Ponds are aquatic systems with small surface area (< 5 ha) and shallow depth (< 5 m). Even though these systems are numerous in almost any landscape worldwide, they have received less attention than larger lakes and rivers. Despite their small size, these systems have enormous global importance as they promote biodiversity, play key ecosystem functions, and connect the waterscape acting as stepping-stones in the dispersal of local species. However, their small size also makes them fragile and susceptible to impacts due to global change and other anthropogenic stressors (i.e. agriculture or urbanization) that can alter their water balance and eventually lead to their disappearance. For this session, we welcome both empirical (including a wide variety of ponds and pools) and experimental work (in the form of micro- or mesocosms), in addition to simulations and theory, focusing on population, community, or ecosystem scales in these understudied systems.
Lead Organizer: Zsofia Horvath, Institute of Aquatic Ecology, Centre for Ecological Research (hhzsofia@gmail.com)
Co-organizers:
Dunja Lukić, Research Department for Limnology, University of Innsbruck, Mondsee, Austria (dunjalkc@gmail.com)
David Cunillera-Montcusí, GRECO, Institute of Aquatic Ecology, University of Girona, Girona, Spain & FEHM-Lab (Freshwater Ecology, Hydrology and Management) Section of Ecology, Department of Evolutionary Biology, Ecology and Environmental Sciences University of Barcelona & Departamento de Ecología y Gestión Ambiental. Centro Universitario Regional Este (CURE). Universidad de la República (david.cunillera@dcm.cat)
Dani Boix, GRECO, Institute of Aquatic Ecology, University of Girona, Girona, Spain (dani.boix@udg.edu)
Presentations
10:30 AM
TRANSPORT AND MIXING IN PONDS (7294)
Primary Presenter: Stephen Henderson, Washington State University (Vancouver) (steve_henderson@wsu.edu)
We present a descriptive overview of summertime transport and mixing in two ~50-m-long temperate ponds. Observations were motivated by examination of the spatial and temporal distribution of Environmental DNA, but also have broader ecological and biogeochemical implications, because ponds are characterized by high biodiversity and intense biogeochemical processing. Two distinct layers were observed, with very different patterns of transport and mixing. In the upper “Surface Mixed Layer” (SML), currents reached a few cm/s, flowing downwind near the surface and upwind near the SML base. Vertical turbulent mixing was sufficient to homogenize this layer in about 0.5 hours, comparable to the time required for currents to transport water across the pond. Below the SML, in a “Stratified Layer” (SL), mm/s currents usually reversed several times per hour, gravity held light warm water above cold dense water, and vertical turbulent mixing was negligible. Nightly free convection increased SML depth to >1 m, whereas daytime heating often reduced SML depth to <0.5 m, with the shallowest depths observed near the upwind shore. Implications for biogeochemical transport are discussed. Observations suggest that the deeper (>1.6 m) regions of observed ponds were not ventilated through most of the summer, although creation of bottom water by preferential cooling in shallows may complicate this theory. The small SML thickness, and the similarity of timescales for vertical mixing and lateral advection, both suggest that applicability of popular one-dimensional vertical parameterizations for surface fluxes may be limited to shallow depths in small water bodies. A simple parameterization for SML depth is shown to be useful for distinguishing the upper region of rapid transport and mixing from the lower, quiescent layer.
10:45 AM
RESTORATION OF THREE IRISH EUTROPHIC LAKES USING PHOSPHORUS FIXING CHEMICALS (4666)
Primary Presenter: Juan Bennett, Ulster University (bennett-j7@ulster.ac.uk)
In the last decades, phosphorus (P) fixing chemicals have been applied in shallow lakes to counteract eutrophication. The retention of P in the sediments and the cessation of the internal loading process are key to this technique’s success. The longevity of treatments has been varied and reasons for failures have been usually linked to inadequate control of external sources of nutrients or incorrect calculation of chemical remediation doses, among others. In this study, an aluminium sulphate (alum) restoration has been implemented in the 2021-2022 winter, in three shallow eutrophic lakes located in Ireland. The dosing of the lake’s surface was evenly performed by means of a boat that was equipped with a container which stored the alum and a chemical pump. Water quality measurements were regularly performed with a water sampler and a multiparameter sonde. The three lakes showed an immediate decrease in the chlorophyll a concentration after the alum dosing. Moreover, the summer chl a peaks, that were present in 2021 (up to 190 μg/l), didn’t appear in summer 2022, with concentrations not exceeding 30 μg/l for any of the lakes. In the same way, total phosphorus peaks experienced in summer 2021 (up to 283 μg/l) didn’t occur one year later. The alum did not trigger major alkalinity drops or pH modifications in the water column of these ecosystems. Next steps will consist of further water parameter monitoring and analysing aluminium concentrations of gills, muscle and liver in fish captured before and after the dosing to assess the potential biological impact of the restoration.
