Trophic Pyramid Research Articles

Microbial Mats in the Terraforming of Mars

Microbial mats including cyanobacteria, and in particular desert cyanobacteria, probably genetically engineered to improve some of their capabilities, may play a crucial role in the terraforming of Mars, as part of wider ecosystems and providing a range of ecological services including but not restricted to the production of oxygen, encompassing also the production of greenhouse gases, the creation and fixing of soil, dust amelioration, providing the foundation of trophic pyramids, and psychological benefits to settlers from gardening and landscape variation. Cyanobacteria have evolved on Earth, where they prompted the GOE (Great Oxidation Event), to survive and thrive facing some of the key environmental challenges awaiting them in the Red Planet, including high levels of ultraviolet radiation and radical temperature shifts. Present-day Mars resembles pre-GOE Earth on many counts. To date, some key experiments have already established the resilience of cyanobacteria such as Nostoc sp. to Mars-like conditions, and this has been supplemented by theoretical models and studies involving other species such as Chroococcidiopsis. However, much more research is needed before we can state beyond any reasonable doubt that these promising characteristics can be translated into practice. Future research should focus on ecosystems, not single species, and experiments should gradually move to ideally reflect actual real conditions, including the presence of mutually supportive microorganisms, extracellular substances (such as EPS, extracellular polymeric substances), and mineral grains, sand, or cobbles, as are sometimes found in terrestrial deserts, until, finally, viable microbial mats are tested in Mars-like conditions. Keywords: Terraforming, Mars, Cyanobacteria, Microbial mats, Biofilms, Ecosystems

The role of evolutionary processes in determining trophic structure

There are two contrasting hypotheses regarding the drivers of biomass‐distribution among trophic levels within ecosystems. Energetic or bottom–up models propose control by supply of energy, either from autotrophy or from the underlying trophic level. Dynamical or top–down models propose control by predators in the overlying trophic level. Although multiple approaches have been used to reconcile these hypotheses, they have rarely considered the evolutionary pressures created by different distributions of biomass. Here, we study the effects of these evolutionary processes using an agent‐based, spatially‐explicit, eco‐evolutionary model. We demonstrate that, when ecosystems are simple and predator–prey relationships between species are fixed and do not evolve, primary productivity limits the number of trophic levels. In this case, the abundance in the top trophic level is always limited by productivity. However, productivity‐limited trophic levels subject those below them to limitation by predation, and predation‐limited trophic levels allow trophic levels below them to grow until limited by productivity. These results match the expectations of the exploitation ecosystems hypothesis (EEH), which predicts the same pattern of alternating top–down and bottom–up control on trophic levels. When species are able to evolve to adaptively adjust their trophic levels, however, selection is liable to lead to collapse of the trophic pyramid through prey switching. Under these conditions, all trophic levels experience bottom–up control. When the evolution of prey switching is restricted, higher trophic levels are evolutionarily stable and the predictions of the EEH are once again met; the stability of long food chains is thus dependent on the difficulty associated with prey switching. These results suggest that, at least under the combinations of model parameters explored in this study, evolutionary limitation is key to maintaining trophic structure.

A scalable and normalized reef status index for assessing fish trophic structure reveals conservation gaps

The trophic structure of ecosystems, reflecting biomass distribution across different levels, is paramount for understanding energy dynamics and community assemblages in marine environments. Typically, ecosystems devoid of external energy influx exhibit a bottom-heavy trophic pyramid, yet higher biomass systems often display a top heavy or concave distribution. Such structures are susceptible to alterations due to species turnover, trophic cascades, and anthropogenic impacts, particularly the phenomenon of ’Fishing down’ the food web. Recognizing the trophic structure as a simplified yet potent indicator, we identify the necessity for a standardized, expedient method to assess reef health—a criterion fulfilled by our Normalized Reef Status Index (NRSI). The NRSI offers a novel metric for scientists and conservation practitioners to augment traditional reef health assessments. Utilizing the NRSI, we assessed the ecological status of 346 reefs across the Mexican Pacific. Our results demonstrated that only reefs within Fully Protected areas conform to the concave trophic structure indicative of low human interference. In stark contrast, unprotected reefs exhibited a depleted trophic architecture, often devoid of apex predators. This depletion not only threatens coastal livelihoods and food security but also disrupts the delicate balance of marine ecosystems critical to sustaining global ecological functions. Through the NRSI, we provide a robust, scalable tool for ongoing monitoring and conservation efforts, underscoring the urgent need to address human-induced trophic disruptions.

