Breeding Ponds Research Articles

Prescribed fire and natural habitat characteristics affect crawfish frog (Rana areolata) advertisement call transmission

ABSTRACT For acoustically signalling animals, the rate of signal degradation is critical for successful communication. Degradation is heavily influenced by habitat characteristics, with sound degrading more rapidly in the presence of environmental obstacles (e.g. vegetation). Land management strategies such as prescribed burns eliminate obstacles and should therefore lead to more efficient sound transmission. Crawfish frogs (Rana areolata) produce long-distance advertisement calls for breeding. Habitats surrounding crawfish frog breeding ponds vary in vegetative density, and prairies surrounding breeding habitat often undergo controlled burns prior to the breeding season. We hypothesised that R. areolata advertisement calls would transmit more efficiently in post-burned prairies compared to other more vegetated habitats. To test this hypothesis, we conducted a sound transmission playback experiment, broadcasting crawfish frog calls in three habitats: forest, prairie, and post-burned prairie. We compared sound degradation measures between habitat types and across distances. We found that crawfish frog calls experienced up to 6.8 dB less excess attenuation in post-burned habitats relative to other habitat types, and that in general, prairie habitats had better sound transmission than forest. These results indicate that land management and habitat structure have consequences for acoustic communication, and may also influence the findings of frog call detection surveys.

Identification of novel Tet(X6)-Tet(X2) recombinant variant in Elizabethkingia meningoseptica from a bullfrog farm and downstream river in China.

The dissemination of strains producing tetracyclines monooxygenase Tet(X) from breeding farms to the natural environment poses a potential threat to public health. Antimicrobial susceptibility testing and WGS were performed to identify resistance phenotypes and genotypes. Cloning experiments, sequence alignment, and homology modeling were used to characterize the function and formation mechanisms of the recombinant variant. The mobilization potential of Tet(X) was assessed by collinearity analysis, conjugation experiments, and phylogenetic analysis. Three tet(X)-producing Elizabethkingia meningoseptica strains were isolated from bullfrog breeding ponds, the sewage outlet, and downstream river in Zhejiang Province, China. These strains carry a novel Tet(X) variant, differing from Tet(X6) by seven residues, and possess the ability to degrade tetracyclines. Interestingly, the novel Tet(X) is a recombinant variant formed by homologous recombination of Tet(X6) and the C-terminal of Tet(X2). Further analysis revealed that Tet(X6) formed several Tet(X) variants, including Tet(X5), through homologous recombination. The novel tet(X) gene is located on a circularizable integrative and conjugative element (ICEEmeChn3), with ISwz1 participating in the recombination of its multi-drug resistance region, potentially facilitating the mobilization and recombination of tet(X) in early hosts. These three strains were clonally transmitted and shared a close genetic relationship (SNP < 62) with a clinically-sourced strain isolated from the same province. To our knowledge, this is the first report of homologous recombination between Tet(X) variants with differing activities. These clonal strains provide evidence of the transmission of tet(X)-positive strains from aquaculture sewage to the natural environment, highlighting the need to strengthen the monitoring and management of this emerging farming model.

Effects of the photovoltaic fishery culture model on muscle nutritional quality and volatile flavor compounds of Litopenaeus vannamei

This study used Litopenaeus vannamei to compare the muscle nutritional quality and volatile flavor compounds of animals raised in the photovoltaic fishery culture model (PM) and the common pond breeding model (CM). Amino acids, fatty acids, and volatile flavor substances were identified and analyzed using an automatic amino acid analyzer and headspace solid phase microextraction(HS-SPME) combined with GC/MS. There were no significant differences between the two culture models in terms of general nutrients, mineral contents, and amino acid compositions in the muscles of L. vannamei. In the PM group, the proportion of flavor amino acids in total amino acids was higher. Based on the amino acid score (AAS) and chemical score (CS), it was found that methionine and cystine were the first limiting amino acids in the muscle samples. The essential amino acid index (EAAI) value was approximately 77 for both models, indicating high-quality proteins. The muscles contained nine types of fatty acids, with the PM group showing significantly higher levels of both monounsaturated and total fatty acids. A total of 23 volatile flavor compounds were identified in both models. The contents of 1-nonanal, n-tridecane, and alpha-terpineol were higher when cultured in the PM. Conversely, the contents of hexanal, 2-ethylhexanol, and dipentene were lower in the PM group. The photovoltaic fishery culture model has the potential to enhance income through photovoltaic power generation. In addition, this study found that the fatty acid composition of L. vannamei was improved in the PM, without compromising muscle composition or flavor. These results provide a theoretical basis for evaluating the meat quality of L. vannamei under different culture models and offer data to support and guide the promotion of the PM.

