Data collected to determine settlement success of flat oyster larvae on nine different types of hard substrate.
These substrate types include granite, sandstone, flint, conventional concrete, concrete with natural adhesives (ECOncrete), galvanized steel, biodegradable plastic (BESE), mussel shell, and clay roof tile.
The experiments took place at two different locations in Ireland, i.e. in an oyster spatting pond (controlled conditions; New Quay) and near a wild population of oysters (natural environment; Tralee Bay).
The substrates were contained in polyethylene baskets (diameter 15cm, height 40cm) with a 2x2cm mesh size.
Weight and volume of the content in each basket was determined prior to deployment.
At both locations, the substrate baskets (n=5 per substrate type) were suspended 20-30cm below the water surface, approximately 30cm apart.
The sequence of the substrate baskets was randomly assigned.
After retrieval of the substrate baskets, the substrates in each basket were weighed, biofouling was removed, and if necessary, the substrate was cleaned using filtered seawater.
Then, the total number of oyster spat on the substrate was counted.
In order to assess the initial settlement preference, the total number of spat included both living and dead spat, which was recorded separately.
In order to compare the spat densities on the different substrate types, the three-dimensional surface area of the different substrates was estimated using a combination of double wax dipping and 3D scanning.
To determine which substrate collected the highest numbers of spat, the total numbers of spat were compared between the two locations and between different substrate types.
Spat density was taken as an indicator for settlement preference, calculated by dividing total spat by the available settlement surface in cm2.
Spat survival was calculated as the fraction of living spat out of the total spat counted after retrieval, and also compared between locations and substrate types.
For further information see manuscript
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