title: Sea ice dynamics drive benthic microbial communities in McMurdo Sound, Antarctica

authors: Currie, Ashleigh Ann

subjects: Science & Technology

abstract: Climate change is driving dramatic variability in sea ice dynamics, a key driver in polar marine ecosystems. Projected changes in Antarctica suggest that regional warming will force dramatic shifts in sea ice thickness and persistence, altering sea ice-associated primary production and deposition to the seafloor. To improve our understanding of the impacts of sea ice change on benthic ecosystems, we directly compared the benthic microbial communities underlying first-year sea ice (FYI) and multi-year sea ice (MYI). Using two tractable coastal habitats in McMurdo Sound, Antarctica, where FYI (Cape Evans) and MYI (New Harbour) prevail, we show that the structure and composition of the benthic microbial communities reflect the legacy of sea ice dynamics. At Cape Evans, an enrichment of known heterotrophic algal polysaccharide degrading taxa (e.g., Flavobacteriaceae, unclassified Gammaproteobacteria, and Rubritaleaceae) and sulfate-reducing bacteria (e.g., Desulfocapsaceae) correlated with comparatively higher chlorophyll a (14.2±0.8μgg−1) and total organic carbon content (0.33%±0.04), reflecting increased productivity and seafloor deposition beneath FYI. Conversely, at New Harbour, an enrichment of known archaeal (e.g., Nitrosopumilaceae) and bacterial (e.g., Woeseiaceae and Nitrospiraceae) chemoautotrophs was common in sediments with considerably lower chlorophyll a (1.0±0.24μgg−1) and total organic carbon content (0.17%±0.01), reflecting restricted productivity beneath MYI. We also report evidence of a submarine discharge of sub-permafrost brine from Taylor Valley into New Harbour. By comparing our two study sites, we show that under current climate-warming scenarios, changes to sea ice productivity and seafloor deposition are likely to initiate major shifts in benthic microbial communities, with heterotrophic organic matter degradation processes becoming increasingly important. This study provides the first assessment of how legacy sea ice conditions influence benthic microbial communities in Antarctica, contributing insight into sea ice–benthic coupling and ecosystem functioning in a polar environment.

text: Sea ice dynamics drive benthic microbial communities in McMurdo Sound, Antarctica Climate change is driving dramatic variability in sea ice dynamics, a key driver in polar marine ecosystems. Projected changes in Antarctica suggest that regional warming will force dramatic shifts in sea ice thickness and persistence, altering sea ice-associated primary production and deposition to the seafloor. To improve our understanding of the impacts of sea ice change on benthic ecosystems, we directly compared the benthic microbial communities underlying first-year sea ice (FYI) and multi-year sea ice (MYI). Using two tractable coastal habitats in McMurdo Sound, Antarctica, where FYI (Cape Evans) and MYI (New Harbour) prevail, we show that the structure and composition of the benthic microbial communities reflect the legacy of sea ice dynamics. At Cape Evans, an enrichment of known heterotrophic algal polysaccharide degrading taxa (e.g., Flavobacteriaceae, unclassified Gammaproteobacteria, and Rubritaleaceae) and sulfate-reducing bacteria (e.g., Desulfocapsaceae) correlated with comparatively higher chlorophyll a (14.2±0.8μgg−1) and total organic carbon content (0.33%±0.04), reflecting increased productivity and seafloor deposition beneath FYI. Conversely, at New Harbour, an enrichment of known archaeal (e.g., Nitrosopumilaceae) and bacterial (e.g., Woeseiaceae and Nitrospiraceae) chemoautotrophs was common in sediments with considerably lower chlorophyll a (1.0±0.24μgg−1) and total organic carbon content (0.17%±0.01), reflecting restricted productivity beneath MYI. We also report evidence of a submarine discharge of sub-permafrost brine from Taylor Valley into New Harbour. By comparing our two study sites, we show that under current climate-warming scenarios, changes to sea ice productivity and seafloor deposition are likely to initiate major shifts in benthic microbial communities, with heterotrophic organic matter degradation processes becoming increasingly important. This study provides the first assessment of how legacy sea ice conditions influence benthic microbial communities in Antarctica, contributing insight into sea ice–benthic coupling and ecosystem functioning in a polar environment.

