Your Happiness Kills Crustaceans

Figure 2 from paper: Mean average phototaxis and geotaxis score of E. marinus exposed to varied concentrations of serotonin (n = 20 per treatment) over a 3-week period. Error bars to one standard deviation. *Significance compared with control determined by Mann–Whitney and Bonferroni correction p < 0.0125.

Nearly 30-90% of the pharmaceuticals we digest are excreted in its active form. These active pharmaceuticals collect sewage systems and eventually make their way to streams, rivers, lakes, and oceans. What are the effects of these pharmaceuticals on aquatic and marine organisms?

In a recent study, scientists exposed crustaceans, the amphipod Echinogammarus marinus, common in the freshwaters of Portugal to multiple drugs. Amphipods demonstrated increased response to light (phototaxis) and gravity (geotaxis) when exposed to serotonin.

Fig. 1 from paper. Mean average phototaxis and geotaxis score of E. marinus with acanthocephalan infection and a non-infected control group (n = 20 per treatment). Error bars to one standard deviation.*Significance compared with control(p < 0.05).

The Acanthocephala parasite Rhadinorhynchus. I don't care if that big predator is heading my way...I'm just soo damn happy. Image from Wikimedia Commons

Echinogammarus says "I am going to the big light"

As background, serotonin is the neurotransomiter that produces that happy feeling and serves to regulate our moods by aiding with sleep and reducing anxiety and depression. Interestingly, certain parasites are known to increasing swimming behavior in amphipods through increasing serotonin levels. Amphipods with parasite loads also exhibited increased photo- and geotaxis. All this “extra” swimming makes the amphipods stand out to predators, allowing the parasite to complete the next host phase, i.e. the predator, in its lifecycle.

The effects of Fluoxetine (Prozac, Sarafem) were also tested on amphipods. Fluoxetine works by increasing the amount of serotonin in the system.  As expected, Flouxetine significantly altered phototaxis and geotaxis activity with the greatest change occuring at concentrations of 100 nanograms per liter.

Fig. 3b from paper. Mean phototaxis score of E. marinus exposed to varied concentrations of fluoxetine over a3-week period. (b) Trial 2 phototaxis behavioural assay. Error bars to one standard deviation. *Significance compared with control determined byMann–Whitney and Bonferroni correction p < 0.0125.

Take home message: Our use of antidepressants kill off that little crustaceans and generally alter the ecological interactions of organisms in the water.

Guler, Y., & Ford, A. (2010). Anti-depressants make amphipods see the light Aquatic Toxicology DOI: 10.1016/j.aquatox.2010.05.019

Dr. M (1641 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, created to facilitate research to address fundamental questions in evolutionary science. He has conducted deep-sea research for 11 years and published over 40 papers in the area. He has participated in dozens of expeditions taking him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses mainly on marine systems and particularly the biology of body size, biodiversity, and energy flow. He focuses often on deep-sea systems as a natural test of the consequences of energy limitation on biological systems. He is the author and chief editor of Deep-Sea News, a popular deep-sea themed blog, rated the number one ocean blog on the web and winner of numerous awards. Craig’s popular writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.





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2 comments on “Your Happiness Kills Crustaceans
  1. Why did you post the charts for reaction to serotonin instead of data for the pharmaceuticals mentioned? It is relevant for comparison, yes, but serotonin is not what is getting flushed down our drains and into their habitats. Of the three anti-depressant drugs tested, one (fluoxetine aka Prozac) had a rather significant effect but the other two did not. It’s very good to see research like this being done as it does seem likely that pharmaceuticals in the environment could muck things up badly, but without more specific examples like this it will be hard to change what people do.

  2. Well, if my biology class serves me correctly, pretty soon we’ll be able to get stoned from eating lobster!

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