Temporal Fluctuations in Abundances of Anuran Amphibians in a Seasonal Amazonian Rainforest

Plankton is an aquatic biota that lives following the currents in the water. The life of plankton is highly dependent on the water quality in those aquatic environments. The constantly changing physical and chemical conditions of water lead to fluctuations in the abundance of plankton in a water. This study aims to analyze fluctuations in plankton abundance and its correlation with water quality in Percut Sei Tuan Waters. The study was conducted in February and March 2023. Filtration method at 3 stations is the Sampling technique used in this study. The sampling period is carried out in the morning, afternoon, and evening. Data analysis to determine the relationship between variables using Pearson correlation in SPSS version 26. Based on the research results, 42 genera of phytoplankton and 16 genera of zooplankton were found. The highest abundance of phytoplankton was 4.635 Ind/L during the afternoon. The highest abundance of zooplankton was obtained at evening, which was 1.049 Ind/L. This is due to the daily vertical migration of zooplankton and their negative phototactic behavior, while phytoplankton require light for photosynthesis. The research results indicate that the abundance of phytoplankton has a very strong correlation with temperature, light intensity, salinity, TSS, pH, DO, and Nitrate. The abundance of zooplankton is highly correlated with water flow velocity, light intensity, salinity, TSS, TDS, pH, DO, Nitrate, and Phosphate.

AimPatterns of diversity along elevational gradients are driven by species characteristics but remain poorly understood. Filling this gap is imperative given the deteriorating conservation status of anurans worldwide. Here, we examine frog diversity and species composition along a sharp subtropical elevational gradient and assess the degree to which these are determined by environmental and spatial predictors.LocationAn extensive southern Brazilian Atlantic Forest elevational gradient ranging from 300 to 1,800 m above sea level.MethodsWe sampled 38 ponds and used structural equation modelling to examine the direct and indirect effects of area, climate, habitat amount, habitat complexity and productivity on frog species richness and abundance. We also applied joint species distribution models to investigate the importance of these predictors on frog species composition using species distribution and co‐occurrence along the elevational gradient.ResultsWe recorded 12,636 individuals of 41 frog species. Frog species richness was highest at intermediate elevations, showing a hump‐shaped pattern. Frog abundance was highest at lowlands and decreased towards higher elevations. We found support for only the habitat amount hypothesis in explaining overall species richness. Although temperature had a positive influence on productivity and frog abundance, neither predictors were related to species richness. Species composition diverged markedly between lowland and highland frog assemblages, which was mainly attributed to differences in ambient temperature.Main conclusionElevations containing more extensive natural habitat areas retained the most species‐rich frog assemblages. The mid‐elevational peak is likely attributed to lowland habitat (<800 masl) heterogeneity and extreme climatic conditions in highland areas (>1,400 masl). The entire elevational gradient is, however, critical in maintaining anuran species diversity as lowland assemblages are distinct from those at mid‐ to high elevations. Our study also shows that anthropogenic habitat loss has a decisive effect on montane frog diversity, reinforcing the need to effectively protect these areas.

The abundance and size of the giant jellyfish (Nemopilema nomurai) medusae collected by midwater trawl from 2006 to 2017 in the northern East China Sea (nECS) were investigated. While absent in 2008 and 2011, in other years, medusae were prevalent in June and July, rare in October, and not found from January to May. This seasonality in medusa abundance might be related to the life cycle characteristics of this species, with strobilation occurring near Chinese coast of the nECS from late March to early June but medusae dispersing in oceanic currents or dying by early autumn. Peak abundances in June and July varied from 0 to 62.1 × 106 medusa m−2 in the repeatedly observed area (30°30′ N–31 °N, 124°15′ E–126 °E). These annual fluctuations in medusae abundance in the nECS roughly coincide with patterns in the Sea of Japan (JS) in the autumn, which suggests that monitoring in nECS would be effective in predicting the occurrence of this species in the JS which undergoes massive occurrences of this species. The medusae sizes were comparable in June, but smaller in 2006, 2007, 2009, and 2010 than that in 2012–2017 in July. Hence, the existence of a large annual variation in the size of N. nomurai even in the same area and period was indicated.

