Effects of active protection of the endangered fish lake minnow, Eupallasella (Rhynchocypris) percnurus (Pallas, 1814), on its occurrence in Mazowieckie Voivodeship in Poland

Knowledge of the historical occurrence of the endangered cyprinid fish species, Eupallasella percnurus (Pall.), in today's Kujawsko-Pomorskie Voivodeship in Poland is sparse. However, a total of nine sites inhabited by this species had been identified by the end of the twentieth century, but only one of theses had survived into the early 2000s. The largest field inventory to date of this area was undertaken from 2005 to 2011 and nine new sites were recorded. Most of the newly discovered sites inhabited by E. percnurus are located in the Dobrzynskie Lake District mesoregion, which is where this species has occurred in the past. Four of these sites have been designated as vulnerable and two as critically threatened. Immediate active protection measures are necessary to preserve E. percnurus at the two existing sites in the Special Protected Area PLH040013 Cyprianka.

This paper presents updated information on the past and present occurrence of the endangered cyprinid lake minnow, Eupallasella percnurus (Pall.), in Lubelskie Voivodeship in Poland. It includes an approximate assessment of threats to its existence and perspectives for its protection. The area of today's voivodeship was the largest national sanctuary for this species as early as in the 1950s; however, of 52 known historical sites, only seven are currently extant. Wide-ranging field inventories conducted in the voivodeship in 2002-2010 revealed the existence of 40 previously unknown sites. The present state of E. percnurus occurrence was assessed for 44 sites, nearly half of which are located in the Dorohuskie Depression mesoregion around the village of Siedliszcze. Only one site was confirmed in Poleski National Park. The sites in this region appear to be less endangered in comparison to those located in other Polish voivodeships with nearly 50% classified as threatened to a low degree. At present, 18 sites, or 40.9%, are under various forms of protection, mainly under the auspices of the European Ecological Natura 2000 Network.

The present paper summarizes all available scientific data on the historical and current occurrence of the endangered cyprinid fish species lake minnow, Eupallasella percnurus (Pall.), in Wielkopolskie Voivodeship in Poland. In the twentieth century, only three or four sites were identified in this part of the country. Today, there is only one site in the voivodeship situated in the vicinity of Wolsztyn, which is classified as highly threatened and is subject to protection under the European Ecological Natura 2000 Network as PLH300028 Bar³o?nia Wolsztynska. Although some findings of unknown sites of E. percnurus in Wielkopolska remain feasible, the prerequisite for the preservation of this species in this region is the urgent implementation of active protection measures. These should include an assessment of the present condition of the existing population, a partial deepening of the water bodies inhabited by this species, and searches for other water bodies nearby that are suitable for future introductions of wild or cultivated individuals in order to increase the number of existing populations.

This paper is a summary of the historic and current knowledge of the occurrence of lake minnow, Eupallasella percnurus (Pall.) in Pomorskie Voivodeship in Poland. It considers factors threatening the existence of this species, and determines possibilities for the conservation and protection of sites which it inhabits. Currently, E. percnurus is known to inhabit 102 sites in the voivodeship, which constitutes 59.3% of all known sites in Poland (172). The main threats to E. percnurus sites and/or populations in Pomorskie Voivodeship include the draining and drying up of water bodies and their transformation for recreational use. Currently, only 10 of the sites are classified as threatened to a low level, while 44 sites are endangered to a high level. Almost half of all the sites (45) are subject to protection within the framework of the European Ecological Natura 2000 Network, and these probably have the greatest chance of survival.

In July and August 2010, the Lincoln-Petersen capture-recapture method was used to assess the size and basic structure of a newly established population of the endangered in Poland cyprinid fish lake minnow, Eupallasella percnurus (Pall). The population that inhabits a small (0.08 ha) peat excavation site in the village of Kowalicha near Radzymin (Mazowieckie Voivodeship, Poland) was initiated in 2004-2006 using the translocations of a total of 1530 cultivated individuals, mostly juveniles aged 0+. The total size of the E. percnurus population was estimated to be 600 individuals excluding aged 0+. The population size is not considered to be large in comparison with other populations inhabiting water bodies of similar surface areas. Males proved to be predominated by females – phenomenon typical of populations of this species – but at relatively high ratio of approximately 1:4. Most of females were aged 2+, whereas most of males were older (3+). These data indicate that the population remains in the early stages of development. The Lincoln-Petersen method proved useful in the studies of the size and structure of E. percnurus populations.

