2021
Bouma-Gregson, Keith; Power, Mary E.; Furey, Paula C.; Huckins, Casey J.; Vadeboncoeur, Yvonne
Taxon-specific photosynthetic responses of attached algal assemblages to experimental translocation between river habitats Journal Article
In: Freshwater Science, vol. 40, no. 1, 2021.
Abstract | Links | BibTeX | Tags: algae, benthic, Cladophora, cyanobacteria, electron transport rate, flow, Microcoleus, microhabitat, PAM, photosynthesis, temperature
@article{Bouma-Gregson2021,
title = {Taxon-specific photosynthetic responses of attached algal assemblages to experimental translocation between river habitats},
author = {Keith Bouma-Gregson and Mary E. Power and Paula C. Furey and Casey J. Huckins and Yvonne Vadeboncoeur},
url = {https://www.journals.uchicago.edu/doi/pdf/10.1086/713095},
doi = {10.1086/713095},
year = {2021},
date = {2021-02-25},
journal = {Freshwater Science},
volume = {40},
number = {1},
abstract = {Attached algal and cyanobacterial taxa differ in their ability to exploit and tolerate the diversity of flow, irradiance, and temperature regimes typical of a heterogeneous riverscape. Understanding the drivers of the small-scale variation in algal taxonomic composition helps us predict the riverscape-scale effects of altered flow regimes, but microhabitat-scale variation in algal taxonomy complicates the interpretation of ecosystem-scale estimates of biomass or primary production. Using pulse-amplitude modulated (PAM) fluorometry, we performed 2 manipulative field experiments (in 2014 and 2015) to measure photosynthetic responses of algae and cyanobacteria to depth, temperature, and flow modifications. In 2014, we exposed 6 attached algal assemblages common to the South Fork Eel River (California, USA) to a 24-h incubation on either the river bottom (20 cm deep) or floating at the water surface. In 2015, we incubated 3 algal assemblages for 1 wk in either the thalweg or at the river’s edge. For PAM measurements, we developed a novel method (Photosynthesis–Irradiance Periphyton Experimental System [PIPES]) for manipulating attached filamentous algae, a morphology common in aquatic habitats but underrepresented in photosynthesis experiments. To make the PIPES, we sandwiched thin (<1 mm) layers of filamentous attached algae between 2 layers of mesh so that the algae could be isolated and manipulated for repeated PAM measurements. In the 2014 experiment, incubating Cladophora, Rivularia, Microcoleus, and Anabaena at the water surface tended to decrease photosynthetic rates relative to submerged controls, whereas for Nostoc, the photosynthetic rates were higher in floating treatments. In the 2015 experiment, Cladophora and Oedogonium incubated in the warmer, low-flow river margin had persistently lower photosynthesis rates than their counterparts incubated in the thalweg. The PIPES method improves our ability to make PAM measurements on attached algae. PIPES can be used in conjunction with other methods to evaluate taxon-specific responses to environmental conditions and to help us predict how algal assemblages will shift in dominance under different river management regimes.},
keywords = {algae, benthic, Cladophora, cyanobacteria, electron transport rate, flow, Microcoleus, microhabitat, PAM, photosynthesis, temperature},
pubstate = {published},
tppubtype = {article}
}
Attached algal and cyanobacterial taxa differ in their ability to exploit and tolerate the diversity of flow, irradiance, and temperature regimes typical of a heterogeneous riverscape. Understanding the drivers of the small-scale variation in algal taxonomic composition helps us predict the riverscape-scale effects of altered flow regimes, but microhabitat-scale variation in algal taxonomy complicates the interpretation of ecosystem-scale estimates of biomass or primary production. Using pulse-amplitude modulated (PAM) fluorometry, we performed 2 manipulative field experiments (in 2014 and 2015) to measure photosynthetic responses of algae and cyanobacteria to depth, temperature, and flow modifications. In 2014, we exposed 6 attached algal assemblages common to the South Fork Eel River (California, USA) to a 24-h incubation on either the river bottom (20 cm deep) or floating at the water surface. In 2015, we incubated 3 algal assemblages for 1 wk in either the thalweg or at the river’s edge. For PAM measurements, we developed a novel method (Photosynthesis–Irradiance Periphyton Experimental System [PIPES]) for manipulating attached filamentous algae, a morphology common in aquatic habitats but underrepresented in photosynthesis experiments. To make the PIPES, we sandwiched thin (<1 mm) layers of filamentous attached algae between 2 layers of mesh so that the algae could be isolated and manipulated for repeated PAM measurements. In the 2014 experiment, incubating Cladophora, Rivularia, Microcoleus, and Anabaena at the water surface tended to decrease photosynthetic rates relative to submerged controls, whereas for Nostoc, the photosynthetic rates were higher in floating treatments. In the 2015 experiment, Cladophora and Oedogonium incubated in the warmer, low-flow river margin had persistently lower photosynthesis rates than their counterparts incubated in the thalweg. The PIPES method improves our ability to make PAM measurements on attached algae. PIPES can be used in conjunction with other methods to evaluate taxon-specific responses to environmental conditions and to help us predict how algal assemblages will shift in dominance under different river management regimes.
