1. The Impact of Salt Marsh Restoration on Macroinvertebrate Communities
Oliviah Franke1,2, Patrick Sheldon², Robert F. Chen2
1 Portland State University, School of the Environment, Portland, Oregon
2 University of Massachusetts Boston, School for the Environment, Boston, Massachusetts
References
1) Washington, H. G. (1984). Diversity, biotic and similarity
indices: a review with special relevance to aquatic ecosystems.
Water research, 18(6), 653-694.
2) Warren, R. Scott, et al. "Salt marsh restoration in Connecticut:
20 years of science and management." Restoration Ecology 10.3
(2002): 497-513.
3) Gedan, K. Bromberg, B. R. Silliman, and M. D. Bertness.
"Centuries of human-driven change in salt marsh ecosystems."
Marine Science 1 (2009).
4) Kneib, R. T. "Patterns of invertebrate distribution and
abundance in the intertidal salt marsh: causes and questions."
Estuaries 7.4 (1984): 392-412.
5) McCutchan, James H., et al. "Variation in trophic shift for
stable isotope ratios of carbon, nitrogen, and sulfur." Oikos 102.2
(2003): 378-390.
.
Acknowledgements
• Funding was provided by the
Coastal Research in Environmental
Science and Technology (CREST)
REU site (NSF award # 1062374,
OCE-GEO/OCE/HER, PIs: Hannigan
and Christian & NSF award
#1359242, OCE-GEO/OCE/EHR, PIs:
Hannigan and Christian).
• Thank you to the UMass Boston
Environmental Analytical Facility
(EAF) for providing access to the
elemental analyzer, and to Sean
McCanty for analysis assistance
• A special thanks to Patrick Sheldon
and Alex Berry for assistance with
sampling and sample processing,
and Daniel Genest and
IanPaynter for assistance
with GIS ArcMap.
Introduction
• An understanding of benthic macroinvertebrate
communities is important because they play vital roles for
the ecosystems in which they reside, by providing a food
source for higher trophic levels, and through top-down
control of primary productivity.
• Salt marsh ecosystems offer an abundance of vital
ecosystem services. These include carbon sequestration,
flood reduction, nutrient processing and habitat for
economically important species (Warren et al. 2002,
Gedan et al. 2009).
• Restoration has impacted vegetation and carbon cycling in
the Neponset salt marsh, creating three treatments
- Impacted (IT), Restored (RT), and Dredge Spoils (DST)
• Does restoration impact macroinvertebrate
communities in a salt marsh?
- Macrroinvertebrate diversity and evenness
- C and N elemental and stable isotopes analysis
Equations
H’ Shannon-Weiner
Diversity index
E Shannon-Weiner
Evenness Index
Sj Jaccard’s similarity index
𝑯′
= −∑[𝑷𝒊 𝒍𝒏𝑷𝒊 ]
Where Pi= Number of
individuals/total individuals: relative
abundance
E=H’/(ln(TR))
Where TR= taxon richness
Sj = a/(a + b + c)
Where a = number of species
common to (shared by) quadrats
b = number of species unique to the
first quadrat
c = number of species unique to the
second quadrat (Washington 1984)
Dry samples at 60°C
Grind samples into fine powder
Weigh out samples:
2mg Veg, 0.5mg soil/animal
Fold into tin packets
Combustion for CHN
analysis
CHN analysis
1/4m² quadrats were sampled (n=5)
-all macroinvertebrates
-3 composited soil
-3 composited vegetation
Methods
Field sampling
For each treatment: restored
treatment (RT), impacted treatment
(IT), and dredge spoils treatment
(DST):
All photos taken by Oliviah Franke
Results and Discussion
Diversity
0
0.2
0.4
0.6
0.8
1
1.2
RT IT DST
H'indexvalue
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
RT IT DST
Eindexvalues
Figure 1. mean values for H’ values across each treatment with
standard error reported.
Figure 2. Mean E values across each treatment with standard error
reported
Sites
Jaccard's
index (%)
RT/IT 12.5
IT/DST 15.79
DST/RT 7.69
Site FFG
RT grazers
IT shredders/grazers
DST shredders/predators
Table 1. Jaccard’s similarity indices for three treatment
comparisons
Table 2. Dominant FFG for each treatment
• There was a significant difference in Shannon index values across treatments
as indicated by ANOVA results (F(2,12)=3.3, P=0.073), as well as in evenness
values across treatments (F(2,12)=3.9. p=0.051).
• Functional feeding groups (FFG) of the
dominant taxa for RT differed from IT and
DST.
• IT and DST showed shredders as dominant
FFG
• When analyzing community structure, index
values only show a small portion of the big
picture.
• Consideration of functional feeding groups as
well as similarity in composition to natural
systems indicates successful restoration
• Despite lower H’ and E in the restored treatment, the community was
representative of natural salt marsh systems as indicated by prior research
(Kneib 1984).
• Taxon included Melampus bidentatus, orchestia grillus, and
Sesarma reticulum
site mean C/N st. dev
PLANTS
IT 34.6 24.3
DST 406.2 550.2
RT 213.9 116.5
ANIMALS
IT 8.6 2.9
DST 9.2 0.9
RT 11.6 2.8
SOILS
IT 21.6 16.9
DST 32.6 7.7
RT 21.9 3.2
C/N ratios
Isotope analysis
0.1
0.2
0.3
0.4
0.5
0.6
0.7
-32 -27 -22 -17 -12
δN
δC
Restored: S. alterniflora
Impacted: P. australis
Dredge Spoils
SOILS
ANIMALS
PLANTS
Figure 4. Study site. Neponset salt marsh in Boston Massachusetts.
Red=restored treatment (RT), blue=impacted treatment (IT), yellow=dredge
spoils (DST).
• More sampling- seasonality, increase n, other systems
• Sample for marine influence on trophic web (RT)
• Carbon analysis by species (e.g. Functional Feeding
Groups)
• Follow changes in trophic web after restoration
• Assess denitrification in DST soil
• IT plants showed the lowest C/N ratios, where as DST plants had the
highest ratios.
• Differences in C/N in plants due to difference in C₃ and C₄ plants
S. alterniflora = C₄, P. australis=C₃, DST most likely C₃
• High variance in plant samples could be reduced with consistent
sampling, live vs. dead
• High C/N ratios in DST soil indicate a loss of N after restoration
-Denitrification  flying, leaching
• RT soils very consistent, IT soil very variable
• Lower C/N in animals expected due to protein richness
• “You are what you eat plus one” (McCutchan et al. 2003), for
carbon in consumers
• Restoration has separated the trophic web of RT from DST and IT
• Restoration created a monoculture of S. alterniflora
• Animals in each treatment are eating locally
-RT specialized feeding
-Possible marine input of food source for RT, shifting the C for
animals
• The visible separation of RT correlates with a 15.79% similarity in
macroinvertebrates between IT and DST (Table 1.)
Future research
Figure 3. Carbon and Nitrogen isotope analyses for the Neponset salt marsh.
Table 3. Elemental analysis results