scholarly journals Influence of piers on functional groups of benthic primary producers and consumers in the channel of a subtropical coastal lagoon

2012 ◽  
Vol 60 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Paulo Roberto Pagliosa ◽  
Mauricio Cantor ◽  
Fernando Scherner ◽  
Mariana Beatriz Paz Otegui ◽  
Aurea Luiza Lemes-Silva ◽  
...  
Keyword(s):  
Functional Groups ◽  
Photosynthetic Activity ◽  
Biomass Productivity ◽  
Life Forms ◽  
Artificial Habitats ◽  
Negative Effect ◽  
Primary Producer ◽  
Filamentous Macroalgae ◽  
Benthic Ecosystems ◽  
New Habitats

Artificial habitats have become common in coastal areas worldwide and may influence the structure and functioning of benthic ecosystems. We analyze the influence of piers on the benthic morphofunctional groups of rocky seaweeds and of soft bottom macrofauna in the channel of Conceição Lagoon (southern Brazil). The main impact is a reduction in the luminosity available for photosynthetic activity which is directly related to a decrease in the biomasses of sediment microphytobenthos and of more highly structured macroalgae life-forms. Contrary to expectations, the morphotypes of potentially high biomass productivity, such as articulated coralline, corticated and leathery macroalgae, were in general less abundant and the low biomass foliose and filamentous macroalgae occurred in reference areas but not under the piers. The piers' effects on motile epifauna and infauna functional groups were site-specific and probably related to the general reduction in primary producer organisms in the new habitats. The discretely motile infauna was the only functional group able to thrive under the piers due to their reduced motility and fragile morphological structures, being benefited by the shelter provided by the artificial habitats. Our results showed that the piers might have a negative effect on the base-trophic level organisms responsible for bottom-up controls.

Bottom-up and top-down effects on phytoplankton functional groups in Hulun Lake, China

2021 ◽  
Vol 57 ◽  
pp. 3
Author(s):  
Chengxue Ma ◽  
Chang Zhao ◽  
Patteson Chula Mwagona ◽  
Ziyu Li ◽  
Zixuan Liu ◽  
...  
Keyword(s):  
Functional Groups ◽  
Phytoplankton Biomass ◽  
Eutrophic Lake ◽  
Positive Influence ◽  
Freshwater Ecosystems ◽  
Top Down ◽  
Bottom Up ◽  
Physical Chemical ◽  
Phytoplankton Functional Groups ◽  
Negative Effect

The debates about the extent to which phytoplankton in freshwater ecosystems are regulated by top-down or bottom-up forces have been ongoing for decades. This study examines the effects of bottom-up and top-down factors on the phytoplankton functional groups in a eutrophic lake. Phytoplankton and zooplankton were sampled and physical-chemical variables measured from May 2019 to October 2019 in Lake Hulun, China. Approximately 43 phytoplankton species were observed and grouped into 23 functional groups. For the zooplankton, about 27 species were observed and classified into 8 functional groups. The study revealed that the bottom-up effects of physical-chemical variables on some phytoplankton functional groups was stronger than the top-down effects of zooplankton. Water temperature (WT), total phosphorus (TP), total nitrogen (TN), conductivity (Cond), water transparency (SD), and dissolved oxygen (DO) significant influence the biomass of the phytoplankton functional groups. The biomass of phytoplankton functional groups was influenced positively by nutrient availability likely because nutrients influence the growth and reproduction of phytoplankton in freshwater. WT and DO had a positive influence on biomass of phytoplankton functional groups. Conversely, phytoplankton biomass revealed a decreasing trend when SD and Cond significantly increased. This study showed that zooplankton functional groups were positively correlated with phytoplankton biomass implying that the top-down control of phytoplankton by the zooplankton in the lake is not strong enough to produce a negative effect. It is evident that the zooplankton functional groups in Lake Hulun are controlled more by bottom-up force than top-down.

scholarly journals Landscape-wide changes in land use and land cover correlate with, but rarely explain local biodiversity change

2020 ◽  
Vol 35 (10) ◽  
pp. 2255-2273
Author(s):  
Martin Jung ◽  
Jörn P. W. Scharlemann ◽  
Pedram Rowhani
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Functional Groups ◽  
Relative Abundance ◽  
Photosynthetic Activity ◽  
Landsat Imagery ◽  
Geometric Mean ◽  
Bird Diversity ◽  
Assemblage Composition ◽  
Biodiversity Change

