The effects of pH and aluminum on the growth of the acidophilic diatom Asterionella ralfsii var. americana

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110027/1/lno19913610123.pd

Protectiveness of Aquatic Life Criteria for Copper Against Olfactory and Behavioral Effects in Freshwater and Saltwater Fish

Stormwater runoff can result in episodic increases of copper concentrations in receiving waters of the Salish Sea basin. Based on several laboratory studies demonstrating that short-term exposures to low copper concentrations can cause olfactory and behavioral effects in Pacific salmon and trout, there is concern that these short-term increases in copper concentrations during storm events could be adversely impacting salmon and trout populations. For example, copper-induced olfactory impairment could potentially reduce the ability of juvenile salmon to avoid predators. Although behavior and olfactory impairment are more sensitive endpoints than the acute lethality endpoint commonly used for evaluating short-term exposures to chemicals, the data available to-date indicate that ambient water quality criteria (AWQC) for copper in freshwater are protective against both behavioral effects and olfactory impairment in fish, particularly when the AWQC were derived using the freshwater biotic ligand model (BLM). The BLM is a bioavailability-based model that predicts copper toxicity as a function of several water chemistry parameters, including, dissolved organic carbon (DOC), pH, alkalinity, calcium, and several other ions in freshwater. Less data on the olfactory and behavioral effects of copper on saltwater species are available relative to that available in fresh water. No experimental evidence available to-date indicates that copper concentrations in marine waters at or below the current EPA marine AWQC for copper (CMC = 4.8 µg/L, CCC = 3.1 µg/L) adversely affects the behavior of any marine fish species tested. The pending draft BLM-based saltwater AWQC for copper also appear to be protective against both behavioral effects and olfactory impairment (key water chemistry parameters in the saltwater BLM are DOC, pH, and salinity). An evaluation of copper concentrations in some representative receiving waters in the Salish Sea basin during storm events, and comparisons to BLM-based copper criteria and behavioral and olfactory effects thresholds for copper, will be presented

The effect of pH, aluminum, and chelator manipulations on the growth of acidic and circumneutral species of Asterionella

The growth rates of two diatoms, acidophilic Asterionella ralfsii and circumneutral A. formosa , were differentially affected by varying pH, Al, and EDTA in chemically defined media. Free Al ion concentration increased as pH and EDTA concentration decreased. Free trace metal ion concentration decreased as EDTA levels increased but increased by orders of magnitude upon addition of Al. pH had an overriding species specific effect on growth rate; at low pH A. ralfsii had higher growth rates than A. formosa and vice versa at high pH. For both species higher EDTA levels depressed growth rates. Moderate additions of Al generally resulted in growth stimulation. The growth rate stimulations, especially at 200 and 400 μg L −1 Al additions, correlate to increases in free trace metal ion concentrations. The EDTA-AI interaction effects on growth rate were both pH and concentration dependent: at pH 7 both species were stimulated by addition of Al at all EDTA levels (except A. ralfsii at 5.0 mM EDTA and A. formosa at 0.5 mNM EDTA); at pH 6 Al addition either stimulated or had no effect on the growth rates of both species (except at low EDTA and high Al levels); at pH 5 A. formosa did not grow and additions of 200 μg L −1 Al stimulated growth of A. ralfsii . It is likely that the effect of pH, Al, and EDTA on speciation of essential or toxic trace metals affects growth rates of these diatoms in a species specific manner.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43905/1/11270_2004_Article_BF00282626.pd

Periphyton community response to localized copper inputs from an artificial substrate.

http://deepblue.lib.umich.edu/bitstream/2027.42/53605/1/2040.pdfDescription of 2040.pdf : Access restricted to on-site users at the U-M Biological Station

ROLE OF ALUMINUM AND GROWTH RATE ON CHANGES IN CELL SIZE AND SILICA CONTENT OF SILICA-LIMITED POPULATIONS OF ASTERIONELLA RALFSII VAR. AMERICANA (BACILLARIOPHYCEAE) 1

Changes in cell size and silica content were examined in response to aluminum additions in cultures of the acidophilic diatom Asterionella ralfsii var. americana KÖrn at pH 6.0. The effects of Al were examined over a range of steady-state growth rates using silica-limited semicontinuous cultures (Si:P = 8.0). Additions of ≥ 2.8 Μmol · L −1 total Al decreased mean cell length, total surface area, and biovolume up to 40–50%. The effects of Al were dependent on growth rate with the magnitude of size reduction increasing at higher growth rates. The proportion of small (approximately 15–20 Μm) cell length classes increased relative to large (approximately 50 Μm length) cell length classes when total Al exceeded 2.8 Μmol · L −1 , particularly at higher growth rates. The relationship between cell quota and steady-state growth rate fit a Droop relationship at 0 and 2.8 Μmol·L −1 total Al, but this fit was highly variable in the presence of Al. Cell quotas in the 6.22 Μmol·L −1 total Al treatment were highest at low growth rates; therefore, a Droop relationship was an inappropriate descriptor of growth rate. Cells also became 30–40% more heavily silicified per unit surface area in the presence of Al and at growth rates ≥0.22 day −1 . Although the mechanisms responsible for size reductions in response to Al additions are unclear, the relationship between metal concentration and frustule morphology may be useful as an indicator of Al loading to acidified lakes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65583/1/j.0022-3646.1990.00250.x.pd

Ecological threshold responses in European Lakes and their applicability for the Water Framework Directive (WFD)implementation: synthesis of lakes results from the REBECCA project

Abstract The objective of this synthesis is to present the key messages and draw the main conclusions from the work on lakes in the REBECCA project, pointing out their links to theoretical ecology and their applicability for the WFD implementation. Type-specific results were obtained from analyses of large pan-European datasets for phytoplankton, macrophytes, macroinvertebrates and fish, and indicators and relationships showing the impact of eutrophication or acidification on these biological elements were constructed. The thresholds identified in many of the response curves are well suited for setting ecological status class boundaries and can be applied in the intercalibration of classification systems. Good indicators for phytoplankton (chrysophytes, cyanobacteria) and macrophytes (isoetids and charaphytes) responses to eutrophication were identified, and the level of eutrophication pressure needed to reach the thresholds for these indicators was quantified. Several existing metrics developed for macrophytes had low comparability and need further harmonisation to be useful for intercalibration of classification systems. For macroinvertebrates, a number of metrics developed for rivers turned out to be less useful to describe lake responses to eutrophication and acidification, whereas other species based indicators were more promising. All the biological elements showed different responses in different lake types according to alkalinity and humic substances, and also partly according to depth. Better harmonisation of monitoring methods is needed to achieve better precision in the dose–response curves. Future research should include impacts of hydromorphological pressures and climate change, as well as predictions of timelags involved in responses to reduction of pressures