This thesis examines the relationships between human use and biological changes in the rocky intertidal zone of the Bunurong Marine Park, Victoria between January 1990 and June 1991. The key areas of activities were to i) describe the types and patterns of human activities on the reef, ii) assess the impact and recovery of reef biota to these activities with particular focus on Hormosira banksii, the dominant algal community and iii) determine the natural fluctuations in reef communities to provide a baseline to detect future changes in response to protection. Surveys of human activities between January 1990 and April 1991 found walking to be the most common activity. Levels of human use were greatest during school holidays followed by weekends and were lowest during term weekdays. During school holidays use varied with the time of day and use on term weekend depended on weather. The impact of collecting intertidal gastropods and trampling were investigated. There was no relationship between the observed patterns of human use and variations in the size distributions of collected and non-collected intertidal gastropods. Experimental trampling showed that the dominant alga on these reefs, Hormosira banksii, was severely affected by trampling. The cover of Hormosira was reduced by trampling and the decrease in cover depended on the level of trampling. No significant effects of trampling were detected for any other species. Trampled beds of Hormosirra banksii took well over a year to recover to the same level as adjacent mats. Algal monitoring showed that the cover of Hormosira was stable over time, except for a large decrease due to desiccation in summer. These findings are discussed in relation to the management of the Bunurong Marine National Park.

The abundance and size of individuals of 10 gastropod species were measured in rocky intertidal reefs in 10 Marine Protected Areas (Marine National Parks and Marine Sanctuaries) in Victoria, Australia. Similar surveys were conducted at 8 comparable sites outside these parks. The study species consist of broadcast spawners (Cellana tramoserica, Turbo undulatus, Austrocochlea constricta, Patelloida alticostata) and egg laying species (Nerita atramentosa, Bembicium nanum, Cominella lineolata, Dicathais orbita, Lepsiella vinosa, Siphonaria diemenensis) with different larval dispersal potentials.

An experiment was conducted to compare the effects of the introduced bryozoan, Bugula neritina, and the native bryozoan, Bugula dentata, on sessile invertebrate assemblages. Individuals of both species were collected from Workshops Jetty and Altona Pier prior to the experiment and transported back to the laboratory. Two colonies of either B. neritina or B. dentata were attached to each plate using sponges that expanded when wet. The plates were then transported to Workshops Jetty and attached to plates and left for 12 days. At the conclusion of the experiment plates were collected and abundances of species on the plates were counted and identified.

Exclusions were attached to artificial substrata to investigate the relative effects of predation on the development of epifaunal communities at Portsea. Exclusions were black plastic mesh cages enclosing panels that were attached to rigs under the Portsea Pier. Bare control panels and cage controls where included in the experimental design. Cage controls had the bottom and half of the roof on the cage removed. There were 2 replicate panels of each treatment that were immersed for 2, 4 or 7 months and there were 6 runs of the experiment from October 1975 to November 1977. At the conclusion of each run of the experiment the panels were fixed in 4% formalin-seawater solution. In the laboratory, the number of individuals and percent cover of colonial species on each panel were recorded. Surveys identified that grazing fish were the most abundant predator of the epifaunal community at Portsea during the experiment. Predation significantly affected the pattern of establishment of the epifaunal community. There were fewer ascidian recruits and more diverse communities on bare control panels because fish predation prevented monopolisation of space by dominant ascidian competitors. On caged panels were there was no fish grazing, the survival of colonial ascidians was greater and the panels were dominated by arborescent bryozoans and ascidians.

Three removal experiments were conducted to test the effects of the introduced species, Bugula neritina, Ascidiella aspersa and Botryllus schlosseri on sessile invertebrate assemblages. Each experiment was run for approximately 2 months between 28th November 2004 and 13th February 2004. These experiments involved removing the introduced species from plates and then comparing these assemblages to those on disturbed control and control plates, where the introduced species had not been removed. The introduced species were removed by scraping them and surrounding species from the surface in 1/8 or 1/4 cm2 areas or by peeling individuals off with forceps. All individuals on the plates were counted and identified at the completion of the experiments.

This study examined the impacts of 2 of the most common epibenthic suspension feeders, Sabella spallanzanii and Styela clava, in Port Phillip Bay, by transplanting individuals from the surrounding habitat into 2 x 2m experimental plots. Densities in the plots represented naturally occurring densities, ranging from 0.5 to 10 individuals per m-2 for Sabella and from 0.5 to 5 individuals per m-2 for Styela. At the completion of the 10 week experimental period the numbers of alive and dead Sabella and Styela in each plot were counted. The infauna in each plot was sampled by inserting 2 metal cylinders to a depth of 15cm into each plot. The sediment within each cylinder was vacuumed to a depth of 10cm into a 1mm mesh bag using a diver-operated, water-driven suction device. The total area in each plot that was sampled was 0.2m2 (cylinder diameter = 35.5cm). Macrofauna were counted and identified in the laboratory to the lowest possible taxon, which was mostly Family. There were significant effects on individual taxa at Sabella and Styela densities greater than 1-2 individuals per m-2, which are densities greater than those typically recorded in Port Phillip Bay. There was a significant negative relationship between Sabella density and the abundance of lumbrinerid polychaetes and gammarid amphipods, and between Styela density and the abundance of lumbrinerids, tanaids, crustaceans as a group, and the bivalve Laternula rostrata.

To examine ecological interactions between fish and invertebrates, to aid in the understanding of potential impact through human disturbance.

Artificial substrata were used to investigate the patterns of establishment and change in the structure of a subtidal, marine epifaunal community at Portsea, Victoria from October 1975 to November 1979. Sessile invertebrate species and mobile species that significantly affected the distribution and abundance of the sessile species were the focus of the study. Experiments examining variability in recruitment and community development, species competitive ability, and the effects of predation on the epifaunal community at Portsea are outlined in the related records.

Wave action was measured on 10 sampling occasions from April to October 1987 in the high and low intertidal zones on a rocky shore in Western Port Bay, Victoria. Forty dynamometers (20 in each zone) were deployed on each sampling occasion and left out for 2 tidal cycles (approx. 24 hours). The maximum force that was exerted on the dynamometer within this period was recorded on a spring scale. The force exerted by the waves was directly proportional to water velocity.