The Role of Fishes in the Regulation of Phosphorus Availability in Lakes

1980 ◽  
Vol 37 (10) ◽  
pp. 1540-1549 ◽  
Author(s):  
Brian S. Nakashima ◽  
William C. Leggett
Keyword(s):  
Total Phosphorus ◽  
Yellow Perch ◽  
Fish Community ◽  
Nutrient Dynamics ◽  
Feeding Habits ◽  
Nutrient Release ◽  
Open Water ◽  
Fish Tissue ◽  
Fecal Phosphorus

Several hypotheses concerning the contribution of fishes to nutrient dynamics in lakes were examined. The maximum quantity of excreted phosphorus by fishes was found to be negligible (< 0.33%) when compared to the demand for this element by the seston. Zooplankton (cladocerans and copepods) excretion supplied up to 12% of the daily summer orthophosphate requirements of the seston. The pool of total phosphorus present in the open water fish community was approximately equivalent to that present in the seston while the total phosphorus biomass in zooplankton was only 22 to 40% of that in the seston. Daily incorporation of total phosphorus into fish tissue and losses as fecal phosphorus could constitute up to 40% of total phosphorus in the seston lost due to sedimentation from the epilimnion depending on the feeding habits of the dominant fish species. Nutrient release due to the decomposition of fish carcasses supplied up to 20% of the allochthonous phosphorus entering the south basin in the spring. The prey of the adult fish community is predominantly benthic and littoral in origin. However, the role of predation in structuring benthic and littoral prey populations and its effect on nutrient dynamics is unknown.Key words: budget, excretion, Lake Memphremagog, nutrients, Perca flavescens, yellow perch; phosphorus, population estimate

Diet of the endangered spirlin (Alburnoides bipunctatus) at the centre of its distribution in Europe

2018 ◽  
Vol 69 (11) ◽  
pp. 1712
Author(s):  
L. Marszał ◽  
M. Grzybkowska ◽  
D. Błońska ◽  
J. Leszczyńska ◽  
M. Przybylski
Keyword(s):  
Resource Use ◽  
Diet Composition ◽  
Feeding Habits ◽  
Open Water ◽  
Size Class ◽  
Habitat Segregation ◽  
Chironomid Larvae ◽  
Size Classes ◽  
Taxonomic Groups ◽  
Distribution In Europe

The feeding habits of spirlin Alburnoides bipunctatus were investigated in a tributary of the River Vistula (Poland). To evaluate size-related patterns of resource use, fish were assigned to three size classes, defined according to size at first maturation: small (29–70-mm total length, TL), medium (71–90mm TL) and large (91–104mm TL). There was a significant ontogenetic shift in the feeding pattern among size classes, marked by differences in the proportion of the main taxonomic groups of prey consumed: small spirlin primarily consumed chironomid larvae, whereas medium and large spirlin showed a preference for Coleoptera, Ephemeroptera and imagines of unidentified insects. The proportion of prey taken from the water column was significantly lower for small- than medium- and large-sized spirlin. This difference was attributed to the benthic habits of small spirlin compared with medium and large spirlin. The shift to open water feeding in spirlin corresponded with sexual maturation, with habitat segregation between the smallest size class (comprising juveniles) and larger size classes (mature individuals). Size-specific changes in the diet composition of this species have not previously been documented.

scholarly journals Role of Organic Acids on Phosphorus Fractions in Silty Clay Loam Soil

2018 ◽  
Vol 8 (2) ◽  
pp. 12-21
Author(s):  
Abdulmahdi S.ALansari ◽  
Muhammad M.Yassin ◽  
Mahdi W.Seheib
Keyword(s):  
Humic Acid ◽  
Organic Acids ◽  
Incubation Period ◽  
Total Phosphorus ◽  
Phosphate Fertilizer ◽  
Silty Clay ◽  
Clay Loam ◽  
Silty Clay Loam ◽  
Fertilized Soil

