Urban Ponds Research Articles

Addressing the trophic status in urban ponds: An evaluation of current trophic state indexes

AbstractPonds are generally understudied. Quality problems in urban freshwaters can arise from eutrophication, and trophic status classification gives information related to their ecological situation. Ponds may strongly differ from larger lakes for which most current trophic status classification methods have been developed. This paper seeks to compare and contrast the suitability of six trophic status indexes (TSI) and OECD trophic classifications system currently used to evaluate the eutrophication level of urban ponds in the Subtropical region. The trophic status was evaluated based on total phosphorus (TP), soluble reactive phosphorus (SRP), total nitrogen (TN) and phytoplankton chlorophyll a (Chl a) in 12 ponds placed in different cities from the Pampean region (Argentina), in the warm and cold seasons. Our results demonstrate that there was no relationship between pond size (0.08–2.45 ha) and trophic status. TSIs estimated with Chl a showed significant differences between seasons and the range oligotrophic‐hypertrophic of trophism was encountered. Conversely, TSIs estimated with nutrient concentrations (TP, SRP, TN) did not. The pond's classification in trophic levels fell in the eutrophic‐hypertrophic extreme, and only considering TN/TP broadened the trophic range. No relationship was encountered between Chl a and P; however, Chl a and TN/TP were positively correlated during the warm season. Lower trophic levels regarding TSI (Chl a) were generally associated with a dense floating‐macrophyte cover. We suggest that the TSI considered should correspond to the latitudinal region in which the ponds are located. Our results indicate that it appears restrictive to consider only P contents in ponds to assess eutrophication. Under the proposed framework, the key issues for the study of pond trophic classification will be to include not only P but N concentrations and TN/TP. Also, phytoplankton Chl a concentration jointly with floating macrophytes biomass/coverage should be considered as diagnosis parameters.

Latitude-specific urbanization effects on life history traits in the damselfly Ischnura elegans.

Many species are currently adapting to cities at different latitudes. Adaptation to urbanization may require eco-evolutionary changes in response to temperature and invasive species that may differ between latitudes. Here, we studied single and combined effects of increased temperatures and an invasive alien predator on the phenotypic response of replicated urban and rural populations of the damselfly Ischnura elegans and contrasted these between central and high latitudes. Adult females were collected in rural and urban ponds at central and high latitudes. Their larvae were exposed to temperature treatments (current [20°C], mild warming [24°C], and heat wave [28°C; for high latitude only]) crossed with the presence or absence of chemical cues released by the spiny-cheek crayfish (Faxonius limosus), only present at the central latitude. We measured treatment effects on larval development time, mass, and growth rate. Urbanization type affected all life history traits, yet these responses were often dependent on latitude, temperature, and sex. Mild warming decreased mass in rural and increased growth rate in urban populations. The effects of urbanization type on mass were latitude-dependent, with central-latitude populations having a greater phenotypic difference. Urbanization type effects were sex-specific with urban males being lighter and having a lower growth rate than rural males. At the current temperature and mild warming, the predator cue reduced the growth rate, and this independently of urbanization type and latitude of origin. This pattern was reversed during a heat wave in high-latitude damselflies. Our results highlight the context-dependency of evolutionary and plastic responses to urbanization, and caution for generalizing how populations respond to cities based on populations at a single latitude.

Prospects and Challenges of Urban Pond Ecology: A Review

Increase in human population has led to intense pressure on bionetworks that provides various services vital for living organisms survival. This steered to the increase in interest in exploring the panorama and encounters of pond ecology for policy implementation, sustainable utilization that will guarantee sustainable management. This paper review the basic concepts of pond ecosystem, ecosystem service, challenges and prospects of the pond ecosystem. Relevant materials were collected, reviewed and synthesis with a view to understand the level of contribution, area of weakness therefore, the study could contributes in the area. Fish production, irrigation, groundwater storage and discharge, reduction of flash flood and aesthetic were identified as part of ecosystem services rendered by the urban pond. Garden production, research and aesthetic are some of the prospect while, waste disposing site, eutrophication, pollution are considered as some of the challenges confronting pond ecosystem.

