Nutrient Saturation Research Articles

Trophic cascades mediated by copepods, not nutrient supply rate, determine the development of picocyanobacteria

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 45:207-218 (2006) - doi:10.3354/ame045207 Trophic cascades mediated by copepods, not nutrient supply rate, determine the development of picocyanobacteria Line E. Sundt-Hansen1,5, Yngvar Olsen1, Herwig Stibor2, Mikal Heldal3, Olav Vadstein4,* 1Norwegian University of Science and Technology, Department of Biology, Trondhjem Biological Station, 7491 Trondheim, Norway 2Department of Biology II, Aquatic Ecology Group, Ludwig-Maximilians-Universität München, Karlstrasse 23-25, Grosshaderner Strasse 2, 82152 Planegg, Germany 3University of Bergen, Department of Biology, Jahnebakken 5, 5020 Bergen, Norway 4Norwegian University of Science and Technology, Department of Biotechnology, 7491 Trondheim, Norway 5Present address: Norwegian Institute for Nature Research, Unit of Fish Ecology, Tungasletta 2, 7485 Trondheim, Norway *Corresponding author. Email: olav.vadstein@biotech.ntnu.no ABSTRACT: We studied the effect of nutrient supply rate (resources) and concentrations of copepods (top predator) on picocyanbacteria (PCY) in experimental ecosystems (mesocosms) using gradients of both nutrients and predators. The biomass and production of PCY, and the biomass and predation rates of their predators were determined by epifluorescence microscopy, X-ray microanalysis (XRMA), the 14C method, and cell counting by microscopy. PCY biomass did not change significantly with increased supply of nutrients, but it was positively correlated with copepod biomass. A lack of variation in PCY growth rates, and nutrient saturation of cells as suggested by nutrient analysis and XRMA measurements, indicate that PCY grew close to their maximum growth rate during the experiment. Appendicularia and ciliates were the main predators on PCY when copepod biomass was normal or low, whereas heterotrophic nanoflagellates were significant predators on PCY when copepod biomass was high. Based on a negative effect of copepod biomass on the biomass of PCY predators, we conclude that predation had a stronger effect on the development of PCY than did nutrient supply rate. The only effect of nutrient supply was negative and indirect, implemented through stimulation of predatory ciliates. Copepods had a profound effect by structuring the food web, and thus directly and indirectly regulating the abundances of predators of PCY (top-down control). Therefore, copepods indirectly controlled the abundance of PCY through trophic cascades. KEY WORDS: Trophic cascade · Resource limitation · Nutrients · Ciliates · Appendicularia · Top-down · Bottom-up Full text in pdf format NextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 45, No. 3. Online publication date: December 21, 2006 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2006 Inter-Research.

Parameter sensitivity of a hydrocarbon biodegradation model under uncertainty of permeability

The effects of permeability variability on uncertainty of the results of a hydrocarbon biodegradation model are addressed. The model includes saturated and unsaturated flow, multi-species transport, heat transport, and bacterial-growth processes. A stochastic approach was used in the uncertainty analysis. Sensitivity analyses were conducted, taking into consideration the effects of heterogeneity. The Monte Carlo method was used, with permeability as the input stochastic variable. Results showed that uncertainty increases with time. This can lead to difficulties regarding cleanup decision making such as predicting the timeframe to reach an aquifer cleanup goal. It was not possible to replace the heterogeneous system with a homogeneous one through the use of effective parameters that preserve an equivalent behavior of the two systems. Effective permeability is space and time dependent and also depends on values of bioactivity parameters. The study also emphasized the importance of accurately measuring certain bacterial parameters, namely, maximum substrate uptake rate for degradation and cell yield coefficient. Uncertainties regarding nutrient and oxygen uptake and saturation parameters were less important for the current application.

