Year

2011

Degree Name

Bachelor of Marine Science (Honours)

ANZSRC / FoR Code

0502 ENVIRONMENTAL SCIENCE AND MANAGEMENT, 050202 Conservation and Biodiversity, 050206 Environmental Monitoring, 050211 Wildlife and Habitat Management

Department

School of Earth & Environmental Sciences

Abstract

Mangrove and saltmarsh communities are essential components of estuarine ecosystems on the NSW south coast. Globally, projected sea level rise under IPCC climate scenarios pose a significant threat to the survival of mangrove and saltmarsh ecosystems. The resilience of mangrove and saltmarsh to the impacts of sea-level rise is dependent upon the maintenance of their elevation with respect to rising water levels and their ability to migrate landwards and requires further analysis. An integrated vulnerability assessment of the mangrove and saltmarsh at Minnamurra River, NSW, was undertaken to assess the resilience of mangrove and saltmarsh to the impacts of sea-level rise and recommend future adaptation policy and management strategies to preserve these communities.

Comments

Mangrove and saltmarsh communities are essential components of estuarine ecosystems on the NSW south coast. Globally, projected sea level rise under IPCC climate scenarios pose a significant threat to the survival of mangrove and saltmarsh ecosystems. The resilience of mangrove and saltmarsh to the impacts of sea-level rise is dependent upon the maintenance of their elevation with respect to rising water levels and their ability to migrate landwards and requires further analysis. An integrated vulnerability assessment of the mangrove and saltmarsh at Minnamurra River, NSW, was undertaken to assess the resilience of mangrove and saltmarsh to the impacts of sea-level rise and recommend future adaptation policy and management strategies to preserve these communities.

Surface Elevation Tables (SET) and Marker Horizons (MH) were established within mangrove and saltmarsh in 2001 to establish the elevation and accretion dynamics and trends of the study site. Current surface elevation trajectories were much lower than average local sea-level rise over the study period and compared to longer-term local sealevel trends. Surface elevation appeared to be associated with fluctuations in groundwater levels and hence linked with El Niño and La Niña patterns. In accordance with models of sea-level rise impacts on mangrove and saltmarsh communities, photogrammetric mapping of the study site for the period 1938 to 2011 indicated mangrove encroachment of saltmarsh was evident and in recent years consolidation of mixed zones by mangroves.

A Digital Elevation Model (DEM) was constructed using LiDAR and high precision GPS data collected from the site. This was used as the basis for the creation of statistical and spatial models exploring the relationship between surface elevation dynamics, water level changes and mangrove encroachment of saltmarsh. These models projected wetland surface elevation and vegetation distributions in accordance with IPCC projections of sealevel rise. The models indicated that coastal wetlands at Minnamurra are highly vulnerable to future sea-level rise. Using the highest IPCC sea-level rise scenario, the models showed a significant loss of saltmarsh in the next 40 years and loss of mangrove communities by the end of the century. It is recommended that future adaptation policy and management focuses on groundwater regulation in the catchment and the introduction or extension of buffer zones.

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