The evolution of atmospheric particulate matter in an urban landscape since the Industrial Revolution

Atmospheric particulate matter (PM) causes 3.7 million annual deaths worldwide and potentially damages every organ in the body. The cancer-causing potential of fine particulates (PM2.5) highlights the inextricable link between air quality and human health. With over half of the world’s population living in cities, PM2.5 emissions are a major concern, however, our understanding of exposure to urban PM is restricted to relatively recent (post-1990) air quality monitoring programmes. To investigate how the composition and toxicity of PM has varied within an urban region, over timescales encompassing changing patterns of industrialisation and urbanisation, we reconstructed air pollution records spanning 200 years from the sediments of urban ponds in Merseyside (NW England), a heartland of urbanisation since the Industrial Revolution. These archives of urban environmental change across the region demonstrate a key shift in PM emissions from coarse carbonaceous ‘soot’ that peaked during the mid-twentieth century, to finer combustion-derived PM2.5 post-1980, mirroring changes in urban infrastructure. The evolution of urban pollution to a recent enhanced PM2.5 signal has important implications for understanding lifetime pollution exposures for urban populations over generational timescales.

Структурно-функціональна характеристика фітопланктону, дерновин-подушок, детриту та якість води за дії основних абіотичних чинників ставків міської агломерації (смт Гостомель, Бучанський р-н Київської обл., Україна). Повідомлення І. Видове, таксономічне, екологічне різноманіття фітопланктону та характеристика дерновин-подушок за основних абіотичних складових ставків

The paper deals with phytoplankton quantitative indicators and dominant complex structure, and dimensional and morphological characteristics of detritus particles in the ponds of Hostomel urban settlement. Water quality has been assessed according to phytoplankton characteristics. The phytoplankton abundance made up 2648.0–113675.0 thousand cells  dm–3, and it was mainly formed by Cyanobacteria. The biomass varied within 3.72–16.53 g  m–3, which is indicative of eutrophic waters. The biomass was dominated by Euglenozoa, Miozoa and Bacillariophyta. The dominant complex according to phytoplankton abundance included small-celled Cyanobacteria, according to biomass – large-celled Euglenozoa, Miozoa and Bacillariophyta with a certain share of Cyanobacteria. Different structures of dominant complexes according to abundance and biomass is an important adaptation mechanism of urban ponds phytoplankton. Phytoplankton’s high primary productivity completely fulfils energetic and trophic demands of aquatic organisms at higher trophic levels, and the unconsumed algal biomass is decomposed and transferred to the water column in the form of organic detritus. The organic detritus particles can be ranged into four classes – from minimal < 30 mcm to maximal > 101 mcm, whose biomass can reach 57.60–62.80 mg  dm–3. It indicates that this biological component is very important in forming energy flow, matter circulation and trophic relations. Water quality assessment according to phytoplankton saprobiological characteristics has shown that χ–ο-saprobic and β-mesosaprobic organisms prevailed in the ponds under study. So, the water bodies can be classified within the range “very clean”–“clean” and “moderately polluted” waters. Unlike most urban ponds, the pond network of Hostomel can be considered a quite safe recreation zone from the ecological point of view and is an attractive green space within the urban landscape.

Land uses in cities and their impacts on the water quality of urban freshwater blue spaces in the Pampean region (Argentina).

Freshwater blue spaces (FBS), such as ponds, are key elements of the urban landscape and are under strong anthropogenic pressure. Land-use types and diversity may exert a negative or positive impact on FBS' water quality depending on their nature and arrangement. The information available in this respect is remarkably scarcer for water bodies in the Global South than for the north. Thus, we aim to identify and quantify the land-use types in a 500-m buffer zone of urban ponds in the Pampean region (Argentina) to assess their impact on water quality. We based our study on 15 FBS located in neighborhoods of Buenos Aires province during cold and warm seasons. We analyzed physical, chemical, and biological variables, and estimated water conditions by means of water quality indexes (WQIs) and quality guidelines. We quantified the dominant land-use type and the diversity of uses in the ponds' buffer zones, and evaluated their relationships with WQIs. Our results showed that WQIs were negatively related to a high proportion of residential areas in the adjacent zone, while positively to recreational ones. The diversity of land uses did not influence the water quality. We propose a new WQIpond with fewer key response variables, and as sensitive as the currently used WQIobjetive. We conclude that water quality from urban ponds in the Pampean region can be affected by dominant land-use type in the adjacent area but also the quality of their water supply sources (superficial and/or underground), clandestine wastewater discharges, and non-point pollution.

