Influence of Different Densities of the Mayfly Grazer Heptagenia criddlei on Lotic Diatom Communities

Colletti, Paul J.; Blinn, W.; Pickart, Anne; Wagner, Vincent T.

doi:10.2307/1467314

Cited by 59 publications

(36 citation statements)

References 23 publications

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“…Although individual grazer weights of the two taxa were not correlated, there was a negative association between grazer weight and conspecific biomass. This result suggests intraspecific rather than interspecific competition was an important factor controlling grazer biomass in our channels and may be an important process structuring these herbivore populations in Minor Creek, as has been shown for herbivores in other streams (Colletti et al 1987;Hawkins and Furnish 1987;Lamberti et al 1987b;Feminella and Resh 1990).…”

Section: Discussionsupporting

confidence: 68%

Herbivory and irradiance shape periphytic architecture in a Swiss alpine stream

Wellnitz

Ward

2000

Limnology & Oceanography

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The effects of herbivory and light on epilithic periphyton from Minor Creek (2,200 m above sea level), a Swiss alpine stream, were examined by manipulating light intensity and the densities of two abundant grazers in streamside channels. We hypothesized that the high light intensities in Minor Creek (exceeding 2,000 mol m Ϫ2 s Ϫ1 on the stream bed) would cause photoinhibiton and thus regulate algal composition and biomass accrual. After 18 d, full sunlight had negative effects on all measures of periphytic abundance in streamside channels. A five-level light gradient experiment in Minor Creek corroborated these findings: full sunlight suppressed periphytic accumulation.To test the interactive effects of grazing and light, we used two herbivorous insects with distinctly different feeding structures. Ecdyonurus sp. (Heptageniidae) possesses brushing mouthparts; Drusus lateralis (Limnephilidae) has scraping mandibles. In accordance with a conceptual model that predicts algal physiognomy and herbivore feeding mode regulate algal susceptibility to grazing, we hypothesized that Ecdyonurus would primarily reduce physiognomies composing the periphytic overstory (e.g., stalked and filamentous algae), whereas Drusus would have greater access to understory physiognomies (e.g., prostrate forms). In addition, we hypothesized that tall physiognomies would be less abundant under full sunlight due to the exposure of the periphytic mat to photoinhibiting irradiance. Thus, we expected Ecdyonurus to have a smaller effect on periphyton at high light intensities.Light in channels did not directly modify grazing effects; however, the data suggest light intensity altered periphytic susceptibility to grazing. Channels receiving full sunlight had less periphyton, yet grazer weights did not differ between light treatments despite the fact that weight gain for each grazer was negatively correlated with conspecific biomass, implicating competition for limited periphytic food. Algal responses were most pronounced under grazing by Ecdyonurus, which was associated with decreases in the abundance of six of the seven algal physiognomies. Contrary to model predictions, Ecdyonurus reduced low-lying as well as overstory physiognomies. Drusus, by contrast, was associated with reductions in only four physiognomies. Results from this study suggest that understanding periphytic community responses to grazing will require more sophisticated models of periphytic structure.

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Section: Discussionsupporting

confidence: 68%

Herbivory and irradiance shape periphytic architecture in a Swiss alpine stream

Wellnitz

Ward

2000

Limnology & Oceanography

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“…Diatomu vufgure and Rhoicospheniu curvatu) that dominate in cool tailwater systems (Lowe, 1979). This may have an important long term effect on the composition of primary consumers in tailwater systems because recent studies have demonstrated that larger, upright diatom species are consumed over smaller adnate taxa by macroinvertebrate grazers (Sumner and McIntire, 1982;Steinman et ul., 1987;Colletti et al, 1987). Increases in water temperature may also affect the composition of invertebrate grazers (Ward and Stanford, 1982) and elevated temperature may reduce the standing crop of Cludophoru substratum available for epiphytes (Bellis and McLarty, 1967;Whitton, 1970), both of which emphasize the close interactions within and between trophic levels and physico-chemical parameters.…”

Section: Resultsmentioning

confidence: 99%

Response of epiphytic diatom communities from the tailwaters of glen Canyon Dam, Arizona, to elevated water temperature

Blinn

Truitt

Pickart

1989

Regul. Rivers: Res. Mgmt.

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The composition of epiphytic diatom communities from the cold tailwaters (12°C) of Glen Canyon Dam, Arizona, was analysed after a 2 wk incubation period at 12"C, 18°C and 21°C. There was a significant change in diatom composition between 12°C and 18"C, while no significant changes occurred between 18°C and 21°C. This suggests that a temperature threshold exists between 12°C and 18°C for the diatom flora in the tailwaters of Glen Canyon Dam. At the two higher water temperatures, smaller and closely adnate taxa became more important numerically than larger, upright, cold water stenotherms. The potential importance of this compositional shift in epiphytic diatoms on macroinvertebrate grazers has management implications regarding different release programs from reservoirs.

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“…This could explain the different impact of grazing on B. rutilans in situ and in the laboratory. Growth form may also explain the low grazing impact on the adnate species Cocconeis scutellum, which also positively responded to the presence of grazers in freshwater experiments (Colletti et al 1987, Pan & Lowe 1994. Grazer-resistance of Licmophora abbreviata, however, was more surprising, since the congeneric species L. ehrenbergii was heavily grazed by Idotea chelipes .…”

Section: Effects On Species Compositionmentioning

confidence: 99%

Marine microbenthic community structure regulated by nitrogen loading and grazing pressure

Hillebrand¹,

Worm²,

Lotze³

2000

Mar. Ecol. Prog. Ser.

159

144

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Generalisations on the combined effects of consumers and resources on autotrophs in aquatic food webs largely rely on freshwater studies. In this study, we tested these general concepts with marine benthic microalgae, which are important components of coastal food webs. We manipulated nitrogen availability and herbivore presence in a factorial field experiment in the Western Baltic Sea. Moreover, we investigated how herbivore control varied among 3 sites and 2 seasons and tested for trophic cascades by enhancing demersal fish density at 2 sites. Nitrogen availability and herbivore presence had strong and antagonistic effects on microalgal biomass, species composition and diversity. Herbivores significantly reduced algal biomass, whereas nutrient enrichment led to an increase in biomass. Herbivore effects on microalgal biomass increased with increasing nitrogen availability, indicating a functional response of herbivores to nutrient enrichment. The response of microalgae at the species level suggested a trade-off between nutrient use and grazing resistance which appeared to be linked to algal growth form. Compared to other growth forms, large erect species were most responsive to both nitrogen loading and herbivory. Grazing reduced microalgal diversity at low nutrient supply, but enhanced it at high nutrient supply. Herbivore effects varied considerably among different sites and were stronger in spring than in summer. Manipulations of fish density during summer did not have any effects on microalgal community structure. In conclusion, our results demonstrate that herbivores and nutrients have strong and balancing effects on marine microbenthic community structure.

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Influence of Different Densities of the Mayfly Grazer Heptagenia criddlei on Lotic Diatom Communities

Cited by 59 publications

References 23 publications

Herbivory and irradiance shape periphytic architecture in a Swiss alpine stream

Herbivory and irradiance shape periphytic architecture in a Swiss alpine stream

Response of epiphytic diatom communities from the tailwaters of glen Canyon Dam, Arizona, to elevated water temperature

Marine microbenthic community structure regulated by nitrogen loading and grazing pressure

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