Chydoid ephippia as indicators of environmental change biostratigraphical evidence from two lakes in southern Finland

Abstract

This study presents a new proxy method for studying past environmental change. The method is based on the relative abundance of ephippia of chydorid Cladocera (Chydoridae). Ephippia are a modification of the carapace that protects the resting eggs against, for example, freezing and desiccation. Holocene records of chydorid ephippia and other gamogenetic remains (male headshields and postabdomens, and headshields of ephippial females) from two lakes in southern Finland (Rutikka and Kaksoislammi) are presented. Results of pollen, diatom and cladoceran analyses from Rutikka Lake are also described. Results from this study suggest that chydorid ephippia are valuable indicators of the environmental stresses occurring in lakes. In particular, ephippia were abundant at both sites during the late Pleistocene/early Holocene transition when the climate was still severe and the open-water season was short. In the later-Holocene record, the relative abundance of the ephippia also reflected the environmental stress during profound changes in predator-prey relationships in Kaksoislammi Lake. In contrast, a change in the relative abundance of ephippia of only one species (Alona affinis) occurred in the late Holocene in Rutikka Lake when prehistoric cultivation took place and affected the water chemistry.

Younger Dryas Cladocera assemblages from two valley mires in central Poland and their potential significance for climate reconstructions

“…Dominik Pawłowski of Cladocera ephippia, based on changes in reproduction and usually dependent on the length of the open-water season, is a very useful technique for reconstructing climate trends (Sarmaja-Korjonen, 2003;Sarmaja-Korjonen & Seppä, 2007;Nevalainen et al, 2011).…”

“…When the Cladocera were counted, chydorid carapaces (representing asexual reproduction) and ephippia (representing sexual reproduction) were also enumerated. The total chydorid ephippia (TCE) was calculated from the sum of chydorid shells and chydorid ephippia (Sarmaja-Korjonen, 2003).…”

The effect of fish stocking on mountain lake plankton communities identified using palaeobiological analyses of bottom sediment cores

“…The most abundant body part was chosen for each species to represent the number of individuals, and the percentages were calculated from the sum of the individuals. The percentages of chydorid and bosminid ephippia were calculated in relation to all individuals of the Chydoridae or Bosminidae, respectively, according to Sarmaja-Korjonen (2003). The cladoceran remains were identified using keys by Flössner (2000), and the nomenclature follows that proposed by Szeroczyńska and Sarmaja-Korjonen (2007).…”

Eemian environmental changes recorded in lake deposits from Rzecino (NW Poland): Cladocera, isotopic and selected geochemical data

“…Another difference is the presence of a high abundance of ephippia in the sediments, which indicates a progressive cooling and reflects the northerly location of this reservoir (closer to the adjacent growing ice sheet) in relation to other researched lakes. This cooling could shorten the summer (growing period) and stimulate a production of resting eggs (Frey 1982;Sarmaja-Korjonen 2003). In addition, compared with other paleolakes e.g., Studzieniec and Solniki (Mirosław-Grabowska and Niska 2007b;Niska 2008) in paleolake Rzecino occurred lower biodiversity of Cladocera species during the existence of the lake.…”

“…The large percentage of resting eggs may be due to a significant shortening of the period of favorable conditions for the development of zooplankton. The resting eggs inside ephippia are preserved throughout the winter (or other unfavorable periods) to enable re-establishment of populations in the following spring when environmental conditions will become favorable (Frey 1982;Sarmaja-Korjonen 2003). The highest values of Cyperaceae and Poaceae and a slight increase in Artemisia and Chenopodiaceae indicate an increase in herbaceous communities in open areas and reflects the progressive deterioration of the climate (Winter and Dobracka 2006;Winter et al 2008).…”