CYCLICAL CHANGES IN THE TESTICULAR ACTIVITY OF THE LAKE CHUB, COUESIUS PLUMBEUS (AGASSIZ)

1966 ◽  
Vol 44 (2) ◽  
pp. 149-159 ◽  
Author(s):  
Syed Nazar Ahsan
Keyword(s):  
Environmental Factors ◽  
Water Temperature ◽  
Quantitative Evaluation ◽  
Annual Cycle ◽  
Day Length ◽  
Temperate Latitude ◽  
Histochemical Methods ◽  
Couesius Plumbeus

The cyclical changes in the activity of the testes of a teleost, the lake chub, from a north temperate latitude have been studied by histological and histochemical methods with a quantitative evaluation of the different spermatogenetic stages. The annual testicular cycle is divided into live stages and cyclical changes in the spermatogenetic activity have been related to the changing environmental factors, namely day length and water temperature. The annual cycle consists of a prolonged mitotic phase during the fall and winter, and a shorter meiotic phase during the spring. Lobule boundary cells have been examined and changes in their activity have been recorded. Continued spermatogenetic activity during spawning enables repeated spermiation, which is advantageous since the males are comparatively fewer than the females.

scholarly journals A Machine Learning Approach for Estimating the Trophic State of Urban Waters Based on Remote Sensing and Environmental Factors

2021 ◽  
Vol 13 (13) ◽  
pp. 2498
Author(s):  
Shijie Zhu ◽  
Jingqiao Mao
Keyword(s):  
Remote Sensing ◽  
Environmental Factors ◽  
Water Temperature ◽  
Trophic State ◽  
Trophic Levels ◽  
Water Bodies ◽  
Trophic State Index ◽  
Urban Water ◽  
Estimation Model ◽  
Input Variables

To improve the accuracy of remotely sensed estimates of the trophic state index (TSI) of inland urban water bodies, key environmental factors (water temperature and wind field) were considered during the modelling process. Such environmental factors can be easily measured and display a strong correlation with TSI. Then, a backpropagation neural network (BP-NN) was applied to develop the TSI estimation model using remote sensing and environmental factors. The model was trained and validated using the TSI quantified by five water trophic indicators obtained for the period between 2018 and 2019, and then we selected the most appropriate combination of input variables according to the performance of the BP-NN. Our results demonstrate that the optimal performance can be obtained by combining the water temperature and single-band reflection values of Sentinel-2 satellite imagery as input variables (R2 = 0.922, RMSE = 3.256, MAPE = 2.494%, and classification accuracy rate = 86.364%). Finally, the spatial and temporal distribution of the aquatic trophic state over four months with different trophic levels was mapped in Gongqingcheng City using the TSI estimation model. In general, the predictive maps based on our proposed model show significant seasonal changes and spatial characteristics in the water trophic state, indicating the possibility of performing cost-effective, RS-based TSI estimation studies on complex urban water bodies elsewhere.

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 Fleshy Red Algae Mats Influence Their Environment in the Mediterranean Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Neele Schmidt ◽  
Yusuf C. El-Khaled ◽  
Felix I. Roßbach ◽  
Christian Wild
Keyword(s):  
Environmental Factors ◽  
Light Intensity ◽  
Water Temperature ◽  
Mediterranean Sea ◽  
Water Column ◽  
Red Algae ◽  
Water Movement ◽  
Ecosystem Engineer ◽  
Overlying Water ◽  
The Mediterranean

In the Mediterranean Sea, the fleshy red alga Phyllophora crispa forms dense mats of up to 15 cm thickness, mainly located on rocky substrates in water depths below 20 m. Because of the observed density of these mats and some first observations, we hypothesize that P. crispa is a yet undescribed ecosystem engineer that provides a multitude of ecological niches for associated organisms along small-scale environmental gradients. Therefore, we conducted an in-situ pilot study in the Western Mediterranean Sea to assess potential influence of the algae mats on the key environmental factors water movement, temperature and light intensity. We comparatively and simultaneously measured in P. crispa mats, in neighboring Posidonia oceanica seagrass meadows, on neighboring bare rocky substrates without algae mats, and in the directly overlying water column. We used several underwater logging sensors and gypsum clod cards. Findings revealed that P. crispa significantly reduced water movement by 41% compared to the overlying water column, whereas water movement was not affected by P. oceanica meadows and bare rocky substrates. Surprisingly, P. crispa increased the water temperature by 0.3°C relative to the water column, while the water temperature in P. oceanica and on bare rocky substrates was reduced by 0.5°C. Light intensity inside the red algae mats was reduced significantly by 69% compared to the water column. This was similar to measured light reduction of 77% by P. oceanica. These findings highlight the strong influence of the dense red algae mats on some key environmental factors. Their influence is obviously similar or even higher than for the well-known seagrass ecosystem engineer. This may be a factor that facilitates associated biodiversity similarly as described for P. oceanica.

scholarly journals Habitat characteristics with an. barbirostris larva density in Bulukumba

2018 ◽  
Vol 73 ◽  
pp. 06019 ◽  
Author(s):  
Suryadi Iwan
Keyword(s):  
Environmental Factors ◽  
Water Temperature ◽  
Endemic Area ◽  
Larval Density ◽  
Breeding Habitat ◽  
Habitat Characteristics ◽  
Habitat Modification ◽  
Bivariate Analysis ◽  
P Value ◽  
Cross Sectional

Bulukumba is a malaria endemic area in South Sulawesi with malaria cases reported annually, An.barbirostris as a potential vector of malaria in the area. This study aims to analyze habitat characteristics with a density of An. barbirostris larvae The method used is an observational study with ecological survey design through the cross-sectional approach of samples in the form of Anopheles larvae habitat. Bivariate analysis shows physical, chemical, and biological environmental factors. water temperature significant to the density of larva An.barbirostris with p-value = 0,002. Multivariate test using linear regression to know the most influential variables, it is known that the variables that have the most influence on the density of larvae An. barbirostris in endemic area Bulukumba is water temperature p = 0,002. Environmental factors such as salinity, aquatic plant, plants around, predators and crops along with water temperature are factors that support the density of An. barbirostris larvae Control can be done with environmental management, especially interventions on Anopheles sp larvae breeding habitat, by sowing predator fish seeds, habitat modification and manipulation. modification of anopheles habitat by covering habitats and carrying out development can reduce larval nutrition so as to reduce carbon in the soil which results in a decrease in larval density.