Hysteretic and asynchronous regime shifts of bacterial and micro-eukaryotic communities driven by nutrient loading

Nutrient pollution is pervasive in many urban rivers, while restoration measures that reduce nutrient loading but fail to improve biological communities often lack effectiveness due to the indispensable role of biota, especially multi-taxa, in enhancing ecosystem stability and function. The investigation of the response patterns of multi-taxa to the nutrient loading in urban rivers is important for the recovery of biota structure and thus ecosystem function. However, little is known about the response patterns of multi-taxa and their impact on ecosystem structure and function in urban rivers. Here, the study, from the perspective of alternative stable states theory, showed the hysteretic response of both bacterial and micro-eukaryotic communities to nutrient loading based on the field investigation and environmental DNA metabarcoding. Bistability was shown to exist in both bacterial and micro-eukaryotic communities, demonstrating that the response of microbiota to nutrient loading was a regime shifts with hysteresis. Potential analysis then indicated that the increased nutrient loading drove regime shifts in the bacterial community and the micro-eukaryotic community towards a state dominated by anaerobic bacteria and benthic Bacillariophyta, respectively. High nutrient loading was found to reduce the relative abundance of metazoan, but increase that of eukaryotic algae, which made the trophic pyramid top-lighter and bottom-heavier, probably exacerbating the degradation of ecosystem function. It should be noted that, in response to the reduced nutrient loading, the recovery threshold of micro-eukaryotic communities (nutrient loading = ∼0.5) was lower than that of bacterial communities (nutrient loading = ∼1.2), demonstrating longer hysteresis of micro-eukaryotic communities. In addition, the markedly positive correlation between the status of microbial communities and N-related enzyme activities suggested the recovery of microbial communities probably will benefit the improvement of N-cycling functionality. The obtained results provide a deep insight into the collapse and recovery trajectories of multi-trophic microbiota to the nutrient loading gradient and their impact on the N transformation potential, therefore benefiting the restoration and management of urban rivers.

Relationships between pesticides, polychlorinated biphenyls, blood parameters and oxidative stress of white stork Ciconia ciconia chicks in Poland

The white stork Ciconia ciconia is a bird species located at the top of the trophic pyramid in grassland and wetland ecosystems. This charismatic species is susceptible to pesticides and their environmental residues. In 2016, we collected blood samples from 114 white stork chicks across Western and Southern Poland. Chicks were sexed by molecular analysis and aged by development pattern. We studied the relationship between the concentration of pesticides (beta-HCH, heptachlor, aldrin, endrin, 4.4′-DDD, 4.4′-DDE and 4.4′-DDT) and of PCB in the chicks’ blood with blood morphology and biochemistry parameters in the blood. The mean (± SD) values of concentrations of above detection level pesticides were: for (1) beta-HCH 4.139 ± 19.205; (2) 4.4′-DDE 9.254 ± 91.491 and additionally (3) PCB 16.135 ± 44.777 ppb. We found negative relationships between beta-HCH and oxidative stress enzyme activity in the blood, between beta-HCH and leukocyte concentration and between 4.4′-DDE and catalase activity. We also found a positive relationship between the concentration of pesticides in blood and the age of chicks. Interestingly, we found a higher concentration of PCB in the blood of male stork chicks than in female stork chicks. We provide more evidence that the presence of pesticides in the environment can be a strong stress factor, shaping the health status of birds.

ФРАКЦИОНИРОВАНИЕ ПЛАНКТОНА С ПОМОЩЬЮ ПОСЛЕДОВАТЕЛЬНОЙ ФИЛЬТРАЦИИ И ПОСТРОЕНИЕ ПИРАМИД БИОРАЗНООБРАЗИЯ

Lotka-Volterra predator-prey models are used to study community ecology, but their ability to generate ecological pyramids compared to field data has not been investigated in detail. In this paper, agent-based modeling (ABM) was used instead of systems of ordinary differential equations (ODE). It was shown that the two-component producer-consumer system is unstable, whereas the three-component system with consumers of the 1st and 2nd order is stable under prolonged simulation. Time slices as the program progresses can generate both ecological pyramids and cascades. Simulation results are consistent with experiments on separation of the Black Sea plankton from the area of Cape Fiolent (Crimea) into fractions ranging in size from 2 mm to 2 microns. Although biodiversity in individual samples at different points in time as well as abundance vary widely, both predictably decline with rising trophic levels in cases where the number of tests increases over time.

