Energy and nutrient fluxes from rivers and streams into terrestrial food webs

2006 ◽  
Vol 57 (1) ◽  
pp. 15 ◽  
Author(s):  
Andrea Ballinger ◽  
P. S. Lake
Keyword(s):  
Food Webs ◽  
River Regulation ◽  
Ecological Impacts ◽  
Allochthonous Inputs ◽  
Productivity Gradients ◽  
Research Questions ◽  
Ecological Importance ◽  
Landscape Scales ◽  
Riverine Systems ◽  
Exchange Surface

Ecologists long have been aware that there is flux of energy and nutrients from riverine systems to the surrounding terrestrial landscape and vice versa. Riparian ecotones are diverse and ecologically important. Consequently, there is substantial literature examining faunal-mediated transfers of energy and nutrients from rivers into terrestrial food webs. A wide variety of taxa has been shown to utilise riparian resources, from species specialised for existence at the aquatic–terrestrial interface to opportunistic predators and scavengers. Outputs from rivers may be influenced by productivity gradients, channel geometry and the condition of the exchange surface. Until recently, consideration of faunal-transferred, allochthonous inputs has been peripheral to other research questions. The development of general models of inter-habitat transfers, together with advances in technology, has placed questions about the ecological importance of riverine outputs squarely on the research agenda. Researchers now are investigating how aquatic subsidies influence food-web dynamics at landscape scales. However, ecologists continue to largely ignore subsidisation of terrestrial food webs by energy and nutrients from floodwaters in lowland river–floodplain systems. The dearth of information about the benefits of flooding to terrestrial consumers appears to have resulted in underestimation of the gross ecological impacts of river regulation.

scholarly journals A simple mooring modification reduces impacts on seagrass meadows

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Anna L. Luff ◽  
Emma V. Sheehan ◽  
Mark Parry ◽  
Nicholas D. Higgs
Keyword(s):  
Species Richness ◽  
Seagrass Meadow ◽  
Habitat Degradation ◽  
Ecological Impacts ◽  
Sediment Composition ◽  
Simple Modification ◽  
Seagrass Meadows ◽  
Ecological Importance ◽  
Detrimental Impact ◽  
Seagrass Density

AbstractMoorings can have a detrimental impact on seagrass, fragmenting the meadows, resulting in the habitat degradation. To reduce contact of the moorings with the seabed we attached small floats along the chain of a traditional swing mooring and monitored the ecological impacts of this modified mooring, with reference to a standard swing mooring, in a seagrass meadow under high tidal influence. After three years, seagrass density surrounding the modified mooring was over twice as high as that of the standard mooring, with blade length surrounding the modified mooring also found to exceed that of the standard mooring. Seagrass-associated epifaunal species richness was twice as high surrounding the modified mooring compared to the standard mooring. Sediment composition was considerably finer at the modified mooring, indicative of increased disturbance surrounding the standard mooring. A simple modification to existing swing moorings can mitigate some of the impacts of moorings on seagrass meadows, whilst accommodating for tidal fluctuations. The scale of the differences observed between the mooring types demonstrates the susceptibility of seagrass meadows to damage from swing moorings. Given the ecological importance of these habitats, it is crucial that action is taken to reduce further degradation, such as that demonstrated here.

Differences in Bifenthrin and Fipronil Susceptibility Among Invasive Latrodectus spp. (Araneae: Theridiidae) and Nontarget Spiders in Japan

2021 ◽  
Author(s):  
Daisuke Hayasaka ◽  
Tomoki Numa ◽  
Takuo Sawahata
Keyword(s):  
Ecological Impacts ◽  
Toxicity Tests ◽  
Effective Population ◽  
Pyrethroid Insecticides ◽  
Parasteatoda Tepidariorum ◽  
Residual Toxicity ◽  
Insecticide Concentration ◽  
Nontarget Species ◽  
Spider Communities ◽  
Ecological Importance

