Implications of Glacial Melt-Related Processes on the Potential Primary Production of a Microphytobenthic Community in Potter Cove (Antarctica)

HOFFMANN, RALF; AL-HANDAL, ADIL YOUSIF; WULFF, ANGELA; DEREGIBUS, DOLORES; ZACHER, KATHARINA; QUARTINO, MARÍA LILIANA; WENZHÖFER, FRANK; BRAECKMAN, ULRIKE

FRONTIERS IN MARINE SCIENCE

Frontiers Media SA

Año: 2019 vol. 6

2296-7745

The Antarctic Peninsula experiences a fast retreat of glaciers, which results in anincreased release of particles and sedimentation and, thus, a decrease in the availablephotosynthetic active radiation (PAR, 400?700 nm) for benthic primary production. Inthis study, we investigated how changes in the general sedimentation and shadingpatterns affect the primary production by benthic microalgae, the microphytobenthos.In order to determine potential net primary production and respiration of themicrophytobenthic community, sediment cores from locations exposed to differentsedimentation rates and shading were exposed to PAR of 0?70 mmol photonsm􀀀2 s􀀀1. Total oxygen exchange rates and microphytobenthic diatom communitystructure, density, and biomass were determined. Our study revealed that while themicrophytobenthic diatom density and composition remained similar, the net primaryproduction of the microphytobenthos decreased with increasing sedimentation andshading. By comparing our experimental results with in situ measured PAR intensities,we furthermore identified microphytobenthic primary production as an important carbonsource within Potter Cove?s benthic ecosystem. We propose that the microphytobenthiccontribution to the total primary production may drop drastically due to Antarctic glacialretreat and related sedimentation and shading, with yet unknown consequences for thebenthic heterotrophic community, its structure, and diversity.