Suspended Algal Dynamics Across a Seagrass Meadow Landscape 150 views

Seagrasses are important foundation species in coastal ecosystems that facilitate primary production of themselves and macro-/microalgae and, through their water-baffling physical structure, encourage the accumulation of algal material in the system. However, the effect that seagrass meadows have on the vertical distribution of phytoplankton and suspended algal material and how that distribution changes seasonally and throughout the meadow landscape is largely unknown. To resolve this gap, I quantified suspended algal material in the water column across a seagrass meadow landscape in a temperate coastal lagoon. I collected samples stratified by depth at heights of 1, 5, 15, and 45 cm above the bottom at sites from which I calculated chlorophyll a and pheophytin concentrations. These sites were host to varying seagrass densities and differed in their distances from the meadow edge. I found that chlorophyll a concentrations were significantly higher in the bottom 1 cm of seagrass meadows than at other depths in the water column or at sites outside of the meadow. There was also a strong seasonal signal, with these concentrations most pronounced in late summer. This suggests a seasonal control of suspended algae concentration in the water column not reported in the literature. I found no significant relationship between chlorophyll a concentrations and seagrass density or distance from the meadow edge. Concentrations were instead dominated by the influence of habitat driven by seagrass presence/absence. These findings reveal spatial and temporal variation in suspended algal concentrations that likely exert controls on the secondary productivity of the diverse community of suspension feeding animals and adjacent bivalve aquaculture associated with this foundation species.

BS (Bachelor of Science)

seagrass; suspended algae; phytoplankton

English

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2022-05-10