Effect of phosphorus stress on <i>Microcystis aeruginosa</i> growth and phosphorus uptake - Fig 1

<p><b>Phosphorus concentrations in culture media in each of the phosphorus treatments on day 3 (a) and on day 6 (b)</b>.</p

The relationships between cell quota and phosphorus treatment.

<p>Fig 4a and 4b show the results of piecewise linear regression for cell quota on day 3 and day 6, respectively. (Note the difference in Y-axis.)</p

Microcystis growth rates related to cell quota.

<p>Growth rates for day 0–3 versus cell quota on day 3 are plotted in Fig 3a. Growth rates for day 3–6 are related to cell quota on day 6 in Fig 3b. The linear models in both figures were the best model and fit for these relationships. (Note the difference in Y-axis.)</p

Effect of phosphorus stress on <i>Microcystis aeruginosa</i> growth and phosphorus uptake

<div><p>This study was designed to advance understanding of phosphorus regulation of <i>Microcystis aeruginosa</i> growth, phosphorus uptake and storage in changing phosphorus (P) conditions as would occur in lakes. We hypothesized that <i>Microcystis</i> growth and nutrient uptake would fit classic models by Monod, Droop, and Michaelis-Menten in these changing conditions. <i>Microcystis</i> grown in luxury nutrient concentrations was transferred to treatments with phosphorus concentrations ranging from 0–256 μg P∙L^-1 and luxury nitrogen. Dissolved phosphorus concentration, cell phosphorus quota, P uptake rate and cell densities were measured at day 3 and 6. Results showed little relationship to predicted models. <i>Microcystis</i> growth was asymptotically related to P treatment from day 0–3, fitting Monod model well, but negatively related to P treatment and cell quota from day 3–6. From day 0–3, cell quota was negatively related to P treatments at <2 μg∙L^-1, but increased slightly at higher P. Cell quota decreased greatly in low P treatments from day 3–6, which may have enabled high growths in low P treatments. P uptake was positively and linearly related to P treatment during both periods. Negative uptake rates and increases in measured culture phosphorus concentrations to 5 μg∙L^-1 in the lowest P treatments indicated P leaked from cells into culture medium. This leakage during early stages of the experiment may have been sufficient to stimulate metabolism and use of intracellular P stores in low P treatments for rapid growth. Our study shows P regulation of <i>Microcystis</i> growth can be complex as a result of changing P concentrations, and this complexity may be important for modeling <i>Microcystis</i> for nutrient and ecosystem management.</p></div

Landscape Prediction and Mapping of Game Fish Biomass, an Ecosystem Service of Michigan Rivers

<div><p></p><p>The increased integration of ecosystem service concepts into natural resource management places renewed emphasis on prediction and mapping of fish biomass as a major provisioning service of rivers. The goals of this study were to predict and map patterns of fish biomass as a proxy for the availability of catchable fish for anglers in rivers and to identify the strongest landscape constraints on fish productivity. We examined hypotheses about fish responses to total phosphorus (TP), as TP is a growth-limiting nutrient known to cause increases (subsidy response) and/or decreases (stress response) in fish biomass depending on its concentration and the species being considered. Boosted regression trees were used to define nonlinear functions that predicted the standing crops of Brook Trout <i>Salvelinus fontinalis</i>, Brown Trout <i>Salmo trutta</i>, Smallmouth Bass <i>Micropterus dolomieu</i>, panfishes (seven centrarchid species), and Walleye <i>Sander vitreus</i> by using landscape and modeled local-scale predictors. Fitted models were highly significant and explained 22–56% of the variation in validation data sets. Nonlinear and threshold responses were apparent for numerous predictors, including TP concentration, which had significant effects on all except the Walleye fishery. Brook Trout and Smallmouth Bass exhibited both subsidy and stress responses, panfish biomass exhibited a subsidy response only, and Brown Trout exhibited a stress response. Maps of reach-specific standing crop predictions showed patterns of predicted fish biomass that corresponded to spatial patterns in catchment area, water temperature, land cover, and nutrient availability. Maps illustrated predictions of higher trout biomass in coldwater streams draining glacial till in northern Michigan, higher Smallmouth Bass and panfish biomasses in warmwater systems of southern Michigan, and high Walleye biomass in large main-stem rivers throughout the state. Our results allow fisheries managers to examine the biomass potential of streams, describe geographic patterns of fisheries, explore possible nutrient management targets, and identify habitats that are candidates for species management.</p><p>Received May 20, 2014; accepted November 6, 2014</p></div

List of LAMP primers used in this study.

<p>List of LAMP primers used in this study.</p

Results obtained for different sample types including: <i>Dreissena polymorpha</i> tissues, <i>Dreissena bugensis</i> tissues, <i>D</i>. <i>polymorpha</i> veligers, 1000X concentrated water, and un-concentrated water.

<p>Information for each sample includes the location, the month and year of sample collection, sample processing, primers used, estimated target per reaction, and measured TTP.</p

Comparison of results between the field-concentrated samples with direct amplification and the unconcentrated samples with DNA extraction and amplification.

<p>This 1:1 plot shows amplification results of the field-concentrated samples with direct amplification as compared to the results of 1 L unconcentrated samples following DNA extraction. Points along the y-axis only amplified with the field-concentrated samples and direct amplification while those along the x-axis only amplified with the unconcentrated method. Points in the center correspond to positive detections using both methods.</p

Direct amplification results for sample collection strategies including 1000X concentration (20 L hand-filtered to 20 mL) and un-concentrated water, at high initial population abundances (circles; open for concentrated and closed for un-concentrated) and low initial population abundances (triangles; open for concentrated and closed for un-concentrated).

<p>At high abundance, no change in TTP was observed between 1000X concentration and water-only. At low abundance, positive results were observed only after 1000X concentration.</p

Results from direct amplification of environmental samples.

<p>Mass estimates for <i>D</i>. <i>polymorpha</i> CO1 (blue circles), <i>D</i>. <i>bugensis</i> CO1 (red triangles), and <i>Dreissena</i> sp. 18S rRNA (black squares). Larger shapes correspond to a high concentration tissue detected.</p