Phytoplankton in extreme environments: importance and consequences of habitat permanency

Abstract

There is hardly any sunshine exposed surface on this Earth, be it water or terrain, which would not support some biota. Still, many habitats offer harsh conditions requiring specialized physiological adaptations to survive. These environments are referred to as extremes; often inhabited by extremophilic organisms. In this review, characteristic species and assemblage properties of phytoplankton inhabiting extreme environments (especially lakes and pools where planktic life is potentially possible and independently of their origin) in terms of alkalinity, acidity, DOC, salinity, temperature, light and mixing regime will be outlined. Lakes characterized by more than a single extreme are common (e.g. saline + alkaline; acidic + high DOC + high metal content + low light). At the edge of extremes (e.g. pH of 1; salinity over ~ 100–150 g l−1) single species with appropriate physiological adaptation are selected and the phytoplankton is often dominated by a single species (monodominant) setting compositional diversity to zero. Under less extreme conditions permanent equilibria may persist; in many cases over several years in contrast to „average” lakes where equilibria are rare and ephemeral. Food webs depending on „extreme phytoplankton” are often atypical for example because the microbial loop is of prior importance or because birds are top predators.

The Ecophysiological Performance and Traits of Genera within the Stichococcus-like Clade (Trebouxiophyceae) under Matric and Osmotic Stress

“…Terrestrial algae, abundant in both extreme and temperate environments, are exposed to several abiotic stressors related to their habitat outside the aquatic environment such as UV radiation, freezing, and unpredictable water availability, where periods of drought of several weeks or even months punctuated by rains are common [ 1 , 2 , 3 ]. The subsequent success of terrestrial algae is partly due to their ability to withstand the stress of undergoing repeated and extended drying–rewetting cycles [ 4 ].…”

Salt to conserve: a review on the ecology and preservation of hypersaline ecosystems

“…The green unicellular algae Dunaliella salina and D. parva are usually the most frequently observed hypersaline planktonic species, occurring over a wide salt range from 9 to 250 g/l (Esmaeili Dahesht et al ., 2010; Oren, 2020). Interestingly, eco‐physiological experiments showed that Dunaliella growth optima are lower (up to 90–150 g/l) than the salinity range of their occurrence in nature, indicating plastic responses to changes in salinity levels (Padisák & Naselli‐Flores, 2021) and also potentially due to relaxation of trophic pressures as has been suggested for invertebrates (Arribas et al ., 2019). As a result, a wide spectrum of abundances of Dunaliella were recorded across hypersaline waters in different regions: up to 1 × 10 10 cells/m 3 in Mexican saltern ponds (Olmos et al ., 2009), 5 × 10 9 cells/m 3 in Greek salterns (Dolapsakis et al ., 2005), 4 × 10 10 cells/m 3 in the Dead Sea (Oren et al ., 1995), 7 × 10 7 cells/m 3 at Lake Tyrell (Australia) (Heidelberg et al ., 2013) and up to more than 50 × 10 7 cells/m 3 in Crimean saline lakes (Senicheva et al ., 2008).…”

Draft Genome Sequence of Limnospira sp. Strain BM01, Isolated from a Hypersaline Lake of the Momela Ecosystem in Tanzania

“…Arthrospira and Limnospira species are well known for their applications ranging from food supplements to industrial polymers ( 2 – 4 ). The East African Rift Valley Region contains a number of saline lakes that are among the most productive ecosystems in the world ( 5 , 6 ), albeit with very few studies being done there ( 6 , 7 ). As a part of our investigations on identifying the genomes of potentially industrial halophiles constituting part of the Big Momela microbiome, we report here the first draft genome sequence of a Limnospira species from that ecosystem.…”