Transcript THE RELATIONSHIP BETWEEN RIBBED MUSSEL (GEUKENSIA

The Relationship Between Ribbed Mussel (Geukensia demissa)
Density and Salt Marsh Shoreline Erosion
Joshua Moody1 , David Bushek1 and Danielle Kreeger2
1Rutgers, Haskin Shellfish Research Laboratory, Port Norris, NJ
2Partnership for the Delaware Estuary Wilmington, DE
Introduction
Preliminary Results
A
 Increasing storm severity, boat wakes, and
sea-level rise threaten salt marshes. (A)
Erosion as a Function of Percent Mussel Cover
 The synergistic relationship between the
ribbed mussel Geukensia demissa and
Spartina alterniflora may provide some
protection.
 Deposition of nutrient rich feces from
mussels enhances production of S.
alterniflora creating levees along the marsh
edge which trap sediments, enhancing
vertical accretion. (Bertness, 1984)
B
 Marsh shoreline erosion precludes levee
formation.
 The physical structure formed by mussel
aggregations may provide stability to the
marsh edge (B), but data are lacking.
Hypothesis: Within an energy regime, salt marsh shoreline erosion
decreases as mussel density increases.
Methods

Twelve 150m study sites in four tributaries of the Delaware Estuary
(3 per tributary). (A)
 Site 1 is located at tributary mouth.
 Site 2 is located above first meander.
 Site 3 is located up river where wave action is lower.
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Each site was demarcated with 31 transects located five meters
apart along the marsh edge.

A permanent post was placed 1 m back from the marsh edge at
each transect.
A
B
 Contrary to our expectiatons, preliminary data from these six sites suggest only the slighest relationship
between erosion and percent mussel cover. As data from six more study sites are incorporated, more
prominent trends may emerge.
Objective 1: Quantify Mussel Demographics (Bertness and
 These data do not consider mussel density, mussel demographic, or mass transport rates.
Grosholz, 1985): percent mussel cover quantified at each
transect; ten 25cm 2 samples excavated for mussel density and
demographic analysis. (B)
Objective 2: Quantify Mass Transport Rate of Water (Yokoyama et
al 2004): dissolution rates of plaster-o-paris hemispheres (clods)
measured at each transect . (C)
 Percent mussel cover, mass transport and erosion will be investigated using multivariate statistical analysis
in order to analyze the potentially complex relationship between them.
C
 Regardless of the relationship between ribbed mussels and erosion, ribbed mussels may provide several
other valuable ecosystem services such as levee formation, nutrient cycling, biological filtration, and
increasing habitat complexity.
Objective 3: Quantify Lateral Marsh Movement: Change in the
position of the marsh edge from each permanent transect post
was measured after one year . (D)
Analysis: Lateral marsh movement, mussel density, and
mass transport rate will be compared within sites, among
sites and among tributaries using standard statistical
analysis (correlation, regression, ANOVA, and ANCOVA).
Literature Cited
D
Bertness, M.D. 1984. Ribbed Mussels and Spartina
alterniflora production in a New England salt marsh.
Ecology. 65(6): 1794-1807.
Bertness, M.D. and E. Grosholz. 1985. Population dynamics
of the ribbed mussel, Geukensia demissa: The costa and
benefits of an aggregated distribution. Oceologica,
67:192-204.
Yokoyama, Hisashi, Misa Inoue, and Katsuyuki Abo. 2004.
Estimation of the assimilative capacity of fish-farm
environments based on current velocity measured by
plaster balls. Aquaculture, 240: 233-247.
Funding Provided By
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National Shellfisheries Association
Delaware National Estuarine Research
Reserve
Society of Wetlands Scientists
National Fish and Wildlife Foundation
New Jersey Sea Grant