Port of Hay Point & Keswick Island seagrass & benthic habitat: baseline survey: 2014
Other Publication ResearchOnline@JCUAbstract
This report presents the results of a survey of seagrass, algae and habitat forming benthic macroinvertebrates in the Hay Point and Keswick Island group region conducted in October/November 2014. The survey provides an updated baseline (last assessed in 2010) on habitat forming benthic communities including seagrass in the vicinity of the port of Hay Point and at a reference site in the Southern Whitsundays and provides the basis for an ongoing long term monitoring strategy. • In 2014 seagrass distribution was the largest recorded since the initial baseline assessments conducted in 2004. Seagrass was present at 16% of survey sites and was found to a depth of 19.9m (depth below mean sea level (dbMSL)) in the Hay Point region and 29.7m dbMSL adjacent to Keswick Island. • Six species of seagrass were recorded. Halophila decipiens dominated offshore meadows in the Hay Point region while Halophila tricostata dominated the Keswick Island seagrass meadows. The 2014 survey was the first recorded occurrence of Zostera muelleri in the coastal meadows of Hay Point and Halophila ovalis in the offshore meadows. • There have been four previous mapping surveys conducted of the Hay Point seagrass habitat (2004, 2005, 2010 & 2011). Overall the locations and species composition of coastal and offshore seagrass meadows in the Hay Point area have been similar between surveys. The 2014 and 2004 surveys had the largest extent of seagrass. • The benthic macro-invertebrate and algal communities within the survey area were typical of communities found in offshore and nearshore subtidal areas elsewhere in Queensland and similar to previous assessments at the site. • The dominant habitat feature within the survey area was open substrate with a low to medium density of benthic community life. There were no benthic macro-invertebrate communities that were classified as 'high density', however there were macro-algae communities classified as ‘high density’ in offshore and nearshore areas of Hay Point. • Medium and high density algae communities coincided with regions of medium density benthic macro-invertebrate communities, and tended to be concentrated around habitatforming 'live' and dead rock/rubble and reef. This association led to the observed pattern of higher biodiversity patches within the survey area. • There have been two previous surveys of benthic macro-invertebrates and macro-algae in the Hay Point area; 2004 and 2010. Moderate density benthic macro-invertebrate communities occurred across a greater area in 2004 and 2014 compared to 2010. • The density and distribution of macro-algae across surveys changed considerably. The distribution of macro-algae was highest in 2004 and lowest in 2010. The only functional group identified in 2010 was erect macrophytic algae. While 2014 was the only survey to record 'high density' areas of algae these areas were dominated by filamentous algae rather than the more structurally complex macro-algae groups. • Five offshore and two coastal areas in the Hay Point/Mackay region have been identified for a long-term seagrass monitoring program with an additional two reference areas in the Keswick Island group.
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15/11
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46
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James Cook University
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Cairns, QLD, Australia
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