scholarly journals Epiphyton in Agricultural Streams: Structural Control and Comparison to Epilithon

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3443
Author(s):  
Lishani Wijewardene ◽  
Naicheng Wu ◽  
Pau Giménez-Grau ◽  
Cecilie Holmboe ◽  
Nicola Fohrer ◽  
...  
Keyword(s):  
Nutrient Availability ◽  
Structural Control ◽  
Explanatory Power ◽  
Management Strategies ◽  
Habitat Conditions ◽  
Lowland Streams ◽  
Micro Scale ◽  
Agricultural Streams ◽  
Specific Biomass ◽  
Stream Biofilms

Stream biofilms play an important role in the structure, functioning, and integrity of agricultural streams. In many lowland streams, macrophyte vegetation is abundant and functions as an important substrate for biofilm (epiphyton) in addition to the gravel and stone substrate for epilithon on the stream bed. We expect that reach-scale habitat conditions in streams (e.g., nutrient availability, hydraulic conditions) affect the epiphyton and epilithon biomass and composition, and that this effect will be substrate-specific (macrophytes and stones). The objectives of our study were (i) to describe concurrent changes in epiphyton and epilithon biomass and composition over a year in agricultural streams, and (ii) to determine the substrate specific reach-scale habitat drivers for the epiphyton and epilithon structure. We monitored epiphyton and epilithon biofilm biomass and composition at three-week intervals and reach-scale environmental conditions daily during a year for two agricultural steams. The results showed that epiphyton and epilithon communities differed in biomass, having high substrate specific biomass in epilithon compared to epiphyton. Epiphyton was mainly composed of diatom and green algae, while cyanobacteria were more important in epilithon, and the diatom species composition varied between the two biofilm types. Epiphyton structural properties were less influenced by reach-scale hydrology and nutrient availability compared to epilithon. The overall explanatory power of the measured environmental variables was low, probably due to micro-scale habitat effects and interactive processes within stream biofilms. Knowledge of biofilm control in agricultural streams is important in order to improve management strategies, and future studies should improve the understanding of micro-scale habitat conditions, interactive relationships within biofilms and between the biofilm and the substrates.

Consistent patterns of maturity and density-dependent growth among populations of walleye (Sander vitreus): application of the growing degree-day metric

2010 ◽  
Vol 67 (7) ◽  
pp. 1057-1067 ◽  
Author(s):  
Paul A. Venturelli ◽  
Nigel P. Lester ◽  
Terry R. Marshall ◽  
Brian J. Shuter
Keyword(s):  
Growth Rate ◽  
Explanatory Power ◽  
Management Strategies ◽  
Fold Increase ◽  
Fish Growth ◽  
Growing Degree Days ◽  
Sander Vitreus ◽  
Degree Days ◽  
Regional Management ◽  
Dependent Growth

Growing degree-days (GDD, °C·days) are an index of ambient thermal energy that relates directly to an ectotherm’s cumulative metabolism but is rarely used to describe growth and development in fish. We applied GDD to length and maturity data from 416 populations of walleye ( Sander vitreus ) from Ontario and Quebec, Canada (mean annual GDD = 1200 to 2300 °C·days). On average, males matured after they had experienced 6900 °C·days and reached 350 mm total length (L) (n = 77 populations), and females matured after 10 000 °C·days and at 450 mm L (n = 70). Across 143 populations, GDD accounted for up to 96% of the variation in the length of immature walleye but also revealed a twofold difference in growth rate that was indicative of variation in food availability. When applied to data from eight populations in which walleye abundances have changed dramatically over time, GDD revealed a 1.3-fold increase in immature growth rate when abundance was low compared with when it was high. Our results both demonstrate the explanatory power of GDD with respect to fish growth and maturity and inform the development of regional management strategies for walleye.

