Mesotrophic Level Research Articles

Stimulation of Phototrophic Pelagic and Benthic Metabolism Close to Sediments in Acidic Mining Lakes

Young, very acidic mining lakes have ecological potentials that are quite different from those of natural lakes: Whereas their primary production and hence their algal biomass is mostly limited by carbon and phosphate, their species composition is largely controlled by the extreme chemical composition of their water (low pH, high metal and sulfate concentrations). As a consequence, their phytoplankton biomass corresponds to the oligo- to mesotrophic level and the dominant taxa of plankton belong to Chrysophyceae, Chlorophyceae, Dinophyceae, Bacillariophyceae and Euglenophyceae whereas the benthic communities are dominated by euglenoids and diatoms. In some lakes, all these taxa are found permanently or sporadically in considerably high quantities either in their hypolimnion or at the sediment surface, indicating a remarkable ecological potential for primary production of these environments. We therefore hypothesize that input of inorganic carbon and phosphorus by groundwater or the replenishment of these nutrients by microbial processes at the sediment/water interface are the main stimulants of primary production in mining lakes.

Selection of phytoplankton associations in Lake Balaton, Hungary, in response to eutrophication and restoration measures, with special reference to the cyanoprokaryotes

Restoration of shallow lakes degraded by eutrophication has often been protracted as a consequence of the accumulation and subsequent releases of phosphorus in their sediments (internal load). Balaton, the largest shallow lake in Central Europe, underwent rapid eutrophication during the 1960s–1970s, during which a west-east gradient of trophic state developed. Measures to reverse the eutrophication and to restore the lake to its historic quality were initiated in the mid-1980s. The external phosphorus load has been decreased considerably but the responses of the phytoplankton have been slight and sometimes counterintuitive. At the level of total biomass, the erstwhile distinctiveness of the down-lake trophic gradient has weakened. The eukaryotic plankton flora has altered little but floristic changes in the dominant cyanoprokaryota are consistent with environmental changes attributable to the eutrophication and subsequent restoration. The dominant species are shown to have been consistently related to variables including sediment-water interactions, physical disturbances and the specific biotic adaptations of the organisms but the phytoplankton development in given years and in given parts of the lake has fluctuated with the stochasticity of the weather. In some years, hypertrophic conditions have continued to develop, marked by the development of prolific cyanoprokaryote blooms; in other years, phytoplankton biomass scarcely exceeded a mesotrophic level, with a species composition resembling that which obtained prior to the recent eutrophication. The species associations represented are believed to be consistent with the responses of groups of species observed elsewhere, suggesting that the patterns of community assembly in the phytoplankton are potentially predictable.

Abundance and productivity of bacterioplankton in a eutrophication gradient of Shimoda Bay

Abundance, specific growth rate, and productivity of bacterioplankton were investigated over a year in Shimoda Bay, Japan, with reference to the eutrophication parameters such as dissolved organic carbon (DOC) concentration. The results from six stations in the bay indicated the formation of a eutrophic gradient ranging from eutrophic (at a river mouth) to mesotrophic (at the bay mouth) levels. Both DOC concentration and UV absorbance were found to have good correlations to bacterioplankton abundance and productivity within the eutrophication range of Shimoda Bay.

Characterization of Brackish Coastal Waters of Different Trophic Levels by Means of Phytoplankton Biomass and Primary Production

AbstractInvestigations on phytoplankton have been carried out in Baltic coastal waters, which are widely separated from the sea. Corresponding to their distance to the sea they differ in their trophic level. Annual phytoplankton production and a mean biovolume of 100‐200 g C · m−2 and 2‐10 mm−3 · 1−1 respectively were found for the mesotrophic level, of 200‐400 g C · m−2 and 10‐20 mm3 · 1−1 for the eutrophic level, and of 400‐600 g C · m−2 and over 20 mm3 · 1−1 for the polytrophic level.In the course of nearly two decades of investigation a slight increase of phytoplankton biovolume, but no increase of primary production was recorded. Some changes in species composition are to be recognized in Greifswalder Bodden, if old literature is compared with recent data. In the Darss‐Zingst boddens a shift from Cyanobacteria dominance towards Chlorophyceae dominance has appeared for at least 5 years. This was on account of the disappearance of Gomphosphaeria pusilla, which is thought to be an indicator species of the mesotrophic level.

