Abstract

When sea lions are exposed to high levels of domoic acid (DA), they can experience seizures, coma and death.¹ Effects of exposure to lower levels of DA remain unknown. Our laboratory studies animal models of autism. Detriments in social behavior are a core feature of the autism diagnosis^2,3 and we suspect that early exposure to DA may impair juvenile sea lion social behavior. Experimental studies with rodents, by our laboratory and those of others, suggest that social behavior is highly sensitive to prenatal DA exposure. DA can transfer across the placenta⁴ and through mother's milk⁵ and can influence brain development, including brain regions that regulate social behavior.^6,7 Adults express social withdrawal after infant exposures to DA at levels 100-fold below acute levels for adults.⁸ These long-term social deficits are more pronounced in males,⁸ resembling the sex bias for autistic social deficits. DA toxicosis and autism also share common phenotypes, including seizures^9-13 and increased brain excitatory tone.^13-17

Our laboratory has developed an ethogram to assess social behaviors of sea lions at The Marine Mammal Center. We installed Internet protocol cameras to observe and record sea lion activity in their pens from our remote location. We observe their behaviors throughout the day. Our ethogram considers the following kinds of social interactions on land and in the pools: bodily contact via nose, mouth, head/neck and flippers, orientation of the head toward a conspecific, social approach, proximity, social retreat, and reciprocal swimming (defined as one animal coordinating its swimming with a conspecific). Utilizing coding tools that are used for assessments of autistic children, we hypothesize that our ethogram will be highly sensitive to the location of possible DA-induced brain lesions in juvenile animals. Preliminary data is presented.

Acknowledgements

The authors wish to thank Dr. William Van Bonn and the volunteer staff at the Marine Mammal Center for their help with the animals. This project was supported by pilot funding from Oregon Sea Grant.

*Presenting author

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