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Day 1 - Marine benthic science

Title: Why is East Antarctica so important? A marine biological perspective

Presenter and Author: Nerida Wilson

Australian Museum, Sydney, 6 College St, nerida.wilson@austmus.gov.au

Abstract

Although Antarctica represents a reasonably isolated and stable ecosystem compared to other global locations, there are reasons to believe that this may change in the future. At present, there are some significant gaps in understanding marine benthic communities, which hampers our ability to understand what we may be able to protect and manage. The majority of marine benthic studies have taken place around the Antarctic Peninsula or the Ross Sea, which reflects primarily on the availability of infrastructure. In particular, understanding the dispersal patterns of populations and how they may be connected within East Antarctica is lacking. These types of organisms are not suitable for traditional methods of measuring dispersal, and we must rely on genetic methods to estimate connectivity. Here I present case studies that demonstrate why there is a taxonomic imperative to sample more broadly in East Antarctica, and why this underpins our ability to effectively monitor conservation efforts into the future.


Title: Success of Antarctic bivalve populations in a changing ocean: results of experiments and models

Presenter: Vonda Cummings

National Institute of Water and Atmospheric Research

Authors: VJ CUMMINGS1*, CI GUY1,2, VJ METCALF3, JE HEWITT4, N BARR1, P HEATH1

1 - National Institute of Water and Atmospheric Research, Wellington, New Zealand, *v.cummings@niwa.co.nz

2 - University of London, University Marine Biological Station Millport, Isle of Cumbrae, Scotland

3 - Department of Wine, Food and Molecular Biosciences, Lincoln University, Christchurch, New Zealand

4 - National Institute of Water and Atmospheric Research, Hamilton, New Zealand

Abstract

Increases in ocean pCO2 (‘ocean acidification’) and temperature are predicted for the global oceans within this century, with the rate and magnitude of change expected to be highest in polar regions. The physiological and ecological impacts of ocean acidification on high latitude benthic calcifiers are, as yet, poorly understood. Laternula elliptica and Adamussium colbecki are common around Antarctica, and are functionally important bivalves in Ross Sea coastal benthic ecosystems. They have different life history traits and shells constructed of different carbonate polymorphs; characteristics which may render them differentially susceptible to ocean acidification. Separate, four month-long laboratory experiments compared physiological and metabolic responses of adult stages of each species, at existing pCO2 levels (determined from field measurements), with those predicted to occur in the following decades, and, for Laternula, past conditions (glacial). A variety of response variables were assessed, including shell synthesis, metabolism and stress, via measurements of enzyme activity, respiration rates, protein synthesis and overall condition. We found clear negative effects on the functioning of both species. Population dynamics modelling was then used to describe the potential implications of ocean acidification (gleaned from our experiments), and ocean warming (from the literature), on survivorship and reproductive output of both species. Results suggest impacts of future ocean change on the long term success of populations of both species.


Title: Vulnerability of the fertilisation and calcifying larval stages of Antarctic sea urchins to near-future ocean acidification and warming

Presenter: Melanie Ho

Schools of Medical and Biological Sciences, University of Sydney

Authors: Ho, M.A.1, Koleits, L.2, Price, C.2, King, C.K.3, Virtue, P.2, Tilbrook, B.4, Lamare, M.5, Byrne, M.1

1 - Schools of Medical and Biological Sciences, University of Sydney, Sydney, NSW, Australia, melanielaa@gmail.com, mbyrne@anatomy.usyd.edu.au

2 - Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia, lkoleits@gmail.com, caprice78@gmail.com, p.virtue@utas.edu.au

3 - Australian Antarctic Division, Kingston, Tasmania, Australia, Cath.King@aad.gov.au

4 - CSIRO Marine and Atmospheric Research, Hobart, Tasmania, Australia, Bronte.Tilbrook@csiro.au

5 - Department of Marine Biology, University of Otago, Dunedin, New Zealand, miles.lamare@otago.ac.nz

