The Anthropocene is characterized by rapidly changing environmental conditions. These stressors put increasing pressure on aquatic systems from glacial lakes to the deep ocean and jeopardize the ecosystem services they provide. Stressors also represent altered selective pressures on populations, leading to a range of responses mediated by physiological plasticity, changes in the microbiome, and evolutionary adaptation. These responses can in turn have feedbacks at the population and community level, with potential to both stabilize and destabilize ecosystem dynamics. Along with gradual environmental change, systems can also exhibit abrupt transitions between alternative stable states. Here too, both plastic and evolutionary trait change might have important consequences, although whether they prevent or promote such transitions is still ambiguous. The relative limits of plastic change, and the interactions between phenotypic plasticity and adaptation are also sources of significant uncertainty. In order to predict, plan for, and manage the societal effects of climate change, we need to examine the interplay between acclimation, adaptation, and ecosystem functioning. This session will highlight the diversity of ways in which aquatic organisms respond to environmental change and the resulting consequences for ecosystem resilience and recovery. We will consider responses over a range of timescales and levels of biological organization, from acclimation of cellular processes and individual physiology to rapid microevolutionary adaptation at the level of populations, as well as processes like species sorting at the community level. By bringing together experts from different fields, our session will provide novel insights into how the capacity for rapid responses affects the resilience and recovery of aquatic systems, and the continuity of ecosystem functioning. We explicitly encourage contributions from all aquatic systems, as we look forward to engaging presentations across the salinity gradient from marine to freshwater habitats.
Lead Organizer: Steven Declerck, NIOO-KNAW (s.declerck@nioo.knaw.nl)
Co-organizers:
Jana Isanta-Navarro, Lund University, Department of Biology (jana.isanta-navarro@biol.lu.se)
Lynn Govaert, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) (lynn.govaert@igb-berlin.de)
Matthew Sasaki, University of Connecticut, Department of Marine Sciences (matthew.sasaki@uconn.edu)
Luc De Meester, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) (luc.demeester@igb-berlin.de)
Presentations
06:30 PM
EFFECTS OF A RECIPROCAL TRANSPLANT ON CONDITION INDEX AND GROWTH OF BLUE MUSSELS (<em>MYTILUS EDULIS</em>) AND RIBBED MUSSELS (<em>GEUKENSIA DEMISSA</em>) (4632)
Primary Presenter: Mya Darsan, University at Albany (myadarsan@gmail.com)
Marine bivalves are prevalent suspension-feeders that act as ecosystem engineers. Blue mussels (Mytilus edulis) inhabit intertidal zones of open coasts and attach to hard substrates; ribbed mussels (Geukensia demissa) inhabit intertidal salt marshes and attach to plant roots. While physiological and ecological aspects of both species are well-studied, their response to a sudden change in habitat is not. The project goal was to perform a 4-week reciprocal transplant with M. edulis from UConn Avery Point docks and G. demissa from Barn Island salt marsh to evaluate the impact on the percent shell growth and condition index. Environmental parameters were recorded throughout the experiment. Barn Island displayed variable conditions and higher temperature, total suspended solids, and chlorophyll a. The transplant resulted in no significant change to condition index for either species. A significant reduction in shell growth for M. edulis, but not for G. demissa was observed. G. demissa displayed resilience to the change in environment which indicates they acted as habitat generalists. High seawater temperatures observed at Barn Island can explain the reduction in shell growth for translocated M. edulis. Notably, the condition index of M. edulis did not change in response to the transplant, which may imply that mussels were successfully meeting their basal nutritional needs, but allocated energy towards physiological activities other than shell growth. These results serve to better inform how mussels may respond to climate change and how their ecological roles may be impacted.
