Beck and La Peyre: Effects of oyster harvesting activities on Louisiana reef habitat and resident nekton communities 
329 
94°0'0"W 
93°0'0"W 
92°0'0"W 
91 WW 
31°0'0"N- 
-31°0’0"N 
Texas 
Louisiana 
Mississippi 
30°0'0"N- 
Sabine 
Lake 
S 
Calcasieu Lake 
(northern) 
y 
“30°0'0"N 
Calcasieu Lake 
(southern) 
O Nonharvested reef areas 
# Actively harvested reef areas 
Sister 
(Caillou) Lake 
29°0'0"N- 
0 15 30 60 
90 120 
I kilometers 
-29°0'0"N 
94°0'0"W 
93°0'0"W 
92 <5 0’0"W 
91 WW 
Figure 1 
Map of the locations of the 4 sites, Sabine Lake, Sister Lake, and northern and 
southern Calcasieu Lake, in coastal Louisiana where data were collected in 2010 
to describe oyster reef characteristics and associated resident reef community. 
the number of trays successfully retrieved (for summer 
sites: 2 treatmentsx3 sample stationsx3 traysx2 sam- 
ple events=36 samples planned; for fall sites: 2 treat- 
mentsx3 sample stationsx4 traysx2 sample events-48 
samples planned). 
Resident nekton Resident nekton were sampled by us- 
ing a benthic sample tray with an added mesh draw- 
string bag that was pulled closed before tray retrieval to 
prevent escape of mobile organisms. Trays are frequent- 
ly used to sample oyster reef residents (Lehnert and Al- 
len, 2002; Yeager and Layman, 2011) because of the im- 
practicality of using nets to capture the cryptic species 
that live within the complex oyster reef matrix. Trays 
consisted of 0.22-m 2 plastic trays (0.47 mx0.47 mx0.08 
m), which had their sides and bottoms lined with 3-mm 
mesh (Fig. 3). At deployment, trays were filled with lo- 
cal oyster reef substrate collected with a small dredge 
at adjacent reefs more than 100 m from sampling sta- 
tions and with the amount needed to displace 5.0 L of 
water volume. The volume of 5.0 L was chosen because 
it completely fills the tray with substrate. 
Deployment times ranged from 1 to 3 weeks be- 
cause weather affected our ability to retrieve the trays. 
Lehnert and Allen (2002) and others have found that 
tray soak times of 2-7 days were adequate for sam- 
pling resident nekton at subtidal oyster shell habitats 
and that the communities recruited to trays did not 
change significantly after 7 days. 
Upon retrieval, all organisms were collected, placed 
on ice, and taken to the laboratory, where they were 
identified with the use of field guides to the lowest 
practical taxon (Felder, 1973; Thompson, 1986; Hopkins 
et al, 1987; Hoese and Moore, 1998; Kells and Carpen- 
ter, 2011), measured (total length in millimeters for fish 
and shrimp, carapace width in millimeters for crabs, 
and wet-weight in grams), and frozen at a tempera- 
ture of -20°C. If a tray was dumped during retrieval 
( i.e. , some tray contents were lost because of improper 
net function), organisms were still collected and identi- 
fied for possible use during stable isotope analyses but 
were not included in species abundance comparisons. 
All data for densities of organisms are reported as the 
number of individuals per square meter. 
Reef structure Reef composition was determined by 
counting and measuring material placed in each tray 
before deployment. Volume of loose shells and shell 
clusters was measured by water displacement. Shell 
clusters were defined as having a minimum of 3 fused 
oyster shells. The volume of loose shells and clusters 
provides a proxy for the availability of small and large 
