HEALTH STATUS OF FORAMINIFERAL POPULATIONS IN NUECES BAY, TEXAS

Replicate cores were taken at five stations in Nueces Bay, Texas to evaluate the health of living foraminifera in this heavily impacted estuary. A shallow secondary bay, Nueces Bay is naturally stressed and receives point source and non-point source effluents from the Nueces River and various industries. Most of the industries, including oil refineries and manufacturing plants, are clustered on the south shore of the bay, which also has a power plant and a shipping channel. The north shore, in contrast, is nearly devoid of industry and habitation. Since salinities in the bay vary due to fresh water influence, foraminiferal populations were sampled mid-bay on a north-south transect where conditions are most constant. Preliminary results show that living densities are higher at the southernmost stations, perhaps as a result of increased nutrient levels and seawater discharge from the power plant. Population numbers in Nueces Bay are similar to those reported in the 1950s for other central Texas Bays, and thus appear to be stable. Also noteworthy is that a high percentage of living foraminifera, mostly Ammonia, exhibit damaged tests. In the damaged individuals several outer chambers are typically missing, but sometimes an entire outer whorl is gone. The primary factors involved with shell loss are not yet understood. Presence of extensive framboidal pyrite in dead tests and in sediment indicates that reducing conditions are common on the bottom.