Studies will focus on ocean acidification’s effect on stone crabs and the complex relationships within ocean ecosystems
Mote Marine Laboratory is pleased to announce two new Mote Postdoctoral Research Fellows, whose research is now ramping up, following a selection process that concluded in late 2016. These next-generation researchers helped Mote attain a key 2016 goal in its 2020 Vision & Strategic Plan: to have at least five Mote Postdoctoral Research Fellows.
Dr. Philip Gravinese is located at Mote’s Sarasota campus and is working with Mote's Fisheries Ecology & Enhancement Program to research the effects of ocean acidification (OA), climate change and low oxygen levels on stone crabs.
OA refers to the chemical reactions that take place when carbon dioxide (CO2) from the atmosphere is absorbed by seawater. This water chemistry change ultimately lowers the ocean's pH (making it more acidic) and is often called the “osteoporosis of the sea.” Lower ocean pH is expected to weaken and even dissolve calcium carbonate structures in corals and marine animals with shells including stone crabs.
Juvenile crabs use calcium dissolved in the water to form their shells, but the more acidic the water the harder it may be for them to absorb the mineral. This could make them grow slower, generate softer shells and may leave them more vulnerable to predators.
“Florida’s coastal watersheds have suffered from decades of urbanization, which has redirected nutrient rich runoff into coastal areas. This nutrient rich runoff is resulting in lower oxygen levels and is simultaneously accelerating the rate of OA within some of Florida’s coastal systems,” Gravinese said. “Coupled with the global-scale stress of elevated seawater temperatures, the alteration of Florida’s coastal habitats could have damaging ramifications for the stone crab fishery.”
The commercial fishery for the Florida stone crab contributes over $25 million a year to Florida’s economy; however, since 2000, the mean annual commercial catch has declined by approximately 25 percent.
“The deteriorating condition of Florida’s coastal habitats is concerning as they play a critical role in the stone crab life cycle. The embryonic development, larval release and larval development of stone crabs occur within coastal regions and are sensitive to OA. Some of Florida’s coastal habitats are experiencing declines in pH that are estimated to be three-times faster than that of the open ocean,” Gravinese said.
Gravinese’s potential future projects include determining the impacts of Florida red tide on stone crabs and assessing how increased freshwater flow into parts of Florida Bay may impact post larvae and juvenile stone crab survival, growth and physiology.
“A more comprehensive understanding of how stone crab larvae, post-larvae and juveniles respond to multiple environmental stressors like OA, elevated temperature and red tide will provide additional tools for managers to use in their interpretation of crustacean fishery data,” said Gravinese.
Four years ago, Gravinese co-founded an international marine-science filmmaking competition for K–12 students called Youth Making Ripples. The Youth Making Ripples competition serves as a platform for elementary, middle and high school students to promote ocean conservation messages within their communities.
“Throughout my Ph.D. I have attempted to bridge the communication gap between the scientific community and the general public by participating in a variety of educational outreach initiatives. Helping create the Youth Making Ripples program established an exciting and engaging outlet for the next generation of ocean enthusiasts to promote conservation messages that are important to them on a national level,” Gravinese said.
Gravinese earned his undergraduate and masters degrees in marine science from Florida Institute of Technology in 2003 and 2007. He then taught high school and local state college science classes for five years and earned his Ph.D. in biology from Florida Institute of Technology in December 2016.
Dr. Rob Nowicki, a marine ecologist based at Mote’s Summerland Key campus, studies the complex relationships among ocean animals, plants and their non-living environment.
Ecology reveals how one change to the ecosystem can lead to others. In a well-known example, the reintroduction of wolves in Yellowstone National Park deterred their prey, elk, from eating plants in some areas. This ultimately gave some species of trees and shrubs a better chance to reach adult size, changing parts of the landscape. By uncovering such relationships, scientists can form theories about how ecosystems work, but theories don’t hold up in every case. Understanding when and where ecological theory works as expected is challenging but necessary for managing and restoring ecosystems.
Nowicki tests the limits of ecological theory in the ocean, where many predator-prey relationships and other ecological patterns remain mysterious. Better understanding ocean ecosystems is critical for improving protection and restoration efforts.
At Mote’s Summerland Key campus, researchers are studying possible strategies to restore coral reefs, which are commonly nicknamed “rainforests of the sea” for their diverse, valuable ecosystem services.
“If we want to restore coral reefs, we can only take existing theory so far,” Nowicki said. “Eventually we need to take the training wheels off and put theories into action to see where they hold.”
For example, scientists suspect that patchy coral reefs of Florida and Caribbean have healthier fish communities if seagrass beds are nearby, since many juvenile fish start their lives among seagrasses and move to reefs later. However, many reefs have a “halo” of empty sand, where reef fishes have eaten the seagrasses and fled back to the reef to hide from predators. This halo could be a tough barrier to young fish, giving them nowhere to hide between seagrass nursery and reef.
Theoretically, if scientists fill that gap with artificial seagrass, young fish might be better able to hide, less likely to be eaten during crossing. Nowicki and colleagues will test this hypothesis with a one-year study starting in June 2017 in the lower Florida Keys Reef Tract between Summerland Key and Key West.
“We will build artificial seagrass beds to give reef fish a bridge across those dangerous haloes,” Nowicki said. “If that has the expected effect, it tells us that proximity to seagrass is important for this kind of reef. That could mean reefs with seagrass right next to them might be good places for coral restoration. Also, it could mean that more seagrass beds could help jump-start fish recruitment. We care about having fish on the reef because people like to eat some reef fish species, and others control algae that can out-compete coral.”
Nowicki’s other goals include monitoring populations of large sharks in the Florida Keys and studying how native and invasive reef predators impact the reef environment.
Nowicki earned his doctorate from Florida International University (FIU), studying how major declines of seagrass in Shark Bay, Western Australia, affected the populations, behavior, and predator-prey relationships of a variety of species, including sea turtles, dugongs, and tiger sharks. He earned his bachelor’s degree in Marine Biology with a Chemistry minor, graduating Summa Cum Laude with honors from the University of North Carolina, Wilmington.
Beyond his FIU study of a seagrass ecosystem in Western Australia, Nowicki has participated in multiple shark research cruises with the organization OCEARCH, served as a research assistant at FIU, an ecological consultant with Pew Charitable Trusts, a research assistant at the University of North Carolina’s Institute of Marine Sciences, and more. He is a member of the Ecological Society of America and the American Elasmobranch Society, which focuses on sharks, rays and skates.