The continued pressure to expand the exploration of natural resources in the past decades has increased the risk of environmental impacts with little understanding of ecosystem resilience. The Marine Organic Chemistry lab at USC focuses on identifying chemical signatures that can be used as indicators of ecosystem change, from coastal to deep-sea demersal environments, including pelagic and benthic systems and their living biota.

One of the main challenges is to link physical, chemical, and biological components in large-scale ecosystems when little information is available. For example, the deep-pelagic is both the Gulf of Mexico’s largest habitat and least known, highlighted by the Deepwater Horizon oil spill, due to the extensive data gap that hampered the assessment of injury to the environment. Still, a decade after the spill, information regarding the source and weathering of organic matter and associated organic contaminants is mostly unknown. Organic contaminants can alter biological diversity and ecosystem functioning, therefore are key for linking long-term population dynamics and environmental stressors.

Assessing marine ecosystems functioning and health requires multiple tools.  In the Marine Organic Chemistry lab we apply different organic chemical analyses (e.g., aromatics, alkanes, persistent organic pollutants) in combination with stable isotopes (e.g., carbon, nitrogen) to contrasting environments and biotic systems. Current projects cover three principal lines of research (for detailed information, see the the “Projects” tab):

• Sources, transport, and fate of chemicals on the ocean floor: Sediments containing ubiquitous organic molecules are influenced by natural and anthropogenic processes during their transport in the water column before deposition. Thus, the seafloor serves as a repository for a wide range of molecules that can be used to assess recent and historical geochemical processes as well as impact events. 
  
• Time-series analysis of toxic compounds in shallow and meso/bathypelagic fauna: The consistent and systematic recording of observations over time is essential for distinguishing natural variability from ecosystem change. Ecosystem-based management of the oceans relies strongly on continuous observations for establishing baselines. The Deepwater Horizon spill highlighted the lack of available baseline data for marine ecosystems in the Gulf of Mexico and elsewhere. Given the constant drive toward the exploration of natural resources, the persistent contribution of land-derived pollutants, and ongoing climate change impacts, more studies need to assess the acute and chronic effects of impact activities on marine fauna. 
• Chemical indicators of ecosystem health: Ecosystem indicators are quantitative measurements that serve as proxies for the conditions of a natural system. Integrating biological factors and ecosystem functions (e.g., community structure, primary productivity, currents) with chemistry (e.g., oxidation products, xenobiotic chemicals) provides a better representation of the health of an ecosystem, particularly after extreme impact events.

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