Abstract Prompt responses to invasive Latrodectus spiders introduced unintentionally are needed worldwide due to their medical and ecological importance. Latrodectus species are chemically controlled using pyrethroid insecticides despite concerns about the ecological impacts of these compounds on biodiversity/ecosystems. Here, the relative sensitivities (acute toxicity: 48-h LC50) of Latrodectus hasseltii Thorell and Latrodectus geometricus C.L. Koch from Japan to the conventional neurotoxic insecticide bifenthrin (pyrethroid) and a new candidate insecticide, fipronil (phenylpyrazole), were examined. Acute residual toxicity tests of these compounds in two nontarget spiders (Parasteatoda tepidariorum C.L. Koch (Araneae: Theridiidae), Badumna insignis L. Koch (Araneae: Desidae)) were conducted for comparison. To test whether bifenthrin and fipronil toxicities differed among the four spiders, corresponding species sensitivity distributions (SSDs) were compared, and hazardous concentrations were determined. Sensitivity (especially in the nontarget species) was two to four orders of magnitude higher for bifenthrin than for fipronil. The SSD patterns of the two insecticides differed significantly, with the spider communities being more sensitive to bifenthrin than to fipronil. The lethal bifenthrin concentration for Latrodectus may reduce spider populations by over 70–90%. If L. hasseltii (established throughout Japan) is targeted for effective population suppression rather than L. geometricus (with a limited distribution range) using the specified insecticide concentration (LC50 value) for fipronil, less than 20% of spider communities will be impacted. Chemical operations aimed at the effective population management and subsequent eradication of invasive Latrodectus spiders while supporting local biodiversity conservation would benefit from considerations of fipronil dosages and target species sensitivities.

scholarly journals Stable isotope patterns in lake food webs reflect productivity gradients

Ecosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
Author(s):  
Kyle D. Zimmer ◽  
Ryan C. Grow ◽  
Angela R. Tipp ◽  
Brian R. Herwig ◽  
David F. Staples ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Food Webs ◽  
Productivity Gradients

scholarly journals The effects of altered flow and bed sediment on macroinvertebrates in stream mesocosms

2017 ◽  
Vol 68 (3) ◽  
pp. 496 ◽  
Author(s):  
Ivor Growns ◽  
John F. Murphy ◽  
J. Iwan Jones
Keyword(s):  
Turbulent Flow ◽  
Fine Particles ◽  
Anthropogenic Disturbances ◽  
River Regulation ◽  
Laminar Flows ◽  
Ecological Impacts ◽  
Transitional Flow ◽  
Flow Rates ◽  
Altered Hydrology ◽  
Stream Mesocosms

River regulation and altered land use are common anthropogenic disturbances resulting in ecological impacts through siltation or altered hydrology. We tested the separate and combined effects of increased flow and fine particles (colmation) on macroinvertebrates in flume mesocosms. We hypothesised that increased flow would reduce any effects of colmation. We tested two bed types, namely clean and colmated sediment where fines were 10% by weight. Two flow rates were initially established, namely a turbulent flow in six mesocosms and a lower rate to create a transitional flow between turbulent and laminar flows in the remaining six mesocosms. After 30 days, macroinvertebrates were sampled and the flow in three turbulent-flow mesocosms and three transitional-flow mesocosms switched to the lower and higher flow rates respectively, thus creating four flow scenarios. The experiment was concluded after sampling macroinvertebrates again at Day 70. We demonstrated that colmation and decreased flows individually result in decreased density and richness of macroinvertebrates and altered assemblage and trait structure. However, our hypothesis that higher flows would ameliorate any effects of fines was not supported. Further research is required to evaluate whether lower thresholds of colmation have ecological impacts and determine the velocities required to ameliorate those impacts.

