Comparative biogeochemistry–ecosystem–human interactions on dynamic continental margins

Abstract

The oceans' continental margins face strong and rapid change, forced by a combination of direct human activity, anthropogenic CO2-induced climate change, and natural variability. Stimulated by discussions in Goa, India at the IMBER IMBIZO III, we (1) provide an overview of the drivers of biogeochemical variation and change on margins, (2) compare temporal trends in hydrographic and biogeochemical data across different margins, (3) review ecosystem responses to these changes, (4) highlight the importance of margin time series for detecting and attributing change and (5) examine societal responses to changing margin biogeochemistry and ecosystems. We synthesize information over a wide range of margin settings in order to identify the commonalities and distinctions among continental margin ecosystems. Key drivers of biogeochemical variation include long-term climate cycles, CO2-induced warming, acidification, and deoxygenation, as well as sea level rise, eutrophication, hydrologic and water cycle alteration, changing land use, fishing, and species invasion. Ecosystem responses are complex and impact major margin services. These include primary production, fisheries production, nutrient cycling, shoreline protection, chemical buffering, and biodiversity. Despite regional differences, the societal consequences of these changes are unarguably large and mandate coherent actions to reduce, mitigate and adapt to multiple stressors on continental margins

Ecosystem function and services provided by the deep sea

“…The concern as to the susceptibility to overfishing of slow-growing and long-lived species of fish and coral in the deep sea is a topic of debate and concern (Bett, 2001;Morato et al, 2006;Althaus et al, 2009). Climate change itself will impact the functions discussed in the deep sea through ocean acidification, declining oxygen and productivity and increasing temperature (Mora et al, 2013;Levin et al, 2014). These impacts are likely to affect the diversity of the supporting functions discussed here, including biodiversity, nutrient cycling, biomass, and primary and secondary productivity .…”

Exploring the Relationship between Macrofaunal Biodiversity and Ecosystem Functioning in the Deep Sea

“…Furthermore, identification of the traits that have a direct and indirect functional role in ecosystems is highly problematic (Pakeman, 2011). The limitations are even greater where deep-sea organisms are concerned, given the poor state of current knowledge regarding their diversity and functional diversity (e.g., Smith et al, 2008;Ramirez-Llodra et al, 2010;Levin et al, 2015).…”

In situ soft sediment nutrient enrichment: A unified approach to eutrophication field experiments

“…This ecosystem service influences the supply and flux of nutrients within and between marine habitats and through denitrification in particular, can alleviate problems such as the loss of ecosystem functionality and biodiversity associated with excess nutrients. Indeed, excessive nutrient loading and eutrophication are stressing coastal marine environments throughout the world (Levin et al, 2015). The overabundance of nitrogen in particular the (nutrient usually limiting production (Herbert, 1999;Howarth and Marino, 2006)) causes changes in biomass, structure, and functioning of coastal communities and food webs (Abreu et al, 2006;Howarth et al, 2011;Rabalais et al, 2014).…”