Accurately predicting organismal responses to climate change is essential for the conservation of global biodiversity. The variability of environmental conditions on spatial (from organism to ecosystem scale) and temporal (hours and days to months and years) is a central factor determining the resilience and recovery of marine organisms and populations under climate change. However, the majority of research quantifying and predicting the response of marine organisms to climate change is performed under static (or average) environmental conditions and therefore does not account for environmental variability. This special session welcomes empirical research that incorporates environmental variability (e.g., of temperature, dissolved oxygen, pH, currents, waves, nutrients, etc.) to assess the susceptibility of marine biota to current and future climate change in experimental approaches or quantifies its spatio-temporal scales in marine habitats. We invite researchers who bring together methods or data from various disciplines to answer questions that address short- and long-term fluctuations in the marine physical environment and its intersection with the phenotype of organisms inhabiting a wide range of marine habitats. Studies that describe historical, current, and projected ocean environmental variability under different scenarios of greenhouse gas emissions are also welcome.
Lead Organizer: Andrea Anton, Mediterranean Institute for Advanced Studies (IMEDEA), CSIC-UIB, Spain (andrea.anton@imedea.uib-csic.es)
Co-organizers:
Maren Ziegler, Justus Liebig University Giessen, Germany (Maren.Ziegler@bio.uni-giessen.de)
Presentations
10:30 AM
Macroalgae affects the metabolic performance and behaviour of the sea urchin Paracentrotus lividus along a thermal gradient (6662)
Primary Presenter: Andrea Anton, IMEDEA (UIB-CSIC) (andrea.anton@imedea.uib-csic.es)
Organisms are highly sensitive to global warming, which especially threatens marine organisms. Marine vegetated habitats provide dial fluctuations of oxygen, creating hyperoxic environments during the day that could potentially increase the resistance of organisms to thermal stress. Although these habitats provide food and shelter for many marine organisms, we lack an understanding of the potential benefits of naturally occurring dial oxygen fluctuations on temperature-sensitive marine biota. We experimentally tested if dial fluctuation of oxygen affects the metabolic performance and behaviour of the sea urchin Paracentrotus lividus. Sea urchins were exposed to dial-oxygen fluctuations produced by macroalgae for 11 days at 5 targeted temperatures (20, 23, 26, 29, and 32 oC). We found that respiration rates at the optimal temperature (29 oC) doubled at the peak of oxygen concentration during the day (2.72 mg O2 h-1 urchin-1) than at the valley of oxygen concentration at night (1.41 mg O2 h-1 urchin-1). Oxygen concentration also affected the behavioral response of the sea urchin, where we found shorter righting response (time to turn from the aboral side to the oral side) on urchins during the peak of oxygen (average 218 s) than at the oxygen valley (average 280 s). This study reveals that marine vegetated habitats induce changes in oxygen concentration that might critically affect the metabolic performance and behaviour of marine organisms along a thermal gradient.
10:45 AM
The influence of abiotic and biotic conditions on lifecycle stages is critical for estuarine seagrass resilience (5349)
Primary Presenter: Chanelle Webster, Edith Cowan University (chanelle.webster@ecu.edu.au)
Environmental variability influences seagrass resilience, but the strength and relative importance of factors are rarely assessed over the complete lifecycle. This study examined the effects of abiotic (salinity, temperature, water depth) and biotic (grazing by black swans) factors on Ruppia spp. over the complete lifecycle. Structures were set up in two estuaries that prevented and allowed natural swan grazing of the seagrasses, before the start of the growing season. The density of life stage(s) were measured from germination to senescence. Our results showed that swans impacted some but not all life stages. Seedling densities were significantly higher in the plots that allowed natural grazing compared to the exclusion plots (e.g. 697 versus 311 seedlings per m-2). Swans removed ≤10% of seagrass vegetation but a dormant seedbank was present and new propagules were also observed. We conclude that grazing by swans provides some benefit to seagrass resilience by enhancing seedling recruitment. We further investigated the drivers of the different lifecycle stages using general additive mixed models. Higher and more variable salinity led to increased seed germination whilst temperature explained variation in seedling density and adult plant abundance. Bet-hedging strategies of R. polycarpa were identified including a dormant seedbank, continuous germination and seedling emergence over variable conditions (salinity 2-42 ppt; temperatures 11-28°C). These strategies may be key determinants of resilience to emerging salinity and temperature regimes from a changing climate.
11:00 AM
Assessing vulnerability and resilience of shellfish in dynamic multi-stressor intertidal habitats using high-frequency non-invasive sensors (6226)
Primary Presenter: Nils Volkenborn, Stony Brook University (nils.volkenborn@stonybrook.edu)
Suspension feeding bivalves play a critical role in many coastal ecosystems. In intertidal habitats, major environmental factors such as T, DO, pH, salinity, or food availability can vary rapidly on time scales of minutes to hours over the slightly shifting day-night and tidal cycles, creating a wide range of possible multi-stressor scenarios and sequences. For example, in estuaries around Long Island, NY, the ribbed mussel (Geukensia demissa), a keystone species in saltmarsh ecosystems along the east coast of the US, can be exposed to pronounced hypercapnic hypoxia during summer nighttime high tides in parallel with daily temperature ranges of 20 °C. Many traditional measures of shellfish performance only provide snapshots of shellfish condition and do not capture behavioral or physiological responses with temporal resolutions that match the dynamism of the environment. This presentation will highlight the potential of high-frequency, non-invasive sensors to record heartbeat rates and valve gaping behavior in-situ and during laboratory stress tests to fill this knowledge gap. While ribbed mussels seem well-adapted to cope with a large degree of environmental variability, identifying environmental thresholds that relate to non-lethal stress and the ability to recover from sequential or re-occurring multi-stressor events is critically needed to predict tipping points in changing coastal oceans that can lead to shellfish population collapse, resulting in altered ecosystem function and loss of ecosystem services provided by these keystone species.
