Gulf of Mexico Science Volume 18 Article 7 Number 1 Number 1

2000 A Mass Mortality Event in Coastal Waters of the Central Panhandle During Spring and Summer 1998 Sneed B. Collard

Alexis Lugo-Fernandez Minerals Management Service, New Orleans

Gary Fitzhugh National Marine Fisheries Service

John Brusher National Marine Fisheries Service

Rosalie Shaffer National Marine Fisheries Service

DOI: 10.18785/goms.1801.07 Follow this and additional works at: https://aquila.usm.edu/goms

Recommended Citation Collard, S. B., A. Lugo-Fernandez, G. Fitzhugh, J. Brusher and R. Shaffer. 2000. A Mass Mortality Event in Coastal Waters of the Central Florida Panhandle During Spring and Summer 1998. Science 18 (1). Retrieved from https://aquila.usm.edu/goms/vol18/iss1/7

This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf of Mexico Science by an authorized editor of The Aquila Digital Community. For more information, please contact [email protected]. Collard et al.: A Mass Mortality Event in Coastal Waters of the Central Florida P

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Gulf of Mexico Science, 2000(1), pp. 68-71 dissolved oxygen concentrations were, respec­ © 2000 by the ~'Iarine Environmental Sciences Consortium of Alabama tively, 19 C, 35.3, and <1.0 mg·l-1• During low tides on 1-2 July, National Ma­ A MASS MORTALITY EVENT IN COASTAL rine Fisheries Service (NMFS) biologists ob­ WATERS OF THE CENTRAL FLORIDA PAN­ served distressed in St. Andrew State Rec­ HANDLE DURING SPRING AND SUMMER reation Area tidal pools and dead juvenile 1998.-A mass mortality of marine organisms flounders, crabs, and lethargic inside St. occurred on portions of the central Florida Andrew Pass jetties. Dead eels, burrfish, cow­ Panhandle shelf from mid-May through mid­ fish, crabs, starfish, and sea cucumbers were July 1998. Distressed, moribund, and dead fish­ seen on area beaches outside the pass. Dense es and invertebrates were observed from shore concentrations of algae occurred near area to depths of 35 m and were most noticeable beaches on 1-2 July, and large schools of le­ on reefs east and west of Panama City, FL (Fig. thargic Spanish mackerel, baitfish, and sting­ 1). To our knowledge, large-scale, prolonged rays were seen in the shallows at Destin Pass. mass mortalities involving reef-associated ani­ By 3-6 July, water at these locations was re­ mals have not been reported previously in un­ ported to be clear and well mixed. Distressed, impounded shelf waters of the central Florida moribund, and dead fishes and invertebrates Panhandle. continued to be observed from the intertidal zone to about 30 m depth in the St. Andrew Observations.-From mid- to late May 1998, Bay-Destin region until 12 July. Deepwater an­ commercial divers reported mass mortalities of imals were observed at the surface offshore fishes and invertebrates on wrecks and reefs at and in shallow water near shore during this pe­ depths of 10-35 m (the limit of diver excur­ riod. Fishermen reported that highly stratified sions) in a region approximately 3-7 km off­ water, with currents setting to the east, extend­ shore and 20 km east and west of Panama City, ed 24 km offshore. Temperature measure­ FL. At about the same time, fishermen report­ ments on 10 July indicated weak stratification ed blue runners and vermilion snappers float­ in St. Andrew Pass (21 C on the surface; 19 C ing on the surface offshore. According to di­ near the bottom at 12-13 m depth) and a vers, fishermen, and biologists, the areal and strong thermocline 1.6 km offshore (25 C on depth distribution of dead marine co­ the surface; 19 Cat 12-13 m depth). Eastward incided with reports of unseasonably cool wa­ bottom currents extended from 16 to 64 km ter that moved on- and offshore on the surface offshore Panama City, according to fishermen. or beneath a strong thermocline at depths of On 11-12 July, warm ( ~24 C), clear surface 3-12m. water was reported at the Thomas Hayward, a In early June, a dense population of cool­ 26-m-deep wreck off Destin. Nine meters be­ water-tolerant filamentous red algae, Heterosi­ neath the surface, cool, turbid water was en­ phonia gibbesii, occurred along and offshore countered, and at 14m, water temperature was Panama City beaches. Concentrations of H. gib­ 18 C with about 8 m visibility. Near the bottom, besii appeared to move on- and offshore with numerous lethargic fishes were seen at this cool water. Dead fishes and invertebrates were wreck. At the wreck Louise, in 17 m of water, found in algal drifts at St. Andrew Pass and on divers reported that only dead animals were area beaches until the second week of July. In present. On 12July, in the New Pass area at St. late June, divers reported cool water and east­ Andrew Bay, fishermen observed thousands of ward currents at a depth of about 12 m, and small flounder, rock shrimp, penaeid shrimp, large numbers of dead marine animals were and crabs swimming on the surface, and at reported on reefs off Destin, FL, at depths of Destin, live deepwater crabs were observed to 18-21 m. On 1 July, we (GF, JB) reported a be "coming ashore" in large numbers. From strong thermocline at 5-6 m in St. Andrew Pass 13 to 16 July, charter boat captains and divers and observed that all animals seen below 6 m reported cool water inshore, warmer water off­ were dead except for crabs, which were mori­ shore, and dense algae that extended 9-10 km bund. Above the thermocline, fishes normally offshore. associated with deeper water and bottom hab­ During the period 20-23 July, nearshore wa­ itats were seen (Table 1). In bottom water (14 ter in the Panama City area became clearer m) at this location, temperature, salinity, and and surface temperature increased to 27 C