scholarly journals PATRONES DEL PAISAJE Y ESCENARIOS DE RESTAURACIÓN EN COLOMBIA: ACERCANDO ESCALAS

2016 ◽  
Vol 21 (1Supl) ◽  
pp. 229-239 ◽  
Author(s):  
Dolors Armenteras ◽  
Orlando Vargas
Keyword(s):  
Land Use ◽  
Ecological Impacts ◽  
Negative Effects ◽  
Ecological Functions ◽  
Complex Interactions ◽  
Landscape Processes ◽  
Toma De Decisiones ◽  
Landscape Scales ◽  
Natural Dynamics ◽  
Land Use And Management

<p>El paisaje, entendido como un mosaico heterogéneo, es una unidad donde interactúan ecosistemas, especies y el hombre con el uso que este último hace del mismo. El paisaje es el resultado de complejas interacciones, no solo producto de dinámicas naturales sino del balance de la oferta y la demanda de la sociedad ante la preferencia por los recursos que este ofrece. Este equilibrio causa impactos ecológicos sobre los ecosistemas y la diversidad de organismos que ocupan los paisajes. El uso y manejo del territorio aumenta la heterogeneidad espacial, en muchos casos a través de la pérdida y  fragmentación de hábitat. Estos procesos traen alteraciones sobre el funcionamiento de los ecosistemas, afectando funciones y procesos ecológicos que dependen del flujo de energía y materiales a través de paisajes. El objetivo de este trabajo es avanzar en la comprensión de los orígenes de la heterogeneidad resultante de estas dinámicas, para mitigar sus efectos y entender cómo planificar y manejar los paisajes. Restaurar,  rehabilitar y recuperar ecosistemas son estrategias para asegurar la conservación, sostenibilidad y en algunos casos la recuperación de servicios ecosistémicos. En ocasiones las escalas de paisaje y aquellas a las cuales se realizan actividades de restauración se encuentran alejadas en la práctica. Este artículo presenta una revisión de conceptos claves en ecología del paisaje y de restauración, acercando escalas intrínsecas de los fenómenos y de toma de decisiones para el desarrollo de escenarios de manejo y restauración en Colombia. </p><p> </p><p>Abstract</p><p>The landscape, understood as a heterogeneous mosaic is a unit where ecosystems, species and man’s land use interact. It is the result of complex interactions, not only as a result of natural dynamics but also the balance created between the supply and the demand of society driven by the preference for certain resources. This balance causes ecological impacts both on ecosystems and the diversity of organisms that occupy the landscape. Land use and management tend to increase the spatial heterogeneity in many<br />cases through landscape processes such as the habitat loss and fragmentation. These processes bring alterations in the functioning<br />of ecosystems, affecting the ecological functions and those processes that depend on the flow of energy and materials through landscapes. The objective of this paper is to advance in the understanding of the origins of such heterogeneity in order to mitigate its negative effects and to better plan and manage landscapes. All restore, rehabilitate and ecosystems recovery, are strategies toensure the conservation, sustainability, and in some cases recovery of ecosystem services. Often landscape scales and those to whichrestoration activities are carried away are very distant in practice. This article presents a reflection carried out within the frameworkof the Chair Mutis 2015, it presents an overview of the key concepts in landscape ecology and restoration and an attempt to bridgeintrinsic and decision making scales to advance in the development of restoration scenarios in Colombia starting from the landscape scale but integrating local knowledge and actions.</p>

Social and Ecological Impacts of Conquest and Colonization in New Spain

2021 ◽  
Author(s):  
Vera S. Candiani
Keyword(s):  
New Spain ◽  
Arid Regions ◽  
Environmental Changes ◽  
The United States ◽  
Ecological Impacts ◽  
Urban Landscapes ◽  
The Social ◽  
Research Questions ◽  
The Arid Regions ◽  
The Individual

