@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/Annu.-Rev.-Ecol.-Evol.-Syst.-2017-Vadeboncoeur.pdf},
doi = {https://doi.org/10.1146/annurev-ecolsys-121415-032340},
year = {2017},
date = {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, grazers, lakes, microphytobenthos, periphyton, primary consumer, primary producer, rivers},
pubstate = {published},
tppubtype = {article}
}

@article{Warnaars2007,
title = {Abiotic controls on periphyton accrual and metabolism in streams: Scaling by dimensionless numbers},
author = {T. Warnaars and M. Hondzo and M.E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/Warnaars_2007_WaterResRes.pdf},
doi = {10.1029/2006WR005002},
year = {2007},
date = {2007-08-23},
journal = {Water Resources Research},
volume = {43},
number = {8},
abstract = {[1] Increasingly available high-resolution topographic data from remote sensing motivates the search for topographic features that predict abiotic controls on the distribution and performance of biota. We investigated the extent to which periphyton distribution and stream ecosystem metabolism in a steep upland river drainage network could be predicted from physical conditions that varied with local topography. During the summers of 2003 and 2004, we measured periphyton standing crops and gross primary production and ecosystem respiration rates along a 5 km reach of the South Fork Eel River and six of its tributaries in northern California (39°44′N, 123°39′W). We also measured wetted stream width (B), cross-sectionally averaged stream velocity (U), and streambed photosynthetically active solar radiation (PAR) at each site to investigate the degree to which periphyton abundance and metabolism were related to these indicators, which in turn are partially predictable from models relating environmental parameters to the topographic settings. Dimensional analysis, a technique widely used in the field of fluid mechanics, was used to investigate how biotic and abiotic variables may be interconnected in stream environments. Nondimensional groups of variables were formulated on the basis of our field estimates of chosen biotic and abiotic variables. Periphyton biomass was controlled by B9/5, exposure to light PAR1/5, nutrient concentration N5/6, and inverse stream depth H−5/6 and U−1/2. The autotrophic-heterotrophic balance, quantified by the gross primary production to ecosystem respiration rate, scaled with the stream aspect ratio (B/H)equation image and Peclet number Pe = (UB/u*H)equation image, where u* is the shear stress velocity. The scaling relationships were validated against reported field measurements from other geographical areas. The results show nonlinear dependencies among periphyton biomass, stream metabolism, and abiotic variables. These nonlinear relationships point to a need for detailed quantification of biotic and abiotic variables over a range of scales.},
keywords = {Metabolism, periphyton, scaling},
pubstate = {published},
tppubtype = {article}
}

@article{Kupferberg1997,
title = {Facilitation of periphyton production by tadpole grazing: functional differences between species},
author = {Sarah Kupferberg},
url = {https://angelo.berkeley.edu/wp-content/uploads/Kupberberg_1997_FreshBio.pdf},
doi = {10.1046/j.1365-2427.1997.00170.x},
year = {1997},
date = {1997-00-00},
journal = {Freshwater Biology},
volume = {37},
number = {2},
pages = {427-439},
abstract = {1. This study examined how interactions between resources that vary in edibility, and herbivores that vary in ability to acquire resources, control primary productivity. In a northern California river, grazing on Cladophora glomerata, a relatively inedible filamentous green alga, and its more nutritious epiphytic diatoms, was manipulated by exposing cobbles to tadpoles (Rana boylii or Hyla regilla) or excluding tadpoles.

2. Rana indirectly facilitated Cladophora by removing diatoms, whereas Hyla did not significantly change biomass relative to controls. Algal ash-free dry mass on cobbles in Rana treatments was 65 and 72% greater than on controls in two years of investigation (1991 and 1993). Rana decreased epiphytic diatom biovolume by 56% and detritus by 87%.

3. Because nitrogen excretion rates of Hyla and Rana were similar, the differences in effect between the two species were probably due to their roles as consumers rather than as recyclers.