Effect of enclosure and nutrient enrichment onMicrocystis blooms in Donghu Lake

A nutrient enrichment experiment was conductedin situ in Donghu Lake (30°33'N, 114°23'E), a shallow hypereutrophic lake in Hubei, China through an enclosure(each 2.5×2.5m by 2 m depth) method from July 15 to September 21, 2000. Three duplicated groups, including two treatments and one control, were designed as unfertilized control (C), nitrogen enrichment (N) and phosphorus enrichment (P), and were also compared with neighboring lake water. DenseMicrocystis bloom exclusively dominated in all the enclosures, while no bloom was observed in the lake. All the enclosures had much higher phytoplankton biomass, higher pH values, and higher transparency than the surrounding lake water. Neither nitrogen nor phosphorus addition had significant effect on phytoplankton composition and biomass due to very high nutrient concentration in the lake water. Suitable biological (absence of filter-feeding silver carp and bighead carp) and physical environment (high transparency, high stability and high pH) associate with saturated nutrient concentration contribute to the nuisanceMicrocystis bloom in the enclosures.

Metal toxicity to Chlorella pyrenoidosa assessed by a short-term continuous test

This study presents the metal toxicity as revealed by Chlorella pyrenoidosa using a short-term continuous test and the conventional batch test. Toxicity tests were conducted in a chemostat with a test duration of 1 day. Toxicity data of five different metals (Cd, Pb, Co, Ni, and Zn) derived from the continuous test were compared against results from the conventional batch tests. The batch test is characterized by its saturated nutrient status for algal growth and, on the other hand, the continuous test is conducted at a nutrient-limiting condition simulating more closely to the aquatic field environment. The continuous test consistently yielded smaller EC 50 values, which indicated that alga in the chemostat is approximately four to six times more sensitive than those from the batch culture. Similar phenomena between the two types of tests were observed based on the NOEC values. Compared to literature data (US EPA ECOTOX Database) from the same species of alga, differences in test sensitivity between the batch tests and chemostat technique varied from 9.25 to 160 times. Such distinct differences indicate that current toxicity database may not adequately reflect the impact of various metal toxicants on C. pyrenoidosa. The continuous test method presented herein is a sensitive and rapid assessment technique and, therefore, has a potential for more general applications such as routine checkup for regulatory purposes.

Contamination Levels and Preliminary Assessment of the Technical Feasibility of Employing Natural Attenuation in 5 Priority Areas of Presidente Bernardes Refinery in Cubatão, São Paulo, Brazil

Five priority areas of potential impact by contaminants (API) were investigated at the Presidente Bernardes Refinery in Cubatão, São Paulo, Brazil with the following aims: (i) to identify both organic and inorganic contaminants present in soil and groundwater; (ii) to define the environmental conditions relevant for microbial activity at the site and (iii) to evaluate the feasibility of employing natural attenuation for treatment of the hydrocarbon contamination. One area (API 1) was an uncontrolled landfill, where waste materials from the refinery were deposited between 1954 and 1986, and four areas (API 4, 5, 7 and 11) were located in the operational section of the refinery. Soil contamination by regulated BTEX compounds (benzene, toluene, total xylenes) was restricted to two samples from API 1. Nonregulated ethylbenzene was detected in one soil sample from API 4, one from API 5 and two from API 1. No soil contained regulated PAH above threshold levels. Several nonregulated PAHs were found in 6 soil samples from API 1, 3 soil samples from API 4 and 1 soil sample from API 5. Site soils contained very high aluminium concentrations, but metal contamination was restricted to one soil sample from API 1, which contained nickel above threshold limits. BTEX contamination of groundwater was due mostly to benzene. Of the 17 PAH molecules tested, only naphthalene and 2-methylnaphthalene occurred in groundwater. The sum of total BTEX and total PAH exceeded 200 microg/L in only a few monitoring wells in API 4, 5 and 11 and was always below 2.640 microg/L. Be, Cd, Cr, Cu, Hg, Ni, Se, Ag, Tl and Zn were not detected in groundwater, which was contaminated in a few locations by aluminium (mostly below 1 mg/L), lead (<0.066 mg/L) and arsenic (<0.056 mg/L). S, K, Ca, Mg and Fe were present in groundwater in excess of physiological requirements for microbial growth, but low concentrations of N and P could become growth limiting. However, BTEX were efficiently degraded in saturated and unsaturated zone microcosms and nutrient amendments did not stimulate biodegradation rates measurably. The inorganic carbon pool in groundwater was up to one order of magnitude larger than the organic carbon pool. Total inorganic carbon (TIC) in API groundwater exceeded TIC of clean groundwater by factors of 2 (API 4), 6 (API 5, 7 and 11) or 10 (API 1). Most of the inorganic carbon incorporated into groundwater beneath the refinery originated from biodegradation in the unsaturated soil, which contained a microbiota (10(6) cells/g on average) capable of growth with most of the pure (benzene, toluene, ethylbenzene and xylene) and mixed hydrocarbons tested (diesel oil, gasoline, naphtha, condensate, aromatic residue and fuel oil). A viscous hydrocarbon paste uncovered in API 1 was insoluble in water but dissolved in dichloromethane. Many organic components of this paste were biodegradable as evidenced by weight reduction of the hydrocarbon paste and by the growth of suspended and attached biomass in saturated zone microcosms, where the paste was the only carbon source. This study indicates that monitored natural attenuation may be a technically feasible and efficient means for plume control in API 1, 4 and 5, provided the plumes in API 4 and 5 are not expanding. This technique is not suitable for contaminant reduction in API 11.

