Influences of Season and Water Depth on the Clonal Biology of the Seagrass Thalassia testudinum

Tomasko, D; Dawes, C

Ramet density, leaf relative growth rates, leaf chlorophyll levels, and proximate constituent levels were determined on three dates in 1988 at three water depths for a Thalassia testudinum Banks ex Konig Meadow in lower Tampa Bay, Florida, USA. Density varied seasonally in patterns unique to each depth. Leaf relative growth rates indicated a unimodal, rather than bimodal, growth pattern at this site. Leaf chlorophyll levels reflected both depth-related and seasonal influences with levels at all depths increasing at times of high light attenuation. Based on results from leaf relative growth rates and proximate constituent levels, the degree of ramet interdependence appears to vary with sampling date and water depth. The degree of ramet interdependence appears to be maximal in times of genet expansion (June and August) and minimal in times of energy storage (November). Interdependence of ramets varies spatially as well; ramets are maximally integrated in shallow regions (on dates when genet proliferation occurs), and minimally integrated at deep edges. Depth-related differences on ramet integration are probably due to the spatial heterogenity of the primary resource limitation varying with water depth, and to depth-related differences in ramet population dynamics. Patterns of ramet physiological integration in T. testudinum are similar to the patterns reported for terrestrial clonal plants.

Influences of Season and Water Depth on the Clonal Biology of the Seagrass Thalassia testudinum

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