06:30 PM
MUSSEL PERIOSTRACUM PROTECTS AGAINST SHELL DISSOLUTION (5638)
Primary Presenter: Alisha Saley, University of California- Davis (amsaley@ucdavis.edu)
Human-derived reductions to seawater pH (ocean acidification), challenge growth and survival of a diversity of marine invertebrates, especially those that calcify. Here we test the role of the outer organic layer of mussel shells (the periostracum) in preventing shell loss in adult California mussels (Mytilus californianus) exposed to reduced seawater pH. We observed that the periostracum inhibits dissolution of mussel shell at each of three levels of pH (7.7, 7.5, and 7.4 on the total scale), with dissolution rates declining by more than 80% if the periostracum remains intact. We also describe how mussels living higher on the shore and at sites exposed to direct sun tend to exhibit decreased cover of periostracum, suggesting accumulated damage from heat and desiccation at low tide could influence the accompanying ability of mussels to cope with pH stress when immersed. Finally, given periostracum is not living tissue and can be eroded over time, for example by sediment scour, we explore how abrasive removal of the periostracum by sands of differing coarseness affects shell loss, documenting a positive relationship between sand grain size and dissolution rate. These findings highlight the importance of considering protective measures marine organisms may employ to confront global change, and how those mechanisms operate in the face of multiple axes of environmental stress.
06:30 PM
FOOD DRIVEN DIFFERENCES IN CONDITION AND POPULATION DYNAMICS BETWEEN TWO COMPETING INVASIVE MUSSEL CONGENERS IN A SHALLOW LAKE ECOSYSTEM (5653)
Primary Presenter: Zoltan Serfozo, Balaton Limnological Research Institute, Eötvös Lóránd Research Network (serfozo.zoltan@blki.hu)
Dreissenid mussels are rapid invaders in temperate freshwaters. Nowadays, competition between the recent newcomer, the quagga mussel (QM), and the zebra mussel (ZM), introduced earlier, can be followed in Lake Balaton, the largest shallow lake in Central Europe. Tracking the population dynamics of the two dreissenids in the past decade, we show the displacement of the ZM by the QM in the food-limited eastern basin, and their co-existence in the food-rich western basin. Chl-A, as an indicator for the mussel food algae concentration, shows a significant drop along the west-east axis of the food-rich western basin (25-4 µg/L) and is uniformly low (2-4 µg/L) in the food-limited eastern basin. Chl-A concentration correlates with carbohydrate and protein content, and with the expression of genes involved in stress response in the QM, whereas inversely relates to lipids, however, only in the western basin. In the food-rich basin, the ZM do not differ from the QM in weight, protein and carbohydrate contents, but have higher lipid content and stress gene expression. After transplantation of mussels from the food-rich to the food-limited basin, the ZM stops growing, and its macromolecular content becomes lower, whereas, despite decreased protein and carbohydrate content, the QM increases its length and lipid content. Results suggest that the QM can better adapt to food limitation than the ZM, likely due to the ability to replace missing storage carbohydrates with accumulated lipids. Change in metabolism could be an important advantage of QM over ZM in their competition.
06:30 PM
MAY RECOVERY COME AFTER INVASION? – BEHAVIOURAL DIFFERENCES BETWEEN ZEBRA AND QUAGGA MUSSELS (5709)
Primary Presenter: Csilla Balogh, Balaton Limnological Research Institute, Eötvös Lóránd Research Network (balogh.csilla@blki.hu)
The dreissenid zebra (ZM) and quagga mussel (QM), which belong to the world’s most successful invaders, endanger native unionid (U) mussels through their intensive biofouling. The two dreissenid species are closely related but different in many aspects. Our goal was to explore the mechanisms underlying interspecific differences in biofouling between them. We investigated size, density, and substratum specificity of dreissenids on different living (U shells) and non-living (stones) substrata, using long-term field datasets of Lake Balaton, Hungary, from the beginning of QM invasion. We carried out lab experiment focusing on the re-colonization and post-settlement movement behavior of dreissenids regarding their substrate preferences. ZM occupies hard objects, especially stones, more often than QM. In contrast, QM more often selects U shells, but also detaches from buried substratum more often than ZM. In the field, ZM was more frequent, its density was higher and its population was more stable than that of QM. Infestation intensity of U in the field by ZM was overall higher than by QM despite the decline of the former. The observed field differences are not considered as recruitment preferences, it rather can be explained by the detachment of QM from substrate. The long term field survey also confirmed that U population may provide shelter for ZM against QM invasion. The pressure on native host species can be lower in those habitats where only QM appears and can be expected to decrease in habitats where the previously introduced ZM has been displaced by the new invader.
