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Periphyton (Cyanobacteria (Heath, M., et al. (2016). (Land-use…

- - - - ie low DIN in growth stage
        had +ve effect
  - - - If sediment provides a source of phosphorus for Phormidium, a relationship between sedimentation rates and the prevalence of Phormidium proliferations might be expected. This trend was observed by Wood and Bridge [24] who showed a correlation between increased quantity of deposited fine sediment and sites with Phormidium proliferations in the Maitai River (Nelson, New Zealand).
        
        dissolved inorganic nitrogen (DIN) at site A is below 0.2 mg L-1(www.lawa.org.nz), which is the generally accepted concentration required for bloom formation Wood SA, Wagenhoff A, Young R. The effect of flow and nutrients on Phormidium abundance and toxin production in rivers in the Manawatu-Whanganui region. Cawthron Report No. 2575. 2014. 42 p.
        
        Metallic oxide-bound phosphorus, which consists of phosphorus bound to iron and aluminium oxides
  - - - Internal processes also may play a role in maintaining growth once mats are established (Wood et al. 2015
- - - - variability in algal biomass in this study was not related to in-stream concentrations of TIN
        However, neither TIN nor SRP were low enough at our study sites to be considered limiting
        Postulated that temperature was more important driver of periphyton biomass
    - - Abundance and composition of periphyton and benthic macroinvertebrates were treated as potential nutrient response variables for 74 streams in montane Colorado. The streams ranged from unenriched to mildly enriched with nutrients (N, P).
        
        The study showed no meaningful relationship between periphyton biomass accumulation and concentrations of total or dissolved forms of nitrogen or phosphorus. Nutrient concentrations were also unrelated to periphyton richness, diversity and community composition.
        
        Our study suggests that the nutrient response is suppressed by other controlling factors on the lower limb of the nutrient response curve (i.e. at low nutrient concentrations); a quantitatively significant response occurs only in excess of a threshold beyond which nutrients become dominant over other controlling factors. This interpretation of the results is consistent with published meta-analyses showing lack of nutrient response for a high proportion of experimentally enriched periphyton communities, and division of responses between N and P for communities that do show growth in response to enrichment.
        
        In fact, Dodds
        et al. (2002) have given evidence of thresholds
        (P > 30 lg L)1, N>40 lg L)1) above which there
        appears to be a breakpoint to higher chlorophyll.
        