Abstract

Little is known about potential synergistic effects of concurrent ocean warming and acidification on the development of stenothermal polar marine invertebrates. We examined the effects of these stressors on Antarctic sea urchins in context with ocean change projections. For Sterechinus neumayeri, effects of warming and acidification on fertilization was investigated across three temperatures, three pH and five sperm:egg ratio treatments. Fertilization was only negatively affected by sperm density and was enhanced by warming. For development to the calcifying larval stage, principle coordinates analysis on five larval metrics in embryos reared in two temperature and three pH levels showed a significant effect of temperature and pH on the pattern of larval growth. Growth was accelerated by temperature with a 20-28% increase in postoral (PO) length at +2°C across all pH levels but was strongly depressed by reduced pH with 8-19% decrease in PO length at pH 7.6-7.8 at both temperatures. However, development in S. neumayeri was particularly sensitive to increased temperature as seen in altered larval allometry at just +2°C warming. Decreased pH also disrupted developmental patterning as seen in increased larval left-right asymmetry. Altered body shape impairs feeding in echinoplutei. For two Abatus species, A. ingens and A. shackletoni, effects of warming and acidification on juvenile growth was investigated. Juvenile spine growth of both species was negatively affected by decreasing pH. Spine growth in juvenile A. ingens and A. shackletoni reared in the most extreme treatment (1°C/pH 7.6) decreased by 28% and 24% respectively.


Title: Coral proxies of environmental variability and change in SO ecosystems: current and potential applications

Presenter: Ronald Thresher

CSIRO Wealth from Oceans Flagship

Authors: Ronald Thresher1, Kelly Strzepek2, Helen Neil3, Stewart Fallon2

1 - CSIRO Wealth from Oceans Flagship, Hobart, Tasmania 7001, Ron.Thresher@csiro.au

2 - Research School of Earth Science, Australian National University, Canberra, ACT, kelly,strzepek@anu.edu.au, stewart.fallon@anu.edu.au

3 - National Institute of Water and Atmosphere, Greta Point, New Zealand, Helen.Neil@niwa.co.nz

Abstract

Instrumental records for ecosystem dynamics and oceanography are too short and incomplete to easily distinguish between natural variability and trends caused by anthropogenic forcing. This information gap can be at least in part closed by analysis of proxy records in the carbonate and organic fractions of skeletons of long-lived (up to millennia) colonial corals widely distributed in the SO. Bamboo corals (gorgonians) in particular appear to be potentially valuable sources of information, with skeletal proxies proposed for ambient water temperature, salinity, nutrient supply, water mass tracers, pH and food-web structure, as well as providing multi-decadal data on variability in their own growth rates. In this talk we review the current status of on-going joint Australia/New Zealand studies on proxies in SO bamboo corals and their links to historical climate variability, highlight examples of work in progress on novel efforts to reconstruct ecosystem processes and oceanography, and suggest future applications of the approach that might unprecedented high resolution historical reconstructions spanning the SO.


Title: Prediction of Deep-Sea sessile Benthic epifauna across the Kerguelen Plateau

Presenter: Ty Hibberd

Australian Antarctic Division

Authors: Ty Hibberd and Steve Candy
Australian Antarctic Division, 203 Channel Highway, Kingston, Tasmania 7050 Australia ty.hibberd@aad.gov.au

