Primary consumers and resources: Annual variation in two contrasting reaches of a Patagonian mountain stream

Villanueva, Verónica Díaz; Buria, Leonardo; Albariño, Ricardo

doi:10.1051/limn/2010003

Cited by 15 publications

(17 citation statements)

References 40 publications

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“…Thus, shredder production may decrease in the removal reaches as CPOM availability decreases over time. However, scrapers have responded positively and shredders minimally to riparian forest removal in other studies (Hawkins et al 1982, Benstead et al 2003, Villanueva et al 2010. In our study, the lack of a negative shredder response may have been related to the relatively small reach (∼30 m) we cleared or increased mobilization of CPOM linked to tree removal (e.g., increased potential for CPOM to enter the stream via wind or precipitation because of the close proximity of trees).…”

Section: Functional Responses and Resourcescontrasting

confidence: 46%

Effects of experimental forest removal on macroinvertebrate production and functional structure in tallgrass prairie streams

Vandermyde

Whiles

2015

Freshwater Science

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Encroachment by woody vegetation is a major threat to tallgrass prairie streams, and converts them from open-to closed-canopy systems. This change presumably shifts the relative importance of basal resources from autochthonous to allochthonous and may alter functional feeding group composition and production of consumers. Riparian trees were removed from 2 headwater stream reaches on the Konza Prairie Biological Station to examine effects of forest encroachment and removal. Removal reaches were compared to reaches with naturally open and closed canopies before and after manipulation. Benthic organic matter and macroinvertebrates were sampled monthly for 1 y before (year 1) and after (year 2) riparian forest removal. Total secondary production in removal reaches ranged from 8.9 to 10.2 g ash-free dry mass (AFDM) m −2 y −1 in year 1, and increased significantly to 13.4 to 14.5 g AFDM m −2 y −1 in year 2. Scraper production in removal reaches was 2.8 to 3.9 g AFDM m −2 y −1 in year 1, and increased significantly to 6.0 to 8.7 g AFDM m −2 y −1 in year 2. Shredders did not respond negatively to the removal, but scrapers dominated production (45-60% of total) in open and removal reaches after manipulation. Total production in naturally open reaches was 7.6 to 12.6 g AFDM m −2 y −1 in year 1 and decreased to 6.5 to 9.8 g AFDM m −2 y −1 in year 2. Riparian forest removal altered macroinvertebrate production and functional structure, but higher production in removal reaches than in open reaches after manipulation suggested that natural conditions were not restored 1 y after removal. However, ordinations indicated communities in open and removal reaches became more similar after manipulation. Forest encroachment alters prairie stream structure and function, and riparian forest removal may be an effective restoration and management practice for remaining prairie streams.Prairie habitats once covered ∼162 million ha of North America, but most were significantly altered for agriculture, resulting in <5% of intact prairie remaining (Samson and Knopf 1994). Reduced native ungulate grazing and decreases in fire frequency and intensity in the last century have resulted in the encroachment of native woody species on the few remaining prairie remnants, particularly along riparian corridors. In some regions, fire suppression has resulted in complete conversion to closed-canopy forest in as little as 35 y (Hoch and Briggs 1999). These changes in riparian vegetation ultimately result in a shift from open-to closed-canopy conditions. Riparian vegetation strongly influences the chemical and physical attributes of streams, ultimately affecting ecosystem structure and function (Vannote et al. 1980, Gregory et al. 1991. Historically, because of the frequency of wildfires, ungulate grazing, and hydrological patterns, headwater tallgrass prairie streams were bordered by relatively short riparian prairie vegetation (e.g., grasses, forbs, and shrubs) and characterized as open-canopy systems Dodds 1998, Dodds et al. 2004). These conditions res...

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Section: Functional Responses and Resourcescontrasting

confidence: 46%

Effects of experimental forest removal on macroinvertebrate production and functional structure in tallgrass prairie streams

Vandermyde

Whiles

2015

Freshwater Science

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“…The authors reported an NH 4 uptake rate of 3.51 mg m −2 day −1 . The results of our first experiment, in which ammonium concentration was lowered to the streamwater concentration level in all treatments, would indicate that for a leaf‐mass standing stock of 30 g DM m −2 found in a Patagonian second‐order stream in winter (Díaz Villanueva, Buria & Albariño, 2010), the estimated uptake rate would be 1.00 mg N m −2 day −1 . The positive relationship between ammonium concentration and fungal biomass in our first experiment would indicate that N was a limiting nutrient for the fungal community inhabiting high C : N leaves.…”

Section: Discussionmentioning

confidence: 85%

Positive effect of shredders on microbial biomass and decomposition in stream microcosms

