Herbivore-mediated increase in the photosynthetic capacity of marine biofilms: indirect effects of changing microalgal assemblage composition

Kaehler, S.; Froneman, P. W.

doi:10.3354/meps234015

Cited by 23 publications

(31 citation statements)

References 27 publications

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“…However, never-grazed areas did have proportionally more filamentous cyanobacteria, while grazed areas had more coccoid cyanobacteria and lichen. Cell chains and filamentous growth forms are generally absent from grazed biofilms because larger and filamentous taxa are more easily removed by grazers (Nicotri 1977, Norton et al 1990, Kaehler & Froneman 2002. Studies from a wide range of macrophytic systems have likewise found that community responses to grazing are associated with plant growth form (Noy-Meir et al 1989, Huntly 1991.…”

Section: Discussionmentioning

confidence: 99%

“…Effect of grazing history was still evident at termination of the experiment, 7 mo after snail removal, suggesting an enduring effect of grazing. Painter et al (1993) found the effect of prairie dog and Evidence of grazing history is typically ascribed to grazer-instigated shifts in the composition or structural organisation of plant communities (Kaehler & Froneman 2002, McIntire & Hik 2005. The biofilm community could not be sampled in ungrazed halos because of the destructive nature of SEM and HPLC, and therefore we cannot know how the community responded to snail removal.…”

Section: Discussionmentioning

confidence: 99%

“…SEM samples did show, however, that never-grazed areas outside halos had a thick carpet of EPS, detritus and dominant filamentous cyanobacteria, which in grazed areas inside halos was exchanged for abundant colonies of coccoid cyanobacteria and lichen. We suspect that these grazing-induced changes in biofilm community persisted after grazer removal and that they might have impacted on chl a biomass in 2 principal ways: (1) grazing may have boosted biofilm chl a biomass by suppressing the growth of competitively dominant biofilm species with low productivity (Norton et al 1990, Kaehler & Froneman 2002; (2) grazing may have removed a canopy of largely dead biofilm, facilitating light and nutrient penetration for a faster growing community (Hillebrand et al 2000, Kaehler & Froneman 2002.…”

Section: Discussionmentioning

confidence: 99%

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Past and present grazing boosts the photo-autotrophic biomass of biofilms

Skov¹,

Volkelt-Igoe²,

Hawkins³

et al. 2010

Mar. Ecol. Prog. Ser.

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Little is known about the long-term consequences of grazing effects on microphytes. This study tested density-dependent responses to grazer removal on the biomass (chlorophyll a, chl a) and composition of natural high rocky-shore biofilms over a 7 mo period. Gastropod snails Melarhaphe neritoides graze entirely within circular halos generated in biofilms surrounding their refuges. The experiment crossed 3 levels of original snail density per halo with 3 levels of grazing intensity (generated by 100, 50 and 0% snail removal). Areas inside halos from which all snails had been removed sustained significantly higher chl a than never-grazed control areas outside the halos. This effect of grazing history was still present after 7 mo, suggesting that past grazing had an enduring positive influence on biofilm biomass. Against expectation, chl a-biomass was not increased by removing snails, regardless of original grazer density. Half-and fully-grazed halos peaked to a higher chl a than ungrazed halos in spring. Grazing did not affect the presence of major biofilm taxonomic groups, although it did alter their relative contributions. Never-grazed areas were covered by a thick biofilm-detritus complex and had proportionally more filamentous cyanobacteria than grazed areas, which sustained abundant clusters of coccoid cyanobacteria and lichen within micro-pits inaccessible to snail radulae. The present study shows that effects of grazing history are not exclusive to macrophytic systems. Grazers boosted the concentration of micro-autotrophs relative to non-chl a biofilm constituents, probably by removing an unproductive biofilm canopy and facilitating light and nutrient penetration for new growth.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Past and present grazing boosts the photo-autotrophic biomass of biofilms

Skov¹,

Volkelt-Igoe²,

Hawkins³

et al. 2010

Mar. Ecol. Prog. Ser.

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“…The variety of types of EMPB can be greatest in summer (MacLulich 1987). Other studies have investigated how the composition of EMPB is affected by grazing (Nicotri 1977, Hawkins et al 1989, Kaehler & Froneman 2002, grazing history (Skov et al 2010), or succession (MacLulich 1986 To understand the consequences of different temperatures and exposures to waves, we used field spectrometry to estimate distributions, amounts and types of EMPB over 2 yr for different seasons, exposures to waves and heights on the shore, in a warm temperate area (Sydney) and in a subtropical area (Brisbane) . We predicted: (1) greater biomass of the EMPB in Sydney than in Brisbane; (2) more algae during cool than during warm seasons; (3) more EMPB lower than higher on the shore; and (4) that effects of latitude, season, exposure to waves and height on the shore would interact to influence biomass of EMPB.…”

Section: Introductionmentioning

confidence: 99%

Latitudinal and environmental patterns in abundance and composition of epilithic microphytobenthos

Jackson

Underwood²,

Murphy³

et al. 2010

Mar. Ecol. Prog. Ser.

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Epilithic microphytobenthos (EMPB) is of core importance in intertidal assemblages and responds to a variety of environmental variables, including season, light, temperature and exposure to waves. To help understand responses by EMPB to these variables and their interactions, EMPB was compared at 2 different latitudes in eastern Australia. In subtropical Brisbane and temperate Sydney, EMPB was sampled at 4 different heights on shores exposed to, or sheltered from, waves during the austral winters and summers of 2006 to 2008. Trends of increasing biomass with decreasing height on shore supported previous studies. In particular, the interaction between season and height was similar to results of previous studies in Australia. There were no differences in biomass of standing stock between Sydney and Brisbane. Differences in timing of sampling occasions confounded some comparisons, and some observed patterns may be due to differences in rates of recolonisation among treatments. Spectrometric assessment of the composition of pigments in EMPB differed with latitude. Spectral samples were more similar to those from assemblages of cyanobacteria than to assemblages of green algae, and this was more marked in Sydney than in Brisbane. Amounts of chlorophyll a were greater on sheltered shores than on those exposed to waves. These patterns are not easily explained, but serve to illustrate the difficulties of extrapolating patterns and processes from one area to another. Variations in pattern at different heights on the shore and in different years emphasise the need for spatially and temporally extensive data in order to make reliable predictions about EMPB. Improved capacity to make reliable predictions will help us understand how EMPB may respond to our changing climate, which is forecast to be hotter with more frequent storms.

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“…The grazing effect of the larger size classes (macrofauna such as gastropods, insect larvae, herbivorous fish, mayflies) on biomass, diversity, composition, heterogeneity and production of microalgal biofilms has previously been investigated (Liess & Hillebrand 2004, Alvarez & Peckarsky 2005. It is known that macrograzers such as gastropods may stimulate production of attached microalgal communities (Kaehler & Froneman 2002). In contrast, previous studies of the effect of smaller metazoans (meiofauna) are rare.…”

Section: Introductionmentioning

confidence: 99%