06:30 PM
DO INVASIVE SPECIES CHANGE ECOSYSTEM FUNCTIONS IN LAKE CONSTANCE IN AN IRREVERSIBLE WAY? (6254)
Primary Presenter: Piet Spaak, Eawag (spaak@eawag.ch)
Lake Constance, one of the largest Alpine lakes on the border between Germany, Austria and Switzerland, has undergone extensive changes in the past century. In the 1950-1980s, Lake Constance experienced a phase of severe eutrophication, resulting in significantly increased nutrient-levels. Although the natural trophic state of the lake has been restored, there have been irreversible changes to the communities of aquatic organisms. In addition to eutrophication, climate change and especially the invasion of non-native plant and animal species are endangering natural biodiversity. This leads to changes in the food webs and affect ecosystem functioning in Lake Constance. Specifically the three-spined stickleback (Gasterosteus aculeatus) and Quagga mussel (Dreissena bugensis) cause major problems. The stickleback and Quagga mussel populations have exploded in the last years, with sticklebacks becoming the most abundant pelagic fish species. Quagga is able to settle in all water-depths, which causes problems with water intake pipes and other structures. Furthermore, Quaggas are an important competitor for zooplankton feeding on phytoplankton. We hypothesize that the decline in catch yields and fisheries in Lake Constance is caused, by these two invasive species. We present a large EU funded project (SeeWandel) that i.a. investigates causes and consequences of such invasions for Lake Constance. We present latest results about those invasive species and its consequences for the lake.
06:30 PM
Remaining aquatic systems of the Aral Sea between “slow death” and fast recovery: ecosystem response to extreme variations in vertical mixing (5203)
Primary Presenter: Georgiy Kirillin, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (georgiy.kirillin@igb-berlin.de)
Desiccation of the Aral Sea, the former 4th largest lake by area, is an unprecedented example of fast anthropogenically driven degradation of a large aquatic ecosystem. As a countermeasure preventing further desiccation, a 12-km long dam was constructed isolating the northern part of the Aral Sea from the rest. The “restarted” North Aral had been restored within several years from a “dying” ecosystem to a highly productive large lake. The effort led to stabilization of the North Aral volume, and was widely recognized as a success in large-scale lake restoration. As a side effect of restoration measures, part of the freshened waters overflowed into remaining semi-isolated lakes, causing them to become meromictic and creating extreme environments with strong vertical gradients of salinity, light and temperature. The deep layers of these lakes quickly developed to anaerobic environments dominated by methanogenic and sulfate-reducing microorganisms benefiting from a large amount of organic matter. By using outputs of field observations and modeling results we demonstrate the decisive role played by the mixing conditions in ecosystem adaptation to external drivers. While the North Aral Sea is restored to the well-mixed state similar to that before its desiccation started, its seasonal mixing regime is currently in unstable equilibrium, wobbling between polymictic and dimictic conditions. The fragility of this seasonal pattern is demonstrated by modeling results: slight changes of the water level or transparency may turn the Aral Sea to steadily dimictic or polymictic state.