        The second simulation
        (Fig. 9) shows that temperature and length of growing
        season explain a large difference across elevations in
        the expected (simulated) terminal biomass at the end
        of the growing season: 10 times initial biomass at the
        highest elevations versus 1000 times initial biomass at
        the lowest elevations.
    - - Periphyton biomass rarely responded positively to in-situ experimental enrichment with nitrogen or phosphorus. In the summer, nutrient enrichment overall had no effect on periphyton biomass, while outside the growing season N enrichment had inhibitory effects on periphyton.
        4. Despite these experimental results, surveys of ambient chlorophyll a concentrations in streams across the HBEF demonstrated no relationship between streamwater dissolved inorganic N or P concentrations and benthic chlorophyll a.
        5. Our results suggest that HBEF periphyton communities are not closely regulated by nutrient availability, even during periods of high light availability. The inhibitory effects of nutrient enrichment outside the growing season are interesting, but further research is necessary to elucidate the mechanisms driving these responses
    - - We found that if algae showed significant response to nutrient addition, N limitation (either N alone or N with P) was the most frequent response both on GF/F filters and on wood. Despite the low dissolved nutrient concentrations in our study streams, more than a third of the streams did not show any response to N or P addition
    - - Our results indicate that in headwater streams with intact tree canopies, chronic nutrient enrichment at moderate concentrations may have little detectable effect on benthic algal composition or periphyton biomass. Although nutrients stimulated algal growth rates, the long-term effects of nutrient addition on periphyton biomass were small in magnitude compared with other published values and were potentially suppressed by light availability and invertebrate consumption
    - - In a study of modestly impacted streams in the
        foothills and mountains of Colorado, Lewis and
        McCutchan (2010) found no evidence for correlation of
        periphyton biomass correlation with any form of P and a
        weak but significant correlation with dissolved inorganic
        N concentrations. They suggested that greater concentration
        increases could be necessary to increase benthic algal
        biomass; that invertebrate grazing cannot explain their
        observed patterns; and that other factors, such as algal
        biomass at start of growing season, length of growing
        season, and water temperature, explained more of the
        variation of periphyton biomass in these nutrient-poor to
        modestly enriched streams.
    - - For example, nutrient enrichment can affect
        periphyton and bacterial assemblages directly via com-
        petitive release of nutrient limitation
    - - Only when reference nutrient concentrations are in the upper one third of those expected in the United States, is maximum benthic chlorophyll projected to exceed 100 mg m-2 (a concentration commonly used to indicate nuisance levels) >30% of the time
  - - - At least
        for rivers and streams, suspended algae in the water
        column are distinct from benthic algal biomass, with the
        planktonic biomass forming a minor amount of total
        algal biomass in any but the slowest and largest lentic
        systems. This spatial separation of primary productivity
        could be one reason the chlorophyll/nutrient relationships
        are much weaker in streams than in lakes, but other
        factors could increase variability, including flooding
        (e.g., Biggs 1995), herbivory, and light attenuation by
        riparian vegetation.
      - As we demonstrate,
        there is strong evidence that anthropogenic N and P
        enrichment has influenced eutrophication-related water
        quality in fluvial ecosystems.
      - A literature review indicates (1) stream benthic chlorophyll is significantly correlated to both total N and total P in the water column, with both nutrients explaining more variance than either considered alone; (2) nutrients have increased substantially in many rivers and streams of the United States over reference conditions, and strong shifts in N and P stoichiometry have occurred as well; (3) bioassays often indicate N responses alone or in concert with P responses for autotrophic (primary production and chlorophyll) and heterotrophic (respiration) responses; (4) both heterotrophic and autotrophic processes are influenced by the availability of N and P; and (5) N-fixing cyanobacteria usually do not seem to be able to fully satisfy N limitations in rivers and streams when P is present in excess of N. These data suggest both N and P control should be considered in the eutrophication management of streams.
    - - Meta-analysis of lotic nutrient (N and P) amendment experiments indicated that simultaneous stimulation of benthic algal community biomass by .1 nutrient was the rule,
        not the exception. Addition of a limiting nutrient typically doubled algal biomass, whereas addition of another nutrient generally increased algal biomass ;1.25-fold. N was approximately equally likely as P to be limiting.
    - - Algal biomass is usually related to nutrient concentrations, and this was the case for epilithic algae on cobbles in our streams.
        
        However the relationship is complex when sediment deposition resulting from erosion of soil an stream banks is considered
        
        If streams are aggrading in this manner, their smaller substrates might be less stable and accumulate less algae and moss compared to bedrock and boulders in tussock streams (Biggs, 1996; Suren and Duncan, 1999).
        
        Additionally, fine sediment might become entrained in high flows and scour algal biomass during floods (Schofield and others 2004).
      - Algal biomass is usually related to nutrient concentrations, and this was the case for epilithic algae on cobbles in our streams. However, other factors, including substrate size and stability, hydrology, and invertebrate grazing, affect algal and moss biomass in streams (Biggs, 1996; Biggs and Close, 1989; Suren and Duncan, 1999).
    - - 4.RDAs showed that industrial organic compounds, herbicides and PhC products were the pollutants most strongly associated with measures of biofilm structure and function, whereas dissolved inorganic nitrogen, dissolved organic carbon and hydrological variability were the environmental factors most strongly associated with biofilm responses
  - - - Increasing nutrients by 60–99% of ambient concentrations increased periphyton percentage cover and biomass. Periphyton abundance also increased with increasing duration of exposure to nutrients (2, 4 and 8 weeks); however, short-term pulses of nutrients (2 weeks) had no significant effect in the rural stream. These results indicate that effective management of nutrient delivery, by reducing time periods of high nutrient load, will minimise impacts to benthic environments.
  - - - Periphyton stoichiometry, cotton decay, and cyanobacterial
        cover responded more strongly to annual median DIN
        concentration