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Intraspecific facilitation in an intertidal foundation species plays fundamental role in promoting resistance to extreme climatic events
No full textAtmospheric and marine heatwaves are becoming more frequent, and severe, increasingly pushing organisms past their critical thermal limits and threatening the persistence of entire populations. Under greater levels of stress, positive species interactions (e.g. facilitation) are predicted to become increasingly important in promoting population and community-level resistance and resilience. While ecological interactions are important in driving the structure of marine benthic communities, the strength and nature of facilitative interactions under realistic stress conditions have rarely been empirically tested in these systems. Using an intertidal rocky shore dominated by the canopy-forming macroalga Fucus serratus as a model system, we conducted a novel manipulative field experiment to simulate a realistic three-day atmospheric heatwave and examined physiological responses of F. serratus fronds under both high and low-density treatments. We recorded a prominent facilitative interaction between canopy-forming plants and their sub-canopy counterparts, which almost completely ameliorated thermal stress. This positive interaction was evident at low density treatments and despite overlying air temperatures far exceeding previous estimates of the critical thermal maximum of F. serratus. However, despite sustained intraspecific facilitation, consecutive exposures to high air temperatures led to reduced resilience of canopy-forming plants. Our results have direct implications for assessing population-level vulnerability to current and future warming trends. We show 1) intraspecific facilitation will likely play a pivotal role in mediating stress, even at lower canopy densities, allowing the persistence of foundation species under extreme warming, and 2) consecutive exposures to stressful temperatures will reduce thermal resilience, jeopardizing positive ecological interactions. More broadly, incorporating facilitative interactions under extreme climatic events into predictions of responses to climate change will improve the accuracy of future vulnerability assessment
Metagenomics of the MAST-3 stramenopile, Incisomonas, and its associated microbiome reveals unexpected metabolic attributes and extensive nutrient dependencies
No full textProtists are polyphyletic singled-celled eukaryotes that underpin global ecosystem functioning, particularly in the oceans. Most remain uncultured, limiting investigation of their physiology and cell biology. MArine STramenopiles (MASTs) are heterotrophic protists that, although related to well-characterised photosynthetic diatoms and parasitic oomycetes, are poorly studied. The Nanomonadea (MAST-3) species Incisomonas marina has been maintained in co-culture with a bacterial consortium, offering opportunities to investigate the metabolic attributes and nutritional dependencies of the community. Employing a metagenomics approach, the 68 Mbp haploid genome of I. marina was retrieved to an estimated completeness of 93%, representing the most complete MAST genome so far. We also characterised the diversity of, and assembled genomes for, 23 co-cultured bacteria. Auxotrophy of I. marina for B vitamins (B1, B2, B6, B7 and B12), but not vitamins C, B3, B5 and B9 was predicted. Several bacteria also lacked complete B-vitamin biosynthesis pathways, suggesting that vitamins and/or their precursors are exchanged in the consortium. Moreover, I. marina lacked the ability to synthesise half the protein amino acids, although genes encoding the complete urea cycle were identified, like diatoms; this may play a role in recycling organic nitrogen compounds. Unexpectedly, we also identified the gene DSYB for dimethylsulphoniopropionate (DMSP) biosynthesis. Biosynthesis of this important stress-protectant and bacterial chemoattractant is typically found in photosynthetic eukaryotes and has not before been identified in heterotrophic stramenopiles. Together, our study reveals the metabolic attributes of a hitherto understudied organism, advancing knowledge of the evolution and adaptations of the stramenopiles and informing future culturing effort
The genome sequence of the amphioxus, Branchiostoma lanceolatum (Pallas, 1774)
No full textWe present a genome assembly from a specimen of Branchiostoma lanceolatum (Amphioxus; Chordata; Leptocardii; Amphioxiformes; Branchiostomatidae). The assembly contains two haplotypes with total lengths of 468.40 megabases and 465.81 megabases, respectively. Most of haplotype 1 (99.34%) is scaffolded into 19 chromosomal pseudomolecules. Haplotype 2 is a scaffold level assembly. The mitochondrial genome has also been assembled and is 15.14 kilobases in lengt
Cell death: A conserved cathepsin X controls algal cell fate
No full textThe discovery of a conserved protein (cathepsin X) dictating cell fate in diverse algae sheds light on the ancient evolutionary origins of programmed cell death in unicellular eukaryote
Copepod mortality due to short-term exposure to natural ultraviolet radiation at subtropical latitudes
No full textZooplankton, particularly copepods, are key components in aquatic food webs. However, the effects of ultraviolet (UV) radiation on copepods in marine systems, especially at tropical and subtropical latitudes, are not well understood. Incubations in UV and non-UV treatments during outdoor solar experiments at a subtropical latitude where copepods dominated the zooplankton community demonstrated that UV exposure led to 40%–50% higher mortality than in non-UV treatments after 4 h of exposure. In outdoor plankton migration tower experiments, most copepods avoided surface waters regardless of radiation treatment. While adaptations to avoid UV damage, such as the accumulation of photoprotective compounds, were observed in copepods, they were insufficient to fully mitigate UV-induced harm. Thus, surface avoidance is likely the primary adaptation employed by copepods and other zooplankton to evade UV exposure. This study expands upon existing UV research, which has largely focused on high-latitude and high-altitude ecosystems, suggesting that UV is a major environmental threat factor for low-latitude zooplankton. Hence, projected future climate-change related or geoengineering-driven increases in UV levels in subtropical and tropical systems may lead to higher mortality rates in zooplankton population
Seaweed exposure modulates Escherichia coli plasmid conjugation rate
