Seasonal and interannual variability in the taxonomic composition and production dynamics of phytoplankton assemblages in Crater Lake, Oregon

Abstract

Taxonomic composition and production dynamics of phytoplankton assemblages in Crater Lake, Oregon, were examined during time periods between 1984 and 2000. The objectives of the study were (1) to investigate spatial and temporal patterns in species composition, chlorophyll concentration, and primary productivity relative to seasonal patterns of water circulation; (2) to explore relationships between water column chemistry and the taxonomic composition of the phytoplankton; and (3) to determine effects of primary and secondary consumers on the phytoplankton assemblage. An analysis of 690 samples obtained on 50 sampling dates from 14 depths in the water column found a total of 163 phytoplankton taxa, 134 of which were identified to genus and 101 were identified to the species or variety level of classification. Dominant species by density or biovolume included Nitzschia gracilis, Stephanodiscus hantzschii, Ankistrodesmus spiralis, Mougeotia parvula, Dinobryon sertularia, Tribonema affine, Aphanocapsa delicatissima, Synechocystis sp., Gymnodinium inversum, and Peridinium inconspicuum. When the lake was thermally stratified in late summer, some of these species exhibited a stratified vertical distribution in the water column. A cluster analysis of these data also revealed a vertical stratification of the flora from the middle of the summer through the early fall. Multivariate test statistics indicated that there was a significant relationship between the species composition of the phytoplankton and a corresponding set of chemical variables measured for samples from the water column. In this case, concentrations of total phosphorus, ammonia, total Kjeldahl nitrogen, and alkalinity were associated with interannual changes in the flora; whereas pH and concentrations of dissolved oxygen, orthophosphate, nitrate, and silicon were more closely related to spatial variation and thermal stratification. The maximum chlorophyll concentration when the lake was thermally stratified in August and September was usually between depths of 100 m and 120 m. In comparison, the depth of maximum primary production ranged from 60 m to 80 m at this time of year.

Impact of nutrients on photoacclimation of phytoplankton in an oligotrophic lake measured with long-term and high-frequency data: implications for chlorophyll as an estimate of phytoplankton biomass

“…Phytoplankton community composition during summer varied vertically within the water column in both high and low nutrient years similar to previous studies (McIntire et al, 2007). Overall, the epilimnion (above & 20 m) was dominated by diatoms and dinoflagellates, whereas deeper depths had higher diversity (Fig.…”

“…Boss et al (2007) demonstrated that Fchl and Chl-a were highly correlated in Crater Lake, with the exception of reductions in near-surface values during daytime due to non-photochemical quenching. Laboratory Chl-a samples were determined from 17 depths (0-300 m) via extraction using 0.45 lm filters with acetone and a Turner designs Model 10 fluorometer (McIntire et al, 2007). Net primary productivity was estimated at 13 depths (0-180 m), using the carbon-14 light-dark bottle method with a 4 h midday incubation time, 0.45 lm filters, and counted in a Beckman Liquid Scintillation Counter (McIntire et al, 2007).…”

“…Laboratory Chl-a samples were determined from 17 depths (0-300 m) via extraction using 0.45 lm filters with acetone and a Turner designs Model 10 fluorometer (McIntire et al, 2007). Net primary productivity was estimated at 13 depths (0-180 m), using the carbon-14 light-dark bottle method with a 4 h midday incubation time, 0.45 lm filters, and counted in a Beckman Liquid Scintillation Counter (McIntire et al, 2007). Phytoplankton species composition was determined from 17 depths via settling of 500 ml preserved samples and counting/identification with an inverted microscope and 300 cell count minimum.…”

The role of warm, dry summers and variation in snowpack on phytoplankton dynamics in mountain lakes

“…More thoroughly assessing the role of watershed factors in moderating or amplifying lake responses will help us quantify which lakes are more resistant or resilient to environmental change. Our study did not model biological interactions, but future investigators should consider the role of top‐down influences and trophic interactions (McIntire et al 2007, Ellis et al 2011).…”

A comunidade fitoplanctônica no reservatório de Itupararanga (Bacia do Rio Sorocaba, SP)

“…Vários trabalhos descrevem a estrutura da comunidade fitoplanctônica em reservatórios brasileiros. Dentre eles, destacam-se os trabalhos de DOS SANTOS e CALIJURI, 1998;BOUVY et al, 2000;FIGUEREDO e GIANI, 2001;CALIJURI et al, 2002;FALCO e CALIJURI, 2002;RAMIREZ e BICUDO, 2002;TUCCI e SANT'ANNA, 2003;SILVA et al, 2005;TRAIN et al, 2005;MOURA et al, 2007;BORGES et al, 2008;CROSSETTI et al, 2008;DELLAMANO-OLIVEIRA et al, 2008;BECKER et al, 2009; FIGUEREDO e GIANI, 2009 e em outros países os de McINTIRE et al, 2007;SALMASSO e PADISÁK, 2007;CABECINHA et al, 2009; CUNHA e CALIJURI, 2011; CUNHA, 2012.…”