Throughout continental New Spain—both the Mesoamerican heartland and the arid regions later conquered by the United States—colonization brought environmental changes through the social and political regimes that it deployed. Indigenous demographic decline, exotic organisms, mining, and relations of property and production in agriculture and pastoralism affected socioecosystems and transformed landscapes over time. Beyond the individual and aggregate impacts of biological invasions or the fact of newcomers’ presence, key research questions are how, through whom, and with what technological packages and logics the changes penetrated and became imbricated in preexisting socioecologies following the conquest.Hispanic appropriation of Amerindian landesque capital between the sixteenth and eighteenth centuries might be compared to that of Christian colonists of Iberia as they took Muslim productive and urban landscapes between the twelfth and sixteenth: it allowed Spanish settlers to seize the opportunity when it came to extracting and generating wealth from newfound lands. This wealth was sustained by a pluriethnic peasantry whose persistence paradoxically also hindered the complete capitalist transformation of relations of property, production, and exchange of nature. The landscapes that resulted were not just variously Hispanized but also variously wrested from local, subsistence, communal control, indigenous or otherwise.

scholarly journals First study of food webs in a large glacial river: the trophic role of invasive trout

2020 ◽  
Vol 18 (3) ◽  
Author(s):  
Marina Tagliaferro ◽  
Sean P. Kelly ◽  
Miguel Pascual
Keyword(s):  
Rainbow Trout ◽  
Food Webs ◽  
Fish Species ◽  
Lake Trout ◽  
Trophic Position ◽  
Life Stage ◽  
Trophic Levels ◽  
Basal Resources ◽  
Ecological Importance ◽  
Δ15n And Δ13c

Abstract The aim of this study was to determine the food webs structure of a large Patagonian river in two river sections (Upstream and Midstream) and to evaluate isotopic overlap between native and introduced species. We used stable isotope analyses of δ15N and δ13C and stomach content. The Upstream section had a more complex food webs structure with a greater richness of macroinvertebrates and fish species than Midstream. Upstream basal resources were dominated by filamentous algae. Lake Trout were found to have a higher trophic position than all other fish species in that area although, the most abundant fish species, were Rainbow Trout. Depending on the life stage, Rainbow Trout shifted from prey to competitor/predator. In the Midstream section, the base of the food webs was dominated by coarse particulate organic matter, and adult Rainbow Trout had the highest trophic level. Isotopic values changed among macroinvertebrates and fish for both areas. The two most abundant native and invasive species — Puyen and Rainbow Trout — showed an isotopic separation in Midstream but did not in Upstream areas. The presence of invasive fish that occupy top trophic levels can have a significant impact on native fish populations that have great ecological importance in the region.

scholarly journals Microplastics negatively affect soil fauna but stimulate microbial activity: insights from a field-based microplastic addition experiment

2020 ◽  
Vol 287 (1934) ◽  
pp. 20201268 ◽  
Author(s):  
Dunmei Lin ◽  
Guangrong Yang ◽  
Pengpeng Dou ◽  
Shenhua Qian ◽  
Liang Zhao ◽  
...  
Keyword(s):  
Food Webs ◽  
Structural Equation ◽  
Soil Fauna ◽  
Soil Microbial Communities ◽  
Ecological Impacts ◽  
Trophic Levels ◽  
Soil Community ◽  
Soil Microbial ◽  
Soil Food Webs ◽  
Manipulation Experiment

Microplastics are recognized as an emerging contaminant worldwide. Although microplastics have been shown to strongly affect organisms in aquatic environments, less is known about whether and how microplastics can affect different taxa within a soil community, and it is unclear whether these effects can cascade through soil food webs. By conducting a microplastic manipulation experiment, i.e. adding low-density polyethylene fragments in the field, we found that microplastic addition significantly affected the composition and abundance of microarthropod and nematode communities. Contrary to soil fauna, we found only small effects of microplastics on the biomass and structure of soil microbial communities. Nevertheless, structural equation modelling revealed that the effects of microplastics strongly cascade through the soil food webs, leading to the modification of microbial functioning with further potential consequences on soil carbon and nutrient cycling. Our results highlight that taking into account the effects of microplastics at different trophic levels is important to elucidate the mechanisms underlying the ecological impacts of microplastic pollution on soil functioning.