2017
Vadeboncoeur, Yvonne; Power, Mary
Attached Algae: The Cryptic Base of Inverted Trophic Pyramids in Freshwaters Journal Article
In: Annual Review of Ecology, Evolution, and Systematics, vol. 48, no. 1, pp. 255-279, 2017.
Abstract | Links | BibTeX | Tags: Cladophora, cyanobacteria, diatoms, ERCZO, grazers, lakes, microphytobenthos, periphyton, primary consumer, primary producer, rivers
@article{Vadeboncoeur2017,
title = {Attached Algae: The Cryptic Base of Inverted Trophic Pyramids in Freshwaters},
author = {Yvonne Vadeboncoeur and Mary Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Annu.-Rev.-Ecol.-Evol.-Syst.-2017-Vadeboncoeur.pdf},
doi = {https://doi.org/10.1146/annurev-ecolsys-121415-032340},
year = {2017},
date = {2017-08-11},
urldate = {2017-08-11},
journal = {Annual Review of Ecology, Evolution, and Systematics},
volume = {48},
number = {1},
pages = {255-279},
abstract = {It seems improbable that a thin veneer of attached algae coating submerged surfaces in lakes and rivers could be the foundation of many freshwater food webs, but increasing evidence from chemical tracers supports this view. Attached algae grow on any submerged surface that receives enough light for photosynthesis, but animals often graze attached algae down to thin, barely perceptible biofilms. Algae in general are more nutritious and digestible than terrestrial plants or detritus, and attached algae are particularly harvestable, being concentrated on surfaces. Diatoms, a major component of attached algal assemblages, are especially nutritious and tolerant of heavy grazing. Algivores can track attached algal productivity over a range of spatial scales and consume a high proportion of new attached algal growth in high-light, low-nutrient ecosystems. The subsequent efficient conversion of the algae into consumer production in freshwater food webs can lead to low-producer, high-consumer biomass, patterns that Elton (1927) described as inverted trophic pyramids. Human perturbations of nutrient, sediment, and carbon loading into freshwaters and of thermal and hydrologic regimes can weaken consumer control of algae and promote nuisance attached algal blooms.},
keywords = {Cladophora, cyanobacteria, diatoms, ERCZO, grazers, lakes, microphytobenthos, periphyton, primary consumer, primary producer, rivers},
pubstate = {published},
tppubtype = {article}
}
It seems improbable that a thin veneer of attached algae coating submerged surfaces in lakes and rivers could be the foundation of many freshwater food webs, but increasing evidence from chemical tracers supports this view. Attached algae grow on any submerged surface that receives enough light for photosynthesis, but animals often graze attached algae down to thin, barely perceptible biofilms. Algae in general are more nutritious and digestible than terrestrial plants or detritus, and attached algae are particularly harvestable, being concentrated on surfaces. Diatoms, a major component of attached algal assemblages, are especially nutritious and tolerant of heavy grazing. Algivores can track attached algal productivity over a range of spatial scales and consume a high proportion of new attached algal growth in high-light, low-nutrient ecosystems. The subsequent efficient conversion of the algae into consumer production in freshwater food webs can lead to low-producer, high-consumer biomass, patterns that Elton (1927) described as inverted trophic pyramids. Human perturbations of nutrient, sediment, and carbon loading into freshwaters and of thermal and hydrologic regimes can weaken consumer control of algae and promote nuisance attached algal blooms.
2012
Furey, Paula C.; Lowe, Rex L.; Power, Mary E.; Campbell-Craven, Alexis M.