Abstract

Sessile benthic invertebrates like sponges and corals form key components of marine biodiversity in the deep Southern Ocean. Yet their distribution and extent across seascapes, and factors influencing their spatial ecology, are not well understood. In this study, 129 quantitative samples from the Heard Island and McDonald Islands (HIMI) region on the central Kerguelen Plateau were used to assess the potential causal relationship between sessile epifauna and their associated environments, and to evaluate for the first time the efficacy of these bio-physical relationships for extrapolating their distribution and biomass across seascapes of the deep Southern Ocean. Biomass and the co-located attributes of the environment were used to parameterise Generalised Linear Models (GLM) for key sessile groups. The GLM revealed consistent and predictable relationships between several of these groups and facets of the physical environment, namely depth. Synoptic data on correlated physical variables was subsequently used by the GLM to predict the distribution of biomass across HIMI. Estimates revealed high biomasses of sessile epifauna above 300 m, and where physical parameters were likely to provide favourable attachment and feeding conditions, like on the western banks and rugose slopes south of Heard Island. In the depths of 500 – 1000 m, biomass was lower and patchier, and below 1000 m the seabed appeared relatively devoid of these sessile taxa. The framework provided a valuable tool for estimating plausible values of biomass of sessile fauna in areas were biological data was not available, offering the data necessary to assist with managing Southern Ocean benthic biodiversity.


Title: Seafloor habitats and associated benthic communities in the near-shore environment of the Vestfold Hills, East Antarctica

Presenter: Jodie Smith

Geoscience Australia

Authors: Jodie Smith1, Philip O’Brien2, Jonny Stark3, Glenn Johnstone3

1 - Geoscience Australia, GPO Box 378, Canberra ACT 2601, jodie.smith@ga.gov.au

2 - Department of Environment and Geography, Macquarie University, Sydney, NSW 2109, phil.obrien.ant@gmail.com

3 - Australian Antarctic Division, 203 Channel Highway, Kingston, Tasmania 7050 Australia, jonny.stark@aad.gov.au, glenn.johnstone@aad.gov.au

Abstract

An integrated analysis of geoscience information and benthos data has been used to identify seafloor habitats and associated benthic communities in the near-shore environment of the Vestfold Hills, East Antarctica. A multibeam echo-sounder was used to collect high-resolution bathymetry of the seafloor to depths of 215 m. A towed underwater video was used to identify macrobenthos along 16 transects. Abiotic variables including depth, backscatter intensity, substrate, slope, seafloor features (e.g. iceberg scours, sand ripples) and latitude were extracted from the multibeam and video datasets. Multivariate analysis of the benthos data was used to identify discrete benthic communities within the study area. Analysis of bio-physical relationships indicates that these benthic communities occur within distinct geographical regions and seafloor habitats. The habitats are distinguished primarily on the basis of depth and substrate. The two dominant seafloor habitats and associated benthic communities are:
1) deep, muddy basins with low to medium biological cover, consisting predominantly of bivalves, urchins, and seapens; and 2) shallow rocky outcrops, typically covered in dense macroalgae communities and associated invertebrates such as amphipods, spirorbid polychaetes and holothurians. In between are transition zones which provide habitat to mixed benthic communities. This study demonstrates the efficacy of using multibeam systems to survey large areas of the seafloor and collect high-resolution baseline data across previously unexplored regions. This baseline data is critical to improve our understanding of ecosystem dynamics and the relationships between biota and habitats and allows managers to make informed decisions about the effects of different activities on marine habitats.

Latest news

  • Conference prize winners
    27 Jun 2013

    The Strategic Science in Antarctica conference concluded yesterday and two days of workshops have commenced. Congratulations to those who were awarded prizes for their contributions to the conference.

  • Watch the welcome message from Australia's Environment Minister
    24 Jun 2013

    In a welcome message via video from Canberra, Australia’s Environment Minister, Tony Burke, reflected on the foresight of earlier decision-makers who agreed to set aside an entire continent for scientific research.

  • Last minute information for attendees
    20 Jun 2013

    There's not too long to wait until the start of the Strategic Science in Antarctica conference, and we hope you’re as excited as we are! Read on for more information about the final program, registration, Twitter, presenters, posters and social functions.

More news…

Key dates

  • 11th June 2013
    Registrations close
  • 21st June 2013
    Registrations at the AAD open for staff
  • 24th June 2013
    Registrations at the venue open
  • 24th June 2013
    Conference commences
  • 26th June 2013
    Conference concludes

More key dates…

This page was last modified on 6 June 2013.