Noah's ark conservation will not preserve threatened ecological communities under climate change

Background: Effective conservation of threatened ecological communities requires knowledge of where climatically suitable habitat is likely to persist into the future. We use the critically endangered Lowland Grassland community of Tasmania, Australia a

Ocean carbon and nitrogen isotopes in CSIRO Mk3L-COAL version 1.0: a tool for palaeoceanographic research

The isotopes of carbon (δ13C) and nitrogen(δ15N) are commonly used proxies for understanding the ocean.When used in tandem, they provide powerful insight into physical andbiogeochemical processes. Here, we detail the implementation ofδ13C and δ15N in the ocean component of anEarth system model. We evaluate our simulated δ13C andδ15N against contemporary measurements, place the model'sperformance alongside other isotope-enabled models and document the responseof δ13C and δ15N to changes in ecosystemfunctioning. The model combines the Commonwealth Scientific and IndustrialResearch Organisation Mark 3L (CSIRO Mk3L) climate system model with theCarbon of the Ocean, Atmosphere and Land (COAL) biogeochemical model. Theoceanic component of CSIRO Mk3L-COAL has a resolution of 1.6∘latitude × 2.8∘ longitude and resolves multimillennialtimescales, running at a rate of ∼400 years per day. We show that thiscoarse-resolution, computationally efficient model adequately reproduceswater column and core-top δ13C and δ15Nmeasurements, making it a useful tool for palaeoceanographic research.Changes to ecosystem function involve varying phytoplankton stoichiometry,varying CaCO3 production based on calcite saturation state andvarying N2 fixation via iron limitation. We find that large changesin CaCO3 production have little effect on δ13C andδ15N, while changes in N2 fixation and phytoplanktonstoichiometry have substantial and complex effects. Interpretations ofpalaeoceanographic records are therefore open to multiple lines ofinterpretation where multiple processes imprint on the isotopic signature,such as in the tropics, where denitrification, N2 fixation andnutrient utilisation influence δ15N. Hence, there issignificant scope for isotope-enabled models to provide more robustinterpretations of the proxy records

Climate projections for ecologists

Climate projections are essential for studying ecological responses to climate change, and their use is now common in ecology. However, the lack of integration between ecology and climate science has restricted understanding of the available climate dat

Bottom water properties observed during Nathanial B. Palmer cruises NBP00-08 and NBP04-08 to the Southern Ocean

We report on observations of dense shelf water overflows and Antarctic Bottom Water (AABW) formation along the continental margin of the Adelie and George V Land coast between 140°E and 149°E. Vertical sections and bottom layer water mass properties sampled during two RVIB Nathaniel B Palmer hydrographic surveys (NBP00-08, December 2000/January 2001 and NBP04-08, October 2004) describe the spreading of cold, dense shelf water on the continental slope and rise from two independent source regions. The primary source region is the Adelie Depression, exporting high-salinity dense shelf water through the Adelie Sill at 143°E. An additional eastern source region of lower-salinity dense shelf water from the Mertz Depression is identified for the first time from bottom layer properties northwest of the Mertz Sill and Mertz Bank (146°E-148°E) that extend as far as the Buffon Channel (144.75°E) in summer. Regional analysis of satellite-derived ice production estimates over the entire region from 1992 to 2005 suggests that up to 40% of the total ice production for the region occurs over the Mertz Depression and therefore this area is likely to make a significant contribution to the total dense shelf water export. Concurrent time series from bottom-mounted Microcats and ADCP instruments from the Mertz Polynya Experiment (April 1998 to May 1999) near the Adelie Sill and on the upper continental slope (1150 m) and lower continental rise (3250 m) to the north describe the seasonal variability in downslope events and their interaction with the ambient water masses. The critical density for shelf water to produce AABW is examined and found to be 27.85 kg/m**3 from the Adelie Depression and as low as 27.80 kg/m**3 from the Mertz Depression. This study suggests previous dense shelf water export estimates based on the flow through the Adelie Sill alone are conservative and that other regions around East Antarctica with similar ice production to the Mertz Depression could be contributing to the total AABW in the Australian-Antarctic Basin