Primary producers, such as marine seaweeds, transform inorganic nutrients into organic matter through photosynthetic processes. Their cells chemically respond to their environment by producing biomass with different chemical compositions. Temperature is one environmental factor that can affect the chemical composition of primary producers (e.g., lipid, protein, and carbohydrate content) and alter its nutritional quality. Changes in nutritional quality of marine seaweeds due to ocean warming can have cascading consequences on herbivores at higher trophic levels.
In the present study, we examined the effect of ocean warming on the marine seaweed Palmaria mollis (dulse) commonly used in aquaculture, as our model primary producer and cultured juvenile red abalone, Haliotis rufescens, as our model primary consumer. Red abalone are important in food production and conservation aquaculture in California. The effect of temperature on the growth and chemical composition (lipid, protein, and carbohydrate content) of dulse and subsequent effects on the growth and chemical composition of red abalone were studied.
Juvenile red abalone were grown for 104 days, they were fed dulse grown under three different temperatures for at least three weeks. Abalone growth was measured at days 0, 40, 75 and 104 and their chemical composition (lipid, protein, and carbohydrate content) was analyzed at the end of the experiment. Dulse was grown by tumble culture at 13°C, 15°C and 17°C under artificial light for three weeks. Dulse mass was recorded every seven days and its chemical composition was analyzed every three weeks.
This study is a first step to understanding how possible changes in ecological interactions will affect the food chain. It will help to illustrate the effects of rising ocean temperature on primary producers and the subsequent effects on primary consumers. Furthermore, this study will also assist assessment of seaweeds nutritional value to the food web for biological and ecological investigations.