Effects of urbanization, biotic and abiotic factors on aquatic insect diversity in urban ponds

Urbanization leads to drastic modifications of the terrestrial and aquatic environment. However, urban ponds may provide valuable habitats for different taxa, including aquatic insects and amphibians. We aim to understand how a set of biotic and abiotic factors influence aquatic insect diversity in 18 urban ponds in the German metropolis Berlin, one of the greenest whilst most densely populated European cities. Greenspace is important for the terrestrial stages of some aquatic insects and amphibians, providing crucial resources. Thus, greenspace was assumed to have positive effects on aquatic insect diversity, whereas built-up area was assumed to affect diversity negatively. Because some aquatic insects prey on tadpoles, their abundance and diversity were assumed to depend on tadpole abundance, which in turn, depends on other food (i.e., phytoplankton) availability in ponds. We visited the ponds twice a year, in spring and summer, and collected data on aquatic insects that are known to prey on tadpoles, tadpole abundance, phytoplankton biomass, the presence or absence of large insect predators, as well as physical–chemical parameters. We assumed higher total aquatic insect abundance, genera richness, alpha-diversity, and evenness, as well as abundance and genera richness of different aquatic insect taxonomic groups to be associated with high tadpole abundance in ponds surrounded by high amount of greenspace and low levels of built-up area. Accordingly, we expected aquatic insects to be modulated by phytoplankton biomass, the presence of newts and fish, and to be affected by ponds’ abiotic conditions. Our results showed that biological interactions and abiotic water conditions override urban effects in ponds’ terrestrial surroundings on aquatic insect diversity levels, whereas aquatic insects’ taxonomic groups responded differently on different land-use types around ponds. We explain our findings due to different dependences and demands towards terrestrial and/or aquatic habitats by different taxonomic groups of aquatic insects, and differences in their colonization behavior.

Enhanced nutrient removal in agro-industrial wastes-amended hybrid floating treatment wetlands treating real sewage: Laboratory microcosms to field-scale studies

The use of natural agro-industrial materials as suspended fillers (SFs) in floating treatment wetlands (FTWs) to enhance nutrient removal performance has recently been gaining significant attention. However, the knowledge concerning the nutrient removal performance enhancement by different SFs (alone and in mixtures) and the major removal pathways is so far inadequate. The current research, for the first time, carried out a critical analysis using five different natural agro-industrial materials (biochar, zeolite, alum sludge, woodchip, flexible solid packing) as SFs in various FTWs of 20 L microcosm tanks, 450 L outdoor mesocosms, and a field-scale urban pond treating real wastewater over 180 d. The findings demonstrated that the incorporation of SFs in FTWs enhanced the removal performance of total nitrogen (TN) by 20–57% and total phosphorus (TP) by 23–63%. SFs further enhanced macrophyte growth and biomass production, leading to considerable increases in nutrient standing stocks. Although all the hybrid FTWs showed acceptable treatment performances, FTWs set up with mixtures of all five SFs significantly enhanced biofilm formation and enriched the abundances of the microbial community related to nitrification and denitrification processes, supporting the detected excellent N retention. N mass balance assessment demonstrated that nitrification-denitrification was the major N removal pathway in reinforced FTWs, and the high removal efficiency of TP was attributable to the incorporation of SFs into the FTWs. Nutrient removal efficiencies ranked in the following order among the various trials: microcosm scale (TN: 99.3% and TP: 98.4%) > mesocosm scale (TN: 84.0% and TP: 95.0%) > field scale (TN: −15.0–73.7% and TP: −31.5–77.1%). These findings demonstrate that hybrid FTWs could be easily scaled up for the removal of pollutants from eutrophic freshwater systems over the medium term in an environmentally-friendly way in regions with similar environmental conditions. Moreover, it demonstrates hybrid FTW as a novel way of disposing of significant quantities of wastes, showing a win-win means with a huge potential for large-scale application.

