Seasonality of phytoplankton in northern tundra ponds

Abstract

Thermokarst ponds are the most abundant type of water body in the arctic tundra, with millions occurring in the coastal plains of Alaska, Northwest Territories and Siberia. Because ie covers of at least 2 m in thickness are formed at these latitudes, tundra ponds freeze solid every winter As a result, the growing season is shortened to a range of 60 to 100 days, during which time the photoperio-l is altered to a prolonged light phase. Tundra ponds are generally close to neutral in pH and low in ions, contain dissolved gases near saturation and are nutrient poor. In low arctic ponds there are two phytoplankton biomass and primary production peaks, whereas they may be only one in the high arctic. Nanoplanktonic flagellates of the Chrysophyceae and Cryptophyceae dominate the maxima. The mid-summer decline in phytoplankton in the low arctic can be attributed to a combination of phosphorus limitation and heavy grazing pressure. The cryptomonad Rhodomonas minuta Skuja is one of the most widespread phytoplankters in tundra ponds. Because of the altered photoperiods, many species do not form resting spores prior to ice formation but survive freezing in the vegetative state.

Hydrological Connectivity and Basin Morphometry Influence Seasonal Water-Chemistry Variations in Tundra Ponds of the Northwestern Hudson Bay Lowlands

“…This finding suggests that the changes in basin hydrology are strongly regulated by a common external driver such as seasonal variations in meteorological conditions, rather than differences in the amount of disturbance by LSG populations. In northern landscapes, intense seasonality of meteorological conditions can exert strong influence on hydrology of tundra ponds, and affect seasonal patterns of change in nutrients and aquatic productivity (Sheath, 1986;Lougheed et al, 2011;White et al, 2014). For example in the HBL, snowmelt in spring increases connectivity of ponds with the surrounding catchment, and higher hydrologic inflow increases the transfer of allochthonous materials to ponds (e.g., Macrae et al, 2004;Wolfe et al, 2011;White et al, 2014).…”

Interglacial History of a Palaeo-lake and Regional Environment: A Multi-proxy Study of a Permafrost Deposit from Bol’shoy Lyakhovsky Island, Arctic Siberia

“…Their numbers (1-13 and 15-20, Figure 1) are according to the published dataset Porinchu and Cwynar (2000). As an average maximum icecover thickness of water bodies in the region is about 2 m (e.g., Huh et al 1998), the studied water bodies were split into two types following Sheath (1986): ponds (up to 2 m deep) freezing to the bottom during winter, and lakes (deeper than 2 m deep) with water remaining unfrozen under the ice-cover. Below lakes (i.e., deeper than the maximum ice-cover thickness), the permafrost thaws, and perennial thaw bulbs (taliks) form; below ponds (i.e., shallower than the maximum regional ice-cover thickness), only thin, seasonally thawing and freezing zones occur (Brewer 1958;Dyke 1991).…”

“…Below lakes (i.e., deeper than the maximum ice-cover thickness), the permafrost thaws, and perennial thaw bulbs (taliks) form; below ponds (i.e., shallower than the maximum regional ice-cover thickness), only thin, seasonally thawing and freezing zones occur (Brewer 1958;Dyke 1991). The separation of ponds and lakes based on a ratio of depth to ice-cover thickness as in Sheath (1986) is common in arctic studies (e.g., Rouse et al 1997). Among water bodies from the lower Lena River studied by Porinchu and Cwynar (2000) there are only three with the water depth 1.2 m (ponds 2, 3, and 17) and four with the depth of 1.5-2.0 m (ponds 1, 12, 15, and 18).…”

Distribution and Autecology of Chrysophyte Cysts from High Arctic Svalbard Lakes: Preliminary Evidence of Recent Environmental Change

“…These algae typically dominate the phytoplankton and periphyton of northern regions (Moore 1979;Sheath 1986;Siver 1995;Wilkinson et al 2001). Their success is most likely due to their diverse nutritional strategies and ability to produce resistant siliceous resting stages, termed stomatocysts.…”