This study was conducted to evaluation the role of the organic acids in the phosphorus fractions in silty clay loam texture. The laboratoryexperiment was conducted by adding the organic acids (Humic acid ,Citric acid ,Oxalic acid , Malic acid ,Acetic acid and Lactic acid )to the fertilized soil with conc. super phosphate fertilizer with 100 kg h-1 level with concentrations (0,15,30,45 and60)mg L-1,except Humic acid (500,1000,1500 and 2000) mg L-1.The soil was incubated at 30 C for 14,28,42,56 and 70 days period and the keep of field capacity about of incubation period during the daily weight.Amount of available ,mineral ,organic and total phosphorus after each incubated period were measured. The results showed that theaddition of organic acids of Humic acid ,Citric acid ,Oxalic acid and Malic acid were caused to increaseamount of available ,mineral ,organic and constant of total phosphorus in fertilized soil with conc. super phosphate fertilizer and increased its amount with increasing of organic acid concentration and better of Humic acid 2000mg L-1 significanton all the treatments .The results of the study that theaddition of organic acids were caused to increase amount of available and mineral phosphorus with increasing of incubation period and constant amount of total phosphorus and decreasing of organic phosphorus amount and available for only soil and only fertilizer treatment during increasing of incubation period .The organic acids can be arranged according to its ability toincrease the availabilityof the phosphorus as follow :

scholarly journals “No me des el pescado, enséñame a pescar” “Do not hand me fish, teach me how to fish” Community Lawyering in Puerto Rico: Promoting empowerment and self-help

2014 ◽  
Vol 12 ◽  
pp. 83
Author(s):  
Myrta Morales-Cruz
Keyword(s):  
Community Development ◽  
Fish Community ◽  
Legal Aid ◽  
Self Help ◽  
Development Section ◽  
The People ◽  
The University ◽  
Insight Into ◽  
Special Meaning

<p>Law 232 of August 27, 2004 has a special meaning to the people residing in some of Puerto Rico's poorest communities. It was the result of the hard work, during a period of a year and a half, of leaders from some of these communities and my students, the students of the community development section of the Legal Aid Clinic of the University of Puerto Rico’s School of Law. The story of Law 232 can provide insight into what the role of a lawyer can be in the battle against poverty. To understand the story of this Puerto Rican law, one has to go back to August of 2002. During that month the University of Puerto Rico's School of Law Legal Aid Clinic inaugurated its community development section.</p>

Preliminary conceptual models of groundwater and nutrient dynamics in typical agricultural river catchments underlain by hard-rock aquifers in Scotland and Northern Ireland: The River Ythan and Upper Bann River Catchments

2021 ◽  
Author(s):  
Hamish Johnson ◽  
Jean-Christophe Comte ◽  
Ulrich Ofterdinger ◽  
Rachel Cassidy ◽  
Mads Troldborg
Keyword(s):  
Northern Ireland ◽  
Nutrient Dynamics ◽  
Conceptual Models ◽  
Nutrient Management ◽  
Hard Rock ◽  
Fate And Transport ◽  
Hard Rock Aquifers ◽  
Groundwater Systems ◽  
River Catchments