FATE OF NITROGEN IN RIPARIAN FOREST SOILS AND TREES: AN15N TRACER STUDY SIMULATING SALMON DECAY

We introduced an 15N-NH4+ tracer to the riparian forest of a salmon-bearing stream (Kennedy Creek, Washington, USA) to quantify the cycling and fate of a late-season pulse of salmon N and, ultimately, mechanisms regulating potential links between salmon abundance and tree growth. The 15N tracer simulated deposition of 7.25 kg of salmon (fresh) to four 50-m2 plots. We added NH4+ (the initial product of salmon carcass decay) and other important nutrients provided by carcasses (P, S, K, Mg, Ca) to soils in late October 2003, coincident with local salmon spawning. We followed the 15N tracer through soil and tree pools for one year. Biological uptake of the 15N tracer occurred quickly: 64% of the 15N tracer was bound in soil microbiota within 14 days, and roots of the dominant riparian tree, western red cedar (Thuja plicata), began to take up 15N tracer within seven days. Root uptake continued through the winter. The 15N tracer content of soil organic matter reached a maximum of approximately 52%, five weeks after the application, and a relative equilibrium of approximately 40% within five months. Six months after the addition, in spring 2004, at least 37% of the 15N tracer was found in tree tissues: approximately 23% in foliage, approximately 11% in roots, and approximately 3% in stems. Within the stems, xylem and phloem sap contained approximately 96% of the tracer N, and approximately 4% was in structural xylem N. After one year, at least 28% of the 15N tracer was still found in trees, and loss from the plots was only approximately 20%. The large portion of tracer N taken up in the fall and reallocated to leaves and stems the following spring provides mechanistic evidence for a one-year-lagged tree-growth response to salmon nutrients. Salmon nutrients have been deposited in the Kennedy Creek system each fall for centuries, but the system shows no evidence of nutrient saturation. Rates of N uptake and retention are a function of site history and disturbance and also may be the result of a legacy effect, in which annual salmon nutrient addition may lead to increased efficiency of nutrient uptake and use.

Cell Distribution Profiles in Three‐Dimensional Scaffolds with Inverted‐Colloidal‐Crystal Geometry: Modeling and Experimental Investigations

Limited ingrowth of stromal cells is observed when a three-dimensionally ordered scaffold possessing inverted-colloidal-crystal geometry is used to culture adherent cells. In this work, a computational model explaining, as well as predicting, experimental cell distributions is developed. It incorporates a modified Contois cell-growth model that includes the effects of nutrient saturation, competitive product inhibition, and cell-contact inhibition to describe the scaffold-cell system. Our results agree with the hypothesis that the rapid growth of cells on the surface of the scaffold depletes the nutrient supply to the core, resulting in the preferential growth on the exterior of the scaffold. When the cells are cultured in a scaffold subjected to a uniform velocity field, they penetrate to a greater extent into the scaffold core. Alternative seeding and culture strategies are suggested and evaluated.

