TP21 Assessment in Tropical Ecosystems
Tuesday, 15 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(CAR-1116-949448) Toxic effects of African dust in Caribbean waters.

Carr, R.¹, Nipper, M.², Garrison, V.³, ¹ USGS, MERS, Corpus Christi, TX, USA² TAMU-CC, Corpus Christi, TX, USA³ USGS, St. Petersburg, FL, USA

ABSTRACT- The transport of dust from the African Sahara and Sahel to the Americas via the Saharan Air Layer has been occurring for millennia, but the production, use and release of man-made organic chemicals into the environment is a relatively recent phenomenon. Land use changes in Africa may also contribute to the transport of larger amounts of dust. Therefore, the quantity and quality of dust transported in recent decades and reaching downwind ecosystems may have changed. It is hypothesized that contaminants associated with African dust are contributors to the decline of coral reefs in the Caribbean. The current project has the objective of testing this hypothesis. Toxicity assessments were performed with seawater elutriates of African dust collected in the U.S. Virgin Islands, using the sea urchin Arbacia punctulata early life stage tests, the copepod Schizopera knabeni survival and hatching success test, and the polychaete Dinophilus gyrociliatus life cycle test. All experiments indicated elevated toxicity of several dust elutriates and toxicity identification evaluation (TIE) procedures identified metals as the toxic agents. However, the level of contamination of marine environments due to dust input is not clear. Toxicity tests are underway using several types of marine samples collected under dust and no-dust conditions: sea surface microlayer, subsurface seawater, water from coral interstices and porewater from areas adjacent to coral reefs. Results and their implications for coral reef ecosystems will be discussed.

Key words: African dust, toxicity, TIE, Caribbean