Award: OCE-1259255

Do you think mammals like bears are the only organisms on earth that hibernate during the “food-poor” seasons? If you said yes, you would be wrong. For almost 40 years, I have been studying a small crustacean (related to shrimps), the size of a rice grain, that lives in the Arabian Sea off Oman and Somalia and other coastal ocean areas around Africa and as far north as Spain.  This little creature lives at the surface of the ocean during the favorable (abundant food) season, which is when winds force deep water to the surface (called upwelling), and “hibernates” (lives in a diapause state) as deep as 2000 meters during the unfavorable seasons. What is the timing of the rise of this organism to the surface and its departure from the surface? What are the environmental cues that trigger these behaviors? This project has demonstrated that the organism, a copepod known as Calanoides natalis, reaches the surface of the ocean off the Sultanate of Oman in mid-to-late June, just before strong upwelling, and its associated blooms of phytoplankton (mostly single-celled plants that are food for C. natalis), begins in July. And C. natalis departs the surface once the sea surface temperature rises to roughly 27^oC and remains at that temperature, which is when the upwelling-favorable winds have died-off. Since wind speed and direction off Oman are partly governed by the snow and ice on the Tibetan Plateau, the physical variables that force upwelling have a climate component. This project has also demonstrated that climate change is occurring in the Arabian Sea region, and the little crustacean,Calanoides natalis, responds to changes occurring in the ocean by extending its time at the surface when temperatures are between 17^oC and 27^oC. Furthermore, prior to 2015, C. natalis reproduced once per upwelling season, while in 2016 during its extended stay at the surface, the species reproduced three times. Thus, the life cycle of C. natalis is changing as its physical environment changes.

Last Modified: 07/23/2018
Modified by: Sharon L Smith