水溶性ポリマー生産微生物を用いたＭＥＯＲにおける油層内挙動と石油増進回収機構に関するシミュレーション研究

Our research group has carried out experimental studies to analyze the performance and the mechanism of MEOR with TU-15A, a microbe that produces water-soluble polymer. In the previous study, a mathematical model for this MEOR was developed, including almost all important phenomena such as growth and death of microbe, consumption of nutrient, production of water-soluble polymer, increase of water viscosity and the flow of reservoir fluids.In this study, the validity of the MEOR simulation model was firstly examined by comparison between experimental and computed results. The results of the numerical simulation agreed with the experimental results in terms of oil recovery, injection pressure, oil cut and flow profile of injection water.Next, numerical simulation was carried out to analyze the performance and mechanism of this MEOR process for five-spot pattern flooding. The procedure and the conditions used are as follows.Step 1: Conduct water flooding until water cut becomes 90%.Step 2: Inject microbe and nutrient solution into reservoir up to 0.1 PV.Step 3: Shut-in and wait for cultivation in the reservoir for 10 days.Step 4: Conduct postflash until water cut becomes 95%.The quantitative changes of microbe, nutrient, water viscosity and oil saturation were analyzed. Regarding the alteration of flow pattern in the reservoir, it was found that (1) the water-soluble polymer produced by the microbe flowed into the main flow channel along the shortest way between the injection well and the production well and water viscosity there increased, (2) subsequently more uniform flow profile of injected water for oil recovery was established, and (3) then the residual oil was mobilized to the production well. The more than 10% additional oil recovery was obtained in the early phase of postflash in this MEOR process compared with waterflooding.

On the theory of advective effects on biological dynamics in the sea. II. Localization, light limitation, and nutrient saturation

The theory of advective effects is extended to include localization effects, due both to the attenuation of light with depth in the ocean and to nutrient transport into the euphotic zone of finite duration in time and/or over a limited horizontal domain. Nutrient uptake is also generalized to nonlinear Michaelis–Menten kinetics. The characteristic curves are solved for explicitly, and a symbolic general solution is obtained for arbitrary biological dynamics. Some exemplary results are presented for the effect of light, nutrient, and grazing limitations on primary productivity in an NPZ –model. The theory is now applicable to further studies of more realistic oceanic processes.

Physiological and morphological responses to shade and nutrient additions of Claytonia virginica (Portulacaceae): implications for the "vernal dam" hypothesis

Because of their unique phenology and physiology, spring ephemeral herbs are believed to play an important role in intrasystem nutrient cycling in deciduous forest ecosystems. It was hypothesized that they function as a "vernal dam" by temporarily sequestering nutrients and preventing leaching from the system during a period of high nutrient availability. However, spring ephemerals require high-irradiance growing conditions. How do their physiological and morphological responses to ambient light and shade limit their ability to sequester excess nutrients? We performed field experiments using Claytonia virginica L. as a model to test several responses to shade and increasing levels of nutrient additions. We also examined the biomass responses and nutrient storage capacities of other spring ephemeral herbs. In C. virginica, shading reduced ribulose 1,5-bisphosphate carboxylase-oxygenase (Rubisco) activity, photosynthesis rate, specific leaf weight, leaf width/length (W/L), and biomass; nutrient additions increased W/L and biomass only under unshaded conditions. Other herbs responded similarly but reached maximum biomass at lower nutrient addition levels than C. virginica. Shading reduced and nutrient additions increased nitrogen and phosphorus concentrations in both C. virginica and other herbs. Shaded herbs generally reached nutrient saturation at lower nutrient addition levels than unshaded herbs. Overall, unshaded plants sequestered larger amounts of nutrients than shaded plants. This pattern is best explained by a reduction in biomass under shaded conditions. We concluded that C. virginica and other spring herbs, although important components in forest nutrient cycling in the early spring, are limited in their capacity to store excess nutrients, particularly when shaded.Key words: Claytonia virginica, nutrient cycling, spring ephemerals, vernal dam.

