Interactive roles of temperature and food availability in predicting habitat suitability for marine invertebrates

Abstract

Natural variability in habitat characteristics, including their interactions, can affect marine invertebrate development. Controlled laboratory experiments seek to assess responses to such variability. For marine invertebrates, responses to temperature are typically assessed but a continuous gradient of all temperatures that a species may encounter is not frequently used. For planktonic larvae of marine invertebrates, biotic factors such as food availability receive less attention due to difficulty in simulating planktonic biotic interactions in a controlled laboratory setting. Here, a laboratory experiment was used to quantify larval development (growth, pelagic larval duration and survival) of the Atlantic surfclam, Spisula solidissima, in response to a continuous range of temperatures and food (phytoplankton) concentrations, allowing quantification of thermal and food availability niches. A second experiment was conducted to quantify the thermal and food availability niches for recruit (post-settlement) surfclams. These experiments were uniquely designed to inform future climate change-based forecasting and habitat suitability modeling. Larval growth and survival increased with increased food availability, while pelagic larval duration decreased with increased food availability. Larval survival decreased with increased temperature, growth peaked near 22 °C and pelagic larval duration was lowest near 22 °C. For recruits, survival and growth increased with both temperature and food availability, but growth decreased at temperatures >22 °C. Broadly, results suggest potential food limitation for continental shelf bivalve larvae and demonstrate that natural variation in food availability may affect thermal tolerances. Results also suggest that throughout the range of the surfclam, high food and moderate temperature areas such as New York Bight and Georges Bank are ideal for larvae and early recruits, whereas low food and high temperature areas, including continental shelf waters in the southern Middle Atlantic Bight, are suboptimal for early life stages of surfclams. This framework may be used for habitat suitability modeling, from an energetic perspective, for other marine invertebrate taxa.