FSA Partnership Meetings:
October 4: Panhandle Working Group in Panama City. Contact FSA Coordinator.
October 4: Suncoast Partnership, 12-2 pm, Eckerd College. Contact Beth Forys.
October 4: Volusia Partnership, 9am-12pm, Beach Safety HQ, Daytona Beach. Contact Jennifer Winters.
October 9: Lee/Collier Partnerships, 1-4:30 pm, Rookery Bay ELC. Contact Adam Dinuovo.
October 10: Southeast Partnership, 1-3pm, location TBD. Contact Natasha Warraich.
October 11: St. John's/Flagler Partnership, 1-4pm, St. Augustine Alligator Farm. Contact Chris Farrell.
October 15: Florida Keys Partnership, 1-3pm, Marathon Gvt. Center. Contact Tom Sweets.
October 22: Treasure Coast Partnership, 1-3pm, Savannas Preserve State Park. Contact Dan O'Malley.
October 23: Timucuan Partnership, 10am-1pm, Ribault Club, Jacksonville. Contact Blair Hayman.
October 25: Nature Coast Partnership, 1-4pm, Withlacoochee Gulf Preserve (new location). Contact Megan Wallrichs.
October 25: Space Coast Partnership, 10am-12:30pm, Kiwanis Island Park, Merritt Island. Contact Anna Deyle.
Events:
October 1: Florida Shorebird Data Entry Deadline
October 11-14: Florida Birding & Nature Festival
October 19-20: Florida Audubon Assembly
FSA News
Special Report: Red Tide and Birds
Michelle van Deventer
For most of this year, coastal areas of southwest Florida have been experiencing a severe harmful algal bloom (HAB, or “red tide”). The species responsible for these conditions is Karenia brevis, a microscopic marine dinoflagellate. Karenia brevis is named for FWC-FWRI scientist Dr. Karen A. Steidinger in recognition of her research on the organism and associated blooms.
Karenia brevis is primarily found in the Gulf of Mexico along the West Florida Shelf. Physical factors, such as upwellings and currents, play a significant role in the initiation and propagation of blooms. Most blooms begin offshore away from inputs of coastal nutrients, and transport is largely influenced by physical and chemical conditions, such as wind, currents and salinity. Blooms have occasionally been transported by the Loop Current and Gulf Stream from the Gulf of Mexico to the east coast of Florida, as far north as the mid-Atlantic.
Blooms of K. brevis have been historically reported in the Gulf of Mexico since the mid-1800’s. Formal investigations began more than 50 years ago, and localized, short term blooms have been documented almost annually. Larger or more intense blooms have occurred on a cycle of every 3–5 years. Blooms of extreme intensity are described in literature from the 1940s, 1970s, 1990s, and most recently during an event in 2005-06. The 2005-06 event lasted over a year, impacted almost the entire west coast of the state, and resulted in a 2,000 square mile “dead zone” of hypoxic and anoxic water.
Karenia brevis produces a suite of toxins known as brevetoxins, of which there are over a dozen metabolites or derivatives of varying toxicity. Brevetoxins are potent neurotoxins that bind to the sodium channels of nerve and muscle cells, causing them to become “hyperactive”. Neurotoxic Shellfish Poisoning (NSP) is caused when people consume shellfish that have filter-fed toxic K. brevis cells and internally stored the brevetoxins. The State of Florida monitors shellfish beds during red tides and manages them accordingly to prevent NSP incidents. Brevetoxicosis is known to cause illness and death in invertebrates, fish and wildlife, including marine mammals, sea turtles, and birds. Land animals, such as raccoons and coyotes, have also been sickened after consuming red tide-killed fish washed up onshore. Birds may be exposed to toxins through their diet or suffer from reduced prey availability during extended bloom conditions. Red tide conditions may also leave birds more vulnerable to other threats, such as parasites or migratory exhaustion.
The fate and effects of brevetoxins in the food web are complex and continue to be investigated by FWRI’s HAB lab. Not all species are affected equally, and there are often lag-times between the onset of bloom conditions and observed mortality or morbidity in wildlife. Debilitated or dead fish-eating birds, such as cormorants, pelicans and gulls are typically reported in the greatest numbers during a red tide. But the timing of the blooms can be a key factor in impacts to birds. A bloom that coincides in timing and location with migration may result in a single-species mortality event. This was observed in 1974 when thousands of dead and dying lesser scaup were collected during a red tide in Tampa Bay. Although highly circumstantial, brevetoxicosis was not proven at the time.
Signs of red tide poisoning in birds can vary by species, but generally include a lack of coordination, failure to fly or stand when approached, and a head tremor or droop. Seabirds and wading birds are most likely to be exposed to chronic or acute levels of brevetoxins through their diet as prey fish can internally accumulate toxins. Some wading birds and seabirds may be able to avoid toxin exposure or respond to reduced prey availability by foraging at freshwater sites. For shorebirds, common prey items such as bivalves and mole crabs can transmit the toxins to birds. Die-offs of these organisms have also been documented during intense blooms. Sandpipers, such as sanderlings and ruddy turnstones, are frequently observed scavenging red tide-killed fish beached on the shore which can also be a source of toxins. Plover species are less frequently observed scavenging dead fish and may switch to mostly insect prey such as beetles and flies.
Perhaps one of the most interesting findings about the history of red tide impacts to birds in Florida occurred in 1989 when a fossil assemblage of marine birds and fish was discovered at a shell excavation pit in Sarasota County that was dated to the late Pliocene (approximately 2 million years ago). The avian fossils were dominated by a single species of extinct cormorant, Phalacrocorax filyawi. Fossils of several other bird species, as well as an extinct species of seal, were also uncovered. Throughout the fossil layers were thousands of bones and scales of marine fish, as well as “abundant cysts of a dinoflagellate species known to produce toxic red tides”, leading to the conclusion that a series of HABs in the Gulf were the source of the mortality. Although K. brevis is not known to produce a cyst, the implicated toxic dinoflagellate, Pyrodinium bahamense, is still present in Florida waters to this day, and can also be responsible for food poisoning incidents and fish and wildlife mortalities.
While red tides have occurred in Florida since before modern development and many blooms initiate offshore away from coastal nutrient sources, K. brevis can use natural and man-made nutrients once present along shore. Efforts to support healthy beaches and coastal areas can help address other threats to wildlife and water quality that may worsen the impacts of red tide or inhibit the ability of populations and systems to recover. Recent investigations into the potential impact of climate change, including ocean acidification and rising temperatures, have suggested that future climate conditions could also worsen K. brevis blooms.
If you find a sick bird during a red tide, or at any time, find the closest licensed rehabber by using the FWC Seabird Rehabilitator App online or Download the App to your SmartPhone. Observations of dead birds, either unusual species or cluster of multiple birds in proximity, can be reported to the Wild Bird Die-off Surveillance website or the FWC Reporter App.
If you are a rehabber and need more information, contact Lisa Shender at FWC-FWRI Wildlife Health or Michelle van Deventer.
FSD Updates
Ebb Tidings
Christopher Lipps of Audubon Florida calmly works to free two pelicans from fishing line entanglement. Both birds were successfuly freed thanks to the work of local shorebird biologists.
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The Florida Shorebird Alliance (FSA) is a partnership of agencies, non-government organizations, and individuals committed to shorebird and seabird conservation in Florida. FSA partners coordinate their independent work and collaborate to address research, management, education, outreach, and public policy needs.
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