Was the heat too hot for L. pictus to handle?

— Written by Carlos Estrada

After a temperate and not-so-long summer, the Lytechinus pictus project has come to an end. In that time, I’ve unfortunately caused the deaths of a few of my beloved urchin, but in the process raised hundreds of thousands of larvae. All in the name of science! And have I got science to report! We’ll start with what was surprisingly the most difficult part of project, taking pictures.


Some quick analysis of variance (ANOVA) showed that there was no significance between the lengths of the larvae and the temperatures in which they were reared at any stage. The gastrula stage held the strongest relationship between rearing temperature and length, but very little relationship was seen with the prism and pluteus stages. This conclusion corresponds with that of Hammond and Hoffman (2013), which found that increased temperatures had no significant effect on larval skeletal length. Developmental timelines, however, differed as predicted with larvae reared in the 20°C buckets reaching all three stages much quicker than those reared in 17°C buckets.

Thermal Tolerance

Preliminary data shows significance between rearing temperature and thermal tolerance at both gastrula and pluteus stages. The prism stage, however, shows no significant difference between the two rearing temperatures.  All life stages showed little to no mortality until they reached higher temperatures, in which mortality increased dramatically. Although the beginning in mortality can differ, 31°C seems to be the temperature at which mortality reaches 90-100%.

Heat Shock: hsp70 Expression

Unfortunately, my first attempt at attaining any data on the expression of the heat shock protein hsp70 through gel electrophoresis did not go well. No bands appeared on my gel, but don’t panic! After a few tweaks to our formula, we’re ready to make another stab at it first thing in the morning. My partner-in-crime, Erin DeLeon Sanchez, has run her own gel in the past with pluteus DNA that showed bands. She also went to the trouble of conducting qPCR and found that hsp70 expression was stable throughout all both rearing temperatures and heat shock temperatures.


Very little ecological research has been done on Lytechinus pictus and I can’t express how proud I am to have done my part. But more studies are needed to better understand the relationship between this urchin and it’s changing environment. Such studies could help us predict not only this species current and potential future biogeography, but that of its prey and predators as well.

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