phosphorus (P) additions
The levels of phosphorus in Lake Coeur d’Alene have doubled since the 1990's. This worries authorities about the potential growth in algae and increase in heavy metals in the lake.
Read more in The Spokesman-Review: http://www.spokesman.com/stories/2017/nov/15/phosphorus-pollution-flowing-into-lake-coeur-dalen/
stimulated at nutrient concentrations that are now common across human-disturbed landscapes
A city releases water contaminated by agriculture which will have an adverse effect on local ecosystems.
Read more in Lawrence-Journal World: http://www2.ljworld.com/news/2017/nov/15/short-notice-citys-release-nitrogen-contaminated-w/
agricultural streams
Poultry producer is fined by $1.4 million for polluting a local stream.
Read more in WJCT: http://news.wjct.org/post/live-oak-poultry-producer-environmental-groups-reach-deal-over-suwannee-river-pollution
nutrient pollution
William & Mary’s Virginia Institute of Marine Science are studying oysters to see if they could be used to reduce nitrogen levels.
Read more in the Williamsburg Yorktown Daily: https://wydaily.com/2017/11/05/study-suggests-oysters-offer-hot-spot-for-reducing-nutrient-pollution-tek/
Nutrient pollution
Nutient pollution is affecting the production of fisheries in the ocean by creating dead zones in the ocean where there are low levels of oxygen.
Read more in the Iowa Public Radio: http://iowapublicradio.org/post/farmers-sea-say-livelihood-dying-midwest-ag-pollution#stream/0
Algal production increases
An increase on nutrients in nearby river has led to an increase in the levels of algae in these rivers, some of these which are toxic to people.
Read more in nwi.com: http://www.nwitimes.com/business/toxic-algae-once-a-nuisance-now-a-severe-nationwide-threat/article_2b1decfa-43c9-5d80-bf64-173e51a95248.html
inland waters
These are permanent bodies of waters found interior to the coastal waters. These bodies include rivers, lakes and resevoirs.
Long-term nutrient enrichment decouples predator and prey production
This article discusses the effect the addition of nutrients has on an aquatic ecosystem. Originally the author hypothesized an increase of energy transfer from prey to predators because of the increase of nutrients. However, this did not occur because the increase in nutrient led to an increase of predator resistant prey.
Stream nutrient enrichment has a greater effect on coarse than on fine benthic organic matter
This article discusses how an increase in nutrients affects the levels of coarse and fine organic litter. It was observed that there were higher levels of fine organic material which led to an increase in bacteria. However, in the stream with no nutrients added to it, there was an increase in both fungal and bacterial communities.
Nutrient enrichment alters storage and fluxes of detritus in a headwater stream ecosystem
This article demonstrates how the addition of nitrogen and phosphorus led to an increase in the production of fine organic compound by more than 300%. The article also mentions that this increase in fine organic compound will have an effect on the entire ecosystem in that area in the long term.
pretreatment year
Temperature, volumetric flow and discharge were observed and recorded for a year prior to the experiment.
Multiple trophic levels of a forest stream linked to terrestrial litter inputs
This article discusses the importance of terrestrial litter on an aquatic ecosystem. It was observed that organisms that lived in the stream that was being tested were affected the most by the absence of litter and the same effects could be observed throughout the entire ecosystem. However, terrestrial fauna was not affected meaning that it got its carbon from another source.
Lakes and reservoirs as regulators of carbon cycling and climate.
This article mentions the that the rate at which inland water sources release carbon dioxide is equivalent to the rate at which carbon is absorbed by the ocean. Methane is also being release in higher levels from lakes which are beginning to thaw because of increasing temperatures from global warming.
Continental-scale effects of nutrient pollution on stream ecosystem functioning
This experiment was a pan-European research of more than 100 streams in multiple European countries. It helped determine the importance of litter breakdown and states that countries should begin to consider the importance of regulating nutrient levels in aquatic ecosystems.
human-disturbed landscapes
Environments and ecosystems perturbed due to human interference.
Ecosystem metabolism and turnover of organic carbon along a blackwater river continuum
This article discusses the respiration rate of an aquatic ecosystem and uses it to determine patterns of activity found within a river during different seasons. It was observed that there were higher levels of respiration when there were was more organic carbon in the river.
biological processing of C
The biological system includes bacteria, fungi and invertebrates. Fungi colonizes the leaves once they fall in the stream and break down the carbon.
dissolved inorganic nitrogen (DIN)
Dissolved inorganic nitrogen is the combination of nitrogen forms nitrate, nitrite and ammonium. This is the most available form of nitrogen used by algae.
soluble reactive phosphorus (SRP)
SRP is a measure of the filterable portion of phosphate known as orthophosphate.
