November 18, 2015

El Nino Update: Algae Blooms Threaten to Disrupt Oceanic Food Chain

El Nino
A Dungeness Crab off the coast of California. Photo: Brian Feulner

While most of the time news about El Nino conjures up thoughts of unusually high water temps, intense weather, or even an increased number in shark attacks, there’s many other aspects of the phenomenon that can wreak havoc on sea life too. With the current El Nino being predicted to be stronger than the record breaking ’97/’98 El Nino, scientists have started to make predictions of how the event will affect our seas, and have recently given warnings to fisheries.

As far back as May, a joint team of scientists from NOAA and UC Santa Cruz began to track the largest recorded algal bloom ever seen in the Eastern Pacific, maybe anywhere. These blooms are common during El Nino years, but this years extra-strength El Nino is adding fuel to the fire. The bloom was further north than researchers have ever noted before as well. It’s hardly noticeable at sea level, where a cloudy greenish-brown hue can be seen in the water. But satellites picked it up early and the bloom continued to be monitored as it went as far south as Santa Barbara by September.

The single-celled algae is a phytoplankton called Pseudo-nitzschia. This type of Algae produces domoic acid, a powerful nuerotoxin that gets consumed by small fish and shellfish. When these small critters are consumed by sea mammals and birds the toxin causes the animals to become disoriented and lethargic, and can eventually lead to seizures and death. In humans, the domoic acid can cause Amnesic shellfish poisoning (ASP) if eaten in high enough amounts. ASP causes permanent short-term memory loss, brain damage, and even death. It was first diagnosed by doctors in 1987 when 3 people died and many became ill in Eastern Canada after eating Prince Edward Island Mussels that were full of domoic acid. Luckily, he amount of the toxin in the water itself isn’t at a high enough level to be harmful to swimmers or surfers.

El Nino
The single celled phytoplankton Pseudo-nitzschia. Photo: Larry Jon Friesen

By late October, levels of domic acid were high enough to promote officials to shut down an anchovy fishery in California, and to shut down razor clam digging and crab, as well as other anchovy fisheries in Oregon and Washington. Then in early November, the California State Fish and Game Commission voted to delay the start of the Dungeness Crab season indefinitely. This delay came just two days after a California Department of Public Health advisory issued a warning for people not to consume crabs caught in waters between the Oregon border and the southern Santa Barbara County line due to toxic levels of domic acid.

El Nino
Crab pots wait for deployment in San Francisco. Photo: Santiago Mejia
El Nino
A fisheries worker moves a large load of Dungeness Crab last season at Pier 45, San Francisco. Photo: Alvin Jornada

It’s a huge hit for fisherman as the crab is one of the West Coast’s most valuable fisheries, bringing in an annual $60 million in California alone. The ban is particularly untimely because Dungeness Crab is a popular ingredient in many Thanksgiving and Christmas meals. The commission added that the ban will be in place until amounts of the toxin found in shellfish decrease to a safe level, with no specific time given. In the meantime, fisherman that rely on crab for a majority of their income are left stranded at the dock. Usually, the levels of toxins in crabs decline in the winter, so hopes remain high that a portion of the season will be salvaged.

It’s important to note that these algal blooms are cyclical, and are not permanent. Past El Nino events in the nineties that had severe algal blooms that led to domoic acid issues were followed by strong La Nina events. La Nina is a cold water phenomenon similar to El Nino and often accompanied by upwelling that causes the water to become nutrient rich. These La Ninas saw a huge resurgence in good phytoplankton, a staple for a variety of life from the smallest zooplankton to the largest whale.

Stay tuned for more El Nino Updates as the season progresses!



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