Effects of Oil Exposure on Submerged Aquatic Vegetation Growth, Reproduction, and Herbivory Charles W. Martin University of Florida/IFAS Nature Coast Biological Station
• Estuaries in the Gulf of Mexico provide much of the nation’s supply of fisheries , wetlands , & numerous desirable natural resources From Lellis-Dibble et al. 2008
Deepwater Horizon Oil Spill Photo: Coxworth http://gomex.erma.noaa.gov/ Photo: Beinecke
• Effects of Oil on Submerged Aquatic Vegetation • Growth • Reproduction • Root Morphology • Food Web Effects of Plant Oiling • Herbivory of oil-affected plant tissue • Future food web work
Widgeon grass, Ruppia maritima • Coastal vegetation Lacombe, LA provides numerous ecosystem services • Refuge for nekton • Forage base for Cocodrie, LA organisms • Buffer from storms • Water filtration Port Sulphur, LA
Studies have focused on oil effects to emergent vegetation , while much less is known about submerged vegetation From Pezeshki et al. 2000
1. What are the effects of oil on Ruppia maritima ? 2. Are there food web implications from this oil exposure?
• Ruppia grown in 19L tanks at 10 psu for 31-33 days • 4 randomized treatments: (0mL) (5mL) (10mL) (20mL) • Tanks contained 2L of sediment and n=12/treatment • In tanks containing oil, a layer was buried ~3cm deep before planting
Flowers Reproduction Growth Fruiting Bodies Root Characteristics
1. Growth (proportional change in weight, number of shoots)
1. Growth Wet Weight p=0.494 0.10 0.08 Change/day (+1SE) 0.06 0.04 0.02 0.00 None Low Medium High Number of Shoots p=0.737 0.30 0.25 Change/day (+1SE) 0.20 0.15 0.10 0.05 0.00 None Low Medium High
Flowers 2. Reproduction (proportional change in number of flowers, fruits) Fruiting Bodies
2. Reproduction Flowers Flowers p=0.008 0.5 A Change/day (+1SE) 0.4 A,B A,B 0.3 B 0.2 0.1 0.0 None Low Medium High Fruit 1.6 p=0.015 A 1.4 1.2 Change/day (+1SE) 1.0 A,B 0.8 Fruiting B B 0.6 Bodies 0.4 0.2 0.0 None Low Medium High
3. Root Characteristics (mass, length, diameter, area, uprooting strength)
Root Area p=0.015 Root Mass p=0.686 8 0.20 B A,B Area (mm2+1SE) Mass (mg+1SE) 6 0.15 A,B A 4 0.10 NO OIL HIGH OIL 2 0.05 0 0.00 None Low Medium High None Low Medium High Root Length 120 p=0.05 p=0.021 Root Diameter 0.5 A B 100 A,B Length (mm+1SE) A,B Diameter (mm+1SE) 0.4 A,B A 80 A,B B 0.3 60 0.2 40 20 0.1 0 0.0 None Low Med High None Low Medium High
Uprooting Strength p<0.001 250 A 200 A Grams of Force (+1SE) B 150 B 100 50 Silliman et al. 2012 0 None Low Medium High Turner et al. 2016
The link between C:N and Herbivory C:N Ratio Citation Plant Herbivore 30 A p= 0.006 Kraft & Denno 1982 Shrub Insects Coley 1983 Terrestrial trees Insects C:N Ratio (+1SE) 28 Schroeder 1983 Terrestrial tree Insects A,B Onuf et al. 1977 Mangroves Insects Herbivores prefer 26 Various marine A,B Lilly 1975 Urchins plants plants with high 24 Bjorndal 1980 Seagrass Green turtle B Zieman et al. 1984 Seagrass Green turtle nitrogen content 22 Williams 1988 Seagrass Green turtle McGlathery 1995 Seagrass Fishes 20 None Low Medium High Preen 1995 Seagrass Dugong Valentine & Heck 2001 Seagrass Urchins Treatment Goecker et al. 2005 Seagrass Fishes Oil Exposure = Lower C:N!
• Laboratory herbivory assays • Leaf tissue imbedded in agar matrix (Hay et al. 1984, Valentine & Heck 2001, Goecker et al. 2005, Prado & Heck 2011) • Herbivores: • Grass shrimp (x5) ( Paleomonetes pugio ) • Amphipods (x10) ( Gammarus mucronatus)
Experiment 1 Experiment 2 Paired Choice Experiment Foraging Rate Experiment p=0.19 p=0.49 0.5 0.5 0.4 0.4 None Low 0.3 0.3 0.2 p<0.01 vs vs 0.2 A None A 0.20 0.1 0.1 Low Medium 0.0 0.0 0.15 -0.1 Proportion Loss None Low Low Medium B Low 0.5 p=0.04 * 0.5 p<0.01 * Proportion Loss 0.10 B None Low 0.4 0.4 0.3 0.3 vs vs 0.05 0.2 0.2 Medium Medium 0.1 High 0.1 0.00 0.0 0.0 None Medium Low High None Low Medium High 0.5 p<0.01 * 0.5 p<0.01 * None Medium High Treatment 0.4 0.4 0.3 vs vs 0.3 0.2 High High 0.2 0.1 0.1 0.0 -0.1 0.0 None High High Medium All Comparisons n=12
Experiment 1 Experiment 2 Paired Choice Experiment Foraging Rate Experiment 0.12 0.12 p=0.074 p=0.79 0.10 0.10 0.08 0.08 24 Hours 48 Hours 0.06 0.06 0.04 0.04 p=0.07 0.10 p=0.01 0.02 0.02 0.12 A 0.00 0.00 A 0.08 -0.02 -0.02 None Low Low Medium 0.10 Proportion Loss A p=0.071 p=0.017 0.12 0.12 A 0.06 * 0.08 0.10 0.10 B 0.08 B 0.08 A B 0.06 0.06 0.06 0.04 0.04 0.04 0.02 0.02 0.04 0.02 0.00 0.00 -0.02 -0.02 None Medium Low High 0.02 0.00 p=0.012 p=0.03 0.12 0.12 0.10 0.00 0.10 * * None Low Medium High 0.08 0.08 None Low Medium High 0.06 0.06 Treatment 0.04 0.04 Treatment 0.02 0.02 0.00 0.00 -0.02 -0.02 None High Medium High All Comparisons n=12
Food Web Resilience to Oil Variable effects of DWH on populations - + no effect Small fish Insects Large fish Able et al. 2015 Fodrie & Heck 2011 McCall & Pennings 2012 McCann et al. 2017. Frontiers in Ecology and the Environment. 15(3): 142-149.