4. The net effect of Rana on periphyton was a 10% increase in areal specific primary productivity (mg O2 h–1 m–2);Hyla caused an 18% decrease. Rana decreased biomass-specific productivity (mg O2 h–1 g–1) 44%;Hyla had no effect.

5. In tadpole exclosures, grazers such as baetid mayfly larvae (mostly Centroptilum sp.) were 4.7 (1991) and 1.8 (1993) times more abundant, and midge larvae (Chironomidae) were 2.5 (1991) and 2 (1993) times more abundant than in Rana enclosures. Invertebrate assemblages in Hyla enclosures, however, were similar to exclosures. Few predatory insects and fish colonized Rana enclosures. Path analyses indicated that Rana affected macroinvertebrates via both interference and exploitation of epiphytic diatoms.},
keywords = {periphyton, tadpole grazing},
pubstate = {published},
tppubtype = {article}
}

@article{Gresens1995,
title = {Grazer diversity, competition and the response of the periphyton community},
author = {Susan E. Gresens},
url = {https://angelo.berkeley.edu/wp-content/uploads/Gresens_1995_Oikos.pdf},
issn = { 0030-1299},
year = {1995},
date = {1995-09-00},
journal = {Oikos},
volume = {73},
number = {3},
pages = {336-346},
abstract = {Enclosure of known densities of three species of benthic grazers demonstrated 1) that grazer species had qualitatively different effects on periphyton, and 2) that competitive interactions decreased growth and development of grazers at natural densities. Grazers (chironomid midge larvae, snails, chydorid Cladocera) did not significantly decrease biomass of periphyton attached to artificial substrates. Midge larvae and snails strongly increased the amount of deposited organic matter (feces) in enclosures. Interaction between midges and snails significantly decreased the amount of deposit present at high grazer densities. Snails increased biomass-specific chlorophyll content of attached algae. Grazers did not significantly alter the taxonomic composition of intact algae on substrates. However, midge density increased up to 70% the proportion of total algal biovolume on substrates which occured in fecal pellets. Total organic matter in enclosures was significantly increased at high midge density. Although periphyton food resources were not depleted, negative density dependent effects existed among grazers. High snail density decreased development of midge larvae by 50%, and reproduction of chydorids by 84%. Snails and midges also suffered from intraspecific competition. In the laboratory, activity of midge larvae decreased 29% in the presence of snails. Interference appears to be the predominant form of competition among these littoral grazers. Competitive interactions among benthic grazers may provide a negative feedback to perturbations at the top or bottom of littoral foodwebs},
keywords = {grazers, periphyton},
pubstate = {published},
tppubtype = {article}
}

@article{Feminella1989,
title = {Periphyton responses to grazing invertebrates and riparian canopy in three Northern California coastal streams},
author = {J.W. Feminella and M.E. Power and V.H. Resh},
url = {https://angelo.berkeley.edu/wp-content/uploads/Feminella_1989_FreshBio.pdf},
doi = {10.1111/j.1365-2427.1989.tb01117.x},
year = {1989},
date = {1989-12-00},
journal = {Freshwater Biology},
volume = {22},
number = {3},
pages = {445-487},
abstract = {1. Field experiments were conducted to examine the impact of grazing invertebrates on periphyton biomass in twenty-one pools across three northern California coastal streams (U.S.A.): Big Sulphur Creek, the Rice Fork of the Eel River, and Big Canyon Creek. Periphyton accrual on artificial substrate tiles was compared in each stream between two treatments: those elevated slightly above the stream bottom to reduce access by grazers (= platforms) and those placed directly on the stream bottom to allow access by grazers (=controls).

2. Crawling invertebrate grazers (cased caddisflies and snails) were numerically dominant in each stream (86% of all grazers in Big Sulphur Creek, 61% in the Rice Fork, 84% in Big Canyon Creek). Platforms effectively excluded crawling grazers, but were less effective in excluding swimming mayfly grazers (Baetidae).

