Life histories and distribution of ostracods with depth in western Lake Geneva (Petit-Lac), Switzerland: a reconnaissance study

Abstract

Because environmental conditions within a given basin are different for each season and at different water depth, knowledge of the life history and depth distribution of target species is important for environmental and palaeoenvironmental interpretations based on ostracod species assemblages and/or the geochemical compositions of their valves. In order to determine the distribution of species with depth as well as the life history of species from Lake Geneva, a oneyear sampling campaign of living ostracods was conducted at five sites (2, 5, 13, 33 and 70 m water depth) on a monthly basis in the Petit-Lac (western basin of Lake Geneva, Switzerland). Based on the results, the different species can be classified into three groups. Littoral taxa are found at 2 and 5 m water depth and include, in decreasing numbers of individuals, Cypridopsis vidua (O.

Neotropical Ostracode Oxygen and Carbon Isotope Signatures - Implications for Calcification Conditions

“…The shells were reacted with 100% phosphoric acid at 70°C in a Kiel II automated reaction system and measured with a Finnigan DELTA plus isotope-ratio mass spectrometer. Reproducibility of replicate analyses for standards (in-house and NBS 19) was better than ±0.08 ‰ for δ 13 C ostracodes and ±0.1 ‰ for δ 18 O ostracodes . All carbonate isotopic values are quoted relative to V-PDB.…”

“…Results of isotopic measurements are given in per mil (‰) with respect to Vienna Standard Mean Ocean Water (V-SMOW) and Vienna Peedee Belemnite (V-PDB), respectively, using the standard delta notation. The analytical precision for stable isotope measurements is ±0.8 ‰ for δD water , ±0.08 ‰ for δ 18 O water and ±0.1 ‰ for δ 13 C DIC values.…”

“…It is known that calcite saturation can be highly variable with diurnal uctuations between saturation and oversaturation in rivers (Neal et al, 2002). Also, changes from undersaturated to saturated conditions are reported on long-term Lakes exhibit a broad range of δ 13 C DIC values, and the variation between lakes is generally larger than seasonal variations within a lake (Bade et al, 2004). It is assumed that biological productivity within a lake is a major control on δ 13 (Herczeg, 1987).…”

“…This requires precise knowledge on the species-speci c life histories including the time of valve calci cation and in-depth knowledge on hydrochemical characteristics. However, even by repeated samplings as usually done (e.g., Heip, 1976;Schweitzer and Lohmann, 1990; Decrouy and Vennemann, 2014), it remains almost impossible to determine the actual time of calci cation in the eld.…”

“…In the present study a highly extended dataset of stable isotope composition of C. ilosvayi (δ 18 O ostracode , δ 13 C ostracode ) and lake water (δD water , δ 18 O water , δ 13 C DIC ) as well as water chemistry and temperature are used for the rst time to verify and extend the above-described approach to the herein measured and collected widespread Neotropical ostracode data set.…”