Lifetime Response of Contemporary Versus Resurrected Daphnia galeata Sars (Crustacea, Cladocera) to Cu(II) Chronic Exposure

Abstract

Resurrecting legacy lineages of organisms from sediment cores of known geological age allows us to understand how environmental change can cause selection pressures that constrain the variation of populations over time. We quantified the lifetime tolerance and effects of Cu(II) exposure on Daphnia galeata in a polluted subalpine lake by comparing extant individuals with those resurrected from ephippia extracted from ca. 30-years-old sediments. Laboratory experiments were conducted using two Cu(II) concentrations, 40 and 10 µg L(-1), corresponding to the levels recorded in the lake, during chemical recovery, when Daphnia first re-appeared and succeeded. Contemporary Daphnia were unable to survive after the 10th day at either of the Cu(II) concentrations, and were unable to successfully reproduce. Daphnia cohorts from the past performed better in low Cu(II) concentrations than in copper-free, control conditions. The copper-adapted, tolerant Daphnia strains grew faster under non-toxic conditions, but were unable to survive new pollution events.

Unexpected increases in rotifer resting egg abundances during the period of contamination of Lake Orta

“…Methods of resurrection ecology have been useful for daphniids (Piscia et al, 2015), and this approach could also be useful for future work on rotifers. Further research is needed, however, to address genetic diversity of these important components of the lake biota and to allow for a comparison between sediment-based and water columnbased diversity estimates.…”

Seventy five years of limnology at the Istituto Italiano di Idrobiologia in Pallanza

“…Resurrecting ancestors for transgenerational tests represents a new experimental approach to paleolimnology, answering the vexing question of how to test paleolimnological inferences directly (Kerfoot and Weider, 2004). Indirect estimates of past populations to compare their performance with respect to contemporary ones, under past and present conditions allow for detecting changes in level of tolerance along with, and for identifying mechanisms responsible for the essential ability of species/clones to compete and survive under different perturbations, included heavy metal pollution (Piscia et al, 2014;Frisch et al, 2014).…”

Demographic cost and mechanisms of adaptation to environmental stress in resurrected Daphnia

“…Electrophoretic studies revealed that the population consisted of a single clone of Daphnia obtusa Kurz 1875 (Bachiorri et al, 1991). In 1989, a Daphnia species of the D. longispina group -later identified as Daphnia galeata Sars 1863 (Piscia et al, 2015) -colonized the lake and, as water quality improved rapidly after liming, eventually (in 1996) replaced D. obtusa from the pelagic community (Bonacina and Pasteris, 2001). High sensitivity of D. galeata to acidic conditions likely prevented this species from establishing a viable population in the lake at an earlier stage (Ponti et al, 2010).…”

“…In a recent study on Lake Orta Daphnia, Piscia et al (2015) compared the life histories of contemporary and ca. 25-year old lineages of D. galeata exposed to different levels of copper pollution.…”

“…Specifically, Piscia et al (2015) subjected laboratory-reared offspring from contemporary individuals from the now unpolluted lake and offspring from past, resurrected Daphnia -the latter obtained from ephippia found in sediments deposited during the early phases of lake recovery -to two concentrations of copper, representing early (high pollution) and late (low pollution) phases of lake recovery as well as to current (unpolluted) conditions. By recording life-table data of individually kept Daphnia, Piscia et al (2015) found that the low-copper treatment had no significant effect on survival and reproduction of past Daphnia when compared to unpolluted conditions, whereas high levels of copper delayed the onset of reproduction, reduced the fecundity, and led to smaller offspring compared to both the unpolluted and the low-copper environment. Contemporary individuals, on the other hand, failed to produce viable offspring at elevated copper concentrations.…”