Wednesday 11 January 2017

Warming Oceans Could Be Increasing The Amount Of Deadly Toxins In Your Favourite Shellfish Dinners


If you were planning on having crab for dinner tonight, you might want to rethink your menu.

A new study has shown that warming ocean conditions are leading to an increase in numbers of toxic shellfish.

If consumed, the toxic shellfish can have serious health effects in humans, including seizures, memory loss and stomach problems.

An international team of researchers, led by Oregon State University, found strong correlations between toxic levels of domoic acid in shellfish and warm-water ocean conditions.

They suggest that these warmer conditions are orchestrated by two powerful forces – El Niño events and the Pacific Decadal Oscillation.

Looking at data from the last 20 years, the researchers not only show a clear link between domoic acid and these larger climatic phenomena, but also created a new model to predict future domoic acid risks in the Pacific Northwest.

Angelicque White, who led the study, said: 'In the natural world there are always variations, and it's been difficult to connect a specific event to larger forces that operate over periods of years and decades.

'To do so, long observational time-series are crucial.'

The model is based on the status of the Oceanic Nino Index and the Pacific Decadal Oscialltion – two measures of climate, ocean water movement, currents and temperature.

The researchers hope that their model could help coastal resource managers more effectively monitor this issue and protect public health.

If climate change continues to warm the oceans, domoic acid outbreaks could become a common event.

Domoic acid is a neurotoxin produced by phytoplankton, and enters the marine food web when toxic blooms of these micro-algae are ingested by animals such as anchovies and shellfish.

If it is ingested by humans, it can caused a range of issues, including stomach problems, seizures and memory loss.

Domoic acid events have also been linked to mass deaths of marine mammals, like sea lions, sea otters, dolphins and whales.

Matt Hunter, co-author of the study, said: 'Advance warning of when domoic acid levels are likely to exceed our public health thresholds in shellfish is extremely helpful.

'Agencies can use this model to anticipate domoic acid risks and prepare for periods of more intensive monitoring and testing, helping to better inform our decisions and ensure the safety of harvested crab and shellfish.'

Beyond problems with domoic acid levels, these warm climate phases can also have a direct detrimental effect on animals.

The warm phases lead to increased numbers of green crabs in waters, where they compete with native Dungeness crabs.

And the conditions also deliver communities of 'copepods' - types of small crustaceans that float with currents - from the south, that are associated with reduced salmon runs.

In the long-term, the researchers say that these osciallations to warmer conditions can reduce the strength of the south-flowing California Current, moving both warmer waters and higher levels of toxic plankton north.

Morgaine MicKibben, lead author of the study, said: 'Part of the concern is that a large influx of the plankton that produce domoic acid can have long-term impacts.

'For example, razor clams are filter-feeders that bioaccumulate this toxin in their muscles, so they take much longer to flush it out than other shellfish.

'The higher the toxin levels, the longer it takes for razor clams to be safe to eat again, perhaps up to a year after warm ocean conditions have subsided.'



Etiam at libero iaculis, mollis justo non, blandit augue. Vestibulum sit amet sodales est, a lacinia ex. Suspendisse vel enim sagittis, volutpat sem eget, condimentum sem.