Abstract Context There is an ongoing debate whether local biodiversity is declining and what might drive this change. Changes in land use and land cover (LULC) are suspected to impact local biodiversity. However, there is little evidence for LULC changes beyond the local scale to affect biodiversity across multiple functional groups of species, thus limiting our understanding of the causes of biodiversity change. Objectives Here we investigate whether landscape-wide changes in LULC, defined as either trends in or abrupt changes in magnitude of photosynthetic activity, are driving bird diversity change. Methods Linking 34 year (1984–2017) time series at 2745 breeding bird survey (BBS) routes across the conterminous United States of America with remotely-sensed Landsat imagery, we assessed for each year what proportion of the landscape surrounding each BBS route changed in photosynthetic activity and tested whether such concomitant or preceding landscape-wide changes explained changes in bird diversity, quantified as relative abundance (geometric mean) and assemblage composition (Bray–Curtis index). Results We found that changes in relative abundance was negatively, and assemblage composition positively, correlated with changes in photosynthetic activity within the wider landscape. Furthermore, landscape-wide changes in LULC in preceding years explained on average more variation in bird diversity change than concomitant change. Overall, landscape-wide changes in LULC failed to explain most of the variation in bird diversity change for most BBS routes regardless whether differentiated by functional groups or ecoregions. Conclusions Our analyses highlight the influence of preceding and concomitant landscape-wide changes in LULC on biodiversity.

The Role of Abscisic Acid in the Response of Two Different Wheat Varieties to Water Deficit

2009 ◽  
Vol 64 (1-2) ◽  
pp. 77-84 ◽  
Author(s):  
Hala Ezzat Mohamed ◽  
Ghada Saber M. Ismail
Keyword(s):  
Abscisic Acid ◽  
Drought Stress ◽  
Transpiration Rate ◽  
Electrolyte Leakage ◽  
Photosynthetic Activity ◽  
Recovery Period ◽  
Wheat Varieties ◽  
Relative Water ◽  
Negative Effect

The changes in plant growth, transpiration rate, photosynthetic activity, plant pigments, electrolyte leakage, H2O2 content, lipid peroxidation, catalase activity and endogenous content of abscisic acid (ABA) were followed in the leaves of two wheat varieties (sakha 93 and 94) during drought stress and subsequent rehydration. Drought stress caused several inhibitory changes in the growth of both wheat varieties, particularly in sakha 94. Exogenous ABA treatment improved the growth of sakha 93 plants as indicated by a higher relative water content, transpiration rate and lower electrolyte leakage and also enhanced the growth during the recovery period. Such improvement may be the result of the induction of enzymatic (catalase) and non-enzymatic (carotenoid) systems. ABA treatment did not ameliorate the negative effect of drought on the growth of sakha 94.

scholarly journals Mid-term changes in the physiognomy of plant communities and functional plant groups define successional pathways of mountain vegetation in the province of Córdoba (Argentina)

2021 ◽  
Vol 48 (1) ◽  
pp. 9-24
Author(s):  
Marcos Sebastián Karlin ◽  
Sebastián Abel Arnulphi ◽  
Javier Rodolfo Bernasconi Salazar
Keyword(s):  
Functional Groups ◽  
Plant Communities ◽  
Life Forms ◽  
Plant Functional Groups ◽  
Plant Interactions ◽  
Two Phase ◽  
Plant Groups ◽  
Restoration Strategies ◽  
Mountain Vegetation ◽  
Successional Pathways

Abstract To identify restoration strategies over degraded semi-natural plant communities, successional pathways and their local controls should be identified. The objective of this work is to quantify the changes in the physiognomy and functional groups of plant communities in the Sierras Chicas of Córdoba along seven years. Lyapunov coefficients were calculated and arranged in two-phase diagrams, identifying different successional pathways over two soil categories and six plant communities. Du Rietz`s life forms were identified defining several plant functional groups. Results showed two successional pathways in the field of azonal soils and three in the field of intrazonal soils. Rainfall, extent of human-caused disturbances, and plant interactions are the leading causes explaining the changes in the structure of the plant communities. Fire and overgrazing retract the successions by altering the cover of plant communities and their functional groups.

