Abundance and distribution of testate amoebae bearing siliceous plates in freshwater lakes and ponds along the east coast of North America: Importance of water depth and pH

History of the Giraffe Pipe locality inferred from microfossil remains: a thriving freshwater ecosystem near the Arctic Circle during the warm Eocene

“…Second, the significant increase in synurophyte diversity, especially Synura species, is consistent with a small lake or pond with a modest planktic zone (Siver, 1995. Interestingly, Siver and Lott (2012) reported S. uvella Ehrenberg, 1834, emended Korshikov, 1929, the closest modern congener of S. recurvata, and M. insignis growing together in small, mesotrophic, and circumneutral ponds with water depths of 3-5 m. Third, declines in euglyphid testates further signals an increase in water depth (Siver et al, 2020). The decline in Botryococcus, coupled with a thriving chrysophyte community and high abundances of Aulacoseira, also imply moderate nutrient levels (Smittenberg et al, 2005;Nicholls and Wujek, 2015;.…”

“…In addition, water depth and pH often are reported as the most important variables controlling diversity and abundance of testate amoebae in freshwater habitats (Mitchell et al, 1999; Booth, 2002; Patterson et al, 2012; McKeown et al, 2019; Tsyganov et al, 2019; Siver et al, 2020). In a study specifically targeting euglyphid testates, Siver et al (2020) reported the highest concentrations in shallow habitats <1 m in depth that were moderately acidic. Based on the models developed by Siver et al (2020) relating euglyphid abundance to water depth and pH, depths of the Giraffe Pipe waterbody during the Botryococcus Zone were ~1 m, and pH values between 5–6.…”

“…Euglyphid testate amoebae plates accounted for ∼30% of the microfossils in this zone, which is similar to their abundance in the Terminal Lake Zone, but significantly higher than periods in between. Testate amoebae are most common and abundant in shallow lakes and ponds, wetlands, peatlands, and bogs, as well as in wet organic-rich soils and moss beds (Ogden and Hedley, 1980;Escobar et al, 2008;Mitchell et al, 2008;Amesbury et al, 2018;Siver et al, 2020). In addition, water depth and pH often are reported as the most important variables controlling diversity and abundance of testate amoebae in freshwater habitats (Mitchell et al, 1999;Booth, 2002;Patterson et al, 2012;McKeown et al, 2019;Tsyganov et al, 2019;Siver et al, 2020).…”

“…Testate amoebae are most common and abundant in shallow lakes and ponds, wetlands, peatlands, and bogs, as well as in wet organic-rich soils and moss beds (Ogden and Hedley, 1980;Escobar et al, 2008;Mitchell et al, 2008;Amesbury et al, 2018;Siver et al, 2020). In addition, water depth and pH often are reported as the most important variables controlling diversity and abundance of testate amoebae in freshwater habitats (Mitchell et al, 1999;Booth, 2002;Patterson et al, 2012;McKeown et al, 2019;Tsyganov et al, 2019;Siver et al, 2020). In a study specifically targeting euglyphid testates, Siver et al (2020) reported the highest concentrations in shallow habitats <1 m in depth that were moderately acidic.…”

“…In a study specifically targeting euglyphid testates, Siver et al (2020) reported the highest concentrations in shallow habitats <1 m in depth that were moderately acidic. Based on the models developed by Siver et al (2020) relating euglyphid abundance to water depth and pH, depths of the Giraffe Pipe waterbody during the Botryococcus Zone were ∼1 m, and pH values between 5-6. Although diatoms are rare in the Botryococcus Zone, those present were attached forms and this zone lacked planktic diatom species, supporting the hypothesis that the waterbody was shallow.…”