Nutrient co-limitation of primary producer communities
This article focuses on how nutrients affect the growth of primary producers. The factors that were observed to have the highest effects on the ecosystems were nitrogen and phosphorus levels.
Fig. 1 Terrestrial C residence time was approximately halved with experimental nutrient enrichment.
Photo of the landscape prior to experiment.
Fig. 2 Terrestrial C loss rates from stream reaches increased with N and P concentrations.
Graph illustrating the loss of terrestrial carbon.
Fig. 1 Terrestrial C residence time was approximately halved with experimental nutrient enrichment. Increased nutrient inputs (+) reduced terrestrial particulate C residence time (–) and increased export of fine detrital particles (+) and respiration rates [which increased on C substrates (11) but decreased at reach scales; +/−]. Inset graph: Reach-scale leaf litter loss rates were faster in enriched (dashed lines) than in reference (solid lines) streams; the inverse of these rates is residence time. Colors correspond to the same years in (A) (reference versus enriched streams; N+P experiment; n = 12 annual rates) and to the same streams in (B) (pretreatment versus enriched years; N×P experiment; n = 15 annual rates). Data shown for litter loss are untransformed but were natural log–transformed for analyses and the calculation of loss rates (k, per day). The larger image depicts terrestrial organic C inputs, which enter as leaf litter, wood, and dissolved organic carbon (DOC), and outputs as hydrologic export (fine and coarse particles, DOC) and respired CO2 in deciduous forest streams, using an image of one of the N×P experimental stream sites.
Image illustrating the various sources of carbon observed in the experiment.
terrestrial organic C
This is a carbon source found on land commonly in biotic organisms.
terrestrially derived POC
Terrestrially derived carbon is a source of carbon obtained from land materials such as twigs and leaves.
particulate organic C (POC)
Particulate organic carbon is a source of carbon to the ocean obtained from living organisms and detritus ; it is larger compared to dissolved organic carbon.
Whole-system nutrient enrichment increases secondary production in a detritus-based ecosystem
This article discusses how the addition of nutrients in an aquatic ecosystem affects secondary production. It was noted that there was an increase in secondary consumers most likely caused because of an increase in prey. There was also an increase of secondary consumer predators. It is mentioned that the increase of nutrients in the two years the survey was done resulted in positive effects for the secondary consumers, however, this might eventually change as the carbon levels in the ecosystem begin to decline because of the higher nutrient levels.
Human influences on nitrogen removal in lakes
This article discusses how human practices have led to a increase of nitrogen levels in lakes. The article also mentions that an increase of phosphorus in lakes resulted in the extraction of higher levels of nitrogen. However, the author also states that laws pertaining to the concentration of phosphorus in aquatic habitats should not be removed or relaxed because phosphorus can also have a negative effect on an ecosystem if found in high concentrations.
Editor's Introduction
Within an ecosystem, there are external factors which may threaten the balance. Effects on stream ecosystems are heavily influenced by nutrients. Phosphorus, nitrogen, and carbon balance is essential to keep the ecosystem consistent. When carbon is released from the streams, it does not easily re-enter and goes into different forms. An excess of nutrients and the lack of standards for these ecosystems may be detrimental. Why is it important to conduct such research? Why is it important to care for and monitor other ecosystems?
Experimental nutrient additions accelerate terrestrial carbon loss from stream ecosystems
Effects of Nutrients on Stream Ecosystems
not been previously assessed in response to human-influenced stressors
Although this experiment focuses on microbial and fungal effects on streams, humans sometimes also have an impact.
These effects may include the leaking of septic tanks into bodies of water that increase human waste and phosphorus levels. Fishing and polluting also affect stream ecosystems.
Read more in the attached link.
flow-proportional nitrogen (N) and phosphorus (P)
An irrigation line was used along the 70-150 meter streams to pump in liquid nutrients. The nutrients were pumped proportional to the flow of the water.
Our results generally support the use of litterbags to measure larger-scale C dynamics
It is often necessary to use a simpler model version of a larger system because it is easier to observe.
It is difficult to observe the effects on a whole stream, but the litter bags are observed and represent the carbon loss in streams.
Higher C loss rates at the litterbag scale than the reach scale are expected, because litterbags track distinct parcels of C, whereas reaches receive additional C inputs over time.
Litter in the litter bags have a higher concentration of carbon than the stream, which has carbon more spread out. The litter will have higher loss of carbon but generally represents reach-scales.
pools of benthic fine and coarse POC declined
Benthic fine and coarse particulate organic carbon can be used as a measurement when observing loss of carbon caused by detrivores.
consideration of differences among litter species and potential divergence in rates due to the degree of biological processing (2, 14).
