Spatial patterns of large jellyfish Chrysaora plocamia blooms in the Northern Humboldt Upwelling System in relation to biological drivers and climate

Abstract

In the Northern Humboldt Upwelling System (NHUS), one of the most productive ecosystems in the world, the large jellyfish Chrysaora plocamia exhibits high inter-annual variability in population size, often resulting in massive blooms. In this study, we examined the geographic patterns C. plocamia in the NHUS and their spatial overlap with ichthyoplankton, zooplankton, and chlorophyll a concentration (Chl a) during two El Nino (EN) years (1982-1983 and 1986-1987), and a neutral year (2014). During EN years, the spatial extent of ∼ C. plocamia medusae was larger than in the neutral year. In 1982-1983, medusae were concentrated mainly in the central-southern and southern regions of Peru, where they were associated with zooplankton, sardine larvae, and Chl a. In 1986-1987, medusae occurred in the northern and southern regions and spatially overlapped with sardine larvae and Chl a, and with zooplankton and anchoveta larvae, respectively. In 2014, medusae occurred mainly in the northern region, where they were associated with zooplankton, Chl a, and anchoveta eggs and larvae. Our results indicate strong EN effects on the distribution and abundance of C. plocamia, which can have consequences for zooplankton and ichthyoplankton abundance, as well as fisheries, in the NHUS.