Cladophora, and epiphytes: shifting interactions through succession Journal Article
In: Freshwater Science, vol. 31, no. 1, pp. 93-107, 2012.
Abstract | Links | BibTeX | Tags: Cladophora, epiphytes, succession
@article{Furey2012,
title = {Cladophora, and epiphytes: shifting interactions through succession},
author = {Paula C. Furey and Rex L. Lowe and Mary E. Power and Alexis M. Campbell-Craven},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Furey_2012_FreshSci.pdf},
doi = {10.1899/11-021.1},
year = {2012},
date = {2012-03-01},
journal = {Freshwater Science},
volume = {31},
number = {1},
pages = {93-107},
abstract = {Midge larvae (Pseudochironomus richardsoni Malloch) in the South Fork Eel River, California, weave retreats in mats of Cladophora glomerata (L.) Kütz. and graze on its algal epiphytes. Densities of these midges and their effects on Cladophora vary over time (seasonally, over the course of succession, and interannually) and space (down the drainage network). New Cladophora growth is green, turns yellow with early colonization by a monolayer of Cocconeis, and rusty-red as it becomes heavily epiphytized by a multistory layer of Epithemia spp. (Rhopalodiaceae), diatoms that contain N-fixing endosymbiotic cyanobacteria. To determine how midges influence epiphyte assemblage structure, we incubated Cladophora in early (green [G]), mid (yellow [Y]), and late (rusty-red [R]) stages of succession with and without midges and assessed changes in epiphyte density and composition. Midge effects on epiphyte composition and density (as measured by % cover on Cladophora filaments) varied with stage of succession and proximity to the ends of midge retreats. Local increases in retreat-associated cyanobacteria occurred in Y and R stages. Percent cover of Cocconeis increased on Y filaments >2 cm from midge retreats (ambient) indicating indirect midge effects (e.g., fertilization). Midges were less effective grazers on adnate Cocconeis cells than on loosely attached Epithemia and often ingested Cladophora in the process of grazing or retreat building, especially in G and Y stages. In contrast, midges that grazed on R Cladophora primarily consumed diatoms in the Rhopalodiaceae. Midge survival and retreat quality were lower in G than in Y or R stages, where retreats were longer and denser. Shifts in epiphyte composition and % cover caused by midge–algae interactions at small scales (µm–m) could affect ecologically significant processes, such as N-fixation and foodweb interactions at larger reach and watershed scales.},
keywords = {Cladophora, epiphytes, succession},
pubstate = {published},
tppubtype = {article}
}
Midge larvae (Pseudochironomus richardsoni Malloch) in the South Fork Eel River, California, weave retreats in mats of Cladophora glomerata (L.) Kütz. and graze on its algal epiphytes. Densities of these midges and their effects on Cladophora vary over time (seasonally, over the course of succession, and interannually) and space (down the drainage network). New Cladophora growth is green, turns yellow with early colonization by a monolayer of Cocconeis, and rusty-red as it becomes heavily epiphytized by a multistory layer of Epithemia spp. (Rhopalodiaceae), diatoms that contain N-fixing endosymbiotic cyanobacteria. To determine how midges influence epiphyte assemblage structure, we incubated Cladophora in early (green [G]), mid (yellow [Y]), and late (rusty-red [R]) stages of succession with and without midges and assessed changes in epiphyte density and composition. Midge effects on epiphyte composition and density (as measured by % cover on Cladophora filaments) varied with stage of succession and proximity to the ends of midge retreats. Local increases in retreat-associated cyanobacteria occurred in Y and R stages. Percent cover of Cocconeis increased on Y filaments >2 cm from midge retreats (ambient) indicating indirect midge effects (e.g., fertilization). Midges were less effective grazers on adnate Cocconeis cells than on loosely attached Epithemia and often ingested Cladophora in the process of grazing or retreat building, especially in G and Y stages. In contrast, midges that grazed on R Cladophora primarily consumed diatoms in the Rhopalodiaceae. Midge survival and retreat quality were lower in G than in Y or R stages, where retreats were longer and denser. Shifts in epiphyte composition and % cover caused by midge–algae interactions at small scales (µm–m) could affect ecologically significant processes, such as N-fixation and foodweb interactions at larger reach and watershed scales.
1992
Power, M. E.; Marks, J. C.; Parker, Michael S.