scholarly journals Meta-ecosystem dynamics drive the spatial distribution of functional groups in river networks

2021 ◽  
Author(s):  
Claire Jacquet ◽  
Luca Carraro ◽  
Florian Altermatt
Keyword(s):  
Functional Groups ◽  
Ecosystem Model ◽  
Ecosystem Dynamics ◽  
River Networks ◽  
Ecological Communities ◽  
Landscape Matrix ◽  
Central Process ◽  
Stream Communities ◽  
Negative Effect ◽  
Ecosystem Theory

Spatial flow of material and resources is a central process structuring ecological communities. The meta-ecosystem concept provides a theoretical framework to study the interplay between local and regional flows of resources and their implications for ecosystem dynamics and functioning. Yet, meta-ecosystem theory has been applied to highly simplified systems, and the effects of meta-ecosystem dynamics in real-world landscapes, characterized by specific spatial structures, remain largely unexplored. Here, we develop a spatially explicit meta-ecosystem model for dendritic river networks based on a highly realistic landscape matrix. By formalizing a seminal concept in freshwater ecology, we show that the spatial distributions and regional biomass of major functional groups observed in stream communities are determined by specific rates of resource flows. Overall, high rates of resource flow have a negative effect on the regional biomass of all the functional groups studied and can lead to extinctions at the meta-ecosystem scale.

scholarly journals Thin terrestrial sediment deposits on intertidal sandflats: effects on pore water solutes and juvenile bivalve burial behaviour

2013 ◽  
Vol 10 (9) ◽  
pp. 14835-14860 ◽  
Author(s):  
A. Hohaia ◽  
K. Vopel ◽  
C. A. Pilditch
Keyword(s):  
Organic Matter ◽  
Pore Water ◽  
Coastal Waters ◽  
Intertidal Sediment ◽  
Sediment Deposits ◽  
Negative Effect ◽  
Water Analyses ◽  
Burial Rates ◽  
Benthic Ecosystems

Abstract. Changes in land use and climate increase the supply of terrestrial sediment (hereafter, TS) to coastal waters worldwide but the effects of these sediments on benthic ecosystem functioning are not well known. Past experiments with defaunated, intertidal sediment suggested a link between the de-oxygenation of sediments underlying a thin (mm) layer of TS and reduced burial rates of juvenile macrofaunal recruits. We examined this link predicting that surficial TS deposits will still negatively affect burial when applied to sediments that are initially well oxygenated due to bioturbation (C) or depleted of organic matter (D). We observed the behaviour of post-settlement juveniles of the tellinid bivalve Macomona liliana on the surface of four treatments; C, D, and the same sediments to which we added a thin layer of TS (CTS, DTS). Pore water analyses confirmed that the diffusive impedance of the 1.7–1.9 mm TS deposit decreased the oxygenation of the underlying intertidal sediment (CTS) but not that of the depleted sediment (DTS). Unexpectedly, (1) the application of a TS deposit significantly increased but not decreased the probability of burial, irrespectively of treatment, and (2) juveniles more likely buried into C than into D. We attribute the failure to document a negative effect of TS on the recruits' burial to the activity of the resident macroinfauna (CTS) or the absence of organic matter (DTS). Our results underline the important role of the resident macrofauna in mediating the stress response of benthic ecosystems.

scholarly journals Species convergence into life-forms in a hyperseasonal cerrado in central Brazil

2008 ◽  
Vol 68 (2) ◽  
pp. 329-339 ◽  
Author(s):  
IA. Silva ◽  
MA. Batalha
Keyword(s):  
Seasonal Variation ◽  
Species Diversity ◽  
Functional Groups ◽  
Life Form ◽  
Experimental Tests ◽  
Water Shortage ◽  
Life Forms ◽  
Ecological Communities ◽  
Central Brazil ◽  
Community Convergence