Africa's overlooked top predator: Towards a better understanding of martial eagle feeding ecology in the Maasai Mara, Kenya

Raptors exert top‐down influences on ecosystems via their effects on prey population dynamics and community composition. Most raptors are sympatric with other predators, thus complicating our understanding of their relative influence in these systems. Estimates of kill rates and prey biomass recycling have been used as predation metrics that allow quantitative comparison among species and assessment of the relative role of single species within complex food webs. Few studies have produced findings of kill rates or prey biomass recycling for raptors. We used a supervised machine learning algorithm to behaviourally classify high resolution accelerometer informed GPS locations of tagged adult non‐breeding martial eagles Polemaetus bellicosus in the Maasai Mara region of Kenya to estimate kill rates and prey biomass recycling. Eagle locations classified as feeding were clustered using distance and time thresholds to identify kills and calculate kill rates. Identified kill sites were quickly ground‐truthed to confirm kills and identify prey species. We estimated kill rates for martial eagles at 0.59 kills day‐1 for males and 0.38 kills day‐1 for females, and we estimated biomass recycling per ground‐truthed kill at 1796 g for males and 3860 g for females. From our sample of identified ground‐truthed kills, ‘gamebirds' was the most frequently recorded prey category for male eagles and ‘small ungulates' was the most frequently recorded prey category for female eagles. These results position martial eagles close to sympatric mammalian top predators in trophic pyramids and provide evidence for their classification as a top predator.

Ecosystem dynamics and hypoxia control in the East China Sea: A bottom-up and top-down perspective

Decades of overfishing have greatly altered the community structure in the East China Sea (ECS). The decrease of top predators in the food web has weakened the control exerted from higher trophic levels. As a result, the biomass of benthic crustaceans, representing the third trophic level, has increased. This has probably led to a restriction of the second trophic level, diminishing its ability to control primary producer biomass. Consequently, the ecological pyramid of trophic levels in the ECS has been altered, reducing the top-down control on the first trophic level. This has made algal blooms more susceptible to occur under nutrient loads, temperate temperatures, and light availability. The reduced abundance of the fourth trophic levels has caused a larger portion of primary productivity to sink directly to the benthic community, bypassing the food web. This influx of sinking organic matter has resulted in organic enrichment in the bottom waters, impacting the biomass and diversity of benthic organisms. Furthermore, it has intensified anthropogenic carbon storage in the sediment. Subsequently, intense decomposition processes occur, leading to the development of anoxia and even hypoxia. The seasonal hypoxia off the Changjiang Estuary can be attributed to the combined influence of top-down control and bottom-up control related to nutrient loading, and terrestrial inputs. In order to mitigate extreme hypoxia events, it is necessary to implement comprehensive fisheries policies that prioritize the maintenance of a healthy and functional ecosystem. This approach should go beyond relying solely on watershed management strategies to regulate riverine inputs. Plain language summaryDecades of overfishing changed the food web in the East China Sea and weaken the resistance of ecosystem to hypoxia. Commercial fishing on top predators decreases the fourth trophic level while relatively increases the third trophic represented by crab and shrimp, which enhances grazing on the zooplankton. The decrease of the second trophic level fails to control the biomass of phytoplankton, thus more primary productivities directly sink to the benthic community and cause organic enrichment. The elevated flux of organic matters to the bottom waters causes the thrive of the carbs and shrimps, as well as more remineralization processes and eventually low oxygen level. Unlike the bottom-up perspective of hypoxia mechanism off the Changjiang Estuary, which is from the nutrient load, phytoplankton bloom, quick sink, effective decomposition and eventually hypoxia, the top-down control focuses on the changes of ecosystem structure and thus derived hindered energy transfer, changed community structure, enhanced carbon sink, elevated remineralization and ultimately hypoxia. These two mechanisms combine with each other and control the seasonal hypoxia off the Changjiang Estuary and even other coastal regions around the world.

