The stable isotope composition of planktonic foraminifera correlates with evidence for pulses of terrigenous sediment in a sediment core from the upper continental slope off northeastern Brazil. Stable oxygen isotope records of the planktonic foraminiferal species Globigerinoides sacculiferand Globigerinoides ruber(pink) reveal sub-Milankovitch changes in sea-surface hydrography during the last 85,000 yr. Warming of the surface water coincided with terrigenous sedimentation pulses that are inferred from high XRF intensities of Ti and Fe, and which suggest humid conditions in northeast Brazil. These tropical signals correlate with climatic oscillations recorded in Greenland ice cores (Dansgaard-Oeschger cycles) and in sediment cores from the North Atlantic (Heinrich events). Trade winds may have caused changes in the North Brazil Current that altered heat and salt flux into the North Atlantic, thus affecting the growth and decay of the large glacial ice sheets.

The brittle stars Ophiactis savignyi and Ophiothela mirabilis are documented for the first time from French Guiana. The latter species was associated with colonies of a gorgonian, Leptogorgia miniata, growing on a rocky reef beneath a brackish layer of water and above an unstable mud bottom. Ophiothela mirabilis is a recently established alien introduction to the Atlantic. Ophiothela discovered in French Guiana were located approximately midway between populations of O. mirabilis in Brazil and at St Vincent, and individuals from all three countries may represent a single lineage of ophiuroids. Evidence is presented that O. savignyi and O. mirabilis could have been transported to the Amazon Barrier region by shipping and/or by coastal currents linking Brazil, French Guiana and St Vincent. If oceanic circulation is responsible for its dispersal, it is predicted that O. mirabilis will spread from the Windward Islands toward the southern Caribbean coast, whereas dispersal by shipping could follow a more northerly route.