Cascading Effects of Decreased Salinity on the Plankton Chemistry, and Physics of the Great Salt Lake (Utah)

1990 ◽  
Vol 47 (1) ◽  
pp. 100-109 ◽  
Author(s):  
Wayne A. Wurtsbaugh ◽  
Therese Smith Berry

Physical, chemical and biological variables were measured in the Great Salt Lake during 1985–87, when salinity in the mixolimnion was near 50 g/L, much lower than the 250 g/L maxima recorded in 1963. Decreased salinity has been accompanied by a change in macrozooplankton from one species (Artemia franciscana), to an assemblage with one rotifer, two copepods, Artemia, and the corixid Trichocorixa verticalis. Predation by the corixid may now limit Artemia to low densities (<100∙m−3). The low biomass of Artemia and other zooplankton has reduced grazing pressure on the algal community so that high chlorophyll levels (5-44 mg∙m−3) and low Secchi depths (0.8–2.7 m) are now present throughout the year. The algae presently reduce soluble reactive phosphorus and inorganic nitrogen in the mixolimnion to below 5 and 50 μg∙L−1, respectively. Shading in the 7-m thick mixolimnion by algae, and by purple-sulfur bacteria in the chemocline, decreases light penetration so that the monimolimnion now maintains a nearly constant temperature (9–11 °C) throughout the year. The data support the hypothesis that the effects of corixid predation have cascaded through the Great Salt Lake, affecting herbivores, nutrients and thermal stratification.

2016 ◽  
Vol 77 (3) ◽  
pp. 495-505 ◽  
Author(s):  
R. S. Cordeiro ◽  
J. E. L. Barbosa ◽  
G. Q. Lima Filho ◽  
L. G. Barbosa

Abstract The hydrological periods drive the structure and organization of aquatic communities in semiarid regions. We hypothesize that a decrease of the precipitation during the dry period will favor the development of the periphytic algal community, leading to higher richness and density in this period. To test this hypothesis, we investigated the changes in the periphytic algal community structure in three shallow and eutrophic ecosystems of the Brazilian semiarid. The sampling was performed between 2007 and 2010 at two-mensal intervals. The sampling of periphytic algal was performed in aquatic macrophytes and rocks. The abiotic variables were analyzed simultaneously. Dominance in diatoms, cyanobacteria and chlorophytes, respectively, was observed in two periods. In the dry period, waters were alkaline and had high concentrations of nitrate and total phosphorus associated with the highest densities of Bacillariophyceae. In the rainy period the water was warmer, oxygenated and high concentrations of ammonia and soluble reactive phosphorus with diatoms remained dominant but with reduced density, while cyanobacteria and chlorophytes increased. Overall, periphytic algal community composition no responded to changes in the hydrological periods. However, the hydrological periods altered the dynamics of periphytic algal community, supported by the alternation of the most representative classes (diatoms and cyanobacteria) between the hydrologic periods. Our data suggest that the morphometric and chemical and physical characteristics of lentic aquatic ecosystems studied were more important in the dynamics of periphytic algal community than the hydrological periods and types of substrates.


2019 ◽  
Vol 78 (2) ◽  
Author(s):  
Carlos Y. B. Oliveira ◽  
Cicero D. L. Oliveira ◽  
Ayanne J. G. Almeida ◽  
Alfredo O. Gálvez ◽  
Danielli M. Dantas

The temporal phytoplankton biomass variation at two Neotropical reservoirs during an extreme drought season were analyzed. Here we sought to evaluate the main abiotic factors involved in dynamics of phytoplankton during this drought period. The main difference between the reservoirs was the intensive fish and shrimp farming in one of the reservoirs. For quantitative analysis, sampling with bottles were carried out at an average depth of 0.5m. Water temperature, pH and electrical conductivity parameters were measured in situ and water samples were collected for dissolved inorganic nitrogen and soluble reactive phosphorus analyses. Aquaculture was probably one among the causes for the reservoirs were so different in the physical and chemical variables, as shown by the principal components analysis. The results showed specific groups dominance in both reservoirs. In the Cachoeira II reservoir, an invasive dinoflagellate, Ceratium furcoides, was present in all analyzed months, while, in the Saco I reservoir, cyanobacteria group represented more than 50% of phytoplankton biomass, mainly Microcystis aeruginosa and Dolichospermum sp. In two reservoirs precipitation, soluble reactive phosphorus and electrical conductivity were positively related with phytoplankton. Phytoplankton biomass was considerably larger in the Cachoeira II reservoir, due to the greater size and biovolume of the dominant dinoflagellate. These findings suggest that species dominance in extreme drought events may be favored.