Need Assessment for Developing Learning Modules Based on Discovery Learning Ecosystem Materials

The scientific approach is a form of character education integrated into learning activities. The success of implementing character values internalization learning is largely determined by the teacher's skills in selecting and implementing appropriate learning models. However, in reality, school teachers still do not apply learning models that suit the students' character, and the teaching materials used also do not support character internalization learning. So, this research aims to determine the characteristics of students and the type of materials and modules to be developed based on conditions in the field. This research uses qualitative research with a descriptive approach based on ongoing problems in class X SMA Bina Ilmi, Palembang City—techniques for obtaining data in the field, namely interview techniques, observation, and documentation. The research results showed that students were of an age that had entered the formal operational stage, understood abstract concepts, had high curiosity, and tended to like discovering new things. Meanwhile, the material analysis results showed three ecosystem materials that can stimulate students' curiosity: interactions between species, ecosystem components, and ecological pyramids. This material will be made into a teaching module based on discovery learning. This model-based module can make students build their knowledge through independent observation to increase students' reasoning power in developing environmental concepts following ecosystem material and learning resources that can provide interesting discovery concepts to explore curiosity to observe and process information in the learning process and understand ecosystem material.

Evaluation of the effectiveness of innovative methods in biology teaching

The goal of our research work is to study the effectiveness of innovative methods of teaching biology. It is difficult to keep the attention of modern students in one direction, because social networks, society, and the development of time are affecting it. Innovative teaching methods increase the student's activity, help in understanding biological terms, their content, memorizing them and increasing their ability to use them in practice. To test the effectiveness of the innovative method, we decided to compare it with the traditional method. We used the following types of innovative methods: technological integration, project-based learning, gamification, experience-based learning, differentiated learning, video and audio lessons, mobile applications. We trained Group B with these methods for 2 weeks, while Group A was taught only with traditional methods. In the traditional method, we lectured only on the topic, students explained what they understood and answered the question. When we taught Group B, we used a combination of innovative methods. For example, audio and video lessons, as well as gamification, were used to explain a lesson on “Ecological Pyramids.” And for tasks related to the topic, mobile applications and project-based learning were used. In the topic “Study of the consistency of ecosystems in your region with the illumination of statistical methods of analysis” the method of learning based on experience was used.

Energy, Trophic Dynamics and Ecological Discounting

Ecosystems provide humanity with a wide variety and high economic value-added services, from biomass structuring to genetic information, pollutants’ decomposition, water purification and climate regulation. The foundation of ecosystem services is the Eltonian Pyramid, where via prey–predator relationships, energy metabolism and biomass building take place. In the context of existing ecosystem services classification and valuation methods (e.g., CICES, MEA, TEEB), financial investments in ecosystem services essentially address the conservation of trophic pyramids. Our work’s main target is to investigate how trophic pyramids’ dynamics (stability or instability) impact the long-run discounting of financial investments on ecosystem services’ value. Specifically, a trophic pyramid with highly fluctuating populations generates higher risks for the production of ecosystem services, hence for ecological finance instruments coupled to them, due to higher temporal uncertainty or information entropy that should be incorporated into their discount rates. As this uncertainty affects negatively the net present value (NPV) of financial capital on ecosystem services, we argue that the minimization of biomass fluctuations in trophic pyramids via population control should be among the priorities of ecosystem management practices. To substantiate our hypothesis, we construct a logistic predation model, which is consistent with the Eltonian Pyramid’s ecological energetics. As the logistic predator model’s parameters determine the tropic pyramid’s dynamics and uncertainty, we develop an adjusted Shannon entropy index (H(N)ADJ) to measure this effect as part of the discount rate. Indicatively, we perform a Monte Carlo simulation of a pyramid with intrinsic growth parameter values that yield oscillating population sizes. Finally, we discuss, from an ecological energetics standpoint, issues of competition and diversity in trophic pyramids, as special dimensions and extensions of our analytical framework.