The composition, structure and temporal variation of ectomycorrhizal (EM) communities associated with mountain avens (Dryas octopetala) in grass heaths of the Burren, western Ireland were assessed by using soil core sampling in two permanent plots and 30 other sites (196 cores in total). Of the 34 different EM types observed, 11 were common and constituted over 80% of the EM biomass. Four EM types, Craterellus lutescens, Tomentella sp., Dryadirhiza fulgens and Cenococcum geophilum were the most abundant as measured by EM length and frequency of occurrence in cores. The species profile and relative abundances were very similar in cores from the permanent plots and different sites in the Burren, indicating that they were all representative of the same EM community. The below-ground EM community in both plots was compared with production of basidiomes, and the latter was found to be an unreliable indicator of EM community structure. Temporal variation in the EM community was assessed by repeated core sampling of the two permanent plots over a 14-month period (between March 1998 and May 1999). No statistically significant shifts in EM abundance were found between sampling dates, probably as a consequence of the large variation in EM abundance between core samples over the sampling period. No significant relationship was found between rainfall, soil moisture or soil temperature and fluctuations in EM abundance. Patterns of total EM abundance and fluctuations in EM diversity were strongly correlated between the two permanent plots over the sampling period. Temporal fluctuations in the dominant EM type, Craterellus lutescens, were similar in both plots with respect to mycorrhizal length, biomass and relative abundance, and the patterns between both plots were positively correlated. EM diversity was negatively correlated with biomass of ectomycorrhizas of Craterellus lutescens in both plots, but it was significant only in plot 1.

The question of what mechanisms maintain tropical biodiversity is a critical frontier in ecology, intensified by the heightened risk of biodiversity loss faced in tropical regions. Ecological theory has shed light on multiple mechanisms that could lead to the high levels of biodiversity in tropical forests. But variation in species abundances over time may be just as important as overall biodiversity, with a more immediate connection to the risk of extirpation and biodiversity loss. Despite the urgency, our understanding of the primary mechanisms driving fluctuations in species abundances has not been clearly established. Here, we introduce a theoretical framework based around life history; the schedule of birth, growth, and mortality over a lifespan, and its systematic variation across species. We develop a mean field model to predict expected fluctuations in abundance for a focal species in a larger community, and we quantify empirical life history variation among 90 tropical forest species in a 50 ha plot in Panama. Putting theory and data together, we show that life history provides a critical piece of this puzzle, allowing us to explain patterns of abundance fluctuations more accurately than previous models incorporating demographic stochasticity without life history variation, and without introducing unobserved couplings between species and their environment. This framework provides a starting point for more general models that incorporate multiple factors in addition to life history variation, and suggests the potential for a fine-grained assessment of extirpation risk based on the impacts of anthropogenic change on demographic rates across life stages.

A New Peruvian Styloceras (Buxaceae): Discovery of a Phytogeographical Missing Link

Translocated from their native range in the Americas in 1935, cane toads (Rhinella marina, Bufonidae) have now spread through much of tropical and subtropical Australia. The toad's invasion and impact have attracted detailed study. In this paper, I review information on ecological interactions between cane toads and Australian anurans. The phylogenetic relatedness and ecological similarity between frogs and toads creates opportunities for diverse interactions, ranging from predation to competition to parasite transfer, plus a host of indirect effects mediated via impacts of toads on other species, and by people's attempts to control toads. The most clear‐cut effect of toads on frogs is a positive one: reducing predator pressure by fatally poisoning anuran‐eating varanid lizards. However, toads also have a wide range of other effects on frogs, some positive (e.g. taking up parasites that would otherwise infect native frogs) and others negative (e.g. eating frogs, poisoning frogs, competing with tadpoles). Although information on such mechanisms predicts intense interactions between toads and frogs, field surveys show that cane toad invasion has negligible overall impacts on frog abundance. That counter‐intuitive result is because of a broad balancing of negative and positive impacts, coupled with stochastic (weather‐induced) fluctuations in anuran abundance that overwhelm any impacts of toads. Also, the impacts of toads on frogs differ among frog species and life‐history stages, and depend upon local environmental conditions. The impacts of native frogs on cane toads have attracted much less study, but may well be important: frogs may impose biotic resistance to cane toad colonization, especially via competition in the larval phase. Overall, the interactions between native frogs and invasive toads illustrate the diverse ways in which an invader's arrival can perturb the native fauna by both direct and indirect mechanisms, and by which the native species can curtail an invader's success. These studies also offer a cautionary tale about the difficulty of predicting the impact of an invasive species, even with a clear understanding of mechanisms of direct interaction.

