Reef-associated fauna in Chesapeake Bay: Does oyster species affect habitat function? H. Harwell* 1, P. Kingsley-Smith 2, M. Kellogg 3, K. Paynter, Jr.
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Reef-associated fauna in Chesapeake Bay: Does oyster species affect habitat function?
H. Harwell*H. Harwell*11, P. Kingsley-Smith, P. Kingsley-Smith22, M. Kellogg, M. Kellogg33, , K. Paynter, Jr.K. Paynter, Jr.33 and M. Luckenbach and M. Luckenbach11..
11Virginia Institute of Marine Science, The College of William & Mary Virginia Institute of Marine Science, The College of William & Mary 22South Carolina Department of Natural Resources,South Carolina Department of Natural Resources,33University of Maryland University of Maryland
• Macroinvertebrate densities and species richness are generally positively correlated with structural complexity (Crowder and Cooper 1982, Diehl 1992).
The Role of Habitat Complexity:
• Structurally complex habitats offer a greater variety of different microhabitats and niches, allowing more species to co-exist and contribute to within habitat diversity (Pianka 1988, Levin 1992).
• The importance of habitat heterogeneity / complexity has been investigated in many marine systems, including coral reefs, seagrass beds, rocky intertidal, mangroves, macroalgae, and oyster reefs.
C. virginica C. ariakensis
Photo credits: Mark Luckenbach
C. ariakensis
C. sikamea
Does habitat complexity vary between oyster species?
If so, how will these differences affect habitat utilization?
Compare the complexity of experimental Compare the complexity of experimental C. ariakensisC. ariakensis and and C. virginicaC. virginica reefs by examining vertical relief and surface reefs by examining vertical relief and surface complexity.complexity.
Evaluate and compare the utilization of experimental Evaluate and compare the utilization of experimental C. C. ariakensisariakensis and and C. virginicaC. virginica reefs by other organisms. reefs by other organisms.
Investigate the relationship between the development of Investigate the relationship between the development of reef associated communities and habitat complexity.reef associated communities and habitat complexity.
ObjectivesObjectives
Experimental Design
• 4 sites in Chesapeake Bay
• 4 experimental “reef” treatments at each site:
- triploid C. virginica only
- triploid C. ariakensis only
- 50% C. v. & 50% C. a
- Shell only
• 2 replicates of each treatment per site
• Treatments placed in cages for biosecurity
• Each cage has a matrix of 5 x 5 trays
Atlantic OceanAtlantic Ocean
Che
sape
ake
Bay
Che
sape
ake
Bay
Delaware Delaware BayBay
SEVERN RIVERSEVERN RIVERSubtidal (3 - 4m)Low salinity (3 - 14 mean daily psu)Low predation pressureLow Dermo / No MSX
PATUXENT RIVERPATUXENT RIVERSubtidal (3 - 4m)Low salinity (8 - 16 mean daily psu)Moderate predation pressureLow Dermo / No MSX
YORK RIVERYORK RIVERSubtidal (1 - 2m)Mid salinity (9 - 21 mean daily psu)High predation pressureHigh Dermo / High MSX
York (high salinity) Machipongo (high salinity, intertidal)
A A
B
Mea
n ab
unda
nce
per
gram
of
oyst
er b
iom
ass
Factor F p Tukey Comparisons
Site 23.97 <0.0001 MachipongoA, PatuxentB, YorkB, SevernB
Treatment 6.00 0.0045 C.v.A, C.a.B, mixB
Site*Treatment 5.25 0.0003 Treatment effects driven by PR and YR sites
Standardized Total Abundance
Species F p Tukey Comparisons
C. equlibra 8.78 0.0005 C.v.A mixB C.a.B
C. penantis 5.78 0.0054 C.v.A mixB C.a.B
C. lacustre 8.06 0.0009 C.v.A mixAB C.a.B
E. levis 9.62 0.0003 C.v.A mixB C.a.B
G. mucronatus 8.99 0.0004 C.v.A mixB C.a.B P. tenuis 7.62 0.0012 C.v.A C.a.B mixB
D. microphthalmus 29.34 0.0001 C.v.A C.a.B mixB
H. dianthus 4.33 0.0181 C.v.A C.a.B mixB
N. succinea 7.41 0.0015 C.v.A C.a.B mixB P. gouldii 4.55 0.0150 C.v.A mixB C.a.B
C. sapidus 4.09 0.0223 C.v.A C.a.AB mixB
M. tenta 4.19 0.0204 C.v.A mixB C.a.B
M. arenaria 6.60 0.0028 C.v.A mixAB C.a.B
G. strumosus 28.82 0.0001 C.v.A mixB C.a.B
G. bosci 9.95 0.0002 C.v.A mixB C.a.B
H. hentz 3.18 0.0498 C.v.A mixAB C.a.B
B. bisuturalis 31.23 0.0001 C.v.A mixB C.a.B
C. fornicata 5.47 0.0069 C.v.A mixAB C.a.B
R. punctostriatus 11.08 0.0001 C.v.A mixB C.a.B
U. cinerea 6.57 0.0028 C.v.A mixB C.a.B
stress: 0.03
Global R: 0.349 Significance Level: 0.2%
Patuxent (mid salinity)
stress: 0.02
Global R: 0.602 Significance Level: 0.1%
York (high salinity) stress: 0.05Machipongo (intertidal)
C. ariak ensis C. virginica 50 C.ariak ensis : 50 C. virginica
stress: 0.07 Severn (low salinity)
Conclusions
• Changes in both faunal assemblages and habitat complexity indices were more pronounced between sites than within sites.
• In mid to high salinity subtidal sites, C. virginica’s ability to support higher abundances of associated fauna per unit of oyster biomass may be offset by:
• C. virginica ‘reefs’ supported higher abundances of over 20 different species of associated fauna per unit oyster biomass compared to C. ariakensis ‘reefs’.
• ‘Reefs’ containing both oyster species most often supported abundances similar to those of non-native ‘reefs’, illustrating a possible effect of multi-species reefs, should C. ariakensis be introduced.
• Higher growth rates of C. ariakensis, resulting in higher oyster biomass per area of oyster bottom.
• Higher average reef height of C. ariakensis reefs.
• ESL: Brian Barnes, Alan Birch, Reade Bonniwell, Stephanie Bonniwell, Roshell Brown, Al Curry, Sean Fate, PG Ross, Edward Smith, Jamie Wheatley
• ESL Summer Aides: Raija Bushnell, Ben Hammer, Sarah Mallette, Andrew Matkin, Andrew Wilson
• UMD: Steve Allen, Marcy Chen, Jake Goodwin, Mark Sherman, Nancy Ward