Variation in the vulnerability of prey to different predators: Community-level consequences Journal Article
In: Ecology, vol. 73, no. 6, pp. 2218-2223, 1992.
Abstract | Links | BibTeX | Tags: anti-predator defenses, attached algae, chironomidae, Cladophora, fish, food webs, omnivory, predatory invertebrates, river communities, strong interactors, trophic cascades
@article{Power1992,
title = {Variation in the vulnerability of prey to different predators: Community-level consequences},
author = {M. E. Power and J. C. Marks and Michael S. Parker},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_1992_Eco3.pdf},
doi = {10.2307/1941469},
year = {1992},
date = {1992-12-00},
journal = {Ecology},
volume = {73},
number = {6},
pages = {2218-2223},
abstract = {Midge larvae (Diptera, Chironomidae) that weave filamentous algae into
retreats or tufts, are dominant primary consumers in a river food web. In a previous
study, densities of tuft-weaving midges increased in the presence of large fish. In the absence of large fish, midges decreased as densities of predatory invertebrates built up, and higher standing crops of algae were maintained. To examine the mechanisms underlying these dynamics, we compared the vulnerability of tuft-weaving midges (naked or in algal tufts) to fish and predatory invertebrates, in field and laboratory experiments. When midges were exposed for 1 h in the river to fish, 15 out of 15 midges in tufts survived, while 15 of 15 naked midges were consumed. Tufts afforded only partial protection to midges exposed to invertebrate predators, however. After 1 h, enhancement of survivorship by tufts was moderately significant for midges exposed to aeshnids, and insignificant for midges exposed to lestids and naucorids. We suggest that the vulnerability of tuft-weaving midges to invertebrate predators, and their relative invulnerability to fish, sets the stage for trophic cascades observed in this system. Fish, by consuming small predators, release midges, which graze down algae. The strong effects of fish as fourth-level consumers would not be predicted from their diets, in which algivorous mayflies dominate (>60% of the insect biomass found in each of the two most common fish species). Nevertheless, fish in this food web act as fourth-level, rather than third-level, consumers because of the differential vulnerability of one guild of primary consumers, which, when released from predation, can suppress plants.},
keywords = {anti-predator defenses, attached algae, chironomidae, Cladophora, fish, food webs, omnivory, predatory invertebrates, river communities, strong interactors, trophic cascades},
pubstate = {published},
tppubtype = {article}
}
Midge larvae (Diptera, Chironomidae) that weave filamentous algae into
retreats or tufts, are dominant primary consumers in a river food web. In a previous
study, densities of tuft-weaving midges increased in the presence of large fish. In the absence of large fish, midges decreased as densities of predatory invertebrates built up, and higher standing crops of algae were maintained. To examine the mechanisms underlying these dynamics, we compared the vulnerability of tuft-weaving midges (naked or in algal tufts) to fish and predatory invertebrates, in field and laboratory experiments. When midges were exposed for 1 h in the river to fish, 15 out of 15 midges in tufts survived, while 15 of 15 naked midges were consumed. Tufts afforded only partial protection to midges exposed to invertebrate predators, however. After 1 h, enhancement of survivorship by tufts was moderately significant for midges exposed to aeshnids, and insignificant for midges exposed to lestids and naucorids. We suggest that the vulnerability of tuft-weaving midges to invertebrate predators, and their relative invulnerability to fish, sets the stage for trophic cascades observed in this system. Fish, by consuming small predators, release midges, which graze down algae. The strong effects of fish as fourth-level consumers would not be predicted from their diets, in which algivorous mayflies dominate (>60% of the insect biomass found in each of the two most common fish species). Nevertheless, fish in this food web act as fourth-level, rather than third-level, consumers because of the differential vulnerability of one guild of primary consumers, which, when released from predation, can suppress plants.