Effects of Synthetic Hormones on Fertilization, Fecundity, Hatching and Gonado-Somatic Index of Giant Snakehead (Channa Marulius) in Captivity

The effects of a crude protein (40% CP) diet on the spawning performance of giant Snakehead (Channa marulius) broodstock were assessed in this study through a three-week feeding trial. Mature C. marulius brood stock (N = 36) was taken from the brooders pond and stocked into nine small experimental breeding ponds, each measuring 4mx2mx1.5m (LxWxD). Following acclimatization, all male and female C. marulius broodstock with an average weight of 1.5–2.5 kg BW and a length of 70 cm were removed from the small breeding ponds. The current study's objective was to induce breeding in C. marulius by injecting synthetic hormones intramuscularly and monitoring fertilization, fecundity, hatching, and gonado-somatic index. Using a completely randomized design (CRD), nine fishponds were split into three treatments (T1, T2, and T3) during the study period, each with three replicates. In addition to evaluating the effects of artificially applied hormones, Conceptal® (T1), Suprefact® (T2), and Ovaprim® (T3), this study aimed to comprehend the reproductive biology of C. marulius. The hormones were injected into the test fish at the following proportion (0.3ml, 0.4ml and 0.5ml to male and 0.8ml, 0.9ml and 1.0ml to female’s ml/kg body weight) and then released into the earthen ponds for large scale production of seed. Two-way analysis of variance (ANOVA) was used. The results showed no successful spawning on Conceptal®. The gonado-somatic index (GSI) estimates for the study period showed that Suprefact had the highest average GSI values for both males and females (3.32±1.62% and 1.67±0.18%, respectively), followed by Ovaprim (1.13±0.56 and 1.22±0.68, respectively). Absolute fecundity was also estimated. The result showed that fish stimulated with suprefact (T2) obtained the highest average fecundity (3079.3±100.7%), fertilization rate (96.33±1.20%), hatching rate (94.67±2.40%), and survival rate (95.75±1.51%), then in ovaprim fecundity rate (1669.3±836.5%), fertilization rate (58.00±29.02), hatching rate (61.27±30.65), survival rate (64.67±32.34%), respectively. In conclusion, the use of Suprefact® and Ovaprim® can optimise the results of C. marulius breeding induction in small experimental breeding ponds, ensuring higher-quality eggs and a greater number of normal larvae.

Sampling through space and time: multi-year analysis reveals dynamic population genetic patterns for an amphibian metapopulation

Metapopulations are dynamic, and population genetics can reveal both spatial and temporal metapopulation variation. Yet, population genetic studies often focus on samples collected within a single time period or combine samples taken across time periods due to limited resources and the assumption that these approaches capture patterns and processes occurring over decadal and longer temporal scales. However, this may leave important fine-scale temporal variation in genetic composition undetected, particularly for metapopulations in which dynamic populations are expected. We investigated temporal patterns of population genetic diversity, effective population size, and differentiation across three sample periods for a dryland amphibian metapopulation. We sampled nine distinct Arizona treefrog (Hyla (Dryophytes) wrightorum) breeding ponds in 2014, 2018/2019, and 2021 and genotyped 17 microsatellite loci to quantify spatial and temporal population genetic dynamics. Genetic diversity within and between populations varied significantly among years. Most notably, we identified a concerning decline in allelic richness across populations, with an average − 26.11% difference between a population’s first and last sample period. Effective population sizes were generally small (Ne < 100) and variable within and among populations over time, with many populations falling below common conservation thresholds by the final sample period. Trends in global genetic diversity, as measured by heterozygosity, and population differentiation were relatively consistent across all sampling periods. Overall, we found that “snapshot” or single-time sampling approaches may miss temporal variability in genetic composition that has important conservation implications, including early warning signs of decline in genetic diversity.

