How long does oyster shell last on an oyster reef?

Photo courtesy of David Bushek, Haskin Shellfish Research Laboratory

John N. Kraeuter, Eric N. Powell and Kathryn A. Ashton-Alcox Haskin Shellfish Research Laboratory, Rutgers University

Photo courtesy of David Bushek, Haskin Shellfish Research Laboratory

39.1

39.2

39.3

39.4

39.5

39.1

39.2

39.3

39.4

39.5

75.5 75.4 75.3 75.2 75.1

75.5 75.4 75.3 75.2 75.1

Round Island

Upper Arnolds

Arnolds

Upper Middle

Middle

Shell Rock

Ship John

Cohansey

Nantuxent

Bennies

Bennies Sand

Vexton

Egg IslandLedge

New Beds

BeadonsHawk's Nest

StrawberryHog Shoal

6.5 - 14.5 ppt

9.0 - 16.5 ppt

14.0 - 20.0 ppt

17.0 - 22.5ppt

UPPER

UPPER CENTRAL

CENTRAL

LOWER

Sea Breeze

Delaware Bay Oyster Seed Beds

0

100

200

300

400

500

600

700

800

900

1000

53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 1 3 5

Year

Average number per bushel

Oyster Spat Mean Oyster Mean Spat

1758

Delaware Bay Oyster

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 1 3 5

Ratio

Mortality Mean mortality

Recent Box Counts from the monitoring program. Depict the of relatively low constant rate of new boxes following major input from 2002, and lack of recruitment. It is data such as this that allows estimating loss rate of boxes into cultch.

Average Seedbed Recent Boxes

0

5

10

15

20

25

Jan-02Apr-02Jul-02Oct-02Jan-03Apr-03Jul-03Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05Apr-05Jul-05Oct-05Jan-06Apr-06Jul-06Oct-06Jan-07Apr-07

% of Recent Boxes in Sample

dS/dt = (b(t) - L)S

b(t) S

LS

Taphonomic attack on shellin the Delaware Bay

Cliona - yellow boring sponge

Cliona + redbeard sponge

Cliona + calcareous tube worms

Urosalpinx - oyster drill

Drilled oyster spat

Cliona + worm burrows

Blue Crab - Callinectes sapidus

1998 1999 2000 2001 2002 2003 2004 2005

0.0x100

2.0x108

4.0x108

6.0x108

8.0x108

1.0x109

1.2x109

1.4x109

1.6x109

Middle

Cohansey

Ship John

New Beds

Beadons

1998 1999 2000 2001 2002 2003 2004 2005

0.0x100

2.0x108

4.0x108

6.0x108

8.0x108

1.0x109

1.2x109

1.4x109

1.6x109

2.2x109

2.4x109

Middle

Cohansey

Ship John

New Beds

Beadons

Num

ber

of S

pat

Num

ber

of O

yste

rs

1998 1999 2000 2001 2002 2003 2004 2005

0

2

4

6

8

10

12

14

16

18

20

22

Middle

Cohansey

Ship John

New Beds

Beadons

Cul

tch

(L m

-2)

39.1

39.2

39.3

39.4

39.5

39.1

39.2

39.3

39.4

39.5

75.5 75.4 75.3 75.2 75.1

75.5 75.4 75.3 75.2 75.1

Round Island

Upper Arnolds

Arnolds

Upper Middle

Middle

Shell Rock

Ship John

Cohansey

Nantuxent

Bennies

Bennies Sand

Vexton

Egg IslandLedge

New Beds

BeadonsHawk's Nest

StrawberryHog Shoal

Sea Breeze

New Jersey

Delaware

Delaware Bay

Doubling times and half-lives of shell on New Jersey oyster beds

for the time period of 1998 to 2005

Years

Beadons

New Beds

Bennies

Bennies Sand

Shell Rock

Ship John

Cohansey

Middle

Arnolds

0 2 4 6 8 10 12 14

Half LIfeDoubling Time i

39.1

39.2

39.3

39.4

39.5

39.1

39.2

39.3

39.4

39.5

75.5 75.4 75.3 75.2 75.1

75.5 75.4 75.3 75.2 75.1

Round Island

Upper Arnolds

Arnolds

Upper Middle

Middle

Shell Rock

Ship John

Cohansey

Nantuxent

Bennies

Bennies Sand

Vexton

Egg IslandLedge

New Beds

BeadonsHawk's Nest

StrawberryHog Shoal

Sea Breeze

New Jersey

Delaware

Delaware Bay

Beadons

New Beds

Bennies

Bennies Sand

Shell Rock

Ship John

Cohansey

Middle

Arnolds

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40

Time-1

Loss RateAddition Rate

Addition and loss rates of shell on New Jersey oyster beds for the time period of 1998-2005

Summary• The recent 6 consecutive years of low recruitment has

allowed us to estimate the loss rate of oyster shell on beds in Delaware Bay.

• Shell loss rates were unexpectedly high – half the shell added to a bed in Delaware Bay is lost over the next 2-10 years.

• Minimal shell doubling times under the assumption of no shell loss (maximum accretion) vary from less than an decade to more than twenty years.

• The rarity of documentation of shell accumulation (vertical or lateral expansion of reefs) suggests that most shell does not remain recognizably intact for long.

• On the scale of oyster generation times, shell doubling times are not rapid.

• Projects need to consider the shell budget when presenting various restoration options.