Review of Certain Environmental Factors Affecting the Production of Pink and Chum Salmon

1958 ◽  
Vol 15 (5) ◽  
pp. 1103-1126 ◽  
Author(s):  
W. P. Wickett
Keyword(s):  
Environmental Factors ◽  
Preliminary Data ◽  
Chum Salmon ◽  
Environmental Changes ◽  
Early Stage ◽  
Factors Affecting ◽  
Stream Discharge ◽  
Ocean Conditions

The relation between stock and numbers of spawners is obscured by annual environmental changes. Stream discharge at the time the spawners are migrating upstream, at the time when the eggs are in the early stage of incubation, and extreme discharge during the period eggs and alevins are in the gravel can impose an 8-fold variation in the stock resulting from a given number of spawners in one area. Ocean conditions soon after the fry enter the sea have been observed to increase or decrease survival by a factor of 3. The density of spawners that produces the greatest numbers of fry is related to the average permeability of the stream bottom. Preliminary data indicate that more spawners could be used to advantage in most areas of the coast.

scholarly journals Distribution Patterns of Odonate Assemblages in Relation to Environmental Variables in Streams of South Korea

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 152 ◽  
Author(s):  
Da-Yeong Lee ◽  
Dae-Seong Lee ◽  
Mi-Jung Bae ◽  
Soon-Jin Hwang ◽  
Seong-Yu Noh ◽  
...  
Keyword(s):  
Land Use ◽  
Ecosystem Services ◽  
Environmental Factors ◽  
South Korea ◽  
Habitat Heterogeneity ◽  
Environmental Variables ◽  
Environmental Changes ◽  
Distribution Patterns ◽  
Self Organizing Map ◽  
Factors Affecting

Odonata species are sensitive to environmental changes, particularly those caused by humans, and provide valuable ecosystem services as intermediate predators in food webs. We aimed: (i) to investigate the distribution patterns of Odonata in streams on a nationwide scale across South Korea; (ii) to evaluate the relationships between the distribution patterns of odonates and their environmental conditions; and (iii) to identify indicator species and the most significant environmental factors affecting their distributions. Samples were collected from 965 sampling sites in streams across South Korea. We also measured 34 environmental variables grouped into six categories: geography, meteorology, land use, substrate composition, hydrology, and physicochemistry. A total of 83 taxa belonging to 10 families of Odonata were recorded in the dataset. Among them, eight species displayed high abundances and incidences. Self-organizing map (SOM) classified sampling sites into seven clusters (A–G) which could be divided into two distinct groups (A–C and D–G) according to the similarities of their odonate assemblages. Clusters A–C were characterized by members of the suborder Anisoptera, whereas clusters D–G were characterized by the suborder Zygoptera. Non-metric multidimensional scaling (NMDS) identified forest (%), altitude, and cobble (%) in substrata as the most influential environmental factors determining odonate assemblage compositions. Our results emphasize the importance of habitat heterogeneity by demonstrating its effect on odonate assemblages.

scholarly journals The Effect of Host, Habitat and Fasting Time on the Gut Microbiota of Amphibian

2021 ◽  
Author(s):  
Qing Tong ◽  
Li-yong Cui ◽  
Zong-fu Hu ◽  
Xiao-peng Du ◽  
Hong-bin Wang
Keyword(s):  
Environmental Factors ◽  
Gut Microbiota ◽  
Environmental Changes ◽  
Early Stage ◽  
Information Criterion ◽  
Shannon Index ◽  
Lifestyle Changes ◽  
Fasting Time ◽  
The Impact ◽  
Late Stages

Abstract Wild animals entering captivity experience radical lifestyle changes resulting in microbiota alterations, in large part due to differences in diet. However, little is known about how external environmental factors influences the gut microbiota and the interaction of the environment-host-microbe interactions in host fasting. The gut microbiota in the early stage (amA and dyA groups) and late stage of hibernation in Rana amurensis and R. dybowskii of entering captivity (amL and dyL groups) and wild environments (amS and dyS groups) was determined, and the effects of host, environmental factors and fasting time on the gut microbiota were investigated via high-throughput Illumina sequencing. The Shannon index differed significantly between the amL and dyL groups and between the amA and amS groups. The PD index differed significantly between the dyL and dyS groups. Eight core OTUs were widely distributed between species, habitats and fasting times and were dominant in abundance. Captive and wild environments, host species, and fasting time significantly affected the composition and structure of the gut microbiota. Akaike information criterion (AIC)-based model results suggested that the environment and host were the variables that needed to be included in redundancy analysis (RDA) to explain the variance in taxa. The pairwise distances between the early and late stages of hibernation of were greater in R. amurensis and R. dybowskii entering captivity than in wild. The average of OTUs shared by early and late stages of hibernation of captive frogs was significantly lower than the average of wild frogs. These results can reveal the impact of environmental changes on the gut microbiota, thereby revealing the important interactions between environment-host-microbes, and helping to protect vertebrate hosts.

