scholarly journals Large-scale spatial heterogeneity of macrozooplankton in Lake of Geneva

1999 ◽  
Vol 56 (8) ◽  
pp. 1437-1451 ◽  
Author(s):  
Bernadette Pinel-Alloul ◽  
Catherine Guay ◽  
Nadine Angeli ◽  
Pierre Legendre ◽  
Pierre Dutilleul ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Water Temperature ◽  
Chlorophyll A ◽  
Large Scale ◽  
Abiotic Factors ◽  
Distribution Patterns ◽  
Small Scale ◽  
Lake Basin ◽  
Fish Biomass ◽  
Trophic Groups

Spatial distribution of macrozooplankton was studied during spring in Lake of Geneva to evaluate the influence of abiotic (water temperature and stability, nutrients) and biotic (bacteria, chlorophyll a, fish biomass) factors on macrozooplankton distribution. Mapping and spatial analyses revealed that abiotic factors, as well as crustacean abundances, were structured along a gradient in the great lake basin. Chlorophyll a biomass, bacteria density, cyclopoid abundance, and fish biomass showed more patchy or inshore-offshore distribution patterns. Using canonical analyses, we determined the relative contribution of the spatial and environmental factors to the distribution of macrozooplankton species and of trophic groups based on herbivory and omnivory/carnivory. The distribution of macrozooplankton can be explained by small-scale variations and lake gradients in abiotic and biotic factors, with a dominant contribution of the abiotic factors. Water temperature and stability, as well as ammonium, are the main factors related to macrozooplankton distribution in Lake of Geneva during spring. Chlorophyll a biomass was also related to the distribution of cyclopoids. The canonical models explained 35-72% of the variance in the distribution of total crustaceans, species, and trophic groups. However, 28-65% of the macrozooplankton variance remained unexplained, which may be due to fine-scale variations in other environmental factors.

Species Responses to Grazing and Environmental-Factors in an Arid Halophytic Shrubland Community

1987 ◽  
Vol 35 (2) ◽  
pp. 135 ◽  
Author(s):  
RB Hacker
Keyword(s):  
Environmental Factors ◽  
Soil Salinity ◽  
Large Scale ◽  
Chemical Properties ◽  
Grazing Pressure ◽  
Aerial Photographs ◽  
Small Scale ◽  
Factors Affecting ◽  
Species Responses

Species responses to grazing and environmental factors were studied in an arid halophytic shrubland community in Western Australia. The grazing responses of major shrub species were defined by using reciprocal averaging ordination of botanical data, interpreted in conjunction with a similar ordination of soil chemical properties and measures of soil erosion derived from large-scale aerial photographs. An apparent small-scale interaction between grazing and soil salinity was also defined. Long-term grazing pressure is apparently reduced on localised areas of high salinity. Environmental factors affecting species distribution are complex and appear to include soil salinity, soil cationic balance, geomorphological variation and the influence of cryptogamic crusts on seedling establishment.

scholarly journals Longitudinal sampling of external mucosae in farmed European seabass reveals the impact of water temperature on bacterial dynamics

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Daniela Rosado ◽  
Raquel Xavier ◽  
Jo Cable ◽  
Ricardo Severino ◽  
Pedro Tarroso ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Microbial Diversity ◽  
Water Temperature ◽  
Abiotic Factors ◽  
Seasonal Effect ◽  
Microbial Composition ◽  
Surrounding Water ◽  
European Seabass ◽  
And Function ◽  
The Impact

