Abbot Point
The map below shows the historical extent of seagrass presence within our monitoring areas over the past ten years. The Abbot Point program has recently transitioned to a three-year cycle, completing a large survey of inshore/coastal and offshore areas every three years and smaller surveys in the intervening years.
Like most plants, seagrass responds to changes in its natural environment. So we also keep track of environmental influencers, such as light and temperature that may impact the distribution and condition of seagrass growing in our monitoring areas.
Many environmental influencers and events can impact the marine ecosystem. Major weather events that are particularly relevant in North Queensland are cyclones.
Cyclones typically generate extreme energy environments, with large waves and intense winds, both of which can have a strong physical impact on seagrass and their seed banks within the sediments such as burial, scouring, or direct removal of plants or seeds. Secondary impacts caused by associated high rainfall—such as changes in salinity, turbidity and nutrient levels during or leading up to the growing season—may also affect the seagrass.
Surveying of Abbot Point inshore seagrasses is focused on key dominant meadows, however for the purposes of the below graph comparisons and determining a percentage cover, the ‘inshore’ survey boundary area has been set at the mean sea level elevation of five metres. Further detail on the methods for monitoring can be found in these reports.
Environmental influencers -
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Higher water temperatures can make it difficult for seagrass to grow. A prolonged period of time of high water temperatures during the growing season, as well as an above-average water temperature for the year, can indicate pressure on coastal seagrass condition.
Water temperature over 10 years -
Solar radiation is a way of measuring the intensity of the sun as it falls on the water surface. High solar radiation may offer benefit to seagrasses by providing more energy for photosynthesis. However, when this is coupled with extended periods of high water temperature or extended periods of daytime exposure to air at low tide, we are, likely to see seagrass come under increased pressure (see below for density charts).
Solar radiation over 10 years -
As seagrasses need light to survive, they are sensitive to any pressures that may reduce the light available to them. High rainfall can lead to increased runoff from the land, turbid water flows into coastal environments and local coastal re-suspension that result in reduced levels of light reaching the ocean floor making it difficult for seagrasses to survive. In extreme cases high rainfall and flooding can also reduce the salinity of the water which may also cause stress to seagrasses.
Rainfall over 10 years
Seagrass extent
The chart to the right shows annual seagrass extent as a percentage of our total inshore survey area. These communities are generally dominated by Halophila ovalis, Zostera muelleri and Halodule uninervis.
Being in proximity to the flood plain discharge point of the Don River system, inshore seagrass communities within the Abbot Point region are particularly susceptible to high rainfall and flood plumes, as well as high temperatures and high wave and wind activity associated with cyclones.
Cyclones can present quite differently, with wind speed, trajectory and volume of associated rainfall all playing a key role in the potential impact on seagrasses. Tropical Cyclone (TC) Yasi in 2011 and TC Debbie in 2017 did not differ significantly in strength, however, associated rainfall, and resultant Don River discharge was much lower with TC Debbie. There was a marked difference in seagrass community area recorded in the years following each of these events.
Seagrass density
Seagrass density can be an important indicator of the health of a seagrass community. Denser seagrass communities can provide more complex habitat structure and protection for animals that use them as nursery grounds, and may also provide more food for turtles, dugongs and other marine animals.
In our monitoring areas, density is a representation of the above ground biomass of seagrass within each monitoring area.
As noted above, proximity to the Don River system discharge means that these seagrasses are particularly susceptible to high rainfall and flood plume events.
High levels of solar radiation and tidal exposure may also align with reductions in seagrass density due to photosynthetic stress from high temperatures and possible leaf burning.
While seagrass density is shown to be maintained in the moderate to high categories in the Abbot Point area, the variation between the years is primarily a product of changes in species composition from more persistent, larger stable species to smaller colonising species.
You can see more analysis on the data in these reports. You can also download the data used to create this chart.
Seagrass growth
The chart to the right shows data only from the years when the larger survey of deep water, offshore seagrass has been conducted. It shows seagrass extent as a percentage of our total offshore survey area.
The deepwater seagrasses offshore from Abbot Point are dominated by the species Halophila decipiens, H. ovalis, H. spinulosa and Halodule uninervis. These species, especially the Halophila’s, are known for their capacity to rapidly recover from disturbance through regeneration from fragments or seedbanks.
Apart from the years following TC Yasi, coverage has been in the order of 35-40 percent for each survey year.
Seagrass density
Seagrass density can be an important indicator of the health of a seagrass community. Denser seagrass communities can provide more complex habitat structure and protection for animals that use them as nursery grounds, and may also provide more food for turtles, dugongs and other marine animals.
In our monitoring areas, density is a representation of above ground the biomass of seagrass within each monitoring area.
The density of Abbot Point offshore seagrass is also driven by the species that make up the meadow in a particular year. For example, when H. spinulosa is the dominant species present in the meadow, we often see the density of the meadow being higher as this species is larger than H. decipiens.
You can see more analysis on the data in these reports. You can also download the data used to create this chart.
About the data
All data presented on this page has been compiled using data collected by James Cook University on behalf of North Queensland Bulk Ports. Every effort has been made to ensure its accuracy; however, errors can occur. If you notice anything that looks incorrect, please feel free to contact us to let us know. We will always do our best to rectify any errors as soon as we are aware of them.
Seagrass surveys are conducted during every growing season and we aim to upload new seagrass data for the prior year by the second quarter of each subsequent calendar year.