Persistence of a surrogate for a genetically engineered cellulolytic microorganism and effects on aquatic community and ecosystem properties: mesocosm and stream comparisons

1993 ◽  
Vol 39 (7) ◽  
pp. 686-700 ◽  
Author(s):  
Thomas L. Bott ◽  
Louis A. Kaplan
Keyword(s):  
Population Dynamics ◽  
Leaf Litter ◽  
Litter Decomposition ◽  
Bacterial Population ◽  
Genetically Engineered ◽  
Community Respiration ◽  
Cladophora Glomerata ◽  
Bacterial Productivity ◽  
Functional Responses ◽  
Leaf Packs

Our research objectives were to (i) determine the persistence of an introduced surrogate (Cellulomonas sp. NRC 2406) for a genetically engineered microorganism in sediments, growths of Cladophora glomerata (Chlorophyta), and leaf packs, (ii) test community and ecosystem structural and functional responses to the introduced bacteria, and (iii) evaluate the utility of flowing water mesocosms as tools for assessing the fates and effects of introduced bacteria in streams. Cellulomonas sp. densities were determined using fluorescent antibodies; maxima were ≤ 1% of the total bacterial community in each habitat in two experiments, and ≈25% of total densities in leaf packs in a third experiment. Densities declined from postinoculation maxima faster in sediments than in C. glomerata growths and leaf packs. Cellulomonas sp. persisted in leaf packs at densities significantly greater than background. Cellulomonas sp. had no statistically significant effects on primary productivity, community respiration, assimilation ratios, photosynthesis/respiration (P/R) ratios, bacterial productivity, and leaf litter decomposition rates. Cellulase concentrations were positively correlated with Cellulomonas sp. densities ≥ 7 × 108 cells/g dry mass in fresh leaf litter for 2 days following exposure. Total bacterial densities, algal biomass, and total viable biomass sometimes differed between control and experimental systems, but differences were not related to Cellulomonas sp. introduction. Mesocosms were good tools for studying bacterial population dynamics in leaf litter and physiological aspects of litter degradation, but they were less well suited to measuring losses of litter mass and cellulose because physical abrasion during storms accelerated those processes in the field.Key words: bacterial population dynamics, mesocosms, streams, introduced bacteria, Cellulomonas sp., litter decomposition.

scholarly journals Additive Effects of Sediment and Nutrient on Leaf Litter Decomposition and Macroinvertebrates in Hyporheic Zone

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1340
Author(s):  
Md. Khorshed Alam ◽  
Junjiro N. Negishi ◽  
Pongpet Pongsivapai ◽  
Shohei Yamashita ◽  
Tomohiro Nakagawa
Keyword(s):  
Leaf Litter ◽  
Litter Decomposition ◽  
Decomposition Rate ◽  
Hyporheic Zone ◽  
Fine Sediment ◽  
Leaf Litter Decomposition ◽  
Interactive Effects ◽  
Additive Effects ◽  
Functional Responses ◽  
Litter Decomposition Rate

Despite the fact that leaf decomposition constitutes an important function in rivers, how multiple environmental stressors simultaneously affect it remains largely unknown. This study investigated the interactive effects of fine sediments (particle size: <2 mm; experimentally manipulated) and a specific nutrient (i.e., nitrate) on subsurface (hyporheic) leaf litter decomposition rate and macroinvertebrates in a gravel-bed river and its tributary in eastern Hokkaido, Japan. The experiment was conducted by measuring leaf litter decomposition of dried Alnus japonica leaves (3 ± 0.05 g) in benthic and hyporheic zones with and without sediment treatments at four sites that had a gradient of nitrate concentration. The decomposition rate was comparable between the two zones but was slowed down by sediment addition in the hyporheic zone. The functional responses were highly predictable for the individual stressors. Detritivore invertebrates were the main driving component of decomposition in the decreased leaf litter decomposition rate under a higher fine sediment condition, whereas higher nitrate accelerated the leaf litter decomposition rate by stimulated microbe-driven decomposition as well as detritivore feeding. Overall, the negative effect of fine sediment could be offset in the presence of nitrate while considering gross functional responses. We demonstrated the additive effects of fine sediment and nitrate on leaf litter decomposition in the hyporheic zone.