2012

Self Cite

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Summary 1. Animals play a major role in nutrient cycling via excretory processes. Although the positive indirect effects of grazers on periphytic algae are well understood, little is known about top‐down effects on decomposers of shredders living on leaf litter. 2. Nutrient cycling by shredders in oligotrophic forest streams may be important for the microbial‐detritus compartment at very small spatial scales (i.e. within the leaf packs in which shredders feed). We hypothesised that insect excretion may cause local nutrient enrichment, so that microorganism growth on leaves is stimulated. 3. We first tested the effect of increasing concentration of ammonium (+10, +20 and +40 μg NH4+ L−1) on fungal and bacterial biomass on leaf litter in a laboratory experiment. Then we performed two experiments to test the effect of the presence and feeding activity of shredder larvae. We used two species belonging to the trichopteran family Sericostomatidae: the Palaearctic Sericostoma vittatum and the Neotropical Myothrichia murina, to test the effect of these shredders on fungal and bacterial biomass and decomposition on leaves of Quercus robur and Nothofagus pumilio, respectively. All experiments were run in water with low ammonium concentrations (2.4 ± 0.34 to 14.47 ± 0.95 μg NH4+ L−1). 4. After 5 days of incubation, NH4 concentrations were reduced to near‐ambient streamwater concentrations in all treatments with leaves. Fungal biomass was positively affected by increased ammonium concentration. On the other hand, bacteria abundance was similar in all treatments, both in terms of abundance (bacteria cells mg−1 leaf DW) and biomass. However, there was a tendency towards larger mean cell size in treatments with 20 μg NH4 L−1. 5. In the experiment with S. vittatum, fungal biomass in the treatment with insects was more than twice that in the control after 15 days. Bacteria were not detected in treatments with insects, where hyphae were abundant, but they were abundant in treatments without larvae. In the decomposition experiment run with M. murina, leaf‐mass loss was significantly higher in treatments with larvae than in controls. 6. Our hypothesis of a positive effect of shredders on fungal biomass and decomposition was demonstrated. Insect excretion caused ammonium concentration to increase in the microcosms, contributing to microbial N uptake in leaf substrata, which resulted in structural and functional changes in community attributes. The positive effect of detritivores on microbes has been mostly neglected in stream nutrient‐cycling models; our findings suggest that this phenomenon may be of greater importance than expected in stream nutrient budgets.

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“…It is composed by the deciduous tree Ñ ire (Nothofagus antarctica) with a dense shrub cover of native species (Ribes cucullatum, Berberis buxifolia and B. heterophylla, Maytenus chubutensis, and Schinus patagonica) (León et al, 1998). The input of litter fall in Patagonian mountainous environments is a well documented phenomenon (Miserendino & Pizzolón, 2004;Díaz Villanueva et al, 2010); in native deciduous Nothofagus leaf abscission takes place during autumn (mostly concentrated from April to July).…”

Section: Study Sitementioning

confidence: 99%

Life history strategies and production of caddisflies in a perennial headwater stream in Patagonia

Brand

Miserendino

2011

Hydrobiologia

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Synchrony, one of the main traits of population life histories, refers to the degree to which individuals complete a certain stage of the life cycle at the same time. It can be governed by temperature, variations in temperature, photoperiodic cues, detritus inputs, or discharge regimes. We investigated life cycles and secondary production of five caddisfly species in a second order stream in the Patagonian Mountains. In addition, we analyzed what environmental variables were implied in the caddisfly assemblage variation. Mastigoptila sp. (Glossosomatidae) and Eosericostoma aequispina (Helicophidae), Myotrichia murina (Sericostomatidae), Brachysetodes quadrifidus (Leptoceridae), and Neoatopsyche brevispina (Hydrobiosidae) showed univoltine life cycles, with an extended recruitment with no overlapping cohorts and a relatively well-synchronized imaginal emergence taking place during spring summer seasons. However, Myotrichia murina (Sericostomatidae) displayed a complex life cycle with mixed populations taking 10-12 months to develop, and pupae being collected almost continuously. The annual secondary production per species varied from 11.06 (E. aequispina) to 310.5 mg m -2 year -1 (M. murina), being overall caddisfly production (0.5 g m -2 year -1 ) similar to that reported for cold springs in other regions. The highest growth rates (K) were observed during late winter and spring (mostly September) and ranged from 0.70 to 3.70% day -1 in M. longicornuta and N. brevispina, respectively. Redundancy analysis indicated that seasonally dynamic variables, water temperature, discharge, and detritus biomass were the main predictors of caddisfly assemblage variation; consequently at this cold stream (mean annual 5.9°C), with a regular availability of food supply, these parameters ruled Trichoptera life histories and secondary production. As documented for other mountainous temperate areas, synchrony would be a dominant trait on life histories of Trichoptera species inhabiting Patagonian streams.

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Primary consumers and resources: Annual variation in two contrasting reaches of a Patagonian mountain stream

Cited by 15 publications

References 40 publications

Effects of experimental forest removal on macroinvertebrate production and functional structure in tallgrass prairie streams

Effects of experimental forest removal on macroinvertebrate production and functional structure in tallgrass prairie streams

Positive effect of shredders on microbial biomass and decomposition in stream microcosms

Life history strategies and production of caddisflies in a perennial headwater stream in Patagonia

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