Climate “winners and losers” are organisms or groups of organisms expected to become more or less (respectively) abundant due to climate change, when climate responses are evaluated at a broad biological scale. -Omics approaches can be used to identify the genetic traits that confer climate resilience or susceptibility and their adaptation rate. Evidence from field studies and in situ observations may be leveraged to make isolated predictions, or to test forecasts made by ecosystem models about future microbial distributions. Likewise, culture manipulations that assess physiological adaptations to different physicochemical conditions can drive predictions of microbial community responses to changing aquatic environments. Whether or not organisms can be accurately and summarily predicted as climate “winners and losers”, either generally or regionally, is an open question with key implications for our language about future impacts of climate change on aquatic microorganisms and the ecosystems they shape. In this session, we invite talks describing evidence for climate resilience or sensitivity of microbial taxa from any aquatic environment. We particularly encourage talks from participants who link empirical and theoretical approaches, or specifically address the capacity of -omics approaches to predict climate impacts on microbial communities. We hope this session will inspire precise language about predicted climate impacts on key groups of aquatic microorganisms and promote dialogue about microbial groups experiencing recent climate impacts.
Lead Organizer: Arianna Krinos, Brown University (akrinos@vt.edu)
Co-organizers:
Christine Palermo, WHOI (christine.palermo@whoi.edu)
Margaret Mars Brisbin, University of South Florida (mmarsbrisbin@usf.edu)
Presentations
06:00 PM
Exploring the potential for zinc toxicity in low manganese Southern Ocean phytoplankton (8759)
Primary Presenter: Natalie Cohen, University of Georgia (cohen@uga.edu)
Marine diatoms have evolved complex traits and growth strategies to survive in the Southern Ocean where the bioactive trace metals iron (Fe) and manganese (Mn) are low in supply, yet metals such as zinc (Zn) can be in high concentrations. The same divalent metal transport system is thought to be used for Zn and Mn, which may result in excess Zn imported into cells and difficulty acclimating to low Mn concentrations. It is unclear whether Antarctic diatoms have adapted to this extreme chemical environment through the use of specialized transporters, efflux mechanisms, or Zn storage proteins compared to temperate phytoplankton counterparts. To address this, cultures are being grown in the lab with physiology (growth rates, cellular metal quotas) and transcriptomic experiments underway. Preliminary data suggests the temperate coccolithophore Geophyrocapsa huxleyi reaches Mn limitation under trace levels of Mn in seawater, while Southern Ocean diatoms have a reduced Mn requirement and can maintain higher growth levels relative to their maximum. Further, growth of the coccolithophore is suppressed under excess Zn levels, while Southern Ocean diatoms are unaffected. Transcriptomics will aid in identifying how these diatoms structure metabolic processes under Mn stress, which transporters are activated, and how excess Zn is managed in the Southern Ocean. Melting of sea ice and stratification with ocean warming is predicted to increase Fe supplies in the Southern Ocean, potentially expanding and exacerbating Mn stress. Such conditions may dictate species composition by favoring diatoms with evolved strategies for managing excess Zn and maximizing Mn specific uptake, while keeping high Mn-requiring phytoplankton such as coccolithophores out of the Antarctic zone.
06:00 PM
On thin ice- implications of shorter winters for the future of freshwater phytoplankton phenology and function (8982)
Primary Presenter: David Richardson, SUNY New Paltz (richardsond@newpaltz.edu)
Lakes around the world face rapidly warming temperatures coupled with shorter winters, which affects ice cover, and can alter phytoplankton dynamics. Increased phytoplankton blooms, including both cyanobacteria and eukaryotic taxa, threaten water quality, drinking water supplies, recreation, and energy flow through food webs. Despite the risks, current ecological theory and field sampling methods are not well equipped to predict alterations to phytoplankton structure and function over the entire year, including winter. We present a project overview for our new NSF Macrosystems grant, where our main objective is to study the transition from ice covered to ice free winters and assess the effects on freshwater ecosystem structure and function. Our study will compare lakes across a latitudinal gradient (Ontario to Florida) to span a variety of ice cover conditions, ranging from long ice cover to intermittent to ice-free. Our gradient also contains lakes with varying degrees of summer phytoplankton blooms. We focus on how ecosystem memory of winter conditions may result in altered spring and summer ecosystem conditions, including changes in cyanobacteria biomass,toxin production, and lake metabolism. We present plans for field surveys, experiments, and predictive modeling using high-frequency environmental sensors. We will also provide information and invite collaborators to participate in a global summer and winter lake sampling campaign commencing in summer 2025. This project assesses how changes in climate will ultimately affect basal ecosystem structure and function.
