palaeolimnology | Ecology of the past

6th Workshop on Non-Pollen Palynomorphs

July 9, 2014
encarnimontoya

OUR POSTER: Non-Pollen Palynomorphs in Ecuador: Starting from scratch

Tallinn University
18-20 June 2014

Last month I had the opportunity of attending the 3-days non-pollen palynomorphs (NPP) workshop that was held at the Tallinn University, Estonia. It was perfectly organised by Tiiu Koff and Egle Avi among other members of the university, as it was a join workshop of Cladocera remains (XII Subfossil Cladocera workshop; 16-18^th June) and NPP (18-20^th June). Unfortunately, I was just present in the NPP workshop, so my comments will be focus on it.

With around 40 participants, we greatly enjoyed the discussions that came up about the state-of-the-art of this broad and interesting proxy and its implications for archaeology, palaeolimnology, and different aspects of ecology like human landscape management, biodiversity and conservation, or community assemblages. Current methodological problems like taxonomy, standardisation of lab techniques, etc., were also debated.

Opening and key lectures were from Bas van Geel and Emilie Gauthier, showing the development of this discipline over the last 40 years, and a great example of multi-proxy project aimed to study the human arrival and impact in Greenland respectively. Besides oral and poster presentations, last day there was a microscope session, very useful for sharing knowledge and uncertainties! In our specific case, Will, Hayley and I contributed with a poster titled “Non-pollen palynomorphs in Ecuador: starting from scratch”.

Personally, among the things I most like from the NPP meetings is the friendly and close environment, where everyone is more than glad to help others, regardless the experience. Following this feeling of small and scattered group of people dealing with the same issues, we used to do a final remark session every workshop raising the advances and inconveniences found so far, updating our NPP papers repository (managed by Antonella Miola), and addressing future directions as a group (for instance, we have now our own project in ResearchGate, thanks to Lyudmila Shumilovskikh!). In this particular workshop, I was very happy when I found out that Tallinn University has a green policy (paper free), and they replaced book abstracts etc., by iPads to follow the workshop schedule.

Although these meetings are normally biannual, next conference location and date is yet to be decided, but we hope to have the chance to join this very friendly and supporting community again. In addition, there will be a NPP session in the next European Palaeobotany and Palynology congress, tobe held in University of Padova (Italy), next August 2014. We encourage people with all kind of experience (or lack of) to attend further events.

Two studentships avaliable

January 9, 2013
WDG

Two NERC algorithm funded PhD studentships are currently available with the PCRG. The projects are focused on understanding past environmental change in west tropical Africa and Amazonian-Andean Ecuador. Both projects will involve field work and build on on-going research within the lab.

Closing date 31/01/2013

One project will work on samples collected during fieldwork in 2012 near Papallacta (Ecuador).

Further project details and how to apply below…
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Sediment sampling on the Andean flank, Ecuador

October 10, 2012
HayleyKeen

One of the key goals of the fieldtrip to Ecuador (August-September) was to sample organic and volcanic (tephra) layers from sedimentary exposures with the aim of obtaining new information about past envrionmental change in the region. Our Ecuadorian collaborator, Dr Patricia Mothes (Instituto Geofisico), had identified four of sites she thought might be useful too us: El Fatima Dique, Mera “2” Dique, El Rosol and Vinillos.

At the Fatima site, near Puyo, a thin organic bed was sampled sandwiched between volcanic ash deposits. Wood macrofossils from this deposit have been dated to the last glacial period.

For further descriptions of what we found and field photos read on…

Fieldwork: Papallacta and Cosanga

September 15, 2012
WDG

The second part of our Ecuadorian expedition took in lakes and sections close to the towns of Papallacta and Cosanga. The variation in climatic conditions was marked as we experienced first hand the transition from freezing fog and driving rain to burning sun and heat within a few tens of kilometers as we travelled from >4000 m down to around 1000 m elevation.

Sampling the sedimentary section at Vinillos was hampered by a tropical downpour. Sediments recovered from here include volcanic ash, mud slide deposits including large wood macrofossils and fine grained organic sediments probably deposited in still water environments.

Preparing to recover a short core from a pond near the antenas at Cujuca. Short cores will be used for Chironomid analysis.

Tomorrow we will attempt to recover short cores from two more lakes. Then our final few days here in Ecuador will be spent visiting partners and packing up.

Response of Chironomids to late Pleistocene and Holocene environmental change in the eastern Bolivian Andes

July 10, 2012
WDG

Williams, J.J., Brooks, S. & Gosling, W.D. (2012) Response of Chironomids to late Pleistocene and Holocene environmental change in the eastern Bolivian Andes Journal of Paleolimnology, 48: 485-501. doi: 10.1007/s10933-012-9626-1.

Numerical Analysis of Biological and Environmental Data

June 8, 2012
lottiemiller

Particpants on the Numerical Analysis course 2012: Lottie Miller, Guiomar Sanchez, Maria Rubio, John Douglass and Sonia Jaehnig (left-right). Photo courtesy of Manuela Milan.

Last month I attended the Numerical Analysis of Biological and Environmental Data course at University College London (UCL) in order to decipher which techniques of multivariate data analysis would be useful to apply to my data from Lake Bosumtwi (Ghana). The course was led by Dr Gavin Simpson (UCL) and Prof. John Birks (University of Bergen), both of whom are well experienced in quantitative palaeoecology.

The course provided an introduction to the methods, guidance as to when to use the techniques and then outlined the assumptions, limitations and strengths of the various methods. The need to fully understand the techniques applied before attempting to critically evaluate the results was also strongly emphasised.

