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WAMSI 2 Dredging Science Node: Theme 5 Project 5.4 Recovery mechanisms

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WAMSI 2 Dredging Science Node: Theme 5 Project 5.4 Recovery mechanisms


The objective of Project 5.4 was to determine whether recovery of seagrass in the Pilbara following disturbance is by sexual (recruitment from seeds) or asexual (vegetative regrowth from rhizome extension) means, and the relative importance of each, thereby determining the capacity, timeframes and mechanisms of recovery from light and sediment depo... more


Biological Oceanography


15 Nov 2014


30 Jun 2015


Mat Vanderklift
Mat.Vanderklift@csiro.au

Primary producer response to dredging related pressures; Still Cameras - underwater; Western Australian Marine Science Institute


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Link to CSIRO - Oceans and Atmosphere IDC homepage

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Web address for organisation CSIRO Oceans & Atmosphere - Floreat

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At each of the two sites at Thevenard Island (21.5S, 115.0N: one at 2 m and the other at 6 m depth), 12 circular plots (diameter 75 cm) were completely cleared of all seagrass by hand. Six of the cleared plots were surrounded by a dark plastic border sunk into the sediment to a depth of 6 cm to prevent rhizome extension from surrounding meadow, and six cleared plots were left without a border to allow rhizome extension. Six uncleared plots were surrounded by a plastic border with gaps to create a procedural control (to verify whether the presence of the border itself influenced the ability of seagrass to grow within the plot), and six additional uncleared plots were marked as unmanipulated controls. The experiment was established on the 23rd and 24th of November 2014, and recovery was monitored at 10, 38, 45 and 98 days afterwards. Final measurements were to be taken in June 2015 at approximately 190 days from the establishment of the experiment, but in March 2015 Tropical Cyclone Olwyn (Category 3) passed within 40 km of Thevenard Island, and when the experiment was visited on 11 June 2015, none of the experimental apparatus (borders, tags, star pickets) remained at the 2-m ('shallow') site. The plots were intact at the 6-m ('deep') site, but visibility was extremely poor, and although photographs were taken they could not be analysed with confidence. On each monitoring date, photographs were taken of each plot. Divers also produced diagrams of any seagrass growth in cleared plots. Each photograph was analysed using TransectMeasure (® SEAGIS) software. A random array of 200 dots was placed over the image of the plot, and for each dot an operator (R. McCallum) identified the substrate immediate underneath as seagrass species, sediment, epibenthos or macroalgae under the dot. To further distinguish whether any regrowth was occurring from the edges of the plots (implying vegetative recovery) the dots were assigned into 'edge' (outer 20% of the plot) and 'centre' (inner 80% of the plot)


CSIRO, Edith Cowan University, Western Australian Science Institution; Mathew Vanderklift; Douglas Bearham; Mick Haywood; Paul Lavery; Roisin McCallum; James McLaughlin; Kathryn McMahon and Nick Mortimer


Creative Commons Attribution 4.0 International Licence


CSIRO (Australia), Western Australian Marine Science Institution (WAMSI) (Australia)


Vanderklift, Mat; Haywood, Mick; McLaughlin, James; Lavery, Paul; Bearham, Douglas; McMahon, Kathyrn; McCallum, Roisin; Mortimer, Nick (2016): WAMSI 2 Dredging Science Node: Theme 5 Project 5.4 Recovery mechanisms. v3. CSIRO. Data Collection. 102.100.100/39010


All Rights (including copyright) CSIRO 2016.


Access to this collection's metadata and/or files are restricted until 30 Nov 2017. Although the associated metadata is public, the files have not been approved for general release. Please phone or email the contact person for this collection to discuss access to the files.

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Location Details

21°23′60″ S


21°30′0″ S


115°5′60″ E


114°54′0″ E


WGS84


More about this Collection

Hiski Kippo


Senior Technical Officer


-6 m


0 m



Textual or tabular




eng


utf8


Oceans


About this Project

WAMSI-Dredg T5 Primary producer r


Defining thresholds and indicators of response by corals, seagrasses and filter-feeders to dredging-related pressures. See also: http://www.wamsi.org.au/dredging-science-node-0


Mat Vanderklift


Recovery Mechanisms


Understanding mechanisms of seagrass recovery following seabed disturbances.


Survey


Mat Vanderklift


Mick Haywood


James McLaughlin


Paul Lavery


Douglas Bearham


Kathyrn McMahon


Roisin McCallum


Nick Mortimer


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