Pseudis minuta is abundant in a variety of aquatic environments of the Pampa domain. Therefore, it can be considered a good model for testing hypotheses on environmental heterogeneity and the influence of climate on the activity of anurans. In this study, we examined the spatial distribution pattern of P. minuta in terms of microhabitats and the influence of abiotic factors on seasonal fluctuations in the abundance of this species. Samples were collected monthly from April 2008 to May 2009 in wetlands and coastal dunes in the Lagoa do Peixe National Park. A total of 112 specimens of P. minuta were collected, of which 45 were found in the wetland area and 67 in the dune area. The species showed seasonal fluctuation in abundance, and it was most abundant in months with higher temperatures (spring-summer). Pseudis minuta was mainly associated with aquatic vegetation, an expected pattern in terms of their morphological adaptations to this environment. Among the abiotic parameters analyzed, only the monthly mean temperature showed a significant correlation (p < 0.05; r = 0.67) with the abundance of P. minuta. We concluded that P. minuta is a generalist species with respect to microhabitat use and also that fluctuation in its population abundance is mainly associated with seasonal variation in temperature.

The structure, relative abundance and density of the anuran community of Cocha Cashu, in the amazonian rainforest of Peru (350 m, 11° 55' S, 71° 18' W, Manu National Park) was studied during 395 days of field work, from September 1985 to November 1989. The study compared the two major types of upper amazonian habitats, floodplain forest and upland forest. The entire assemblage is composed of 81 species (Table I). There are more diurnal species in the upland forest than in the floodplain forest. Although each type of habitat has twenty terrestrial species and twelve food specialists, mainly ant eaters, these guilds account for significantly different proportions on each of the assemblages (Tables II and III). Sixty six species (out of 71) were observed in 250 days of transect sampling in the floodplain, whereas 49 species were counted in only 55 days on the uplands (Fig. 9) ; ten of these species do not occur in the floodplain and 39 are common to both habitats. Although relative abundance curves of both habitats are similar (Fig. 1 0), relative abundances of the 39 shared species differ significantly for each type of habitat (Fig. 1 1). Most of the Anuran species are small. Mean males’ Snout-Vent-Length ranges from 13.5 mm in Eleutherodactylus cf. carvalhoi to 136 mm in Leptodac-tylus pentadactylus, and at least 80 % weigh less than 10 g (Table V). None of the species accounts for more than 1 5 % of the relative abundances in floodplain or in the upland, suggesting a rather equitable distribution of abundance. No significant differences between the two types of habitats were found in terms of numbers of species, grouped by mode of reproduction (Table V). However, when relative abundance of individuals grouped by mode of reproduction were compared, all but the species laying their eggs in vegetation overhanging water and those building terrestrial foam nests without free tadpoles, showed significant differences (Table VI). The Cocha Cashu floodplain data are compared to those from Santa Cecilia (Ecuador, 350 m, 0° 03' N 77°11'W), the richest site in Anuran species (87 species) until now. There are no differences in the number of species by mode of reproduction, but, except for the Dendrobatidae, all relative abundances of individuals by mode of reproduction differ significantly between the two sites (Tab. VII). Densities were estimated by two methods : 219 censuses of male calling activity of ten forest breeding species (Table VIII), and 80 forest litter plots. Densities estimated by these two methods did not coincide. Plots revealed an uneven distribution of frogs in the forest and densities similar to other amazonian sites, but lower than those estimated for Central America (Table XI). Although most species were observed on transects, pit-fall traps were effective on catching active nocturnal terrestrial species not easily observed by other methods (Table XII). None of the methods used here to estimate diversity or density are efficient enough to sample adequately the entire community. The possible causes of the anuran species richness at Cocha Cashu are briefly discussed. The number of species at Cocha Cashu and Santa Cecilia being very similar (respectively 81 and 87 species) despite the striking differences in rainfall regime between the two sites, high atmospheric humidity cannot be considered as the only determinant of the high species diversity of anurans in tropical rainforests. The importance of historical factors, and more particularly of the effect of river dynamics on the heterogeneity of the Upper Amazonian environment, is emphasized.

Effect of land use on anuran species composition in north-eastern KwaZulu-Natal, South Africa

By the use of an array of ten vertically-spaced antennas and a rotating wave guide switch, a portion of the height-gain pattern for a short radio path was obtained as a function of time for a wave length of 8.6 millimeters. In the analysis of the data taken across a small lake, the reflection from the water is assumed to be made up of two components. One component is a constant value equal to the median signal received at the antennas over the sampling period and the other component is a variable signal of the proper phase and magnitude to give the measured total signal at each instant. The angle of arrival, phase and magnitude of the fluctuating signal are obtained for a short sample of data and their characteristics described.

