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  • This record presents genetic data underlying the paper 'From the Surface Ocean to the Seafloor: Linking Modern and Paleo-genetics at the Sabrina Coast, East Antarctica (IN2017_V01)' by Armbrecht et al. In this study, we provide the first taxonomic overview of the modern and ancient marine bacterial and eukaryotic communities of the Totten Glacier region, East Antarctica, using a combination of 16S and 18S rRNA amplicon sequencing (modern DNA) and shotgun metagenomic (sedimentary ancient DNA, sedaDNA) analyses, respectively. We explore environmental and geochemical variables that drive these biodiversity patterns. Our data show considerable differences between eukaryote and bacterial signals detected via DNA analyses in the water column vs. the sediments. Organisms that are well represented in deeper waters appear are to have a higher likelihood of becoming preserved in the sediments. The study provides the first assessment of DNA transfer from ocean waters to sediments, while also providing a broad overview of the biological communities occurring in the climatically important Totten Glacier region. (Please note that this record is mirrored in the UTAS Research Data Portal, here: https://rdp.utas.edu.au/metadata/8628529b-49cf-42d4-9459-3c1e97f70d98)

  • The ETAS (Eastern TASmania) model is a high-resolution (~2 km in the horizontal) ocean model for eastern Tasmania, providing three-dimensional estimates of monthly mean temperature, salinity, and circulation over the 1993-2016 period. This dataset consists of temperature, salinity, meridional (N-S), zonal (E-W), vertical, along- and cross-shore currents, density, sea level and net surface heat flux organised into yearly files. A MATLAB script to extract portions of the data is available here: https://github.com/ecjoliver/extractETAS

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    In collaboration with the Tasmanian State Emergency Service, water level monitoring instruments were installed to enable the collection of data in four estuaries identified as being vulnerable to coastal and compound flooding: Derwent Estuary, Huon Estuary, Georges Bay, and Macquarie Harbour. These instruments recorded fluctuations in water levels due to the combined influences of tide, river discharge, and weather events. The effects of the January 2022 Hunga Tonga-Hunga Ha’apai tsunami following a significant submarine volcanic explosion was also recorded in three out of the four estuaries. The datasets, comprising reduced water level observations, predicted water level, and residuals, are available from the IMAS Data Portal. Water level observations of varying duration were recorded between November 2020 – November 2022 for 14 sites in four Tasmanian estuaries. This work was undertaken by Karen Palmer as part of a PhD candidature at the University of Tasmania under the supervision of Dr Christopher Watson, Dr John Hunter, Assoc Prof Hannah Power (University of Newcastle), and Dr Rebecca Harris.

  • We implemented a monitoring program developed by Crawford and White (2006), which was designed to assess the current condition of six key estuaries in NW Tasmania: Port Sorell, the Leven, Inglis, Black, Montagu and Arthur River estuaries. This study considered a range of water quality and ecological indictors commonly used to monitor estuaries. These included: salinity, temperature, dissolved oxygen, turbidity, pH, nutrients (nitrate + nitrite, dissolved reactive phosphorus and ammonia), silica molybdate reactive and chlorophyll a for the water column; chlorophyll a and macroinvertebrate community structure amongst the sediments. The data represented by this record was collected in Arthur River.

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    In fishing trials, the short term survival rates for hook caught flathead (Platycephalus bassensis in Tasmania and P. fuscus in Queensland) were examined to determine critical factors affecting post-release survival. Biological information (size) and hooking location/damage were recorded and fish held for several days in aquaria to assess survival rates. In order to relate hooking location and catch rates for a range of hook types (including circle hooks) structured fishing trials and volunteer fishers (using a diary system) provided information on fish size, hook type and hooking location.