Habitat complexity, connectivity, and introduced fish drive pond community structure along an urban to rural gradient.

Urbanization can influence local richness (alpha diversity) and community composition (beta diversity) in numerous ways. For instance, reduced connectivity and land cover change may lead to the loss of native specialist taxa, decreasing alpha diversity. Alternatively, if urbanization facilitates nonnative species introductions and generalist taxa, alpha diversity may remain unchanged or increase, while beta diversity could decline due to the homogenization of community structure. Wetlands and ponds provide critical ecosystem services and support diverse communities, making them important systems in which to understand the consequences of urbanization. To determine how urban development shapes pond community structure, we surveyed 68 ponds around Madison, Wisconsin, USA, which were classified as urban, greenspace, or rural based on surrounding land use. We evaluated how landscape and local pond factors were correlated with the alpha diversity of aquatic plants, macroinvertebrates, and aquatic vertebrates. We also analyzed whether surrounding land use was associated with changes in community composition and the presence of specific taxa. We found a 23% decrease in mean richness (alpha diversity) from rural to urban pond sites and a 15% decrease from rural to greenspace pond sites. Among landscape factors, adjacent developed land, mowed lawn cover, and greater distances to other waterbodies were negatively correlated with observed pond richness. Among pond level factors, habitat complexity was associated with increased richness, while nonnative fishes were associated with decreased richness. Beta diversity was relatively high for all ponds due to turnover in composition between sites. Urban ponds supported more nonnative species, lacked a subset of native species found in rural ponds, and had slightly higher beta diversity than greenspace and rural ponds. Our results suggest that integrating ponds into connected greenspaces, maintaining riparian vegetation, preventing nonnative fish introductions, and promoting habitat complexity may mitigate the negative effects of urbanization on aquatic richness. While ponds are small in size and rarely incorporated into urban conservation planning, the high beta diversity of distinct pond communities emphasizes their importance for supporting urban biodiversity.

Ecological characterisation of urban ponds in the Netherlands: a study based on data collected by volunteers

Blue space in the urban environment can positively contribute to public health and well-being. Many urban freshwater systems, however, are exposed to anthropogenic stressors, resulting in deteriorated water quality and biodiversity. Private garden ponds are essential elements of this blue space but little is known about their water quality since they are not monitored by water professionals. The Dutch citizen science initiative Waterdiertjes.nl focusses on biological water quality assessment using macroinvertebrates and launched a campaign to investigate garden ponds in 2021. The campaign yielded macroinvertebrate recordings in 60 garden ponds and limited additional information on dimensions, and presence of water vegetation and fish. Volunteers also investigated 92 public urban ponds in 2021. Combining both data allowed for evaluation of the similarity between both pond types. Analyses were also performed to discover the importance of pond dimensions and presence of aquatic vegetation or fish for the macroinvertebrate biodiversity and water quality. Multivariate analyses showed a considerable overlap in macroinvertebrate community composition between garden and public urban ponds. Results showed high variability in taxon richness, total macroinvertebrate density and water quality scores A significant, nonlinear relation was observed between pond depth and macroinvertebrate taxon richness with the highest richness at a depth of 0.5-1m. Submerged vegetation correlated significantly with taxon richness with little vegetation having the lowest richness. Presence of fish or floating vegetation was not significantly related to taxon richness, total density and water quality scores possibly due to unnatural conditions that underlie in garden ponds. Since water professionals and academic scientists do not monitor garden ponds, citizen science may provide valuable data on water quality and biodiversity in these waters. The present initiative showed that volunteers can successfully monitor understudied ecosystems and gather data on temporal and spatial scales complementary to professional data that lead to new (ecological) insights.

