ABSTRACT

Radiolaria have been collected and identified from the water column and from Holocene sediments of the Gulf of Mexico and adjacent waters using Nansen closing nets, DUCA high speed nets, gravity cores and box cores. Radiolarians in the water column and the sediments can be used as indicators of horizontal and vertical water movements, degrees of eutrophism and oceanographic seasonality.

Most radiolarian species appear to be indicative of one or more water masses that enter the Gulf of Mexico through the Yucatan Passage; none of the identified species are endemic to the Gulf of Mexico. Living radiolarian diversities and densities are now in the waters over the Texas continental shelf and in the oligotrophic open Gulf of Mexico in comparison to the oligotrophic open ocean Sargasso Sea and the boundary currents off Florida and southern California.

The nature of the empty radiolarian test assemblage in the water column suggests that radiolarians in Recent sediments settle to the sea floor as individual tests and by fecal pellet and/or organic aggregate sedimentation. Although poor radiolarian preservation presently characterizes the Gulf of Mexico and the mid- and low-altitude Atlantic, the most ideal radiolarian preservation in the world oceans today may be in the Orca basin in the northwestern Gulf of Mexico.

Living radiolarian studies can be applied to the paleontologic record in order to: understand the development of the thanatocoenosis; trace the initiation and extent of paleo-water masses; establish paleo-temperature curves; investigate paleo-eutrophy and infer paleo-niches; and develop a cosmopolitan biostratigraphy.