PELAGIC CONTAMINATION

The continue pressure for expanding oil exploration in the outer continental slope in the past decades has increased the risk of catastrophic discharges of oil and gas into the marine environment. The Deepwater Horizon oil spill with discharges of 600,000 tons of oil and 260,000 of tons of gas into the northeastern Gulf of Mexico demonstrated a worst-case scenario disaster. Originated at depth (1,500 m) over a large area from coastal to pelagic zones caused deleterious effects in natural ecosystems, which some have not yet fully recovered. In addition, this disaster highlighted the paucity of baseline chemistry data for deep-ocean ecosystems worldwide. Without baseline information on hydrocarbon dynamics in pelagic organisms, the assessment of impacts from oil exploration and activities is very difficult or nearly impossible. Our work includes performing geochemistry analyses of contaminants by GC-MSMS to establish a time series of polycyclic aromatic hydrocarbons (PAHs) in pelagic fauna collected from mesopelagic and bathypelagic depths in the Gulf of Mexico. This study will provide baseline data to estimate levels of PAH exposure and its potential effects in deep-pelagic communities.

Preliminary Results from 2015:

- Fish species:

Ceratoscopelus warmingii, Argyropelecus aculeatus, and Sigmops elongatus

- Shrimp species:

Acanthephyra purpurea

- Cephalopods:

Grimalditeuthis bonplandi, Histioteuthis corona, Japetella diaphana

 

 - Low concentrations in 2015, suggests recovery of deep pelagic communities


- Higher concentrations in gut samples indicate food is the primarily source of PAHs


- Large spatial variability of PAHs denotes the importance of large-scale sampling for assessment of impacts