Structural and functional characteristics of phytoplankton, algal mats, detritus and water quality under main abiotic factors in urban ponds (case study of urban settlement Hostomel, Bucha district, Kyiv Region, Ukraine). Report І. Species and taxonomic composition, ecological diversity of phytoplankton and filamentous algal mats characteristics under main abiotic factors

The paper considers species and taxonomic composition of phytoplankton and algal mats in ponds of Hostomel urban settlement under effect of main abiotic factors. The research was carried out in May 2021. The ponds under study are shallow and the photic zone occupies the entire water column. The dissolved oxygen content was high. According to nutrient content the ponds are eutrophic. Planktonic algal communities were marked by high diversity. The identified algae referred to 8 phyla, 13 classes, 29 orders, 49 families, 87 genera and 134 species, represented by 136 infraspecific taxa. The floristic diversity at the phylum level was mainly formed by Chlorophyta, Bacillariophyta and Cyanobacteria, at the class level – Chlorophyceae, Bacillariophyceae and Cyanophyceae, at the order level – Sphaeropleales, Euglenida, Chloreallales and Bacillariales, at the family level – Scenedesmaceae, Euglenidae, Bacillariaceae, Selenastraceae and Chlorellaceae, at the genus level – Desmodesmus, Nitzchia, Monoraphidium, Trachelomonas and Euglena. According to biotopic preference planktonic and planktonic-benthic forms prevailed. In Pond ІІІ, floating algal mats were observed. They appeared when benthic communities composed of Charophyta, Bacillariophyta, Chlorophyta and Euglenozoa rose to the water surface. Their cell count reached 28168–368149 thousand cells∙m–2, biomass – 21–362 g ∙ m–2. Algal mats caused a local negative effect due to water column shadowing. High diversity of algal communities makes it possible for pond ecosystems to function even under human impact.

Impact of Bottom-Sediment Removal on 137Cs Contamination in an Urban Pond

Many irrigation ponds in Fukushima Prefecture were decontaminated due to the contamination of radiocesium released from Fukushima Daiichi Nuclear Power Plant. To evaluate the impact of decontamination on 137Cs dynamics in an urban pond in Koriyama City, Fukushima Prefecture, Japan, temporal changes in 137Cs concentrations in bottom sediments and pond water were investigated before and after bottom-sediment removal. Post-decontamination, 137Cs inventories in bottom sediments decreased by 46–89%. 137Cs inventories in bottom sediments were relatively high in fine sediments before decontamination, and were also high at points near the water inlet after decontamination. Following decontamination, the mean 137Cs concentration in suspended solids (SS) and the mean dissolved 137Cs concentration in pond water decreased by 52% and 5%, respectively. Even after decontamination, the normalized 137Cs concentrations in SS and in water, which were calculated by dividing the 137Cs concentrations by the mean 137Cs inventories in each area, were higher than those in rivers, dam reservoirs, and ponds elsewhere in Fukushima. The positive correlations between δ15N values, an indicator of the source contribution to bottom sediments, and 137Cs concentrations in the upper 5 cm of bottom sediments after decontamination implied that SS from urban areas gradually increased the 137Cs inventories in the pond. The results underline the importance of secondary inputs of 137Cs from highly urbanized catchments.

Non‐native fish facilitate non‐native snails and alter food web structure in experimental pond communities

Abstract Contemporary ecosystems commonly support multiple non‐native species, which can alter community structure and directly or indirectly interact with one another. Novel interactions between invasive species can result in the facilitation or suppression of one or both invaders, making it important to understand the underlying mechanisms that affect invasion outcomes. Goldfish Carassius auratus and Chinese mystery snails Cipangopaludina chinensis have been introduced widely through the aquarium trade and co‐occur in their non‐native ranges. We used an outdoor mesocosm experiment to assess separate and combined effects of goldfish and mystery snails on urban pond community structure and to investigate whether goldfish and mystery snails affected one another positively, neutrally or negatively. We predicted that the distinct trophic levels of each species and the anti‐predator traits of mystery snails would lead to positive interactions between invaders and synergistic effects on the aquatic community. Goldfish directly increased turbidity and decreased filamentous algae, zooplankton, juvenile native snails and survival of amphibians via consumptive effects. Goldfish indirectly increased periphyton, phytoplankton and body size of surviving native green frogs Lithobates clamitans through trophic cascades and/or release from competition. Mystery snails had more subtle effects including reducing growth rates of native grey tree frogs Hyla versicolor, likely through competitive interactions. With goldfish present, mystery snails showed increased reproductive success (higher biomass of juveniles), likely due to indirect competitive release from other herbivores. In contrast to their effects on native snails, goldfish did not consume juvenile mystery snails, likely due to their unique traits (e.g. large size and shell thickness). Mystery snails slightly reduced goldfish growth but did not affect their survival. These results suggest unidirectional facilitation between invaders via indirect changes in the food web. Overall, our study found strong direct and indirect effects of invasive aquarium species, particularly goldfish, and provides experimental support for the invasional meltdown hypothesis within urban waterbodies, which are especially prone to invasions. Read the free Plain Language Summary for this article on the Journal blog.

