Project: EMBRACE-OCE-Seed: Temperature and oxygen partial pressure effect on aerobic metabolism and carbon flux of vertically migrating salps

NSF abstract:
Salps, a type of gelatinous zooplankton, play a significant role in the ocean’s ecosystems, particularly in food webs and carbon cycling. Found throughout the world’s oceans, salps can rapidly bloom, consuming vast amounts of local primary production and contributing substantially to carbon sequestration by transporting carbon to deep ocean layers. This project seeks to understand how changes in temperature and oxygen levels affect the metabolic rates and carbon export capabilities of salps. Understanding these impacts is crucial for accurate ocean carbon cycling models and can help predict future changes in marine ecosystems. This project will advance the field of marine biology by filling significant gaps in our understanding of salp physiology and their role in carbon cycling. It will also support the training and education of underrepresented groups in marine science by integrating undergraduate students, particularly from underrepresented communities, in hands-on research, thereby fostering the next generation of scientists.

Salps (subphylum Urochordata, class Thaliacea) are an often-overlooked lineage of zooplankton that play a major role in carbon sequestration exporting as much as 46% of net primary production via respiration and fecal pellet production out of the euphotic zone. Understanding salp physiology is critically important for building accurate ocean carbon cycling models. Yet, there is very limited data available on salp physiology, and almost none on the effect of temperature and oxygen concentration on rate processes such as routine aerobic metabolic rate (RMR). The proposed research will characterize changes in RMR of both blastozooids and oozooids of the three most dominant species of vertically migrating salps in the Sargasso Sea. Oxygen consumption will be measured at temperatures consistent with the surface and at 200 m depth. Individuals will be held in respirometers and allowed to breathe down oxygen to lowest detectable levels to examine the effect of oxygen partial pressure on RMR. The resulting data will be incorporated into previously published carbon flux models for Sargasso Sea salps to determine what effect temperature and oxygen have on their carbon flux. As ocean temperatures continue to change both temperature and oxygen concentration will become important constraints on aerobic capacity and will affect activity, growth, and reproduction. As these changes occur, a greater understanding of salp metabolic physiology will improve our ability to more accurately predict salp contributions to carbon flux, an area of priority research in the biological pump community. This study will benefit society by providing unprecedented insight into how salps’ metabolism and carbon flux are affected by changes in temperature and oxygen content during their daily vertical migrations as well as the impact that climate change may have on salp physiology.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.