What s next for blue crabs? Forecasting blue crab range expansion into the Gulf of Maine Tanya Rogers Ph.D. Student Northeastern University Marine Science Center Nahant, MA
Kaneohe Bay, Hawaii
San Francisco Bay, CA
Kaneohe Bay, Hawaii
Kaneohe Bay, Hawaii
Kaneohe Bay, Hawaii
Bodega Bay, CA Bodega Marine Lab
San Juan Islands, WA Friday Harbor Labs
Great Barrier Reef, Australia Lizard Island Research Station
Smithsonian Tropical Research Institute Panama
Florida State University Coastal & Marine Lab Florida
New England Northeastern University Marine Science Center
Species Ranges
Climate Change and Range Expansion North North South South
Climate Change and Range Expansion North North South South
Blue Crabs (Callinectes sapidus) Cape Cod Beautiful savory swimmer Live in coastal estuaries Omnivorous diet (predators and scavengers) Lifespan: 3-4 years Adult size: 4-9 inches Chesapeake Bay Blue Crab Range
Blue Crab Range Expansion? Gulf of Maine 2012-2014 sightings Cape Cod Historic blue crab range sightings from Johnson (2015)
Estuaries Provide Important Sevices protect shorelines from storms, floods, erosion filter water (remove pollutants and sediment) remove and recycle nutrients sequester carbon provide habitat for valuable species Threatened by: Coastal development Pollutants and nutrients in run-off Invasive species Sea level rise & Climate change
Blue Crabs are Important Predators +
Blue Crabs are a Major Fishery 8 th largest commercial fishery in U.S. 5 th largest in value (over $200 million dollar industry) Over 60,000 metric tons caught annually 75% from North Carolina, Virginia, Maryland, Louisiana Important recreational fishery in New England Source: NMFS 2010
Blue Crabs aren t alone Green Crab Range Chesapeake Bay Blue Crab Range Cape Cod Invasive species from Europe Similar diet as blue crabs Similar habitat use Cause a lot of problems salt marshes seagrass beds softshell clam beds Large blue crabs can eat green crabs
Research Questions What limits the northern range of the blue crab? Will blue crabs expand their range northward as climate warms? How will salt marshes be affected by blue crabs and directly by temperature increases? How do blue crabs interact with invasive green crabs?
Blue Crab Life Cycle inner estuary outer estuary open ocean juveniles and adults growth (summer) megalops (late larval stage) mating migration settlement spawning (spring) zoea (early larval stage) hibernation (winter) mated females
What limits the northern range? Physiology (too cold)
What limits the northern range? Physiology (too cold) Maine Coastal Currents Georges Bank Nova Scotia Current Recruitment limitation (crabs can t get there) Species interactions (predator or competitor) Gulf Stream Lack of habitat or food
What limits the northern range? Physiology (too cold) Maine Coastal Currents Georges Bank Nova Scotia Current Recruitment limitation (crabs can t get there) Species interactions (predator or competitor) Gulf Stream Lack of habitat or food
Blue Crab Life Cycle inner estuary outer estuary open ocean juveniles and adults growth (summer) 15-20 C megalops (late larval stage) mating migration settlement spawning (spring) zoea (early larval stage) 20-25 C hibernation (winter) 0-3 C mated females
Temperature ( C) Adults and Late Larval Stages Wells Bay, ME 0-3 C 15-20 C Waquoit Bay, MA Within-estuary water temperature Waquoit Bay, MA Wells Bay, ME
Temperature ( C) Early Larval Stages 20-25 C Nantucket Sound Cape Cod Bay Nantucket Sound Sea surface temperature Early larval stages likely limited by cold temperatures in the summer Cape Cod Bay
Blue Crab Density (June) Blue Crabs and Temperature Crab Density Data from Mass DMF Flounder Surveys (1976-2014) Blue crab densities generally increase with increasing temperature Waquoit Bay, MA 2002-2014 2012 Southern Cape Cod 1987-2014 2012 Within-Estuary Temperature ( C) (May Average) Sea Surface Temperature ( C) (May Average)
How will marshes be affected? 1) Where are the crabs and what do the marshes look like? Surveys to describe patterns in crabs, invertebrates, and plants north and south of Cape Cod (2014-2015) 2) How will crab introduction and temperature increase (alone and together) affect marshes? Lab and/or field experiment based on surveys, using existing environmental gradient (2016-2017)
2014 Summer Survey Sites
inner Within-Estuary Surveying mid outer
Crab Trapping 5 meters back from creek bank creek channel creek bank Crab species Crab abundance Crab size Crab sex
Vegetation & Invertebrate Surveying Vegetation cover Vegetation height Invertebrate abundances crab burrows mussels snails other crustaceans
Crabs per Trap Crabs per Trap North Green Crabs South North Blue Crabs South Creek
Crab Burrows (# per Quadrat) Mussels on Creek Edge (# per Quadrat) North Mussels South North Crab Burrows South Creek
2015 Summer Survey Sites
inner creek 2015 Sampling main channel outer creek 9 traps trap placement 12 hours inlet 200 m
Blue Crabs Green Crab Interactions only at higher temperature green crabs big blue crabs small blue crabs does growth rate depend on temperature? shared prey Intraguild Predation does competitiveness depend on temperature? Asymmetric Size-dependent Temperature-dependent
Blue Crabs Green Crab Interactions Green Crab Range Cape Cod Chesapeake Bay Can temperature dependent interactions explain where crabs coexist and don t coexist? Blue Crab Range
Blue Crabs Green Crab Interactions
Blue Crabs Green Crab Interactions ha ha! Who gets the food?
Blue Crabs Green Crab Interactions nom nom nom! Who gets the food? Did a predation event occur?
Blue Crabs Green Crab Interactions 10 C 20 C 30 C Who gets the food? Did a predation event occur?
Blue Crabs Green Crab Interactions Green Crab Range Cape Cod Chesapeake Bay Can temperature dependent interactions explain where crabs coexist and don t coexist? Blue Crab Range
Why Crab Zonation? Negative interactions between species, or different environmental preferences? Does this partitioning of habitat allow for their coexistence? Will have undergrad working on this summer
Implications Environmental and biotic (predatory) controls of disruptive, invasive green crabs - Possible biotic control by native predator? Whether blue crabs are coming to an estuary near (or just north of) you How crabs and climate change impact marsh ecosystem services
How you can help me: Let me know if you see (or have ever seen) any blue crabs north of Cape Cod Alive, dead, or shells (molts)? When and where? How big? rogers.ta@husky.neu.edu
Acknowledgments Advisor: Dr. David Kimbro Committee members: Dr. Brian Helmuth Dr. Jonathan Grabowski Dr. Tarik Gouhier Dr. Amy Freestone Partners: Waquoit Bay NERR Narragansett Bay NERR Great Bay NERR Wells Bay NERR Steward B. McKinney NWR Parker River NWR New Partners (2015): Orleans Conservation Trust Conservation Commissions of Duxbury, Sandwich, Brewster, Harwich, and Chatham Cape Cod National Seashore Field Help: Joe Gladstone & Forest Schenck Funding: Northeastern University MSC NSF Graduate Research Fellowship Data: Massachusetts Division of Marine Fisheries U. Maine Satellite Oceanography Data Lab National Estuarine Research Reserve System Crab Drawings: Myself Contact info: Email: rogers.ta@husky.neu.edu Lab website: kimbrolab.weebly.com