Impacts of invasive Amur honeysuckle, Lonicera maackii , leaf litter on multiple trophic levels of detritus‐based experimental wetlands

2021 ◽  
Author(s):  
Alexis L. Robison ◽  
Josey L. Berta ◽  
Cy L. Mott ◽  
Kurt J. Regester
2006 ◽  
Vol 63 (6) ◽  
pp. 1230-1241 ◽  
Author(s):  
Shannon M Claeson ◽  
Judith L Li ◽  
Jana E Compton ◽  
Peter A Bisson

Salmon carcass addition to streams is expected to increase stream productivity at multiple trophic levels. This study examined stream nutrient (nitrogen, phosphorus, and carbon), epilithic biofilm (ash-free dry mass and chlorophyll a), leaf-litter decomposition, and macroinvertebrate (density and biomass) responses to carcass addition in three headwater streams of southwestern Washington State, USA. We used stable isotopes (δ13C and δ15N) to trace incorporation of salmon-derived (SD) nutrients into stream food webs. SD nutrients were assimilated by biofilm, benthic insects (Perlidae and Limnephilidae spp.), and age-1 steelhead (Oncorhynchus mykiss gairdneri). SD nutrients peaked ~2 weeks after carcass addition for insects and fish feeding on carcasses, but indirect uptake of SD nutrients by biofilm and insects was delayed by ~2 months. A strong stable isotope signal did not always correspond with measurable biological change. At reaches 10–50 m downstream from carcasses, ammonium concentration, leaf-litter decomposition, and benthic insect density all increased relative to upstream control sites. The strongest responses and greatest SD-nutrient uptake were observed 10 m from decomposing carcasses, with effects generally decreasing to undetectable levels 250 m downstream. Carcass addition to headwater streams can have a transient effect on primary and secondary trophic levels, but responses may be limited to specific taxa near carcass locations.


2019 ◽  
Vol 50 (1) ◽  
pp. 547-568 ◽  
Author(s):  
Jane C. Marks

As terrestrial leaf litter decomposes in rivers, its constituent elements follow multiple pathways. Carbon leached as dissolved organic matter can be quickly taken up by microbes, then respired before it can be transferred to the macroscopic food web. Alternatively, this detrital carbon can be ingested and assimilated by aquatic invertebrates, so it is retained longer in the stream and transferred to higher trophic levels. Microbial growth on litter can affect invertebrates through three pathways, which are not mutually exclusive. First, microbes can facilitate invertebrate feeding, improving food quality by conditioning leaves and making them more palatable for invertebrates. Second, microbes can be prey for invertebrates. Third, microbes can compete with invertebrates for resources bound within litter and may produce compounds that retard carbon and nitrogen fluxes to invertebrates. As litter is broken down into smaller particles, there are many opportunities for its elements to reenter the stream food web. Here, I describe a conceptual framework for evaluating how traits of leaf litter will affect its fate in food webs and ecosystems that is useful for predicting how global change will alter carbon fluxes into and out of streams.


2019 ◽  
Vol 89 (2) ◽  
pp. 334-346
Author(s):  
Nereida Melguizo‐Ruiz ◽  
Gerardo Jiménez‐Navarro ◽  
Eva De Mas ◽  
Joaquina Pato ◽  
Stefan Scheu ◽  
...  

2013 ◽  
Vol 6 (1) ◽  
pp. 112-117 ◽  
Author(s):  
Steven M. Castellano ◽  
David L. Gorchov

AbstractSeed dispersal is a crucial process in most plant invasions, but is notoriously difficult to study. One technique to identify the maternal source of dispersed seeds and newly established seedlings is labeling with a stable isotope. We tested whether foliar application of 15N-labeled urea would result in sufficient 15N enrichment to discriminate among seeds and seedlings grown from those seeds of the invasive shrub Lonicera maackii (Amur honeysuckle). We subjected mature L. maackii to all combinations of three concentrations of 15N-labeled urea (0.025 g L−1 [0.003 oz gal−1], 0.20 g L−1, and a 0 g L−1 control) and three temporal treatments (one application in August, one application in September, and five applications spaced every three weeks from June through August). Seeds were collected September to November; some of these were analyzed for %15N and others allowed to germinate and grow into seedlings under two treatments (in potting mix in greenhouse and in woodlot soil outdoors). Seedlings were harvested midway through the next growing season. We found that seeds from plants subjected to the three different concentrations had significantly different %15N levels, and there was a significant interaction between concentration and temporal treatment: the highest seed %15N levels were from plants sprayed five times with 15N-labeled urea, and the second highest from plants sprayed once in September. Similar patterns in %15N levels were found in seedlings, except that those from the 0.025 g L−1 spray treatment were only distinguishable from controls for seedlings grown outdoors in woodlot soil. These findings demonstrate that a single foliar application of 15N in early September is sufficient to label both seeds and seedlings of this invasive shrub, enabling one to identify the source of field-collected seeds or seedlings. This provides a tool for studying patterns and processes in seed dispersal of Amur honeysuckle and potentially other invasive plants.


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