3. Periphyton biomass (as AFDM) on tiles was significantly lower on controls compared to platforms for the Rice Fork, an open-canopy stream, and Big Sulphur Creek, a stream with a heterogeneous canopy. In contrast, no grazer impact was found for Big Canyon Creek, a densely shaded stream. Here, extremely low periphyton biomass occurred for both treatments throughout the 60 day study.

4. The influence of riparian canopy on periphyton growth (i.e. accrual on platforms), grazer impact on periphyton, and grazer abundance was examined for Big Sulphur Creek. As canopy increased (15–98% cover), periphyton biomass on platforms decreased. In contrast, canopy had little influence on periphyton accrual on controls; apparently, grazers could maintain low periphyton standing crops across the full range of canopy levels. The abundance of one grazer species, the caddisfly Gumaga nigricula, was highest in open, sunlit stream pools; abundance of two other prominent grazers, Helicopsyche borealis (Trichoptera) and Centroptilum convexum (Ephemeroptera), however, was unrelated to canopy.},
keywords = {grazing invertebrates, periphyton, riparian canopy},
pubstate = {published},
tppubtype = {article}
}

@article{Hill1987,
title = {Experimental analysis of the grazing interaction between a mayfly and stream algae},
author = {W.R. Hill and A.W. Knight},
url = {https://angelo.berkeley.edu/wp-content/uploads/Hill_1987_Eco.pdf},
doi = {10.2307/1939886},
year = {1987},
date = {1987-12-01},
journal = {Ecology},
volume = {68},
number = {6},
pages = {1955-1965},
abstract = {The interaction between the grazing mayfly Ameletus validus and periphyton in a small, northern California stream was examined by manipulating the density of the mayfly in flow—through plexiglass channels. Containing natural cobble substrate and located in situ, the channels established an initial gradient of A. validus at 0, 0.5, 1, and 4 times the average density of the mayfly in Barnwell Creek. After 23 d, A. validus significantly depressed periphyton standing crop: ash—free dry mass (AFDM) at the 0, 0.5, 1, and 4 N grazer densities was 5.067 ± 1.389 (se), 1.829 ± 0.173, 1.741 ± 0.325, and 1.009 ± 0.199 g/m2 (ANOVA: P < .01). The mayfly also influenced two structural attributes of the periphyton, increasing the amount of chlorophyll a per unit biomass and decreasing the relative contribution of the loose, upper layer to total periphyton biomass. Principal component analysis of algal relative abundances contrasted the effect of grazing on two groups of diatoms. A group of species found primarily in the loose layer of periphyton (Nitzschia spp., Surirella spiralis, Cymatopleura elliptica, and Navicula cryptocephala) was disproportionately reduced in abundance, while an adnate group (Gomphonema clevei, Achnanthes minutissima, Synedra ulna, Rhoicosphenia curvata, and an undescribed species of Epithemia) increased its relative abundance with increasing grazing pressure. The decline in relative abundance of the loose layer diatoms did not appear to result from selective consumption by A. validus, but may have been mediated by a reduction of inorganic sediment in the periphyton by A. validus. Inorganic sediment was highly correlated with the relative abundances of the loose layer group of diatoms, a group of species that are adapted for locomotion on sediment substrates. A. validus growth in the experimental channels was strongly density dependent. Growth in length over 23 d for the 0.5, 1, and 4 N treatments was 2.24 ± 0.17, 1.80 ± 0.23, and 1.15 ± 0.25 mm (ANOVA: P < .01). The significantly greater growth of A. validus at subnormal densities in the experimental channels suggested that the A. validus population in Barnwell Creek was food—limited.},
keywords = {algae, Ameletus, assemblage structure, competition, diatoms, grazing, indirect effects, mayfly, periphyton, standing crop, streams},
pubstate = {published},
tppubtype = {article}
}