Greater Glasgow pond amphibian surveys 2022

In 2019, Clyde Amphibian and Reptile Group (CARG) decided to organise a spring 2020 common frogspawn (Rana temporaria) survey of the Greater Glasgow area, Scotland. The COVID-19 lockdown postponed this project until 2022. The 2022 survey area was spread across four council districts: Glasgow City, South Lanarkshire, Renfrewshire and East Renfrewshire. The primary aim of the surveys was to collect records of amphibian breeding throughout the Greater Glasgow Area, with secondary aims of: (1) revisiting the ponds to see if the ponds supported the spawn through to tadpole and froglet stages; (2) assessing the condition of the ponds for amphibians; (3) identifying areas for habitat enhancement work; and (4) collecting data on breeding common toads (Bufo bufo) and newts (Lissotriton, Ichthyosaura and Triturus spp.). A total of 45 volunteers participated in the surveys. Surveys were completed between March and May 2022, with a primary focus between March and April in order to capture frog spawning data. Surveyors were asked to record amphibian population data, and habitat data in order to estimate Habitat Suitability Indices. In total 162 ponds were surveyed, with evidence of breeding common frogs found in 66.1% of ponds with 11,478 frogspawn clumps counted on the first set of surveys. Only 12.2% of ponds were found to contain common toads, and small newts (Lissotriton spp.) were identified in only 7.4% of ponds. In relation to the quality of breeding habitat, 24.5% of ponds were assessed as drying out annually, which significantly reduces the suitability of these ponds for breeding. This figure is predicted to increase with anthropogenic climate change reducing the number of breeding ponds available to amphibians in the absence of intervention. Furthermore, the majority of the ponds surveyed were assessed as offering poor or below average suitability for great crested newts (Triturus cristatus) and nearly half of the ponds surveyed were found to have poor or bad water quality, which can increase stress levels for larval amphibians and may adversely affect mortality levels. However, as the analysis of water quality was subjective, these findings should be treated with caution.

Spatial prioritisation for crested newt conservation in Luxembourg: Insights from population genetics and species distribution modelling

Abstract The intensification of agriculture and urbanisation has precipitated the decline of numerous species, including the northern crested newt (Triturus cristatus). To mitigate the impacts of habitat degradation and loss, restoration initiatives depend on evidence‐based decision‐making to identify priority sites for conservation efforts. Here, we employed a multidisciplinary approach, drawing on population genetics, species distribution modelling (SDMs) and landscape genetics to develop a spatial prioritisation framework for the creation and/or restoration of crested newt breeding ponds in Luxembourg. For the genetic analyses, more than 1000 crested newts from 98 ponds across Luxembourg were genotyped at 15 microsatellite loci to assess genetic diversity and spatial clustering. The relationship between newt presence and environmental variables was evaluated using SDMs. Priority restoration areas were identified with PRIORITZR, integrating genetic diversity, habitat suitability and connectivity. The population genetic structure was characterised by spatial clustering, which followed an isolation‐by‐distance pattern. Five sites were identified as significantly differentiated from the remaining populations, warranting targeted conservation efforts. Standing water bodies and proximity to the nearest occupied pond were the most important predictors of crested newt presence. The highest gain in habitat suitability through the creation of new ponds was predicted to occur in southwest Luxembourg. Based on the country‐wide predicted occurrence of crested newts and gains in habitat suitability, areas of highest restoration potential were identified in close proximity to existing crested newt populations. The produced maps of priority restoration areas should inform future conservation efforts of the crested newt in Luxembourg. While the importance of preserving genetic diversity is widely recognised, the theory‐practice gap frequently precludes the incorporation of genetic aspects into in situ conservation measures or management policies. This case study demonstrates the integration of multidisciplinary analyses within an evidence‐based framework to guide species conservation efforts.