AbstractFish microbiota are intrinsically linked to health and fitness, but they are highly variable and influenced by both biotic and abiotic factors. Water temperature particularly limits bacterial adhesion and growth, impacting microbial diversity and bacterial infections on the skin and gills. Aquaculture is heavily affected by infectious diseases, especially in warmer months, and industry practices often promote stress and microbial dysbiosis, leading to an increased abundance of potentially pathogenic bacteria. In this regard, fish mucosa health is extremely important because it provides a primary barrier against pathogens. We used 16 rRNA V4 metataxonomics to characterize the skin and gill microbiota of the European seabass, Dicentrarchus labrax, and the surrounding water over 12 months, assessing the impact of water temperature on microbial diversity and function. We show that the microbiota of external mucosae are highly dynamic with consistent longitudinal trends in taxon diversity. Several potentially pathogenic genera (Aliivibrio, Photobacterium, Pseudomonas, and Vibrio) were highly abundant, showing complex interactions with other bacterial genera, some of which with recognized probiotic activity, and were also significantly impacted by changes in temperature. The surrounding water temperature influenced fish microbial composition, structure and function over time (days and months). Additionally, dysbiosis was more frequent in warmer months and during transitions between cold/warm months. We also detected a strong seasonal effect in the fish microbiota, which is likely to result from the compound action of several unmeasured environmental factors (e.g., pH, nutrient availability) beyond temperature. Our results highlight the importance of performing longitudinal studies to assess the impact of environmental factors on fish microbiotas.

scholarly journals Testing biodiversity theory using species richness of reef-building corals across a depth gradient

2019 ◽  
Vol 15 (10) ◽  
pp. 20190493 ◽  
Author(s):  
T. Edward Roberts ◽  
Sally A. Keith ◽  
Carsten Rahbek ◽  
Tom C. L. Bridge ◽  
M. Julian Caley ◽  
...  
Keyword(s):  
Species Richness ◽  
Large Scale ◽  
Coral Species ◽  
Environmental Gradients ◽  
Abiotic Factors ◽  
Empirical Support ◽  
Null Model ◽  
Local Scale ◽  
Small Scale ◽  
Energy Availability

Natural environmental gradients encompass systematic variation in abiotic factors that can be exploited to test competing explanations of biodiversity patterns. The species–energy (SE) hypothesis attempts to explain species richness gradients as a function of energy availability. However, limited empirical support for SE is often attributed to idiosyncratic, local-scale processes distorting the underlying SE relationship. Meanwhile, studies are also often confounded by factors such as sampling biases, dispersal boundaries and unclear definitions of energy availability. Here, we used spatially structured observations of 8460 colonies of photo-symbiotic reef-building corals and a null-model to test whether energy can explain observed coral species richness over depth. Species richness was left-skewed, hump-shaped and unrelated to energy availability. While local-scale processes were evident, their influence on species richness was insufficient to reconcile observations with model predictions. Therefore, energy availability, either in isolation or in combination with local deterministic processes, was unable to explain coral species richness across depth. Our results demonstrate that local-scale processes do not necessarily explain deviations in species richness from theoretical models, and that the use of idiosyncratic small-scale factors to explain large-scale ecological patterns requires the utmost caution.

The effects of salinity, turbidity and flow on fish biomass estimated acoustically in two tidal rivers

2014 ◽  
Vol 65 (3) ◽  
pp. 267 ◽  
Author(s):  
V. F. Matveev ◽  
A. D. L. Steven
Keyword(s):  
Large Scale ◽  
River System ◽  
Fish Abundance ◽  
Practical Significance ◽  
Small Scale ◽  
Fish Biomass ◽  
Strongly Correlated ◽  
Commercial Catch ◽  
Four Seasons ◽  
Annual Means

Establishing drivers of fish abundance in estuaries is an important task of both theoretical and practical significance. Commercial catch data help explain large-scale variation in fish productivity; however, there is insufficient understanding of small-scale changes. We analysed correlations between acoustically estimated fish biomass (FB) and environmental variables, which included indices of primary productivity and physio-chemistry in a coastal river system during four seasons. Spatial series of FB were obtained for the Logan River (main estuary) and the Albert River (tributary) located in South East Queensland, Australia. Most of the year, FB was significantly higher in the Albert River. Annual means for discharge, salinity and pH were significantly lower, whereas phosphorus concentrations were higher in the Albert River. Out of 15 hydrological variables tested, FB was strongly correlated only with salinity, conductivity and turbidity. In the Albert River, where fish were larger, as indicated by greater target strengths, FB was positively correlated with river discharge. Our results suggest that salinity and turbidity can be important seasonal drivers of fish abundance in communities dominated by Mugil spp. and Nematalosa erebi and that the flow-biomass relationship may appear independent of the effects of primary production.