The course consisted of lectures covering measures of dispersion, cluster analysis, dendrograms, regression analysis, tree models, gradient analysis, transfer functions, time series and hypothesis testing. Afternoon practical computer classes involved using R, C2 and CANOCO to implement the various techniques covered in the lectures.

Overall the course was a great introduction to statistical analysis which I would certainly recommend for anybody working with complex and noisy datasets. In the next few days I will be using my newly learnt R skills to run indirect gradient analysis such as PCA, CA, DCA and NMDSCAL to search for environmental gradients within my data.

Numerical Analysis of Biological and Environmental Data training couse is an annual event and was held at UCL, on 14-25th May 2012. For more information about the course see Gavin’s website or read his blog From the bottom of the heap.

The Mighty Midge

May 11, 2012
Fray

Fossil chironomid from the Andes

CHIRONOMIDAE AS A PALAEO-ECOLOGICAL TOOL
Chironomidae is a family of two-winged flies more commonly referred to as non biting midges. This diverse group of insects have been known for a long time to be sensitive environmental indicators. Early research in the field showed that the trophic status of lakes could be classified according to the characteristic chironomid assemblages found within them (Thienemann, 1922). Furthermore the head capsules of the larvae are well preserved within the sedimentary record. As a result palaeolimnological researchers became increasingly interested in the potential for using Chironomids to track the trophic development of a lake through time by examining the changing assemblages within the accumulated sediments. With geographically close lakes displaying significantly different midge faunas the potential for the insects being used as climatic indicators was dismissed and the following hypothesis became established: Chironomid assemblage composition reflects in-lake variables, e.g. lake depth, pH, dissolved oxygen, trophic status and substrate. However work by Walker and Matthews (1989) demonstrated that temperature was by far the most significant variable in controlling the broad scale distribution and abundance of midge fauna.

Walker and Matthews realised the potential for the non biting midge to be used as a palaeoclimatic indicator from two initial observations. Firstly within the fossil records, as climate began warming following the deglaciation of the northern hemisphere, the relative abundance of taxa associated with cold oligotrophic lakes (Heterotrissocladius) abruptly declined. Secondly they noticed the best analogues for late glacial assemblages were found in modern day arctic and alpine settings. Overall Walker and Matthews concluded that the northern limit of temperate taxon was controlled by cold summer air and/or water temperatures. The southern limit of Arctic species was instead driven by cold oxygenated refugia in the profundal zone of deep, temperate lakes. These temperatures were significant with respect to the insect’s life cycles as many species require critical temperature thresholds to complete pupation and emergence stages.

Since the pioneering work of Walker and Matthews (1989) and others the debate linking Chironomids to temperature has raged. Debate has centred upon what controls chironomid distribution and how suitable, if at all, the insects are in the context of palaeoecological studies. Recently Velle et al. (2010) discussed some key factors which must be considered when working on chironomid based temperature resonstructions.

Below I present some of the debate around the midge-environment-temperature debate; focusing on both midge distribution and identification and the potential of this proxy as a indicator of past environmental and climatic change.

Nitrogen isotopes in lake sediments

February 28, 2012
lottiemiller

COMMENT ON THE USE OF NITROGEN ISOTOPES IN PALAEOLIMOLOGICAL STUDIES
As a component of my doctoral research, I am examining nitrogen (N) isotopes within sediments obtained from Lake Bosumtwi (West Africa). Below I review and comment on the key uses and limitations of using N isotopes to interpret past environmental change with particular reference to lake sediments. Discussion is based on the key text by Talbot (2001).

REFERENCE
Talbot, M.R. 2001. Nitrogen isotopes in palaeolimnology. Tracking environmental change using lake sediments. Volume 2. Physical and geochemical methods (ed. by W.M. Last and J.P. Smol), pp. 401-439. Kluwer Academic Press, Dordrecht.

NOTE: This text is avaliable to Open University students as an ebook via the library

Environmental change in the humid tropics and monsoonal regions

January 27, 2012
WDG

JUST PUBLISHED
Bush, M.B. & Gosling, W.D. (2012) Environmental change in the humid tropics and monsoonal regions. The SAGE handbook of environmental change: Volume 2. Human Impacts and Response (ed. by J.A. Matthews, P.J. Bartlein, K.R. Briffa, A.G. Dawson, A. De Vernal, T. Denham, S.C. Fritz and F. Oldfield), pp. 113-140. SAGE, London. ISBN: 978-0-857-02360-5

Biodiversity & Ecosystem Services

January 10, 2012
WDG

PAGES (Past Global Changes)
Focus 4: (Past) Human-Climate-Ecosystem Interaction (PHAROS)
Biodiversity Theme Workshop at the Department of Zoology, University of Oxford (9-11 Jan)

Using fossil records to map potential threats, opportunities and likely future developments for biodiversity and ecosystem services
Organised by: Dr. Elizabeth Jeffers, Dr. Shonil Bhagwat and Prof. Kathy Willis

This small (about 30 attendees) workshop brought together academic researchers mainly working in the field of past environmental change to discuss the use, and potential use, of data sets in understanding the key environmental challenges facing society. The bulk of the discussion took place with reference to ‘ecosystem services’. Three types of ecosystem service were mentioned early on for which it was thought that the fossil record can provide a unique long term perspective (beyond historical records): 1) provisioning services (e.g. food, timber, biofuels), 2) regulating services (e.g. carbon), and 3) cultural services (e.g. national parks, tourism).

Below I will summarize some of the issues discussed. Please note that this does not cover the full range of discussion or all of the many high quality contributions. For further information click here to visit the workshop web page.