Behavioral changes in fishes and crabs in contaminated estuaries Predator/prey alterations could have consequences for birds Judith S. Weis Rutgers University.

Behavioral changes in fishes and crabs in contaminated estuaries

Predator/prey alterations could have consequences for birds

Judith S. WeisRutgers University

Collection Sites

Piles Creek (PC)Polluted Site - Linden, NJ

Great Bay-Mullica River Estuary (TK)Cleaner Reference Site- Tuckerton, NJ

Sites

Piles Creek (PC)Polluted Site - Linden, NJSurrounded by industrial sites, a sewage treatment plant, and a major highway. Elevated levels of organic contaminants and metals have been found in sediments and biota.

Collection Sites

Great Bay-Mullica River Estuary (TK)Cleaner Reference Site- Tuckerton, NJ part of the Jacques Cousteau National Estuarine Research Reserve, part of 3,500 acres of protected salt marsh.  

BACKGROUND• MUMMICHOGS (KILLIFISH, FUNDULUS HETEROCLITUS)

FROM CONTAMINATED PILES CREEK ARE RESISTANT TO METHYLMERCURY, BUT RESISTANCE IS RESTRICTED TO GAMETES AND EMBRYONIC STAGES

• AS ADULTS, THEY DO NOT GROW AS WELL OR LIVE AS LONG AS FISH FROM CLEANER ENVIRONMENT

• ALTERED FEEDING BEHAVIOR MAY PLAY A ROLE – COMPARE FEEDING WITH THAT OF TUCKERTON (CLEAN) FISH

FEEDING EFFICIENCY OF PC AND TK FISH PC TK

STRIKES/PURSUIT 1.93 + 0.62 1.85 + 0.10

STRIKES/KILL 10.38 + 10.06 6.71 + 8.66

STRIKES/FISH/MIN 0.55 + 0.52 0.97 + 0.51* * P < 0.05

X + SD X + SD

NUMBER OF F. HETEROCLITUS EATEN BY BLUE CRABS OVER 14 DAYS

ORIGIN OF FISH # EATEN #NOT EATEN TOTAL

PC 23 7 30

TK 12 19 30

PREDATOR AVOIDANCE

• COMPARE SURVIVAL OF PC AND TK FISH WITH BLUE CRAB (CALLINECTES SAPIDUS) PREDATORS

NUMBER OF F. HETEROCLITUS EATEN BY BLUE CRABS OVER 14 DAYS

ORIGIN OF FISH # EATEN #NOT EATEN TOTAL

PC 23 7 30

TK 12 19 30

More contaminated fish are more likely to be eaten by predator, and pass contaminants up the food chain.

Blue Crabs- Callinectes sapidus

• Prey capture ability of adults from TK and contaminated Hackensack Meadowlands

• Compare predator avoidance ability of juveniles from TK and HM w. adult blue crab predators

Jessica Reichmuth

Capture of Juvenile Blue Crab Prey

Ca

ptu

re ti

me

(h

rs)

0

10

20

30

40

50

60

70

Population

HMTK

Adult Capture of Juvenile Blue Crab Prey Time to capture 2 of 4 juveniles

Capture of Mummichog Prey

0

1

2

3

4

5

6

7

8

Population

HMTK

# m

um

mic

hog

s e

ate

n

Capture of Mussel PreyT

ota

l We

t We

igh

t (g

) E

ate

n

0

5

10

15

20

25

30

35

40

45

Population

HMTK

Capture of Mussel Prey

Capture of Fiddler Crab PreyT

otal

# o

f fid

dler

cra

bs e

aten

02468

101214161820

Population

HMTK

8.7

27.35.1

0.4

3.4

0

1.5

11.4

5.7

9.8

10

32.9

22.4

0.3

32.4

7.5

10.9 10.3

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 2

Unknown

Sediment/Detritus

Plant/Algae

Fish

Unknown Crustacea

Bivalve

Polychaete

Amphipod

Crab

HM Stomachs TK Stomachs

Field: Stomach Contents

HM Transplants to TK or fed clean TK food in the lab: Capture of

juvenile blue crabs

0

10

20

30

40

50

60

70

Treatment

HM (base)

HM:TK

HM + TK food

Tim

e to

co

nsu

me

50

% p

rey

(hrs

)

A

B B

TK Transplants to HM or fed HM food (killifish) in lab: capture of

juvenile blue crabs

Tim

e to

co

nsu

me

50

% p

rey

(hrs

)

0

50

100

150

200

250

Treatment

TK (base)

TK:HM

TK + HM foodA

B

C

Reichmuth et al. ’09 Estuar Coast.

Predator Avoidance Results

To

tal #

su

rviv

ors

0

5

10

15

20

25

30

35

40

Population

HMTK

Predator (adult Blue Crab) Avoidance by Juveniles

Bluefish (Pomatomus saltatrix) studies:

A temporary resident

Allison Candelmo

Spawn in the ocean and then move into estuaries in the Spawn in the ocean and then move into estuaries in the spring. spring. Spend critical periods of growth and development during Spend critical periods of growth and development during first summer before going to the ocean for the winterfirst summer before going to the ocean for the winter

What happens when they spend this first summer in contaminated estuaries?

Trophic Transfer Experiments

• Collect 60 YOY bluefish from Tuckerton in early summer as they enter the estuary• Feed frozen and live Brevoortia and Fundulus from either

Hackensack or Tuckerton (control) for 4 months in the laboratory

• Quantify feeding and swimming activity• Sacrifice fish and length and weight recorded• Analyze Laboratory bluefish for PCBs and Hg

Feeding experiments after eating TK or HM food for 4 months

TKfed - up to 5x fasterConsumption rate TKfed - up to 2x more food consumed

Time Required to Consume Ration

0

2

4

6

8

10

12

14

16

1 2 3

Trial

Sec

onds

TuckertonHackensack

Amount of mummichogs consumed

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 1 2 3 Tuckerton Hackensack#

cons

umed

per

blu

efis

h

a

b

Swim Rate

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 1 2 3Tuckerton Hackensack

Rat

e (m

/s)

Swimming activity

Poorer schooling – more milling about – would make them more susceptible to predation

Candelmo et al. 2010 Est. Coasts

Size Distribution

PCB levels in mummichogs (Fh) and menhaden (Bt) from bluefish stomachs vs collected in nets

Field Bluefish in Hackensack

• Smaller than at Tuckerton in the fall when it is time to migrate back to the ocean

• Most with empty stomachs • Contaminants like PCBs and mercury are

biomagnified in bluefish over levels in their prey. • Fish with higher levels of contaminants are more

impaired, more likely to be captured and transfer more contaminants to predators such as birds.