06:00 PM
PHOSPHORUS COMPETITION AMONG DIATOMS FROM CONTRASTING NUTRIENT REGIMES (9306)
Primary Presenter: Maxfield Palmer, Lamont-Doherty Earth Observatory (max.palmer54@gmail.com)
Diatoms are significant contributors to global carbon cycling, yet genera isolated from oligotrophic regions like the Sargasso Sea remain understudied relative to those from coastal environments. Oligotrophic regions are expected to expand in the future, requiring predictions of how different phytoplankton groups will respond to low nutrient conditions. We compared the physiological responses of a diatom isolated from low P Sargasso Sea (Chaetoceros sp.; P8E6) with a diatom isolated from a high P coastal environment (Thalassiosira pseudonana; CCMP1335). A series of biovolume-normalized competition studies were performed for this comparison in low P media. Cell abundance and growth rate data suggest that Chaetoceros sp. is not able to out-compete a coastal isolate at low P. A survey of transcriptomic data from these, and other, diatom isolates grown under low P identified a suite of commonly P-regulated transcripts, including transcripts for alkaline phosphatase and 5’ nucleotidase. These data indicate that Chaetoceros sp. and T. pseudonana exhibit similar responses to low P, challenging the hypothesis that diatoms from oligotrophic regions have distinct mechanisms to cope with P scarcity that might confer a competitive advantage. These findings highlight the need for additional experimental efforts to resolve underpinning adaptive responses and forecast the ecological implications for diatom communities in expanding oligotrophic regions.
06:00 PM
Kelpful interactions: microbial community assembly on Saccharina latissima under heat stress (9410)
Primary Presenter: Marcus Lin, McGill University (marcuslin@g.ucla.edu)
Kelp forests are highly productive ecosystems in temperate coastlines that are threatened by increasing extreme temperature events in the Anthropocene. These rising temperatures cause cellular damage to many cold-adapted kelp species that can result in widespread population mortality. Coated in dense, diverse microbial biofilms, kelp blades are hotspots of microbial interactions, yet the ecological dynamics governing the assembly and succession of these communities remain largely unknown. Here, we conducted mesocosm experiments with Atlantic sugar kelp (Saccharina latissima) to investigate how microbial communities assemble and take over as the kelp grows from the youngest (meristem) to the oldest tissue (distal) under heat stress. Applying novel continuous diversity measures to 16S rRNA gene sequencing at high temporal and spatial resolutions, we aimed to determine whether random environmental colonization or host selectivity drives the community composition of kelp biofilms. Subsequently, we analyzed how these microbial dynamics are altered in physiologically stressed kelp under rising temperatures. By elucidating microbial successional patterns on kelp, this work sheds light on how kelp may selectively filter their microbiomes and how heat stress may disrupt this potentially symbiotic relationship, impacting kelp health and resilience in a changing climate.
