In the water

The term is drawing to an end meaning that deadlines are looming. One such deadline that I am working towards at the moment is that of my independent study project. In this project I am investigating and evaluating a range of salinity reconstructions given by numerous proxies taken from a lake sediment core. This means that right now my life involves a lot of ‘palaeo[insert suffix here]’... I have gathered that you can affix pretty much anything on the end of ‘palaeo’ in order to study and make inferences about the past.

However, one such palaeo-combination that I only recently came across was ‘palaeobiodiversity’. I first encountered this paleo- in a paper by Adrian et al.(2009) in which the authors analyse the potential for lakes to act as ‘sentinels’ for climate change. The paper reports that the sensitivity of lakes to climate is well documented and that numerous studies have demonstrated that the physical, chemical, and biological lake properties respond rapidly to climate-related changes (ACIA, 2004). Other authors have suggested that what makes lakes so good at monitoring and recording the effects of climate change, is their high sensitivity to environmental changes as well as the fact that they conveniently integrate changes in the surrounding landscape and atmosphere (Carpenter et al., 2007).

Anyway, in the context of salinity variations in lake water I am afraid I hadn’t given much thought to how palaeolimnology (that’s the reconstruction of past lake environments) could be useful for studying biodiversity. So when I was introduced to palaeobiodiversity in that paper I thought that it would be interesting to learn more about this palaeo- (I’ll stop saying palaeo now, it gets annoying).

Irene Gregory-Eaves and Beatrix E. Beisner give a particularly useful contribution to the study of freshwater biology in their paper ‘Palaeolimnological insights for biodiversity science: an emerging field’. In this paper, the authors argue that palaeolimnology offers unique insights into biodiversity science, and the article highlights both its potential and limitation in providing further understanding of biodiversity dynamics.

What role will palaeolimnology play in the future of biodiversity science?

They write this article in the context of a growing need for scientists and policy makers to understand, predict and manage the consequences of rapid global declines in biodiversity (MillenniumAssessment, 2005). It could be argued that one of the greatest tools for prediction is the past, and I suppose that past trends are the underlying principle behind those fancy climate models developed by the likes of the IPCC (although I don’t know much about models and to be honest I don’t have much of a desire to venture into that section of the library so don’t quote me on this). With this in mind, as well as the fact that lakes make such good sentinels of climate change (Adrian et al.,2009), it makes perfect sense to me that palaeolimnology is used to understand and predict changes in global biodiversity.

As I said, the authors evaluate the role of palaeolimnology in biodiversity science. Palaeolimnology allows the researcher to focus on a single ecosystem, studying the way it changes over time (Gregory-Eaves and Beisner, 2011). This is a key advantage to anyone wishing to infer past changes in biodiversity in a particular area. Another benefit of using palaeolimnology to study biodiversity is the sheer timescale that can be studied. Investigators are able to quantify community responses to environmental changes over centuries, and even millennia! Clearly this would not be achieved by conducting any field-based survey typical of studies of biodiversity.

However, as is usually the case, for every benefit there is a limitation. Not all organisms preserve in sediments meaning that it is often difficult for investigators to find an identifiable remain to record. This is especially problematic for organisms that produce siliceous microfossils (e.g. diatoms) in lakes that are poor in silicate or are very alkaline (Stoermer et al.,  1985).

 

Diatom preservation is not as good in lakes that are poor in silicate

The application of palaeolimnological methods to the field of biodiversity science is a relatively new thing. However initial studies suggest that there is perhaps an exciting future to be had. For example, several studies are beginning to provide an insight into the drivers of community assembly and recovery. In this respect it seems likely that we’ll be seeing a lot more of palaeolimnology in biodiversity in the future!