Annual Dry Matter Production and Partitioning Over the First 5 Years of a Bed System of Crispin/M.27 Apple Trees at Four Spacings

In order to reveal the community structure characteristics of phytoplankton and the relationships with environmental factors in Hengshan Reservoir, the phytoplankton species composition, abundance, biomass and 12 environmental factors at 4 sampling sites were analyzed from March 2011 to February 2012. A total of 246 phytoplankton species were identified, which belong to 78 genera and 7 phyla. The dominant species were Melosira varians, M. granulate, Cyclotella meneghiniana, Asterianella formosa, Synedra acus, Achnanthes exigua, Ankistrodesmus falcatus, Oscillatoria lacustris, Cryptomonas erosa, Chroomonas acuta, Phormidium tenue and Microcystis aeruginosa, etc. Seasonal variations of species were obvious. The annual abundance and biomass of the phytoplankton were 0.51 x 10(5)-14.22 x 10(5) ind x L(-1) and 0.07-1.27 mg x L(-1), respectively. The values of the Margelef index, Pielou index and Shannon index of the phytoplankton community were 1.10-3.33, 0.26-0.81 and 0.51-2.38, respectively. The phytoplankton community structure was of Bacillariophyta-Cryptophyta type in spring and winter, of Chlorophyta-Cyanophyta type in summer, and of Bacillariophyta type in autumn. Canonical correlation analysis (CCA) showed that temperature, transparency, chemical oxygen demand and pH had the closest relationships with the phytoplankton community structure in the reservoir. Water quality evaluation showed that Hengshan Reservoir was in a secondary pollution with a meso-trophic level.

Relationship between heavy metal pollution and water productivity in Xiamen estuarine harbor

This paper is based on the results of simulation experiments and annual observations on the effect of Cr, Cu, Hg, and Zn on diatom (Chaetoceros sp.Skeletonema costatum andMelosira sulcata) growth. Laboratory experiments reveal many physico-chemical parameters play an important role in the toxicity and accumulation of metals in organisms. The mesotrophic level in the water environment is related to phytoplankton growth. A higher nutrient level can have a negative impact on diatom production. Several of the above metals coexist in the investigated region and exert mainly a negative effect on growth.

A HISTORICAL PERSPECTIVE AND PRESENT WATER QUALITY CONDITIONS IN BEAR LAKE, UTAH-IDAHO

ABSTRACT In the 1975 National Eutrophication Survey Bear Lake had the best overall water quality of all Utah lakes sampled. However, this oligotrophic state would not be retained because of a mesotrophic level of loading. Because of the unique characteristics of the Bear Lake ecosystem and the present danger of cultural eutrophication, the objectives of this 314 Clean Lakes Study were to: (1) quantify the major nonpoint sources of nitrogen and phosphorus into Bear Lake; (2) quantify the major sources of nitrogen and phosphorus in the Bear River prior to its diversion into Dingle Marsh and Bear Lake; (3) determine the nitrogen, phosphorus, and carbon budgets of Dingle Marsh and define the factors which may regulate the flux of these nutrients into Bear Lake; and (4) if necessary, develop a set of viable cost-effective alternatives for the reduction of the nitrogen and phosphorus loading into Bear Lake. Nutrient loading was determined for each major tributary to Bear Lake and the trophic condition of the la...

Microbial readjustment to new balance after influx change of organic material in marine dysphotic layer

Influences of energy and particulate matter were experimentally reduced by eliminating the upper part of the euphotic zone, using a large sediment-seawater enclosure (SSE)in situ in Saanich Inlet, B.C., Canada. The standing stock of heterotrophic microorganisms, as determined by ATP concentration, in the experimental dysphotic zone was not appreciably affected, although the decreased supply of organic material did reduce their rate of nutrient uptake from the environment. In the mesotrophic level of the natural dysphotic zone, the turnover rate of glutamic acid remained near the initial rate by readjusting into a new balance.