Spatial and Temporal Changes in Habitat Conditions in the Na'aman Stream Ecosystem, Israel

1993 ◽  
Vol 27 (7-8) ◽  
pp. 387-395
Author(s):  
Jean-Jacques Jennings ◽  
Avital Gasith
Keyword(s):  
Water Quality ◽  
Species Diversity ◽  
A Priori ◽  
Hydrological Regime ◽  
Late Summer ◽  
Polluted Water ◽  
Habitat Conditions ◽  
Stream Ecosystem ◽  
Lowland Streams ◽  
Coastal Streams

Nahal Na'aman is a small, shallow coastal stream in northern Israel. A three year study was conducted to examine the effect of habitat conditions on the biological structure and function of the stream ecosystem. Here we describe temporal and spatial changes in the water regime and water quality as measures of the stream's habitat conditions. Habitat condition is strongly influenced by the hydrological regime and the water quality. In dry years the water level drops and the upper section of the stream may dry up completely. Inflow of polluted water from various sources increasingly reduces water quality downstream. In general, the Na'aman may be categorized as oligo- to mesohaline stream, highly enriched with organic matter and nutrients. Sporadic pollution events markedly affect the water quality resulting in hypertrophic conditions, particularly at times of low stream levels. Low water quality was detected also in association with the drying and refilling of the stream's sections in late summer and in fall, respectively, and following runoff in winter. The oligohaine nature of the stream a priori reduces species diversity relative to other freshwater, lowland streams/Based on water quality conditions, highest species diversity may be expected in the spring area and the upper section of the stream. However, habitat conditions in this section are most unstable due to changes of the hydrological regime. This, in turn, is expected to further reduce species richness and diversity. The extreme conditions are expected to determine the limit for the development of plant and animal life in the stream. This study illustrates the inherent problems of the coastal streams of Israel, namely, diminishing natural flow which is often replaced by discharge of effluent or sewage. Rehabilitation of the Na'aman and other coastal streams demands a radical solution for these problems.

Association of reduced riparian vegetation cover in agricultural landscapes with coarse detritus dynamics in lowland streams

2008 ◽  
Vol 59 (11) ◽  
pp. 998 ◽  
Author(s):  
D. J. Reid ◽  
P. S. Lake ◽  
G. P. Quinn ◽  
P. Reich
Keyword(s):  
Canopy Cover ◽  
Agricultural Landscapes ◽  
Allochthonous Input ◽  
Lowland Streams ◽  
South Eastern ◽  
Eastern Australia ◽  
Agricultural Streams ◽  
Standing Stocks ◽  
Allochthonous Detritus ◽  
South Eastern Australia

Studies were conducted on streams flowing through agricultural floodplains in south-eastern Australia to quantify whether reductions in riparian canopy cover were associated with alterations to the input and benthic standing stocks of coarse allochthonous detritus. Comparisons were made among three farmland reaches and three reaches within reserves with intact cover of remnant overstorey trees. Detritus inputs to these reaches were measured monthly over 2 years using litter traps. Direct inputs to streams within the reserves were relatively high (550–617 g ash free dry weight (AFDW) m–2 year–1), but were lower at farmland reaches with the lowest canopy covers (83–117 gAFDW m–2 year–1). Only a minor fraction of the total allochthonous input (<10%) entered any of the study reaches laterally. The mean amounts of benthic detritus were lowest in the most open farmland reaches. Standing stocks of benthic detritus were found to be highly patchy across a large number of agricultural streams, but were consistently very low where the streamside canopy cover was below ~35%. Canopy cover should be restored along cleared agricultural streams because allochthonous detritus is a major source of food and habitat for aquatic ecosystems. Given the absence of pristine lowland streams in south-eastern Australia, those reaches with the most intact remnant overstorey canopies should be used to guide restoration.

