Aquatic systems are able to create a nexus of numerous ecosystem services, which are increasingly vulnerable to disturbances taking place in all compartments of the biosphere. Disturbance regimes are leading to fast and profound changes to the landscape with direct and indirect effects to adjacent water bodies. For example, human activities are increasingly altering aquatic ecosystems through direct changes in land use such as mining, urbanization, deforestation, agriculture, and infrastructure projects (eg. hydroelectric dams). Additionally, a variety of natural disturbances including abiotic (erosion, land-slides, wildfires, flooding, drought, hurricanes) and biotic origins (e.g.forest infestation/disease), which their regime and magnitude can also be altered by human/activities are also impacting terrestrial-aquatic linkages. These disturbances in the terrestrial environment are likely to impact the amount and quality of terrestrial materials as well as terrestrial microorganisms transported to nearby waters. Thus, the change in flux of carbon, nutrients, and other elements from land to aquatic ecosystems might, in turn, influence aquatic microbial communities and trophic interactions. However, to what extent all this may have consequences on the biogeochemical cycling, structure and functioning of aquatic ecosystems, is very poorly understood. This session invites any theoretical or empirical studies about the effects of landscape anthropogenic or natural disturbances (alone or in combination with other environmental disturbances) on freshwater and marine ecosystems, with focus on biogeochemical cycles and biological communities (metabolic activity, species composition and interactions). We aim at bridging the disconnect between terrestrial and aquatic processes across variable spatial and temporal scales and provide insight into the environmental, ecological, and social consequences of land effects on aquatic environments.
Lead Organizer: Bianca Rodríguez-Cardona, Université du Québec à Montréal (rodriguez.cardona.bm@gmail.com)
Co-organizers:
Michaela de Melo, Université du Québec à Montréal (michaelaldemelo@gmail.com)
João Henrique Amaral, University of Florida (jh.amaral@gmail.com)
Ada Pastor, Universitat de Girona (ada.pastor@udg.edu)
Clara Ruiz González, Institut de Ciències del Mar (clararg@icm.csic.es)
Presentations
06:30 PM
Precipitation constrains biogeochemical responses of arid land catchments to fire (7506)
Primary Presenter: Alex Webster, University of New Mexico (awebster2@unm.edu)
Wildfires are increasing in severity and frequency, with well-documented, long-term effects on terrestrial ecosystem productivity and recovery, but the effects of wildfire on streams and rivers are less well understood. Most studies that include monitoring of streams post-fire are short-term and, by necessity, are designed to examine changes immediately following a fire event, not quantifying long-term or lagged responses to fire. In arid regions, changing fire regimes are coupled with changing precipitation regimes, potentially compounding disturbance signals and endangering downstream water supplies. We propose a conceptual framework describing how linked accumulation, transformation, transport, and propagation processes influence responses to fire in aridland catchments. We tested components of this framework using pre- and post-fire observations of stream chemistry from watersheds in southern California and northern New Mexico which are two areas with differing precipitation regimes. Using a multivariate autoregressive state-space approach, we demonstrate that changes in stream chemistry (e.g., nutrients and conductivity) due to wildfire can be lagged by up to 3-5 years due to intermittent precipitation. Such effects vary between the two hydroclimatic regimes (i.e., Mediterranean vs. snowmelt/monsoonal). Quantifying effects of feedbacks among fire and precipitation regimes will reduce uncertainty in predicting watershed processes and water quality following arid land wildfire in the Anthropocene.
06:30 PM
Source Categorization of Microbial Communities as a Tracer for Runoff Sources and Timing in an Urban River (7218)
Primary Presenter: Ryan Newton, University of Wisconsin-Milwaukee (newtonr@uwm.edu)
Urban river systems are impacted by a variety of runoff sources, which contain a diversity of pollutants and whose discharge is impacted by the timing and local intensity of precipitation events. Generally, an evaluation of the impact and health risks associated with urban pollutants is deciphered from a single timepoint collection during post-event sampling even though this approach does not match the dynamic nature of landscape contributions to the river. In an effort to better understand the timing and potential coupling of regulated pollutants, we used high-frequency time-series sampling and microbial community characterization to evaluate the sources and linkages between sediment and fecal pollution in an urban watershed. Samples were collected at a single location for 13 separate events across two years, including 11 precipitations periods and two dry weather periods. High-frequency sampling (<4 hr timescale) revealed that fecal bacterial indicator and total suspended solids concentrations were not tightly coupled across storm hydrographs, which indicates unique pollution source origins. We also characterized the microbial community with 16S rRNA gene sequencing and then partitioned the resulting amplicon sequence variants (ASVs) into source environments for sewage, sediment, and freshwater. These data indicated the microbial community undergoes rapid member displacement over short (2-4 hour) timescales. During heavy rain events, >20% of a community’s identified ASVs could be newly arrived between sampling intervals, and these organisms were generally associated with upstream sediment and downstream urban sewage pollution. Ultimately, categorizing source environments for mixed microbial assemblages revealed uncoupled timing of regulated pollutants and the value of high-frequency sampling for understanding the complex dynamics of aquatic-terrestrial interfaces in urban water systems.
