Dive surveys of long spined sea urchin (Centrostephanus rodgersii) and barrens habitat, Tasmania

The spatial extent of the long spined sea urchin, Centrostephanus rodgersii, was estimated by divers using underwater visual census methods to survey rocky reef habitats at 13 regions along Tasmania's east coast (between Eddystone Point and Recherche Bay). Within each region 3 subsites were surveyed, and within each subsite 4 belt transects were surveyed. Divers recorded depth, percent substrata type, percent C. rodgersii barrens habitat; abundance of urchins (C. rodgersii and H. erythrogramma), rock lobster (J. edwardsii) and abalone (H. rubra). Divers also recorded algal cover (estimated), C. rodgersii barrens and substratum type using set categories (see below).

Larval transport of the introduced Northern Pacific Seastar (Asterias amurensis) in the Derwent Estuary, SE Tasmania

This study assessed the spatial and temporal (horizontal and vertical) distribution of Asterias amurensis larvae in the Derwent Estuary and adjacent Storm Bay, SE Tasmania. Horizontal transport and development was assessed by collecting plankton samples at 2 or 4 week intervals, from July to December 2001, at 4 sites in the Derwent Estuary and 6 sites in Storm Bay. The effects of light and salinity on vertical distribution of larvae was examined over a 24 hour tidal and diel cycle.

Reproductive potential of the long spined sea urchin Centrostephanus rodgersii in Tasmania

Recent poleward range expansion of the barrens-forming sea urchin Centrostephanus rodgersii (Diadematidae) from mainland Australia to Tasmania, has emphasized the need to understand the population dynamics of this ecologically important species in Tasmania. This work informs potential population dynamics of C. rodgersii in Tasmania by examination of its reproductive ecology. Reproductive periodicity (gonad index and propensity to spawn) was assessed bimonthly for 18 months at 4 sites in eastern Tasmania. Gamete viability was assessed by fertilization and early development trials. Temperature tolerance of Tasmanian C. rodgersii larvae was also assessed to determine whether this species has undergone an adaptive shift to the cooler Tasmanian environment. There was also no evidence for an adaptive shift in reproductive phenology. Reproductive phenology was assessed by determination of peak spawning period (gonad index analysis).

Understanding movement patterns of key reef species, with respect to determining appropriate spatial management regimes

Black Jew fish in the Northern Territory and Banded Morwong and Bastard Trumpeter in Tasmania have been tagged with acoustic tags and tracked using VR2's (presence/absence data) and VRAP (triangulated positional data) (Tas fish only).

Surveys of sea urchins (Centrostephanus rodgersii and Heliocidaris erythrogramma) and associated barrens habitat, Kent Group, Tasmania 1974, 1981

Quantitative surveys were undertaken at five sites in the Kent Group, north eastern Tasmania (Murray Pass, Winter Cove, Little Squally Cove,and southern end of Erith Island) by divers using underwater visual census methods to survey the reef habitat. Additional spot dive surveys were undertaken at northern side of East Cove, Garden Cove, Winter Cove, Squally Cove (Deal Island), northern and southern sides of West Cove (Erith Island) and north east and north west coasts of Dover Island. Divers recorded numbers of sea urchins (Centrostephanus rodgersii and Heliocidaris erythrogramma), as well as extent of urchin barrens, size of algal patches, and measured boundaries of macroalgal patches of Macrocystis angustifolia, Phyllospora comosa and Ecklonia radiata-fucoid communities. Spot dives detailed additional qualitative observations of C. rodgersii.

Range expansion of the sea urchin Centrostephanus rodgersii leads to loss of taxonomic diversity in a kelp bed habitat, eastern Tasmania

The long spined sea urchin Centrostephanus rodgersii (Diadematidae) has recently undergone poleward range expansion to eastern Tasmania (southeast Australia). This species is associated with barrens habitat which has been grazed free of macroalgae, and therefore has potentially important consequences for reef structure and biodiversity. This study used urchin removal experiments from barrens patches in eastern Tasmania to monitor the subsequent response of the macroalgae relative to unmanipulated barrens patches. In removal patches, there was a rapid proliferation of canopy-forming macroalgae (Ecklonia radiata and Phyllospora comosa), and within 24 months the algae community structure had converged with that of nearby areas without urchins. Faunal species richness was comparatively low in barrens habitat, with C. rodgersii grazing activity resulting in an estimated minimum net loss of approximately 150 taxa compared with intact macroalgal habitats.

Reef Life Survey (RLS): Invertebrates

[This data has been superseded by a synthesised global dataset which includes additional ecological data contributed by non-RLS entities (National Reef Monitoring Network). Please visit the corresponding NRMN Collection (IMOS - National Reef Monitoring Network Sub-Facility - Global mobile macroinvertebrate abundance) for the most current version of this data. See "Downloads and Links" section below.] Reef Life Survey is designed to develop and resource a network of skilled recreational divers for rapid and cost-effective assessment of the state of the inshore marine environment at the global scale. The project uses standardised underwater visual census methods employed by trained SCUBA divers to survey fish and invertebrate species and to record habitat type using photo quadrats - this dataset refers to the cryptic fish and invertebrate survey component only. This data has been superseded by the NRM collection "IMOS - National Reef Monitoring Network - Global mobile macroinvertebrate abundance": see https://catalogue-imos.aodn.org.au/geonetwork/srv/eng/catalog.search#/metadata/48cf3cb9-caa9-4633-9baa-8bba3c4d904a

Natural growth lines in sea urchin (Heliocidaris erythrogramma) ossicles

Sea urchin tagged using tetracycline display visible marks in jaw elements and test plates that can be used to determine growth and subsequently an individuals age. Natural growth lines in the same structures can be used to determine age if natural lines are deposited at a consistent rates independent of age. Sea urchins were tagged using tetracycline and age determined from both fitted growth models and the number of bands deposited. Rates of natural line deposition were also quantified.

The Fishery Biology and Population Dynamics of the pale octopus (Octopus pallidus)

The data was collected from 2 years of field sampling from the commerical octopus (Octopus pallidus) fishery in NW Tasmania in Bass Strait. The data consists of morphological, reproductive and ageing information.

Utilisation of the introduced New Zealand screwshell (Maoricolpus roseus) by native hermit crabs in eastern Tasmania - depth-related variance in shell occupancy

Interactions between native and introduced species can help to elucidate the impact of exotic species on the broader community. This work examines utilisation of an introduced gastropod, the New Zealand screwshell (Maoricolpus roseus) by native hermit crabs in eastern Tasmania. Variation in shell occupancy by hermit crabs was examined across different depths (10, 20, 30 and 40m) within a single site (Dennes Point, SE Tasmania). Sediment cores were taken from 10 and 20 m to compare sediment size structure. A sediment preference trial using the hermit crab Paguristes tuberculatus was also carried out (using sediment from 10m and 20m) to try and determine the low level of hermit crab occupancy at 20m (compared with that at 10m).

2008