&#x0D; This study aims to determine the diversity of fish species and to analyze the condition of water quality in the Cipeles River, Summedang Regency, West Java Province, Indonesia. The research was conducted for one month. The research method used was census with purposive sampling technique. The sampling period is four times a week. Analysis of the data used in this study is the composition of fish species, relative abundance, diversity, and water quality with quantitative descriptive data analysis. The results showed that the fish caught were baung (Mystus cavasius), singaringan (Mystus singaringan), tilapia (Oreochromis niloticus), hampala (Hampala macrolepidota), paray (Rasbora aprotaenia), genggehek (Mystacoleucus marginatus), lalawak (Barbonymus balleroides), and and julung-julung (Dermogenys pusilla). The fish diversity index value 0,85 – 0,89 was categorized as low with the highest relative abundance of genggehek fish (Mystacoleucus marginatus) at stations I and III, and lalawak fish (Barbonymus balleroides) at station II. The native fish of the Cipeles River that was able to adapt from 2001 until now is M. marginatus.&#x0D;

Meganyctiphanes norvegica (M. Sars 1856), the northern krill, is the largest and most abundant euphausiid species in the northern hemisphere, where it represents a key component of many pelagic communities. Although planktonic, krill could be considered a nektonic organism, as it is capable of active movements. This behaviour may be adaptive, because it allows these organisms to maintain their geographic position, leading to stable population structure, despite being continuously exposed to the heterogeneous oceanic conditions. By means of single-strand conformation polymorphism and DNA sequencing, we analyzed allelic variation of the Subunit 1 of NADH dehydrogenase mtDNA locus in 23 populations of the northern krill Meganyctiphanes norvegica, from 15 locations spanning the distribution range of the species. Analysis of the data indicated that the genetic structure, as revealed by analysis of population samples collected at the same site in consecutive years, was stable during that sampling period. Our results revealed the existence of 4 genetically and geographically distinct gene pools of M. norvegica, 2 occurring in the NE Atlantic ('northern' NE Atlantic and 'southern' NE Atlantic), 1 in the NW Atlantic, and 1 in the Mediterranean (Ligurian) Sea.

Research background: Environmental factors are not adequately addressed in organizational ecology studies. At the same time, it is known that the theory has not received enough attention except for North America, which is the emerging point. Purpose: We aim to examine macroeconomic connectedness between the organizational ecology of transportation and storage firms and macroeconomic variables such as price and production indexes. Research methodology: This paper discusses the relation among the following variables within the framework of macroeconomic connectedness via organizational ecology theory. The variables are FOUNDINGS, DISBANDINGS, TRNSP-CPI, PPI IPI and ENERGY. We use the TVP-VAR based Diebold-Yılmaz Connectedness approach in the analysis of the data. Results: DISBANDING is the net transmitter throughout the entire period. FOUNDING is mainly a net shock receiver during the COVID-19 period and transmitter in other periods. TRANS-CPI and PPI are risk receivers throughout the entire period, and even the shocks they transmit increased in the post-2018 period. ENERGY and IPI are in shock receiver status throughout the entire period. The received shocks of IPI from others have decreased with the effect of the lockdown experienced during the COVID-19 period. Novelty: The investors can hedge against risk by looking at industry production capacity and the number of firm closures, considering the net bilateral link between the indices, and calculating the appropriate time period for establishing a firm. Connectedness indices vary considerably over the sampling period, which indicates that investors must dynamically adjust their position in the industry.

The effect of climatic conditions on the structure of populations has been perceived for different orders of insects and families of beetles. Here we described the population dynamics of Euspilotus azureus (Sahlberg, 1823) and determined its relationship with climatic variables. The specimens were collected monthly for one year in an area of Seasonal Semideciduous Forest, in Viçosa, Brazil. The seasonality of the population and of sexes was estimated through the absolute frequency of occurrence (AF) and the percentage frequency of occurrence (FO%) of the population and each sex, which were determined monthly. To test whether the changes in monthly AF of the population and of each sex are correlated with climatic variables, Spearman correlation tests were performed. To identify whether there are temporal fluctuations in the sex ratio, considering months and seasons, and within each season, we performed Chi-square tests. A total of 3,126 individuals (1,009 females and 2,117 males) were collected. The population had the highest abundance in spring and summer, and the lowest in autumn and winter. The highest AF and FO were found in December and January, and the lowest in June and July. The sex ratio of the population did not differ in the months of the year, but in the spring there was a marked predominance of males. For E. azureus, the temporal fluctuation in abundance of the population and in the sex ratio is related to the climatic variables of maximum temperature, humidity, and precipitation. Climatic variables, especially the temperature, provided a greater abundance of the population in the hottest and rainiest periods of the year for inducing reproductive activity and altering the population’s sex ratio.