When I last checked in, I had just begun a pilot study that would assess how shell thickness in mussels may be affected by exposure to Prozac. Unfortunately, the experiment was a bust, mostly owing to the impractical housing conditions which stressed the animals and led to high mortality. I quickly scrapped this project, with the intention of returning to it as a side project sometime later next year. My new focus will still assess the affects of prozac on marine life, but from a completely different angle: animal behavior.
I’d like to introduce this new project by telling you how I came up with the idea. While visiting Netarts, Nehalem, and Yaquina Bay, I noticed the abundance of shore crabs living in the estuary and that they reside primarily in soft sediments, mud, and beneath rocks, never too far from the water margin. This struck me as another creature that may be at risk from contaminants as they are transported from waters upstream and adsorb onto the sediments. I wondered if these crabs were in contaminated estuaries, how would their behavior change and how would this influence food web dynamics. To my knowledge, this is a somewhat unexplored connection linking contaminants as an agent to potentially influence shifts in food webs. We often hear about bioaccumulation of contaminants up the food web, but what if contaminants also affect the behavior of animals and cause them to be more or less susceptible to predation because of abnormal behavior?
The shore crab Hemigrapsus oregonensis, has been extensively studied and their behaviors have been well documented. My aim was to assess whether crabs exposed to Prozac at 3 and 30ng/L (i.e. documented concentrations in estuaries) would be more at risk of predation when compared to unexposed crabs. Because Prozac is a psychoactive drug, it is likely that their behavior will be altered at even low levels with persistent exposure. I am conducting this experiment by creating simulated estuary habitats in 30 tanks (10 replicates for each treatment) with rocky substrate and hideouts to allow for normal predator escape/evasion behavior. We will be dosing the shore crabs every 10 days with Prozac to simulate pulse events (e.g. increased rainfall) into the estuary. The meat of the study will be the addition of the predator, the Red rock crab, to the shore crab tanks and assessing the response to the predator during the behavioral trials, which will last ~1hr. We will run these behavioral trials during the day and at night to see observe their reactions. This project will run from June 1-August 15.
We have already had the animals living in our estuary mesocosms since June 1 and we will be conducting the first set of behavioral trials next week. More developments to follow. I’m very excited about this study and I believe it is important to explore how contaminants might affect wildlife in Oregon’s estuaries should we