what’s next for blue crabs? s next for blue crabs? forecasting blue crab range expansion into...

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

Panama

Smithsonian Tropical Research Institute

Florida Florida State University Coastal & Marine Lab

New England

Northeastern University Marine Science Center

Species Ranges

Climate Change and Range Expansion

North

South

North

South

Climate Change and Range Expansion

North

South

North

South

Blue Crab Range

Chesapeake Bay

Cape Cod

Blue Crabs (Callinectes sapidus)

“Beautiful savory swimmer” Live in coastal estuaries Omnivorous diet (predators and scavengers) Lifespan: 3-4 years Adult size: 4-9 inches

Blue Crab Range Expansion?

sightings from Johnson (2015)

Historic blue crab range

2012-2014 sightings

Cape Cod

Gulf of Maine

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

8th largest commercial fishery in U.S. 5th 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

Green Crab Range

Blue Crab Range

Chesapeake Bay

Cape Cod

Blue Crabs aren’t alone…

• 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

hibernation (winter)

spawning (spring)

inner estuary outer estuary open ocean

mating

zoea

megalops juveniles and adults

migration

mated females

growth (summer)

settlement

(early larval stage)

(late larval stage)

What limits the northern range? Physiology

(too cold)

Gulf Stream

Nova Scotia Current

Maine Coastal Currents

Georges Bank

What limits the northern range? Physiology

(too cold)

Recruitment limitation

(crabs can’t get there)

Species interactions

(predator or competitor)

Lack of habitat or food

Gulf Stream

Nova Scotia Current

Maine Coastal Currents

Georges Bank

What limits the northern range? Physiology

(too cold)

Recruitment limitation

(crabs can’t get there)

Species interactions

(predator or competitor)

Lack of habitat or food

Blue Crab Life Cycle

hibernation (winter)

spawning (spring)

inner estuary outer estuary open ocean

mating

zoea

megalops juveniles and adults

migration

mated females

growth (summer)

settlement

(early larval stage)

(late larval stage)

20-25 °C

15-20 °C

0-3 °C

Adults and Late Larval Stages

Wells Bay, ME

Waquoit Bay, MA

Tem

pe

ratu

re (

°C)

Waquoit Bay, MA Wells Bay, ME

Within-estuary water temperature

0-3 °C 15-20 °C

Early Larval Stages

Early larval stages likely limited by cold temperatures in the summer

Cape Cod Bay

Nantucket Sound

Sea surface temperature

Nantucket Sound Cape Cod Bay

Tem

pe

ratu

re (

°C)

20-25 °C

Blue Crabs and Temperature Crab Density Data from Mass DMF Flounder Surveys (1976-2014)

Sea Surface Temperature (°C) (May Average)

2012

Within-Estuary Temperature (°C) (May Average)

Waquoit Bay, MA 2002-2014

Southern Cape Cod 1987-2014

2012

Blu

e C

rab

De

nsi

ty (

Jun

e)

Blue crab densities generally increase with increasing temperature

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

Within-Estuary Surveying

mid

inner

outer

5 meters back from creek bank

Crab Trapping

creek bank creek channel

• Crab species • Crab abundance • Crab size • Crab sex

Vegetation & Invertebrate Surveying

• Vegetation cover • Vegetation height • Invertebrate abundances crab burrows mussels snails other crustaceans

Green Crabs

Blue Crabs

Cra

bs

pe

r Tr

ap

Cra

bs

pe

r Tr

ap

Creek

North South

North South

Mussels

Crab Burrows

Mu

sse

ls o

n C

ree

k Ed

ge

(# p

er

Qu

adra

t)

Cra

b B

urr

ow

s

(# p

er

Qu

adra

t)

Creek

North South

North South

2015 Summer Survey Sites

outer creek

inner creek

main channel

200 m inlet

9 traps

trap placement

2015 Sampling

12 hours

Blue Crabs – Green Crab Interactions

green crabs small blue crabs

big blue crabs

shared prey

Asymmetric Size-dependent Temperature-dependent

only at higher temperature does growth rate depend

on temperature?

does competitiveness depend on temperature?

Intraguild Predation

Green Crab Range

Blue Crab Range

Chesapeake Bay

Cape Cod

Blue Crabs – Green Crab Interactions

Can temperature – dependent interactions explain where crabs coexist and don’t coexist?

Blue Crabs – Green Crab Interactions

Blue Crabs – Green Crab Interactions

Who gets the food?

ha ha!

Blue Crabs – Green Crab Interactions

Who gets the food? Did a predation event occur?

nom nom nom!

Blue Crabs – Green Crab Interactions

10 C 20 C 30 C

Who gets the food? Did a predation event occur?

Green Crab Range

Blue Crab Range

Chesapeake Bay

Cape Cod

Blue Crabs – Green Crab Interactions

Can temperature – dependent interactions explain where crabs coexist and don’t coexist?

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