Limnological and nearshore diatom communities of Macquarie Island: proxies of subantarctic climate change?

Macquarie Island offers scientists a unique laboratory for investigating subantarctic climate change. We will establish the biodiversity of microalgal flora (specifically diatoms) within the lakes and lagoons of Macquarie Island and ultimately use the flora of today to investigate changes in fossil microalgal communities of Macquarie Island lake and lagoon ecosystems to better understand past, present and future climate change in the Australian Subantarctic.

Taken from the abstract of the referenced paper: This study is the first established survey of diatom-environment relationships on sub-Antarctic Macquarie Island. Fifty-eight sites in 50 coastal and inland lakes were sampled for benthic diatoms and water chemistry. 208 diatom species from 34 genera were identified. Multivariate analyses indicated that the lakes were distributed along nutrient and conductivity gradients.

Conductivity, pH, phosphate (SRP), functions provide a quantitative basis for palaeolimnological studies of past climate change and human impacts, and can be used to establish baseline conditions for assessing the impacts of recent climate change and the introduction of non-native plants and animals. Statistically robust diatom transfer functions for conductivity, phosphate and silicate were developed, while pH and temperature transfer functions performed less well.

The lower predictive abilities of the pH and temperature transfer functions probably reflect the broad pH tolerance range of diatoms on Macquarie Island and uneven distribution of lakes along the temperature gradient. This study contributes to understanding the current ecological distribution of Macquarie Island diatoms and provides transfer functions that will be applied in studies of diatoms in lake sediment cores to quantitatively reconstruct past environmental changes.