RECRUITMENT
Type of resources
Topics
Keywords
Contact for the resource
Provided by
-
Increased ultraviolet radiation (UV-A and/or UV-B) may impact on the establishment and structure of a shallow water benthic invertebrate assemblages. A global experiment in more than 8 countries, using an identical methodology (transparent UV filters) will add significantly to our understanding of the impacts of anthropogenically induced global change on natural systems. To appraise the effects of increased UVR on shallow marine benthic assemblages, five experimental rafts were deployed in protected bays west of Shirley Island near Casey Station, Antarctica (66.16oS 110.30oE). Each raft consisted of eight experimental units, each of which contained a colonization panel (ceramic tile) positioned horizontally and submerged 4-6 cm underwater. Irradiation treatments were randomly assigned to each unit with the use of UV cut-off filters. The treatments were as follows: No UVR (transmits photosynthetically active radiation or PAR, 400-700nm), No UVB (transmits PAR + UVA, 320-700nm), Perspex (full spectrum, 280-700nm, procedural control), or No filter (full spectrum, treatment control). In addition there were three levels of consumer treatments: With consumption (container sides removed), without consumption (container sides perforated with 4 mm holes), and a control (3 sides perforated, 1 side removed). After seven weeks tiles were removed to the laboratory for examination. All tiles were dominated by diatoms and no sessile invertebrates were apparent. The first trial has been completed, but several other panels are still in place. A conference will be held in early 2002 between participating countries to discuss results and findings. The 2001\2002 summer season consisted of experimental designs divided up into three separate projects. The aims were all to provide a corrollary to the previous seasons data. Project 1 consisted of the extraction and redeployment of settlement depth arrays situated in Geoffrey's Bay and Hollin Island Channel. Due to prevailing weather conditions resulting in limited boating hours and diving program, only one array was retrieved. On inspection of the array it was decided to deploy further replicates to gain a better temporal understanding of the communities. Projects 2 and 3 consisted of a similar experimental design, however monitoring the shallower depths of settlement (depths of 1m and 2m below sea level) for a period of one month. Project 2 consisted of arrays with two depths and 2 panels per depth, triple replicated, under the icesheet in O'Brien Bay and Shirley Channel, with a substrate depth of 20m. Diatom samples are to be analyzed in Australia. Project 3 was of a similar design to project 2 though it was measuring recruitment in shallow open water. The two sites consisted of Noonan Cove and Geoffrey's Bay at substrate depths of 5m. These tiles are also to be analyzed on return to Australia. There were 5 rafts used in this study - they are listed as R1 to R5 there were two factors in the design -(i) predator access: Caged (C) Half caged (H) and Open (O) and ii) UV exposure: Perspex (P), Macrolon (M), No filter (N) and Film + perspex (F). A list of the diatoms found on the settlement panels is provided at the URL below. The fields in this dataset are: Species Sample
-
The recruitment of mobile epifauna on hard-substratum was examined in a field experiment using tiles. A total of 160 tiles were deployed at five locations, with 32 tiles at each location, arranged in a spatially nested design. There were three potentially impacted locations locations (two in Brown Bay and one in Shannon Bay) and two control locations (in O'Brien Bay). This metadata record describes data from the first sampling time only. Eight tiles were collected from each location 15 months after the initial deployment. The experiment was setup so that the combined recruitment of mobile epifauna to the upper and lower sides of the tiles could be examined. The sessile epifauna on the tiles were also collected and are described in a separate metadata record. A total of 40 samples are included in this data. Also links to ASAC 1100.
-
The recruitment of epifauna (sessile and mobile) on hard-substratum was examined in a field experiment using tiles. A total of 160 tiles were deployed at five locations, with 32 tiles at each location, arranged in a spatially nested design. There were three potentially impacted locations locations (two in Brown Bay and one in Shannon Bay) and two control locations (in O'Brien Bay). This metadata record describes data from the first sampling time only. Eight tiles were collected from each location 15 months after the initial deployment. The experiment was setup so that recruitment of sessile epifauna to both the upper and lower sides of the tiles could be examined. The mobile epifauna on the tiles were also collected and are described in a separate metadata record. Heavy recruitment was observed on the underside of the tile and only light recruitment was observed on the upper surface. Also links to ASAC 1100.
-
A survey of the epibenthic fauna of hard-substrata was made around Casey Station, using a camera mounted on a frame to take photoquadrats. A nested sampling design was used with several spatial scales. At each location there were two sites, approximately 50-100 m apart. At each site there were three by 15 m long transects, approximately 5 m apart. On each transect there were 2 plots, 5 m long by 2 m wide. Six photoquadrats were taken in each plot. This metadata record describes one component of this survey, photoquadrats taken in flat or gently sloping rocky areas, where the bottom consisted of flat bedrock, gravel or cobbles. A separate survey was done in and around boulders and boulder fields. One of the aims of this survey was to determine if there is any evidence of human impacts in these assemblages. There were several control and several potentially impacted locations. The data have yet to be analysed. Also links to ASAC 1100.
