Since the beginning of April, the Santa Barbara Wildlife Care Network has been inundated with gravely ill pelagic birds. Pelagic birds spend their lives in the ocean and are therefore particularly susceptible to domoic acid, a neurotoxin produced by a certain type of plankton known as Pseudo-nitzschia. During April alone, the Wildlife Care Network staff and volunteers had cared for 216 sick pelagic birds, mostly loons, grebes, and murres. By comparison, fewer than ten pelagic birds were brought to the center for rehabilitation in the previous two months.
The general public in Santa Barbara and Ventura counties have noticed a change in wildlife behavior over the past few months as well, observing scores of pelagic birds, which normally stay in the water, beaching themselves. Pelagic birds typically land on beaches only if they are injured, ill, or severely malnourished. Research has confirmed that the current increased incidence of beached marine mammals and seabirds in Santa Barbara and Ventura is due to domoic acid poisoning.
In April, the SBWCN began to receive calls regarding pelicans exhibiting signs of neurological disfunction associated with domoic acid poisoning such as confusion, lethargy, seizures, head-bobbing or weaving, and foaming at the mouth. In total, the SBWCN has received 93 pelicans since the beginning of the year.
Pseudo-nitzschia, the species of planktonic algae responsible for the production of domoic acid, periodically bloom in the waters off California’s coastline. It is thought to be a naturally occurring phenomenon, but can be intensified by human influences such as nutrient runoff from farms and other sources. Scientists also speculate that global climate change could impact Pseudo-nitzschia levels. Pseudo-nitzschia thrive in warmer water that has received high levels of nutrients from cold, deep, nutrient-rich water moving to the surface in an event known as upwelling. However, Pseudo-nitzschia are thought only to produce toxins when exposed to a stressful environment such as excess carbon dioxide in the water.
Marine species high up the food chain, such as sea lions, dolphins, and fish-eating (piscivorous) birds, are especially susceptible to domoic acid poisoning since the toxin accumulates upon ascent within the food chain. Domoic acid builds up in shellfish, and consequently, the California Department of Public Health warned people not to eat shellfish harvested noncommercially from California waters. Unfortunately, domoic acid poisoning can be fatal, and of the 344 birds that the SBWCN has treated since January, only 126 pelicans and pelagic birds survived long enough to be stabilized and consequently released or transferred to the International Bird Rescue in San Pedro for extended care.
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