Seasonal and ontogenetic changes of mycosporine-like amino acids in planktonic organisms from an alpine lake

Abstract

We studied the quantitative and qualitative mycosporine-like amino acid (MAA) composition in phytoplankton and the copepod Cyclops abyssorum tatricus from an alpine lake over a 15-month period. Up to eight MAAs were identified in the samples, with shinorine being predominant. The MAAs occurred year round and showed a strong seasonal pattern. Compared with ice-cover periods, concentrations during the summer were on average 3.6 and 3.0 times higher in phytoplankton and C. abyssorum tatricus, respectively. During the summer, the contents of MAAs in phytoplankton decreased with depth, suggesting their photoprotective role. Chlorophyll a-specific concentrations of MAAs in phytoplankton correlated significantly with the incident solar radiation and ultraviolet (UV) water transparency (r 2 # 0.36), however, the strongest relationship was found with water temperature (r 2 5 0.67). In zooplankton, highest contents of MAAs were found in eggs, nauplii, and young copepodids, presumably providing a high level of photoprotection for progeny. Proportions of the dominant MAAs in the copepod showed seasonal and ontogenetic variations, which were consistent with relative changes in the predominant MAA, but not other abundant MAAs, in phytoplankton. Considering a time lag of approximately 1 month between the synthesis and subsequent accumulation of these compounds, MAA concentrations in late copepodid to adult life stages were significantly correlated to those in phytoplankton. Annual patterns in MAAs with high concentrations during periods of elevated environmental stress are consistent with the idea that these compounds play an important role in protecting aquatic organisms against UV damage.

Impact of particulate and dissolved material on light absorption properties in a High-Altitude Lake in Tibet, China

“…Also, these peaks decreased as the water depth increased, indicating a vertical distribution of MAAs. A similar vertical distribution of MAAs was observed in other mountain lakes (Tartarotti & Sommaruga, 2006;Ficek et al, 2013). In a 15-month study of an alpine lake, Tartarotti & Sommaruga (2006) found that during summer the content of MAAs in phytoplankton decreased with depth.…”

“…Due to strong impact from land and human activity, Case 2 water has greater variability spatially and temporarily in optical properties (Stedmon et al, 2000;Babin et al, 2003;Twardowski et al, 2004;Ma et al, 2006). Studies of the optical properties of high mountain lakes (Tartarotti et al, 1999;Laurion et al, 2000;Zhou et al, 2005;Tartarotti & Sommaruga, 2006;Zhang et al, 2009;Zhang et al, 2010;Ficek et al, 2013) have received considerable attention partly because of their harsh environment and partly because remotely located lakes can be considered as sensitive indicators of environmental and climate changes (SommarugaWögrath et al, 1997;Williamson et al, 2008;Adrian et al, 2009). However, such studies have rarely been conducted for the lakes located on the world's highest plateau, and ground-based measurements of optical properties of lake water on the TP are rare.…”

“…6b might be due to absorption by mycosporine-like amino acids (MAAs), which have been found in phytoplankton from several mountain lakes (Tartarotti & Sommaruga, 2006;Ficek et al, 2013). They play a role in protecting alpine aquatic organisms from UV radiation.…”

Temporal changes in the dominance of major planktonic bacterial groups in an alpine lake: discrepancy with their contribution to bacterial production

“…Filters were then stored frozen until extraction (within 4 mo). Extraction and chl a determination were done as described in Tartarotti & Sommaruga (2006). The equation of Lorenzen (1967) was used to calculate the concentration of chl a.…”

Effects of nutrients and dissolved organic matter on the response of phytoplankton to ultraviolet radiation: experimental comparison in spring versus summer

“…As cells are exposed to UVR, they produce more photoprotective compounds, such as MAAs (Karentz et al, 1991, Helbling et al, 1996. Tartarotti and Sommaruga (2006) found MAA concentrations were much higher in the late summer compared to just after ice-out. It is known that marine cryptomonads have a high proportion of UVR absorbing compounds (Jeffrey et al, 1999), so Chroomonas sp.…”