&lt;p&gt;The environmental fate and transport of nitrogen and phosphorus nutrient species leached from agroecosystems are largely influenced by the hydrogeological setting, which dictates the distribution of groundwater flow pathways, residence times, and physio-chemical properties of the subsurface. Traditional conceptual models tend to oversimplify these relationships, and their application towards river catchment nutrient management promotes insufficient characterisation of hydrogeological heterogeneity, which is subsequently not accounted for. Until recently, very little hydrogeological information and conceptual understanding existed for groundwater systems within the postglacial basement terranes of Scotland and Northern Ireland, due to an abundance of surface water resources and prevalence of poorly productive bedrock aquifers. Recent research has demonstrated the role of geological heterogeneity in determining the contaminant transport behaviour of these hard-rock aquifers, where the presence of weathering and fracturing can potentially result in the rapid delivery of nutrients to rural water supplies and groundwater-dependent ecosystems.&lt;/p&gt;&lt;p&gt;We aim to further elucidate the role of hydrogeological setting in river catchment nutrient dynamics to improve agricultural sustainability in geologically heterogeneous agricultural regions. This will be achieved by developing conceptual models of nutrient fate and transport for two contrasting agricultural river catchments. Here, we present preliminary conceptual models based on a literature review of groundwater systems within the same geological terranes, analysis of hydrochemical monitoring data, and accounting for catchment-specific features through desk studies of geological and airborne geophysical surveys.&lt;/p&gt;&lt;p&gt;The River Ythan is a groundwater-dominated lowland catchment within Scotland&amp;#8217;s arable belt, designated a Nitrate Vulnerable Zone due to the eutrophication of its estuary. This catchment is geologically complex, with a variably metamorphosed and sheared Precambrian basement with igneous intrusions ranging from ultrabasic rocks to granite. This complexity is enhanced by the significant preservation of Tertiary weathering profiles and an extensive but discontinuous cover of glacial deposits derived from the saprolites. The superficial deposits create a shallow aquifer system characterized by oxic, well-mixed groundwaters with high nitrate concentrations. The bedrock groundwater bodies feature lower nitrate concentrations with variable denitrification rates, resulting from the relationships between lithology, tectonics, and weathering.&lt;/p&gt;&lt;p&gt;Two upland headwater sub-catchments of the Upper Bann River (Co. Down, Northern Ireland) drain either side of the contact between a granodiorite laccolith and Lower Palaeozoic metasedimentary rocks within an elevated drumlinoid landscape. Here, diffuse phosphorus exports to surface waters have not experienced the same extent of decline observed in storm runoff phosphorus following the implementation of nutrient management policies. Anoxic groundwaters favourable for denitrification may result in the release of previously adsorbed (legacy) phosphorus following the reductive dissolution of Fe (hydr)oxides. These conditions are generated by (a) confinement by thick, drumlinised clayey tills; and (b) bedrock structures promoting deep groundwater flow.&lt;/p&gt;&lt;p&gt;The site-specific conceptual models will be further developed through multi-scale geophysical characterisation of hydrogeological heterogeneity and constrained by the catchment-scale distribution of residence times derived from stable (&lt;sup&gt;2&lt;/sup&gt;H, &lt;sup&gt;18&lt;/sup&gt;O) and radioactive (&lt;sup&gt;3&lt;/sup&gt;H) isotope compositions of groundwaters. These refined conceptual models can guide the development of numerical groundwater models and spatially targeted nutrient management.&lt;/p&gt;

scholarly journals The littoral zone of polar lakes: inshore–offshore contrasts in an ice-covered High Arctic lake

2020 ◽  
pp. 1-24
Author(s):  
Paschale N. Bégin ◽  
Milla Rautio ◽  
Yukiko Tanabe ◽  
Masaki Uchida ◽  
Alexander I. Culley ◽  
...  
Keyword(s):  
Light Availability ◽  
Sharp Decrease ◽  
Open Water ◽  
High Arctic ◽  
Early Summer ◽  
Fatty Acid Profiles ◽  
Canadian High Arctic ◽  
Abrupt Increase ◽  
Horizontal Gradients

In ice-covered polar lakes, a narrow ice-free moat opens up in spring or early summer, and then persists at the edge of the lake until complete ice loss or refreezing. In this study, we analyzed the horizontal gradients in Ward Hunt Lake, located in the Canadian High Arctic, and addressed the hypothesis that the transition from its nearshore open-water moat to offshore ice-covered waters is marked by discontinuous shifts in limnological properties. Consistent with this hypothesis, we observed an abrupt increase in below-ice concentrations of chlorophyll a beyond the ice margin, along with a sharp decrease in temperature and light availability and pronounced changes in benthic algal pigments and fatty acids. There were higher concentrations of rotifers and lower concentrations of viruses at the ice-free sampling sites, and contrasts in zooplankton fatty acid profiles that implied a greater importance of benthic phototrophs in their inshore diet. The observed patterns underscore the structuring role of ice cover in polar lakes. These ecosystems do not conform to the traditional definitions of littoral versus pelagic zones but instead may have distinct moat, ice-margin, and ice-covered zones. This zonation is likely to weaken with ongoing climate change.