Whether the functional structure of ecological communities is deterministic or historically contingent is still quite controversial. However, recent experimental tests did not find effects of species composition variation on trait convergence and therefore the environmental constraints should play the major role on community convergence into functional groups. Seasonal cerrados are characterized by a sharp seasonality, in which the water shortage defines the community functioning. Hyperseasonal cerrados experience additionally waterlogging in the rainy season. Here, we asked whether waterlogging modifies species convergences into life-forms in a hyperseasonal cerrado. We studied a hyperseasonal cerrado, comparing it with a nearby seasonal cerrado, never waterlogged, in Emas National Park, central Brazil. In each area, we sampled all vascular plants by placing 40 plots of 1 m² plots in four surveys. We analyzed the species convergences into life-forms in both cerrados using the Raunkiaer's life-form spectrum and the index of divergence from species to life-form diversity (IDD). The overall life-form spectra and IDDs were not different, indicating that waterlogging did not affect the composition of functional groups in the hyperseasonal cerrado. However, there was a seasonal variation in IDD values only in the hyperseasonal cerrado. As long as we did not find a seasonal variation in life-form diversity, the seasonal variation of convergence into life-forms in the hyperseasonal cerrado was a consequence of the seasonal variation of species diversity. Because of high functional redundancy of cerrado plants, waterlogging promoted a floristic replacement without major changes in functional groups. Thus, waterlogging in the hyperseasonal cerrado promoted seasonal changes in species convergence into life-forms by reducing species diversity.

scholarly journals Transient Heat Waves May Affect the Photosynthetic Capacity of Susceptible Wheat Genotypes Due to Insufficient Photosystem I Photoprotection

Plants ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 282 ◽  
Author(s):  
Erik Chovancek ◽  
Marek Zivcak ◽  
Lenka Botyanszka ◽  
Pavol Hauptvogel ◽  
Xinghong Yang ◽  
...  
Keyword(s):  
Heat Wave ◽  
Photosystem I ◽  
Photosynthetic Activity ◽  
Photosynthetic Capacity ◽  
Heat Waves ◽  
Transparent Plastic ◽  
Wheat Varieties ◽  
Acceptor Side ◽  
Negative Effect ◽  
Photosynthetic Responses

We assessed the photosynthetic responses of eight wheat varieties in conditions of a simulated heat wave in a transparent plastic tunnel for one week. We found that high temperatures (up to 38 °C at midday and above 20 °C at night) had a negative effect on the photosynthetic functions of the plants and provided differentiation of genotypes through sensitivity to heat. Measurements of gas exchange showed that the simulated heat wave led to a 40% decrease in photosynthetic activity on average in comparison to the control, with an unequal recovery of individual genotypes after a release from stress. Our results indicate that the ability to recover after heat stress was associated with an efficient regulation of linear electron transport and the prevention of over-reduction in the acceptor side of photosystem I.

scholarly journals Responses of Wheat (Triticum Aestivum L.) and Maize (Zea Mays L.) Plants to Cadmium Toxicity in Relation to Magnesium Nutrition

2014 ◽  
Vol 73 (2) ◽  
pp. 359-373 ◽  
Author(s):  
Nataša Nikolić ◽  
Slobodanka Pajević ◽  
Milan Župunski ◽  
Mirjana Topić ◽  
Danijela Arsenov
Keyword(s):  
Triticum Aestivum ◽  
Zea Mays ◽  
Considerable Increase ◽  
Photosynthetic Activity ◽  
Cadmium Toxicity ◽  
Triticum Aestivum L ◽  
Carotenoid Concentration ◽  
Physiological Processes ◽  
Leaf Chlorophyll ◽  
Negative Effect

AbstractThe influence of cadmium (Cd) on physiological processes in wheat (Triticum aestivumL.) and maize (Zea maysL.) plants exposed to either optimal mineral nutrition or the absence of magnesium (Mg) as well as the accumulation of cadmium and magnesium in plant organs were studied using the method of water culture in a greenhouse. Cd treatment reduced shoot fresh mass more strongly in Mg-supplied than in Mg-deficient plants. Negative effect of Cd on photosynthetic activity was more pronounced inT. aestivumthan inZ. maysplants. Cd treatment decreased leaf chlorophyll and carotenoid concentration in bothZ. maysandT. aestivum,irrespective of the Mg supply. Cd was preferentially accumulated in the roots of both species. Catalase activity inT. aestivumleaves and roots was unaffected by Cd and Mg supply. Cd treatment did not affect Fe accumulation in the leaves of either species, while in the roots a considerable increase occurred, irrespective of the Mg nutrition. Higher tolerance ofZ. maysandT. aestivumplants to Cd toxicity exposed to Mg deficiency could partly be ascribed to the preservation of Fe nutrition.

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