https://www.owrb.ok.gov/quality/standards/pdf_standards/scenicrivers/Smith,%20Tilman%20and%20Nekola%201999.pdf

Eutrophication: impacts of excess nutrient inputs on freshwater, marine, and terrestrial ecosystems

Humans now strongly influence almost every major aquatic ecosystem, and their activities have dramatically altered the fluxes of growth-limiting nutrients from the landscape to receiving waters. Unfortunately, these nutrient inputs have had profound negative effects upon the quality of surface waters worldwide. This review examines how eutrophication influences the biomass and species composition of algae in both freshwater and costal marine systems. An overview of recent advances in algae-related eutrophication research is presented. In freshwater systems, a summary is presented for lakes and reservoirs; streams and rivers; and wetlands. A brief summary is also presented for estuarine and coastal marine ecosystems. Eutrophication causes predictable increases in the biomass of algae in lakes and reservoirs; streams and rivers; wetlands; and coastal marine ecosystems. As in lakes, the response of suspended algae in large rivers to changes in nutrient loading may be hysteretic in some cases. The inhibitory effects of high concentrations of inorganic suspended solids on algal growth, which can be very evident in many reservoirs receiving high inputs of suspended soils, also potentially may occur in turbid rivers. Consistent and predictable eutrophication-caused increases in cyanobacterial dominance of phytoplankton have been reported worldwide for natural lakes, and similar trends are reported here both for phytoplankton in turbid reservoirs, and for suspended algae in a large river. A remarkable unity is evident in the global response of algal biomass to nitrogen and phosphorus availability in lakes and reservoirs; wetlands; streams and rivers; and coastal marine waters. The species composition of algal communities inhabiting the water column appears to respond similarly to nutrient loading, whether in lakes, reservoirs, or rivers. As is true of freshwater ecosystems, the recent literature suggests that coastal marine ecosystems will respond positively to nutrient loading control efforts. Our understanding of freshwater eutrophication and its effects on algal-related water quality is strong and is advancing rapidly. However, our understanding of the effects of eutrophication on estuarine and coastal marine ecosystems is much more limited, and this gap represents an important future research need. Although coastal systems can be hydrologically complex, the biomass of marine phytoplankton nonetheless appears to respond sensitively and predictably to changes in the external supplies of nitrogen and phosphorus. These responses suggest that efforts to manage nutrient inputs to the seas will result in significant improvements in coastal zone water quality. Additional new efforts should be made to develop models that quantitatively link ecosystem-level responses to nutrient loading in both freshwater and marine systems.

http://globalpnetwork.net/sites/default/files/Smith_2003_ESPR_eutrophication_review.pdf

Eutrophication of freshwater and coastal marine ecosystems a global problem

Suggested classification of stream trophic state: distributions of temperate stream types by chlorophyll, total nitrogen, and phosphorus

When determining the suitability of a certain area as a habitat for submersed aquatic vegetation (SAV), light and parameters that modify light (epiphytes, total suspended solids, chlorophyll concentration, nutrients) are the first factors to be taken into consideration. As a result, in the past 10 years, light has been the major focus of SAV research. Even so, we are still unable to explain why SAV often occurs in one area but is absent just a few meters away. Recent studies have shown that SAV may not occur in areas where light levels are adequate but other parameters like wave energy and sulfide concentrations are excessive. It is time to look beyond light when determining SAV habitat requirements. This paper summarizes the impact that physical (waves, currents, tides, and turbulence), geological (sediment grain size and organic matter), and geochemical (mainly sulfide) parameters may have on SAV habitat suitality. Light remains an integral part of the discussion but the focus shifts from maximum depths of distribution (determined mainly by light) to the range SAV can colonize between the maximum and minimum depths of distribution (determined mainly by physical forces). This paper establishes minimum depths of occurrence resulting from the effects of tides and waves, preferred ranges in particle size, organic content, and sulfide, as well as lilfide, as well as limits on currents and waves as related to the capacity to stay rooted at one extreme and diffusive boundary layer constrains at the other.

https://www.jstor.org/stable/info/1352808

Beyond Light: Physical, Geological, and Geochemical Parameters as Possible Submersed Aquatic Vegetation Habitat Requirements