11:15 AM
CARBONATE CHEMISTRY IN THE MICROENVIRONMENT WITHIN CYANOBACTERIAL AGGREGATES UNDER PRESENT-DAY AND FUTURE PCO2 LEVELS (5319)
Primary Presenter: Meri Eichner, Institute of Microbiology CAS (eichner@alga.cz)
Within cyanobacterial aggregates, photosynthesis and respiration can cause steep chemical gradients at micrometer scale. Variations in photosynthetic activity with light and over the diel cycle, in turn, shape a highly dynamic microenvironment. Here, microsensors and a diffusion–reaction model were combined to characterize the gradients in carbonate chemistry within Baltic vs. Pacific aggregates (Nodularia and Dolichospermum vs. Trichodesmium) under present-day and expected future pCO2 levels. Under in situ conditions, O2 and pH levels within aggregates of Nodulariaand Dolichospermum collected in the Baltic Sea ranged between 80 and 175% air saturation and 7.7 and 9.4 in dark and light, respectively. Carbon uptake in the light was predicted to reduce HCO3− by 100–150 μmol L−1 and CO2 by 3–6 μmol L−1 in the aggregate center compared to outside, inducing strong CO2 depletion even when assuming that HCO3−covered 80–90% of carbon uptake. Under ocean acidification conditions, enhanced CO2 availability allowed for a significant reduction in the contribution of HCO3− to carbon uptake. The magnification of proton gradients under elevated pCO2 that was predicted based on the lower buffer capacity was observed in measurements despite a decrease in photosynthetic activity. Taken together, this dataset provide a quantitative image of the variable inorganic carbon environment in cyanobacterial aggregates under present-day and expected future conditions.
11:30 AM
THERMAL FLUCTUATIONS MODIFY THE EFFECTS OF WARMING ON MARINE PHYTOPLANKTON: EXPERIMENTAL RESPONSES ACROSS DIFFERENT PHYLOGENETIC GROUPS. (6631)
Primary Presenter: Osvaldo Tascón, University of Vigo (osvaldo.tascon@uvigo.gal)
Understanding the effect of temperature on phytoplankton ecophysiology is key to predict the effects of global warming on the productivity of aquatic ecosystems. More than a century ago, Jensen stated, through the fallacy of the average, that the response of a given system to constant conditions is seldom equal to its mean response to variable ones. We thus hypothesized that a thermally fluctuating environment may cause changes in phytoplankton growth, stoichiometry and metabolic rates that differ from the effect of constant warming. To test this hypothesis, we exposed five phytoplankton species (Emiliania huxleyi, Micromonas commoda, Skeletonema costatum, Synechococcus sp. and Thalassiosira rotula) to a 2x2 full-factorial design with two temperatures (control vs. warming) and two thermal regimes (constant vs. fluctuating). We found that thermal fluctuation stimulated photosynthesis whereas constant warming reduced it when compared to control conditions. Biomass-based growth rates under constant warming increased in E. huxleyi, M. commoda and Synechococcus but decreased in S. costatum and T. rotula. In general, thermal fluctuations tended to cause a decrease in growth rates, or a reduction of the positive effect of warming. The carbon to nitrogen ratio often increased under warming, but tended to decrease under thermal fluctuation. We conclude that fluctuations alter the effect of temperature on the metabolism, growth and stoichiometry of phytoplankton, but the observed responses are different depending on the species.
11:45 AM
BIODIVERSITY EXPOSURE TO PROJECTED CLIMATE CHANGE MAY COMPROMISE FUTURE MARINE PROTECTED AREA RESILIENCE UNDER BUSINESS-AS-USUAL SCENARIO (6522)
Primary Presenter: Milica Predragovic, Centro de Ciências do Mar do Algarve, University of Algarve (mpredragovic@ualg.pt)
Climate change disrupts marine organisms through temperature and chemistry changes, challenging their ability to adapt and survive. While marine protected areas (MPAs) aim to protect marine species and habitats, climate change impacts are often neglected during their design and implementation, raising questions about their long-term effectiveness. We evaluated the resilience to climate change of threatened species and species targeted by fisheries in European MPAs by assessing their exposure to novel climates using climate dissimilarity based on four environmental variables (temperature, oxygen, pH, and primary productivity) coupled with projections of species distributions, from present-day conditions to the end of the 21st century, under contrasting Shared Socioeconomic Pathways (SSP) scenarios (SSP1-1.9 and SSP5-8.5). Results show that 6.6% of the species and 0.5% of European MPAs will experience novel climates under SSP1-1.9, and 82% of species and 87% of MPAs under business-as-usual scenario (SSP5-8.5). Most species from MPAs in enclosed and semi-enclosed basins like the Baltic Sea and the Black Sea seem to be exposed to the highest degree of novel climatic conditions. Incorporating future climate change projections into management plans, including protection of possible climate refugia, and meeting Paris Agreement goals is crucial for boosting MPA resilience and reaching international conservation targets, such as the post-2020 Convention on Biological Diversity framework, which aims to expand global MPA coverage to 30% by 2030.
SS071B Untangling the Role of Environmental Variability in the Resilience and Recovery of Marine Biota to Climate Change
Description
Time: 10:30 AM
Date: 6/6/2023
Room: Sala Menorca A