06:30 PM
PHYTOPLANKTON COMPOSITION CHANGES DRIVEN BY ENVIRONMENTAL CONDITIONS AND DAM DISCHARGE REGIME IN A TEMPORATE MESOTIDAL ESTUARY (GUADALQUIVIR, SW-SPAIN) (6927)
Primary Presenter: Stefanie Van Bergeijk, (IFAPA) - Centro El Toruño (stefaniea@juntadeandalucia.es)
The Guadalquivir estuary in the SW of Spain plays a vital role as nursery area (fishing reserve) for several species, like anchovies, important for fisheries in the Gulf of Cádiz (Atlantic Ocean), and therefore has been monitored during the last 25 years. It is a highly anthropogenically impacted estuary, subject to dredging for navigation, high nutrient loads and reduced connection to the adjacent marshes, resulting in a high turbidity. A major part of freshwater input (80%) is controlled by a dam situated at 110 km from the estuary mouth. Temporarily high discharges can result in extreme turbidity events, while prolonged low river discharge leads to lower turbidity and higher salt intrusion into the estuary. We studied two sites in the estuary during three years with different dam discharge regimes and evaluated how these changes in environmental conditions affected phytoplankton composition, biodiversity and productivity. A prolonged period of low river discharge resulted in two chl a peaks in summer when normally only one peak is observed. It also led to a higher biodiversity and to the dominance of a previously undetected green alga. Normally, pennate diatoms comprise a considerable part of the phytoplankton, indicating that microphytobenthos may significantly contribute to the water column community. This coincided with a much higher areal gross primary production measured in the intertidal sediment compared to the water column. These data can be used to explain patterns observed in higher trophic levels.
06:30 PM
DYNAMICS OF SEAGRASS (POSIDONIA OCEANICA) FAIRY RINGS (6677)
Primary Presenter: Elvira Mayol Alcover, Mediterranean Institute for Advanced Studies (Imedea - CSIC) (elvira.mayol@imedea.uib-csic.es)
Scale-dependent feedbacks in seagrasses drive multiple spatial patterns at the seascape scale, with clear implications for ecological resilience, functioning, and service provision. Seagrass fairy rings may be a consequence of the accumulation of hydrogen sulfide in the sediment. However, the mechanisms underlying the sulfide-plant interaction for their formation is far from being fully understood. Here, we provide a description of the development of fairy rings of the seagrass Posidonia oceanica in Pollença bay (Mallorca, NW Mediterranean), emphasizing the self-organized dynamics of vegetation under stress. First, we investigate sediment biogeochemical composition and seagrass demography and then, we explore the long-term (1956 - 2020) development of fairy rings by inspecting historical images. We demonstrate that (i) the ring-shaped patches are maintained by inherent vegetation dynamics coupled with sulfide accumulation and (ii) the formation of the ring pattern at the studied area, triggered by ecological feedbacks, coincides with a bifurcation of the ecosystem regime due to sulfide persistent stress.
06:30 PM
Carbon dioxide concentration and evasion from temperate Mediterranean karst lakes (6219)
Primary Presenter: Mariana Vargas-Sánchez, Universidad Nacional Autónoma de México (marianavs@icloud.com)
Quantifying the CO2 emissions by inland aquatic ecosystems of different trophic statuses may provide helpful information about the role of eutrophication on greenhouse gas emissions. The present study evaluated the CO2 emissions in three karstic Mediterranean lakes (Lagunas de Ruidera, Spain). We measured vertical profiles of temperature (T), dissolved oxygen (DO), electrical conductivity, and pH along with dissolved nutrients and CO2 and CO2 flux during early morning, noon, and evening in each lake during the summer of 2021 and winter of 2022. Gas extraction was carried out following the headspace technique, and the CO2 flux was measured using open floating chambers. The results showed a significant seasonal variation in the dissolved CO2 concentration (CCO2) and the CO2 flux (FCO2), but not along the diel cycle (KW, p > 0.05). The CCO2 values ranged from 9.5 to 107.8 µmol L−1 averaging 50.3 ± 15.14 µmol L−1 over the dry/warm season and 34.9 ± 7.8 µmol L−1 over the rainy/cold one. CO2 emissions increased in the dry/warm season (4.2 ± 2.1 g CO2 m−2 d−1), independently of eutrophication (KW, p < 0.05). However, the oligotrophic lake Conceja exhibited the highest FCO2 during the dry/warm season (5.6 ± 1.4 g CO2 m−2 d−1), but during the rainy/cold the highest emission was recorded in the mesotrophic lake Colgada (4.5 ± 1.8 g CO2 m−2 d−1). Our results indicate that temperate karstic lakes are important sources of CO2 driving climate change, particularly due to their correlation with lakes’ trophic status and their high global warming potential.
