Grazer Control of Algae in an Ozark Mountain Stream: Effects of Short‐Term Exclusion

Power, Mary E.; Stewart, Arthur J.; Matthews, William J.

doi:10.2307/1941166

Cited by 142 publications

(124 citation statements)

References 16 publications

(24 reference statements)

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“…Macroinvertebrates, other than minute oligochaetes, were not encountered in any of the samples collected, and there was no visible evidence of snail or fish grazing on the periphyton (cf. Power et al 1988). In other New Zealand lakes we have observed large numbers of grazing snails and trichopteran larvae on submerged rock surfaces.…”

Section: Loss Processesmentioning

confidence: 82%

Seasonal dynamics of epilithic periphyton in oligotrophic Lake Taupo, New Zealand

Hawes

Smith

1994

New Zealand Journal of Marine and Freshwater Research

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The biomass and species composition of epilithic periphyton in oligotrophic Lake Taupo was measured over a full year. Measurements of photosynthetic carbon uptake were made during summer and early winter. The lake supported a high biomass of epilithic periphyton throughout the year, averaging 100-600 mg m -2 over the 0-35 m water depth and peaking in early summer. Periphyton extended to at least 40 m depth. Depthintegrated carbon fixation rates of 242-362 mg m -2 h -1 were measured. Periphyton constituted more than 90% of the algal biomass and carbon fixation within the littoral zone, but less than 2% of production on a whole-lake basis. Based on taxonomic composition, periphyton could be divided into three zones, surface (0-2 m), mid water (2-20 m) and deep (> 20 m). The diatoms Aulacosira granulata, Rhopalodia novae zealandiae, Epithemia sorex, and Fragilaria spp. dominated the deep assemblage, Tolypothrix tenuis and Mastogloia elliptica the mid water, and Scytonema, Dichothrix, and filamentous chlorophytes the shallow zone. Indicator pigments, analysed by high-performance liquid chromatography, confirmed these groupings. Biomassspecific rates of photosynthesis were low in shallow water (assimilation number 1 at 1 m depth) and at depths of 20 m and below, photosynthesis was light-limited. We hypothesise that the periphyton community was slow-growing and that the high biomass seen at all depths resulted from gradual accrual with low rates of loss.

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Section: Loss Processesmentioning

confidence: 82%

Seasonal dynamics of epilithic periphyton in oligotrophic Lake Taupo, New Zealand

Hawes

Smith

1994

New Zealand Journal of Marine and Freshwater Research

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“…with further identification to genera in the case of diatoms and cyanobacteria. Algae were quantified using a 'point quadrat method' whereby algae that overlapped with intersections of the ocular grid were identified and tallied (Power et al, 1988;Gelwick & Matthews, 1992). At least 100 fields were counted, with 100 Mean densities (± SE) of algivorous fish are from Yang & Dudgeon (2009a) points (i.e.…”

Section: Algal Assemblage Compositionmentioning

confidence: 99%

“…Filamentous Homoeothrix showed the largest seasonal change in abundance, from 22% in the dry season to 15% in the wet season averaged across the 4 study streams. Homoeothrix can withstand high grazing pressure through basal regeneration (Power et al, 1988;Abe et al, 2001) allowing it to persist during the dry season, but the basal cells may be damaged by scouring and abrasion during spates. Gomphonema was less abundant during the wet season, as might be expected from its upright growth form, but small wet-season decreases in adnate Achnanthes and prostrate Cocconeis were also evident.…”

Section: Wet Season Cyanobacteria Filamentousmentioning

confidence: 99%

“…Algal biomass is reduced or limited by the presence of herbivores but other effects are possible also; for example, grazing fishes can also cause a shift from dominance by diatoms to upright filamentous cyanobacteria (Power et al, 1988;Gelwick et al, 1997;Abe et al, 2006). Such changes could be attributed to grazer 'selectivity' or preference, but may simply reflect morphological constraints of the feeding apparatus that more readily allows ingestion of taxa with erect growth forms or other characteristics that make them susceptible to being eaten (Steinman, 1996).…”

Section: Introductionmentioning

confidence: 99%

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Spatial and seasonal variations in benthic algal assemblages in streams in monsoonal Hong Kong

