Quantifying the effects of long term environmental change on World Heritage Macquarie Island - Palaeoecological data from a lake sediment core on Macquarie Island.
Metadata record for data from AAS (ASAC) Project 3117 See the link below for public details on this project. Public Climate change and feral animals are having profound effects on Macquarie Island, threatening its World Heritage values. Through the use of lake sediments and peat deposits we will exa...
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Australian Antarctic Data Centre
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| Online Access: | https://researchdata.ands.org.au/quantifying-effects-long-macquarie-island/698880 https://doi.org/10.4225/15/53223C72B2396 https://data.aad.gov.au/metadata/records/AAS_3117 http://nla.gov.au/nla.party-617536 |
| Summary: | Metadata record for data from AAS (ASAC) Project 3117 See the link below for public details on this project. Public Climate change and feral animals are having profound effects on Macquarie Island, threatening its World Heritage values. Through the use of lake sediments and peat deposits we will examine how the climate has changed in the past, what it was like before feral animals were introduced, and the rate and extent of changes since. This essential information will ensure successful future conservation and restoration and provide a series of measures to assess the recovery of Macquarie Island once the feral animals have been removed. Project Objectives: Macquarie Island is a key site for understanding both Southern Hemisphere and global climate and ecosystem changes as it is one of the few landmasses in the Southern Ocean and one of the few sub-Antarctic islands between 45 degrees and 60 degrees S. Furthermore, it has World Heritage status and is a UNESCO Biosphere Reserve (the only Biosphere Reserve in the sub-Antarctic biogeographic region). Macquarie Island is therefore of considerable global ecological and conservation significance. In order to understand environmental changes occurring on Macquarie Island and to make realistic predictions about future scenarios, it is critical to determine and quantify natural and human-induced causes of change and variability. This can only be achieved by understanding the long term magnitude and direction of natural environmental change, establishing the 'baseline' status of the environment prior to human impacts, and then use this information to separate subsequent natural from human-induced change. This project seeks to: Objective 1 Quantify high resolution long term environmental (climate and ecosystem) change on Macquarie Island over the last 10,000 years in terms of: (i) Temperature and precipitation (using established Macquarie Island diatom transfer functions and in-situ reflectance spectroscopy of lake sediments) (ii) Vegetation assemblages (by pollen, plant macrofossil and DNA analyses of lake and peat sediments) (iii) Abundance, presence and absence of selected fauna, including non-indigenous species (using lacustrine invertebrate microfossils and DNA analyses of lake sediments) (iv) Erosion rates (by measuring sedimentation and accumulation rates in lakes using radioisotope dating). Objective 2 Quantify changes in all of the above variables during the period of human impact (1810-present) to identify ecological anomalies (i.e., changes outside the range of natural variability). In particular, changes attributable to recent shifts in climate and/or the impacts of rabbits will be measured. Objective 3 Integrate changes in each of the above parameters to provide a multiproxy quantification of the effects of long term climate and ecosystem changes on Macquarie Island and an assessment of the impact of feral animals, in particular rabbits. This will provide a framework and set of tools for measuring the extent to which environmental change has occurred due to natural vs. human causes and consequently, the extent to which management targets have been achieved. These tools will consist of straightforward analyses of material incorporated into sediments (e.g., sediment traps) and other records of environmental change (e.g., surface sediments and peat development). The aim of the project was to investigate whether or not a lake sediment core from Macquarie Island could be used to determine the characteristics of the lake prior to the introduction of rabbits and the rates/extent of changes since. This was motivated by wanting to assess the potential of a palaeoecological approach to determine baseline information for assessing the recovery of the island after the eradication of rabbits. A short (50.5 cm) sediment core was collected from Emerald Lake (54 degrees 40'22"S, 158 degrees 52'14"E), northwest Macquarie Island. The core was sectioned at 0.5 cm intervals in the field. Samples were transporting back to the University of Tasmania where the analyses were completed. Analyses undertaken were: 1. Dating the sediment core (210Pb and 14C) 2. Geochemical and physical analyses (water content, organic macrofossils, total carbon, nitrogen and sulphur) 3. Diatom analyses The data provided are raw data for each of the above (in one excel spreadsheet). There are two spreadsheets for the diatom data: 1. Species used in the final publication (species greater than 10% relative abundance). The full species names are provided in this spreadsheet. 2. All species identified, listed using their species codes as designated by K. Saunders. A separate file (AAS3117 Diatom information) is attached that lists all diatom codes and species names. 210Pb dating was undertaken at the Australian Nuclear Science and Technology Organisation. 14C dating was undertaken at ANSTO and Rafter Radiocarbon, New Zealand Geochemical and physical analyses were undertaken at the University of Bern (Institute of Geography) Diatom analyses were undertaken by K. Saunders at the Universities of Bern and Tasmania All analyses were performed using standard procedures. This information was used to qualitatively assess the status of the lake prior to the introduction of rabbits and the rate/extent of changes afterwards. The main findings were (Abstract from Saunders et al. 2014): The introduction and establishment of non-indigenous species through human activities often poses a major threat to natural biodiversity. In many parts of the world management efforts are therefore focused on their eradication. The environment of World Heritage sub-Antarctic Macquarie Island has been severely damaged by non-indigenous species including rabbits, rats and mice, introduced from the late AD 1800s. An extensive eradication program is now underway which aims to remove all rabbits and rodents. To provide a long-term context for assessing the Island's pre-invasion state, invasion impacts, and to provide a baseline for monitoring its recovery, we undertook a palaeoecological study using proxies in a lake sediment core. Sedimentological and diatom analyses revealed an unproductive catchment and lake environment persisted for ca. 7100 years prior to the introduction of the invasive species. After ca. AD 1898, unprecedented and statistically significant environmental changes occurred. Lake sediment accumulation rates increased greater than 100 times due to enhanced catchment inputs and within-lake production. Total carbon and total nitrogen contents of the sediments increased by a factor of four. The diatom flora became dominated by two previously rare species. The results strongly suggest a causal link between the anthropogenic introduction of rabbits and the changes identified in the lake sediments. This study provides an example of how palaeoecology may be used to determine baseline conditions prior to the introduction of non-indigenous species, quantify the timing and extent of changes, and help monitor the recovery of the ecosystem and natural biodiversity following successful non-indigenous species eradication programs. |
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