11:00 AM
Balancing cultural heritage and water quality in aquaculture ponds (7320)
Primary Presenter: Björn Wissel, Université Claude Bernard Lyon 1 (bjoern.wissel@univ-lyon1.fr)
With over 1,100 ponds, la Dombes (Ain, France) is the largest inland fish-producing region of France. Traditional fisheries-management approaches have been established over the past 500 years. Yet, climate change and intensified land-use are now threatening water quality, biodiversity as well as fisheries yield. In 2022 we studied 22 ponds for invertebrate biodiversity, greenhouse gas dynamics and microplastics. While we found no differences between the most common management practices (fertilize+feed+lime vs. fertilize+feed), unmanaged reference ponds showed contrasting patterns. Invertebrate richness and diversity were higher in unmanaged vs. managed ponds, but so were CO2 emissions. For CH4, emissions were elevated across all ponds. Initially, it was surprising that unmanaged ponds had the highest carbon emissions. Yet, the quinquennial draining of managed ponds combined with farming may prevent the accumulation of organic material. Microplastic concentrations in the water column were some of the largest observed in inland waters, with highly dynamic temporal and spatial patterns. Long-term-Ecological-Research will be vital to quantify the importance of hydrology, management and land use for the functioning and controls of these systems. Ultimately, this work will support the co-development of best-management practices to increase ecosystem services while maintaining fish yield.
11:15 AM
From communities to individuals: the different levels of impacts of organic and conventional agriculture on pond biota (6680)
Primary Presenter: Rafaela Almeida, KU Leuven (rafaela.almeida@kuleuven.be)
Agriculture is a key driver of global land use change and profoundly affects natural ecosystems. Although organic agriculture is promoted as a more environmentally friendly alternative to conventional agriculture, how impacts differ between both farming systems is still debated. Comparative studies focus mainly on terrestrial systems and rivers, whereas small lentic waterbodies, like ponds, are ignored. This is despite the fact that ponds are abundant in agricultural landscapes, largely contribute to regional biodiversity, and are very sensitive to environmental change. Here we compare the impact of conventional and organic agriculture on biodiversity and evolutionary trajectories of pond biota. First, we compared α, β and γ-diversity of macrophytes, zooplankton and macroinvertebrates in ponds located in organic and conventional farms. We found a moderately positive effect of organic farming on aquatic biodiversity, particularly for macrophytes and at larger spatial scales, but the variation in biodiversity among ponds irrespective of agricultural type indicates that other factors such as land use intensity might be more important for biodiversity. Then, we assessed whether Daphnia magna populations from organic and conventional farmland ponds genetically adapt to specific types of pesticides used in each agriculture type. We found that D. magna populations differentially adapt to pesticide use in organic and conventional farming. These results show that both types of agriculture exert different selection pressures that impact the genetic features of non-target species.
11:30 AM
MOSQUITOES WITHIN AQUATIC MACROINVERTEBRATE COMMUNITIES OF URBAN PONDS ALONG AN URBANIZATION GRADIENT (5344)
Primary Presenter: Irene Tornero, Institute of Aquatic Ecology, Centre for Ecological Research (irene.tornero@udg.edu)
Mosquitoes in urban environments are considered unpleasant by citizens and they can represent serious health risks as disease vectors. Furthermore, invasive Aedes species are continuously spreading in Europe and have been increasingly reported from urban settlements. Some of these mosquito species have been associated with small artificial habitats, e.g., dark plastic containers. Therefore, we could also expect their presence in small plastic garden ponds, which are numerous in urban settings in several parts of Europe. In this study, our aim was to understand the potential abiotic and biotic drivers of the presence of mosquitoes within the macroinvertebrate communities in urban ponds. We sampled 54 public urban ponds in Budapest (Hungary) of both natural and anthropogenic origin and 40 garden ponds which cover both highly urbanized areas and those with high green index in the suburbs. We collected data on the macroinvertebrate communities of these ponds as well as data on management along with physico-chemical parameters and pond features (mainly morphology and vegetation cover) measured in situ during spring 2022. While we did not find any invasive mosquitoes in the 94 ponds, several other species were present, including Anopheles plumbeus, a potential malaria host spreading in urban environments. Macroinvertebrate communities varied between the two main habitat groups and both morphology and management played a key role in community composition.
11:45 AM
Changes in lentic macrophyte flora over three decades in Pyrenean shallow lakes and ponds (7205)
Primary Presenter: Esperança Gacia, CSIC (espimartijin@hotmail.com)
High mountain water bodies are ecosystems that are highly sensitive to global change, due to their remoteness and distance to human activities. The Pyrenean limnological district holds hundreds of water bodies, with a substantial amount harboring shallow aquatic macrophytic assemblages. Previous studies indicated that Pyrenean aquatic macrophytic flora maintained their biodiversity and richness throughout the 20th century, even though acidification and regional eutrophication were severely threatening these assemblages from Center and Northern Europe. Nevertheless, signs of eutrophication and biodiversity decline have become apparent in recent times. Here we conduct a regional assessment of macrophyte flora inventories of 30 Pyrenean shallow water bodies and compare submersed vegetation inventories across a 30+ year period to directly assess vegetation shifts and possible changes in water column environmental parameters related to regional and/or local eutrophication. We use semi-quantitative data for a total of 33 taxa and a set of environmental data, starting before 1990 and revisiting after 2018, with the aim to analyze trends in aquatic plant abundance and depth distribution, water body richness and biodiversity changes occurring over more than three decades. Preliminary results indicate that most of the taxa studied remain stable, without significant changes. However, Potamogeton berchtoldii and Myriophyllum alterniflorum are expanding by the colonization of new lakes, while Isoetes creussensis and I. echinospora tend to slightly expand within systems. On the contrary, Sphagnum spp. and Subularia aquatica seem to be less frequent. We have not been able to find significant trends between the observed changes and the environmental factors considered.
SS092B The Relevance of Small Systems: Pond Ecology in a Changing World
Description
Time: 10:30 AM
Date: 5/6/2023
Room: Sala Menorca B