2013
Power, Mary E.; Holomuzki, Joseph R.; Lowe, Rex L.
Food webs in Mediterranean rivers Journal Article
In: Hydrobiologia, vol. 719, no. 1, pp. 119-136, 2013.
Abstract | Links | BibTeX | Tags: Algal production, Cross-ecosystem fluxes, Detritus Disturbance, Drought, fate Carbon sources, Floods, Food quality, food webs, hydrology, Insect emergence, interaction strength, Mediterranean rivers, River-to-ocean fluxes, seasonality
@article{Power2013,
title = {Food webs in Mediterranean rivers},
author = {Mary E. Power and Joseph R. Holomuzki and Rex L. Lowe},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_2013_Hydrobio.pdf},
doi = {10.1007/s10750-013-1510-0},
year = {2013},
date = {2013-05-28},
journal = {Hydrobiologia},
volume = {719},
number = {1},
pages = {119-136},
abstract = {River food webs are subject to two regimes of longitudinally varying ecological control: productivity and disturbance. Light-limited productivity increases as channels widen downstream. Time windows for growth, however, shrink as discharge increases, substrate particle size decreases, and the frequency of flood-driven bed mobilization increases downstream. Mediterranean rivers are periodically reset by hydrologic events with somewhat predictable timing. Typically, a rainy winter with high river discharge is followed by summer drought with little or no rainfall and slowly declining river flow. The magnitude and timing of winter floods and severity of subsequent summer drought can vary considerably from year to year, however. Episodic scouring floods or prolonged periods of drought are experienced as disturbances, stressors, or opportunities by river biota. The timing, duration, and intensity of these hydrologic controls affect performances of individuals, distribution and abundances of populations, and outcomes and consequences of species interactions. These interactions in turn determine how river food webs will assemble, develop, and reconfigure after disturbance. We discuss how spatial variation in solar radiation and spatial and temporal variations in disturbance affects river food webs under Mediterranean climate seasonality, focusing primarily on long-term observations in the Eel River of northwestern California, USA},
keywords = {Algal production, Cross-ecosystem fluxes, Detritus Disturbance, Drought, fate Carbon sources, Floods, Food quality, food webs, hydrology, Insect emergence, interaction strength, Mediterranean rivers, River-to-ocean fluxes, seasonality},
pubstate = {published},
tppubtype = {article}
}
River food webs are subject to two regimes of longitudinally varying ecological control: productivity and disturbance. Light-limited productivity increases as channels widen downstream. Time windows for growth, however, shrink as discharge increases, substrate particle size decreases, and the frequency of flood-driven bed mobilization increases downstream. Mediterranean rivers are periodically reset by hydrologic events with somewhat predictable timing. Typically, a rainy winter with high river discharge is followed by summer drought with little or no rainfall and slowly declining river flow. The magnitude and timing of winter floods and severity of subsequent summer drought can vary considerably from year to year, however. Episodic scouring floods or prolonged periods of drought are experienced as disturbances, stressors, or opportunities by river biota. The timing, duration, and intensity of these hydrologic controls affect performances of individuals, distribution and abundances of populations, and outcomes and consequences of species interactions. These interactions in turn determine how river food webs will assemble, develop, and reconfigure after disturbance. We discuss how spatial variation in solar radiation and spatial and temporal variations in disturbance affects river food webs under Mediterranean climate seasonality, focusing primarily on long-term observations in the Eel River of northwestern California, USA
2009
Power, M.; Lowe, R.; Furey, P.; Welter, J.; Limm, M.; Finlay, J.; Bode, C.; Chang, S.; Goodrich, M.; Sculley, J.
Algal mats and insect emergence in rivers under Mediterranean climates: Towards photogrammetric surveillance Journal Article
In: Freshwater Biology, vol. 54, no. 10, pp. 2101–2115, 2009.
Abstract | Links | BibTeX | Tags: algae, epiphytic algae, Insect emergence, nitrogen fixers, photogrammetric surveillance
@article{Power2009,
title = {Algal mats and insect emergence in rivers under Mediterranean climates: Towards photogrammetric surveillance},
author = {M. Power and R. Lowe and P. Furey and J. Welter and M. Limm and J. Finlay and C. Bode and S. Chang and M. Goodrich and J. Sculley},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_2009_FreshBio.pdf},
doi = {10.1111/j.1365-2427.2008.02163.x},
year = {2009},
date = {2009-02-23},
journal = {Freshwater Biology},
volume = {54},
number = {10},
pages = {2101–2115},
abstract = {1. In a nitrogen (N)-limited river subject to Mediterranean summer drought hydrology, the colour of macroalgal proliferations changed with successional and seasonal changes in epiphyte assemblages. New growth of the dominant macroalga, Cladophora glomerata, was green, as were proliferations of Oedogonium, Mougeotia and Spirogyra, which did not become heavily colonized with diatoms. Green Cladophora turned yellow as Cladophora filaments became colonized by diatoms that were not N fixers, and turned rust-coloured as later-successional epiphyte assemblages became dominated by dense Epithemia turgida and E. sorex, which both contain N-fixing cyanobacterial endosymbionts.