Steady-states of semicontinuous cultures of a marine diatom: Effect of saturating nutrient concentrations

The evolution of nitrogen incorporation, the C–N ratio and chlorophyll content were studied in semicontinuous, light–dark synchronised cultures of the marine diatom Phaeodactylum tricornutum Bohlin, maintained under conditions of limiting to highly saturating nutrient concentrations and at different dilutions. The behaviour of cultures diverged from the expected since a decrease in the nitrogen cellular quota and a stable chlorophyll a–C ratio was recorded under nutrient-sufficient conditions, indicating that current theories on continuous cultures cannot be applied directly to semicontinuous cultures when maintained under highly nutrient-saturated conditions.

Comparison of the relative toxicity relationships based on batch and continuous algal toxicity tests

In this study, we compare individual and combined responses of metal toxicants, on Selenastrum capricornutum, using batch and continuous techniques. The batch test is characterized by its saturated nutrient status for algal growth and, on the other hand, the continuous test is conducted at a nutrient-limiting condition. The two test methods depict completely different relationships in relative toxicity. In addition, the batch tests seriously underestimate the toxicity of metal mixtures containing lead. The above phenomena can be attributed to the surplus amounts of a limiting nutrient (phosphorus) and chelators in the growth medium. Since algae in the field are grown under low concentrations of nutrients and chelators, the results presented herein suggest that the significance and adequacy of current algal toxicity test protocols should be carefully reviewed.

Growth and physiological responses of three seagrass species to elevated sediment nutrients in Moreton Bay, Australia

Seagrasses, marine angiosperms with high rates of primary productivity, are often limited by the supply of nutrients, particularly nitrogen (N) and phosphorus (P). We investigated growth and physiological responses of three seagrass species ( Halodule uninervis (Forsk.), Zostera capricorni Aschers and Cymodocea serrulata (r.Br.) Aschers) to elevated sediment N (100 × control) and/or P (10 × control) in adjacent monospecific beds over a 3 month period from spring to early summer. Each species exhibited different growth and biomass responses to both N and P additions. Halodule uninervis growth and biomass increased in response to N and N + P additions, indicative of exclusive N limitation of growth. In contrast, growth and biomass of Z. capricorni increased in response to N + P additions only, indicative of balanced N and P limitation. Cymodocea serrulata growth and biomass were not affected by any of the nutrient additions. Physiological characteristics (amino acid composition, tissue nutrient content, δ 15N) of all three seagrass species responded to N additions (+ N and N + P). Total amino acid content of seagrass leaves increased by 2 to 4 fold in N additions compared with controls. Concentrations of the N-rich amino acids, glutamine and asparagine, increased by 10–1000 fold in N additions, suggesting that these amino acids may be a metabolic storage for N. Tissue N content of leaves. roots and rhizomes increased and δ 15N of the leaves decreased in response to N additions. Although seagrass growth and biomass responses to nutrient additions were species specific, metabolic responses were similar for all species. This suggests physiological characteristics of seagrasses are useful for identifying saturating nutrient supply to an environment, but should not be used to determine whether nutrient availability is limiting the seagrass growth rate.

