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Marine Ecosystems

Communities and interactions under the sea

The Marine Ecosystems research group is uniquely placed on the South Island, New Zealand, with access to a broad range of habitats from tropical to polar as well as facilities including ocean-going vessels and research laboratories. As a consequence much of the work that we do takes advantage of environmental gradients to resolve basic structural features of ecosystems and underlying processes.

We carry out empirical research with a focus on metapopulation dynamics, food web structure and biogeochemical cycling in coastal marine systems.

We use direct observations, field sampling, laboratory experiments and environmental chemistry to study marine processes in a broad range of Southern Ocean environments including Coastal Otago, Fiordland, Stewart Island, the Sub-Antarctic Islands and Antarctica, as well as in the South Pacific.

Our research has a strong emphasis on providing science to support management to ensure the future sustainability of our marine ecosystems.

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bluecod fish and kina under water image 1x

Researchers     

Publications for the above researchers can be found at the bottom of their academic profile page.


Research projects      

  • Bacterioplankton carbon cycling along the Subtropical Frontal Zone
  • Biology and ecology of inlet and estuarine macrobenthos
  • Benthic structure and function of the Otago shelf and upper slope
  • Biodiversity and ecosystem functioning
  • Food web structure in Antarctica and sub-Antarctic Islands
  • Conservation of marine resources in Fiordland
  • Nutrient cycling in estuarine and coastal environments
  • Effects of environmental conditions across latitudinal gradients
  • Fisheries ecosystems in coastal kelp forests
  • Spatial management of marine resources, marine reserves, rotating harvest
  • Role of omnivores in kelp forest community structure


Regionally focused research:

Fiordland

Over the last 25 years of research in Fiordland, our work has focused on:

Food web structure and biogeochemical cycling in the New Zealand fjords with emphasis on how terrestrial carbon is made available to marine consumers, the consequences of species loss for food web dynamics and how changes to food web structure influences higher trophic level groups such as rock lobsters, reef fish, sea birds and people.

Ongoing research in Fiordland includes quantifying ecosystem function and food web structure, organic matter burial in fjord sediments, reconstructing historical changes in phytoplankton production and community structure, and understanding degradation pathways of organic matter across environmental gradients.

These studies are supported by environmental chemistry techniques including stable isotope analysis and compound specific analysis of fatty acids, algal pigments and terrestrial biomarkers.

We also carry out studies on population structure and metapopulation dynamics in these environments employing both stable isotopes and trace elemental analysis of otoliths and skeletal material of crustaceans, and in collaboration with geneticists.

These studies have been used to support management decision making in Fiordland leading to the Fiordland Marine Management Act 200, and subsequent analysis of changes in the ecosystem, including key exploited species such as blue cod and rock lobsters.

We have an active programme monitoring biological and physical changes across the region in the new network of marine reserves and marine protected areas to support the adaptive management process.

The University of Otago Department of Marine Science runs a field laboratory at Deep Cove, Doubtful Sound, enabling to us to work there for extended periods.

Sub-Antarctic Islands

Availability of iron to form light-absorbing pigments in phytoplankton limits productivity in the Southern Ocean.

Seabirds such as albatross and penguins receive iron from food webs across vast areas of the Southern Ocean and congregate around the sub-Antarctic islands in huge numbers to breed.

We are using the latest technical advances in tracing sources of carbon and iron in food webs using stable isotopes to resolve nutrient flux and bioaccumulation in these systems and answer this important question:

Does bioaccumulation of iron by seabirds enhance productivity in the vicinity of the sub-Antarctic islands?

We are using the University of Otago’s research vessel, The RV Polaris II, to survey sub-Antarctic waters around the Auckland Islands and the Snares Islands.

We are working in association with Dr Will Rayment, who studies southern right whales at the Auckland Islands

Antarctica

Our research programme in Antarctica has been supported by Antarctica New Zealand, the Antarctic Science Platform and has been conducted out of Scott Base and remote field sites

These projects focus on understanding the role of seasonal sea ice in the nutritional dynamics of the benthic community. In particular we are interested in how the sea ice microbial community is used as a food source for larvae and benthic fauna.

Additionally we are working to understand the role of nutrients that are recycled from higher trophic levels (penguins and seals) in driving productivity within the benthic community under the ice.

We employ oceanographic surveys and ice diving in the field and stable isotope and trace metal chemistry in the lab to study these communities and processes, along a gradient of sea ice seasonal persistence and extent.

Stewart Island

The waters around Stewart Island at Pegasus Inlet, Paterson Inlet and Port Adventure are regions with relatively pristine native forest catchments offering rare control sites in investigations of the effect of catchment on nutrient dynamics and estuarine processes.

Paterson’s Inlet Marine Reserve and Te Whaka ā Te Wera/ Paterson Inlet Mātaitai Reserve are ideal locations for studying kelp forest community structure and dynamics including population structure of pāua, kina (sea urchins) and giant kelp (Macrocystis pyrifera). We have focused on the influence of giant kelp on the distribution of fishes and invertebrates and on material dynamics along productivity gradients.

We have also been involved in monitoring of Paterson Inlet Marine Reserve for the Department of Conservation.

The University of Otago Department of Marine Science runs a field laboratory at Oban, enabling to us to work there for extended periods. We use this facility to support postgraduate and 400 level research students.

Otago Coast – Paua Fisheries Ecosystems

This project works to provide ecological information to complement local knowledge to enable community-based management of coastal fisheries and work within the research group Te Tiaki Mahinga Kai.

Estuaries and Coasts around New Zealand

We investigate the ecological and biogeochemical consequences of nutrient enrichment in estuaries and coasts from intensification of land and marine farming. New Zealand offers an excellent opportunity to study estuarine ecosystems with varying nutrient loads, from pristine systems to estuaries with elevated nutrient concentrations. We quantify spatial and temporal variation in rates of nutrient cycling, growth rates of key organisms, and food web dynamics in estuaries.

We also study trophic linkages and connectivity between estuaries and coastal benthic communities. The findings of this research highlight the importance of integrative ecosystem-based management.

In addition, we are conducting manipulation experiments to understand relationships between biodiversity and the role of key functional groups in influencing ecosystem functions.

South Pacific – Coral Reef Ecosystems

We conduct research in the South Pacific on effects of multiple stressors including elevated nutrients and temperature stress on physiological responses of corals in an era of climate change. A key aspect of this research is quantifying nutrient cycling in the coral holobiont and understanding plant-animal interactions between the symbionts and host cells.

Subtropical Frontal Zone off Otago

The Otago shelf and submarine canyon system is situated where sub-Antarctic and subtropical water meet at the subtropical convergence, a distinct frontal zone with unique physical and biological characteristics.  Researchers from the Department are studying the physical processes that underpin primary productivity and patterns in diversity of the zooplankton and mesopelagic fish communities observed to change markedly at the front.  The region supports abundant fish, sea birds and rare marine mammals. Royal albatross, Shepard’s beaked whales and sperm whales are commonly sighted in the region.

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