2. The rate and composition of insect emergence from floating algal mats differed among proliferations of different colour. The rates of emergence (individuals day−1 500 cm−2) of nematoceran flies were three to 25 times greater from yellow or rusty-coloured Cladophora mats than from green Cladophora, Oedogonium or Mougeotia mats that had lower epiphyte densities. Biomass emergence from Cladophora mats that were rusty in colour was eight to 10 times greater than from yellow Cladophora mats, because larger nematocerans dominated in rusty mats (Chironominae versus Ceratopogonidae in yellow mats).
3. Proliferations of Epithemia-infested Cladophora occur at and above drainage areas of about 100 km2 (channel widths of 25–30 m) in this river network, coinciding with the drainage area threshold where a step increase in concentration of total dissolved N is observed during summer.
4. In rivers under Mediterranean climate regimes, algal succession during the prolonged low flow season is less subject to stochastic interruption by spates than in rivers under more continental climates. Under these summer drought conditions, photogrammetric detection of colour changes in algal proliferations may help us track reach or basin-scale change in their ecological functions.},
keywords = {algae, epiphytic algae, Insect emergence, nitrogen fixers, photogrammetric surveillance},
pubstate = {published},
tppubtype = {article}
}
1. In a nitrogen (N)-limited river subject to Mediterranean summer drought hydrology, the colour of macroalgal proliferations changed with successional and seasonal changes in epiphyte assemblages. New growth of the dominant macroalga, Cladophora glomerata, was green, as were proliferations of Oedogonium, Mougeotia and Spirogyra, which did not become heavily colonized with diatoms. Green Cladophora turned yellow as Cladophora filaments became colonized by diatoms that were not N fixers, and turned rust-coloured as later-successional epiphyte assemblages became dominated by dense Epithemia turgida and E. sorex, which both contain N-fixing cyanobacterial endosymbionts.
2. The rate and composition of insect emergence from floating algal mats differed among proliferations of different colour. The rates of emergence (individuals day−1 500 cm−2) of nematoceran flies were three to 25 times greater from yellow or rusty-coloured Cladophora mats than from green Cladophora, Oedogonium or Mougeotia mats that had lower epiphyte densities. Biomass emergence from Cladophora mats that were rusty in colour was eight to 10 times greater than from yellow Cladophora mats, because larger nematocerans dominated in rusty mats (Chironominae versus Ceratopogonidae in yellow mats).
3. Proliferations of Epithemia-infested Cladophora occur at and above drainage areas of about 100 km2 (channel widths of 25–30 m) in this river network, coinciding with the drainage area threshold where a step increase in concentration of total dissolved N is observed during summer.
4. In rivers under Mediterranean climate regimes, algal succession during the prolonged low flow season is less subject to stochastic interruption by spates than in rivers under more continental climates. Under these summer drought conditions, photogrammetric detection of colour changes in algal proliferations may help us track reach or basin-scale change in their ecological functions.
2. The rate and composition of insect emergence from floating algal mats differed among proliferations of different colour. The rates of emergence (individuals day−1 500 cm−2) of nematoceran flies were three to 25 times greater from yellow or rusty-coloured Cladophora mats than from green Cladophora, Oedogonium or Mougeotia mats that had lower epiphyte densities. Biomass emergence from Cladophora mats that were rusty in colour was eight to 10 times greater than from yellow Cladophora mats, because larger nematocerans dominated in rusty mats (Chironominae versus Ceratopogonidae in yellow mats).
3. Proliferations of Epithemia-infested Cladophora occur at and above drainage areas of about 100 km2 (channel widths of 25–30 m) in this river network, coinciding with the drainage area threshold where a step increase in concentration of total dissolved N is observed during summer.
4. In rivers under Mediterranean climate regimes, algal succession during the prolonged low flow season is less subject to stochastic interruption by spates than in rivers under more continental climates. Under these summer drought conditions, photogrammetric detection of colour changes in algal proliferations may help us track reach or basin-scale change in their ecological functions.