06:00 PM
SHRIMP BLACK GILL DISEASE IS CLIMATE DRIVEN BUT THE CATASTROPHIC DECLINE OF THE GEORGIA COMMERCIAL FISHERY IS LIKELY A RESULT OF SOCIOECONOMIC FACTORS (9048)
Primary Presenter: Marc Frischer, Skidaway Institute of Oceanography (Univ of GA) (frischer@uga.edu)
The performance of the penaeid shrimp fishery in the US Southeast has declined significantly over the past several decades. Declines have been coincident with the emergence of shrimp Black Gill (sBG) disease caused by the parasitic apostome ciliate Hyalophysa lynni. A causal relationship between sBG disease and commercial shrimp stocks has not, however, been demonstrated. The goal of this study was to analyze long-term commercial shrimp landings, fishing effort, sBG disease prevalence, and environmental parameters to determine whether sBG disease is responsible for the decline in the performance of the Georgia shrimp fishery. A derived variable representing the annual emergence time (ε) of sBG disease was significantly correlated with climate indices, winter water temperatures and the performance of the fishery, suggesting that climate associated warming has resulted in the earlier emergence of sBG disease and that microbial parasites of crustaceans may be “climate winners”. However, commercial shrimp landings normalized for fishing effort remain flat over time, suggesting that the effect of earlier sBG disease emergence on the fishery has been minimal, and that socioeconomic factors that depress prices and increase fishing costs are likely the larger contributors to the decline in the fishery.
06:00 PM
Mixotrophs dominate in surface waters of the subtropical North Atlantic: insights for a warming ocean (9045)
Primary Presenter: Thomas Trombetta, University of Amsterdam - IBED (t.trombetta@uva.nl)
With global warming, oligotrophic subtropical ocean biomes are predicted to expand in a near future. In these zones, marine mixotrophic protists are suspected to significantly contribute to primary production and bacterivory. Yet, their diversity and distribution are still poorly characterized, making it difficult to assess their role in the microbial food web in a warmer future. We sampled protistan community composition (18S rRNA gene) alongside a stratification (horizontal) and depth gradient (vertical; 5 – 125 m) across a 500 km North-South transect from the Azores into the sub-tropical gyre, in August 2022. Following taxonomic assignment of amplicon sequence variants, trophic modes were assigned to taxa in which these are known. We highlighted a clear trophic niche separation between mixotrophs, autotrophs and heterotrophs. Mixotrophs were found to be dominant in offshore surface waters, where nutrients are limited and light is plentiful, while autotrophs were more important in the deep chlorophyll maximum and heterotrophs in deeper waters. Among the mixotrophs, constitutive mixotrophs were by far the most abundant and increased in relative abundance in offshore surface waters, highlighting their ubiquity but also their relevance in the oligotrophic ocean. Interaction network analysis revealed that they play a crucial role in the microbial food web in the stratified layers. With global warming and the expansion of oligotrophic conditions, we expect the relevance of mixotrophs for food web functioning and biogeochemical processes to increase in future oceans.
06:00 PM
ROLE OF PARTICLE-ASSOCIATED BACTERIA IN AGGREGATE FORMATION IN THE CURRENT AND FUTURE OCEAN (9442)
Primary Presenter: Britni Livar, Arizona State University (blivar@asu.edu)
The formation of aggregates is an important part of the biological carbon pump as carbon is exported to depth. These particles are composed of cells, minerals, and other sources of organic carbon that can be held together by transparent exopolymeric particles (TEP) acting as a glue-like matrix. Due to anthropogenic impacts, the concentration of carbon dioxide in the atmosphere is steadily increasing, causing an increase in ocean temperature and acidity, and it is essential to understand how carbon export by the biological carbon pump is impacted by future ocean conditions. Using mesocosms and roller tank experiments, we investigated the aggregation potential of natural seawater planktonic communities in the summer in the Sargasso Sea under current and future ocean conditions. Future ocean conditions were simulated at 30 degrees Celsius and 7.9 pH, while ambient conditions were simulated at 27 degrees Celsius and 8.1 pH. Roller tank experiments carried out in both conditions resulted in visible macroaggregates with a clay addition. Significantly more aggregates formed under ambient conditions, but there was no significant difference in aggregate diameter between treatments. We will present 16S sequencing analyses of size-fractionated aggregates to understand how the different conditions influenced microbial communities and show how TEP concentrations differed in the treatments. Our findings expand our understanding of how anthropogenic stressors, including ocean acidification and ocean warming, impact aggregation and carbon sequestration in the ocean.
SS19P - Climate “winners and losers”: predicting and assessing microbial responses to climate change
Description
Time: 6:00 PM
Date: 29/3/2025
Room: Exhibit Hall A