-
The effect of location and sediment contamination on recruitment of soft-sediment assemblages were examined in field experiment at Casey Station, East Antarctica. Four locations were used, a polluted bay adjacent to an old disused tip site (Brown Bay), a bay adjacent to the Casey Station sewage outfall, and two undisturbed control locations in O'Brien Bay. At each location two types of defaunated sediment (polluted and control) were placed 12 - 18 m, in experimental trays. Half of the experimental sediments were left in place over the Austral winter, from March - November, and the remaining sediments were collected after a total of one year, in February 1999. There were large differences in recruitment between the two locations and significant differences between the polluted and control sediment. There were not only differences in abundance of taxa and assemblage structure but also in spatial variability and variability of populations of certain taxa, with recruitment to the control locations more variable than polluted locations, and recruitment in the control sediment more variable than the polluted sediment. The majority of fauna recruiting to the experiment were highly motile colonizing species with non-pelagic lecithotrophic larvae, usually brooded and released as dispersing juveniles, such as gammarids, tanaids, isopods and gastropods. A total of 64 recruitment samples were collected after 9 months and 52 samples after one year. Samples were sieved at 500 micro m and sorted mainly to species. Samples are rows in data sheet. Site codes include place name (e.g. BB2) and experimental treatment (e.g. C1 - control 1). See accompanying sheet for full details of codes, including species names. Sediment chemistry data are means (and standard errors) for each treatment (averaged over 2 trays). Also links to ASAC 1100. The fields in this dataset are: Species Site Sample Abundance Toxicity Arsenic Cadmium Copper Lead Silver Zinc
-
The effects of hyrdocarbon and heavy metal contamination of marine sediments on recruitment of soft-sediment assemblages were examined in a field experiment at Casey Station, East Antarctica. Three locations were used, a polluted bay adjacent to an old disused tip site (Brown Bay) and two control locations (O'Brien Bay and Sparkes Bay). At each location three types of defaunated sediment (hydrocarbon treated, heavy metal treated and control) were placed at approximately 15 m depth and left in place for 3 months, from December to February. Sediments were artificially contaminated with hydrocarbons and metals at concentrations which were representative of levels found in sediments at contaminated sites around Casey Station. There were large differences in recruitment between the three locations and significant differences between the control and contaminated sediment. Sediments in the experiment were also examined for evidence of degradation and attenuation of hydrocarbons and heavy metals. A total of 104 recruitment samples were collected. Samples were sieved at 500 micro m and sorted mainly to species. Other work to arise from this experiment includes examination of the effects on diatom communities and microbial communities. Data includes fauna, metals and hydrocarbon concentrations in experiment. Pre-deployment concentrations (before experiment was deployed in water) are indicated as 'pre-deployment'. Concentrations of contaminants in sediments surrounding the experiment (within several metres) are indicated as 'surrounding'. This project also links to ASAC 1100. The fields in this dataset are: Location Site Treatment (tmt) Site and replicate Species Toxicity Arsenic Cadmium Copper Lead Silver Zinc Special Antarctic Blend Fuel (SAB) Lube TPH
-
The effect of location, depth and sediment contamination on recruitment of soft-sediment assemblages were examined in a pilot experiment at Casey Station, East Antarctica. Two locations were used, a polluted bay adjacent to an old disused tip site (Brown Bay) and an undisturbed control (O'Brien Bay). At each location two types of defaunated sediment (polluted and control) were placed at 2 depths, 15 m and 25 m. Sediments were left in place over the Austral winter, from March - November. There were large differences in recruitment between the two locations and depths and some differences between the two sediment types. Brown Bay had greater recruitment than O'Brien Bay. Shallow sites had generally greater recruitment than deep, but deep sites had greater diversity (H'), richness (d) and evenness (J'). Control sediment recruited greater numbers of arthropod, gammarid and isopod taxa. There were not only differences in abundance of taxa and assemblage structure but also in spatial variability and variability of populations of certain taxa, with recruitment to the control and deep locations more variable, and recruitment in the control sediment more variable than the polluted sediment. Recruitment was influenced by a combination of location, depth and sediment type. There is some evidence of an environmental impact at the polluted site. The majority of fauna recruiting to the experiment were highly motile colonizing species with non-pelagic lecithotrophic larvae, usually brooded and released as dispersing juveniles, such as gammarids, tanaids, isopods and gastropods. A total of 56 recruitment samples were collected. Samples were sieved at 500 micro metres and sorted mainly to species. Metal concentrations and total organic carbon concentrations are also included. Also links to ASAC 1100. The fields in this dataset are: Species Location Site Treatment (tmt) Site and replicate Toxicity Arsenic Cadmium Copper Lead Silver Zinc