Remarkable Salinity Tolerance of Seven Species of Naked Amoebae (gymnamoebae)

Abstract

The salinity tolerance of naked amoebae collected from sites ranging from ca. 0& to 160& were compared in laboratory experiments. Amoebae were collected from hypersaline ponds around the perimeter of the Salton Sea, California, where salinities averaged 160&, and directly from the shoreline waters of the Sea where salinities were generally between 44 and 48&. Naked amoebae were also collected from the intertidal zone of a Florida beach, a habitat subject (on occasion) to salinity fluctuations within the range 6-85&. From these combined sites, 6 clones of amoebae were isolated for salinity tolerance experiments (2 marine beach isolates, 2 Salton Sea isolates, and 2 hypersaline pond isolates). A seventh clone, Acanthamoeba polyphaga, a common freshwater/soil amoeba, was obtained from a Culture Collection. Laboratory experiments compared the effects of gradually changing culture salinity versus no salinity acclimatization. Growth rate and culture yield were used as indices of effect. Generally, amoebae were tolerant over a wide range of salinity conditions (in terms of growth and yield) and were not markedly influenced by preconditioning to salinity changes throughout the experiments. Overall, the freshwater amoeba Acanthamoeba grew between 0 and 12&, the marine clones grew in the range of 2-120&, and the Salton Sea clones reproduced between 0 and 138 &. The hypersaline clones were the most resilient and grew between 0 and 270& salt. The survival and activity of large populations of naked amoebae in sites subject to salinity fluctuations suggest that they should be considered in future studies to better understand their, as yet, undefined ecological role.

Characterization of Selenaion koniopes n. gen., n. sp., an Amoeba that Represents a New Major Lineage within Heterolobosea, Isolated from the Wieliczka Salt Mine

“…Pernina ‐like amoeba, Vannella septentrionalis , and Vanella mira ) isolated from 44‰ to 48‰ salinity waters of the Salton Sea grew at four or five test salinities between 32‰ and 160‰ salinity (Rogerson and Hauer ). Also, Hauer and Rogerson (2005a) demonstrated that an unidentified limax amoeba (clone 7) isolated from 160‰ salinity water could grow over a much broader salinity range (i.e. 0–272‰), and survived at 292‰ salinity.…”

Recent Advances in Halophilic Protozoa Research

“…In addition to nanoflagellates and ciliates, amoebae were also observed to be grazers (Hamburger ; Hauer and Rogerson ; Hauer et al. ; Post et al.…”

“…; Post et al. ), for example on cyanobacteria in surface mud samples of a salt pond at Eilat, Israel (Hauer and Rogerson ).…”

“…Most “supergroups” of eukaryotes contain one or more types of protozoa that have been reported from hypersaline environments (see tables 1–3 in Hauer and Rogerson and table S1 in Park et al. ).…”

“…It may be (similar to) Euplaesiobystra , but could also represent a different, yet‐to‐be‐sequenced clade of halophiles within Heterolobosea. Probable halophilic heterolobosean amoebae were also collected from hypersaline ponds (16% salt) on the periphery of the Salton Sea, California (Hauer and Rogerson ; Rogerson and Hauer ). Clone 7 (in Hauer and Rogerson ; corresponding to isolate 5 in Rogerson and Hauer ) was a limax amoeba that could form cysts and flagellates, typical features of the Heterolobosea.…”