WAMSI 2 - Dredging Node - Project 5.5.1 - Defining thresholds and indicators of primary producers - Seagrass pressure-response relationships - Experiment 1

Objectives of Project 5.5 are to: (1) determining the pressure:response relationships that relate the effects of dredging-generated sediments on tropical primary producers, (2) examine the pathways, rates and timeframes of recovery from impacts and; (3) identify and examine the effects of key environmental variables on the pressure:response relationships and recovery.

Specifically Experiment 1 will be studying "Effect of different intensity, duration & timing of light reductions on seagrasses (Laboratory)"

Measurements included: Absorbancy Factors Biomass - Above ground mass (g DW per pot), Below ground mass (g DW per pot), Total plant mass (g DW per pot) Carbohydrates (%DW) and Starch (%DW) Growth & Morphology - leaf area (cm2), shoot density (per pot), Shoot production rate (shoots d-1) Nutrient & isotope data - Leaf ‰ 15 Nitrogen, Leaf ‰ 13 Carbon, Leaf Nitrogen (% DW) Leaf Carbon (% DW) Leaf Carbon to Nitrogen ratio (g g-1) Photosynthesis - Electron transport rate (um photons m-2 s-1), Alpha (um photons m-2 s-1), Half-saturating irradiance (um photons m-2 s-1) Pot Biomass - Pot mass (mass of all plants in a pot, g DW per pot)

Species studied included - Cymodocea serrulata and Halodule uninervis