The effects of boat propeller scarring intensity on nekton abundance in subtropical seagrass meadows
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Seagrasses play a critical role in the function and structure of coastal ecosystems, and they are an important habitat for a variety of marine organisms. Damage to seagrass beds caused by boat propeller scarring is significant in many areas. This study was designed to assess the impact of varying scarring intensities on nekton density. We selected ten replicate (10 m×25 m quadrats) sites representing four distinct scarring intensities: reference (0%), low (5% or less), moderate (5–15%), and severe (>15%). Sites were sampled in 2003–2004 for nekton during four seasons (summer, fall, winter, and spring) using epibenthic sleds. There were eight taxa numerically dominant in all seasons and an additional four seasonally dominant species. We were unable to detect a significant effect of propeller scarring on nekton density at any scarring level. Additionally, regression analysis indicated no relationship between scarring intensity and nekton density. These results suggest that propeller scarring intensities of up to ca. 27% may not impact nekton densities. However, seagrass loss, higher scarring intensity, and scale may play a critical role in determining the impact of propeller scarring on nekton.
KeywordsBlue Crab Submerge Aquatic Vegetation Seagrass Meadow Total Catch Grass Shrimp
We would like to thank the Members of the Fisheries Ecology Lab at Texas A&M University-Corpus Christi for their help on this project. Special thanks to Brooke Stanford, Ryan Fikes, Megan Reese, Amanda Bushon, and Annette Cardona for their hours of assistance in the field and laboratory, and to Steve Moore for producing Fig. 1. We gratefully acknowledge the comments and input by Chris Onuf. We would like to thank Ken Dunton of UTMSI and Richard Watson for flights over the study area. We would also like to thank anonymous reviewers for comments that greatly improved the earlier drafts of the manuscript.
- Beck MW, Heck KL, Able KW, Childers DL, Eggleston DB, Gillanders BM, Halpern B, Hays CG, Hoshino K, Minello TJ, Orth RJ, Sheridan PF, Weinstein MP (2001) The identification, conservation, and management of estuarine and marine nurseries for fish and invertebrates. BioScience 5:633–641CrossRefGoogle Scholar
- Britton JC, Morton B (1997) Shore ecology of the Gulf of Mexico, 3rd edn. University of Texas Press, AustinGoogle Scholar
- Dunton KH, Schonberg SS (2002) Assessment of propeller scarring in seagrass beds of the south Texas coast. J Coast Res 37:100–110Google Scholar
- Eleuterius LN (1987) Seagrass ecology along the coasts of Alabama, Louisiana, and Mississippi. In: Durako MJ, Phillips RC, Lewis RR (eds) Proceedings of the symposium on subtropical–tropical seagrasses of the Southeastern United States. Florida Marine Research Publication No. 42. Florida Department of Natural Resources, St. PetersburgGoogle Scholar
- Haila Y (2002) A conceptual genealogy of fragmentation research: from island biogeography to landscape ecology. Ecol Appl 12:321–334Google Scholar
- Lipton DW, Wellman KF, Shiefer IC, Weiher RF (1995) Economic valuation of natural resources—a handbook for coastal resource policymakers. NOAA Coastal Ocean Program Decision Analysis Series No. 5. NOAA Coastal Ocean Office, Silver SpringGoogle Scholar
- Minello TJ (1999) Nekton densities in shallow estuarine habitats of Texas and Louisiana and the identification of essential fish habitat. In: Benaka LR (eds) Fish habitat: essential fish habitat, and rehabilitation. American Fisheries Society, BethesdaGoogle Scholar
- Rozas LP, Minello TJ (1998) Nekton use of salt marsh, seagrass, and nonvegetated habitats in a south Texas (USA) estuary. Bull Mar Sci 63:481–501Google Scholar
- Sargent FJ, Leary TJ, Crewz D, Jruer CR (1995) Scarring of Florida’s seagrasses: assessment and management options. Technical Report TR-1. Florida Marine Research Institute, St. PetersburgGoogle Scholar
- SCPT (Seagrass Conservation Plan for Texas) (1999) Texas Parks and Wildlife, AustinGoogle Scholar