Social media review rating versus traditional customer satisfaction

2017 ◽  
Vol 29 (2) ◽  
pp. 784-802 ◽  
Author(s):  
Woo Gon Kim ◽  
Seo Ah Park
Keyword(s):  
Social Media ◽  
Customer Satisfaction ◽  
Performance Metrics ◽  
Explanatory Power ◽  
Management Strategies ◽  
Content Type ◽  
Hotel Performance ◽  
Online Travel ◽  
Practical Implications ◽  
Media Review

Purpose This paper aims to examine the effects of traditional customer satisfaction (CS) relative magnitude and social media review ratings on hotel performance and to explore which online travel intermediaries’ review ratings serve as the most reliable and valid predictor for hotel performance. Design/methodology/approach In 2014, CS and hotel performance data were collected from the internal database of full-service hotels operated and managed by a large hotel chain in the USA. Each property’s social media review ratings data were hand-collected from major online travel intermediaries and social media websites. Findings The results of this study indicate that social media review rating is a more significant predictor than traditional CS for explaining hotel performance metrics. Additionally, the social media review rating of TripAdvisor is the best predictor for hotel performance out of the other intermediaries. Research limitations/implications This research contributes to the hospitality literature because it examines the incremental explanatory power of social media review rating and traditional CS on hotel performance. Among the leading online travel intermediaries, the findings show that TripAdvisor’s social media review rating has the most salient effect on hotel performance. Practical implications The result of this study provides useful practical implications for hotel marketers and revenue managers. This study assists hotel marketers and revenue managers in better allocating their budget for marketing and suggests ways for channel optimization. Originality/value The finding of this study will help revenue managers, marketing managers, and hotel owners make decisions regarding their marketing budget allocation to their social media marketing campaign and select the optimal online travel intermediaries as part of their channel management strategies.

scholarly journals Potential of submerged macrophytes to support food webs in lowland agricultural streams

2017 ◽  
Vol 68 (3) ◽  
pp. 549 ◽  
Author(s):  
Robyn L. Paice ◽  
Jane M. Chambers ◽  
Belinda J. Robson
Keyword(s):  
Food Webs ◽  
Riparian Vegetation ◽  
Nitrogen Isotopes ◽  
Submerged Macrophytes ◽  
Good Condition ◽  
Agricultural Landscapes ◽  
Feeding Strategies ◽  
Lowland Streams ◽  
Agricultural Streams ◽  
Basal Resources

Submerged plants are often abundant in lowland streams in agricultural landscapes, but little is known of their role in stream ecosystems compared to riparian vegetation. We investigated the importance of submerged macrophytes as a basal resource of food webs in stream reaches with good and poor riparian vegetation condition, using mixing model analysis with stable carbon and nitrogen isotopes. Epilithic periphyton and terrestrial detritus were important basal resources in good condition reaches, although where macrophytes were present they contributed to food webs. Higher assimilation of either the macrophyte Cycnogeton huegelii or conspicuous epiphytes on C. huegelii leaves was associated with poor riparian condition. Where Potamogeton ochreatus and Ottelia ovalifolia occurred in poor condition reaches, these macrophytes contributed moderately to the food web, but were probably of greater importance as substrates for epiphytic algae. Mixing models indicated invertebrates commonly had generalist feeding strategies, feeding on the most available resource at each reach. Thus, where riparian vegetation is limited, submerged macrophytes may support opportunistic consumers both directly and as a substrate for epiphytes, thereby partially compensating for the loss of allochthonous resources in lowland agricultural streams.

scholarly journals Epipelic biofilms respond early to the impacts of urbanization in lowland streams

2020 ◽  
Author(s):  
Joaquín Cochero ◽  
María Mercedes Nicolosi Gelis
Keyword(s):  
Water Quality ◽  
Urban Areas ◽  
Structural Changes ◽  
Water Quality Monitoring ◽  
Active Biomonitoring ◽  
Lowland Streams ◽  
Translocation Experiments ◽  
Stream Biofilms ◽  
Biofilm Development ◽  
Urbanized Streams

ABSTRACTMultiple structural and functional endpoints of stream biofilms are employed by water quality monitoring programs to detect both direct and indirect environmental impacts. Since multiple co-occurring stressors influence biofilm development, active biomonitoring (translocation experiments) could provide a useful monitoring tool that reflects the overall water quality of the urbanized sites. The aim of this research was to study the short-term responses of epipelic biofilms caused by their translocation to more polluted reaches in lowland urban streams. Fluvial sediment was translocated in three streams that run through urban areas following an urbanization gradient. The epipelic biofilms in the sediment were sampled to identify any fast occurring changes in their algal and bacterial biomasses, in their respiration and oxygen consumption. The results show that structural changes in the biofilm, such as an increased bacterial density and chlorophyll-a concentration, were measurable after two days of exposure to sites with impaired water quality. These immediate changes in the structure of the biofilm indicate that they are sensitive endpoints that can be employed in fast and inexpensive biomonitoring programs in urbanized streams.

