PARENT SESSION
Contributed Oral Session 83: Human Impacts on Coastal Areas
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 520 A, Level 5, Palais des congrès de Montréal
Nutrients increase epiphyte loads: broad scale observations and an experimental assessment.
Elsdon, Travis *,1, Russell, Bayden1, Gillanders, Bronwyn1, Connell, Sean1, 1 University of Adelaide, Adelaide, South Australia, Australia
ABSTRACT- There is a global trend towards elevated nutrients in coastal waters, especially on human-dominated coasts. We assessed local (m′s) to regional scale (1000′s kms) relationships between the abundance of epiphytic algae on kelp (Ecklonia radiata) and nutrient concentrations across much of the temperate coasts of Australia, thus, assessing the spatial scales over which nutrients may affect benthic assemblages. We tested the hypotheses that (1) percentage cover of epiphytic algae would be greater in areas with higher water nutrient concentrations, and (2) that an experimental enhancement of nutrient concentrations on a nutrient limited coast, to match more nutrient rich locations, would cause an increase in percentage cover of epiphytic algae, which would match those in nutrient rich waters. Percentage cover of epiphytes was most extensive around one urban location that had the greatest concentration of coastal chlorophyll a. Experimental elevation of nutrient concentrations at a nutrient limited location caused an increase in percentage cover of epiphytes that was comparable to percentage covers observed around an urbanised location. This result was achieved despite our inability to match nutrient concentrations observed around urban locations (< 5 % of urbanised nutrient concentrations), suggesting that increases in nutrient concentrations may have disproportionately larger effects in nutrient limited waters.
Key words: scale, nutrients, algae, epiphyte