Phytoplankton absorption spectra along the water column in deep North Patagonian Andean lakes (Argentina)

Abstract

During a summer period we studied the vertical variation of in vivo and chlorophyll a specific phytoplankton absorption spectra in relation to the underwater light climate of ten deep North Patagonian Andean lakes of Argentina. The lakes were thermally stratified, and the underwater light climate was characterized by extended euphotic zones which included highly illuminated epilimnetic layers (both UVR and PAR) and metalimnia exposed to dim blue-green light. Most of the lakes presented the development of Deep Chlorophyll Maxima (DCM) at the metalimnetic layers, near 1% of surface PAR irradiance. Analyzing the fourth-derivative plots of in vivo phytoplankton absorption spectra [d IV a ph (l)], we were able to identify several maxima absorption values attributed to different pigments. Considering lakes with DCM, a significant positive linear relationship was found between d IV a ph (495-500 nm) normalized by chlorophyll a and downward irradiance. Indeed, a negative significant relationship was found between d IV a ph (495-500 nm) normalized by chlorophyll a and diffuse PAR attenuation coefficients. These results point out an increase in the relative concentration of different carotenoids at surface layers indicating the role of photoprotection of these pigments. On the other hand, significant negative linear relationships were found between fourth-derivative spectra normalized by chlorophyll a at 650, 590-595, 560-565 and 520-525 nm and downward irradiance. These results indicated an increase in the relative concentration of photosynthetic accessory pigments at deep layers of the euphotic zone. Furthermore, we found a decrease in depth of specific absorption spectra at 440, 670 nm and in the ratio a ph * (440 nm) to a ph * (670 nm). This pattern was associated with the package effect concept. The increase in relative photosynthetic accessory pigment concentrations and the decrease in values of specific absorption spectra at the bottom of the euphotic zone were attributed to changes in phytoplankton communities between surface and deep layers. These outcomes pointed out that the underwater light climate and temperature water structure are, like in marine systems, very important factors governing the distribution of phytoplanktonic organisms. ARTICLE IN PRESSwww.elsevier.de/limno 0075-9511/$ -see front matterIn addition, the possession of specific photosynthetic accessory pigments suggests that dominant species in the DCM are well adapted to these dim blue-green light scenarios.

Vertical distributions of chlorophyll in deep, warm monomictic lakes

“…We observed the DCM depth to track most closely with depths where the irradiance was 1-2% of surface values, consistent with observations for shallower dimictic lakes (Fee, 1976;Williamson et al, 1996) as well as other monomictic lakes (Pérez et al, 2007). Isolume values (cf.…”

Isoprenoid and branched GDGT-based proxies for surface sediments from marine, fjord and lake environments in Chile

“…As sea surface temperature (SST) data for the Chilean fjords are scarce, unpublished (punctual CTDconductivity, temperature, depth -data taken during the above expeditions) and few published data from austral winter and spring (Gonzalez et al, 2010(Gonzalez et al, , 2011Palma and Silva, 2004) (New et al, 2002; data available at the IWMI on-line climate summary service portal; http://www.iwmi.cgiar.org/). Mean annual lake surface temperature values were taken from the literature whenever possible (Ariztegui et al, 1997;Parra et al, 2003;Gilli et al, 2005;Pérez et al, 2007;Moy et al, 2011). As both mean annual air and lake surface temperature are similar to each other (Table 3), mean annual air temperature (MAAT) values were used for the lakes when surface water temperature values were not available.…”

The water chemistry of some shallow lakes in Northern Patagonia and their nitrogen status in comparison with remote lakes in different regions of the globe

“…Balseiro and Modenutti have a large record of limnological studies in North Patagonia, ranging from food web dynamics (e.g., Balseiro et al 1997Balseiro et al , 2001Modenutti et al 2003) to photosynthetic activity (Modenutti et al 2004;Perez et al 2007) in the lakes located in the Nahuel Huapi National Park. Morris et al (1995) produced a comparative studies between Patagonian lakes and lakes in various regions of the Northern Hemisphere, considering both chemical charateristics and optical properties of lake water.…”