Published by The Aquila Digital Community, 2000 1 Gulf of Mexico Science, Vol. 18 [2000], No. 1, Art. 7 SHORT PAPERS AND NOTES 69

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(NMFS, unpubl.). Mter a shift in winds to the vations of benthic reef assemblages were not east and increasing sea surface temperatures made. (Muller-Karger, 2000; Nowlin et al., 2000), fish­ ermen reported good catches of sharks, Span­ Discussion.-Our observations and anecdotal ish and king mackerel, grouper, snapper, and reports permit a general description of the redfish from Panama City to St. Joseph Bay. time frame, distribution, and magnitude of the According to NMFS and other agency biol­ mass mortality, but we were unable to deter­ ogists, catastrophic mass mortalities on reefs mine causation or assess its long-term ecologi­ progressed from east to west over time. Mor­ cal consequences (see Diaz and Rosenberg, talities on reefs 20 km east of Panama City oc­ 1995). We suggest, however, that unusual cli­ curred in May, whereas reefs west of Destin, matic conditions (Collard and Lugo-Fernan­ but east of Pensacola, experienced mortalities dez, 1999), including westerly surface winds, from June to mid:July. Dead fishes were ob­ large-volume discharges of nutrient-rich fresh served on the surface offshore throughout the water onto the shelf in mid-March, followed by 10-wk period, whereas dead and dying animals record high air temperatures and drought, were most frequently observed on and in the contributed to a stable water column and sup­ vicinity of Panama City area beaches between ported a prolonged bloom of the tropical, 27 June and 12 July. Fishermen reported that cool-water-tolerant alga, H. gibbesii (Pakker et pelagic fishes in the vicinity of affected reefs a!., 1995). Coastal upwelling coincident with appeared normal in abundance and diversity these climatic conditions (Nowlin et al., 2000; by late July (NMFS, pers. comm.), and we ten­ Muller-Karger, 2000) may have contributed to tatively concluded that the mass mortality the bloom of H. gibbesii. We speculate that the event had ended. No systematic sampling of algal population flourished in nutrient-rich dead organisms was made, and the total num­ coastal waters, then died and sank to the bot­ ber of and individuals that perished is tom, increasing biological oxygen demand and not known. Divers avoided areas that experi­ lowering dissolved oxygen concentrations to enced mass mortalities, and follow-up obser- levels stressful or fatal to marine animals (re- https://aquila.usm.edu/goms/vol18/iss1/7 2 DOI: 10.18785/goms.1801.07 Collard et al.: A Mass Mortality Event in Coastal Waters of the Central Florida P 70 GULF OF MEXICO SCIENCE, 2000, VOL. 18(1)