The natural food base of the ponds in Noginsky district of Moscow region

The purpose of this work was to study the natural food base of the ponds in the Noginsk district of the Moscow region in October-November 2022. The selection of hydrobiological materials was carried out in October-November 2022. The pond №1 is a main pond of the EPB of RRIFF, a branch of the FSBSI FRC RIAH named after L.K. Ernst, with an area of 4,48 ha, fertilized with goose and duck droppings. Pond № 2 is ownerless, with peat soil, with an area of about 21,27 hectares. From a fishery point of view, the state of phytoplankton turned out to be more favorable in the ownerless pond. The biomass of phytoplankton in this pond is higher, it is formed mainly by green algae, consumed by both juvenile fish and planktonic organisms, through which the primary production is transferred to the higher levels of trophic pyramid. In the pond № 1, the biomass is much lower and in many respects formed by low-edible blue-green algae. The species diversity of the zooplankton in the EPB RRIFF pond, fertilized with waterfowl droppings, is significantly higher than in the big ownerless pond. The zooplankton biomass here is more than 2 times higher. The number of zooplankton is 1,34 times higher. The percentage of oligochaetes in the benthic invertebrate communities samples from the pond № 1 (68%) indicates moderate water pollution in October-November 2022 with organic matter. Thus, the head pond of the EPB RRIFF, fertilized with waterfowl droppings (the integrated technologies), demonstrated for the benthic invertebrate communities the best indicators of the natural food base state, both in general and in terms of indicators of the individual taxons. The components of the natural food base, which are crucial for the fish nutrition: phytoplankton and benthic invertebrate communities, turned out to be higher in October-November 2022 in the EPB RRIFF pond, fertilized with waterfowl droppings. However, the indicators of phytoplankton were better in the ownerless pond of the Noginsk district of the Moscow region. One of the reasons for the less favorable state of phytoplankton in the EPB RRIFF pond may be the eating of green algae by zooplankton.

Assessment of the bioresource potential of Kazan city’s lake ecosystems by phytoplankton indicators

Nowadays protection and sustainable management of biological resources is of particular importance. The most important area of hydrobiological research is the assessment of the bioresource potential of aquatic ecosystems (Alimov et al., 2005). Phytoplankton is the basis of life and the most important component of the bioresource base in the aquatic ecosystem. Phytoplankton indicators (primarily abundance and biomass) are widely used to assess the bioresource potential of lakes due to its position as an autotrophic producer at the base of the ecological pyramid of the lake ecosystem (Bulion, 2005, 2019; Alimov, 1989, 2000; Alimov et al., 2005). Our study is aimed to research phytoplankton indicators to assess the bioresource potential of Kazan city’s lake ecosystems (Volga region, Russia).

Биогеохимический мониторинг содержания химических элементов Каспийского моря

The aim of the research was to conduct biogeochemical monitoring of heavy metals composition in the ecosystem of the northwestern part of the Caspian Sea. The objects of the research were the water of the northwestern part of the Caspian Sea, bottom sediments, different types of crustaceans, mollusks, fish, as well as the Caspian seal. As a result of the research, metal concentrating aquatic organisms in the Caspian Sea were identified. Thus, gammarus accumulates Zn, shrimp – Cu, crab – Pb and Ni, balanus – Hg, Pb, Cd; mollusk Didacna accumulates mainly Zn, Cd, and Hg; mytilaster – Cu, Co; cerastoderma – Pb; vobla – Zn and Hg; benthophilus - Pb and Mn; needlefish – Cu, Pb, Cd, and sprat – Zn and Hg. Specific features of metal accumulation by hydrobionts have been found out: Zn, Pb and Cd are accumulated mainly by invertebrates; Cu, Co, Mn are accumulated to the greatest extent by representatives of Crustacea; Ni – by Mollusca species; Hg is accumulated to the greatest extent by vertebrates. There have been revealed the regularities in distribution of chemical elements concentrations in the organs and tissues of aquatic organisms occupying the tops of the trophic pyramids: Zn, Cu, Hg are predominantly accumulated in the liver, Co, Ni, Zn, Pb and Cd are accumulated in the kidneys, Pb, Co, Mn are accumulated in the gills, Hg – in muscle tissues. In Phoca caspica Pb accumulates in the adipose tissue and lungs, Hg, Cu, Zn, Mn, Cr, and Co – in the liver, and Pb, Cd and Ni – in the kidneys. Taking into account the calculated coefficients of chemical elements accumulation, it was inferred that Hg and Zn can accumulate in almost all links of the trophic chain; Cu, Co, Ni, Cd, Pb are accumulated mainly by invertebrates; Cr and Mn accumulate to a greater extent in bottom sediments.