Diurnal pattern and driving mechanisms of the thermal effects of an urban pond

Water bodies are often considered an effective solution to cool their surroundings in hot summers. However, their potential adverse nocturnal warming effect has not yet been investigated thoroughly or considered in current urban planning strategies. This study evaluates the diurnal thermal effects of an urban pond in Nanjing, China, and explores the underlying mechanisms through energy-balance analysis using the Bowen ratio method. In-situ air temperature/humidity, water temperature profile, and upward and downward short- and long-wave radiation on hot summer days were measured. Results demonstrate that compared with a reference soil-site, the pond exerted a moderate daytime cooling effect (0.6 °C) but a pronounced nocturnal warming effect (1.8 °C). During the day, the energy input Rnet (net radiation flux) comprised 77% QS (heat storage) and 23% QE (latent heat flux), while QH (sensible heat flux) was negligible. At night, a negative QS acted as a heat source from the pond, which was released through QH (5%), QE (51%), and Rnet (44%). Results of this study improve our understanding of the thermal effects of urban water bodies, and can be used to inform urban planners and landscape designers regarding implementation of water bodies in the urban context for creating sustainable cool cities and communities.

Microhabitats with emergent plants counterbalance the negative effects of fish presence on diving beetle (Coleoptera: Dytiscidae) diversity in urban ponds

Microhabitats with emergent plants counterbalance the negative effects of fish presence on diving beetle (Coleoptera: Dytiscidae) diversity in urban ponds

Gut Bacterial Communities Vary across Habitats and Their Diversity Increases with Increasing Glucocorticoids in Toad Tadpoles

The gut microbiome is important for host health and can be influenced by environmental and hormonal changes. We studied the interactions between anthropogenic land use, glucocorticoid hormones, and gut bacterial communities in common toads (Bufo bufo). We sampled tadpoles from ponds of three habitat types (natural, agricultural, and urban ponds), examined gut microbiome composition using amplicon sequencing of the 16S rRNA gene, and measured the associated stress physiology using water-borne hormones. Tadpoles from different habitat types significantly differed in bacterial composition. However, bacterial richness, Shannon diversity, and Firmicutes to Bacteroidota ratio did not vary with habitat type. In contrast with other studies, we found a positive correlation between baseline corticosterone release rate and bacterial diversity. Stress response and negative feedback were not significantly correlated with bacterial diversity. These results suggest that, despite alterations in the composition of intestinal bacterial communities due to land-use change, common toad tadpoles in anthropogenic habitats may maintain their physiological health in terms of the “gut-brain axis”.

Where the rare species hide: a new record of Parachironomus monochromus (van der Wulp, 1874) for Slovakia from artificial urban waterbodies

Parachironomus monochromus (van der Wulp, 1874) was recorded for the first time in Slovakia in an urban pond and a city fountain along with a total of 27 other chironomid taxa recorded both as larvae and pupal exuviae. Our finding emphasizes the role of urban waterbodies as habitats for rare species and for maintaining and documenting aquatic biodiversity in cities.

