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3. Quahog Condition Index
5
in the Providence River has been found to be low Marroquin-Mora and Rice 2008; the authors note that the area containing clams with the lowest Condition Index coincides
with the area that experiences frequent hypoxic
6
conditions. 4.
From a survey of quahogs in Greenwich Bay, Lazar et al. 1994 report a broad range of quahog sizes, with some areas showing signs of poor recruitment years as evidenced by adults of different
ages spanned by years with no representative age classes. The authors found that areas closed to harvest had high densities of clams 0–17.9 m
-2
in open areas vs. 0.2–33.9 m
-2
in closed, and suggest that Greenwich Cove, Warwick Cove, Brushneck Cove, and Apponaug Cove provide the broodstock
for the Greenwich Bay quahog population. 5.
The RI DEM dredge survey reports Greenwich Cove as having a quahog density of 12 clams m
-2
, Warwick Cove 30 m
-2
, Apponaug Cove 16 m
-2
, and Greenwich Bay proper 4 m
-2
Lazar et al. 1994. Rice et al. 1989 report quahog densities of 190 clams m
-2
in Greenwich Cove mean width 61 mm, and 78 clams m
-2
in Greenwich Bay mean width 31 mm.
5
Condition Index of bivalves relates the proportion of the shell cavity that is occupied by soft body tissue, and are often used to follow seasonal change in nutrient reserves or meat quality Dame 2012. Low Condition Index e.g.,
less meat inside the shell, indicates some stressors that are causing the shellfish to not grow to its fullest potential. Predator presence, lack of food, or presence of pollutants, for instance, could be mechanisms that reduce growth and
lead to reduced bivalve Condition Index.
6
When experiencing hypoxic conditions, most bivalves “clam up,” shutting the shell tightly with a cessation of pumping water and filter feeding Dame 2012. Since the bivalve is no longer actively feeding and respiring, stress
sets in and overall growth and condition is reduced.
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18, 2014
Figure 2.3 3. Distribution
C
HAPT
of legal-sized Rhode Is
TER
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hard clams in sland Shellfis
GY
Narragansett B sh Manageme
Bay RIDEM 2 ent Plan, Vers
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73
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308 Figure 2.4. Rh
hode Island De t Plan, Versio
C
HAPT
epartment of E on II
TER
2: E
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Environmental M
GY
Management S
N
OV
Shellfish Harve
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18, 201
est Areas.
14
N
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6. Due t
quaho saw q
7. Based
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1983; Salt P
220.2
F
220.2
1. The ra
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R
18, 2014
o its warming og spawn Ma
quahog spawn d on modeling
agansett Bay, Larval transpo
Narragansett B 4 of larvae
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Most of the lar ignificant tran
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with small num Larvae release
umbers movin emaining in th
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umbers on the o the open oce
ogs were foun d, with greate
of Harris Poi ; 1992 and G
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2. Eastern o
Figure 2.5. Eas
2.1. Ecology
ange of the E ida and into t
g sooner than arroquin-Mor
n sooner than g efforts to sim
Leavitt et al. rt from the Pr
Bay, with mor were transpo
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ed out of the rvae released
nsport into the n.
rvae were larg mbers remaini
d at Hog Islan ng into the Ea
he upper Bay ean.
d at Rocky Po e west side of
ean. nd by Campb
st densities fo int, in Cormo
Ganz et al. 20
yster Crass
stern oyster C astern oyster
the West Indi
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other waters, ra and Rice 20
cool water co mulate the tra
2013 identi rovidence Riv
re larvae endi rted out of th
wning sanctua gnificant num
bay to the op in Greenwich
e West Passag gely transpor
ing in the low nd saw wide
ast Passage an and West Pa
oint were pre f the East Pas
bell 1961 to ound in the so
rant Cove and 000 all report
sostrea virgi
Crassostrea virg is from the G
ies, in estuarin Rhode Is
TER
2: E
COLOG
, Greenwich C 008. Butet 1
oves. ansport and di
ify the follow ver area show
ng up in the W e bay to the o
ary at the mou mbers moving
en ocean. h Cove were r
ge; 11–21 o rted out of Na
wer East and W distribution th
nd into Moun ssage; 35–46
dominantly fo ssage; 34–43
be the predom outhwest regio
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inica
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ne waters inte sland Shellfis
GY
Cove is repor 1997 similarl
istribution of wing findings:
wed wide disb West Passage
open ocean. uth of Greenw
g into the Wes retained in Gr
of larvae were arragansett Ba
West Passage hroughout Na
nt Hope Bay, of larvae w
found in the W of larvae w
minant bivalv on. Russell et
orth shore of to be the mos
ation courtesy wrence Cana
ertidally to 30 sh Manageme
rted as being t ly noted that w
f quahog larva bursement thro
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st Passage; 45
reenwich Bay e transported
ay to the open es.
arragansett B and significa
were transport West Passage,
were transporte ve in Great Sa
t al. 1973 re f Great Salt Po
st abundant bi
of Brandon Fu ada south to
0 m Coen an ent Plan, Vers
P
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OF
37 the first area t
warm water c
ae throughout oughout
st Passage; 20 ded to remain
5–51 of larv y, but with
out of the bay n ocean 95–9
ay, with large ant numbers
ted out of the , with small
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bay lock
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at
e 07.
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2. The Eastern oyster was an important food source for Native Americans and early settlers to Rhode
Island. Goode 1887 notes that oysters were overfished in Narragansett Bay by the late 1880s, and natural harvest gave way to broad scale oyster aquaculture Desbonnet and Lee 1991. Wild harvest
of oysters today is sporadic Figure 2.6, though a robust aquaculture industry for oysters is present, particularly in the south shore coastal lagoon ecosystems.
3. Oysters have been commercially extinct in Narragansett Bay for decades, and those few wild
populations that were observed in the 1990s appear to have succumbed to disease andor over exploitation Oviatt et al. 2003. Oysters once were common in the south shore lagoon ecosystems as
well. Lee 1980 ties the loss of oysters in the salt ponds to the installation of permanent breachways.
4. Oyster reefs provide valuable ecosystem services, which have been summarized as: 1 oyster
production, 2 water filtration and biodeposits concentration, 3 habitat provision, 4 carbon sequestration, 5 fishing resource augmentation, 6 stabilization of benthic and intertidal habitat, and
7 increased landscape diversity Coen et al. 2007; Grabowski and Peterson 2007. zu Ermgassen et al. 2013 estimate a 64 decline in non-aquaculture oyster extent and an 88 loss of non-
aquaculture oyster biomass in the United States between the early 1900s and the early 2000s, noting that this loss can be linked to observed water quality andor habitat degradation.
5. The oyster is a reef building species, and reef structure influences local ecological conditions. A
correlation between height of an oyster reef above bottom and oyster growth rate has been reported Schulte et al. 2009. Flow rates are increased at height, replenishing food and rapidly removing
wastes, resulting in increased oyster growth.
N
OVEMBER
Figure 2.
220.2
1. From
for oy habita
ppt, d 0.5–3
low d
2. Oyste
in late et al.
aquac
3. Brow
reache Easter
7
The oyste establishin
5 10
15 20
25
T h
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a
2 4
6 8
10 12
14 16
T h
ou san
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O ys
te rs
b
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18, 2014
6. Eastern oys
