Burkholder, J. M. North Carolina State University, joann_burkholder@ncsu.edu
Glasgow, H. B.
Deamer-Melia, N. J.
Hannon, E. K.

 
THE 1998 FISH KILL SEASON: TRACKING A TOXIC PFIESTERIA OUTBREAK IN THE NEUSE ESTUARY, NORTH CAROLINA, U.S.A.
 
The arrival of large schools of Atlantic menhaden in the eutrophic Neuse Estuary by early July 1998 coincided with moderate salinities (6-8 psu), warm temperatures (28-30oC), and calm weather, conditions favoring outbreaks by the toxic dinoflagellate, Pfiesteria piscicida. We characterized a kill of ca. 500,000 Atlantic menhaden that extended over 12 km2 for 6 days in late July. During the previous 8 weeks and throughout the kill (continuous day/night sampling), DO was > 5 mg/L in the water column of the kill zone, except for hypoxic water (bottom 0.5 m) in areas with depth > 3 m. Other potential causative factors (microcystins, saxitoxins, Vibrio anguillarum, V. vulnificus) were not detected. In an epizootic for 20 days prior to the kill, menhaden developed open bleeding sores (15-25%, coinciding with 150-225 Pfiesteria-like zoospores/mL); and 70% of the fish had lesions during the kill. Fluorescent in situ hybridization and RNA-based probes with confirmed specificity to P. piscicida were used to quantify 250-1,500 zoospores/mL from the upper 1.0 m depth where the kill occurred. Active toxicity by P. piscicida was confirmed from bioassays of water samples with test fish (P. piscicida verified with both molecular probes and SEM of suture-swollen cells). The toxic outbreak was terminated by a severe storm (northeast winds > 70 km/hour) that caused Pfiesteria to leave the water column.
 
Day: Thursday, Feb. 4
Time: 10:45 - 11:00am
Location: Sweeney Center
 
Code: SS10TH1045S