Influence of lake trophic conditions on the dominant mixotrophic algal assemblages

Saad, Juan Francisco; Unrein, Fernando; Tribelli, Paula María; López, Nancy I.; Izaguirre, Irina

doi:10.1093/plankt/fbw029

Cited by 47 publications

(36 citation statements)

References 56 publications

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“…However, the behavior of mixotrophs varies between species (Mitra et al 2016, Saad et al 2016, and mixotrophs are typically abundant in both clear and humic unproductive lake ecosystems since phagotrophy serves both as an important strategy for receiving limiting inorganic nutrients for photosynthetic growth when nutrient concentrations are low, as for retrieving energy (carbon) to sustain growth and survival when light conditions are poor (Jones 2000). This observation disagrees with former studies from the same area where mixotrophic abundance increased with lake DOC concentration and increased bacterial prey availability .…”

Section: Phytoplankton Along the Doc Gradientmentioning

confidence: 75%

Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon

Deininger

Faithfull

Bergström

2017

Ecology

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Global change has increased inorganic nitrogen (N) and dissolved organic carbon (DOC; i.e., "browning") inputs to northern hemisphere boreal lakes. However, we do not know how phytoplankton in nutrient poor lake ecosystems of different DOC concentration respond to increased N availability. Here, we monitored changes in phytoplankton production, biomass and community composition in response to whole lake inorganic N fertilization in six boreal unproductive Swedish lakes divided into three lake pairs (control, N enriched) at three DOC levels (low, medium, high), with one reference year (2011) and 2 impact yr (2012, 2013). We found that phytoplankton biomass and production decreased with DOC concentration before N fertilization. Further, phytoplankton community composition also differed with respect to DOC, with a dominance of non-flagellated autotrophs at low DOC towards an increasing dominance of flagellated autotrophs with increased lake DOC concentration. The N fertilization increased phytoplankton biomass and production in all lakes, but did not affect phytoplankton community composition. However, the net response in biomass and production to N fertilization declined with increasing DOC, implying that the lake DOC concentration is critical in order to infer phytoplankton responses to N fertilization, and that the system switches from being primarily nutrient limited to becoming increasingly light limited with increased DOC concentration. In conclusion, our results show that browning will reduce phytoplankton production and biomass and influence phytoplankton community composition, whereas increased inorganic N loadings from deposition, forestry or other land use will primarily enhance phytoplankton biomass and production. Together, any change in the landscape that enhances inorganic N availability will increase phytoplankton production and biomass, but the positive effects of N will be much weaker or even neutralized in browner lakes as caused by light limitation.

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Section: Phytoplankton Along the Doc Gradientmentioning

confidence: 75%

Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon

Deininger

Faithfull

Bergström

2017

Ecology

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“…In addition, Breck () and Magnhagen and Heibo () argue that body shape and mouth size are among the most important determining factors in the diet and foraging capacity of fish. The larger eyes in individuals from LN are likely to be an adaptation to a reduction in light penetration, because LN is a humic lagoon and the penetration of light is usually medium (vertical photosynthetically active radiation extinction coefficient ranges between 0.8 and 2.8 m −1 ; Saad et al ., ) and lower than that in AN (0.75 m −1 ; Rojo, et al , under review).…”

Section: Discussionmentioning

confidence: 95%

Phenotypic and genetic differentiation between diadromous and landlocked puyen Galaxias maculatus

Rojo

Fernández

Figueroa

et al. 2020

Journal of Fish Biology

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This study reports the phenotypic and genetic differences between individuals of puyen Galaxias maculatus from two sites in the same river basin in Tierra del Fuego National Park, southern South America. Individuals from the two sampling sites presented morphometric and genetic differences. The morphometric differences indicated that individuals from Laguna Negra (LN) were short and more robust and had large eyes, whereas those from Arroyo Negro (AN) were thin and elongated and had small eyes. Genetic differences showed that AN individuals had a greater genetic structuration and an older demographic history than LN individuals. The results of this study affirmed that the individuals from the two sampling sites belong to different populations with a high degree of isolation. The demographic history could indicate that the individuals of G. maculatus which migrated to northern areas during the last glaciation settled in the Beagle Channel after its formation. The LN population could have originated after the retreat of the glaciers, migrating from AN.

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“…Both the high total phosphorus concentrations during this time and the occurrence of cyanobacterial blooms are in line with earlier reports from Lake Krankesjön (Hargeby et al ; Zhang et al ) and represent a temporal pattern more frequently observed in shallow lakes (Søndergaard et al ), but are not typically considered favorable conditions for mixotrophs. Nevertheless, Cryptomonas also showed relatively higher importance in more eutrophic lakes in South America (Saad et al ) indicating that nutrient limitation is not necessarily the major driver for phagotrophy in this species.…”

Section: Discussionmentioning

confidence: 99%

Primary producers or consumers? Increasing phytoplankton bacterivory along a gradient of lake warming and browning

Wilken

Soares

Urrutia‐Cordero

et al. 2017

Limnology & Oceanography

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Eukaryotic phytoplankton form the basis of aquatic food webs and play a key role in the global carbon cycle. Many of these evolutionarily diverse microalgae are also capable of feeding on other microbes, and hence simultaneously act both as primary producers and consumers. The net ecosystem impact of such mixotrophs depends on their nutritional strategy which is likely to alter with environmental change. Many temperate lakes are currently warming at unprecedented rates and are simultaneously increasing in water color (browning) due to increased run‐off of humic substances. We hypothesized that the resulting reduction in light intensity and increased bacterial abundances would favor mixotrophic phytoplankton over obligate autotrophs, while higher temperatures might boost their rates of bacterivory. We tested these hypotheses in a mesocosm experiment simulating a gradient of increasing temperature and water color in temperate shallow lakes as expected to occur over the coming century. Mixotrophs showed a faster increase in abundance under the climate change scenario during spring, when they dominated the phytoplankton community. Furthermore, both bacterial abundances and rates of phytoplankton bacterivory increased under future climate conditions. Bacterivory contributed significantly to phytoplankton resource acquisition under future climate conditions, while remaining negligible throughout most of the season in treatments resembling today's conditions. Hence, to our knowledge, we here provide the first evidence for an increasing importance of bacterivory by phytoplankton in future temperate shallow lakes. Such a change in phytoplankton nutritional strategies will likely impact biogeochemical cycles and highlights the need to conceptually integrate mixotrophy into current ecosystem models.

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Influence of lake trophic conditions on the dominant mixotrophic algal assemblages

Cited by 47 publications

References 56 publications

Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon

Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon

Phenotypic and genetic differentiation between diadromous and landlocked puyen Galaxias maculatus

Primary producers or consumers? Increasing phytoplankton bacterivory along a gradient of lake warming and browning

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