2000 ◽  
Vol 57 (7) ◽  
pp. 1342-1354 ◽  
Author(s):  
Garry J Scrimgeour ◽  
Patricia A Chambers

Large-scale patterns in epilithic biomass and nutrient status were evaluated at 33 sites located upstream and downstream of point-source anthropogenic effluents in the Athabasca and Wapiti-Smoky rivers in Alberta, Canada. Multiple regression showed that epilithic chlorophyll a was significantly (p < 0.0001) related to concentrations of dissolved inorganic nitrogen and marginally (p = 0.06) significantly related to soluble reactive phosphorus. Epilithic biomass was up to 50 times higher immediately downstream of point-source inputs compared with sites upstream and those 20-150 km downstream. Data from nutrient diffusing substrata showed that the epilithon at 18 of the 33 sites was nutrient limited, while 14 sites showed no nutrient limitation; interpretation of the remaining site was inconclusive. Of the 18 nutrient-limited sites, six were nitrogen limited, five were phosphorus limited, and seven were co-limited. Multiple discriminant function analysis showed that the combined concentration of soluble reactive phosphorus and dissolved inorganic nitrogen was a significant discriminator between deplete and replete sites.


1993 ◽  
Vol 50 (3) ◽  
pp. 665-675 ◽  
Author(s):  
Frank J. Triska ◽  
Catherine M. Pringle ◽  
Gary W. Zellweger ◽  
John H. Duff ◽  
Ronald J. Avanzino

The composition, transformation, and transport of dissolved inorganic nitrogen (DIN) was compared in waters associated with two lowland streams in Costa Rica. The Salto River is enriched by geothermal-based soluble reactive phosphorus (SRP), which raises the concentration up to 200 μg/L whereas Pantano Creek, an unimpacted tributary, has an SRP concentration <10 μg/L. Ammonium concentration in springs adjacent to the Salto and Pantano was typically greater than channel water (13 of 22 locations) whereas nitrate concentration was less (20 of 22 locations). Ground waters were typically high in ammonium relative to nitrate whereas channel waters were high in nitrate relative to ammonium. Sediment slurry studies indicated nitrification potential in two sediment types, firm clay (3.34 μg N∙cm−3∙d−1) and uncompacted organic-rich sediment (1.76 μg N∙cm−3∙d−1). Ammonium and nitrate amendments to each stream separately resulted in nitrate concentrations in excess of that expected after correction for dilution using a conservative tracer. SRP concentration was not affected by DIN amendment to either stream. SRP concentration in the Pantano appeared to be regulated by abiotic sediment exchange reactions whereas DIN composition and concentration were regulated by a combination of biotic and abiotic processes.


2002 ◽  
Vol 6 (3) ◽  
pp. 403-420
Author(s):  
C. Neal

Abstract. The effect of felling on stream nitrate, ammonium and soluble reactive phosphate (SRP) concentrations is examined for acidic and acid sensitive Sitka Spruce afforested catchments with podzolic and gley soils in mid-Wales. For the streams draining the felled podzolic areas, the concentrations of nitrate can be up to an order of magnitude higher than pre-fell values and post-fell concentrations can even be lower than the pre-fell values. Felling for the podzolic soils barely leads to any changes in ammonium or SRP concentration. For the gley soils, felling results in an order of magnitude increase in nitrate, ammonium and SRP for a small drainage ditch, but the pulse is much reduced before it reaches the main Nant Tanllwyth channel. Rather, within-catchment and within-stream processes not only imbibe nitrate, ammonium and SRP fluxes generated, but in the case of nitrate, concentrations with- and post-felling are lower than pre-felling concentrations. The flux changes involved are described in terms of (a) input-output relationships and (b) "felling disruption" and "felling recovery responses". The findings are linked to issues of hydrobiological controls and forestry management. Keywords: Plynlimon, Hafren, Hore, streams, nitrate, ammonium, SRP, phosphorus, soluble reactive phosphorus, phosphate, orthophosphate, Sitka spruce, forestry, felling, podzol, gley


2003 ◽  
Vol 30 (2) ◽  
pp. 317-330 ◽  
Author(s):  
L. J. Dorr ◽  
D. H. Nicolson ◽  
L. K. Overstreet

Howard Stansbury's classic work is bibliographically complex, with two true editions as well as multiple issues of the first edition. The first edition was printed in Philadelphia; its 487 stereotyped pages were issued in 1852 under two different titles with three variant title-pages (an official US government issue and two trade issues). A second edition was printed in Washington in 1853 and had 495 typeset pages (with corrections and additions in the appendices). The issue of 1855 is identical to the 1852 trade issue, except for the change of the date on the title-page. Each issue and edition, with its bindings and plates, is described.


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