Food Web Resilience to Oil Literature Synthesis McCann et al. 2017. Frontiers in Ecology and the Environment. 15(3): 142-149.
Extirpation of most sensitive nodes oil
Extirpation of most sensitive nodes oil Unoiled Oiled 51 # Nodes 39 343 # Links 210 6.72 Link density 5.38 0.13 Connectance 0.14
1. What are the effects of oil on Ruppia maritima ? Reduced flowering, changes to root morphology, decreased uprooting force Martin, C.W., L.C. Hollis, R.E. Turner. 2015. Effects of oil-contaminated sediments on submerged vegetation: an experimental assessment of Ruppia maritima . PLoS ONE 10(10): e0138797. 2. Are there food web implications from this oil exposure? Because of changes to plant chemical composition, foraging trends were altered Martin, C.W., E.M Swenson. 2018. Herbivory of submerged aquatic vegetation Ruppia maritima . PLoS ONE 13(12): e0208463.
Acknowledgements • Funding: – T his research was made possible in part by a grant from The Gulf of Mexico Research Initiative. Data are publicly available through the Gulf of Mexico Research Initiative Information & Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org. – Northern Gulf Institute. The funders had no role in the design, execution, or analyses of this project. • Louisiana : G. Turner, K. Able, J. Fodrie, O. Jensen, P. Lopez-Duarte, M. McCann, K. Oken, J. Olin, M. Polito, B. Roberts, N. Rabalais, E. Swenson, J. Lee, C. Milan, G. Peterson, R. Shaw • Alabama: J. Valentine, K. Heck, S. Powers, S. Alford, K. Blankenhorn, T. Kauffman, L. Steele, R. Puntila, S. Sklenar, S. Madsen, M. Dueker, L. Lee
Questions? Email: charles.martin@ufl.edu
Marsh Plants Inverts Marsh fish Alter food web structure & resilience Fish predators Phytoplankton Zooplankton Planktivores
Food web importance Oil sensitivity 2017. Frontiers in Ecology and the Environment. 15(3): 142-149.
Food web importance Critically Critical sensitive for species resilience Few indirect effects Oil sensitivity 2017. Frontiers in Ecology and the Environment. 15(3): 142-149.
Literature Synthesis Critically Critical Food web importance sensitive for species resilience Few indirect effects Oil sensitivity 2017. Frontiers in Ecology and the Environment. 15(3): 142-149.
Literature Synthesis Critically Critical Diet Matrix Food web importance sensitive for 1 0 1 0 1 1 0 1 species resilience 0 0 0 0 0 1 1 1 Ecological 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 1 Network 0 0 0 0 0 1 0 0 Analysis 0 1 0 0 0 0 0 0 Few indirect 0 1 0 0 0 0 0 0 effects 0 0 0 0 0 0 0 0 Oil sensitivity 2017. Frontiers in Ecology and the Environment. 15(3): 142-149.
Literature Synthesis Critically Critical Diet Matrix Food web importance sensitive for 1 0 1 0 1 1 0 1 species resilience 0 0 0 0 0 1 1 1 Ecological 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 1 Network 0 0 0 0 0 1 0 0 Analysis 0 1 0 0 0 0 0 0 Few indirect 0 1 0 0 0 0 0 0 effects 0 0 0 0 0 0 0 0 Oil Sensitivity Data Oil sensitivity Taxa Oil Sensitivity 2017. Frontiers in Ecology and the Environment. 15(3): 142-149.
52 nodes 376 links
Phytoplankton
Spartina alterniflora
Omnivorous snails Littoraria irrorata
Piscivorous fish
Oil Sensitivity No data (13) 0: none (16) 1: weak (10) 2: strong (12)
Food web importance Critically Critical sensitive for species resilience Few indirect effects Oil sensitivity 2017. Frontiers in Ecology and the Environment. 15(3): 142-149.
2017. Frontiers in Ecology and the Environment. 15(3): 142-149.
Food Web Resilience to Oil • Biomarker approach to food web effects • Bulk Stable Isotopes • Fatty Acids • Compound specific isotopes
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