ESSI seminar - Mustafa Yucel

Mustafa Yucel, Middle East Technical University

‘From expanding anoxia to recent sea snot events: Biogeochemical transformation of the connected Black Sea - Marmara Sea System in response to multiple stressors’

This week's virtual visitor is Mustafa Yucel from Middle East Technical University. Mustafa Yucel leads the Deep Sea Research Group at METU-IMS which consists of chemists, geologists, and biologists working on different topics covering marine biogeochemistry, hydrothermal geochemistry, and microbial ecology. In particular their research includes the biogeochemistry of low-oxygen marine environments and deep-sea chemosynthetic ecosystems.

Register to attend here.

Abstract: Study of marine redox gradients have gained significance in recent years due to their increased interlinkages to global metal and nutrient element biogeochemical  cycling via expanding low-oxygen zones in oceans. Hypoxic and anoxic basins in semi-enclosed regional seas can serve as models of how the global low-oxygen seas and ecosystem services therein will respond to the multiple interplay of climate change, anthropogenic inputs and natural variations.  Here I will review the latest biogeochemical redox cycling in the Black Sea and Marmara Sea - two basins connected via Bosporus strait, both being strongly stratified but remaining distinctly different in their redox response to multiple stressors. The Black Sea is a largely anoxic-sulfidic basin with a relatively stable suboxic zone where trace metal redox cycles are long thought to maintain the buffering of climate and anthropogenic stressors introduced to the upper, oxic layer zone. This may be changing as the upper layer loses its oxygen and the suboxic zone becomes less efficient in filtering the hydrogen sulfide of the deeper layers. The Marmara Sea is an estuary-like basin, with the deeper waters progressively showing oxygen loss and seasonal accumulation of hydrogen sulfide, as a result of mostly anthropogenic nutrients introduced to the basin in the last decades.  Both seas demonstrate unique redox-dependent feedbacks linking oxygen, metal, nitrogen and phosphorus cycles and these new links can inform new paleoceanographic models that try to better represent relationships between past biogeochemical cycles under fluctuating stressors including climate change.