The relative role of nutrients, grazing, and predation as controls on macroalgal growth in the
Waquoit Bay estuarine system
Sophia E. Fox 1,2, *, Mirta Teichberg 3 , Ivan Valiela 2 , and Leanna Heffner 4
1
Cape Cod National Seashore, National Park Service, Wellfleet, Massachusetts, 02667, U.S.A.
2 The Ecosystems Center, Marine Biological Laboratory, Woods Hole, Massachusetts, 02543,
U.S.A.
3 Zentrum für Marintropenökologie, Bremen, 28359, Germany.
4
Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island,
02882-1197, U.S.A.
*Corresponding author: Sophia_Fox@nps.gov, telephone: 508-487-3262 x109, fax: 508-487-
7153

2
ESM 1. List of references used to determine trophic classifications of taxa found in experimental cages.
Alon, N.C. and S.E. Stancyk. 1982. Variation in life-history patterns of the grass shrimp
Palaemonetes pugio in two South Carolina estuarine systems. Marine Biology 68:265-276.
Duffy, J.E. and M.E. Hay. 1994. Herbivore resistance to seaweed chemical defense: The roles of mobility and predation risk. Ecology 75:1304-1319.
Fox, S.E., M. Teichberg, Y.S. Olsen, L. Heffner, and I. Valiela. 2009. Restructuring of benthic communities in eutrophic estuaries: Lower abundance of prey leads to trophic shifts from omnivory to grazing. Marine Ecology Progress Series 380:43-57.
Graham, S., J. Davis, L. Deegan, J. Cebrian, J. Hughes, and J. Hauxwell. 1998. Effect of eelgrass
( Zostera marina ) on the feeding efficiency of mummichog ( Fundulus heteroclitus ).
Biological Bulletin 195:241-243.
Hauxwell, J., J. McClelland, P.J. Behr, and I. Valiela. 1998. Relative importance of grazing and nutrient controls of macroalgal biomass in three temperate shallow estuaries. Estuaries
21:347-360.
Heck, Jr., K.L. and T.A. Thoman. 1981. Experiments on predator-prey interactions in vegetated aquatic habitats. Journal of Experimental Marine Biology and Ecology 53:125-134.
Heckscher, E., J. Hauxwell, E.G. Jimenez, C. Rietsma, and I Valiela. 1996. Selectivity by the by the herbivorous amphipod Microdeutopus gryllotalpa among five species of macroalgae.
Biological Bulletin 191:324-326.
Kneib, R.T. 1985. Predation and disturbance by grass shrimp, Palaemonetes pugio Holthius, in soft-substratum benthic invertebrate assemblages. Journal of Experimental Marine Biology and Ecology 93:91-102.

MacNeil, C., J.T.A. Dick, and R.W. Elwood. 1999. The dynamics of predation on Gammarus spp. (Crustacea: Amphipoda). Biological Reviews 74:375:395.
Martinetto, P., M. Teichberg, and I. Valiela. 2006. Coupling of estuarine benthic and pelagic food webs to land-derived nitrogen sources in Waquoit Bay, Massachusetts, USA. Marine
Ecology Progress Series 307:37-48.
McClelland, J.W. and I. Valiela. 1998. Changes in food web structure under the influence of increased anthropogenic nitrogen inputs to estuaries. Marine Ecology Progress Series
168:259-271.
McCurdy, D.G., M.R. Forbes, S.P. Logan, D. Lancaster, and S.I. Mautner. 2005. Foraging and impacts by benthic fish on the intertidal amphipod Corophium volutator . Journal of
Crustacean Biology 25:558-564.
Morgan, M.D. 1980. Grazing and predation of the grass shrimp Palaemonetes pugio . Limnology and Oceanography 25:896-902.
Nelson, W.G. 1979. Experimental studies of selective predation on amphipods: Consequences for amphipod distribution and abundance. Journal of Experimental Marine Biology and
Ecology 38:225-245.
Zimmerman, R., R. Gibson, and J. Harrington. 1979. Herbivory and detritivory among gammaridean amphipods from a Florida seagrass community. Marine Biology 54:41-47.
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ESM 2. Results of one way ANOVAs to examine effects of mesh size treatments on the growth of the macroalgae, Ulva lactuca , Cladophora vagabunda , and Gracilaria tikvahiae , within each of the three estuaries with different long-term nutrient regimes.
Estuary
High N load
Source df MS F
U. lactuca
Mesh size
Error
C. vagabunda
Mesh size
G. tikvahiae
Error
Mesh size
Error
3
12
3
12
3
12
3447.39
772.07
318.84
282.99
1360.05
295.33
4.47
1.13
4.61
Med N load
U. lactuca
Mesh size
Error
C. vagabunda
Mesh size
G. tikvahiae
Error
Mesh size
Error
Low N load
U. lactuca
Mesh size
Error
C. vagabunda
Mesh size
Error
G. tikvahiae
Mesh size
Error
3
12
3
12
3
12
3
12
3
12
3
12
3538.96
1129.44
143.00
324.06
2361.77
359.21
3.13
0.44
6.58
14432.67
10.55
1368.71
396.79
303.45
1.31
7473.24
7643.42
0.98
p
0.025
0.377
0.023
0.066
0.728
0.007
0.001
0.317
0.436
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ESM 3. Results of one way ANOVAs to examine effects of mesh size treatments on number of consumers in cages within each of the three estuaries with different long-term nutrient regimes.
Estuary Source df MS F p
High N load
Mesh size 3 1430.06
5.44
0.014
Error 12 262.77
Med N load
Mesh size
Error
3
12
375.31
262.54
1.43
0.283
Low N load
Mesh size
Error
3
12
13019.63
10.55
1235.15
0.001
5