In this experiment, leaf litter from different types of trees were used. The results are in Figure 3.
The structure and chemistry of leaves are different and this determines how fast they may decompose.
For example, tulip poplar decomposes the quickest and has a low carbon to nitrogen ratio. Comparatively, oak decomposes slowly and has a higher carbon to nitrogen ratio.
Management of nutrient effects on both of these pathways would positively affect riverine health.
The purpose of these experiments were to test the effects of nutrients on terrestrial carbon loss that ultimately leads to a change in ecosystems.
Learning the effects and ideal ratios of nitrogen to phosphorus for ecosystems will lead to better policies to protect them.
Litter quantity in the streambed was predicted to be 2.8 times and 7.7 times higher in reference versus nutrient-enriched streams after 6 and 12 months,
In the experiment, it was found that the addition of nutrients encouraged terrestrial organic carbon loss.
This was tested by observing the litterbags of the experimental streams and comparing the data to the litterbags of the control stream.
Since a large amount of mass was lost in the stream with nutrient additions, this gives some evidence that too many nutrients off-balances organic carbon levels.
Reach-scale outputs of C increased as fine POC export, as well as respiration (15).
Fine POC export represents the movement of broken down carbon along the stream. Finer particles move faster and further down a stream as biological factors such as microbes and fungi decomposing the terrestrial organic carbon.
They may limit terrestrial C loss as CO2 and maintain downstream C export, but contribute to depletion of local C resources (22, 23).
Detrivores have a different method of carbon depletion from streams. finer particulate organic carbon travels faster and further away from an area, deleting the area of carbon sources.
Invertebrates may leave the system if there are no food sources and alter the food chain.
biological, rather than physical, processes drove reach-scale rates (table S5).
Biological factors that drive the decomposition of carbon include the consumption and respiration from microbes, vertebrates, and in-vertebrates.
Physical factors include temperature, flow of water, and sediment.
The alignment of the reach- to litterbag- scale rates show that the bags represent the actual rates, and that the bags were not simply filtered through the bag by increased water flow or tear apart because of temperature.
(i.e., litterbag)
The litterbag technique can be used to measure the density lost due to composition by microbes and fungi.
A known type and amount of litter is stuffed in the bag and is left for a certain amount of time in the stream. The bag is then later taken out and weight wet. The bag is allowed to dry and then the dry weight is taken.
The link included shows the method for finding the difference in mass. Additionally, the methods of this paper include grinding the litter and finding the composition.
However, roughly similar-sized effects of N and P on loss rates are strong evidence of co-limitation (Fig. 2 and table S3).
Both nitrogen and phosphorus are contributing factors to changes in terrestrial carbon loss.
Within the ecosystem, different organisms require different ratios of nutrients to react and convert terrestrial carbon to carbon dioxide.
We measured the response of terrestrial C loss rates in whole 70- to 150-m stream reaches (tables S1 and S2).
The experiments were conducted on streams in the Appalachian Mountains of North Carolina.
Because of the elevation, there are little to no fish influencing the data. Mainly microbes and fungi influence the nutrient levels of the streams.
We conducted two manipulative experiments at large spatial and temporal scales and focused our measurements on forest-derived leaf litter, because it is the most biologically active pool of terrestrial C in forest streams and is renewed annually (7). After a pretreatment year, we enriched one stream with N and P at a set ratio for 5 years in a paired watershed design (N+P experiment; a second stream acted as a control) and used expanded N and P gradients in a second experiment in five other streams for 2 years after a pretreatment year (N×P experiment) (table S1).
Two experiments were done separately to test the effects of nitrogen to phosphorus ratios on streams.
Pre-treatment of streams include recording the levels of nutrients and typical conditions throughout a year.
The first experiment had two watersheds with one being the control and the other having an addition of nitrogen and phosphorus to match a ratio that was decided by the scientists.
The second experiment was done on five streams with different combinations of the nitrogen and phosphorus ratio.
dissolved organic carbon (DOC)
This is organic carbon that can be dissolved in water and run through a filter; it is smaller compared to particulate organic carbon.
deciduous forest streams
These forests shed annually and litter the streams, giving them an organic carbon source.
co-limitation
Co-limitation is the limiting of growth caused by two factors, both must be present in a set ratio to have an effect.
There is further visualization in figure 2, where the co-limitation of nitrogen and phosphorus are presented.
sequestration
Sequestration is the collection and storage of carbon dioxide.
In this case, the carbon is being removed from the water and depletes the riverine food webs.