FUMAROLES & FORAMINIFERA: CHRONICLING EFFECTS OF DECREASED PH ON BENTHIC FORAMINIFERA OF DOMINICA

Significant CO₂ seepage due to volcanic activity has been documented within the shallow waters of Dominica, a small Caribbean island of the Lesser Antilles. In one location, fumaroles bubble up so readily from the seafloor that divers have given it the name Champagne Beach. This nearshore environment is a prime location to examine the effects of increased CO₂ on calcifying marine organisms, including foraminifera. Increased absorption of CO₂ by the oceans has already begun in response to climate change, and Champagne Beach provides a unique location to measure localized pH and document the potential effects of increased acidity on benthic foraminiferal communities.

Modern seafloor samples were collected at two locations within the Soufriere Scotts Head Marine Reserve: Scotts Head, representative of a typical Caribbean nearshore reef environment, and Champagne Beach, a nearshore reef within active fumaroles. Initial investigation of samples from Scotts Head, the control site with an average pH of 8.13, contain abundant benthic foraminiferal of several genera. Conversely, samples from Champagne Beach (pH at fumarole = 7.75) are essentially devoid of calcareous foraminifera and contain only fragments of broken agglutinated tests. Measurements of pH indicate that acidity varies considerably, appears to be dependent upon the presence of fumaroles, and has considerable influence on benthic foraminifera. These findings are consistent with assemblage changes described from volcanic gas vents in the Mediterranean, and suggest volcanism has significant impacts on benthic foraminiferal populations in the shallow waters of Dominica. Additionally, these localized results illustrate how ocean acidification will likely impact benthic foraminifera populations globally.