06:30 PM
Extensive carbon contribution of inundated terrestrial plants to zooplankton biomass in a eutrophic lake (7226)
Primary Presenter: Yali Tang, Jinan University (yalitang@jnu.edu.cn)
Organic carbon derived from terrestrial plants contributes to aquatic consumers e.g., zooplankton in lakes. The degree of the contribution depends on the availability of terrestrial organic carbon in lake organic pool and the transfer efficiency of the carbon. Terrestrial organic carbon is poor-quality food for zooplankton with a mismatch of nutrition content and was incorporated to zooplankton with much lower efficiency than phytoplankton. Contributions of terrestrial carbon to zooplankton generally decrease with an increase in phytoplankton production indicating a preferential incorporation of phytoplankton in previous investigations. However, in eutrophic lakes, the dominating cyanobacteria were of poor-quality and incorporated to consumers inefficiently too. In that case, zooplankton in eutrophic wetlands, where cyanobacteria dominate the phytoplankton production and massive terrestrial plants are inundated, may not preferentially incorporate poor food-quality phytoplankton resource to their biomass. Therefore, we hypothesize that carbon contributions of terrestrial vegetation to zooplankton and to lake particulate organic pool should be similar in in such aquatic ecosystems. We tested this hypothesis by sampling zooplankton and carbon sources in Ming Lake (Jinan University campus, southern China) which was overgrown by terrestrial plants after drying and re-flooded. After 60 days of observations at weekly (or biweekly) intervals, applying stable carbon (13C), nitrogen (15N) and hydrogen (2H) isotopic analysis and a stable isotope mixing model, we estimated the occurrence of extensive carbon contribution (≥50%) of flooded terrestrial plants to cladocerans and copepods. Contribution of inundated terrestrial plants to cladocerans was similar to that to lake particulate organic pool. Thus, our study quantified the role of terrestrial carbon in eutrophic wetlands, enhancing our understanding of cross-ecosystem interactions in food webs with an emphasis on the resource quality.
06:30 PM
HEAVY METALS CAN AFFECT RESTING EGGS BANK PERFORMANCE (6803)
Primary Presenter: Alejandra Sanchez Avila, The University of Texas at El Paso (asanchezav@miners.utep.edu)
Dormant egg banks play important roles in zooplankton community resilience and recovery. Resting eggs, like heavy metals, tend to accumulate, and their production can be a strategy to avoid pollutants. To test the hypothesis that pollutants can affect dormant populations, we exposed diapausing eggs of the freshwater rotifer Brachionus calyciflorus to 4 concentrations of copper (0.003, 0.03, 0.18 and 4 mg L-1 of CuSO4) and a control. After hatching, one set of neonates from each treatment was placed in the control medium; and another set was re-exposed to the same concentration as the hatching treatment. Preliminary results showed a significantly higher proportion of failed hatching (5 - 30%) and post-hatching mortality (51 – 82%) in the 0.18 and 4 mg L-1 treatments than in other treatments (> 2%), resulting in a lower percentage of viable offspring (<14%) at these concentrations. We also found that neonates from the control and the 0.003 mgL-1 treatments had significantly longer lifespans (mean + SD: 13.5 + 5.2 days) and offspring per female (11.6 + 5.2 neonates) than the single exposure treatments (7.4 + 5 days; 5.5 + 4.4 neonates) and the re-exposure treatments (2.0 + 2.0 days; 1.0 + 1.0 neonate). These results suggest that at high concentrations copper can affect resting egg banks and the future performance of active populations, thereby negatively affecting zooplankton communities.
06:30 PM
SHORT-TERM AND MULTIGENERATIONAL EFFECTS OF TEMPERATURE ON INGESTION AND EGG PRODUCTION RATES OF THE MARINE COPEPOD PARACARTIA GRANI (4840)
Primary Presenter: Enric Saiz, Institut de Ciències del Mar (ICM-CSIC) (enric@icm.csic.es)
Temperature is one of the most prominent climate-change variables affecting marine zooplankton activity and distribution. The impact of warming on zooplankton depends not only on physiological sensitivity, but also on the temporal scale of exposure and the species acclimation capacity. Warming events of a few days or weeks of duration will mainly impact at the intragenerational level, while longer-term warming will reflect on multigenerational responses. In this study, we compare the effects of +3 and +6ºC thermal stress on the vital rates of the copepod <em>Paracartia grani</em> at short (2 and 7 days, acclimation response) and long (>10 generations, multigenerational response) time scales. <em>P. grani</em> showed high phenotypic plasticity after 2-d exposure, increasing feeding and egg production rates. This acute response, however, declined quickly and after 7 days of exposure the enhancement of physiological rates was still positive but of lesser magnitude (Q<sub>10</sub> <2). Multigenerational rearing at the tested temperatures resulted in a further reduction of the copepod response to temperature and the apparent loss of thermal effects, implying further adaptive compensation processes. The metabolic costs of the thermal responses, estimated as the copepod gross-growth efficiency, did not appear to be influenced by temperature, suggesting the species has high thermal tolerance.
