Climate Change

and the

Chesapeake

Bay Region

Chesapeake Bay region is likely to be sensitive to changes in long-term mean climate

Juxtaposed between: •subtropical & temperate climate zones•maritime & continental air mass source regions

ContinentalPolar

Maritime Tropical

Maritime Polar

Air mass types, source regions, & trajectories

Predicting future climate directions is an evolving science

•Difficult to quantify uncertainty•Models often disagree (e.g. Hadley & CCC precipitation)•Resolution in time & space is still far below requirements•Cannot resolve events on biologically relevant scales•We depend on best estimates, but need to keep improving models

High+2.7 to +5.3+1.0 to +1.5Temperature (C)Temperature (C)

Low-4 to +27-2 to +6RunoffRunoff (%)(%)

Medium+6 to +24-1 to +8Precipitation (%)Precipitation (%)

High+39 to +102+11 to + 31Sea level (cm)Sea level (cm)

Very high+50 to +120+20 to +30CO2 (%)CO2 (%)

ConfidenceConfidenceYear 2095Year 2095Year 2030Year 2030Variable (units)Variable (units)

From the Mid-Atlantic Regional Assessment (MARA 2000)

Chesapeake Bay watershed is an important ecosystem

Keystone system supporting the larger NE US coastal shelf •feeding ground & nursery area for many ecologically and economically important species-

Atlantic croakersummer flounderblueback herringAmerican shadspotstriped bass

bluefishAtlantic menhaden

• shallow water temperature• sea-level rise• precipitation• wind patterns and intensity• water circulation patterns

Climate change may affect

• affects metabolism, activity, feeding, growth, reproduction

• sensitivity varies with species, age, size, season

• sublethal effects may eliminate a species by favoring competitors, predators, parasites

Temperature is a ‘master factor’

Mya arenaria

Macoma balthica

Example: Distribution of oyster pathogen, Perkinsus marinus (Dermo)

Prior to 1980

From: Burreson & Calvo (1996)

1996

Warm Winters&

Drought

Flow & temperature changes may alter species’ distributions

Predicted temperature effects• poleward expansion of warm-water

species

• poleward retreat of cold-water species

• delayed replacement of “lost” species in estuaries

• disruption of community interactions

• habitat squeeze, e.g., striped bass

Soft clam (Virginia – Arctic)

Winter flounder (Virginia – Arctic)

3-spine stickleback (Chesapeake Bay – Labrador)

Cunner (Virginia – Labrador)

Lumpfish (Chesapeake Bay north)

Retreating Northward

Pink, white, brown shrimp (GOM - Virginia)

Black drum (uncommon N. of Delaware Bay)

Spotted seatrout (rare N. of Delaware Bay)

Atlantic stingray (Mex. – Ches. Bay)

Southern flounder (TX – Ches. Bay)

Blue crab relatives

Advancing Northward

Temperature and Oxygen

• Higher temperature increases metabolism and thus D.O. requirements

• Warm water holds less D.O.

• Warm water increases B.O.D., so D.O. levels drop further

Striped bass

Optimum conditions

Striped bass Stress conditions

Sea level rise caused by thermal expansion of water and melting of land iceSea level rise caused by thermal expansion of water and melting of land ice

Melting

Mid-range estimates (inches) of effective sea level rise by 2100 and by 2200 (changes in land elevation

factored in)

Portland19 43

New York22 48

Seattle19 42

San Francisco15 36

Los Angeles13 32

Charleston25 53

Grand Isle55 112

Miami Beach20 44

Source: U.S. EPA (1995).

Sea level rise will affect coastal erosion

purple

• loss of marshes• “armored” shorelines;

economic disruption• salt-water intrusion

pest/predator invasionshabitat squeezesalinization of freshwater

Sea level rise may lead to

Titus and Richman, 2000. Climate Research

Modeled 1.3 and Modeled 1.3 and 3.3 m elevations3.3 m elevations

Relative sea level rise in Chesapeake Bay(Solomons MD)

Sea level rise

Many tidal wetlands are deteriorating as a result of relative sea level riseHuman intervention is likely to interfere with landward retreat of wetlands

Blackwater National Wildlife Refuge (MD)

1938

1980N

MarshOpen WaterUpland

1 0 1 2 3

Kilometers

Due to nutria feeding as well as land subsidence and sea-level rise

Redrawn from: Kneib, 1997

Sea level rise and the implications for fisheries•loss of nursery area habitat & production

Precipitation may include intense rainfall events

Increased flooding, but probably much drier between storms. Will affect Increased flooding, but probably much drier between storms. Will affect river flow and thus estuarine circulationriver flow and thus estuarine circulation

Runoff after Runoff after

HurricaneHurricane

FloydFloyd

• increased runoff into estuaries will increase water column

stratification and hypoxia or anoxia

• this runoff will “squeeze” habitat if seawater also encroaches

• droughts will also affect estuarine habitat

Precipitation changes

Wet winter-springEnhanced spring bloom

Dry winter-springSubdued spring bloom

Spring flow affects:•Spring bloom•Primary production•Dissolved oxygen

• may affect upwelling, downwelling, circulation

• may influence coastal transport of blue crabs, menhaden, spot, bluefish, croaker...

Changes in wind patterns or intensity

1 - Southward transport

Blue crab larval transport

2 - Offshore mixing; upwelling (winds);

northward transport

3 - Onshore transport;

downwelling; late summer

winds

Coastal regions may be exposed to higher storm surges, especially if hurricanes become

more intense and more frequent

purple

Potential ecological responses to climate change

• GreenGreen: Life cycle of a generic marine species.

• YellowYellow: Abiotic changes in environment that directly affect dispersal, recruitment, and individual performance at various stages in life cycle.

• BlueBlue: Additional effects at the community level with changes in population size and per capita effects of interacting species.

• Proximate ecological effects of climate change thus include shifts in the performance of individuals, population dynamics, and community structure.

• Together these proximate effects lead to emergent patterns such as changes in species distributions, biodiversity, productivity, and micro-evolutionary processes.

Modified from Harley et al. 2006

2009 TREE 24:686-693 Walther et al.

Climate change and introduced species

Dermo disease

• Need to understand future concentrations and the biogeochemical cycling of greenhouse gases and aerosols

• Must improve representation of climate feedback processes in models– clouds, convection and precipitation, sea ice,

vegetation, oceans• Need better predictions of regional patterns

of change • There may be non-linear responses (“surprises”)

There are still many uncertainties