Lower pH Levels Negatively Affect Tripneustes gratilla Fertilization and Development

Overview

As human carbon dioxide emissions dissolve in the ocean, the pH of the ocean drops in the natural phenomenon known as ocean acidification (Brewer 2013). In 2100, the oceanʻs pH is predicted to be 7.6 (NOAA Ocean Acidification Steering Committee). Testing on urchin gametes is a possible method of concluding whether or not other sea urchins and other organisms can survive in a given water quality (Dinnel 1989). The sea urchin Tripneustes gratilla is often used as an indicator of water habitability due to its sensitivity to water quality. This study used T. gratilla eggs to measure fertilization rates in different pH levels. Eggs were fertilized in different pH levels, ranging from pH 8.3 (a healthy ocean pH) to pH 7.6 (the pH level predicted to be in 2100). Successfully fertilized eggs were counted after 40 minutes. The hypothesis that fertilization success would be low at a pH of 7.6 was reflected by the data. Lower pH levels were also harmful to sperm motility and stumped embryo development but had no effect on egg viability. Results suggest that lower pH levels significantly negatively impact T. gratilla fertilization and development rates. Therefore T. gratilla and many other species may be at risk in the future, due to projected lower pH levels.

Competition history

• JSHS 2023 Category not listed

Resources

• National JSHS abstract book ↗

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