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Seabirds are long-range transporters of nutrients and contaminants, linking marine feeding areas with terrestrial breeding and roosting sites. By depositing nutrient-rich guano, which acts as a fertiliser, seabirds can substantially influence the terrestrial environment in which they reside. However, increasing pollution of the marine environment has resulted in guano becoming similarly polluted. Here, we determined metal and metalloid concentrations (As, Cd, Cr, Cu, Hg, Pb) in Flesh-footed Shearwater (Ardenna carneipes) guano, soil, terrestrial flora, and primary consumers and used an ecological approach to assess whether the trace elements in guano were bioaccumulating and contaminating the surrounding environment. Concentrations in guano were higher than those of other Procellariiformes documented in the literature, which may be influenced by the high amounts of plastics that this species of shearwater ingests. Soil samples from shearwater colonies had significantly higher concentrations of all metals, except for Pb, than soils from control sites and formerly occupied areas. Concentrations in terrestrial primary producers and primary consumers were not as marked, and for many contaminants there was no significant difference observed across levels of ornithogenic input. We conclude that Flesh-footed Shearwaters are transporters of marine derived contaminants to the Lord Howe Island terrestrial environment.
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Parks Australia - Our Marine Parks Grants Round 2 Project: Nearshore marine habitat mapping of the Norfolk Marine Park (Grant Activity ID: 4-FIZ391E) The Norfolk Marine Park is the is the eastern-most Park in the Temperate East Network of Australian Marine Parks, located between the NSW coast and Norfolk Island. The Park encompasses 188,444 km² of ocean and ranges in depth from 0 m at the Norfolk Island high tide mark to more than 5,00 m off the edge of the Norfolk Ridge. The Park includes two key ecological features – the Norfolk Ridge, and the Tasman Front and associated eddy field – both of which are valued for their high productivity, aggregations of marine life, biodiversity, and endemism. Norfolk Marine Park supports a range of species, including those listed as threatened under the Environment Protection and Biodiversity Conservation (EPBC) Act (1999), and contains Biologically Important Areas for breeding, foraging, and migration of seabirds, marine turtles, and humpback whales. The objective of this project was to create the first marine habitat map for the nearshore shallow water surrounding Norfolk, Nepean, and Phillip Islands. This was conducted in collaboration with Norfolk residents to provide local knowledge input and to ground-truth the remotely-sensed habitat mapping. This high-level habitat map will be used for planning purposes, development applications, and EPBC Act referrals within the nearshore waters of the Norfolk Marine Park, where no specific zoning for recreational and commercial activities currently exists. The map provides a basis for any ongoing citizen-science-driven marine habitat impact and condition assessments, ecosystem monitoring, and to provide the Norfolk Island residents with ownership of any future zoning planning. The map can be further refined as more detailed information becomes available from subject matter experts in the future.
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Ocean Infinity (Australia) Pty Ltd (formerly iXblue Pty Ltd), in partnership with Deakin University’s Marine Mapping Group, University of Wollongong, Tellus4D Geoimaging, University of Newcastle, University of New South Wales, University of Tasmania, and Geoscience Australia, undertook a combined aerial and hydrographic survey as part of the Norfolk Island Nearshore and Coastal Habitat Mapping project under Parks Australia Grant Activity ID 4-FISKTDM. The work aimed to establish a detailed baseline of Norfolk Island’s nearshore coastal and shelf environments to inform management, conservation, and research. From 21 to 24 July 2021, 109 km² of the Norfolk Shelf was mapped using high-resolution multibeam sonar, along with two sub-bottom profiles. These were supplemented by 44 Baited Remote Underwater Video (BRUV) deployments in the northeast and south of the island to assess fish assemblages and provide ground truthing data for interpretation of seabed nature. In November 2021, a separate coastal survey using high-resolution drone photogrammetry captured geomorphic and habitat information at seven coastal sites: Captain Cook Lookout, Anson Bay, Puppy’s Point, Headstone Point, Slaughter Bay and Bombora Beach, and Cemetery and Emily Bay. These locations span a variety of morphologies, from exposed basaltic shore platforms and dramatic cliffs to offshore stacks and pockets of rocky beach. The data collected by the project provides a detailed view of the marine and coastal geomorphology of Norfolk Island. The data provides an initial condition assessment of key areas to inform park management, habitat protection, and future targeted studies such as further bathymetric mapping in sensitive areas and expanded ground-truthing of seabed habitats.
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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.
