Very Low Concentrations of Maritime Exhaust Gas Cleaning System Effluent Impair Fertilization and Larval Development in the Green Sea Urchin Strongylocentrotus droebachiensis

Exhaust gas cleaning
systems (EGCS) are increasingly used to meet
IMO sulfur regulations while permitting the continued use of heavy
fuel oil. EGCS effluents are acidic and contain metals, polycyclic
aromatic compounds, and other contaminants that are known to affect
marine organisms. Whole effluent toxicity tests were conducted on
fertilization and larval development of the green sea urchin Strongylocentrotus droebachiensisusing a 0–10%
dilution series of open-loop EGCS effluent. Fertilization success
was significantly reduced at the lowest concentration tested (0.0001%).
Larval abnormalities increased with effluent concentration, reaching
100% at 10% effluent, where larvae failed to develop skeletons and
reach the pluteus stage. Larval growth rates declined with increasing
exposure and ceased at a 10% effluent. Exposure to the lowest test
concentration caused an estimated additional mortality of 4.6% day–1, indicating a high risk of population-level impacts.
As carbonate chemistry remained unchanged below 0.1% effluent, the
toxicity was attributed primarily to contaminants. These findings
indicate that EGCS effluents pose a significant threat to marine life.