Changes in phytoplankton in the Peruvian sea, summer 2017. Cruise 1703-04, R/V Jose Olaya and R/V Luis Flores

Abstract

This paper makes it possible to know plankton volumes (mL.m-3), composition, densities, phytoplankton distribution, as well as biological indicators for water mass in summer 2017 when oceanographic conditions were influenced by the El Niño Costero. A total of 183 samples collected with standard phytoplankton net, and 25 samples, which were obtained with Niskin bottles at a depth of 10 m, were analyzed. The mean plankton volume was 0.68 mL.m-3 ranging between 0.045 and 12.82 mL.m-3, which were located off Punta La Negra and Huacho, respectively. Phytoplankton predominance was 37%, integrated by diatoms in the first stages of phytoplankton succession, including Chaetoceros spp., Ditylum brightwellii, Skeletonema costatum, Coscinodiscus spp., Thalassiosira subtilis, and Lithodesmium undulatum. At latitude level, plankton recorded mean values between 0.045 mL.m-3 (11-12°S) and 2.71 mL.m-3 (16-17°S), outside 60 nm and between 30- 60 nm, respectively. It was evident the increase in density of the phytoflagellate group (673x103 cel.L-1). Protoperidinium obtusum, an indicator of Cold Coastal Waters (CCW), was distributed along the coast within 40 nm and with greater incidence in the southern zone (Pisco - Callao). Keywords: phytoplankton, composition, abundance and distribution, biological indicators, summer 2017