Periphyton response to long-term nutrient enrichment in a shaded headwater stream

2005 ◽  
Vol 62 (9) ◽  
pp. 2033-2045 ◽  
Author(s):  
Jennifer L Greenwood ◽  
Amy D Rosemond
Keyword(s):  
Growth Rates ◽  
Nutrient Enrichment ◽  
Algal Species ◽  
Light Availability ◽  
Algal Growth ◽  
Detectable Effect ◽  
Long Term Effects ◽  
Tree Canopies ◽  
Periphyton Biomass

We maintained elevated but moderate concentrations of nitrogen and phosphorus continuously for 2 years in a heavily shaded headwater stream and compared effects on stream periphyton with a reference stream. Both streams were sampled for 1 year before treatment. Some measures of periphyton biomass (ash-free dry mass and chlorophyll a) responded positively to enrichment. Increased chlorophyll a was likely a result of higher chlorophyll per cell, as total algal biovolume did not change with enrichment. These differences were greatest during high-light months (November-May), when cellular growth rates (a proxy for production) were also highest with enrichment. Algal assemblages were dominated by diatoms and remained similar between the treatment and reference streams throughout the enrichment period. Although nutrients stimulated algal growth rates, the long-term effects of nutrient addition on periphyton biomass were small in magnitude compared with other published values and were potentially suppressed by light availability and invertebrate consumption. These and other factors may have also been important in limiting the algal species pool and thus a taxonomic response to enrichment. Our results indicate that in headwater streams with intact tree canopies, chronic nutrient enrichment at moderate concentrations may have little detectable effect on benthic algal composition or periphyton biomass. Although nutrients stimulated algal growth rates, the long-term effects of nutrient addition on periphyton biomass were small in magnitude compared with other published values and were potentially suppressed by light availability and invertebrate consumption. These and other factors may have also been important in limiting the algal species pool and thus a taxonomic response to enrichment. Our results indicate that in headwater streams with intact tree canopies, chronic nutrient enrichment at moderate concentrations may have little detectable effect on benthic algal composition or periphyton biomass.

scholarly journals Long‐term effects of nutrient enrichment controlling plant species and functional composition in a boreal rich fen

2018 ◽  
Vol 29 (5) ◽  
pp. 907-920 ◽  
Author(s):  
Dag‐Inge Øien ◽  
Bård Pedersen ◽  
Łukasz Kozub ◽  
Klara Goldstein ◽  
Mateusz Wilk
Keyword(s):  
Plant Species ◽  
Nutrient Enrichment ◽  
Functional Composition ◽  
Long Term Effects ◽  
Rich Fen

scholarly journals Rapid multi-generational acclimation of coralline algal reproductive structures to ocean acidification

2021 ◽  
Vol 288 (1950) ◽  
Author(s):  
B. Moore ◽  
S. Comeau ◽  
M. Bekaert ◽  
A. Cossais ◽  
A. Purdy ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Growth Rates ◽  
Natural Habitat ◽  
Algal Growth ◽  
Coralline Algae ◽  
Reproductive Structures ◽  
Highly Sensitive ◽  
Negative Effect ◽  
Coral Reef Ecosystems

The future of coral reef ecosystems is under threat because vital reef-accreting species such as coralline algae are highly susceptible to ocean acidification. Although ocean acidification is known to reduce coralline algal growth rates, its direct effects on the development of coralline algal reproductive structures (conceptacles) is largely unknown. Furthermore, the long-term, multi-generational response of coralline algae to ocean acidification is extremely understudied. Here, we investigate how mean pH, pH variability and the pH regime experienced in their natural habitat affect coralline algal conceptacle abundance and size across six generations of exposure. We show that second-generation coralline algae exposed to ocean acidification treatments had conceptacle abundances 60% lower than those kept in present-day conditions, suggesting that conceptacle development is initially highly sensitive to ocean acidification. However, this negative effect of ocean acidification on conceptacle abundance disappears after three generations of exposure. Moreover, we show that this transgenerational acclimation of conceptacle development is not facilitated by a trade-off with reduced investment in growth, as higher conceptacle abundances are associated with crusts with faster growth rates. These results indicate that the potential reproductive output of coralline algae may be sustained under future ocean acidification.