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Invasive mammal eradications are commonplace in island conservation. However, post-eradication monitoring beyond the confirmation of target species removal is rarer. Seabirds are ecosystem engineers on islands and are negatively affected by invasive mammals. Following an invasive mammal eradication, the recovery of seabird populations can be necessary for wider ecosystem recovery. Seabirds fertilise islands with isotopically heavy nitrogen, which means nitrogen stable isotope analysis (δ15N) could provide a useful means for assessing corresponding change in ecosystem function. We quantified decadal changes in δ15N on eight temperate New Zealand islands subject in pairs to distinct mammal invasion and seabird restoration histories: invaded, never-invaded, invader-eradicated and undergoing active seabird restoration. First, we investigated long-term changes in δ15N values on individual islands. Second, we used a space for time analysis to determine if δ15N levels on islands from which invaders had been removed eventually recovered to values typical of never-invaded islands. On each island soil, plants (Coprosma repens, C. robust and Myrsine australis) and spiders (Porrhothelidae) were sampled in 2006/07 and 2022 allowing δ15N change on individual islands over 16 years to be assessed. Combined, the samples from invader-eradicated islands provided a 7 – 32 year post-eradication dataset. Change in δ15N was only detected on one island across the study period, following the unexpected recolonisation of seabirds to an invaded island. Invader-eradicated islands generally had higher δ15N values than invaded islands however, they were still lower than never-invaded islands and there was no trend in δ15N with time since eradication. This, and the measurable increase in δ15N following seabird recolonisation on one island, may suggest that δ15N change occurs rapidly following invader-eradication, but then slows, with δ15N values staying relatively constant in the time period studied here. Isotope and seabird population studies need to be coupled to ascertain if plateauing in δ15N reflects a slowing of seabird population growth and subsequent basal nutrient input, or if the baseline nutrients are entering the ecosystem but then not propagating up the food web.
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We compare the formulation and emergent dynamics of 11 CMIP6 IPCC marine biogeochemical models. We find that the largest source of uncertainty across model simulations of marine carbon cycling is grazing pressure (i.e. the phytoplankton specific loss rate to grazing). Variability in grazing pressure is driven by large differences in zooplankton specific grazing rates, which are not sufficiently compensated for by offsetting differences in zooplankton specific mortality rates. Models instead must tune the turnover rate of the phytoplankton population to balance large differences in top-down grazing pressure and constrain net primary production. We then run a controlled sensitivity experiment in a global, coupled ocean-biogeochemistry model to test the sensitivity of marine carbon cycling to this uncertainty and find that even when tuned to identical net primary production, export and secondary production remain extremely sensitive to grazing, likely biasing predictions of future climate states and food security.
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We hypothesised that New Zealand sea lions from Campbell Island/Motu Ihupuku of various sex and age classes would utilise the water column differently due to differing physiological constraints and therefore have different accessibility to prey resources. We tested whether sea lion diving behaviour varied in relation to (i) age and sex class, (ii) time of day and (iii) water depth. We also hypothesized that the proportion of benthic/pelagic diving, and consequently risk of fisheries interaction, would vary in relation to age and sex. Satellite telemetry tags were deployed on 25 NZSL from a range of age/sex classes recording dive depth, duration and location. Adult females and juveniles used inshore, benthic habitats, while sub-adult males also utilised benthic habitats, they predominantly used pelagic habitat at greater distances from the island. Adult females and juveniles exhibited shorter dives than the same age/sex classes at the Auckland Islands, suggesting a lower dive effort for these age/sex classes at Campbell Island.
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1. Workforce Tasmania’s commercial fishing industry workforce is defined as those people engaged in economic activity (work) within the sector across or at a given time, either in paid employment or self-employment. For fisheries this includes skippers and crew employed as sub-contractors and paid on a share of catch arrangement. It can include people engaged in unpaid work undertaken as part of these activities, although this has not been included in this assessment. Monitoring workforce changes is important because these changes indicate changes in social and economic benefits at a statewide and regional community level. Factors which affect workforce size include the extent to which a policy of maximizing technical efficiency is pursued through management, which typically reduces the fleet size and therefore the number of people employed. Other factors include the level of stock availability and access, the cost of entry into the fishery, and the financial profitability of fishing. Because of these factors, many fishers are engaged in employment in multiple fisheries or other marine sectors in order to supplement fishing incomes and pursue full-time employment. 1.1. Abalone The commercial harvesters catching abalone species operate within the Tasmanian Abalone Fishery. Assessment of workforce indicators is undertaken at fishery level. The data provided for this fishery is for the Tasmanian Abalone Fishery as a whole, which includes harvesting activity for this species as well as all other species caught in this fishery. 