Ths report addresses the following two questions: 
1) What are the loads (flux) of nutrients transported from the Mississippi-Atchafalaya River Basin to the Gulf of Mexico, and where do they come from within the basin? 
2) What is the relative importance of specific human activities, such as agriculture, point-source discharges, and atmospheric deposition in contributing to these loads? 
These questions were addressed by first estimating the flux of nutrients from the Mississippi-Atchafalaya River Basin and about 50 interior basins in the Mississippi River system using measured historical streamflow and water quality data. Annual nutrient inputs and outputs to each basin were estimated using data from the National Agricultural Statistics Service, National Atmospheric Deposition Program, and point-source data provided by the USEPA. Next, a nitrogen mass balance was developed using agricultural statistics, estimates of nutrient cycling in agricultural systems, and a geographic information system. Finally, multiple regression models were developed to estimate the relative contributions of the major input sources to the flux of nitrogen and phosphorus to the Gulf 
of Mexico.

Flux and Sources of Nutrients in the Mississippi-Atchafalaya River Basin

SUMMARY. 

1
 Research was performed in laboratory streams to evaluate periphytic biomass accrual, export, and community composition over a range of limiting nutrient (phosphorus) concentrations with variable velocity, and suspended sediment addition, in comparison to constant velocity and no suspended sediment. In fixed-velocity treatments, velocity increase to 60 cm s−1 significantly enhanced biomass accrual, but further increase resulted in substantial biomass reduction. Average biomass loss rates did not change significantly over a velocity range of 10–80 cm s−1. Diatoms were favoured at relatively high velocities and low phosphorus concentrations, whereas the blue-green Phormidium tended to dominate at higher SRP concentrations and the green Mougeotia seemed to prefer lower velocities.

2
 Sudden increases in velocity raised instantaneous loss rates by an order of magnitude or more, but these high rates persisted only briefly. As a result, marked biomass reductions were not apparent a day after the velocity change. Dominance change from filamentous green or blue-green to diatoms immediately after the increase was reversed within 2 days. Loss rate increases due to solids addition were much smaller than those accompanying velocity increase, but simultaneous velocity elevation and solids addition produced instantaneous loss rates approximately double those with velocity increase alone.

3
 The experiments demonstrated that an elevation in velocity, above that to which algae were accustomed, led to increased loss rates and temporarily reduced biomass. However, recolonization and growth after biomass reduction were apparently rapid. Substantial export of periphyton following solids addition required erosion of the protective boundary layer accompanied by a velocity increase. These results arc applicable to understanding the response of lotic periphytic algae to elevated, turbid storm discharges and similar runoff or high-flow events.

4
 Areal uptake rates of P by algae growing in the laboratory streams increased with soluble reactive phosphorus (SRP) concentration, up to approximately 15 μg I−1 in overlying water. They also increased above 35 cm s −1. Overall, uptake rate seemed to vary inversely with biomass. The ralio of areal uptake rate/biomass was significantly less where mean biomass was 411±6 mg chl a m−2 compared to 223±17 mg chl a m−2.

5
 The results suggested that although nutrient uptake is primarily a surface phenomenon, diffusion to interior cells can also determine the responses of attached communities. Both diffusion and uptake rate were stimulated by increasing nutrient concentration and velocity up to certain levels, but became limited by biofilm thickness and scouring.

Responses of periphyton to changes in current velocity, suspended sediment and phosphorus concentration

Relative coverage of filamentous periphytic algae increased with chlorophyll a (chl a) biomass on natural substrata in 22 northwestern United States and Swedish streams. A biomass range of 100–150 mg chl a m−2 may represent a critical level for an aesthetic nuisance; below those levels, filamentous coverage was less than 20%. Other indices of water quality (dissolved oxygen content and measures of benthic macroinvertebrate diversity) were apparently unaffected by periphytic biomass or filamentous coverage in these streams. Neither was biomass related to limiting nutrient content (soluble reactive phosphorus, SRP), as has been observed in previous experiments using bare rocks in streams and slides in artificial channels. Ambient SRP concentration may not be a useful predicter of periphyton accrual on natural substrates, due to uptake and recycling of P throughout the stream and undetermined losses such as sloughing and grazing.

/pdf/nuisance-biomass-levels-of-periphytic-algae-in-streams-4vb8uputhq.pdf

Marguerite R. Seeley

Papers

Responses of periphyton to changes in current velocity, suspended sediment and phosphorus concentration

Nuisance biomass levels of periphytic algae in streams

Experimental approaches to evaluate mechanisms of developmental toxicity

Evaluation of P19 cells for studying mechanisms of developmental toxicity: application to four direct-acting alkylating agents.

Toxicity of four alkylating agents on in vitro rat embryo differentiation and development.