The Effect of Cold and Warm Anomalies on Phytoplankton Pigment Composition in Waters off the Northern Baja California Peninsula (México): 2007–2016

Adriana González-Silvera,Jonatan Santander-Cruz,Eduardo Santamaría-Del-Ángel,Jorge López-Calderón,Víctor Camacho-Ibar,Alfredo Mercado-Santana

doi:10.3390/jmse8070533

Abstract

In this study, we report the response of phytoplankton community composition to cold and warm interannual events affecting the waters off the Baja California Peninsula from 2007 to 2016 based on data obtained from a single marine station (31.75° N/116.96° W). Included variables were satellite chlorophyll a, sea surface temperature (MODIS/Aqua), upwelling intensity, and field data (phytoplankton pigments, inorganic nutrients, light penetration). Phytoplankton pigments were determined by high performance liquid chromatography, and CHEMTAX software was used to determine the relative contributions of the main taxonomic groups to chlorophyll a. Our results confirm the decrease in phytoplankton biomass due to the influence of the recent Pacific Warm Anomaly (2014) and El Niño 2015–2016. However, this decrease was especially marked at the surface. When data from the entire water column was considered, this decrease was not significant, because at the subsurface Chla did not decrease as much. Nevertheless, significant changes in community composition occurred in the entire water column with Cyanobacteria (including Prochlorococcus) and Prymnesiophytes being dominant at the surface, while Chlorophytes and Prasinophytes made a strong contribution at the subsurface. Analysis of the spatial distribution of SST and satellite chlorophyll a made it possible to infer the spatial extension of these anomalies at a regional scale.

Highlights

Phytoplankton comprise the main primary producers in the ocean worldwide and play a fundamental role in aquatic ecosystems
Significant changes in community composition occurred in the entire water column with Cyanobacteria and Prymnesiophytes being dominant at the surface, while Chlorophytes and Prasinophytes made a strong contribution at the subsurface
ChlaSAT showed a clear seasonal pattern (Figure 2a), with maximum positive anomalies being observed between March and June

Summary

Introduction

Phytoplankton comprise the main primary producers in the ocean worldwide and play a fundamental role in aquatic ecosystems. Recent studies based on satellite-derived chlorophyll data have shown a global phytoplankton decline over the last century [3,4] that has been associated with global warming and an increase in stratification that isolates surface waters from cool, nutrient-rich deeper water [3] This has been suggested to be a potential mechanism altering phytoplankton community composition through an increase in the proportion of small-sized groups [5,6], with consequences in higher trophic levels and fisheries [7]. Positive wind stress curl generates Ekman pumping that brings the CUC to the surface [8] These processes determine the variability of phytoplankton biomass and community composition [10,11], as well as the biomass of organisms at higher trophic levels [12]. Cold events promote the shallowing of the nutricline, as well as high phytoplankton biomass and primary production, favoring diatom growth [10,16]

Methods

Results

Conclusion