Silicon Contamination in Diatom Nutrient Enrichment Experiments

1983 ◽  
Vol 40 (5) ◽  
pp. 657-664 ◽  
Author(s):  
Stephen J. Tarapchak ◽  
David R. Slavens ◽  
Michael A. Quigley ◽  
Judith S. Tarapchak
Keyword(s):  
Growth Rates ◽  
Nutrient Enrichment ◽  
Lake Michigan ◽  
Pyrex Glass ◽  
Short Term ◽  
Photosynthetic Rates ◽  
Nutrient Bioassay ◽  
Enrichment Experiments ◽  
Silicon Contamination

Large amounts of biologically available silicon (Si) were released into solution from the walls of Pyrex glass reagent bottles and Erlenmeyer flasks during nutrient bioassay experiments using Lake Michigan water. Photosynthetic rates in short-term (4–7 h) incubations and diatom growth rates and maximum yields in long-term incubations (~7 d) were affected by these extraneous Si supplies. The results of conventional nutrient enrichment bioassays performed in low-Si environments can be seriously biased unless Si contamination from glass incubation containers is avoided.

Algal Growth and Primary Productivity in a Thermal Stream

1968 ◽  
Vol 25 (10) ◽  
pp. 2037-2058 ◽  
Author(s):  
John G. Stockner
Keyword(s):  
Primary Production ◽  
Growth Rates ◽  
Hot Springs ◽  
Hot Spring ◽  
Morphological Changes ◽  
Gross Primary Production ◽  
Standing Stock ◽  
Algal Species ◽  
Algal Growth ◽  
Algal Mat

Estimates of primary production and respiration of cyanophycean algal species growing in the run-off stream of a hot spring (37 C) were obtained throughout 1966 using the diurnal oxygen curve technique. Rates of gross primary production were slightly higher than published values from other aquatic ecosystems, but were less than recent estimates from hot springs in Yellowstone and Mount Lassen National Parks using the C14 uptake method. Production/respiration ratios were calculated and ranged from 1.1 to 5.0. The effect of photosynthesis on the ionic concentration of influent and effluent water was noted, together with morphological changes in the algal mat as the growing season progressed. Changes in algal standing stock were studied in 1964 and 1965, together with growth rates from denuded areas by two methods of harvest. In both years the most rapid growth was recorded in May and June, whereas during the winter months growth was negligible. Maximum values of primary production in May and June 1966 coincided with these maximum growth periods. Significant differences in growth rates between years were thought to be due to several factors; most notably, harvest methods and auto-inhibitory toxins produced by layers of senescent cells composing the "mature" algal mat. Energy losses due to algal export and grazing are discussed in relation to the dynamics of the mat, and an annual energy budget is derived from estimates obtained in 1966.

Periphyton biomass response to changing phosphorus concentrations in a nutrient-impacted river: a new methodology for phosphorus target setting

2007 ◽  
Vol 64 (2) ◽  
pp. 227-238 ◽  
Author(s):  
Michael J Bowes ◽  
Jim T Smith ◽  
John Hilton ◽  
Michael M Sturt ◽  
Patrick D Armitage
Keyword(s):  
Nutrient Enrichment ◽  
Algal Biomass ◽  
Algal Growth ◽  
Physical Effect ◽  
Target Setting ◽  
Knowledge Based ◽  
P Limitation ◽  
Periphyton Biomass ◽  
P Addition ◽  
Biomass Reduction

Nutrient modification experiments were conducted in streamside flumes to determine the concentration at which P limits algal growth in the mesotrophic River Frome, Dorset, UK. The soluble reactive P (SRP) concentration in each flume was either increased (by P addition), decreased (by precipitating P with iron(II) sulphate solution), or left unaltered (control), producing SRP concentrations ranging from 32 to 420 µ·L–1. Increasing the ambient SRP concentration did not increase epilithic algal growth, showing that the River Frome was not P limited at 109 µ SRP·L–1. In the P-stripped flumes, algal biomass declined as the SRP concentration fell below ~90 µ·L–1, with a 60% biomass reduction at <40 µ SRP·L–1. Phosphorus-diffusing periphytometers deployed in the P-stripped flumes confirmed that reduced rates of algal growth were due to P limitation rather than a physical effect of FeSO4 addition. The ~90 µ·L–1 maximum P-limiting concentration is likely to be similar for comparable nutrient-impacted rivers. This iron-stripping approach expands the existing river nutrient-enrichment methodology so that it can be used in nutrient-impacted rivers and should allow catchment managers to produce knowledge-based P reduction targets prior to introducing remediation.