Organic Matter Dynamics in the West Fork of Walker Branch, Tennessee, USA

Previous articleNext article No AccessStream Organic Matter BudgetsOrganic Matter Dynamics in the West Fork of Walker Branch, Tennessee, USAP. J. MulhollandP. J. Mulholland Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 16, Number 1Mar., 1997 Article DOIhttps://doi.org/10.2307/1468235 Views: 7Total views on this site Citations: 17Citations are reported from Crossref Journal History This article was published in the Journal of the North American Benthological Society (1986-2011), which is continued by Freshwater Science (2012-present). Copyright 1997 The North American Benthological SocietyPDF download Crossref reports the following articles citing this article:J. David Allan, Maria M. Castillo, Krista A. Capps Detrital Energy and the Decomposition of Organic Matter, (Mar 2021): 177–224.https://doi.org/10.1007/978-3-030-61286-3_7Florian Caillon, Jakob Schelker Dynamic transfer of soil bacteria and dissolved organic carbon into small streams during hydrological events, Aquatic Sciences 82, no.22 (Mar 2020).https://doi.org/10.1007/s00027-020-0714-4Jesús Pozo, Arturo Elosegi Coarse Benthic Organic Matter, (Jul 2020): 29–35.https://doi.org/10.1007/978-3-030-30515-4_4Astrid Harjung, Elisabet Ejarque, Tom Battin, Andrea Butturini, Francesc Sabater, Masumi Stadler, Jakob Schelker Experimental evidence reveals impact of drought periods on dissolved organic matter quality and ecosystem metabolism in subalpine streams, Limnology and Oceanography 64, no.11 (Aug 2018): 46–60.https://doi.org/10.1002/lno.11018Ryan A. McManamay, Matthew J. Troia, Christopher R. DeRolph, Arlene Olivero Sheldon, Analie R. Barnett, Shih-Chieh Kao, Mark G. Anderson, Steven Arthur Loiselle A stream classification system to explore the physical habitat diversity and anthropogenic impacts in riverscapes of the eastern United States, PLOS ONE 13, no.66 (Jun 2018): e0198439.https://doi.org/10.1371/journal.pone.0198439Jeremy M. Alberts, Jake J. Beaulieu, Ishi Buffam Watershed Land Use and Seasonal Variation Constrain the Influence of Riparian Canopy Cover on Stream Ecosystem Metabolism, Ecosystems 20, no.33 (Sep 2016): 553–567.https://doi.org/10.1007/s10021-016-0040-9Scott C. Brooks, Craig C. Brandt, Natalie A. Griffiths Estimating uncertainty in ambient and saturation nutrient uptake metrics from nutrient pulse releases in stream ecosystems, Limnology and Oceanography: Methods 15, no.11 (Oct 2016): 22–37.https://doi.org/10.1002/lom3.10139Natalie A. Griffiths and Scott D. Tiegs Organic-matter decomposition along a temperature gradient in a forested headwater stream, Freshwater Science 35, no.22 (Feb 2016): 518–533.https://doi.org/10.1086/685657Natalie A. Griffiths, Jennifer L. Tank, Todd V. Royer, Thomas J. Warrner, Therese C. Frauendorf, Emma J. Rosi-Marshall, Matt R. Whiles Temporal variation in organic carbon spiraling in Midwestern agricultural streams, Biogeochemistry 108, no.1-31-3 (Mar 2011): 149–169.https://doi.org/10.1007/s10533-011-9585-zE. S. Kane, E. F. Betts, A. J. Burgin, H. M. Clilverd, C. L. Crenshaw, J. B. Fellman, I. H. Myers-Smith, J. A. O'Donnell, D. J. Sobota, W. J. Van Verseveld, J. B. Jones Precipitation control over inorganic nitrogen import-export budgets across watersheds: a synthesis of long-term ecological research, Ecohydrology 1, no.22 (Jan 2008): 105–117.https://doi.org/10.1002/eco.10HOLLY L. MENNINGER, MARGARET A. PALMER Herbs and grasses as an allochthonous resource in open-canopy headwater streams, Freshwater Biology 52, no.99 (Sep 2007): 1689–1699.https://doi.org/10.1111/j.1365-2427.2007.01797.xVicenç Acuña,* Adonis Giorgi,† Isabel Muñoz,‡ Francesc Sabater,§ and Sergi Sabater∥ Meteorological and riparian influences on organic matter dynamics in a forested Mediterranean stream, Journal of the North American Benthological Society 26, no.11 (Jul 2015): 54–69.https://doi.org/10.1899/0887-3593(2007)26[54:MARIOO]2.0.CO;2Salvador Mollá, Santiago Robles, Carmen Casado Seasonal Variability of Particulate Organic Matter in a Mountain Stream in Central Spain, International Review of Hydrobiology 91, no.55 (Oct 2006): 406–422.https://doi.org/10.1002/iroh.200510857Mark S. Johnson, Johannes Lehmann, Evandro Carlos Selva, Mara Abdo, Susan Riha, Eduardo Guimarães Couto Organic carbon fluxes within and streamwater exports from headwater catchments in the southern Amazon, Hydrological Processes 20, no.1212 (Jan 2006): 2599–2614.https://doi.org/10.1002/hyp.6218Jon Molinero, Jesus Pozo Impact of a eucalyptus (Eucalyptus globulus Labill.) plantation on the nutrient content and dynamics of coarse particulate organic matter (CPOM) in a small stream, Hydrobiologia 528, no.1-31-3 (Oct 2004): 143–165.https://doi.org/10.1007/s10750-004-2338-4Lara A. Martin,* Patrick J. Mulholland, Jackson R. Webster, and H. Maurice Valett Denitrification potential in sediments of headwater streams in the southern Appalachian Mountains, USA, Journal of the North American Benthological Society 20, no.44 (Jul 2015): 505–519.https://doi.org/10.2307/1468084John F. McCarthy, George R. Southworth, Kenneth D. Ham, Jennifer A. Palmer Time-integrated, flux-based monitoring using semipermeable membrane devices to estimate the contribution of industrial facilities to regional polychlorinated biphenyl budgets, Environmental Toxicology and Chemistry 19, no.22 (Feb 2000): 352–359.https://doi.org/10.1002/etc.5620190215