2009

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Samples from stone surfaces were collected in pools within four unpolluted hillstreams (two shaded and two unshaded) in monsoonal Hong Kong (lat. 23°N) to elucidate the extent of spatial (within and among streams) and temporal (seasonal) variations in algal biomass and assemblage composition. Sampling continued for over 12 months, incorporating the dry season when streams were at baseflow, and the wet season when spates were frequent. We anticipated that algal biomass would be lower in shaded streams and during the wet season, with associated seasonal differences in assemblage composition or relative abundance of different growth forms (e.g. erect versus prostrate). Benthic chlorophyll a (a proxy for algal biomass) varied among streams from an annual mean of 11.0-22.3 mg m -2. Dry-season standing stocks were 18% higher than during the wet season when spate-induced disturbance reduced algal standing stocks. Algal biomass varied significantly at the stream scale, but not at the pool scale, and was lower in unshaded streams, where standing stocks may have been limited by high densities of algivorous balitorid loaches (mainly Pseudogastromyzon myersi). An overriding effect of grazers on algal biomass could also have reduced variations resulting from spateinduced disturbance. Significant differences in assemblage composition among streams, which were dominated by diatoms and cyanobacteria (totally 82 taxa) were not systematically related to shading conditions. Seasonal variations in algal assemblages were statistically significant but rather minor, and did not involve major shifts in composition or growth form caused by spate-induced disturbance. The abundance of filamentous cyanobacteria in all the streams may have been due to 'gardening' by balitorid loaches that removed erect or stalked diatoms and favoured cyanobacteria that persist through basal regeneration of filaments. This explanation requires validation through manipulative experiments.

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“…Here grazing minnows ranged freely throughout all of the pools, despite the presence of smallmouth bass, Micropterus dolomieu. Campostoma maintained dense felts of adnate cyanobacteria (Calothrix), which were overgrown with filamentous diatoms (Melosira) when minnows were excluded (Power et al, 1988). The failure of bass to control grazers and protect algae in this habitat may have been related to larger habitat volume, but also could have stemmed from either species differences, or a switch from a three to a four level regime of trophic control.…”

Section: When Is a Pool A Pool?mentioning

confidence: 99%

Environmental controls on food web regimes: A fluvial perspective

Power

2006

Progress in Oceanography

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Because food web regimes control the biomass of primary producers (e.g., plants or algae), intermediate consumers (e.g., invertebrates), and large top predators (tuna, killer whales), they are of societal as well as academic interest. Some controls over food web regimes may be internal, but many are mediated by conditions or fluxes over large spatial scales. To understand locally observed changes in food webs, we must learn more about how environmental gradients and boundaries affect the fluxes of energy, materials, or organisms through landscapes or seascapes that influence local species interactions. Marine biologists and oceanographers have overcome formidable challenges of fieldwork on the high seas to make remarkable progress towards this goal. In river drainage networks, we have opportunities to address similar questions at smaller spatial scales, in ecosystems with clear physical structure and organization. Despite these advantages, we still have much to learn about linkages between fluxes from watershed landscapes and local food webs in river networks. Longitudinal (downstream) gradients in productivity, disturbance regimes, and habitat structure exert strong effects on the organisms and energy sources of river food webs, but their effects on species interactions are just beginning to be explored. In fluid ecosystems with less obvious physical structure, like the open ocean, discerning features that control the movement of organisms and affect food web dynamics is even more challenging. In both habitats, new sensing, tracing and mapping technologies have revealed how landscape or seascape features (e.g., watershed divides, ocean fronts or circulation cells) channel, contain or concentrate organisms, energy and materials. Field experiments and direct in situ observations of basic natural history, however, remain as vital as ever in interpreting the responses of biota to these features. We need field data that quantify the many spatial and temporal scales of functional relationships that link environments, fluxes and food web interactions to understand how they will respond to intensifying anthropogenic forcing over the coming decades.

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Grazer Control of Algae in an Ozark Mountain Stream: Effects of Short‐Term Exclusion

Cited by 142 publications

References 16 publications

Seasonal dynamics of epilithic periphyton in oligotrophic Lake Taupo, New Zealand

Seasonal dynamics of epilithic periphyton in oligotrophic Lake Taupo, New Zealand

Spatial and seasonal variations in benthic algal assemblages in streams in monsoonal Hong Kong

Environmental controls on food web regimes: A fluvial perspective

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