1.2. Commercial Dive species The commercial harvesters catching these species operate within the Tasmanian Commercial Dive Fishery. Assessment of workforce indicators is undertaken at fishery level. The data provided here is for the Tasmanian Commercial Dive species as well as all other species caught in this fishery. 1.3. Giant crab species The commercial harvesters catching giant crab operate within the Tasmanian Giant Crab Fishery. Assessment of workforce indicators is undertaken at fishery level. 1.4. Scalefish species The commercial harvesters catching this scalefish species operate within the Tasmanian Scalefish Fishery. Assessment of workforce indicators is undertaken at fishery level. The data provided here is for the Tasmanian Scalefish Fishery as a whole, which includes harvesting activity for this species as well as all other species caught in this fishery. 1.5. Scallop species The commercial harvesters catching species of scallop operate within the Tasmanian Scallop Fishery. Assessment of workforce indicators is undertaken at fishery level. 1.6. Southern rock lobster The commercial harvesters catching southern rock lobster operate within the Tasmanian Rock Lobster Fishery. Assessment of workforce indicators is undertaken at fishery level. 2. Workforce Indicators 2.1. Persons Workforce size (the total number of people directly employed) includes both skippers and crew, and those employed full time and part time. 2.2. Employment FTE The number of Full Time Equivalent (FTE) positions in each fishery is also estimated. This indicator shows that while a higher number of people may be employed in a fishery, some of these jobs may be part-time. Therefore, the number of FTEs is typically lower than the number of people in the workforce. In this iteration of the dataset, this value is unavailable for the abalone fishery in 2016, 2017, and 2019, and does not apply to the scallop fishery in any of the years available (2016-2020). 2.3. Active Supers The number of supervisors (skippers) employed in the fishery. 2.4. Harvest Units (TAS HP) The number of harvest units (combination of licensed vessel and fishing entitlement) active in a fleet and the number of people who actively harvest fish as supervisors (skippers) in a commercial fishery are directly linked to the size of the workforce in each fishery. In many cases, multiple supervisors may be linked to the same harvest unit, so the number of supervisors is often higher.
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Ocean alkalinity enhancement (OAE) is an emerging carbon dioxide removal (CDR) strategy that leverages the natural processes of weathering and acid neutralisation to durably store atmospheric CO2 in seawater. OAE can be achieved with a variety of methods, all of which have different environmental implications. One widely considered method utilizes electrochemistry to remove strong acid from seawater, leaving sodium hydroxide (NaOH) behind. This study evaluates the impacts of OAE via NaOH (NaOH-OAE) on a coastal plankton bloom, with particular focus on how macronutrient regeneration in the aftermath of the bloom responds to the perturbation. To investigate this, we enclosed a natural coastal phytoplankton community, including coccolithophores, in nine microcosms. The microcosms were divided into three groups: control, unequilibrated (512.1 ± 2.5 µmol kg-1 alkalinity increase) and equilibrated (499.3 ±5.65 µmol kg-1 alkalinity increase). Light was provided for 11 days to stimulate a bloom (light phase) and lights were turned off thereafter to investigate alkalinity and nutrient changes for 21 days (dark phase). We found no detectable effect of equilibrated NaOH-OAE on phytoplankton community and bacteria abundances determined with flow cytometry but observed a small yet detectable restructuring of phytoplankton communities under unequilibrated conditions. NaOH-OAE had no significant effect on alkalinity, NOx- and phosphate regeneration, but increased silicate regeneration by 64% over 21 days under darkness in the unequilibrated treatments where seawater pH was highest (8.65 relative to 7.92 in the control). Additional dissolution experiments with two diatom species supported this outcome on silicate regeneration for one of the two species, thereby suggesting that the effect is species specific. Our results point towards the potential of NaOH-OAE to influence regeneration of silicate in the surface ocean and thus the growth of diatoms, at least under the very extreme NaOH-OAE conditions simulated here.
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Phytoplankton indirectly influence climate through their role in the ocean biological carbon pump. In the Southern Ocean, the subantarctic zone represents an important carbon sink, yet variables limiting phytoplankton growth are not fully constrained. Using three shipboard bioassay experiments on three separate voyages, we evaluated the seasonality of iron (Fe) and manganese (Mn) co-limitation of subantarctic phytoplankton growth south of Tasmania, Australia. We observed a strong seasonal variation in a phytoplankton Fe limitation signal, with a summer experiment showing the greatest response to Fe additions. An autumn experiment suggested that other factors co-limited phytoplankton growth, likely low silicic acid concentrations. The phytoplankton responses to Mn additions were subtle and readily masked by the responses to Fe. Using flow cytometry, we observed that Mn may influence the growth of some small phytoplankton taxa in late summer/autumn, when they represent an important part of the phytoplankton community. In addition, Mn induced changes in the bulk photophysiology signal of the spring community. These results suggest that the importance of Mn may vary seasonally, and that its control on phytoplankton growth may be associated with specific taxa.