retreats or tufts, are dominant primary consumers in a river food web. In a previous
study, densities of tuft-weaving midges increased in the presence of large fish. In the absence of large fish, midges decreased as densities of predatory invertebrates built up, and higher standing crops of algae were maintained. To examine the mechanisms underlying these dynamics, we compared the vulnerability of tuft-weaving midges (naked or in algal tufts) to fish and predatory invertebrates, in field and laboratory experiments. When midges were exposed for 1 h in the river to fish, 15 out of 15 midges in tufts survived, while 15 of 15 naked midges were consumed. Tufts afforded only partial protection to midges exposed to invertebrate predators, however. After 1 h, enhancement of survivorship by tufts was moderately significant for midges exposed to aeshnids, and insignificant for midges exposed to lestids and naucorids. We suggest that the vulnerability of tuft-weaving midges to invertebrate predators, and their relative invulnerability to fish, sets the stage for trophic cascades observed in this system. Fish, by consuming small predators, release midges, which graze down algae. The strong effects of fish as fourth-level consumers would not be predicted from their diets, in which algivorous mayflies dominate (>60% of the insect biomass found in each of the two most common fish species). Nevertheless, fish in this food web act as fourth-level, rather than third-level, consumers because of the differential vulnerability of one guild of primary consumers, which, when released from predation, can suppress plants.
Power, M. E.
Hydrologic and trophic controls of seasonal algal blooms in northern California rivers Journal Article
In: Archivs fur Hydrobiologie, vol. 125, pp. 385-410, 1992, ISSN: 0003-9136/92/0125-038.
Abstract | Links | BibTeX | Tags: algal blooms, Cladophora
@article{Power1992d,
title = {Hydrologic and trophic controls of seasonal algal blooms in northern California rivers},
author = {M. E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_1992_ArchHydro.pdf},
issn = {0003-9136/92/0125-038},
year = {1992},
date = {1992-00-00},
journal = {Archivs fur Hydrobiologie},
volume = {125},
pages = {385-410},
abstract = {Cladophora glomerata L., a dominant macroalga in lakes and rivers worldwide,
undergoes a marked bloom-detachment-senescence cycle in unregulated rivers of northern California with natural winter flood, summer drought flow regimes. In two regulated channels which probably did not experience scouring floods, however, low standing crops of attached Cladophora turf persisted throughout the year. The contrast between Cladophora phenology in regulated and unregulated rivers suggests that Cladophora cycles may be extrinsically driven by factors related to the hydrograph. Preliminary data on seasonal patterns of animal abundance in regulated and unregulated channels suggest that winter flooding promotes Cladophora blooms in rivers by reducing consumer densities. A working hypothesis relating hydrologic regime, food chain length, and algal phenology in rivers is advanced. This hypothesis predicts that pronounced algal bloom-detachment-senescence cycles will occur in unregulated rivers in Mediterranean climates following winter flooding, and that blooms will not occur in the absence of flooding in regulated channels, or in natural rivers during prolonged drought.},
keywords = {algal blooms, Cladophora},
pubstate = {published},
tppubtype = {article}
}
Cladophora glomerata L., a dominant macroalga in lakes and rivers worldwide,
undergoes a marked bloom-detachment-senescence cycle in unregulated rivers of northern California with natural winter flood, summer drought flow regimes. In two regulated channels which probably did not experience scouring floods, however, low standing crops of attached Cladophora turf persisted throughout the year. The contrast between Cladophora phenology in regulated and unregulated rivers suggests that Cladophora cycles may be extrinsically driven by factors related to the hydrograph. Preliminary data on seasonal patterns of animal abundance in regulated and unregulated channels suggest that winter flooding promotes Cladophora blooms in rivers by reducing consumer densities. A working hypothesis relating hydrologic regime, food chain length, and algal phenology in rivers is advanced. This hypothesis predicts that pronounced algal bloom-detachment-senescence cycles will occur in unregulated rivers in Mediterranean climates following winter flooding, and that blooms will not occur in the absence of flooding in regulated channels, or in natural rivers during prolonged drought.
undergoes a marked bloom-detachment-senescence cycle in unregulated rivers of northern California with natural winter flood, summer drought flow regimes. In two regulated channels which probably did not experience scouring floods, however, low standing crops of attached Cladophora turf persisted throughout the year. The contrast between Cladophora phenology in regulated and unregulated rivers suggests that Cladophora cycles may be extrinsically driven by factors related to the hydrograph. Preliminary data on seasonal patterns of animal abundance in regulated and unregulated channels suggest that winter flooding promotes Cladophora blooms in rivers by reducing consumer densities. A working hypothesis relating hydrologic regime, food chain length, and algal phenology in rivers is advanced. This hypothesis predicts that pronounced algal bloom-detachment-senescence cycles will occur in unregulated rivers in Mediterranean climates following winter flooding, and that blooms will not occur in the absence of flooding in regulated channels, or in natural rivers during prolonged drought.