Research projects

Some examples of specific stable isotope research that NIWA is currently involved in include the following research projects:

• Antarctic ecology: Antarctic toothfish trophic ecology and migration; Distribution, morphology and ecology of Macrourus whitsoni and M. caml (Gadiformes, Macrouridae) in the Ross Sea region; Diet and trophic niche of Antarctic silverfish (Pleuragramma antarcticum) in the Ross Sea, Antarctica.
• Cetacean studies: Dietary studies reveal that male humpback whales do not just each krill; Population, habitat and prey characteristics of blue whales foraging in the South Taranaki Bight; The influence of fasting and opportunistic feeding on the stable isotope values of baleen whale skin; New insights into the feeding ecology of Hector’s dolphins. (Cephalorhynchus hectori) inferred from stable isotope mixing models; Demography and ecology of southern right whales wintering at Campbell Island, New Zealand.
• Megafaunal ecology: Highly migratory species diet and movement studies.
• Freshwater ecology: Tracing sewage-derived organic matter into a shallow groundwater food-web using stable isotope and fluorescence signatures.
• Marine and freshwater nutrient dynamics: Response of surface nutrient inventories and nitrogen fixation to a tropical cyclone in the South-West Pacific; Regenerated primary production dominates in an upwelling shelf ecosystem, northeast New Zealand;  Sedimentary nitrogen uptake and assimilation in the temperate zooxanthellate sea anemone Anthopleura aureoradiata.Marine and freshwater ecosystem structure.
• Deep sea ecology: High intraspecific variability in the diet of a deep-sea nematode: Stable isotope and fatty acid analyses of Deontostoma tridentum on Chatham Rise, Southwest Pacific.
• Marine hazards: the effects of the Kaikoura earthquake on ecosystem structure in the Kaikoura Canyon.
• Fish studies: Variation in morphology and life history strategy of an exploited sparid fish; Matching and mismatching stable isotope (δ¹³C and δ¹⁵N) ratios in fin and muscle tissue among fish species – a critical review; Effect of ingestion on the stable isotope signature of marine herbivorous fish diets.
• Seabird ecology. e.g. Sex-specific foraging during parental care in a size monomorphic seabird, the Australasian gannet (Morus serrator); Does low seasonality drive reduced duration of migration in temperate brown skuas?; Feeding Ecology of Black Backed Gulls – changes over time; Breeding Mottled Petrel feeding ecology and distributions on Cod Fish Island; Fluttering shearwater diet and movements in Hauraki Gulf; Diving petrel dietary studies; Wintering in the sun: niche partitioning by three non-breeding Pterodroma petrel species in the equatorial Pacific Ocean; Stable isotope signatures delineate the non-breeding distributions of sooty shearwaters Puffinus griseus in the North Pacific Ocean; Higher trophic level prey does not represent a higher quality diet in a threatened seabird: implications for relating population dynamics to diet shifts inferred from stable isotopes; Foraging ecology and choice of feeding habitat in the New Zealand Fairy Tern, Sternula nereis davisae; Contemporary and historical separation of transequatorial migration between two genetically-distinct seabird populations; Foraging ecology of the Cook’s petrel Pterodroma cookii during the austral breeding season: a comparison of its two populations; A stable isotopic investigation into the causes of decline in a sub-Antarctic predator, the rockhopper penguin Eudyptes chryoscome.
• Marine microbial community structure and function
• New Zealand’s ocean carbon cycle model: understanding marine carbon cycling and food-webs to predict climate change effects.
• Terrestrial Ecology: Foliar and soil nitrogen and δ¹⁵N as restoration metrics at Pūtaringamotu Riccarton Bush, Christchurch city; Aborigine-managed forest, savanna and grassland: biome switching in montane eastern Australia.
• Gas Emissions: Mitigation via chemical di-nitrogen formation: Exploring ways to remove nitrogen while bypassing nitrous oxide emission aims to develop cost effective techniques for removing reactive N and reducing N₂O emissions in grazed agricultural systems.
• Climate studies: Reconstructing past variations in precipitation and temperature in New Zealand on decadal to millennial timescales through the analysis of skeletal remains of heads of midge larvae; Climate reconstruction using the New Zealand freshwater bivalve Echyridella menziesii from Lake Rotorua.
• Deep Sea Geochemistry: Isotopic studies of methane seeps – tracing sources of carbon.
• Terrestrial ecology: Feeding ecology of ants.
• Tracking sediment sources: Using fatty acid compound specific isotope analysis.