Dead heads

July 30, 2013

DeadHeads12th International Workshop on Subfossils Chironomids
10-13th June, New Forest, UK

Last month Frazer and Encarni attended the 3-days “dead heads” workshop that was held at the Beaulieu Hotel , in the New Forest National Park (UK). It was perfectly organised by Pete Langdon and Steve Brooks,  and was a great opportunity for both of us who are relatively new to the midges’ community. With around 40 participants from Europe, America and Asia, we greatly enjoyed the discussions that came up about the state-of-the-art for this interesting proxy and the implications for palaeoclimatology, palaeolimnology, and different aspects of ecology like conservation, restoration or community assemblages. In addition, useful topics such as current methodological problems with age-depth model uncertainties, the usefulness and limitations of transfer functions, and taxonomy were also debated.

Besides oral and poster presentations, the workshop offered several tutorials during the afternoons, key amoung these were an introduction to R carried out by Richard Telford and Steve Juggins, and taxonomic support for head capsules ID leaded by Steve Brooks and Oliver Heiri.

In our specific case, Frazer contributed with an oral presentation titled Understanding the modern distributions and ecological tolerances of the Neotropical Chironomidae fauna: The potential as a palaeoecological proxy” base on his PhD research. We were both so glad to make contact with other people working in South America, in particular Julieta Massaferro and Alberto Araneda presented very interesting data from Argentina and Chile.

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. We encourage people with all kind of experience (or lack of) to attend any further events.

PCRG March

April 12, 2013

Rachel Gill and Encarni Montoya with sediment cores from Jamaica.

Rachel Gill and Encarni Montoya with sediment cores from Jamaica.

Quick and belated update on activity in March! Not sure where the time is going at the moment…

Early in the month we were delighted to welcome Prof. Jonathan Holmes and Rachel Gill from UCL who came to use our core splitter to open new sediment cores from Wally Wash Pond in Jamaica! A visit from Steve Brooks (Natural History Museum) early in the month to discuss midgy progress with Frazer was great. We are getting ever closer to developing a training data set… Also popping by was ex-PhD student and now Aberystwyth lecturer Joe Williams who we will hopefully be developing some new collaborations with over the summer and fingers crossed mounting an expedition back to Bolivia!

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August 3, 2012


PCRG members taking part in the Milton Keynes NSPCC Half Marathon, 8 July (left to right: Charlotte Miller, Wesley Fraser and William Gosling)

I have been really excited with the increase in the number of posts and various contributions to this blog over the last month or so. So thanks to everyone who has contributed. The excellent content allows me to focus on just a few research and teaching events which have not been previously covered.

1) Welcome to Wesley Fraser who has joined us officilally as a visiting postdoc for a few months. We hope to develop a paper and another grant submission looking at pollen/spore chemistry during this time; for further details see “Do plants wear sunblock” post.

2) Well done to Frazer and Hayley for performing well in their end of year 1 mini-vivas. Both projects are progressing well and we are all looking forward to field work at the end of the month. Hopefully most of the prepartation and equipment are now in place…

3) Potential for more exiting collaborations was also developed at two meetings. The first, at the Natural History Museum and, in conjunction with long term collaborator Steve Brooks was with old friends Mick Frogley (Sussex) and Alex Chepstow-Lusty. Both Mick and Alex taught me when I was at Cambridge and it would be super exiting to develop a new collaboration with them looking at Chironomids in Andean lakes. The second was at the Univesity of Nottingham as I took part in a UK Tropical Peatlands meeting which brought together ecologists and palaeoecologists from Nottingham, Leeds, Leicester and The OU. The aim of the meeting was to coordinate papers and grant applications.

4) At the end of July beginning of August I taught on the “Sedimentary Rocks and Fossils in the field” topic for the new Practical Science, Earth & Environment (SXG288) module which The OU now offers. Longridge Towers School (no children around this time of year) provided the perfect base for investigating the sedimentary geology of the region. The small group of students had the opportunity to make field observations and test hypotheses related to past environmental change. Everyone was very excited to find numerous fossils and interesting sedimentary structres and had fun trying to work out what they all meant! Congratulations to Angela Coe for putting together this great event.

NERC Fellowship success

July 4, 2012

I am delighted to report that Dr Encarnacion Montoya Romo (currently of the Botanical Institute of Barcelona) has been awarded a NERC Fellowship to join the PCRG. The project is entitled “Evaluation of tropical forests sensitivity to past climate change” (FORSENS) and will examine environmental change at four study sites from different regions of the Neotropics: 1) Khomer Kotcha (Bolivia; 17oS, 4100 m above sea level [asl]) [1-3], 2) Consuelo (Peru, 13oS; 1400 m asl) [4-5], 3) Banos (Ecuador; 0oS, 4000 m asl), and 4) a new lowland site from Columbia/Ecuador to be collected during field work during the project.

The aim of the project is to explore the spatial and temporal consitance of tropical vegetation response to aridity (mid-Holocene dry period) and warming (last deglaciation). The project will use fossil pollen, chironomids, charcoal, non pollen palynomorphs and organic biomarkersto build up a comprehnsive picture of environmental change. The diversity of the project means we have a number of exciting partners, including: Steve Brooks (Natural History Museum), Prof. Mark Bush (Florida Tech),  Prof. Valenti Rull (Botanical Institute of Barcelona) and the Dr. Pauline Gulliver (NERC radicarbon facility).

The fellowship will commence in October 2012. Further information will appear on is blog and group website soon.

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The Mighty Midge

May 11, 2012

Fossil chironomid from the Andes

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.

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