Turning up the heat on the painted sea urchin

— Written by Carlos Estrada

With global ocean temperatures and acidification on the rise, it is becoming increasingly important to study in what ways marine life may be affected. Slow-moving echinoderms, such as sea urchins, may be especially vulnerable due to their inability to migrate far distances in a short time. Ocean acidification has been shown to stunt the skeletal growth of purple urchin larvae whereas elevated temperatures increases their developmental rate (Padilla-Gamino 2013). If these increases in acidity and temperature continue, urchin larvae size may decrease, leading to further predation and low survivability. These effects on urchins are not only threatening to this species, but to the entire ecological system in which they belong. Sea urchins are important in keeping kelp forests in check and also serve as food to a variety of organisms, including the California sheephead and otters. Any detriment to urchin development may prove disastrous to this delicate balance, which is why this summer I will be studying an urchin species not previously studied in the Hofmann lab known as Lytechinus pictus, commonly referred to as the painted sea urchin.


Lytechinus pictus. Picture taken in the Hofmann Lab’s seawater room

Unlike the purple urchin, which is found as far north as Vancouver and as far south as Baja California, L. pictus is found from central California all the way down to the Ecuador. This makes L. pictus particularly interesting to study due to its tropical habitat and wide-ranging temperatures that fall anywhere between 9°C and 23°C. My project will attempt to answer a few questions regarding the effects of increased rearing temperatures on L. pictus larval development. The focus of this project will be to find the thermal tolerance of L. pictus and whether thermal tolerance varies across developmental stages by observing four different stages. This will allow me to see if there are any developmental stages that are most vulnerable to increased water temperatures. Morphometrics will also be involved by taking pictures of these different stages to check for differences in size or abnormalities. Lastly, but certainly not leastly, my project will have me look at whether thermal tolerance reflects expression of the heat shock protein hsp70. What makes this project so exciting (other than learning about invertebrate development, as well as new molecular skills!) is that very few studies have been conducted on L. pictus, making it feel as though I’m traveling directly into uncharted waters. So, hopefully, by the end of this summer we will have a better understanding of how echinoderms in warmer climates might fare when faced with increasing ocean temperatures.

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