se puede traducir en un incremento de la actividad del fitoplancton y, por consiguiente, un aumento en la cantidad de presas que consumen a estos productores primarios. Por tanto, los valores de fluorescencia afectan a la abundancia de quetognatos, como ocurre en trabajos similares (Souza et al, 2014).…”

“…La menor abundancia de Flaccisagitta enflata en marzo de 2013 frente a valores ligeramente superiores de Flaccisagitta hexaptera con respecto al mismo periodo del año 2014, puede tener su explicación, entre otros factores, al presentar estas especies distintas afinidades por los niveles de clorofila según estudios para el Atlántico occidental (Souza et al, 2014), siendo F. hexaptera dependiente de valores superiores respecto a F. enflata. Sin embargo, en este estudio parece ocurrir lo contrario.…”