Speckled trout population parameters, habitat conditions and management strategies in lakes in Nova Scotia, Canada

2016 ◽  
Vol 48 (2) ◽  
pp. 189
Author(s):  
Amy Ryan ◽  
John L. MacMillan
Keyword(s):  
Nova Scotia ◽  
Population Density ◽  
Yellow Perch ◽  
Management Strategies ◽  
Fork Length ◽  
Small Population ◽  
Population Parameters ◽  
Habitat Conditions ◽  
Trout Population ◽  
Density And Biomass

A principal components analysis was conducted on the results of published reports and data sets from technical papers that include speckled trout Salvelinus fontinalis population estimates from 14 Nova Scotia lakes. The purpose of this paper was to identify the factors that influenced trout density and biomass. Population parameters, including mean fork length (cm), population density (n/ha), and population biomass (kg/ha), relative to variation in lake size, acidity, and competitor species were assessed and compared among lakes. Populations with small mean length and slow growth displayed larger fish density and biomass suggesting density-dependence. Acidic conditions potentially impact spawning potential and reduced recruitment that resulted in small population density and larger trout. The number of other fish species present in the lakes was used as an index of competition and had the greatest impact on trout density and biomass in Nova Scotia lakes. Yellow perch seemed to have the most impact of all the competitor species. In five lakes that contained yellow perch the mean trout population biomass was 0.19 kg-ha-1 (0.2,SD) compared to 4.5 kg-ha-1 (0.26, SD) in eight lakes that did not contain perch species. Lentic habitat conditions can greatly influence the potential success of different fisheries management strategies.

scholarly journals Weed regulation by crop and grassland competition: critical biomass level and persistence rate

2019 ◽  
Author(s):  
Mauricio Z. Schuster ◽  
François Gastal ◽  
Diana Doisy ◽  
Xavier Charrier ◽  
Anibal de Moraes ◽  
...  
Keyword(s):  
Weed Management ◽  
Explanatory Power ◽  
Management Strategies ◽  
Cost Effective ◽  
List Type ◽  
Weed Biocontrol ◽  
Agronomic Practices ◽  
Precise Knowledge ◽  
Persistence Rate ◽  
Quantitative Indicators

AbstractIt is widely agreed that competition regulates plant populations and shapes communities. Many studies have suggested that crop and grassland competition can be used for cost-effective sustainable weed control. However, effective weed management requires a precise knowledge of the effects of agronomic practices and there is a lack of quantitative indicators to compare and predict the success of weed biocontrol by competition.We studied weed abundance dynamics over a 12-year period in crop-grassland rotations (rotation treatments consisted of maize, wheat and barley crops, alternating with temporary grassland maintained for three or six years in the rotation and fertilised with two different levels of nitrogen). In addition to classical statistical analysis of the different aforementioned rotation treatments, we also modelled weed abundance as a function of the crop and grassland competition, expressed here by biomasses harvested in the preceding years.We show that weed abundance decreases over the years in grassland and subsequent crops only if the grassland receives sufficient nitrogen fertiliser. Our model had a much greater explanatory power than the rotation treatments. This model estimates a critical biomass level above which weeds are suppressed in subsequent years, and below which they tend to thrive. This critical biomass level was 24.3 and 4.7 tonnes ha−1 of dry matter for crops and grassland, respectively, highlighting the greater competitiveness of grasslands than of crops. Several clear differences between weed functional groups emerged.Synthesis and applications - This new modelling approach directly links the interannual dynamics of weed populations to current and previous biomass production levels. This approach facilitates the development of environment-friendly weed management strategies and paves the way for comparisons of the competitiveness against weeds of crops and grassland under various pedoclimatic conditions and agronomic practices.

Sign in / Sign up

Export Citation Format

Share Document