Urbanization affects the taxonomic and functional alpha and beta diversity of fish assemblages in streams of subtropical China

Understanding human-induced changes in biodiversity and the environment can provide important references for managing and conservating freshwater fish. To date, most studies on the influence of urbanization on fish assemblage diversity have focused on large rivers, estuaries, and urban ponds; the process and mechanism of urbanization driving diversity changes in fish assemblages in headwater streams are unclear. We assessed the effects of urbanization on the taxonomic and functional alpha and beta diversity of fish assemblages in the headwater streams of the Xin’an River in China. Our results showed that compared with natural segments, urban segments had higher species richness and lower functional richness, which resulted from the gain of native invasive species and the loss of endemic species; fish assemblages also became taxonomically differentiated but functionally homogenized. In addition, ΔFD (difference value in functional beta diversity between urban and natural segments) was significantly positively correlated with ΔTD (difference value in taxonomic beta diversity between urban and natural segments), whereas only ΔFD was significantly negatively related to the urbanization indicators (e.g. urban land use and ammonia nitrogen concentration). Thus, a combination of taxonomic and functional diversity indices better reveals how fish biodiversity responds to urbanization. Our study provides evidence of urbanization-induced changes in fish assemblages as well as early warning signs for urban-disturbed ecosystems, both of which will benefit fish conservation in headwater streams.

Zooplankton in the temporary recreational pond in microdistrict 13 of Samara

Rotifers make a significant contribution to the self-purification of the water bodies. Full self-purification is especially important for water bodies of recreational zones of settlements. These water bodies are constantly visited by local residents and conditions in these water bodies must comply with sanitary standards and they shouldnt be dangerous to human health. At the same time, the rest of residents on the banks of urban ponds leads to a deterioration in their ecological and sanitary conditions. Therefore, it is necessary to monitor the ecosystems of urban ponds located in recreational areas and among resident buildings. The Rotifera and Crustacea community in the small temporary urban recreational pond in microdistrict 13 of Samara was studied in 2012 and 2018. The pond is situated in the middle of the plot among Kirov avenue, Georgy Dimitrov street, Stara-Zagora street, Moskovskoe highway. 23 Rotifera (13 familia) and 24 Crustacea species (8 familia) have been identified. All species are common for water bodies in the Samara Region. Most of the species live in other ponds of Samara. Brachionidae dominated in the Rotifera community, Cyclopoidae и Daphniidae dominated in the Crustacea. The seasonal dynamics of the population size from May till November was studied. The Rotifers largest abundance in both years was observed in spring and autumn. The crustaceans largest abundance was in 2012 in October, in 2018 in July. The indicator species of Rotifera and Crustacea correspond to the -mesosaprobic zone. While resting people trample grass on the banks, the soil washout causes eutrophication and shallowing of the pond. It is necessary to remove bottom sediments and strengthen the pond banks to improve the state of the pond.

Organic-matter decomposition in urban stream and pond habitats

Organic-matter decomposition is a key ecosystem process in freshwater ecosystems as it influences food web dynamics, represents a considerable flux in the global carbon cycle and can provide a useful measure of the ‘health’ of freshwater habitats. While organic-matter decomposition has been well studied among lotic ecosystems, research from small standing waterbodies such as ponds is largely missing, and decomposition studies are usually conducted on a single freshwater habitat type. However, there is a need to consider ecosystem processes across multiple freshwater habitats and connected ecosystems to better characterise ecosystem functioning at the landscape-scale, given the interdependence of landscape elements. This study provides a comparative analysis of organic-matter decomposition using a standardised field assay (cotton-strip assay) in the water column, riparian zone and land zone of urban pond and stream habitats. The average daily tensile-strength loss of the cotton strips (a process that corresponds to the catabolism of cellulose by microbes) was significantly higher in the aquatic habitats than riparian and land zones when all sites were considered, and when stream and pond sites were considered separately. Furthermore, the average decomposition rate was significantly higher within the water column in river habitats compared to pond habitats, although no difference was observed among riparian and land zones. Woody debris had a negative unimodal association with average per day tensile strength loss within streams, and a positive unimodal association within pond sites. Both nitrate and shading had positive unimodal associations with average per day tensile strength loss within stream sites. Among pond habitat, urban land coverage within 250m of each site was identified to have a negative association with average per day tensile strength loss. Here we demonstrated that urban freshwater habitats have heterogeneous organic matter decomposition rates, and that the responses can be complex. Understanding key ecosystem processes at a multihabitat scale will ensure the effective inclusion of ecosystem process in freshwater assessment and conservation protocols and improve the health and resilience of urban freshwater ecosystems.