06:30 PM
Causal networks of phytoplankton diversity at Helgoland Roads (6150)
Primary Presenter: Areti Balkoni, Alfred-Wegener Institute for Polar and Marine Research (areti.balkoni@awi.de)
Phytoplankton diversity is essential for the productivity and functioning of the marine environment. Coastal ecosystems are particularly prone to changes in phytoplankton diversity due to intense anthropogenic activities, and understanding the drivers of this is of primary importance for predicting and managing human-induced impacts. Here, we present a holistic view of the causal network associated with phytoplankton diversity. We aim to elucidate the strongest causal determinant in coastal environments by investigating nutrients; temperature; and plankton abundances. We applied Convergent Cross Mapping (CCM) to the Helgoland Roads time series, one of the most extensive datasets in the world. CCM allows to build a causal network by examining non-linear causal links and pairwise feedbacks, within an empirical dynamic modeling (EDM) framework. Our results show uneven phytoplankton communities dominated by fewer species at Helgoland Roads the last 20 years. We found that SST and N/P ratios are the strongest causal determinants of phytoplankton diversity and that phytoplankton diversity has the potential to impact on nutrient cycling and particularly silicate concentrations and ratios.
06:30 PM
IMPACT OF CONSERVATION PRACTICES ON THE WATER QUALITY OF AN OXBOW LAKE IN THE MISSISSIPPI DELTA, USA: A 25-YEAR ASSESSMENT (6124)
Primary Presenter: Matt Moore, USDA Agricultural Research Service (matt.moore@usda.gov)
Water quality in Beasley Lake, an oxbow of the Sunflower River in the Mississippi Delta, USA, has been assessed biweekly since 1996. Although the lake is surrounded by production agriculture, different conservation practices have been installed and monitored within the watershed over the last 25 years, resulting in decreases of suspended sediment and nutrient concentrations within the lake. Specifically, suspended sediment concentrations have decreased by more than 60% and water clarity has increased more than 100% during the 25-year period. Concentrations of total phosphorus have been reduced 50-70% within the lake, and nitrate-nitrogen concentrations have been reduced by 80%. Total nitrogen concentrations within the lake, however, have not decreased. Current studies focus on within-lake nutrient cycling, management of harmful algal blooms, and the effect of legacy nutrients on lake water quality. Recent assessments suggest the annual release of ammonium and orthophosphate from lake sediments and nitrogen fixation may contribute to observed lag in water quality response following implementation of conservation practices. This unique long-term lake water quality assessment is providing valuable decision tools for landowners, farmers, and conservationists on implementation of conservation practices and their anticipated benefit to water quality.
06:30 PM
BIOCHAR – A NEW WATER PROTECTION METHOD FOR ACID SULFATE SOILS (4944)
Primary Presenter: Niko Kinnunen, University of Eastern Finland (niko.kinnunen1@uef.fi)
Acid sulfate soils cover approximately 17 million hectares globally, and their largest deposits in Europe are found in Finland. They cause a widespread environmental risk of metal pollution and acidity for surface waters, resulting in large-scale mass fish deaths and permanent damage to fish populations, water quality and aquatic ecosystems. Currently, metal export from acid sulfate soils is multiple times larger than that of the entire industry in Finland. Biochar is formed as a side product of biomass pyrolysis, with biogas bio-oils and heat as the main products. It has similar properties to activated carbon yet is much cheaper and easier to produce. Thus, it could be employed as a filter material for adsorbing acidity and metals from water on acidic sulfate sites. We tested the ability of biochar to adsorb metals and neutralize acidity with biochar or biochar-ash-filled reactors. Hundreds of liters of runoff water was circulated through the reactors, and we introduced dilutions to study the desorption of metals. The main research objectives were to study the neutralization of acidity and adsorption of metals with biochar in a setting that resembles field conditions and to determine how including ash alters this. Adsorption was confirmed for multiple metals, and acidity was neutralized. Biochar generally featured slower adsorption for fewer metals than biochar with ash, indicating the importance of the solution pH. If metal was adsorbed, the dilutions did not cause it to desorb back from the biochar. However, ash addition did introduce a release of aluminum.
06:30 PM
BIODIVERSITY TRENDS OF MACROFAUNAL FOULING COMMUNITIES ON TAMPA BAY FLOATING DOCKS (4664)
Primary Presenter: Cassidy Bell, University of South Florida (bellstock13@gmail.com)
Understanding biodiversity trends of highly disturbed urban landscapes is essential as anthropogenic factors continue to drive global biodiversity loss. Within marine ecosystems, macrofaunal fouling communities, aggregations of epibenthic invertebrates that colonize human-made structures, represent an ecologically important subset of urban coastlines. The drivers underpinning their assemblages are unclear, however, as the group remains understudied. This project examines driving factors of macrofaunal community assemblage by analyzing the trends of nearshore fouling communities around Tampa Bay, Florida. Fouling community assessments were completed by performing seasonal scrape analyses at floating docks at ten sites around Tampa Bay during the summer and winter of 2022. The diversity and abundance of invasive species were recorded and analyzed to determine community resilience. Sites were compared based on diversity and dissimilarity indices, and the importance of individual drivers was determined by comparative analysis. This project fills gaps in scientific knowledge surrounding these important urban communities and will lend valuable information to the overall conservation efforts of Tampa Bay.
SS011P Aquatic Ecosystems in the Face of Landscape Disturbances: From Biological Communities to Biogeochemical Cycles
Description
Time: 6:30 PM
Date: 8/6/2023
Room: Mezzanine