Ants accelerate litter decomposition in a Costa Rican lowland tropical rain forest

2012 ◽  
Vol 28 (5) ◽  
pp. 437-443 ◽  
Author(s):  
Terrence P. McGlynn ◽  
Evan K. Poirson
Keyword(s):  
Mass Loss ◽  
Leaf Litter ◽  
Litter Decomposition ◽  
Rain Forest ◽  
Costa Rican ◽  
Tropical Rain Forests ◽  
Rain Forests ◽  
Food Web Structure ◽  
Litter Bags ◽  
Lowland Rain Forest

Abstract:The decomposition of leaf litter is governed, in part, by litter invertebrates. In tropical rain forests, ants are dominant predators in the leaf litter and may alter litter decomposition through the action of a top-down control of food web structure. The role of ants in litter decomposition was investigated in a Costa Rican lowland rain forest with two experiments. In a mesocosm experiment, we manipulated ant presence in 50 ambient leaf-litter mesocosms. In a litterbag gradient experiment, Cecropia obtusifolia litter was used to measure decomposition rate constants across gradients in nutrients, ant density and richness, with 27 separate litterbag treatments for total arthropod exclusion or partial arthropod exclusion. After 2 mo, mass loss in mesocosms containing ants was 30.9%, significantly greater than the 23.5% mass loss in mesocosms without ants. In the litter bags with all arthropods excluded, decomposition was best accounted by the carbon: phosphorus content of soil (r2 = 0.41). In litter bags permitting smaller arthropods but excluding ants, decomposition was best explained by the local biomass of ants in the vicinity of the litter bags (r2 = 0.50). Once the microarthropod prey of ants are permitted to enter litterbags, the biomass of ants near the litterbags overtakes soil chemistry as the regulator of decomposition. In concert, these results support a working hypothesis that litter-dwelling ants are responsible for accelerating litter decomposition in lowland tropical rain forests.

Litter chemistry prevails over litter consumers in mediating effects of past steel industry activities on leaf litter decomposition

2015 ◽  
Vol 537 ◽  
pp. 213-224 ◽  
Author(s):  
Pierre Lucisine ◽  
Antoine Lecerf ◽  
Michaël Danger ◽  
Vincent Felten ◽  
Delphine Aran ◽  
...  
Keyword(s):  
Leaf Litter ◽  
Litter Decomposition ◽  
Steel Industry ◽  
Leaf Litter Decomposition ◽  
Litter Chemistry ◽  
Mediating Effects

scholarly journals Assessment of Leaf Litter Decomposition in a Pine and Beech Mixed Forest: Case Study in Northern Spain

2020 ◽  
Vol 3 (1) ◽  
pp. 25
Author(s):  
David Candel-Pérez ◽  
J. Bosco Imbert ◽  
Maitane Unzu ◽  
Juan A. Blanco
Keyword(s):  
Chemical Composition ◽  
Forest Management ◽  
Leaf Litter ◽  
Litter Decomposition ◽  
Mixed Forest ◽  
Decomposition Process ◽  
Tree Canopy ◽  
Natural State ◽  
Nutrient Cycles ◽  
Decomposition Rates

The promotion of mixed forests represents an adaptation strategy in forest management to cope with climate change. The mixing of tree species with complementary ecological traits may modify forest functioning regarding productivity, stability, or resilience against disturbances. Litter decomposition is an important process for global carbon and nutrient cycles in terrestrial ecosystems, also affecting the functionality and sustainability of forests. Decomposition of mixed-leaf litters has become an active research area because it mimics the natural state of leaf litters in most forests. Thus, it is important to understand the factors controlling decomposition rates and nutrient cycles in mixed stands. In this study, we conducted a litter decomposition experiment in a Scots pine and European beech mixed forest in the province of Navarre (north of Spain). The effects of forest management (i.e., different thinning intensities), leaf litter types, and tree canopy on mass loss and chemical composition in such decomposing litter were analysed over a period of three years. Higher decomposition rates were observed in leaf litter mixtures, suggesting the existence of positive synergies between both pine and beech litter types. Moreover, a decomposition process was favoured under mixed-tree canopy patches. Regarding thinning treatments significant differences on decomposition rates disappeared at the end of the study period. Time influenced the nutrient concentration after the leaf litter incubation, with significant differences in the chemical composition between the different types of leaf litter. Higher Ca and Mg concentrations were found in beech litter types than in pine ones. An increase in certain nutrients throughout the decomposition process was observed due to immobilization by microorganisms (e.g., Mg in all leaf litter types, K only in beech leaves, P in thinned plots and under mixed canopy). Evaluating the overall response in mixed-leaf litters and the contribution of single species is necessary for understanding the litter decomposition and nutrient processes in mixed-forest ecosystems.

Effect of vertebrate exclusion on leaf litter decomposition in the coastal Atlantic forest of southeast Brazil

2021 ◽  
Author(s):  
Gabriela Garcia Medeiros ◽  
Juliana Antonio ◽  
Michelle Harrison ◽  
Luciana Della Coletta ◽  
Amin Soltangheisi ◽  
...  
Keyword(s):  
Leaf Litter ◽  
Litter Decomposition ◽  
Atlantic Forest ◽  
Leaf Litter Decomposition ◽  
Southeast Brazil
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