Responses of a phytoplankton community to seasonal and environmental changes in Lake Nansihu, China

2017 ◽  
Vol 68 (10) ◽  
pp. 1877 ◽  
Author(s):  
Wang Tian ◽  
Huayong Zhang ◽  
Lei Zhao ◽  
Hai Huang
Keyword(s):  
Environmental Factors ◽  
Seasonal Variations ◽  
Phytoplankton Community ◽  
Algal Bloom ◽  
Environmental Changes ◽  
Conservation Strategies ◽  
Nutrient Concentrations ◽  
Phytoplankton Species ◽  
Factors Affecting ◽  
Phytoplankton Communities

Phytoplankton is the primary producer and the basis of most aquatic food webs. Characterising the variations in phytoplankton communities and the factors affecting these variations in a fluctuating environment are central issues in ecology and essential to developing appropriate conservation strategies. In the present study, seasonal variations in the phytoplankton community and the driving environmental factors were analysed based on data from Lake Nansihu in 2013. In all, 138 phytoplankton species were identified. The phytoplankton community exhibited seasonal variations, with a mean abundance that ranged from 5.00×105 cells L–1 in winter to 4.57×106 cells L–1 in summer and a mean biomass that varied from 0.44mgL–1 in winter to 3.75mgL–1 in summer. A spring algal bloom did not appear in this warm, temperate monsoon lake, but an algal bloom did appear in summer when the temperature and nutrient concentrations were high. There were substantial seasonal variations in the dominant phytoplankton taxa, from Chlorophyta, Bacillariophyta and Euglenophyta in spring to Chlorophyta and Bacillariophyta in summer, followed by dominance of Chlorophyta in autumn and Bacillariophyta in winter. Results of canonical correspondence analysis indicated that although the environmental factors affecting the seasonal variations in different phytoplankton species varied, water temperature, total nitrogen, total phosphorus and ammonia nitrogen appeared to be the most dominant. These four variables were also the main environmental factors driving the seasonal variations in the phytoplankton community in the lake. The results of the present study will be useful in guaranteeing the water quality and ecological security of Lake Nansihu.

scholarly journals From climate zone to microhabitat—environmental factors affecting the coastal distribution of tiger beetles (Coleoptera: Cicindelidae) in the south-eastern European biodiversity hotspot

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6676 ◽  
Author(s):  
Radomir Jaskuła ◽  
Mateusz Płóciennik ◽  
Axel Schwerk
Keyword(s):  
Environmental Factors ◽  
Eastern Europe ◽  
Environmental Changes ◽  
Soil Parameters ◽  
Factors Affecting ◽  
Tiger Beetle ◽  
Tiger Beetles ◽  
South Eastern ◽  
South Eastern Europe ◽  
Habitat Specialists

BackgroundTiger beetles (Coleoptera: Cicindelidae) are predatory insects usually occurring in various sandy habitats. In south-eastern Europe, especially in lowland areas located close to the sea coast, the diversity of Cicindelidae is one of the highest in the Palaearctic realm. Although previous studies conducted in different areas of the world show that many species are habitat specialists, unfortunately little is known about environmental factors affecting the diversity and distribution of tiger beetles in this region.Material and MethodsHabitat preferences for 12 tiger beetles taxa were analysed. Over 100 samples collected in eight countries located in coastal areas of the Black and Mediterranean Seas were studied, for which climate data, macrohabitat types, and soil parameters (soil humidity, salinity, pH, and structure) were investigated.ResultsMost studied Cicindelidae were characterised by narrow or very narrow habitat specialisation and did not co-occur with other ones, including 11 taxa found as habitat specialists occurring only in one or two types of macrohabitat. The most eurythopic species wasCalomera littoralis nemoraliswhich occupied four macrohabitat types. The climatic zone, altitude, and humidity were found as the most important factors in the distribution of the studied tiger beetle species. Salt marshes and sandy sea beaches were noted as the most diverse macrohabitat types.DiscussionTiger beetle fauna of south-eastern Europe consists mainly of habitat specialists sensitive to environmental changes, which makes these beetles perfect bioindicators. Moreover, as a great number of studied Cicindelidae taxa occur in habitats which are under a significant human impact, we suggest that in the studied area the group can be successfully used as a flagship taxon for insect and nature conservation.