Spring isothermal mixing in the Great Lakes: evidence of nutrient limitation and nutrient-light interactions in a suboptimal light environment

2000 ◽  
Vol 57 (9) ◽  
pp. 1901-1910 ◽  
Author(s):  
G L Fahnenstiel ◽  
R A Stone ◽  
M J McCormick ◽  
C L Schelske ◽  
S E Lohrenz
Keyword(s):  
Great Lakes ◽  
Growth Rates ◽  
Nutrient Enrichment ◽  
Light Availability ◽  
Light Limitation ◽  
Phytoplankton Communities ◽  
Growth Irradiance ◽  
Enrichment Experiments ◽  
Isothermal Mixing

During the spring isothermal mixing period (April-May) in 1993-1995, photosynthesis-irradiance and growth-irradiance experiments were conducted in Lakes Erie, Huron, Michigan, and Ontario to assess light limitation. Additionally, nutrient enrichment experiments were conducted in Lake Ontario. Results from the photosynthesis-irradiance experiments suggested that phytoplankton communities in all the lakes can be either light limited or light saturated, as the threshold parameter (Ik) was similar to mean water column irradiances (mean Iwc, ratio = 1.0). Growth-irradiance experiments also suggested the potential for light saturation; mean daily irradiance exceeded the threshold growth irradiance (Ik,g) in 95% of cases. Growth rates became light saturated at lower irradiances than photosynthetic rates. Evidence for a nutrient-light interaction in controlling in situ growth rates was also found in the nutrient enrichment experiments at incubation irradiances [Formula: see text] mean Iwc. Our results suggest that an interaction between nutrients and light is often controlling phytoplankton growth during spring mixing in the Great Lakes. The role of these nutrient-light interactions has increased in the past decade due to increased light availability in the lower lakes caused by phosphorus load reductions and the filtering activities of nonindigenous mussels.

scholarly journals Short- and long-term effects of nutrient enrichment on microbial exoenzyme activity in mangrove peat

2015 ◽  
Vol 81 ◽  
pp. 38-47 ◽  
Author(s):  
Joost A. Keuskamp ◽  
Ilka C. Feller ◽  
Hendrikus J. Laanbroek ◽  
Jos T.A. Verhoeven ◽  
Mariet M. Hefting
Keyword(s):  
Nutrient Enrichment ◽  
Long Term Effects ◽  
Short And Long Term ◽  
Mangrove Peat

Long-term effects on cowpea plant growth of a short-term cowpea aphid infestation

1986 ◽  
Vol 64 (8) ◽  
pp. 1727-1732 ◽  
Author(s):  
C. D. B. Hawkins ◽  
M. I. Whitecross ◽  
M. J. Aston
Keyword(s):  
Compensatory Growth ◽  
Detectable Effect ◽  
Long Term Effects ◽  
Aphid Infestation ◽  
Relative Growth Rates ◽  
Unit Leaf ◽  
Aphis Craccivora Koch ◽  
Experimental Treatments ◽  
Induced Changes

Two-week-old cowpea seedlings (Vigna unguiculata (L.) Walp.) were infested with cowpea aphids (Aphis craccivora Koch (Homoptera: Aphididae)) for 5, 10, 15, and 20 days at which time the aphids were removed with a systemic insecticide. The seedlings were then allowed to grow for another 3 months. By day 10, plant dry weights, mean relative growth rates [Formula: see text], and mean unit leaf rates (Ē) were all significantly reduced in the infested plants, and these relationships still held at day 20. Apparent decreases in photosynthesis and (or) increases in respiration were the primary causes of these reductions. There were no significant differences between control and experimental treatments for [Formula: see text] calculated from day 0, and total number of seeds and seed pods produced at the end of the study. Control plants had significantly more mature seed pods and seeds, while formerly infested plants had significantly more mature and unripe seeds per pod, more unripe seed pods and seeds produced, and greater values for [Formula: see text] from the time of aphid removal until the end of the experiment. This latter increase in [Formula: see text] indicates a form of compensatory growth. It is proposed that the compensatory growth of previously infested plants and ultimate similarity in seed production, as compared with control plants, may have resulted from aphid-induced changes via nonhormonal compounds acting as phytohormone regulators. The different durations of aphid infestation used had no detectable effect on long-term growth.

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