Baseline Biodiversity Survey of the Cod Grounds Commonwealth Marine Reserve

June 15, 2010 by  

In May 2009, a team of RLS divers undertook special baseline reef surveys of the Cod Grounds Commonwealth Marine Reserve, off Laurieton on the NSW central coast. The Commonwealth Government commissioned a report of these surveys, which is available at the following link:

The report outlines results of the RLS surveys of reef habitat using standard RLS underwater visual census protocols on 24 transects in depths between 25 and 42 metres, at 11 sites inside and outside the CGCMR.
The fish fauna of the reserve and nearby reference sites was generally similar in composition
to inshore reefs of the area, but with a very high overall biomass. An average of 15.7 fish species was recorded per 50 m transect, with mado (Atypichthys strigatus), silver sweep (Scorpis lineolata) and one-spot pullers (Chromis hypsilepis) the most abundant. Average fish biomass (over all sites) was 272.4 kg per 500 m2, and higher carnivores and planktivores were the dominant trophic groups. Four grey nurse sharks were recorded on transects, and a further 18 counted at the base of the main pinnacles (site 8CG).
The mobile macroinvertebrate fauna was dominated by echinoderms and molluscs, with the spiny sea urchin (Centrostephanus rodgersii), orange feather star (Cenolia trichoptera), eastern slate-pencil urchin (Phyllacanthus parvispinus) and the mollusc Astralium tentoriformis most important by abundance and frequency of occurrence. Very clear depth-related patterns were evident in the macroinvertebrate fauna, largely related to which urchin species was dominant. Centrostephanus rodgersii dominated transects between 25 and 28 m, P. parvispinus dominated transects between 29 and 32 m and Prionocidaris callista were most abundant on transects deeper than 32 m.

The sessile community was characterised by either a high cover of crustose coralline algae or a diverse sessile invertebrate assemblage and a general lack of large macroalgae. Distinct differences were also noticed in the sessile community between transects at different depths. Transects less than 29 m had very low sessile invertebrate cover and low taxonomic richness, whilst transects deeper than 29 m had relatively lower cover of crustose coralline algae and higher richness and cover of sponges, ascidians and corals.


There is a complete list of acknowldgements in the report, but RLS would particularly like to thank the participating skilled volunteer divers; David Arthur, Bill Barker, Michele Crighton, Andrew Green, and Stephen Green, plus Peter Huettner (SCUBA Haven – see, Simon Talbot, Liz Oh and Alan Jordan.

Please click on the link to read the full report, including details of sites, methods and more results including threatened and exploited species, and community types and relationships between taxonomic groups.

Below is some beautiful footage of Grey Nurse Sharks taken over two days at the Cod Grounds by one of our volunteers, Martin Mueller. Thank you for sharing your video with us Martin.

Please take a look!


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