What do Holocene sediments in Petuniabukta, Spitsbergen reveal?

Abstract

Studies of past vegetation from the inner fjords of the Svalbard archipelago have not previously been reported. This study assesses the potential of sediments retrieved from two sites in Petuniabukta, Billefjorden to track vegetation response to Quaternary climate change. The first sediment profile was retrieved from periodic lake on a 4 m a.s.l. marine terrace with a basal radiocarbon dated to 5 080 ± 30 BP, the second was retrieved from a de− pression in wet tundra on a 24 m a.s.l. marine terrace, which upper part was dated to 9 470 ± 30 BP. The study is primarily focused on macro− and micro−fossils. Pollen grains are pres− ent in very low concentrations. Macro−fossils were represented mostly by leafs and buds of Salix species and Dryas octopetala as well as the hybrid Salix herbacea x polaris. Fossil moss remains represent an important part of arctic ecosystems. Tardigrada remains were found in the sediments in high abundance whilst eggs and exuviae of at least six species were identified. The sediments are definitely suitable for the reconstruction of past condi− tions. However, it is necessary to take care not to focus at single type of analysis, as pollen analysis appeared uninformative and more information was obtained from plant macro− fossils (mosses, vascular plants). Little attention has been given to Tardigrada in the past, as they were overlooked and the preservation in sediments is usually very low.

Remains of non-pollen-palynomorphs – tardigrades from Spitsbergen found during pollen analyses

“…These results, with the occurrence of moss dominated vegetation throughout the core, were interpreted as indicating water had been accumulated in situ since the marine terrace uplift, in the mid-Holocene, and then formed into a shallow lake (Bernardová and Košnar 2012). The later occurred in low numbers throughout the core, suggesting possible transport from a local dry site and the former intermittently through the core with an increase in the top section, suggesting local environment change to conditions favouring this species (Bernardová and Košnar 2012). hastatus is a freshwater species and occurred throughout the core.…”

“…Although as a group M. hufelandi taxa are widely distributed and in most environments very frequent, in sediments they were reported as occurring only occasionally (Jankovská and Bliss 1972, 1977; Gómez González and others 2006; Bernardová and Košnar 2012). Ecological requirements for members of this group are unknown and until we have more information, the hufelandi taxa have a rather low value for palaeoecological research…”

“…Cromer and others (2008) suggested that the physicochemical conditions present in high latitude and alpine lakes enable better preservation of tardigrade eggs, or entire exuviae, than the sediment conditions in temperate or tropical lakes. Although it should be noted that standard methods used for pollen analysis (involving harsh chemical treatment of sediments) can destroy delicate microfossils such as tardigrade remains (Cromer and others 2008; Bernardová and Košnar 2012). Results from peat core analysis are rarer (Jankovská 1991; Miller and Heatwole 2003; this study) but possible.…”

“…From the palaeontological point of view, the most important element of tardigrade taxonomy are the eggs (Gómez González and others 2006). Eggs and other tardigrade remains have also been found in lake and bog sediments, from different time periods, on Spitsbergen, Marion Island, in Austria, Czech Republic, Venezuelan Andes and the Antarctic (Hesmer 1929;Brehm and others 1948;Jankovská 1990;Miller and Heatwole 2003;others 2006, 2008;Jankovská 2006;Gibson and others 2007;Montoya and others 2010;Bernardová and Košnar 2012). Tardigrade eggs (and occasionally exuviae or other chitinous body parts) are very resistant and can be fully or partially preserved in sediments for a few thousands years (Gibson and others 2007;Cromer and others 2008).…”

“…However, in the sediments from the boreal zone these objects were more frequent (for example Abisko palsa peatlands) (Jankovská and Kociánová 2010). Eggs and other tardigrade remains have also been found in lake and bog sediments, from different time periods, on Spitsbergen, Marion Island, in Austria, Czech Republic, Venezuelan Andes and the Antarctic (Hesmer 1929; Brehm and others 1948; Jankovská 1990; Miller and Heatwole 2003; Cromer and others 2006, 2008; Jankovská 2006; Gibson and others 2007; Montoya and others 2010; Bernardová and Košnar 2012). Additionally, tardigrade remnants were also discovered in North American amber (Cooper 1964; Bertolani and Grimaldi 2000).…”