Role of Environment and Stock on the Elemental Composition of Sockeye Salmon (Oncorhynchus nerka) Vertebrae

1987 ◽  
Vol 44 (6) ◽  
pp. 1206-1212 ◽  
Author(s):  
S. Behrens Yamada ◽  
T. J. Mulligan ◽  
D. Fournier
Keyword(s):  
Elemental Composition ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Fish Tissue ◽  
Fish Food ◽  
X Ray ◽  
Hatchery Fish ◽  
Environmental Component ◽  
Genetic And Environmental Factors

Individual spawning populations, or stocks, of salmon differ in the elemental composition of their scales and bone. These stock-specific differences have a pronounced environmental component, since elevated concentrations of certain elements in fish tissue can be induced by feeding hatchery fish food enriched in these elements. This study tests the hypothesis that both genetic and environmental factors contribute to the stock-specific elemental composition of salmon vertebrae. Four stocks of sockeye salmon (Oncorhynchus nerka) were raised under identical conditions and each stock was subjected to four environmental treatments. The elemental composition of the vertebrae were analysed using X-ray spectroscopy; nine elements were measured. The resulting elemental composition data were analysed by multivariate analysis of variance. Evidence is presented for both a stock and a treatment factor contributing to the vertebral composition.

Microphysical cloud parameters of optically thin clouds in the Arctic in summer 2017

2020 ◽  
Author(s):  
Philipp Richter ◽  
Mathias Palm ◽  
Christine Weinzierl ◽  
Penny Rowe ◽  
Justus Notholt
Keyword(s):  
Aerosol Particles ◽  
Microwave Radiometer ◽  
Arctic Region ◽  
Open Water ◽  
The Arctic ◽  
Arctic Amplification ◽  
Cloud Parameters ◽  
Microphysical Properties ◽  
Infrared Spectrometer

&lt;p&gt;As a precursor of the current MOSAiC campaign, the PASCAL campaign took place in summer 2017 around Svalbard [1]. In the scope of the project (AC)3, infrared radiation emitted by clouds was measured using a calibrated Fourier Transform Infrared Spectrometer (EM-FTIR). EM-FTIR can be used for different purposes, like the observation of trace gases or microphysical cloud parameters (MCP) like cloud optical depths and cloud effective droplet radii. In the observation of MCP, EM-FTIR can be used to measure optically thin clouds with very low amounts of liquid water paths below 30 gm-2, where microwave radiometer face problems because of their larger measuring uncertainty.&amp;#160;&lt;/p&gt;&lt;p&gt;The retrieval of the MCP is performed using the newly introduced retrieval code CLARRA [2]. CLARRA shows a high accuracy in the retrieval of MCP from low-level clouds, which were often observed during the measurements.&amp;#160;&lt;/p&gt;&lt;p&gt;The measurements were performed between June 2017 and August 2017 around Svalbard and include measurements of clouds over sea ice and open water. The spatial distribution of the MCP around Svalbard and a comparison to model results will be shown. This dataset can later serve as a reference for the question, how representative the measurements in Ny-Alesund on Spitzbergen are for the nearby arctic region.&lt;/p&gt;&lt;p&gt;[1] Wendisch et al., 2019: The Arctic Cloud Puzzle: Using ACLOUD/PASCAL Multi-Platform Observations to Unravel the Role of Clouds and Aerosol Particles in Arctic Amplification, Bull. Amer. Meteor. Soc., 100 (5), 841&amp;#8211;871, doi:10.1175/BAMS-D-18-0072.1&lt;br&gt;[2] Rowe et al., 2019: Toward autonomous surface-based infrared remote sensing of polar clouds: retrievals of cloud optical and microphysical properties, Atmos. Meas. Tech., 12, 5071&amp;#8211;5086, https://doi.org/10.5194/amt-12-5071-2019&lt;/p&gt;

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