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    Ocean currents are strongly controlled by seafloor topography. Recent studies have shown that small-scale features with slopes steeper than 0.05° significantly affect subsurface eddy velocities and the vertical structure of ocean circulation patterns. Such slope gradients represent the majority of the present-day oceanic basins. Modeling past oceanographic conditions for key climate stages requires similarly detailed paleo seafloor topography grids, in order to capture ocean currents accurately, especially for ocean models with sufficient resolution (<0.1°) to resolve eddies. However, existing paleobathymetry reconstructions use either a forward modeling approach, resulting in global grids lacking detailed seafloor roughness, or a backward modeling technique based on sediment backstripping, capturing realistic slope gradients, but for a spatially restricted area. Both approaches produce insufficient boundary conditions for high-resolution global paleo models. Here, we compute high-resolution global paleobathymetry grids, with detailed focus on the Southern Ocean, for key Cretaceous and early Cenozoic climate stages. We backstrip sediments from the modern global bathymetry, allowing the preservation of present-day seafloor slope gradients. Sediment isopach data are compiled from existing seismo-stratigraphic interpretations along the Southern Ocean margins, and expanded globally using total sediment thickness information and constant sedimentation rates. We also consider the effect of mantle flow on long-wavelength topography. The resulting grids contain realistic seafloor slope gradients and continental slopes across the continent-ocean transition zones that are similar to present-day observations. Using these detailed paleobathymetry grids for high-resolution global paleo models will help to accurately reconstruct oceanographic conditions of key climate stages and their interaction with the evolving seafloor.

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    These data were collected on the RV L'Astrolabe (platform code: FHZI) from 04/11/2005 to 08/11/2005 on a trip from Dumont D'Urville to Hobart. Maximum photochemical efficiency of photosystem II (PSII), also called maximum quantum yield of PSII (Fv/Fm), has become one of the most widely utilized fluorescence parameters in phytoplankton research. It represents the potential photochemical efficiency, which is the probability that the light energy captured by the photosynthetic apparatus is being utilized as photochemistry. Fv/Fm has been shown to have an instant response to variations in physical and chemical properties and is interpreted as a diagnostic of the overall health or competence of phytoplankton. Together with the absorption cross section area of PSII and chlorophyll concentration, it can be used to measure primary production (Cheah et al. 2011, Deep Sea Research). Seawater from 3 m depth was supplied continuously from the ship’s clean seawater line. FRR fluorescence yields were measured continuously at 1 minute intervals in dark-adapted state (! 15 minutes dark-adaptation) using a flash sequence consisting of a series of 100 subsaturation flashlets (1.1 μs flash duration and 2.8 μs interflash period) and a series of 20 relaxation flashlets (1.1 μs flash duration and 51.6 μs interflash period).

  • The predators of Centrostephanus rodgersii, were identified using remote video monitoring. Experiments were performed in two eastern Tasmanian regions, the Maria Island Marine Reserve (MIMR, 42° 35.26'S, 148° 3.03'E) and the Crayfish Point Research Reserve (CPRR, 42° 57.37'S, 147° 21.30'E). The impact of fishing on these predators, and ultimately on C. rodgersii, was examined by comparing survival of C. rodgersii on reefs inside no-take Marine Protected Areas (MPAs) (high predator biomass) relative to fished reefs (low predator biomass). The size-specific nature of predation interactions was examined in context of size-selective fishing pressures within the sea urchin's extended range.

  • A photographic and in situ diver survey of marked incipient Centrostephanus rodgersii barren patches, in eastern Tasmanian, was used to assess any changes in the grazed area and shape at experimental (lobster translocation/ research reserve protection sites; and abalone diver urchin cull sites) versus control sites.

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    A 12-month program was developed and implemented in order to obtain baseline information on water quality (salinity, water temperature, dissolved oxygen, turbidity, pH, dissolved nutrients, silica), ecological condition as shown by Chlorophyll a, benthic macroinvertebrates, pathogens, and habitat extent determined from habitat mapping. Five key estuaries and coastal waters were assessed in the Southern NRM Region of Tasmania. This data includes sampling from Pitt Water / Orielton Lagoon, North West Bay, Port Cygnet, Little Swanport, Moulting Lagoon / Great Swanport.