In Search of Suitable Breeding Sites: Habitat Heterogeneity and Environmental Filters Determine Anuran Diversity of Western Madagascar

Environmental filtering shapes animal communities by preventing the colonization and persistence of certain species in a given habitat. More heterogenous environments are presumed to support a greater number of species and, consequently, increased species diversity, as environmental filters are also likely more heterogenous. Amphibians are especially sensitive to environmental influences due to distinct characteristics like permeable skin and low mobility. By analyzing the species richness and assemblage composition of tadpoles in 132 breeding ponds, we examined how the interplay of environmental variables shapes anuran species assemblages in breeding habitats of the dry forest of Western Madagascar. We found that environmental filtering is prevalent and habitat heterogeneity not only increases larval species richness but also alters species composition between these assemblages. Our study highlights the need for conserving heterogenous habitats to maintain local diversity. Furthermore, we recommend including multivariate modelling approaches to conservation efforts to acknowledge differences between specific habitats and beta diversity.

НАУКОВО-ПРАКТИЧНИЙ АНАЛІЗ СТАНУ ПРИРОДНОЇ КОРМОВОЇ БАЗИ СТАВІВ ПІВЛНЯ УКРАЇНИ НА ФОНІ ТРАНСФОРМАЦІЙ АБІОТИЧНИХ ТА БІОТИЧНИХ ЧИННИКІВ

Conducted research on the basis of the breeding ponds of the Kherson production and experimental plant for breeding of the ordinary fish indicate atypical dynamics of the development of the components of the natural feed base. Such aspects form a low fod

Extreme rainfall flushes out tadpoles of the yellow-bellied toad Bombina variegata from its breeding ponds.

Extreme rainfall flushes out tadpoles of the yellow-bellied toad Bombina variegata from its breeding ponds.

Managing invasive hybrids with pond hydroperiod manipulation in an endangered salamander system.

When invasive and endangered native taxa hybridize, the resulting admixture introduces novel conservation challenges. Across a large region of central California, a hybrid swarm consisting of admixed endangered California tiger salamanders (CTS) (Ambystoma californiense) and introduced barred tiger salamanders (BTS) (Ambystoma mavortium) has replaced native populations, threatening the genetic integrity of CTS and the vernal pool systems they inhabit. We employed a large-scale, genomically informed field experiment to test whether shortening breeding pond hydroperiod would favor native CTS genotypes. We constructed 14 large, seminatural ponds to evaluate the effect of hydroperiod duration on larval survival and mass at metamorphosis. We tracked changes in non-native allele frequencies with a 5237-gene exon capture array and employed a combination of custom Bayesian and generalized linear models to quantify the effect of pond duration on salamander fitness. Earlier work on this system showed hybrid superiority under many conditions and suggested that hybrids are favored in human-modified ponds with artificially long hydroperiods. Consistent with these earlier studies, we found overwhelming evidence for hybrid superiority. Very short hydroperiods substantially reduced the mass (1.1-1.5 fold) and survival probability (10-13 fold) of both native and hybrid larvae, confirming that hydroperiod likely exerts a strong selective pressure in the wild. We identified 86 genes, representing 1.8% of 4723 screened loci, that significantly responded to this hydroperiod-driven selection. In contrast to earlier work, under our more natural experimental conditions, native CTS survival and size at metamorphosis were always less than hybrids, suggesting that hydroperiod management alone will not shift selection to favor native larval genotypes. However, shortening pond hydroperiod may limit productivity of hybrid ponds, complementing other strategies to remove hybrids while maintaining vernal pool ecosystems. This study confirms and expands on previous work that highlights the importance of hydroperiod management to control invasive aquatic species.

