Modern and pre-Industrial Age distributions of Cladocera in Italian and Swiss Alpine lakes

Abstract

We compared contemporary and preIndustrial Age (before 1850 AD) fossil assemblages of Cladocera in sediment cores from 25 lakes in the Italian and Swiss Alps to investigate the impact of mounting anthropogenic stresses over the last 150 years on community composition. In addition, we sought relationships between specific species and their environments by measuring nutrients, major ions, pH, alkalinity, conductivity, chlorophyll, and lake and catchment morphological features at the time of core collection for comparison with surface sediment fossil assemblages. The modern (surface sediment) communities of the study lakes consisted mainly of benthic chydorids, primarily Alona affinis, A. quadrangularis, Acroperus harpae, and Chydorus sphaericus-type, with Daphnia as the sole planktonic genus. Principal component analysis (PCA), relating the modern Cladocera assemblages to environmental variables at the time of sampling, indicated that A. affinis and A. quadrangularis are influenced by altitude and dissolved inorganic nitrogen (PCA axis 1) whereas Acroperus harpae and C. sphaericus-type are more influenced by potassium (PCA axis 2). Redundancy analysis, however, identified lake water pH and potassium as the measured variables most impacting modern cladoceran assemblages, and especially the distribution of C. sphaericus-type and A. harpae. Pre-Industrial Age samples contained more Daphnia (longispina-type primarily) than modern samples, and some harbored Eurycercus lamellatus, which has since been extirpated from these lakes. The directional shifts in Cladocera assemblages from the pre-industrial period to the present, illustrated as changes in the sample scores along the PCA axes 1 and 2, were associated with the secondary PCA gradient in almost all lakes, and thus were probably the indirect responses to a cascade of limnological alterations, perhaps initiated by large anthropogenic forcing factors such as atmospheric pollution or fish introductions.

Climate change impacts on zooplankton and benthic communities in Lake Unterer Giglachsee (Niedere Tauern Alps, Austria)

“…In contrast to data on zooplankton from Italian and Swiss Alpine lakes and a lake from the Niedere Tauern Alps where Daphnia has generally declined since pre‐industrial times , the present results showed a slight increase in relative Daphnia abundance towards the present. The Alpine zooplankton turnover has most likely been initiated and driven by altered limnological ranges in water temperature, ice‐cover period, stratification, and primary production.…”

Effects of long term nutrient and climate variability on subfossil Cladocera in a deep, subalpine lake (Lake Garda, northern Italy)

“…However, most of the available information on the ecological preferences of Cladocera with respect to nutrients originate from studies conducted on small alpine lakes (Lotter et al 1997;Bigler et al 2006;Kamenik et al 2007;Nevalainen et al 2011) or central-eastern European lakes (Szeroczyńska 2006;Zawisza and Szeroczyńska 2007;Korponai et al 2011). Beside being less numerous, previous studies on Cladocera ecology in large and deep perialpine lakes mainly focused on individual species or responses to ecological stressors other than TP and climate, or were based on sediment cores collected before the beginning of lake restoration measures (Boucherle and Züllig 1983;Hofmann 1998).…”

“…Cladocera remains are therefore considered to be a good proxy for environmental reconstruction (Frey 1986;Sarmaja-Korjonen 2001;Manca et al 2007;Zawisza and Szeroczyńska 2007;Nevalainen et al 2011;Alric et al 2013). They have been widely used to track historical changes in lake nutrient concentrations, either alone or in combination with other paleolimnological proxies (Jeppesen et al 2001;Davidson et al 2007), pH (Paterson 1994;Jeziorski et al 2008), and also to study historical changes in water levels (Korhola et al 2000(Korhola et al , 2005, submerged macrophyte distributions (Davidson et al 2007) and food webs (Finney et al 2000;Jeppesen et al 2001).…”

“…Several studies on subfossil Cladocera have been conducted in Alpine lakes, including both mountain lakes (Lotter et al 1997;Bigler et al 2006;Kamenik et al 2007;Nevalainen et al 2011) and peri-alpine deep lakes such as Lakes Constance (Hofmann 1998), Geneva, Bourget, Annecy (Alric et al 2013;Perga et al 2015) and Zurich (Boucherle and Züllig 1983). However, of the large and deep lakes south of the Alps, which together account for over 80% of Italy's surface freshwater, only Lake Maggiore has been analyzed for subfossil Cladocera (Manca et al 2007).…”

Trophic interactions among the heterotrophic components of plankton in man-made peat pools

“…pH also influenced the distribution of cladoceran communities. The influence of pH on Cladocera has also been shown in studies in lake ecosystems, with the conclusion that low pH coincides with decreased abundances of these animals (Nilssen and Sandoy, 1990;Kurbatova, 2005;Nevalainen et al, 2011). Cladocera are components of the lowest trophic level in the classical food web and function as intermediaries between the microbial and classical food chains (Agasild et al, 2012).…”