Anaerobic digestion of municipal solid waste

Tuna processing wastes (sludges high in fat, oil, and grease [FOG]) and municipal solid waste (MSW) generated on Tutuila Island, American Samoa, represent an ongoing disposal challenge. The biological conversion of the organic fraction of these wastes to useful products, including methane and fertilizer-grade residue, through anaerobic high-solids digestion is currently in scale-up development. The suitability of the anaerobic digestion residues as a soil amendment was evaluated through extensive chemical analysis and greenhouse studies using corn as an indicator crop. Additionally, native Samoan soil was used to evaluate the specific application rates for the compost. Experiments established that anaerobic residues increase crop yields in direct proportion to increases in the application rate. Additionally, nutrient saturation was not demonstrated within the range of application rates evaluated for the Samoan soil. Beyond nutrient supplementation, organic residue amendment to Samoan soil imparts enhanced water- and nutrient-binding capacities.

The ground beetle (Coleoptera: Carabidae) fauna of welsh peatland biotopes: Factors influencing the distribution of ground beetles and conservation implications

Over the three years 1987–1989, a large-scale survey of carabid beetles (Coleoptera: Carabidae) was carried out in a total of 300 trapping stations set up in 118 peatland sites throughout Wales, UK. Factors influencing the distribution of carabid beetles in Welsh peatland habitats were investigated using the ordination program DECORANA. The most important factors identified were nutrient status and saturation of the substrate, altitude and grazing by stock animals; a further significant factor, burning of the site, could not be investigated thoroughly because of insufficient data. Implications of the results in the conservation management of peatlands are discussed.

Variation in growth rates of submerged rooted macrophytes

Above-ground growth rates of 14 temperate, submerged freshwater macrophytes were measured in the laboratory at high dissolved inorganic carbon levels (3.3-3.8 mM), nutrient saturation and photon flux densities (phoosynthetically active radiation (PAR) of 14.4 mol m −2 day −1 at 15°C. Growth rates ranged from 0.007 to 0.109 day −1, corresponding to doubling times of 95 and 6.4 days. Growth rates of selected species measured at low shoot densities in the field during summer resembled the laboratory rates. The carbon affinity during photosynthesis accounted for 61% of the observed variability in growth rates. These results support previous findings demonstrating the importance of carbon utilization for the distribution, abundance and growth of submerged macrophytes. The carbon affinity was a constant attribute for some species, including the slowly growing rosette species, but changed during acclimatization in the laboratory for other species. Morphological features (e.g. the surface/volume ratio) were unable to account for much of the variability in growth rates.

