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  • Writer's pictureHeidi Waite

Does the apple fall far from the tree?: Parental effects could save the California mussel

Updated: Nov 5, 2020

[A little bit about my research!]

Graphics by Heidi Waite

Increased temperatures due to climate change are causing mussel populations in Southern California to decline. Mussels may have a way to give their offspring an edge and survive despite temperature increases. My research focuses on how mussel offspring are affected by temperature and how parental environments might help their offspring cope with climate change.

The rocky intertidal is an extremely important coastal ecosystem where the ocean meets land; yet it’s a harsh place to live. It is covered by water during high tide and exposed to the elements (i.e. the sun, extreme temperatures) during low tide. Consequently, most animals including mussels are at their physiological limits. Mussels live close to or at their max temperature limits. As temperature increases and heat waves become more frequent, mussels will likely cross this maximum. The loss of mussels is harmful because they are “foundation species” which means they provide habitat for other animals. Mussels attach to the bare rock and create areas for other animals to live in (i.e. shaded holes) or on (i.e. barnacles) that otherwise wouldn’t exist. The disappearance of mussels would mean the loss of over 750 species that rely on mussels for shelter and food. For this reason, we need to understand how temperature will affect all life stages of mussels.

Orange County, CA ; Photo Credit: Heidi Waite
Crystal Cove State Park, Reef Point

Currently, studies mainly focus on adult mussels; however, little is known about their offspring called larvae. Mussels have life cycles similar to caterpillars. They start as larvae in offshore waters, then return to shore and metamorphosize into the adults. These microscopic larvae are considered the most vulnerable life stage to temperature, but scientists know little about how larvae deal with temperature. Sometimes the environment parents are exposed to can influence how well their offspring will do in the same environment. This is called parental effects and might be a way mussels can cope with climate change. If a larva’s parents lived in a hot environment, parents might pass on abilities to deal with higher temperatures. Yet, we don’t know if this occurs in mussels.

Graphic by Heidi Waite
Simplified life cycle of the California mussel

My research will investigate how the tiny larvae of the native California mussel (Mytilus californianus) are affected by temperature and how parental effects might help them cope with climate change. To do this, I will collect adult mussels from Crystal Cove State Park in Newport Beach, CA and expose them to high and low temperatures. Then, I will spawn them (i.e. stimulate release of eggs and sperm) and test the larva’s tolerance to temperature. I will measure the adult and larval tolerances by calculating their LT50 (the lethal temperature at which 50% of mussels die), which is a metric of thermal tolerance. I will also record growth, survival, and development of their larvae at high and low temperatures. This will help us understand how the larvae build their temperature tolerance and the ways they might use to help them persist under climate change. Ultimately, this research will help us understand the decline in mussels and how they will cope with climate change.

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