Palabras clave
Thalassia testudinum
patch abandonment
Chelonia mydas
herbivory
grazing behavior
giving up density (GUD)
seagrass
Thalassia testudinum
patch abandonment
Chelonia mydas
herbivory
grazing behavior
giving up density (GUD)
Cómo citar
Resumen
Green sea turtles, Chelonia mydas, are grazers influencing the distribution of seagrass within shallow coastal ecosystems, yet the drivers behind C. mydas patch use within seagrass beds are largely unknown. Current theories center on food quality (nutrient content) as the plant responds to grazing disturbances; however, no study has monitored these parameters in a natural setting without grazer manipulation. To determine the morphological and physiological responses potentially influencing seagrass recovery from grazing disturbances, seagrasses were monitored for one year under three different grazing scenarios (turtle grazed, fish grazed and ungrazed) in a tropical ecosystem in Akumal Bay, Quintana Roo, Mexico. Significantly less soluble carbohydrates and increased nitrogen and phosphorus content in Thalassia testudinum were indicative of the stresses placed on seagrasses during herbivory. To determine if these physiological responses were the drivers of the heterogeneous grazing behavior by C. mydas recorded in Akumal Bay, patches were mapped and monitored over a six-month interval. The abandoned patches had the lowest standing crop rather than leaf nutrient or rhizome soluble carbohydrate content. This suggests a modified Giving Up Density (GUD) behavior: the critical threshold where cost of continued grazing does not provide minimum nutrients, therefore, new patches must be utilized, explains resource abandonment and mechanism behind C. mydas grazing. This study is the first to apply GUD theory, often applied in terrestrial literature, to explain marine herbivore grazing behavior.
Elizabeth A. Lacey1*, Ligia Collado-Vides2, James W. Fourqurean2
1School of Natural Sciences and Mathematics, The Richard Stockton College of New Jersey, Galloway, New Jersey 08205 USA; elizabeth.lacey@stockton.edu
2Department of Biological Sciences, Florida International University, Miami, Florida 33199 USA; colladol@fiu.edu, jim.fourqurean@fiu.edu
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Derechos de autor 2014 Revista de Biología Tropical