scholarly journals Responses of phytoplankton benthic propagules to macronutrient enrichment and varying light intensities: elucidation from monsoonal estuaries

2021 ◽  
Author(s):  
Jagadish S Patil ◽  
K Sathish
Keyword(s):  
River Discharge ◽  
Photosynthetic Activity ◽  
Maximum Growth ◽  
Single Species ◽  
Coastal Sediments ◽  
Light Intensities ◽  
Phosphate Silicate ◽  
Total Community ◽  
Ecological Importance ◽  
Riverine Systems

Abstract The ecological importance of phytoplankton-benthic-propagules (PBP) from coastal sediments, except tropical-monsoonal-estuaries/coast, is well documented. Monsoonal estuaries recieves a high amount of benthic suspension (sediments, other detritus, PBP, and nutrients) due to high river-discharge during monsoon, bringing drastic changes in the environment (affecting water transparency, macronutrients concentration, and salinity), which in turn influence the plankton and phytoplankton per se. This study elucidates PBP germination and subsequent growth representing downstream, midstream, and upstream locations of monsoon-influenced Mandovi-Zuari riverine systems (Goa, India), to macronutrients (nitrate, phosphate, silicate, and in-combination) and light-intensities at higher salinity. Since, PBP, after introduction to estuary, experience higher salinity conditions with reduced river-discharge salinity of ~35 PSU was selected. Diatoms dominated the viable PBP community, but the maximum growth and sustained photosynthetic activity were observed when macronutrients were supplied in combination then individual supply. Here, the utility of the variable fluorescence technique in PBP resurrection (detection of viability and responses) was also explored. The PBP lag-period was similar for macronutrients but decreased with an increase in light-intensity. For PBP (germination and photosynthetic activity), light-intensities drive the rate of improvement/development, whereas the nutrients are essential for maintaining vegetative population upon germination. The PBP dominance of common planktonic species (Skeletonema and Thalassiosira) along the river also signifies the role of seawater intrusion in distribution. Both species are light-sensitive, responded similarly, and known to cause single species blooms and contributed significantly to the total community in the region, but on different occasions depending on the species tolerance to salinity.

scholarly journals Sediment Bound Contaminants in a Remote Northern Delta

1998 ◽  
Vol 29 (4-5) ◽  
pp. 397-414 ◽  
Author(s):  
David Milburn ◽  
Terry D. Prowse
Keyword(s):  
Organic Contaminants ◽  
Low Flow ◽  
Winter Period ◽  
Special Focus ◽  
Fine Grained ◽  
Sediment Size ◽  
Natural Tendency ◽  
Environmentally Sensitive ◽  
Ecological Importance ◽  
Riverine Systems

Deltas of major rivers are among the most productive and environmentally sensitive components of riverine systems in cold regions, and are of great hydrological and ecological importance. Much of their productivity stems from the supply of nutrient-rich sediments that rejuvenate in-channel, perched and riparian habitats. Such sediments, however, can also be a source of organic contaminants and deltas, because of their natural tendency to accumulate sediments, may become retention zones or sinks of these. The objective of this research was to determine the nature of sediment-related organic contaminant deposition in the Slave River Delta, Canada – a remote area that is now experiencing the effects of rapid upstream development. A special focus was placed on the protracted low-flow period that characterizes the winter period during which there should be a significant deposition of fine-grained sediment – size fractions with an affinity to adsorb organic contaminants. Results of an exploratory field program conducted during the 1997 pre-breakup and pre-freeze-up periods support the concept that the under-ice period is a time of significant fine-grained sediment deposition. Moreover, the contaminant load was found to be higher at the end of the winter flow recession rather than in late autumn following the major summer flow events. Comparisons of the observed contaminant levels measured in the delta are also made with those recorded by others in the upstream river that feeds the Slave Delta and in Great Slave Lake downstream of the delta.

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