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Impacts of Climate Change on the Ascension Island Marine Protected Area and Its Ecosystem Services
Get PDFThis is the first projection of marine circulation and biogeochemistry for the Ascension Island Marine Protected Area (AIMPA). Marine Protected Areas are a key management tool used to safeguard biodiversity, but their efficacy is increasingly threatened by climate change. To assess an MPA's vulnerability to climate change and predict biological responses, we must first project how the local marine environment will
change. We present the projections of an ensemble from the Sixth Coupled Model Intercomparision Project. Relative to the recent past (2000–2010), the multi‐model means of the mid‐century (2040–2050) project that the AIMPA will become warmer (+0.9 to +1.2°C), more saline (+0.01 to +0.10), with a shallower mixed layer depth (− 1.3 to − 0.8 m), a weaker Atlantic Equatorial Undercurrent (AEU) (− 1.5 to − 0.4 Sv), more acidic (− 0.10 to − 0.07), with lower surface nutrient concentrations (− 0.023 to − 0.0141 mmol N m− 3 and − 0.013 to
− 0.009 mmol P m− 3), less chlorophyll (− 6 to − 3 µg m− 3
) and less primary production (− 0.31 to − 0.20 mol m− 2 yr− 1
). These changes are often more extreme in the scenarios with higher greenhouse gases emissions and more significant climate change. Using the multi‐model mean for two scenarios in the years 2090–2100, we assessed how five key ecosystem servicesin both the shallow subtidal and the pelagic zone were
likely to be impacted by climate change. Both low and high emission scenarios project significant changes to the
AIMPA, and it is likely that the provision of several ecosystem services will be negatively impacted.
Ascension Island is a small remote volcanic island in the equatorial
Atlantic Ocean. The seas around Ascension Island have been protected from commercial fishing since 2019. We
used the marine component of computer simulations of the Earth's climate to try to understand the future of the
Ascension Island Marine Protected Area (AIMPA). Over the next century, the AIMPA region will become
warmer, more saline, more acidic, less productive, and with lower nutrient and chlorophyll concentrations in the
surface waters. The most important current of the region, the Atlantic Equatorial Current, is also projected to
weaken in all scenarios. These changes are likely to negatively impact the ability of the AIMPA to provide
ecosystem services such as healthy ecosystems, fish stocks, the removal of carbon dioxide from the air, and
attract tourism. This work is important because it is the first projection of the climate around the AIMPA since it
was created, and it has allowed local policymakers to understand how the changing climate is likely to affect
their environment and ecosystem service
Evolutionary genomics of the emergence of brown algae as key components of coastal ecosystems
No full textBrown seaweeds are keystone species of coastal ecosystems, often forming extensive underwater forests, and are under considerable threat from climate change. In this study, analysis of multiple genomes has provided insights across the entire evolutionary history of this lineage, from initial emergence, through later diversification of the brown algal orders, down to microevolutionary events at the genus level. Emergence of the brown algal lineage was associated with a marked gain of new orthologous gene families, enhanced protein domain rearrangement, increased horizontal gene transfer events, and the acquisition of novel signaling molecules and key metabolic pathways, the latter notably related to biosynthesis of the alginate-based extracellular matrix, and halogen and phlorotannin biosynthesis. We show that brown algal genome diversification is tightly linked to phenotypic divergence, including changes in life cycle strategy and zoid flagellar structure. The study also showed that integration of large viral genomes has had a significant impact on brown algal genome content throughout the emergence of the lineag
Control of simulated ocean ecosystem indicators by biogeochemical observations
Get PDFTo protect marine ecosystems threatened by climate change and anthropic stressors, it is essential to operationally monitor ocean health indicators. These are metrics synthetizing multiple marine processes relevant to the users of operational services. Here we assess if selected ocean indicators simulated by operational models can be controlled (here meaning constrained effectively) by biogeochemical observations, by using a newly proposed methodological framework. The method consists in firstly screening the sensitivities of the indicators with respect to the initial conditions of the observable variables. These initial conditions are perturbed stochastically in Monte Carlo simulations of one-dimensional configurations of a multi-model ensemble. Then, the models are applied in three-dimensional ensemble assimilation experiments, where the reduction of the ensemble variance corroborates the controllability