scholarly journals PHYTOPLANKTON STATE AND CYANOTOXINS IN THE SVYATOZERO LAKE BLOOM SPOT (ONEGA LAKE BASIN, RUSSIA)

2021 ◽  
Vol 26 (1) ◽  
pp. 50-60
Author(s):  
V. S. Smirnova ◽  
◽  
E. V. Tekanova ◽  
N. M. Kalinkina ◽  
E. N. Chernova ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Large Scale ◽  
Total Content ◽  
The State ◽  
Water Bloom ◽  
Lake Basin ◽  
The North ◽  
Cyanobacterial Species ◽  
The Republic ◽  
Recreational Use

Introduction. This paper is the first to address the state of phytoplankton in eutrophic Svyatozero Lake (61о32´ N, 33о35´ E.), used for trout farming in the Republic of Karelia, in the North-Western Region of Russia, during the period of water bloom. For northern reservoirs, water bloom is not a typical phenomenon. However, due to climate warming and the large-scale development of trout breeding in the region, it becomes more urgent to study blooming reservoirs and related consequences for northern aquatic ecosystems and humans. Methods. We processed phytoplankton samples and measured photosynthesis using conventional methods. The concentration of chlorophyll a in water was determined spectrophotometrically, and the content of cyanotoxins was estimated by liquid chromatography-mass spectrometry. Results. In September 2019, we studied the structural, quantitative and functional characteristics of phytoplankton in the bloom spot. The phytoplankton abundance was 198.712 mln cells/l, the biomass was 14.945 mg/l, and the concentration of chlorophyll a reached 215.3 μg/l, which corresponded to the β-eutrophic state of the ecosystem in the study area. It was revealed that cyanobacteria corresponded to 99.8% of the biomass and 96.7% of the abundance. The species of the genus Microcystis were dominant (42%). They are well-known potential producers of cyanobacterial hepatotoxins, in particular, microcystins. We established the presence of microcystins. Their intracellular and extracellular concentrations were equal and in total amounted to 12.56 μg/l. We also identified eight structural variants of microcystins; among those, [D-Asp3] MC-RR accounted for up to 90% of the total content. The most toxic MC-LR variant was present in trace amounts only in biomass. According to the WHO standards, the content of microcystins and the number of cyanobacterial cells in the Svyatozero Lake bloom spot corresponds to average danger in the case of recreational use and can pose a threat to human health. Conclusion. It is necessary to monitor the phytoplankton composition, the presence of potentially toxic cyanobacterial species and cyanotoxins, as well as the state of trout farmed in the waters of Svyatozero Lake, since cyanotoxins can accumulate in fish tissues.

scholarly journals Unraveling the effects of environmental drivers and spatial structure on benthic species distribution patterns in Eurasian-Arctic seas (Barents, Kara and Laptev Seas)

Polar Biology ◽  
2020 ◽  
Vol 43 (11) ◽  
pp. 1693-1705
Author(s):  
Miriam L. S. Hansen ◽  
Dieter Piepenburg ◽  
Dmitrii Pantiukhin ◽  
Casper Kraan
Keyword(s):  
Environmental Factors ◽  
Spatial Structure ◽  
Large Scale ◽  
Environmental Changes ◽  
Spatial Scales ◽  
Distribution Patterns ◽  
Environmental Drivers ◽  
Arctic Seas ◽  
Faunal Distribution ◽  
The Impact

