2015-11-10 - P&O Agenda - Item 7, Attach 2 - Assessment of Oyster Recruitment

2.3 Data Analysis
Differences in the total number of oyster recruits (Planostrea pestigris) were compared
between vertical and horizontal among sites using a 2 factor PERMANOVA (with site and
orientation as factors) (Anderson et al. 2008). Separate analyses were completed for
intertidal and subtidal habitats due to differences in the spatial location of some sites (i.e.
those in the Noosa River Estuary). The analyses were completed using untransformed data
converted to a Euclidean similarity matrix. Differences in the total number of recruits per site
and orientation were compared using pairwise comparisons.

Growth and Size-Frequency Distribution of Oysters

In the absence of a more detailed growth estimate, a rough linear growth rate was estimated
based on the average size of the oyster P. pestigris (pooled among all subtidal sites) after 2
months, 3 months and 5 months deployment. An average growth rate of approximately
4 mm (± 1.5 mm) per month was estimated assuming linear growth over the 5 months
deployment, which was used to define the size class estimates. The oyster recruits were
pooled among replicates at each site to examine variation in the size frequency distribution.
This was done only for the intertidal depth, as there was an insufficient number of recruits on
subtidal tiles to warrant any meaningful analysis. Oysters were sorted into ten, 4 mm size
classes, between 1 and 40 mm and the number of oysters in each size class was graphed
for each site.




Restoration of Noosa Estuary: An Assessment of Oyster Recruitment                                 7