No full textSeaweeds are a common and diverse component of coastal ecosystems and are known to be associated with Escherichia coli due to faecal pollution. As a biotic substrate, beach-cast seaweed may affect bacterial physiology and thereby horizontal gene transfer (HGT). Here, we test how the presence of three distinct senescing seaweed species affects E. coli plasmid conjugation. We allow the IncP plasmid pKJK5 to conjugate while supplying a substrate of Palmaria palmata (dulse), Ulva lactuca (sea lettuce) or Fucus serratus (serrated wrack). The three seaweed species induce distinct conjugative behaviours in E. coli: U. lactuca has no significant impact relative to a plastic control, the presence of F. serratus results in undetectable levels of conjugation and P. palmata promotes conjugation in a density-independent manner. This study highlights how biotic interactions can influence survival, HGT and antibiotic resistance in a human pathoge
Effects of zooplankton abundance on the spawning phenology of winter-spawning Downs herring (Clupea harengus)
No full textWe have investigated phenological shifts in autumn- and winter-spawning Atlantic herring (Clupea harengus) in the Eastern English Channel and the Southern North Sea (Downs component), in relation to temperature and the availability of potential zooplanktonic prey (Calanus finmarchicus, Calanus helgolandicus, Temora longicornis). A two-tiered approach building on the monthly distribution of commercial herring landings was developed, which consisted of, (1) calculating the timing and duration of spawning season based on estimated deviations from basic harmonic signals and, (2) analysing their inter-annual variations in relation to biotic (zooplankton abundance) and abiotic (temperature) environmental variables through time series analyses. The start, midpoint and ending of herring spawning season were increasingly delayed over the period 1999–2021, a process which was correlated with the abundance of Calanus finmarchicus. The resulting duration of spawning season slightly decreased. Direct effects of sea temperatures on any phenological metrics could not be clearly evidenced. Different ecological processes were likely involved in the start and ending of spawning season. Additional covariates (including size/age composition, the biotic and abiotic factors other than those examined in our study) could contribute to a better explanation of the phenological drift in Downs herring spawnin
Predicting photosynthesis–irradiance relationships from satellite remote‐sensing observations
Full text linkPhotosynthesis–irradiance (PI) relationships are important for phytoplankton ecology and quantifying carbon fixation rates in the environment. However, the parameters of PI relationships are typically unknown across space and time. Here we use machine learning, satellite remote‐sensing, and a database of in situ PI relationships to build models that predict the seasonal cycle of PI parameters as a function of satellite‐observed variables. Using only surface light, temperature, and chlorophyll, we achieve an R 2 of 58% for predicting photosynthesis rates at saturating light () and an R 2 of 78% for predicting the light saturation parameter (). Predictability is maximized when averaging environmental covariates over 30‐d () and 25‐d () timescales, indicating that environmental history and community turnover timescales are important for predicting in situ PI relationships. These results will help improve the parameterization of satellite‐based primary production models and quantify emergent environmental integration timescales in photosynthetic communities
Globalism, localism and blue food systems – How can cross-scale tensions be reduced? A production perspective from UK seafood stakeholders
No full text‘Blue foods’ are derived from aquatic species that are caught or cultivated and are amongst the most globally traded commodities. Growing emphasis is being placed on blue foods in future transitions to sustainable food systems. However, recent international events such as the Covid-19 pandemic, UK-EU ‘Brexit’, and Russia-Ukraine war have caused renewed interest in ideological debates between globalism and localism and associated cross-scale tensions. Here, we aim to provide further insight into cross-scale tensions in blue food systems through a literature review and UK-based seafood stakeholder workshop. From our literature review, the evidence for cross-scale tensions was linked to the following themes: economic efficiency versus social justice; food security and food sovereignty; sustainability and traceability. A stakeholder workshop revealed a need for international market actors to support improvements in the social and environmental practices of blue food producers. Fully traceable supply chains that enable the transfer of information across jurisdictions were also deemed desirable to provide greater assurance on product legality and provenance. Developing a blue foods strategy at a national level was suggested as a solution to potentially rebalance the influence of international markets, with the objective of rejuvenating re-localised blue food systems. To be successful, a blue foods strategy will require the alignment and integration of policies that impact on different industry subsector
How successive meteotsunami and storm activity disrupts saltmarsh vegetation
Full text linkMeteotsunami (meteorological tsunami) are globally occurring progressive shallow water waves with a period of
between 2 and 120 min which result from sudden pressure changes and wind stress due to moving atmospheric
systems. These waves are known to cause destruction to and loss of assets. Currently, there is no research into the
impact of meteotsunami on coastal ecosystems such as saltmarshes, despite the significant role saltmarsh play in
providing vital habitats for resident and migrating birds, natural flood defences and climate mitigation. As such
the restoration of saltmarshes has emerged as a pivotal focus within the UK Government’s environmental policy
framework.
This paper examines the impact of two meteotsunami events (2016 and 2021) on saltmarsh vegetation in the
southwestern UK. An assessment of the vegetation pre and post event was undertaken using high resolution
satellite imagery and the Normalised Difference Vegetation Index (NDVI). Results revealed that the 2016
meteotsunami exacted minimal vegetation change with a decrease in NDVI from 0.26 to 0.23 and a temporary
reduction in coverage of 40 %, suggesting a potential resilience to single episodic disturbances. In contrast, the
2021 event, compounded by multiple significant storms and additional meteotsunami, led to a decline in NDVI
values from 0.44 to 0.22 and a temporary reduction in vegetation coverage of 66 %. Both events indicated a
short-term disruption with a relatively rapid rebound (within one to three months). However, the longer-term
effects of such a disruption on the saltmarsh ecosystem need to be investigated further.
This comparative analysis underscores the complex interactions between meteotsunami, climatic phenomena,
and coastal vegetation dynamics, highlighting the necessity for ongoing monitoring and research to understand
the resilience mechanisms of such ecosystems in the face of increasing climatic variability and extreme weather
events