Assessment of propeller and off-road vehicle scarring in seagrass beds and wind-tidal flats of the southwestern Gulf of Mexico
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Summer R. Martin
Abstract
We used aerial photography and GIS to establish a quantitative baseline of propeller and off-road vehicle (ORV) scarring in seagrass and wind-tidal flats of the upper Laguna Madre in the Padre Island National Seashore (Texas, USA). We also examined scar recovery through comparison of recent (2002, 2005) and historical (1967) aerial photographs of the study area. Scarring intensity was calculated using two different methods. In the first, polygons were visually drawn around groups of scars on digital images. Scarring intensity was estimated as light (<5%), moderate (5–20%), or severe (>20%), based on the total coverage of scars within each polygon (taking into account the length, width, and density of scars). We developed a more objective method that employed creation of vector grid cells and buffers that incorporated the localized ecological impact of scars. Results of spatial and temporal analysis revealed that the polygon approach greatly underestimated the magnitude of scarring. For example, in a single photograph, 7% of seagrass area was lightly scarred according to the polygon method; but light scarring increased to 51% according to grid analysis of the same image. Our results also indicated that propeller scars in Halodule wrightii beds appear to recover in less than three years and ORV tracks have persisted in the wind-tidal flats for at least 38 years. Our approach provides resource managers with procedures for a more objective and efficient assessment of physical disturbances to seagrass and wind-tidal flats caused by boats and ORVs.
©2008 by Walter de Gruyter Berlin New York
Articles in the same Issue
- Research articles
- Assessment of propeller and off-road vehicle scarring in seagrass beds and wind-tidal flats of the southwestern Gulf of Mexico
- Seasonal variation in a deep subtidal Zostera marina L. bed in southern Spain (western Mediterranean Sea)
- Short-term indicators of seagrass transplant stress in response to sediment bacterial community disruption
- Species composition and seasonal changes in macroalgal blooms in lagoons along the southeastern Gulf of California
- Growth and reproductive phenology of Pterocladiella capillacea (Rhodophyta: Gelidiales) from the southern Adriatic Sea
- Distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of Dictyota dichotoma (Dictyotales, Phaeophyceae)
- Chylocladia wynnei sp. nov. (Champiaceae, Rhodophyta) from the Mediterranean Sea
- Diplopsalopsis kisselevii sp. nov. (Dinophyceae) from the northwestern Sea of Japan
- Short communication
- Laurencia caduciramulosa (Ceramiales, Rhodophyta) from the Canary Islands, Spain: a new record for the eastern Atlantic Ocean
- Corrigendum
- Dictyota dolabellana sp. nov. (Dictyotaceae, Phaeophyceae) based on morphological and chemical data; Bot. Mar. 50 (2007): 288–293
- Meetings
Articles in the same Issue
- Research articles
- Assessment of propeller and off-road vehicle scarring in seagrass beds and wind-tidal flats of the southwestern Gulf of Mexico
- Seasonal variation in a deep subtidal Zostera marina L. bed in southern Spain (western Mediterranean Sea)
- Short-term indicators of seagrass transplant stress in response to sediment bacterial community disruption
- Species composition and seasonal changes in macroalgal blooms in lagoons along the southeastern Gulf of California
- Growth and reproductive phenology of Pterocladiella capillacea (Rhodophyta: Gelidiales) from the southern Adriatic Sea
- Distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of Dictyota dichotoma (Dictyotales, Phaeophyceae)
- Chylocladia wynnei sp. nov. (Champiaceae, Rhodophyta) from the Mediterranean Sea
- Diplopsalopsis kisselevii sp. nov. (Dinophyceae) from the northwestern Sea of Japan
- Short communication
- Laurencia caduciramulosa (Ceramiales, Rhodophyta) from the Canary Islands, Spain: a new record for the eastern Atlantic Ocean
- Corrigendum
- Dictyota dolabellana sp. nov. (Dictyotaceae, Phaeophyceae) based on morphological and chemical data; Bot. Mar. 50 (2007): 288–293
- Meetings