Abstract In times of accelerating climate change, species are challenged to respond to rapidly shifting environmental settings. Yet, faunal distribution and composition are still scarcely known for remote and little explored seas, where observations are limited in number and mostly refer to local scales. Here, we present the first comprehensive study on Eurasian-Arctic macrobenthos that aims to unravel the relative influence of distinct spatial scales and environmental factors in determining their large-scale distribution and composition patterns. To consider the spatial structure of benthic distribution patterns in response to environmental forcing, we applied Moran’s eigenvector mapping (MEM) on a large dataset of 341 samples from the Barents, Kara and Laptev Seas taken between 1991 and 2014, with a total of 403 macrobenthic taxa (species or genera) that were present in ≥ 10 samples. MEM analysis revealed three spatial scales describing patterns within or beyond single seas (broad: ≥ 400 km, meso: 100–400 km, and small: ≤ 100 km). Each scale is associated with a characteristic benthic fauna and environmental drivers (broad: apparent oxygen utilization and phosphate, meso: distance-to-shoreline and temperature, small: organic carbon flux and distance-to-shoreline). Our results suggest that different environmental factors determine the variation of Eurasian-Arctic benthic community composition within the spatial scales considered and highlight the importance of considering the diverse spatial structure of species communities in marine ecosystems. This multiple-scale approach facilitates an enhanced understanding of the impact of climate-driven environmental changes that is necessary for developing appropriate management strategies for the conservation and sustainable utilization of Arctic marine systems.

scholarly journals Diatoms Are Selective Segregators in Global Ocean Planktonic Communities

mSystems ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Flora Vincent ◽  
Chris Bowler
Keyword(s):  
Open Access ◽  
Large Scale ◽  
Abiotic Factors ◽  
Biotic Interactions ◽  
Distribution Patterns ◽  
Global Scale ◽  
Global Ocean ◽  
Extensive Literature ◽  
Microbial Association ◽  
Species Specific

ABSTRACT Diatoms are a major component of phytoplankton, believed to be responsible for around 20% of the annual primary production on Earth. As abundant and ubiquitous organisms, they are known to establish biotic interactions with many other members of plankton. Through analyses of cooccurrence networks derived from the Tara Oceans expedition that take into account both biotic and abiotic factors in shaping the spatial distributions of species, we show that only 13% of diatom pairwise associations are driven by environmental conditions; the vast majority are independent of abiotic factors. In contrast to most other plankton groups, on a global scale, diatoms display a much higher proportion of negative correlations with other organisms, particularly toward potential predators and parasites, suggesting that their biogeography is constrained by top-down pressure. Genus-level analyses indicate that abundant diatoms are not necessarily the most connected and that species-specific abundance distribution patterns lead to negative associations with other organisms. In order to move forward in the biological interpretation of cooccurrence networks, an open-access extensive literature survey of diatom biotic interactions was compiled, of which 18.5% were recovered in the computed network. This result reveals the extent of what likely remains to be discovered in the field of planktonic biotic interactions, even for one of the best-known organismal groups. IMPORTANCE Diatoms are key phytoplankton in the modern ocean that are involved in numerous biotic interactions, ranging from symbiosis to predation and viral infection, which have considerable effects on global biogeochemical cycles. However, despite recent large-scale studies of plankton, we are still lacking a comprehensive picture of the diversity of diatom biotic interactions in the marine microbial community. Through the ecological interpretation of both inferred microbial association networks and available knowledge on diatom interactions compiled in an open-access database, we propose an ecosystems approach for exploring diatom interactions in the ocean.