Незвіданий облік породільних барлогів ведмедя білого (Ursus maritimus) на островах Врангеля та Геральда у 1982 році

In March–May 1982, a local expedition worked in the Arctic, in the east of Wrangel Island (WI) and Herald Island (HI), to carry out a survey of polar bear dens. The results of that expedition have not been published. The author has found a copy manuscript of the expedition diary and has highlighted the key results. For two months, five ex-plorers had been surveying the area and found 139 dens and sighted 57 bears (♀ad + juv). The average number of offspring (ANO) was 1.43 on WI and 1.86 on HI. The number of successful offspring on WI usually was one or two cubs, or even three on HI. Based on the available sample (n=44) it was shown that when taking into account the survey data of cub traces in calculations of ANO (on WI), the obtained results do not differ notable. The time that lasted from the date of the opening of the den to the date of the final leave of the den by females (with or without the young) was 4 to 14 days, but most often 6 days. The highest frequency of den opening was noted on 27–28 March. Four cases of death of cubs, including a newborn, were recorded. The fate of 43 dens was monitored and measurements of 11 dens were taken. Two unusual dens were found: one with a very complex corridor and another one with a 4.5 m long vertical tunnel. Simplified 3D models of dens were given in the article for the first time proving that linear measurements practiced by researchers give a primitive picture of the den structure. After leaving the maternity den, the female can build temporary, simple shelter for herself and the young. During 1964–2020, dens were found on these islands only on the ground, and in 1980 the author found several dens on the sea, among ridges of pressured ice. The article is amended by the author’s estimations regarding the place of the polar bear in ecologi-cal pyramid of those islands. Recommendations are given for the improvement of polar bear survey techniques. The publication of a Ukrainian language article on the biology of U. maritimus is rare for the school of Ukrainian mammalogists and is of clear enlightening importance for scientists, lecturers, students, Wikipedia editors, and oth-ers, as well as a contribution of the author to the Ukrainian body of literature on the animal world of the Arctic.

ЭКСПРЕСС-ОЦЕНКА РАЗМЕРНЫХ ФРАКЦИЙ ПЛАНКТОНА В АКВАТОРИИ Г. СЕВАСТОПОЛЬ ЗИМОЙ 2021-2022 ГГ: МОДЕЛЬНЫЕ ИССЛЕДОВАНИЯ

For the purpose of monitoring the water area of Sevastopol a line of devices for plankton macrofiltration in the size range from 2 mm to 2 microns has been developed. Twelve stations have been chosen from Inkerman to Fiolent with total length of 30 km. From piers far out at sea, 50-500 liters of seawater were sampled from the surface and filtered through a system of successive sieves 2 mm, 300, 150, 84 microns and a 2 μm fiber filter. In the winter of 2021-2022, when the seawater temperature was 8 °C, the diversity of plankton morphotypes was low. For all stations, the number of morphotypes increased as the size fraction decreased in the form of ecological pyramids. It was found that the richness of morphotypes in Inkerman is significantly lower than at other stations. Samples from neighboring stations may differ in the composition of morphotypes up to 50% (spatial section). Also, sea water samples taken at the same station with an interval of 1.5 months differed by 50% in the composition of morphotypes (time slice). The obtained results indicate that the developed technique of sequential filtration gives a visual representation of the state of meso-, micro- and nano-plankton in seawater samples.

Microfossils in bottom-hydrothermal sediments of the Saf'yanovskoe Cu-Zn deposit (Middle Urals)

Research subject. Framboidal pyrites and sulfide micro-concretions in carbonaceous-siliceous and ore rocks of the Safyanovskoye deposit (Middle Urals). Aim. To identify the signs of vital activity of microbial communities in bottomhydrothermal deposits using the example of the Safyanovskoye sulfide deposit. The methods. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Results. TThe analyzed ore and carbonaceous-siliceous rock samples showed the presence of mineralized silicon dioxide films covering framboidal pyrites. Micro-concretions were found to consist of microfossils of filamentous organisms and framboids. Pyrite samples included the remains of tubular casts of sulfidized vestimentifera and polychaetes, associated with framboids. The possibility of using fossilized remains of microbial communities for distinguishing bottom-hydrothermal facies among pyrite deposits was confirmed. Conclusions. Hydrothermal-sedimentary deposits are characterized by the traces of specific microbial communities, since prokaryotic organisms were pioneers in hydrothermal oases. Their long active existence created a basis for the second trophic link, i.e. filter feeding macrofauna and endosymbiotrophs. These organisms, in turn, formed another level in the food chain of the trophic pyramid. It is believed that micro-concretions and framboidal pyrites are indicators of the vital activity of microbial communities.

