Algal Blooms Kill California Seabirds
This spring, the International Bird Rescue Research Center has seen a record number of seabird deaths on Southern California’s shores. Scientists at the center speculate that recent blooms of algae containing toxic domoic acid are more virulent than ever before, leading to abnormally high cases of DA poisoning in many species of sea life.
‘I have been doing this work for 35 years and I have never seen anything like this as far as the number of species affected, other than an oil spill,’ IBRRC director Jay Holcomb said.Ê
Seabirds with DA poisoning will literally fall from the sky due to brain seizures. Others crash into car windshields or fly dangerously onto airport runways. Many seabirds drown, making it difficult to record an exact number of DA-related deaths.
IBRRC researchers first started noticing the problem in March, reporting that there were ‘dead birds everywhere.’ Not all birds tested positive for DA poisoning, however; other neurotoxins such as saxitoxin, which can cause paralytic shellfish poisoning in humans, are also being examined.
The Marine Mammal Care Center has noticed similar trends in sick seals and sea lions, which share the seabirds’ diet of anchovies and sardines. Because these fish feed on DA-carrying algae but are not affected by the toxin, their predators – depending on how many fish they consume – will often ingest concentrated amounts of DA.
In humans, DA poisoning can cause many hazardous symptoms, including vomiting, loss of short-term memory, cardiac arrhythmia, coma, motor weakness and even death. Due to permanent short-term memory loss, the condition is often called amnesic shellfish poisoning.
‘In my opinion, domoic acid is the new DDT,’ Holcomb said. ‘If the effects of DA poisoning are cumulative in the brain, and we don’t know that yet, it could have serious consequences on the population of California brown pelicans.’
Lizards Prefer Islands, UCSD Survey Says
After surveying lizard populations on islands across the globe, UCSD scientists have confirmed that island species are more numerous than their mainland counterparts.
This suggests that a climate change would have severe consequences for lizards and other animals that inhabit islands, because island ecosystems are more sensitive to change than mainland ecosystems.
‘We found that island populations are less resistant to biological invasions, which will likely increase dramatically with changing climate,’ said assistant professor of biological sciences at UCSD and study co-author Walter Jetz.
Jetz, along with co-author Lauren Buckley, gathered extensive global findings on lizard population densities – the first study of island densities for any animal group.
They found that lizards were over 10 times more populous on islands than on the mainland. This is because in isolated areas, predation and competition is greatly reduced.
‘The ecology of islands is particularly important because, while the world’s more than 100,000 islands constitute only 7 percent of the global land surface, they contain many of the earth’s species with numerous species restricted to single islands,’ Buckley said.Ê ‘Five hundred million people depend on island ecosystems for their food and livelihoods.’
