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In this dataset, we compared growth of Fraglariopsis cylindrus and Phyaeocystis antarctica collected from coastal and open ocean water at 3 °C, 5 °C and 7 °C, with and without additions of 5 nM dFe(II).
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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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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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Data to accompany publication on wild diet of southern rock lobster on the east coast of Tasmania. In this study we collected 64 lobsters and analysed the diet of each individual using stomach contents, stable isotope analysis and DNA identification of prey species in faecal samples.
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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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At the inception of our project, no study had examined particle fluxes in the Subantarctic Zone (SAZ) of the Southern Ocean, despite the fact that the SAZ represents a large portion of the total area of the Southern Ocean, serve as a strong sink for atmospheric (~1G t C yr-1 [Metzl et al., 1999]), and is central to hypotheses linking particle fluxes and climate change [Francois et al., 1997; Kumar et al., 1995; Sigman et al., 1999]. The SAZ serves as an interface between the cold nutrient-rich waters to its south and the nutrient-depleted subtropical gyres to its north. SAZ upper layers are marked by a thick layer of relatively homogenous Subantarctic Mode Water (SAMW), which overlies Antarctic Intermediate Water (AAIW). Both water masses are subducted northward beneath the subtropical gyres. Thus particles leaving the surface in these regions contribute to carbon redistribution via both the fraction that reaches the deep sea by settling and the fraction that is remineralized within SAMW or AAIW and subsequently subducted. The SAZ exhibits surface water carbon dioxide partial pressures well below atmospheric equilibrium, but PFZ waters are closer to atmospheric equilibrium in this sector [Metal et al., 1999; Poppet al., 1999]. The relative physical and biological contributions to these carbon dioxide partial pressure variations are unclear, but it is important to determine them because physical and biological carbon dioxide transfers are expected to show different responses to climate change [ Matear et al., 1999; Sarmiento and LeQuere, 1996]. For these reasons we focused on the SAZ and, for comparative purposes, on the PFZ to its south. We measured particle fluxes using moored sinking particle traps at three sites in the SAZ, in the PFZ, and beneath the Subantarctic Front (SAF), which separates them. This record describes particle flux data collected between 2000 and 2001. The NetCDF data contains the following variables. Please note not all variables are supplied in all files, specifically there are not uncertainty estimates and no quality control flags for this data. -----DATA DICTIONARY----- Name, description, units, standard name TIME, time, YYYY-MM-DD, time of sample midpoint TIME_START, time sample open, YYYY-MM-DD, time sample open NOMINAL_DEPTH, depth, m, nominal depth LATITUDE, latitude, degrees_north, latitude of anchor LONGITUDE, longitude, degrees_east, longitude of anchor pressure_actual, actual, dbar, actual pressure sample, sample number, 1, sample number sample_quality_control, quality flag for sample number, unitless, quality flag for sample number mass_flux, <1mm, mg m-2 d-1, particulate total mass flux mass_flux_uncertainty, uncertainty for particulate total mass flux, mg m-2 d-1,), uncertainty for particulate total mass flux mass_flux_quality_control, quality flag for particulate total mass flux, unitless, quality flag for particulate total mass flux SAL_BRINE, supernatant, 1, sample supernatant practical salinity SAL_BRINE_uncertainty, uncertainty for sample supernatant practical salinity, 1, uncertainty for sample supernatant practical salinity SAL_BRINE_quality_control, quality flag for sample supernatant practical salinity, unitless, quality flag for sample supernatant practical salinity pH_BRINE, supernatant, 1, sample supernatant pH NBS scale pH_BRINE_uncertainty, uncertainty for sample supernatant pH NBS scale, 1, uncertainty for sample supernatant pH NBS scale pH_BRINE_quality_control, quality flag for sample supernatant pH NBS scale, unitless, quality flag for sample supernatant pH NBS scale PC_mass_flux, <1mm, mg m-2 d-1, particulate total carbon mass flux PC_mass_flux_uncertainty, uncertainty for particulate total carbon mass flux, mg m-2 d-1, uncertainty for particulate total carbon mass flux PC_mass_flux_quality_control, quality flag for particulate total carbon mass flux, unitless, quality flag for particulate total carbon mass flux PN_mass_flux, <1mm, mg m-2 d-1, particulate total nitrogen mass flux PN_mass_flux_uncertainty, uncertainty for particulate total nitrogen mass flux, mg m-2 d-1, uncertainty for particulate total nitrogen mass flux PN_mass_flux_quality_control, quality flag for particulate total nitrogen mass flux, unitless, quality flag for particulate total nitrogen mass flux POC_mass_flux, <1mm, mg m-2 d-1, particulate organic carbon mass flux POC_mass_flux_uncertainty, uncertainty for particulate organic carbon mass flux, mg m-2 d-1, uncertainty for particulate organic carbon mass flux POC_mass_flux_quality_control, quality flag for particulate organic carbon mass flux, unitless, quality flag for particulate organic carbon mass flux PIC_mass_flux, <1mm, mg m-2 d-1, particulate inorganic carbon mass flux PIC_mass_flux_uncertainty, uncertainty for particulate inorganic carbon mass flux, mg m-2 d-1, uncertainty for particulate inorganic carbon mass flux PIC_mass_flux_quality_control, quality flag for particulate inorganic carbon mass flux, unitless, quality flag for particulate inorganic carbon mass flux BSi_mass_flux, <1mm, mg m-2 d-1, particulate biogenic silicon mass flux BSi_mass_flux_uncertainty, uncertainty for particulate biogenic silicon mass flux, mg m-2 d-1, uncertainty for particulate biogenic silicon mass flux BSi_mass_flux_quality_control, quality flag for particulate biogenic silicon mass flux, unitless, quality flag for particulate biogenic silicon mass flux TIME_END, time sample closed, YYYY-MM-DD, time sample closed Reference, citable reference DOI, DOI
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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.
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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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Location of the Giant Kelp (Macrocystis pyrifera) outplant trial sites. This is part of a collaborative project between IMAS, The Nature Conservancy, CSIRO and NRM South to restore giant kelp forests in Tasmania.