year: 2021

title: Virtue and self-interest

authors: Hardwicke, Tery Vance

subjects: Egoism

abstract: Why be moral? One possible, and compelling answer is that to act morally is in an agent's self-interest. Such an answer can be either elevationist (broadly speaking the Aristotelian/Platonic approach) where self-interest is elevated to coincide with living the good life, or reductionist where morality is defined as acting in an agent's self-interest.

Elevationist moral theories appear flawed. If you are in possession of information that, if divulged, will bring about the deaths of others then it may be virtuous to stay silent. However, if staying silent results in you being slowly tortured to death in an effort to extract the information then it seems bizarre to suggest that in doing so you are flourishing, happy, or acting out of self-interest.

Reductionist moral theories, acting for the 'good of self' rather than the 'good of others', are widely considered to be the antithesis of morality. Moral philosophers tend to attack such positions claiming that the doctrine of egoism is unworkable. It is commonly claimed that any theory which recommends 'an agent do x if x is in the agent's best interest' is inconsistent, incoherent, or contradictory and fails to meet the basic requirements of a moral theory (notably the requirement of universalisability).

I begin this thesis with an examination of ethical egoism in its most widely known consequentialist form; i.e. an agent ought to act so as to bring about the best consequences for that agent. I examine the major criticisms of this theory and demonstrate that the axioms of egoism can be developed so as to overcome these criticisms. I argue that consequentialist based ethical egoism is coherent, consistent and noncontradictory. However, I go on to argue that while egoism can be formulated in a manner that overcomes all the aforementioned analytic criticisms it is a flawed moral theory in that within certain contexts the action deemed morally correct by egoism is, as a matter of fact, morally pernicious. That a theory contains a flaw is not reason enough to discard the entire theory and I go on to contend that the problem with egoism is the consequentialist approach, not the fact that it is based on self-interest.
In Part 2 of the thesis I abandon the consequentialist approach and examine the possibility of a flourishing-based form of ethical egoism. I further develop the axioms of egoism established in Part 1 through an examination of the concept of flourishing (as commonly associated with virtue ethics). Ultimately I tread a path between the consequentialist and elevationist positions. While I do not elevate self-interest to acting virtuously I do contend that an egoist must adopt certain virtues if that egoist is to have the best possibility to flourish. However, I further contend that an egoist ought to act so as to promote that which the egoist values and that this agent-relative hierarchy of values, which necessarily contains certain virtues, determines the manner in which an egoist ought to act.

text: Virtue and self-interest Why be moral? One possible, and compelling answer is that to act morally is in an agent's self-interest. Such an answer can be either elevationist (broadly speaking the Aristotelian/Platonic approach) where self-interest is elevated to coincide with living the good life, or reductionist where morality is defined as acting in an agent's self-interest.

Elevationist moral theories appear flawed. If you are in possession of information that, if divulged, will bring about the deaths of others then it may be virtuous to stay silent. However, if staying silent results in you being slowly tortured to death in an effort to extract the information then it seems bizarre to suggest that in doing so you are flourishing, happy, or acting out of self-interest.

Reductionist moral theories, acting for the 'good of self' rather than the 'good of others', are widely considered to be the antithesis of morality. Moral philosophers tend to attack such positions claiming that the doctrine of egoism is unworkable. It is commonly claimed that any theory which recommends 'an agent do x if x is in the agent's best interest' is inconsistent, incoherent, or contradictory and fails to meet the basic requirements of a moral theory (notably the requirement of universalisability).