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In Poland, lake minnow (Eupallasella percnurus Pall.) inhabit 160 sites, including 44 in the eastern part of the country. Their habitats are mainly small and shallow peat holes vulnerable to complete destruction due to being dried or overgrown. Such processes are regularly observed, with ~ 60% of sites having vanished since the 1950s. Therefore, this species is one of the most endangered fish species from the Cyprinidae family in Polish inland waters. A GIS approach was adopted to fully analyze their habitat loss. The habitat area was marked in four time periods (from the 1960s to 2018) in reference to 26 sites composed of 111 reservoirs and representing almost 60% of all those documented in Eastern Poland. On this basis, the rate at which the habitat will vanish and the predicted time when this will happen were calculated. The results showed that the mean vanishing rate oscillates between 1 and 2% of the area per year for 50% of the analyzed sites (N = 13). For three sites (11%), this value does not exceed 1% of each area per year and is higher than 2% for the rest of the sites (39%). The results indicate that if the process of overgrowing and shallowing is not stopped, 58% of the analyzed sites will disappear in the next 50 years (including 8 (31%) in the next 20 years). This trend may lead to a serious decline in the species population or even its extinction in the next decades. Passive protection has proven to be insufficient in preserving lake minnow habitats. Therefore, there is an urgent need to undertake decisive protection action, as proposed in this manuscript.

Habitat degradation and loss as key drivers of regional population extinction

[This corrects the article DOI: 10.1371/journal.pone.0168191.].

The lake minnow (Eupallasella percnurus) is critically endangered. In this paper we characterize the genetic properties of this fish over its range of occurrence in Poland and propose the use of this knowledge in its active protection. Twelve populations of lake minnow from across its range in Poland were investigated. 13 microsatellite loci were investigated to evaluate genetic variation and distance among populations. The magnitude of the genetic bottleneck or founder effects was investigated. In the studied populations, the allelic diversity and heterozygosity showed that genetic variation in this species is low. At most loci, only 2–3 alleles per population were detected. The average number of alleles detected across all loci was 35, and ranged from 24 to 53. The average observed heterozygosity (Ho) across all investigated loci was 0.38 (range 0.21–0.59); the average expected heterozygosity (He) was 0.36 (range 0.18–0.55). The populations remained in Hardy-Weinberg equilibrium. The average Garza-Williamson M index value for all populations was low (0.47), suggesting a reduction in genetic variation due to a founder effect or a genetic bottleneck. Genetic distance among populations was high or very high (FST range: 0.20–0.64; δμ2 range: 1.32–16.98); this was likely a consequence of low gene flow among isolated populations, a founder effect or other genetic bottleneck, and strong genetic drift. The large genetic differences among the investigated lake minnow populations are likely to also exist among other populations of this species, and knowledge of these differences should inform active protection programs based on translocation of wild or cultivated fish of this species. The method presented here can potentially be applied to any population of lake minnows or closely related species.

Assessment of extinction risk may depend not only upon the current state of the landscape and its projected trajectory of change, but also on its past disturbance history. We employed a spatially structured demographic model to evaluate extinction risk for several generic migratory songbirds within landscapes subjected to ongoing habitat loss and fragmentation. We generated different scenarios of dynamic landscape change using neutral landscape models, in which breeding habitat was systematically destroyed at various rates (0.5%, 1%, or 5% per year) and degrees of fragmentation, thus enabling us to determine the relative contribution of these factors to population declines. Extinction risk was assessed relative to thevulnerability threshold,the point where the change in population growth rate (Δλ) scaled to the rate of habitat loss (Δh) falls below −1% (Δλ/Δh= −0.01). Our model predicts that songbirds are likely to exhibit lagged responses to habitat loss in landscapes undergoing rapid change (5% per year). In such scenarios, the landscape changed more rapidly than the demographic response time of the population, such that population growth rates never exceeded the vulnerability threshold, even though these species inevitably went extinct. Thus, songbirds in landscapes undergoing rapid change might not be assessed as “at risk” until the population's demographic potential has been seriously eroded, which would obviously compromise the success of management actions aimed at recovering the population. Furthermore, our model illustrates how assessment of a species' extinction risk may vary widely among landscapes of similar structure, depending upon how quickly the landscape achieved its current state. Thus, information on the current landscape state (e.g., amount of habitat or degree of fragmentation) may not be sufficient for assessing long‐term population viability and extinction risk in the absence of information on the history of landscape disturbance.

