Monday, May 23, 2016
10:30 - 12:00

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10:30 - 10:45: / 302-303 BROWN PATHWAYS IN GREEN SYSTEMS: SOURCE, HABITAT AND NUTRIENT EFFECTS ON ORGANIC MATTER BREAKDOWN IN LOWER MISSISSIPPI RIVER BASIN AGRICULTURAL BAYOUS

5/23/2016  |   10:30 - 10:45   |  302-303

BROWN PATHWAYS IN GREEN SYSTEMS: SOURCE, HABITAT AND NUTRIENT EFFECTS ON ORGANIC MATTER BREAKDOWN IN LOWER MISSISSIPPI RIVER BASIN AGRICULTURAL BAYOUS We compared source, habitat and nutrient enrichment effects on breakdown rates of agricultural field (corn residue) and riparian (willow oak) coarse particulate organic matter in natural bayou ecosystems and stream mesocosms. Field data indicated that breakdown rates for corn were significantly higher (k = 0.0321 ± 0.0027 d-1) than willow oak (k = 0.0109 ± 0.0033 d-1) in bayous, and inflow sites had significantly lower breakdown rates than lentic sites for both species. Mesocosm results confirmed that corn residue breakdown rates were significantly higher than willow oak and breakdown rates for both species increased significantly in mesocosms that were enriched with N and P (N+P) compared to control or P enriched mesocosms. Respiration rates for corn residue were double that of willow oak and enrichment effects varied with time, but there was clear experimental evidence that N+P enrichment increased respiration for both species. Our results demonstrate that changes in organic matter sources from riparian species to more labile crop residues, combined with nutrient runoff may impact agricultural water bodies by increasing microbial respiration resulting from faster organic matter breakdown rates.

Jason M. Taylor (Primary Presenter/Author), USDA, Agricultural Research Service, National Sedimentation Lab, jason.taylor@ars.usda.gov;


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10:45 - 11:00: / 302-303 EFFECTS OF THE GRADUAL EXCLUSION OF MACROCONSUMERS AND INVERTEBRATE SHREDDERS ON LEAF DECOMPOSITION

5/23/2016  |   10:45 - 11:00   |  302-303

EFFECTS OF THE GRADUAL EXCLUSION OF MACROCONSUMERS AND INVERTEBRATE SHREDDERS ON LEAF DECOMPOSITION Macroconsumers can influence leaf decomposition in streams because they can feed both on leaf litter and invertebrate shredders. Herein we determined the effects of the gradual exclusion of macroconsumers and shredders on leaf decomposition in an Atlantic Forest stream (Southeast, Brazil). Leaves of a native species (Miconia chartacea) were incubated in 3 different meshes that gradually excluded fishes and crabs (coarse mesh, CM), shrimps (intermediate mesh, IM) and shredders (fine mesh, FM). One control treatment (C), which allowed all organisms to access the leaves, was also used. After 90 days, decomposition rates presented the flowing order: CM > C > FM. The rates observed in IM did not differ from C and FM. The abundance, richness and biomass of invertebrate assemblages did not differ among treatments. However, the proportion of shredders in the biomass of invertebrate assemblages was higher in C and CM. These results reinforce the importance of macroconsumers on leaf processing in tropical streams and suggest that the presence of fishes and crabs might negatively affect the participation of shrimps and large invertebrate shredders on leaf decomposition.

Pâmela Barbosa ( Co-Presenter/Co-Author), University of Vila Velha, pamelabarbosa1@hotmail.com;


Marcelo Moretti (Primary Presenter/Author), University of Vila Velha, msmoretti@gmail.com;


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11:00 - 11:15: / 302-303 IMPACTS OF TERRESTRIAL LEAF LITTER ON THE SEDIMENTS OF SMALL MAN-MADE PONDS IN CENTRAL VIRGINIA

5/23/2016  |   11:00 - 11:15   |  302-303

IMPACTS OF TERRESTRIAL LEAF LITTER ON THE SEDIMENTS OF SMALL MAN-MADE PONDS IN CENTRAL VIRGINIA Terrestrial subsides to aquatic systems can stimulate ecosystem respiration, and support secondary production. Despite substantial research on the importance of leaf litter inputs into streams, most studies in lakes have focused on autochthonous carbon and DOM inputs. Small man-made lakes are abundant in the northern hemisphere and may be the dominant lentic systems in some regions. Understanding how these lakes process terrestrial carbon is critical. We investigated the importance of leaf litter in small man-made lakes in central Virginia. Median leaf litter standing stock was 40 g AFDM m-2 with 12% of the samples exceeding 400 g AFDM m-2. A litter bag experiment showed that tulip poplar litter decomposed slowly with an average breakdown rate of -0.00298 d-1. The slow decay may be explained by limited microbial and detritivore activity. Laboratory incubations showed that leaf litter increased labile DOM and stimulated microbial respiration associated with sediments. Top 1-cm sediments had 2-3x lower fungal biomass than leaf litter (mg g-1 AFDM) while on areal basis (mg cm-2 leaf or sediment) fungal biomass was, surprisingly, 9x higher.