State of the Art and Contribution to the Documentation on Fishing, Aquaculture and on the Microbiological Profile of Clarias Gariepinus and Oreochromis Niloticus Two Species of Fish Reared in the Whedos of the Upper Ouémé Delta in the Republic of Benin

Fish is an important source of animal protein in Africa and is used in the composition of several national dishes. This literature review examines fishing, aquaculture and fish reared in the whèdos of the upper Ouémé delta in Benin. It addresses socio-economic aspects, nutritional importance and traditional fish preservation technology. The sources of information used are publications, books, reports of dissertations and theses and technical notes. It was found that Clarias gariepinus and Oreochromis niloticus, among others, are two species of fish most often raised in the whèdos of the Ouémé River in Benin. These fish adapt to large variations of ecological factors of the aquatic environment found everywhere in Africa and reproduce easily in captivity, which favors their breeding in ponds. These species present multiple fish farming qualities: resistance to high densities, resistance to diseases and low oxygen levels, easy adaptation to artificial feeding and high growth. Microbiological contamination of fish flesh occurs only after capture and can be endogenous or exogenous contamination. Generally, several processes are used to overcome this problem of contamination of fish. Hot smoking and drying are very often used. The lack of hygiene in the traditional technology of smoking fish sometimes favor a considerable microbial contamination of the obtained products. Thus, contaminated fish can be the cause of foodborne diseases such as food poisoning. Most of the pathogenic strains responsible for these diseases are resistant to certain antibiotics.

Numerical study on the performance of circular juvenile fish breeding ponds

Due to the recent tendency to use circular ponds of closed-circuit systems in the fish farming industry, it seems necessary to investigate the flow pattern performance for improving water hydrodynamic behavior considering the input conditions. Although pond inflow conditions play a major role in the formation of rotational flow, in most cases, these ponds cannot be optimally used due to a lack of appropriate solutions. Therefore, this study presents the computational fluid dynamics model of a circular fish farming pond with a volume of 1.57 m3 based on incompressible steady Reynolds averaged Navier-Stokes formation using a realizable K-ε viscous model. Numerical modeling of the angle change of pond inflow is put on the agenda at three levels, and the inflow momentum force is considered at four levels to investigate vortex formation and its effect on the efficiency of ponds. The results indicate TKE is directly correlated with the inflow momentum force. In the case of injecting the flow tangentially to the pond wall, the maximum TKE is observed in the areas tangential to the pond wall. The formed vortices are analyzed using two vortex quantification methods of vortex strength and normalized velocity. The results demonstrate the maximum vortex strength is at 20–40% of the water level when injecting the flow tangentially into the pond wall (α3 = 30°). The model results suggest installing inlet nozzles tangentially to the pond wall and adjusting inflow with the minimum momentum force to improve rotational flow hydrodynamic performance.

Differential effect of dehydration on the voluntary activity of a diurnal toad

Anuran amphibians' ability to maintain their activity at high temperatures or low humidity depends on their capacity to face dehydration, especially when they display diurnal and terrestrial life habits. Melanophryniscus rubriventris is a diurnal and terrestrial toad from humid Yungas Andean forests that breeds in temporary ponds. It is exposed to the recurrent risk of dehydration because of pond desiccations during the breeding season. Here, we study how M. rubriventris males behaviorally respond to dehydration by measuring their voluntary activity under an ex-situ experiment. Toads with different hydration levels were exposed to a circular track for voluntary activity measurements. Dehydrated males of M. rubriventris toads did not adopt a water-conserving posture staying active during the test and increasing walking under severe dehydration. Certain tolerance to dehydration would allow performing daily activities under challenging diurnal conditions. The increased walking under severe dehydration suggests water or shelter-seeking behavior that would be crucial for diurnal and terrestrial toads to overcome the unpredictable hydric environment during the breeding season.

