Biomass and species structure of the phytoplankton of an high mountain lake (Lake Paione Superiore, Central Alps, Italy)

Abstract

In the framework of the EU MOLAR Project on “Measuring and modelling the dynamic response of remote mountain lake ecosystems to environmental change” a three whole-year study (1996-1998) on the composition and dynamics of phytoplankton community of the high mountain lake, acid sensitive Lago Paione Superiore (LPS) was carried out. The data were analyzed and compared with those gathered during the years 1991-1993. The phytoplankton was made up by nanoplanktonic unicellular algae, the only exception being the colonial Dinobryon sertularia. Just four species, belonging to Chrysophyceae (Chromulina sp., Dinobryon sertularia and Mallomonas alveolata) and to Dinophyceae (Gymnodinium sp.) were important as biomass and density, and they were always present throughout the year. The prevalence of potentially mixotrophic species suggests an adaptive strategy to the low environmental concentrations of inorganic carbon and phosphorus. The seasonal variations of the total biomass were similar to those observed in the previous years. The total number of species has increased; this could be related with the recent increase of the pH and of the alkalinity

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“…Mixotrophic property of Dinobryon provides important advantages when nutrients are limited (Gaedke, 1998;Kümmerlin, 1998). Similar findings are reported some investigations (Pugnetti and Bettinetti, 1999).…”

Phytoplankton of a mountain lake (L’adové pleso, the Tatra Mountains, Slovakia): Seasonal development and first indications of a response to decreased acid deposition

“…Species composition, seasonal development and vertical distribution of phytoplankton The phytoplankton of Ľadové pleso is composed of a low number of species with the predominance of nanoplank- tonic flagellates, as is characteristic for oligotropic high mountain lakes (Lukavský, 1994;Pugnetti & Bettinetti, 1999). Cells of Plagioselmis (formely Rhodomonas) in Ľadové pleso were lacking sharp hyaline tails, so they could be unambiguously determined as Plagioselmis lacustris (Pascher et Ruttner) Javornický (Javornický, 2003).…”

“…The lack of light during the ice cover period is probably the main reason why the maximum of phytoplankton is associated with ice free period in the most intensively studied remote mountain lakes in Europe . A contrasting pattern with phytoplankton maximum under the ice cover of maximum thickness was observed in the high mountain lake Paione Superiore, suggesting their possible shift to heterotrophic metabolism (Pugnetti & Bettinetti, 1999). In Ľadové pleso, such a shift did not occur, and bacteria, heterotrophic nanoflagellates and ciliates formed the microbial assemblage during most of the winter cover period (Nedbalová et al, unpubl.…”

“…The genus Ochromonas is known to be potentially mixotrophic, and this strategy is optimal in oligotrophic conditions (Isaksson, 1998). Mixotrophic species therefore often prevail in mountain lakes (e.g., Pugnetti & Bettinetti, 1999). Mallomonas akrokomos has been reported from both oligotrophic and eutrophic waters, predominantly in winter (Starmach, 1985).…”

Phytoplankton composition and functional groups in a tropical humic coastal lagoon, Brazil

“…Dinobryon sertularia is known to be potentially mixotrophic, showing facultative bacterial feeding (Jones & Rees 1994;Pugnetti & Bettinetti 1999) and Gonyostomum semen has the facultative capacity of heterotrophy by osmotrophy (Eloranta & Järvinen 1989). Indeed, many phytoplankton species, like Cryptomonas spp., can take up dissolved organic carbon or, under inorganic nutrient deficiency, can use dissolved amino acids or other organic sources of (Schoonhoven 2000).…”