Scale-Location Dependence of the Relationship between NDVI and Environmental Factors in Wuyi Mountain

2014 ◽  
Vol 955-959 ◽  
pp. 3828-3834
Author(s):  
Wei Cheng Zou ◽  
G. R. Xiao
Keyword(s):  
Environmental Factors ◽  
Large Scale ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Windward Side ◽  
Slope Aspect ◽  
Leeward Side ◽  
Small Scale ◽  
Medium Scale ◽  
Wavelet Coherency

The correlation between Normalized Difference Vegetation Index (NDVI) and environmental factors is examined at different scales and locations in world heritage of Wuyi Mountain by wavelet coherency. These factors are elevation, slope, aspect, distance to nearest resident, distance to nearest road , and distance to nearest river along two transects based on data of DEM, residents, roads, rivers and ALOS remote sensing image in 2009.The results show that:(1) The relationships between NDVI and environmental factors change along with scale. The relationships between NDVI and environmental factors in the first transect are all weak at small scale (<480m). At medium scale (480-7680m), NDVI is significantly correlated with elevation, slope, resident , and road. At large scale (>7680m), NDVI is significantly correlated with elevation, resident and river. For the second transect, NDVI is significantly correlated with aspect at small scale; and significantly correlated with elevation, aspect, slope and river at medium scale; and significantly correlated with elevation, aspect, and slope at large scale. Thus elevation is the dominant controlling factors on the vegetation cover.(2)The relationships between NDVI and environmental factors also change when location changes. There is positive correlation between NDVI and elevation below the altitude of 600 m and the windward side of the southeast monsoon above 600m, while it is negative in the leeward side above 600m. Besides, NDVI is directly related with road, resident, slope, and river in the areas where the elevation is below 1200m, but inversely above 1200m.

scholarly journals Analysis of the Impacts of Environmental Factors on Rat Hole Density in the Northern Slope of the Tienshan Mountains with Satellite Remote Sensing Data

2021 ◽  
Vol 13 (22) ◽  
pp. 4709
Author(s):  
Haiyang Shi ◽  
Qun Pan ◽  
Geping Luo ◽  
Olaf Hellwich ◽  
Chunbo Chen ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Environmental Factors ◽  
Satellite Remote Sensing ◽  
Large Scale ◽  
Remote Sensing Data ◽  
Small Scale ◽  
Driving Mechanism ◽  
Hole Density ◽  
Northern Slope ◽  
Sensing Data

Understanding the impacts of environmental factors on spatial–temporal and large-scale rodent distribution is important for rodent damage prevention. Investigating rat hole density (RHD) is one of the most effective methods to obtain the intensity of rodent damage. However, most of the previous field surveys or UAV-based remote sensing methods can only evaluate small-scale RHD and its influencing factors. However, these studies did not consider large-scale temporal and spatial heterogeneity. Therefore, we collected small-scale and in situ measurement records of RHD on the northern slope of the Tien Shan Mountains in Xinjiang (NTXJ), China, from 1982 to 2015, and then used correlation analysis and Bayesian network (BN) to analyze the environmental impacts on large-scale RHD with satellite remote sensing data such as the GIMMS NDVI product. The results show that the built BN can better quantify causality in the environmental mechanism modeling of RHD. The NDVI and LAI data from satellite remote sensing are important to the spatial–temporal RHD distribution and the mapping in the future. In regions with an elevation higher than 600 m (UPR) and lower than 600 m (LWR) of NTXJ, there are significant differences in the driving mechanism patterns of RHD, which are dependent on the elevation variation. In LWR, vegetation conditions have a weaker impact on RHD than UPR. It is possibly due to the Artemisia eaten by the dominant species Lagurus luteus (LL) in UPR being more sensitive to precipitation and temperature if compared with the Haloxylon ammodendron eaten by the Rhombomys opimus (RO) in LWR. In LWR, grazing intensity is more strongly and positively correlated to RHD than UPR, possibly due to both winter grazing and RO dependency on vegetation distribution; moreover, in UPR, sheep do not feed Artemisia as the main food, and the total vegetation is sufficient for sheep and LL to coexist. Under the different conditions of water availability of LWR and UPR, grazing may affect the ratio of aboveground and underground biomass by photosynthate allocation, thereby affecting the distribution of RHD. In extremely dry years, the RHD of LWR and UPR may have an indirect interactive relation due to changes in grazing systems.

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