06:30 PM
DOES THE TEMPERATURE-SIZE RULE APPLY TO MARINE PROTOZOANS? (4796)
Primary Presenter: Albert Calbet, Institut de Ciències del Mar - CSIC (acalbet@icm.csic.es)
The temperature-size rule proposes there is a negative relationship between the size (volume) of an ectothermic organism and the environmental temperature experienced during its development. We question how to validate this hypothesis for the particular case of protozoans because in these unicellular organisms body volume is directly related to the consumption of prey and, on most occasions, the true volume of the cell is unknown. In our opinion, to approach this question, the actual size of the protozoan should be measured when prey are fully digested. To prove our arguments, we designed a series of experiments with the heterotrophic dinoflagellate <em>Oxyrrhis marina</em>, including functional and numerical responses, estimation of the protozoan volume during starvation, and time-dependent acclimation responses. We found that after the digestion of the prey, the size of <em>Oxyrrhis marina</em> was the same regardless of the temperature. We believe that the previous reports on the temperature-size rule using protozoans that show important cellular volume changes because of feeding are biased by imbalances between ingestion and digestion of prey. These imbalances disappear after sufficient acclimation.
06:30 PM
Resilience of Seagrass Phyllosphere Microbiomes to Antibiotic Stressors (7056)
Primary Presenter: Ryan Mueller, Oregon State University (muellery@oregonstate.edu)
Seagrass microbiomes can play pivotal roles in the health and nutrition of the host plant, but are subject to disturbance due to environmental changes and exposure to stressors. To examine the resilience of leaf microbiomes we performed mesocosm experiments with Z. marina shoots where plants were exposed to different antibiotics and dosages for 48 hours and then the recovery of the microbial communities was tracked over time. All antitbiotic treatments led to an intital and strong decrease in alpha diversity and significant changes to the community structure of leaf microbiomes as compared to those from unexposed control plants. Following this disturbance, alpha and beta diversity metrics rapidly return to the level of control plants. These findings that antibiotic-induced stress strongly impacts the leaf phyllosphere community of seagrasses, but that the microbiome is resilient to disturbance and rapidly recovers to a non-stressed state within 16 days.
06:30 PM
Clear-water state restoration in a subtropical eutrophic urban lake: overcome the negative resilience in a turbid-water state (6266)
Primary Presenter: Zhengwen Liu, Nanjing Institute of Geography and Limnology (zliu@niglas.ac.cn)
Loss of submerged macrophytes and high biomass of benthivorous/planktivorous fish are main factors contributing to the resistance of shallow lakes to the reduction in external nutrient loadings in tropical and subtropical China. Our large scale (30 hectares) experiment in subtropical Lake Yanglan showed that removal of benthivorous/planktivorous fish and flocculation by polyaluminium chloride (PAC) and lanthanum modified bentonite (Phoslock®) resulted in an immediate increase in water transparency (secchi depth up to 2 m) and decrease in total phosphorus (TP) (down to 50 µg/L), creating conditions for macrophyte growth. Follow-up transplanting of submerged macrophytes re-established a clear-water state in this urban lake. Although the restoration led to occurrence of large sized cladoceran Daphnia sp., but they disappeared in early summer which likely due to the recovery of young-of-the year fish in the restored area. Our results suggest that submerged macrophyte dominance could be restored by fish removal plus chemical flocculation followed by plant transplantation in this warm lake.
SS113P Resilience and Recovery in Aquatic Systems: The Impacts of Rapid Acclimation and Adaptation
Description
Time: 6:30 PM
Date: 7/6/2023
Room: Mezzanine