Long-term fluctuations (1974-2010) in the distribution and abundance of Engraulidae eggs and larvae (Teleostei: Clupeiformes) at the Southeastern Brazilian Bight

Abstract

Ichthyoplankton study contributes to several areas of biology and fisheries science. Composition and abundance of fish eggs and larvae are strongly influenced by physical processes. On the Brazilian coast, studies focusing on long-term environmental factors relating to the distribution and abundance of ichthyoplankton are nonexistent. Therefore, the main objective of this project is to evaluate inter-decadal fluctuations in the distribution and abundance of larvae and eggs of Engraulidae (Teleostei: Clupeiformes) in the Southeastern Brazilian Bight, examining whether those fluctuations may be related to oceanographic factors (eg. salinity and temperature) and climate variability (e.g. El Niño). In addition, using the spatial analysis of the anchovy eggs over the years, we intend to infer spawning sites and if those sites have changed over time. To achieve these objectives we will analyze data from 18 oceanographic cruises that occurred during summer months from 1974 to 2010 in the Southeastern Brazilian Bight, totaling 1,464 samples. Ichthyoplankton were collected by oblique hauls using a bongo nets coupled with a flow meter. Temperature and salinity data were obtained from Nansen bottles and reversing thermometers until 1988. After this date, we used a CTD. Additional abiotic data, as the presence or absence of climate anomalies (e.g. occurrence of El Niño in a given year) will be obtained through specialized web pages. (AU)