Winter biomass and nutrient values of three seagrass species as potential foods for redheads (Aythya americana eyton) in Chandeleur Sound, Louisiana

We studied biomass and macronutrient content ofHalodule wrightii (shoalgrass) throughout the winter and ofThalassia testudinum (turtlegrass) andSyringodium filiforme (manateegrass) in January in Chandeleur Sound, LouisianaHalodule, the primary fcod of wintering redheads, had the lowest biomass of the three species on the study area in mid-winter. Macronutrient content ofHalodule did not change during the winter, but aboveground and belowground biomass showed a 90 and 49% (P<0.0001) decrease from October to March. Macronutrient content seems not to be the basis for selection by redheads ofHalodule over the other two seagrass species or of selection of belowground over aboveground parts.