Document Type

Thesis

Publication details

Owler, R 2012, 'Fine scale biodiversity, seasonal change and natural and anthropogenic influences at Lennox Head 'Bream Hole', within Cape Byron Marine Park, Northern New South Wales, Australia', MSc thesis, Southern Cross University, Lismore, NSW.

Copyright R Owler 2012

Abstract

The Lennox Head "Bream Hole" is a diverse and unique coastal system located in northern New South Wales at the southernmost section of the Cape Byron Marine , Park, which was declared on the 1st of November 2002. The study area supports a variety of different habitats including boulder fields that comprise of various sized boulders, patches of sand and sand grit, and a shallow lagoon. Prior to this study more than 180 different marine species were recorded in this area.

The Lennox Head "Bream Hole" has been zoned by NSW Marine Parks under three high protection categories - sanctuary zone, habitat protection zone, and special purpose zone. Until now only rapid assessment surveys of this area have been done. This study provides the first detailed study into the biodiversity, disturbances and water quality of the area and how these change over time.

Surveys for this study were done at five sites at the "Bream Hole" during four periods between February 2005 and February 2006. Data were recorded from six replicate quadrats at each site during each survey period. During this study a total of 142 different species of algae (39 species) and invertebrates (102 species) were recorded. Some species, such as the polychaete worm Branchiomma sp., had not previously been recorded at this location. In addition, 12 other taxa (10 invertebrate and 2 algal taxa) were identified to family level.

A diverse algal assemblage was present at the Lennox Head "Bream Hole" and this included 39 identified species plus two other taxa identified to family level. A complex turf algal assemblage was found at all sites, which contained a variety of microscopic and diminutive algae, and cyanobacteria. A seagrass species was also recorded at some sites. Algal cover, including the turf assemblage and seagrass cover, was greater at the two offshore sites (Sites 3 and 4) compared with the other three sites. Apart from the 'Turf' category, the most abundant algal species included Corallina sp., Jania sp., Sargassum sp., and Ulva australis.

The Class Gastropoda was found to have the most abundant number of individuals. The gastropod Austrocochlea porcata was the most abundant species in this class and a total of 6,006 individuals of this species were recorded throughout this study. The Class Bivalvia was also a dominant group with 3,884 individuals from this class recorded. Comparison of the seasonal data showed that for all survey periods Site 1 had the greatest number of individuals of the seven most abundant gastropod spec1es with 4,528 individuals counted, compared to Site 4 which only had 81 individuals recorded throughout the four survey periods. The May 2005 survey period had the most individuals (2,939) recorded, from the seven most abundant gastropods found at the study area.

Water temperatures varied between the inshore areas of the reef to the offshore areas during low tides and ranged from 21oC to 32oC throughout the study period. Water quality sampling, and sediment sampling, showed potential contamination from urban run-off during three storm events in 2005. Copper, aluminium, silver and zinc were slightly elevated in the storm water samples and were above the ANZECC & ARMCANZ (2000) trigger values. Copper, nickel and mercury were the main contaminants that were elevated in the sediment samples and were found to be above the ANZECC & ARMCANZ (2000) ISQG-Iow trigger values.

The results of this study provide quantitative baseline data on biodiversity and water quality at the Lennox Head "Bream Hole". Future studies are needed to monitor potential changes in the ecology of this area, to increase understanding of biodiversity including fish diversity, and to ensure that management of stormwater occurs to prevent environmentally significant contamination of the area that may decrease the biodiversity or threaten human health.