Transcriptome analysis of germ cell changes in male Chinese mitten crabs (Eriocheir sinensis) induced by rhizocephalan parasite, Polyascus gregaria

The parasitism by Polyascus gregaria on Eriocheir sinensis induces feminization of the appearance of male crabs, misleading fishermen to bring them to the breeding ponds as female crabs to cultivate broodstock selection. However, there are few studies on whether P. gregaria feminizes the male germ cells, resulting in a decline in the fecundity of male crabs. Therefore, this study aims to clarify the changes in gene expression levels of male crab testes after being parasitized by P. gregaria through transcriptome sequencing to evaluate the change in fecundity. We selected parasitized and healthy male crabs from a pond culture for comparison of gene expression in germ cells. The results showed that, compared with healthy male crabs, there were 104 genes with significantly different expressions, of which 79 were up-regulated and 25 were down-regulated. These genes are mainly focused on the cytoskeleton pathway in cell components and cellular protein complex assembly in biological processes. Several spermatogenesis-related genes, such as Kazal-type protease inhibitor, which inhibits gelatinolytic activities of sperm proteases, and juvenile hormone esterase 6, which degrades methyl farnesoate, were up-regulated; while the down-regulated expression of certain heat shock proteins may lead to spermatogenic dysfunction. In addition, some immune-related genes, such as double whey acidic protein domain-containing protein and serine proteinase inhibitor 3, were significantly up-regulated. These results indicated that P. gregaria changed the development process and cell structure of male host germ cells to inhibit sperm proliferation and maturation, while multiple immune pathways in the hosts were activated to resist P. gregaria invasion.

Size Estimation for Shrimp Using Deep Learning Method

Shrimp farming has been becoming a new source of income for fishermen in South Korea. It is often necessary for fishers to measure the size of the shrimp for the purpose to understand the growth rate of the shrimp and to determine the amount of food put into the breeding pond. Traditional methods rely on humans, which has huge time and labor costs. This paper proposes a deep learning-based method for calculating the size of shrimps automatically. Firstly, we use fine-tuning techniques to update the Mask RCNN model with our farm data, enabling it to segment shrimps and generate shrimp masks. We then use skeletonizing method and maximum inscribed circle to calculate the length and width of shrimp, respectively. Our method is simple yet effective, and most importantly, it requires a small hardware resource and is easy to deploy to shrimp farms.

Restricting living space: Development and larval morphology in sticky frogs (Microhylidae: Kalophrynus) with different reproductive modes

We compare reproductive features, development, and larval morphology in three closely related species of sticky frogs (Kalophrynus Tschudi, 1838) inhabiting the lowland and mountain forests of Vietnam and displaying a variety of reproductive modes. While K. interlineatus breeds in open temporary ponds, K. honbaensis and K. cryptophonus are phytotelm-breeders using tree hollows and bamboo stems for reproduction. Their tadpoles also differ in trophic specialization: larval K. interlineatus are typical suspension-feeders, whereas K. honbaensis and K. cryptophonus are obligatorily oophagous. All three species differ in egg and clutch sizes, duration of embryonal period and hatching stage, and the structure of the larval digestive tract and skeleton. Based on external and internal morphology, we conclude that tadpoles of K. interlineatus and K. cryptophonus represent two “extremes” of the adaptive spectrum of microhylid larvae, while K. honbaensis displays a set of transitory traits. Relying on these new findings in anuran biology, we discuss reproductive, ontogenetic, and morphological rearrangements during the transition from pond breeding to phytotelm breeding and from microphagy to macrophagy as well as the significance of the revealed adaptations to different habitats and larval life modes.

There's No Place Like Home: Influential Habitat Characteristics of Eastern Tiger Salamander (Ambystoma tigrinum tigrinum) Breeding Ponds in Maryland and Delaware

Habitat loss, degradation, and modification are important drivers of global population declines in amphibians. Most amphibians have a biphasic lifestyle and are susceptible to threats in both aquatic and terrestrial habitats. Eastern Tiger Salamanders (Ambystoma tigrinum tigrinum) are endangered throughout much of their range in the eastern United States, including Maryland and Delaware. Ambystoma t. tigrinum breed in ephemeral freshwater ponds and then migrate into the surrounding terrestrial environment after metamorphosis. Limited research exists about what habitat characteristics play a role in breeding pond use. We sought to understand what features of the breeding pond and surrounding landscape influence abundance and occupancy. We measured salamander occupancy, salamander abundance, and water quality parameters at ponds during the 2018 and 2019 breeding seasons. We used geographic information systems to determine pond area and the percentage of forest area and road density surrounding a pond at four spatial scales. Pond occupancy by A. t. tigrinum was positively associated with increased depth and less forest cover at the largest spatial scales. Abundance of A. t. tigrinum was greatest in larger, deeper ponds, potentially because these factors increase hydroperiod. More basic pH and decreased conductivity were also associated with higher male salamander abundances in ponds. Forest area and road density were not in the top-ranked model, although we note that ponds in this study had a minimum of 70% forest area within 150 m. Our findings elucidate relationships between A. t. tigrinum and their habitat, providing knowledge for future management of this state-endangered species.