TABLE 1. Fishes and invertebrate groups reported TABLE l. Continued. by various observers to be either dead (D) or visibly distressed (S). No systematic collections were made, Soapfish, Rypticus sp. (D) and the list is conservative, but a question mark fol­ Spariclae lowing a designation means that the most common Pinfish, Lagodon rlwmboides (D) group is supposed. Common names are used when Spottail pinfish, Diplodus holbrooki (D) identification of the species was not verified. Sphraenidae Northern sennet, Sphyraena borealis (D) Fishes U ranoscopiclae Batrachoididae Southern stargazer, Astroscopus y-graecum (D) Gulf toadfish, OjJsanus beta (DIS) Invertebrates Bothidae Annelida polychaetes (D) Bay whiff, Citharichthys spilopterus (D) Arthropoda (Crustacea: Decapocla) Dusky flounder, Syacium papillosum (D) Calico crab, Hepatus epheliticus (DIS) Fringed flounder, Etropus crossotus (D) "Deepwater" crabs (S) Gulf flounder, Paralichthys albigutta (DIS) Pink shrimp (S) Carangidae Portunicl crabs (DIS) Blue runner, Caranx crysos (D) Shrimp, Penaeus sp. (DIS) Leatherjacket, OligojJlites saurus (D) Chordata (Urochorclata: Ascicliacea) Lookdown, Selene vomer (S) Sea squirts (D) Round scad (cigarfish), Decapterus punctatus (D) Cniclaria Carcharhinidae (?) Jellyfish (D) Sharks (D) Echinodermata Dasyatidae Sea cucumbers (D) Stingray, Dasyatis sp. (S) Sea urchins (D) Diodontidae Starfish (D) Striped burrfish, Chilomycterus schoepfi (D) Mollusca Haemulidae Bivalvia: clams French grunt, Haemulon jlavolineatum (D) Cephalopoda: Octopus Pigfish, Orthojnistas cl!l)'soptera (D) Gastropoda: snails; nuclibranchs White grunt, Haemulon plumieri (D) Porifera Labridae Sponges (D) Pearly razorfish, Hemipteronotus novacula (D) Unidentified wrasses (D) Lujanidae Vermilion snapper, Rhombiplites aurorubens (D) viewed in Brongersma-Sanders, 1957; Diaz and Narcinidae Rosenberg, 1995). Low dissolved oxygen con­ Lesser electric ray, Narcine brasiliensis (DIS) centrations may explain the lethargic behavior Ogcocephalidae we observed in fish and crabs (Ogren and Batfish (D) Chess, 1969) and the mass mortality observed Ophichthidae (?) in reef animals. Similar climate and con­ Eel (D) ditions resulted in a mass mortality event in the Ophidiidae Bight (Swanson and Sindermann, Bearded brotula, Brotula barbata (D) 1979). Toxic dinoflagellates were not present Ostraciidae in samples collected and analyzed by the Flor­ Cowfish, Lactophrys sp. (D) ida Marine Research Institute (unpubl. data), R'\iidae and we believe it unlikely that mortalities re­ Skate, Raja sp. (DIS) sulted from thermal stress associated with cool Scaridae water upwelling. Parrotfish (S) Sciaeniclae Acknowledgments.-This study was supported, in Reel drum, Sciaenops ocellatus (S) part, by the Minerals Management Service, Scombriclae Gulf of Mexico OCS Region, New Orleans, LA. Spanish mackerel, Scomberomorus maculatus (S) We thank the following people for their gen­ Scorpaeniclae erous contributions of information: W. Schroe­ Scorpionfish (S) der (Dauphin Island Sea Lab, University of Al­ Serraniclae abama); N. Craft, B. Roberts (Florida Depart­ Gag grouper, iVIycteroperca microlepis (DIS) Gulf black seabass, Centropristis striata (DIS) ment of Environmental Protection); S. Rider, P. Steele (Florida Marine Research Institute);

Published by The Aquila Digital Community, 2000 3 Gulf of Mexico Science, Vol. 18 [2000], No. 1, Art. 7 SHORT PAPERS AND NOTES 71

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https://aquila.usm.edu/goms/vol18/iss1/7 4 DOI: 10.18785/goms.1801.07