P. Tarrats, M. Rieradevall, N. Prat, M.P. Mata, M. Morellón, J. Vegas, J. Sánchez, B.L. Valero, A. Moreno Geneva 5-10 July 2015 : Global Change in Mountain Lakes

Study and understand the present to explain the past

 “Paleoecological reconstructions using biological registers need a good knowledge of the actual ecology and autoecology of the species” (Birks and Birks, 2004).

 “It is important to combine paleoecological data with those obtained from instrumental series and collected from ecological techniques used in the study of actual ecosystems conditions” (Peng et al., 2011)

 What? . Insecta:Diptera . Aquatics and semi-aquatic . Larvae inhabit lake’s benthos . In paleo: larvae head capsules

 Why? . High taxonomic diversity and abundances . The presence of different species reflects different ecological conditions . (identification):  . Preservation (Paleo): 

Chironomid life cycle and larvae We aim to study and understand the actual Chironomidae community in order to improve the interpretation of the chironomid subfossil record

 To characterize the modern chironomid community of Enol Lake.  To evaluate which factors are responsible of changes in community: . Abundance . Composition Enol Lake

Location North Spain (Asturias) Picos de Europa National Park Origin Glacial Altitude 1070 m asl Max depth 22 m Surface Area 12.2 ha

Location map of Enol Lake Enol Lake

T (ºC) DO (%) 5 10 15 20 25 0 25 50 75 100 125 150 Lake type Warm monomictic 0 0 Trophic state Oligotrophic 2 2 4 4

6 6 Lake water chemistry 8 8

Hard water HCO - & Ca ) (m) 3 10 (m 10

12 12 Depth Alkaline Depth 2- 2- 14 14 Low nutrient NO3 , NO 16 May 16 contents NH4+ &PO 3- May 4 July 18 18 July September 20 20 September November November 22 22

No depth patterns Temperature and DO profiles of 4 samplings (May, July, September and November) of 2013 in Enol Lake. Project CLAM-1 (unpublished data)  8 fieldwork samplings in 2013 and 2014: May, July, September and November.  Depth transect: samples every 2m of depth, 3 replicates  Profundal zone: Ekman grab (15cm2)  Littoral zone: kick-sampling (1m2)

Profile of Enol Lake showing sampling metods and Ekman grab.  A total of 204 samples were analyzed

Samples cleaning Macroinvertebrate Chironomidae Chironomidae and sediment sorting (Family larvae morphotype larvae mounting sieving level) classification and identification

-KOH digestion -Mounting in slides -Identification under a microscope (400x)  A total of 14,248 Chironomidae larvae were identified  26 species, 4 sub-families: . Chironominae ▪ Tribe : 11 species ▪ Tribe Tanytarsini: 4 species . Orthocladiinae: 7 species . Tanypodinae: 3 species . Prodiamesinae: 1 specie  Rare taxa (<2% in at least 2 samples) were removed in the data analysis 16 species

Chironomus plumosus, pagana, Procladius choreus and Paratanytarsus bituberculatus from Enol Lake. Profundal Littoral Environmental variables:

• Temperature • Dissolved Oxygen Species • pH matrix DCA length of gradients <3 • Depth • Chara Redundancy Analysis (RDA)

Are there significant differences between… (ANOSIM Test) •Years  p-value=0.57 Stability of the community • Samplings  p-value=0.26

•Depths  p-value= 0.01 R= 0.6 Chara zone

Profundal RDA Axis Axis 2 RDA zone

Littoral RDA analysis of Enol Lake data. Axis 1 explains the zone 29.9% of species variance and the 65.1 % of species – environment relation variance. Axis 2 explains the 10.3% of species variance and the 22.6% of species- RDA Axis 1 environment relation variance. Chara and Oxygen main drivers

Chara-related taxa

Always high DO values

Littoral taxa and sub-littoral taxa

-Great variability in Chara -High DO values, although less than in Chara-related taxa

Profundal taxa

Always no Chara and low DO  The community is quite stable: there are not significant differences along the year and between years.  Changes in the Chironomidae community composition and abundance are mainly driven by the presence of Chara and changes in the DO content .  This results will allow us to improve the interpretation and inference of the paleo record. ▪ Analyse the recent paleo record (1cm of sediment) at every depth to understand the deposition of the chironomid head capsules. ▪ Analyse two sediment cores . ▪ Apply what we are learning from these studies when interpreting the subfossil record.