Temporal and spatial variations in local sex ratios in a suburban population of the European green toad Bufotes viridis

BackgroundSex ratios of animal populations are important factors of population demographics. In pond-breeding amphibians, the operational sex ratio (OSR) among the breeding population is usually male-biased. Also, in European green toads (Bufotes viridis), males usually outnumber females at breeding sites, while the sex ratio of the total adult population (ASR) is assumed to be balanced. It has been suggested that sex-specific breeding behavior causes male-predominance at the breeding sites. We used a dataset of 5 years of street patrols to test this hypothesis. For this we analyzed local sex ratios of green toads in terrestrial habitats and at two artificial breeding ponds. We expected temporal and/or spatial changes of local sex ratios which would indicate sex dependent differences in breeding behavior.ResultsOverall observed ASR among 2111 green toads, counted in the course of street patrols from 2016 to 2020, was slightly male-biased (ASR = 0.56, annual ASRs = 0.49–0.63). Based on the data of 1631 toads (920 males, 711 females) captured within a radius of 300 m around nine main breeding sites, temporal and spatial variations in local ASRs were evaluated. Resulting values were compared to the calculated OSR at two artificial breeding ponds in 2021 (645 adult: 553 males, 92 females). Estimates predict more equally distributed females and males prior to the main breeding season. During breeding season, males predominated at both breeding sites (B1: 0.83, B2: 0.89), whereas females are estimated to outnumber males in terrestrial habitats. Proportions of females highly significantly increased with advancing time of the year and increasing distance to the breeding sites. While males tended to accumulate in proximity to water bodies, females dispersed soon after breeding to more distant areas.ConclusionsObserved sex ratios in the studied green toad population changed with time and sampling site, deviating from the population-wide sex ratio. Expanding sampling effort in amphibian conservation assessments in time and space, i.e., outside the main breeding season and away from the breeding sites, would be important to encompass such variations.

Study on Growth of Silver Carp (Hypophthalmichthys Molitrix) fed by Diatoma Microalgae in Pond

The common method of fertilizing to increase live food (microalgae) in Hypophthalmichthys molitrix ponds has disadvantages, including the fact that fertilizers increase the population of microalgae of all types (toxic and non-toxic) without human control and thus can cause growth. Unwanted to become harmful algae. This study was carried out at the same time with the beginning of the summer season and breeding of silver carp, with the aim of enriching the microalgae composition of warm-water fish breeding ponds located in Mazandaran province. Growth rate was calculated according to the treatments. 100 young of 90g Silver Carp were stored in each pond. Experiments were performed in circular concrete ponds with a diameter of 6 meters and a water height of 1 meter. Different microalgae compositions (1: 70% chlorella, 30% diatoma, 2: 70% diatoma, 30% chlorella and 3: control of natural algae composition of the area) were fed during the experiment. In this study, the growth rate of Silver Carp in different densities of Diatoma and Chlorella algae was evaluated in combination with different percentages in the pond environment and at the end of the experiment, survival percentage, fish growth rate, specific growth rate and average daily growth were calculated. Ponds whose fish were water-enriched with Diatoma microalgae with a density of 70% had higher growth (survival rate, fish growth rate, specific growth rate and average daily growth). Also, according to this study, since one of the condition for having a healthy farmed fish is to have a healthy and proper nutrition, so it is necessary to increase the share of edible microalgae Diatoma in the breeding environment of these fish to produce more and higher quality of these fish.