A green approach to arsenic removal using ZnO nanoparticles synthesized from Acacia Catechu leaf extract

One of the world's most prevalent environmental challenges is heavy metal contamination in water. Because of uncontrolled discharge from numerous sectors, this issue is particularly dangerous in rising countries' large cities. Because of their carcinogenic effects on humans and harmful environmental effects, heavy metals are expected to require special attention. Heavy metals can enter the environment from both anthropogenic and natural sources. As a result, bioaccumulation and transmission to the ecological pyramid via the food chain are very likely. Heavy metal removal is a difficult issue that must be solved if harmful effects on individuals and the environment are to be avoided or mitigated. The current study focuses on using the Acacia Catechu tree to make zinc oxide nanoparticles in an environmentally friendly manner. The Acacia Catechu plant's leaves were chosen because they contain a substantial amount of Flavonoids and Phenols, which are principally responsible for decreasing the precursor without the need of conventional synthesis chemicals. The nanoparticles were characterised by UV–Vis Spectroscopy, XRD, FT-IR, SEM, DLS, and TEM imaging methods. When perfect conditions are maintained at a dose of 0.3 gm, pH of 7, and an optimum period of 40 min, the highest percentage removal of arsenic utilising ZnO nanoparticles is 90.3 percent.

The Value of Protected Areas Ranger Service Personnel for Biodiversity Monitoring: Case Study in Paklenica National Park (Croatia)

Abstract To preserve the long-term survival of habitats and wildlife, it is necessary to monitor their status. In protected areas, that is, biodiversity centres, rangers have excellent knowledge of specific locations and they spend a large amount of time in the field. But since rangers are not required to have a university degree, the question is whether they can be an added value in baseline survey monitoring. To investigate this issue, a case study was conducted in the Paklenica National Park (Paklenica NP), Croatia, using camera trapping survey between 2011 and 2016 at 22 camera sites. The aims of this survey were (1) to collect baseline data of mammalian diversity, (2) to analyse the regulatory effect of top predators on the trophic pyramid through top–down effects and (3) to estimate the data gathered by ranger service from the Paklenica NP. Data gathered through this study represents the first peer-reviewed list of medium- to large-sized mammals for Paklenica NP, as up till now, there is no peer-reviewed published paper of Paklenica NP mammalian diversity. Results showed that the recorded top predator–mesopredator–prey ratios were concordant with the trophic pyramid hypothesis. Also, as it was expected according to the literature, species richness indices were higher when top predators were present. On analysing the costs for conducting camera trapping survey by external and internal services, a significant difference was observed. Internal rangers’ cost was nine times lower than the external service cost. Future research run by rangers needs to be conducted in way to capture all mammalian biodiversity. Therefore, we propose camera trapping methodology for rangers in the protected areas since this may be an invaluable tool for biodiversity monitoring.

Трофический потенциал интегрированных систем на основе индустриальной аквакультуры

Recirculating aquaculture, using closed water supply installations, has become increasingly important in recent decades as a most promising technology for integrating the production of fish farming and crop production. One of the most characteristic examples of combining two industrial technologies is aquaponics. This artificial biological system (IBS) allows the two subsystems included in it, fish farming and crop production to complement each other. Food not consumed by fish and excrement are a nutrient medium for plants, which in turn purify the habitat from substances harmful to fish, which is especially important in conditions of water recycling. In order to determine the quantitative and qualitative potential of the forage base of organisms on the second link of the trophic chain of IBS created on the basis of aquaculture in a closed water supply installation, an experiment was conducted, the results of which helped to determine the composition and number of organisms promising for inclusion in the technological regime of further joint cultivation. Methods and devices have been developed to remove from the fish-water tank the undissolved sediment formed during the cultivation of fish for the purpose of studying it, the results of the experiment have been analyzed and formalized, a method for converting the resulting ichthyogenic sediment into the feed potential of more complex IBS has been proposed. The results of a quantitative study of the sediment indicate that more than 15% of the feed used passed into production waste. The specific composition of the sediment, in comparison with the feed used, underwent the following changes: in terms of gross energy, the changes amounted to only 14.6%, the lipid content decreased the most, which amounted to 59.6%, the fiber content increased significantly (by 162.4%). The changes in protein were 21.4%. In general, in terms of specific composition and energy value, the collected and analyzed sediment can be considered as a feed potential for many animals occupying a lower stage of the trophic pyramid. The obtained results will allow determining the composition and calculating the number of organisms promising for inclusion in the technological modes of the integrated technologies.