Nonlethal assessment of freshwater mussel physiological response to changes in environmental factors

2015 ◽  
Vol 72 (10) ◽  
pp. 1460-1468 ◽  
Author(s):  
Andrea K. Fritts ◽  
James T. Peterson ◽  
Jason M. Wisniewski ◽  
Robert B. Bringolf
Keyword(s):  
Environmental Factors ◽  
Aquatic Ecosystems ◽  
Linear Models ◽  
Environmental Changes ◽  
Hierarchical Modeling ◽  
Freshwater Mussel ◽  
Stream Discharge ◽  
Modeling Techniques ◽  
Flint River ◽  
Tissue Biomarkers

The development of effective nonlethal biomonitoring techniques is imperative for the preservation of imperiled freshwater mussel populations. Changes in hemolymph chemistry profiles and tissue glycogen are potential biomarkers for nonlethally monitoring stress in mussels. We sampled three species in the Flint River Basin over 2 years to evaluate how these hemolymph and tissue biomarkers responded to environmental changes. We used hierarchical linear models to evaluate the relationships between variation in the biomarkers and environmental factors and found that the responses of the hemolymph and tissue parameters were strongly related to stream discharge. Shifts in alanine aminotransferase and glycogen showed the largest relations with discharge at the time of sampling, while magnesium levels were most explained by the discharge for 5 days prior to sampling. Aspartate aminotransferase, bicarbonate, and calcium showed the strongest relations with mean discharge for 15 days prior to sampling. The modeling results indicated that biomarker responses varied substantially among individuals of different size, sex, and species and illustrated the value of hierarchical modeling techniques to account for the inherent complexity of aquatic ecosystems.

scholarly journals From Exploratory Tunnel to Base Tunnel: Hard Rock TBM Performance Prediction by Means of a Stochastic Approach

2020 ◽  
Vol 53 (12) ◽  
pp. 5473-5487 ◽  
Author(s):  
Andrea Rispoli ◽  
Anna Maria Ferrero ◽  
Marilena Cardu
Keyword(s):  
Performance Prediction ◽  
Early Stage ◽  
Tunnel Boring Machine ◽  
Stochastic Approach ◽  
Critical Issue ◽  
Utilization Factor ◽  
Tbm Performance ◽  
Factors Affecting ◽  
Tunnel Section ◽  
Input Variables

AbstractTunnel boring machine (TBM) performance prediction is often a critical issue in the early stage of a tunnelling project, mainly due to the unpredictable nature of some important factors affecting the machine performance. In this regard, deterministic approaches are normally employed, providing results in terms of average values expected for the TBM performance. Stochastic approaches would offer improvement over deterministic methods, taking into account the parameter variability; however, their use is limited, since the level of information required is often not available. In this study, the data provided by the excavation of the Maddalena exploratory tunnel were used to predict the net and overall TBM performance for a 2.96 km section of the Mont Cenis base tunnel by using a stochastic approach. The preliminary design of the TBM cutterhead was carried out. A prediction model based on field penetration index, machine operating level and utilization factor was adopted. The variability of the parameters involved was analysed. A procedure to take into account the correlation between the input variables was described. The probability of occurrence of the outcomes was evaluated, and the total excavation time expected for the tunnel section analysed was calculated.

Environmental factors affecting reproducibility of bioremediation field assays in Antarctica

2020 ◽  
Vol 169 ◽  
pp. 102915 ◽  
Author(s):  
L.M. Martínez Álvarez ◽  
L.A.M. Ruberto ◽  
J.M. Gurevich ◽  
W.P. Mac Cormack
Keyword(s):  
Environmental Factors ◽  
Factors Affecting
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