Jonathan Milisci (Primary Presenter/Author), Longwood University, jonathan.milisci@live.longwood.edu;


Jennifer Andrews ( Co-Presenter/Co-Author), Longwood University, jennifer.andrews@live.longwood.edu;


Vlad Gulis ( Co-Presenter/Co-Author), Coastal Carolina University, vgulis@coastal.edu;


Julia Marcellus ( Co-Presenter/Co-Author), Longwood University, julia.marcellus@live.longwood.edu;


Kaitlyn Peters ( Co-Presenter/Co-Author), Longwood University, kaitlyn.peters@live.longwood.edu;


Matthew Waters ( Co-Presenter/Co-Author), Valdosta State University, mwaters@valdosta.edu;


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11:15 - 11:30: / 302-303 BIOFILM COLONIZATION AND SUBSTRATE INFLUENCE PARTICLE RETENTION IN EXPERIMENTAL STREAMS AT ND-LEEF

5/23/2016  |   11:15 - 11:30   |  302-303

BIOFILM COLONIZATION AND SUBSTRATE INFLUENCE PARTICLE RETENTION IN EXPERIMENTAL STREAMS AT ND-LEEF The transport and retention of fine particles in headwater streams plays a significant role in organic matter processing and represents a critical link between upstream and downstream systems. Benthic biofilms potentially alter substrate characteristics and dynamics in porous space; however, the influence of biofilm colonization on particle retention has not been well documented, likely due to inherent heterogeneity of natural systems. We hypothesized that biofilms would increase particle retention in the stream benthos. We used a steady-state particle addition technique to estimate transport distances of a fine particle analogue (corn pollen, 70um) in four 50m experimental streams (Q=2 L/s) with varying substrate size (1cm pea-gravel vs. 10cm small cobble) and complexity (homogenous 50/50 mix vs. alternating sections) on multiple dates over 5 months of biofilm colonization and senescence (June-October) at ND-LEEF. Average particle transport distances were variable across streams, ranging from 6m to unmeasurable, suggesting substrate type is influences retention. Nevertheless, instream retention was highest at the peak of biofilm growth. These results emphasize the dynamic relationship and feedback between the physical and biological environments influencing particle retention in streams.

Arial Shogren (Primary Presenter/Author), Michigan State University, shogrena@msu.edu;


Jennifer L. Tank ( Co-Presenter/Co-Author), University of Notre Dame, tank.1@nd.edu;


Diogo Bolster ( Co-Presenter/Co-Author), University of Notre Dame, diogo.bolster.5@nd.edu;


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11:30 - 11:45: / 302-303 MACROINVERTEBRATE DIVERSITY ASSOCIATED WITH PERIPHYTIC ALGAE ON LEAF DEBRIS

5/23/2016  |   11:30 - 11:45   |  302-303

MACROINVERTEBRATE DIVERSITY ASSOCIATED WITH PERIPHYTIC ALGAE ON LEAF DEBRIS Forested temperate headwater streams are energetically supported by allochthonous inputs, but recent evidence suggests algae may be important components of these streams’ leaf microbial communities. Heterotrophic microbes and macroinvertebrate shredders decompose leaves entering streams. However, while understudied, these leaves may provide substrate for algal colonization and often contain many other macroinvertebrate functional feeding guilds. As such, our research examined macroinvertebrate diversity in leaf packs in relation to algal biomass and leaf tissue stoichiometry. Ten paired coarse and fine mesh leaf bags with Acer rubrum leaves were incubated in December 2015 in each of four forested headwater streams in Maryland (two mountain and two agricultural) for four weeks. Macroinvertebrate diversity (coarse packs), leaf-associated algal chlorophyll-a, and leaf C:N:P were measured for leaf packs. Epilithic chlorophyll-a and natural leaf debris chlorophyll-a were also measured for comparison to incubated leaf packs. Streams showed a gradient of physical characteristics, including conductivity (range: 9.4-459 uS/cm) and pH (range: 5.48-7.85). Results regarding macroinvertebrate diversity, chlorophyll-a, and leaf stoichiometry will be discussed.

Rebecca Eckert (Primary Presenter/Author), University of Maryland, reckert@umd.edu;


William Lamp ( Co-Presenter/Co-Author), University of Maryland, lamp@umd.edu;


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