GROWTH AND MORPHOLOGY OF YOUNG GAMETOPHYTES OF PORPHYRA ABBOTTAE (RHODOPHYTA): EFFECTS OF ENVIRONMENTAL FACTORS IN CULTURE1

ABSTRACTGrowth, blade shape and blade thickness of young gametophytes of Porphyra abbottae Krishnamurthy cultured from conchospores were determined at various combinations of temperature (8, 10, 12° C), photon flux density (17.5, 70, 140 μmol·m‐−2·S−1), nutrient concentration (5, 25, 50, 100% f medium) and water motion (0, 50, 100, 150 rpm). Growth (as surface area) was light‐saturated at 70 μmol· m−2· S−1, light‐inhabited at 140 μmol·m−2· S−1, and nutrient‐saturated an 25% f medium. Temperature had no significant effect on growth. Water motion and nutrients had an interactive effect on growth, with water motion having the greatest effect at the lowest nutrient concentrations. Water motion enhanced growth even at saturating nutrient concentrations.Blade length / width ratio was greater in low light (2.5) than in saturating light (1.9); with increasing water motion the ratio increased from 1.2 to 2.4. Blade thickness (53‐88 μm) was greatest at the highest nutrient concentrations and at the lowest water motion levels. Temperature and light did not have a consistent effect on blade thickness.

Susceptibility of U.S. Estuaries to Pollution

Utilizing data primarily from the U.S. Department of Commerce, both estuaries and watersheds for 78 U.S. systems are analyzed. Watersheds are classified according to total population and discrete subpopulations. The Vollenweider approach, which compares hydraulic loading to nutrient loading of lakes, is adapted to estuaries. By considering total population as a surrogate of point source nutrients, agricultural workers as a surrogate of non-point source toxics and nutrients and chemical + metal workers as a surrogate of point source toxics, we can estimate potential anthropogenic impacts on watersheds. When these surrogates are plotted against hydraulic loading, managers have a tool to identify estuaries most likely to be under greatest anthropogenic presaure. The estuaries with highest susceptibility from total population, as well as the estuaries with the the highest susceptibility to toxic stress, are identified. On a Vollenweider diagram, the phosphorous loadings of freshwater bodies are plotted as a function of hydraulic loading. The permissible-excessive phosphorous loadings have been both theoretically and empirically determined. We have replotted the freshwater data and added 33 U.S. estuary P loadings that were previously unavailable. Estuaries plot on the Vollenweider diagram as a continuum of fresh waterbodies, both in terms of hydraulic loading and phosphorus loading. Most estuaries appear to have permissible P loadings. Analysis of nutrient loading (normalized to hydraulic loading) versus water quality parameters like chlorophyll a indicates that estuaries are more efficient users of nutrients than are freshwater bodies, and that they reach a “nutrient saturation point”. Perhaps this is due to grazing or turbidity. It appears that, in general, the OECD eutrophication modeling approach is applicable to estuarine systems as well as lakes and impoundments.

Nutrient Status of Phytoplankton Blooms in Norwegian Waters and Algal Strategies for Nutrient Competition

During blooms in Norwegian waters phytoplankton communities are phosphorus limited in fresh and brackish waters, and balanced or even nitrogen limited in high-salinity marine waters. This results from the high N/P ratio for available nutrients before onset of blooms in freshwater relative to seawater (N/P (atoms) &gt;100 and 12–16, respectively). Algal N/P ratios at nutrient saturation vary between 8 and 27 among species, and average 16. A low ratio at nutrient saturation may imply P limitation even in high-salinity waters (e.g. Skeletonema costatum). In general, nutrient deficiency becomes more pronounced as the biomass increases. Addition of sewage shifts natural systems toward N limitation, which may therefore be a secondary effect of accelerated eutrophication. interspecific competition in nutrient-limited communities depends on the nutrient requirement of individual species and the mode of nutrient uptake. In our example the desmid Staurastrum luetkemuellerii outcompetes the cyanobacterium Microcystis aeruginosa in a chemostat when the nutrient supply is continuous; the opposite happens when nutrient supply is pulsed.