Study on the Impact of Water Environmental Factors on Dominant Species of Phytoplankton around the Power Plant in Xiangshan Bay

2012 ◽  
Vol 610-613 ◽  
pp. 3371-3374 ◽  
Author(s):  
Hong Yang ◽  
Ying Zhao ◽  
Hui Rong Zhang ◽  
Gui Xiang Dai ◽  
Jun Ding ◽  
...  
Keyword(s):  
Power Plant ◽  
Environmental Factors ◽  
Statistical Model ◽  
Water Temperature ◽  
Temperature Increase ◽  
Dominant Species ◽  
Thermal Discharge ◽  
Xiangshan Bay ◽  
The Impact ◽  
Growth And Reproduction

The SPSS19.0 software was used to analyse the data of enclosure experiments last for 7 days in summer of 2011. Water temperature increase as a factor to establish the statistical model, and the response relation of thermal discharge warming and Coscinodiscus Jonesianus biomass was analyzed quantitatively. The results showed that, it would promote Coscinodiscus Jonesianus growth and reproduction with the water warming at 0.2°C to 0.79°C , which would be restrained at the water warming at 0.8°C to 2.0°C. When the water temperature increase 0.1°C, 0.4°C and 0.7°Cwill respectively result in Coscinodiscus Jonesianus biomass grow 216.12%, 72.87% and 15.05%. While the water temperature increase 1.0°C, 1.5°C and 2.0°C will respectively result in Coscinodiscus Jonesianus biomass reduce 6.38%, 17.95% and 26.17%.

scholarly journals DNA metabarcoding of zooplankton communities: species diversity and seasonal variation revealed by 18S rRNA and COI

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11057
Author(s):  
Lina Zhao ◽  
Xue Zhang ◽  
Mengyue Xu ◽  
Ying Mao ◽  
Yuan Huang
Keyword(s):  
Environmental Factors ◽  
Water Temperature ◽  
Total Nitrogen ◽  
Seasonal Changes ◽  
18S Rrna ◽  
Freshwater Ecosystems ◽  
Influential Factors ◽  
Diversity Assessment ◽  
Dna Metabarcoding ◽  
Sanmenxia Reservoir

Background Zooplankton is an important component of aquatic organisms and has important biological and economical significance in freshwater ecosystems. However, traditional methods that rely on morphology to classify zooplankton require expert taxonomic skills. Moreover, traditional classification methods are time-consuming and labor-intensive, which is not practical for the design of conservation measures and ecological management tools based on zooplankton diversity assessment. Methods We used DNA metabarcoding technology with two different markers: the nuclear small subunit ribosomal RNA (18S rRNA) and mitochondrial cytochrome c oxidase (COI), to analyze 72 zooplankton samples collected in 4 seasons and 9 locations from the Sanmenxia Reservoir. We investigated seasonal changes in the zooplankton community and their relationship with water environmental factors. Results A total of 190 species of zooplankton were found, belonging to 12 phyla, 24 classes, 61 orders, 111 families, and 174 genera. Protozoa, especially ciliates, were the most diverse taxa. Richness and relative abundance of zooplankton showed significant seasonal changes. Both alpha and beta diversity showed seasonal trends: the diversity in summer and autumn was higher than that in winter and spring. The zooplankton diversity was most similar in winter and spring. By correlating metabarcoding data and water environmental factors, we proved that water temperature, chemical oxygen demand, total nitrogen and ammoniacal nitrogen were the main environmental factors driving the seasonal changes in zooplankton in the Sanmenxia Reservoir. Water temperature, followed by total nitrogen, were the most influential factors. This study highlights the advantages and some limitations of zooplankton molecular biodiversity assessment using two molecular markers.

scholarly journals PENGARUH FAKTOR LINGKUNGAN TERHADAP KEBERADAAN GASTROPODA PADA EKOSISTEM MANGROVE DI DERMAGA LANTAMAL KELURAHAN KARANG INDAH DISTRIK MERAUKE KABUPATEN MERAUKE

2018 ◽  
pp. 33-48
Author(s):  
Rosiana Sari Mathius ◽  
Bonny Lantang ◽  
Modesta R. Maturbongs
Keyword(s):  
Environmental Factors ◽  
Data Collection ◽  
Water Temperature ◽  
Soil Ph ◽  
Field Data ◽  
Environmental Parameters ◽  
Mangrove Ecosystem ◽  
Field Data Collection ◽  
Water Ph ◽  
Temperature Water

This study aims to determine the type and effect of environmental factors on the presence of gastropods in the mangrove ecosystem. Field data collection is taken by measuring the environmental parameters directly, while gastropod data is obtained by calculating directly the amount obtained by each data collection. The results showed that in Lantamal Pier there were 8 species of gastropods : Littorina scabra, Cerithidea obtusa, Cassidula angulifera, Terebralia sulcata, Terebralia palustris, Ellobium aurisjudae, Telescopium-telescopium and Nerita lineata while environmental factors that affected to gastropods were water temperature, water pH, and soil pH.   Keywords: Gastropods; Environmental parameters.

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