Application 124771 - Ministry of Fisheries

MAY 2012 REPORT NO. 2134 | CAWTHRON INSTITUTE
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celidotus), sea stars (Coscinasterias muricata, Patiriella regularis and Astrostole
scabra), crustaceans (particularly crabs like the pillbox crab, Halicarcinus
innominatus; the half crab, Petrolisthes novaezelandiae; and the masking crab
Notomithrax minor), sea urchins, and other echinoderms (like the sea cucumber,
Stichopus mollis).
Despite having the greatest organic content in benthic sediments (Figure 4), Farm site
1 and its surrounding area had the highest diversity of epibiota, with abundant Steyla
clava (~41), finger sponges (Callyspongia spp.) and horse mussels (Atrina
zealandica, abundance estimated to be 0.52 m -2 ).
Consistent with the results of the sediment samples, a mud/silt substratum was the
most common substratum observed across reference farm and control sites (Figure 8
C- E). A shell/sand substratum was observed only at one control site (Con 1, Figure
8A) and at one farm site (Farm 1, Figure 8B). Horse mussels were most commonly
observed on substrata with a greater sand content, both beneath reference farms and
at control sites. They were most common in a small patch in one transect at Con 1,
where 45 were observed in a 20 m transect. An orange benthic diatom film was
common at reference farm and control sites, particularly on shallower silt/mud habitats
(Figure 8C and 8D).