This project will improve our understanding of how seagrasses are affected by dredging activities, and will apply that understanding to better prediction of impacts and management of dredging. A combination of laboratory and field experiments and field surveys will determine the levels of dredging-related pressures (or 'thresholds') that produce the earliest observable effects, sub-lethal effects and lethal effects on two species of seagrasses considered most ecologically important in the NW. The research will also determine the capacity of those seagrasses to recover from dredgingwrelated stress. The research will focus on two of the most significant stresses produced by dredging:
- the reduction in light availability to plants; and
- the smothering of seagrass and algae as suspended sediments settle.
Objectives:
Project 5.1 - Reviews of existing information and identification of key species:
Review 1: Review the current state of knowledge regarding the effects of dredging-related 'pressure' on primary producers (seagrasses)
Review 2: Identify which primary producers (e.g. ephemerals/annuals/perennials) or different functional groups, that collectively cover the bio-geographic range of key primary producers in WA, are most appropriate for the focus of subsequent research into thresholds and indicators of response to dredging related pressures;
Project 5.2 - Natural processes in Seagrass ecosystems
Field Study 1: to characterize the genetic variability within populations of seagrasses to understand whether typical patches of meadow are genetically uniform or have multiple clones
Field Study 2: to determine whether recovery following disturbance is by sexual or asexual means and the relative importance of each
*Project 5.3 -
(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.