A by nature - occurring algal toxin called domoic acid ( DA ) get brain lesions in ocean lions that can conduct to a range of needlelike symptom including disorientation and seizures . While this much was know , scientist in California have now discover the sphere of the nous that are affected by DA , disclose how persistent picture to the substance can top to lasting neurological equipment casualty .
DA is raise by a figure of algae belonging to thePseudo - nitzschiagenus , and therefore incline to become more saturated when these algae are in bloom . During these times , a number of maritime animals – include sure type of fish , birds and mammals – face an increased peril of suffering acute poisoning , although until recently , marine life scientist had been incertain of exactly how this come .
Between April 2009 and November 2011 , a team led by researchers from the University of California , Santa Cruz , hit the books fantastic ocean lions undergoing rehabilitation following DA exposure , in Holy Order to learn more about its effects on the genius .
To do so , they excogitate a number of exercising that would examine impairment to the ocean lions ’ spatial retentivity . For instance , the brute were repeatedly put through a tangle , enabling researchers to observe their ability to sail and memorize their environs . to boot , the sea lions were presented with buckets in four locations each day , one of which always contained food while the other three did not . By canvass their power to study which location contained the food , the team was able to further assess the animals ’ stratum of cognitive equipment casualty .
They then used operable magnetic plangency imaging ( fMRI ) to key out a correlation between brain structure and behavioral symptoms in the ocean lions . In particular , the researcher focus on the correct dorsal hippocampus , since previousstudiesin humans and rodents had indicated that this part of the learning ability is for the most part creditworthy for spatial memory .
Publishing their results in the journalScience , the squad note that ocean Lion displaying afflicted navigational capacity tend to suffer from right dorsal hippocampal lesions , result in a decrease in volume of this part of the learning ability . Additionally , they discovered a reduction in communicating between the hippocampus and a region called the thalamus in these subjects .
However , they also regain that this type of terms does not necessarily occur every metre that acute DA poisoning symptom are see , suggesting that lasting changes to the hippocampus only ensue from repeat picture to the toxin . In astatement , study tether author Peter Cook explain that this raises a number of further questions that must be addressed in next research . “ We do n’t know how weighed down the vulnerability demand to be , or how often repeated , to cause this sort of brain price , and we do n’t know the effects of repeated low - dose exposure , ” he said .
The implications of this enquiry are potentially important for global sea Leo populations . As the study explains , “ because ocean lions are dynamic foragers that swear on flexible navigation , impaired spatial memory may affect survival in the state of nature . ”
Such risk are particularly prevalent at present , since a number ofstudieshave betoken that DA - producingPseudo - nitzschiaalgal rosiness are currently increasing . Though this addition has been attributed to “ natural climate variability ” rather than man - ram change to ecosystems , it present a major challenge to conservationists working with ocean lions and other marine species that may be susceptible to district attorney poisoning .
