Thermal Tolerance of Tigriopus californicus

— Written by Asher Albrecht

Tigriopus californicus

Global warming is one of, if not the most, significant issue causing changes in our oceans today, and along with other more publicized factors like increased ocean acidity and widespread increases in ocean temperature, unprecedented heat waves are another one of the new challenges that ocean life must face. These sudden and drastic surges in water temperature have been shown to have an even more detrimental effect on certain marine copepods than other effects of global warming. Other invertebrates are being affected as well; only a month ago scores of mussels along the coast have reportedly cooked in their shells while still attached to the rocks around California due to summer heat waves. Learning about the ability and extent to which marine fauna can adapt to these events is an important question when assessing potential changes and damage we may encounter as our planet’s temperature continues to increase. A plentiful, adaptive, and important marine species here along the California coast is Tigriopus californicus, a very small intertidal copepod that is used the variable environment present in tide pools along the coast. The relatively short spawning time of T. californicus, ease of feeding, size, significant role in the food web, and extreme adaptability all make it an ideal model organism to study this important phenomenon.

Water baths for accurate water temperature and circulation

The specifics of the project I am working on is still being finalized, and once we have some healthy populations up and running, a better sense of our resources, and I have read a couple more studies on similar topics, I will nail down the details of my research. For now, some specific areas of interest are the effects of increased temperature on female T. californicus fecundity, the tolerances of the various life stages of T. californicus, if increased temperature effects developmental timing and to what extent, and oxygen consumption. Just because I haven’t set my project in stone doesn’t mean I haven’t been busy in the lab! I have been working with another undergraduate named Michael who will be carrying out his own project involving T. californicus and heat tolerance, specifically the epigenetic mechanisms of temperature adaptation. Together we tested the heat tolerance of a sample of adult T. californicus from Point Dume in Malibu. First, we added between 4 and 6 random individual copepods to their own PCR tube. It’s difficult to truly appreciate the speed of such small animals until you have had to collect them by sucking them up individually with a micropipette. We filled 8 rows of tubes, with 10 tubes each. We exposed individual rows of copepods to a gradient of temperatures ranging from 36˚C to 38˚C and finished by counting the number of survivors in each tube underneath a dissecting scope. The eye strain was considerable, but it was exciting work none the less. We also recently constructed the baths that we can use to circulate water of a constant temperature around small holding tubs in order to test larger numbers of individuals. My plumbing skills have increased drastically, and Teflon tape is my new best friend. Tomorrow, we are leaving at 5 a.m. to go collect new samples from Point Dume!