Effects of sediment nutrients on seagrasses: Literature review and mesocosm experiment
A review of the literature shows that seagrass growth, abundance and morphology are strongly linked to available nutrient resources. In north temperate climates and in habitats with terrigenous sediments, nitrogen limitation occurs in both intertidal and subtidal beds. Typically, seagrasses growing in terrigenous sediments have ample phosphorus but lack nitrogen, and the plants' chemical composition is depleted in nitrogen. However, seagrasses occurring in tropical environments and carbonate sediments appear to experience phosphorus limitation due to binding of phosphate in the sediments. Thus, it is the sediment geochemistry in seagrass beds that is important in determining the limiting nutrient to seagrass growth.
Examination of the literature indicates that field research on seagrass relationships involves too many interactive factors to be able to say certainly that any one plant characteristics is caused by any one environmental factor. Using mesocosms (partially enclosed outdoor experimental set-ups) one environmental factor can be changed between the treatment tank and the control. Therefore, we can determine experimentally that a plant characteristic is affected by a particular altered environmental factor. Experimental mesocosms used to grow eelgrass, Zostera marina L., in substrata of varied nitrogen composition showed the dramatic effect of insufficient nitrogen on eelgrass growth, abundance and leaf morphology. Additionally, eelgrass leaf tissue from low ammonium sand substratum is significantly depleted in nitrogen, demonstrating the supposition that nitrogen is limiting in terrigenous environments.
Digital Object Identifier (DOI)
Short, F.T. 1987. Effects of sediment nutrients on seagrasses: Literature review and mesocosm experiment. Aquatic Botany 27:41-57.