The relationships between the standing stock of marine benthic microalgae and physical variables and nutrients in the water column and porewaters were explored by comparing a wave-exposed field location at Marmion Lagoon, Western Australia, to less disturbed benthic mesocosms. For field stations in Marmion Lagoon, multiple regressions of chlorophyll a concentrations against the PCA scores (PCA1, PCA2, PCA3) indicated chlorophyll a was only significantly negatively related to PCA1 scores, which itself was dominated by temperature, salinity, DO, NOx, SiO4 and SRP from the water column. Concentrations of chlorophyll a in surface sediments at field stations were significantly positively correlated to decreased temperature and salinity and negatively correlated to increased water column nutrients over the duration of the experiment. For mesocosms, chlorophyll a concentrations were not significantly related to any of the PC axes, indicating that shifts in temperature, salinity and nutrients in water column and porewaters were not responsible for the observed distribution of chlorophyll a in surface sediments. Benthic microalgae standing stock did not respond in similar ways in mesocosms and field stations to changes in nutrient status in the water column and surface sediments. There was a visible difference in the level of disturbance of surface sediments. In field stations, sand was resuspended and ripples developed on surface sediments in response to winter storm swells. In mesocosms, where disturbance of sediment was reduced, a surface layer of detritus and living benthic microalgae developed on the sediment surface and appeared to reduce the rate of nutrient efflux out of the sediment. (C) 1998 Elsevier Science BN. All rights reserved.
|Journal||Journal of Experimental Marine Biology and Ecology|
|Publication status||Published - 1998|