In the presented study, data on the size and structure of cattle herds in Wielkopolskie, Podlaskie, and Mazowieckie voivodeships in 2019 were analyzed and subjected to modelling with the use of artificial intelligence, namely artificial neural networks (ANNs). The potential amount of biogas (m3) from cattle manure and slurry for the analyzed provinces was as follows: for the Mazowieckie Voivodeship, 800,654,186 m3; for the Podlaskie voivodeship, 662,655,274 m3; and for the Wielkopolskie voivodeship, 657,571,373 m3. Neural modelling was applied to find the relationship between the structure of the herds and the amount of generated slurry and manure (biomethane potential), as well as to indicate the most important animal types participating in biogas production. In each of the analyzed cases, the three-layer MLP perceptron with a single hidden layer proved to be the most optimal network structure. Sensitivity analysis of the generated models concerning herd structure showed a significant contribution of dairy cows to the methanogenic potential for both slurry and manure. The amount of slurry produced in the Mazowieckie and Wielkopolskie voivodeships was influenced in turn by heifers (both 6-12 and 12-18 months old) and bulls 12-24 months old, and in the Podlaskie voivodeship by calves and heifers 6-12 months old. As for manure, in addition to cows, bulls 12-24 months old and heifers 12-18 represented the main factor for Mazowieckie and Wielkopolskie voivodeships, and heifers (both 6-12 and 12-18 months old) for Podlaskie voivodeship.

In the economy of the 21st century one of the most important resources and factors determining the strengths and competitiveness of regions is human capital. This role in regional development has been noticed in the policy of the European Union. The article presents the results of research into the diversity of human capital in Poland. The category was determined using fifteen indicators, and their selection was dictated by the availability of data across voivodships and their comparability over time. The aim was to verify the diversity of the human capital of voivodships in Poland within the regional structure of the country. The research included an attempt to measure and take into account changes in their diversity in dynamic terms (2007–2018). The research tool was factor analysis. The results allowed the assessment and observation of differences in the classification of voivodship groups. The schooling coefficients of individual types of schools have an impact on the grouping and diversity of similar voivodships in terms of human capital. Demographic processes are particularly unfavorable in the Świętokrzyskie voivodeship. The dynamic approach allows us to claim that groups of objects are characterized by a different specificity. The most favorable quality of human capital was assessed in the Mazowieckie voivodeship. It was observed that the voivodships in Poland also differentiate the indicators characterizing the working and post-working age population. The goal is characterized by variability in time. Given the dynamic dimensions of the category, achieving them in a different way seems very important.

Analysing the persistence and viability of small populations is a key issue in extinction theory and population viability analysis. However, there is still no consensus on how to quantify persistence and viability. We present an approach to evaluate any simulation model concerned with extinction. The approach is devised from general Markov models of stochastic population dynamics. From these models, we distil insights into the general mathematical structure of the risk of extinction by time t, P0(t). From this mathematical structure, we devise a simple but effective protocol – the ln(1−P0)‐plot – which is applicable for situations including environmental noise or catastrophes. This plot delivers two quantities which are fundamental to the assessment of persistence and viability: the intrinsic mean time to extinction, Tm, and the probability c1of the population reaching the established phase. The established phase is characterized by typical fluctuations of the population's state variable which can be described by quasi‐stationary probability distributions. The risk of extinction in the established phase is constant and given by 1/Tm. We show that Tmis the basic currency for the assessment of persistence and viability because Tmis independent of initial conditions and allows the risk of extinction to be calculated for any time horizon. For situations where initial conditions are important, additionally c1has to be considered.

The El Rincon stream frog (Pleurodema somuncurense) is a microendemic species currently restricted to the thermal headwaters of the Valcheta Stream in the Somuncura Plateau, Northern Patagonia, Argentina. This species is listed as Critically Endangered on the IUCN Red List. The critical status of the El Rincon stream frog requires urgent management actions. Population viability analysis is one of the most effective tools to predict extinction risk and assess the potential effect of management actions. It is also helpful in knowing the minimum viable population (MVP) and minimum area requirements (MAR). However, this tool is rarely used to model viability in endangered amphibians. This work aimed to: (i) estimate the extinction risk of each local population of El Rincon stream frogs; (ii) estimate the MVP and MAR; and (iii) model reintroduction and supplementation of the population as management strategies for this species. Practical management actions are also suggested for each relict population. Population viability analyses were developed in Vortex 10.3.5.0 to estimate each local population's extinction risk, MVP and MAR. Supplementation and reinforcement of individuals were also modelled for local populations that are below the MVP. The estimated MVP was 430 individuals, while MAR reached 683 m2. Modelling of reintroducing individuals showed that a single reintroduction of at least 50 adults, 140 juveniles, or 1,000 tadpoles would be needed to achieve a viable population. Local populations below the MVP would benefit from supplementation of a pair of adult frogs every 17 to 20 years. This study provides a fundamental basis for assessing and improving current management and planning future conservation strategies within the framework of the El Rincon stream frog action plan.