I begin this thesis with an examination of ethical egoism in its most widely known consequentialist form; i.e. an agent ought to act so as to bring about the best consequences for that agent. I examine the major criticisms of this theory and demonstrate that the axioms of egoism can be developed so as to overcome these criticisms. I argue that consequentialist based ethical egoism is coherent, consistent and noncontradictory. However, I go on to argue that while egoism can be formulated in a manner that overcomes all the aforementioned analytic criticisms it is a flawed moral theory in that within certain contexts the action deemed morally correct by egoism is, as a matter of fact, morally pernicious. That a theory contains a flaw is not reason enough to discard the entire theory and I go on to contend that the problem with egoism is the consequentialist approach, not the fact that it is based on self-interest.
In Part 2 of the thesis I abandon the consequentialist approach and examine the possibility of a flourishing-based form of ethical egoism. I further develop the axioms of egoism established in Part 1 through an examination of the concept of flourishing (as commonly associated with virtue ethics). Ultimately I tread a path between the consequentialist and elevationist positions. While I do not elevate self-interest to acting virtuously I do contend that an egoist must adopt certain virtues if that egoist is to have the best possibility to flourish. However, I further contend that an egoist ought to act so as to promote that which the egoist values and that this agent-relative hierarchy of values, which necessarily contains certain virtues, determines the manner in which an egoist ought to act.

year: 2007

title: AMS radiocarbon dating of Rattus Exulans bone from the Kokohuia Site (New Zealand)

authors: Higham, Thomas F.G.

abstract: We AMS radiocarbon dated rat bones (Pacific rat (Rattus exulans)) from the archaeological site of Kokohuia, in Northland, New Zealand. An initial series were up to 1200 years too old, but the reason for the offset remained obscure. We considered dietary foodwebs, post-depositional contamination and taphonomy as possible explanations. None provided robust answers. Finally, we identified a laboratory-related error, in which a small amount of old carbon derived from humectants (glycerin) used to moisten ultrafilters prior to the extraction of bone collagen, had become incorporated in the dated collagen. The glycerin humectant was present in amounts averaging 30-40 mg C per ultrafilter, which ordinarily is too small to significantly affect single dates obtained on bone collagen, but was significant in the case of small rat bones. Redating of bones from identical contexts produced a series of results which were within agreement with the age of the site as determined from other materials, including short-lived identified charcoal, and marine and estuarine shell. These results sound a warning for dating very small bone samples, and emphasise the need to consider all possible contaminants derived from laboratory preparation and chemical processing background. In addition, it emphasises the requirement for utilising standard samples of identical type (eg, bone, charcoal, wood etc) which range from young (1-2 half-lives) to background in age, as well as low and high sample mass, as QA laboratory checks on reproducibility (Bronk Ramsey et al., in press).

text: AMS radiocarbon dating of Rattus Exulans bone from the Kokohuia Site (New Zealand) We AMS radiocarbon dated rat bones (Pacific rat (Rattus exulans)) from the archaeological site of Kokohuia, in Northland, New Zealand. An initial series were up to 1200 years too old, but the reason for the offset remained obscure. We considered dietary foodwebs, post-depositional contamination and taphonomy as possible explanations. None provided robust answers. Finally, we identified a laboratory-related error, in which a small amount of old carbon derived from humectants (glycerin) used to moisten ultrafilters prior to the extraction of bone collagen, had become incorporated in the dated collagen. The glycerin humectant was present in amounts averaging 30-40 mg C per ultrafilter, which ordinarily is too small to significantly affect single dates obtained on bone collagen, but was significant in the case of small rat bones. Redating of bones from identical contexts produced a series of results which were within agreement with the age of the site as determined from other materials, including short-lived identified charcoal, and marine and estuarine shell. These results sound a warning for dating very small bone samples, and emphasise the need to consider all possible contaminants derived from laboratory preparation and chemical processing background. In addition, it emphasises the requirement for utilising standard samples of identical type (eg, bone, charcoal, wood etc) which range from young (1-2 half-lives) to background in age, as well as low and high sample mass, as QA laboratory checks on reproducibility (Bronk Ramsey et al., in press).

year: 2004