Prokaryotic picoplankton distribution within the oxygen minimum zone of the central Mexican Pacific across environmental gradients

Abstract

Marine picophytoplankton has become an important issue to understand the global ecology of phototrophic forms, due to its wide distribution and contribution to biomass and productivity. We studied the abundance, distribution and signature pigments of the prokaryote picophytoplankters Prochlorococcus and Synechococcus during an oceanographic cruise (26 April to 7 May, 2011) in the central Mexican Pacific, a relatively poorly-known oxygen minimum zone (OMZ), and the effect of three environmental gradients. Prochlorococcus and Synechococcus abundances were comparable with those found in other tropical areas (0.17 to 30.37 X 104 cells mL-1, and 0.9 to 30.97 X 104 cells mL-1, respectively). Prochlorococcus abundances reached highest numbers in deeper waters, often coinciding with the second deep in situ fluorescence (and chlorophyll α) maxima, at oceanic stations, below the nitratecline, whereas Synechococcus abundances were higher at subsurface waters and its concentration maxima usually coincided with the subsurface in situ fluorescence maxima, with slightly higher abundances in coastal stations. Statistical analyses support significantly these results. Distribution of divinyl-chlorophyll α was erratic along the water column and occasionally coincided with the deep in situ fluorescence maxima, whereas the distribution of zeaxanthin usually followed that of chlorophyll α and the abundances of Synechococcus, and peaked together. These results are similar to those previously found in the study area and in more temperate zones, and also to the general trend in OMZ, but confirm that the second deep chlorophyll α maxima are attributed to high Prochlorococcus densities. We additionally found the abundance and distribution of Prochlorococcus and Synechococcus strongly driven by the environmental gradients observed.

Picocyanobacteria in Surface Water Bodies

“…There are different molecular techniques used for the identification of picocyanobacteria, in this review we found that the application of these techniques to characterize and amplify portions of the cyanobacterial genome has increased considerably in recent years. These techniques have proven to be valuable for comparing the structures of complex microbial communities, inferring phylogenetic relationships, and monitoring their dynamics in relation to environmental factors [32]. Cyanobacteria such as Synechococcus and Cyanoothece are particularly difficult to identify and classify [33], most molecular methods to identify them are based on total DNA or RNA extraction and amplification by PCR as shown in Table 3.…”

“…It inhabits the entire photic zone and can be found as deep as 200 m below the surface, being abundant in oligotrophic systems [43]. Prochlorococcus and Synechococcus can coexist in water bodies, but Synechococcus tolerates a wider temperature range, without being limited by temperatures as low as 2°C and is more ubiquitous and has a wider latitudinal distribution [32].…”

Implicaciones de la profundidad de la zona eufotica e irradiancia de compensación sobre la productividad primaria en Cuenca Alfonso, BCS, Mexico.

“…Al respecto, Hakspiel-Segura, (2014) registró un incremento estacional similar en la productividad primaria en profundidades cercanas a la de compensación en donde el picoplancton suele incrementar su productividad. Santana-Vega et al (2018) reportaron que la fracción picofitoplanctónica tuvo mayores concentraciones de clorofila a en la zona profunda, mientras que Marquez-Artavia et al…”