of the indicators by the observations. The method is applied for ten relevant ecosystem indicators (ranging from inorganic chemicals to plankton production), seven observation types (representing data from satellite and underwater platforms), and an ensemble of five biogeochemical models of different complexity, employed operationally by the European Copernicus Marine Service. We demonstrate that all the indicators are controlled by one or more types of observations. In particular, the indicators of phytoplankton phenology are controlled and improved by the merged observations from the surface ocean colour and chlorophyll profiles. Similar observations also control and reduce the uncertainty of the plankton community structure and production. However, the uncertainty of the trophic efficiency and POC increases when assimilating chlorophyll-a data, though observations were not available to assess whether that was due to a worsen model skill. We recommend that the assessment of controllability proposed here becomes a standard practice in designing operational monitoring, reanalysis and forecast systems, to ultimately provide the users of operational services with more precise estimates of ocean ecosystem indicators
Innovative and practical tools for monitoring and assessing biodiversity status and impacts of multiple human pressures in marine systems
Get PDFHuman activities at sea can produce pressures and cumulative effects in ecosystem components, that need to be monitored and assessed, in a cost-effective manner. Five Horizon European projects have joined forces to collaboratively increase our knowledge and skills to monitor and assess the ocean in an innovative way, assisting managers and
policy-makers in taking decisions to maintain sustainable activities at sea. Here we present and discuss the status of some methods revised during a summer school, aiming
at a better management of coasts and seas. We include novel methods to monitor the coastal and ocean waters (e.g. environmental DNA, drones, imaging and artificial
intelligence, climate modelling and spatial planning) and innovative tools to assess the status (e.g. cumulative impacts assessment, multiple pressures, Nested Environmental
status Assessment Tool (NEAT), ecosystem services assessment, or a new unifying approach). As a concluding remark, some of the most important challenges ahead is
assessing pros and cons of novel methods, comparing them with benchmark technologies, and integrating these into long standing time series for data continuity. This requires
transition periods and careful planning, which can be covered through an intense collaboration of current and future European projects on marine biodiversity and
ecosystem health
Non‐selective microbiota reduction after the elicitation of a seaweed's immune response
Get PDFPattern-triggered immunity (PTI) is an integral part of the innate immune system of many eukaryotic hosts, assisting in the defence against pathogen invasions. In plants and animals, PTI exerts a selective pressure on the microbiota that can alter community composition. However, the effect of PTI on the microbiota for non-model hosts, including seaweeds, remains unknown. Using quantitative polymerase chain reaction complemented with 16S rRNA gene and transcript amplicon sequencing, this study profiled the impact that PTI of the red seaweed Gracilaria gracilis has on its microbiota.
PTI elicitation with agar oligosaccharides resulted in a significant reduction in the number of bacteria (by >75% within 72 h after treatment). However, the PTI elicitation did not cause any significant difference in the community diversity or structure. These findings demonstrated that PTI can be nonselective, and this might help to maintain a stable microbiota by uniformly reducing bacterial loads
Remote sensing-based mangrove blue carbon assessment in the Asia-Pacific: A systematic review
Get PDFAccurate measuring, mapping, and monitoring of mangrove forests support the sustainable management of
mangrove blue carbon in the Asia-Pacific. Remote sensing coupled with modeling can efficiently and accurately
estimate mangrove blue carbon stocks at larger spatiotemporal extents. This study aimed to identify trends in
remote sensing/modeling employed in estimating mangrove blue carbon, attributes/variations in mangrove
carbon sequestration estimated using remote sensing, and to compile research gaps and opportunities, followed
by providing recommendations for future research. Using a systematic literature review approach, we reviewed
105 remote sensing-based peer-reviewed articles (1990 - June 2023). Despite their high mangrove extent, there
was a paucity of studies from Myanmar, Bangladesh, and Papua New Guinea. The most frequently used sensor
was Sentinel-2 MSI, accounting for 14.5 % of overall usage, followed by Landsat 8 OLI (11.5 %), ALOS-2
PALSAR-2 (7.3 %), ALOS PALSAR (7.2 %), Landsat 7 ETM+ (6.1 %), Sentinel-1 (6.7 %), Landsat 5 TM (5.5
%), SRTM DEM (5.5 %), and UAV-LiDAR (4.8 %). Although parametric methods like linear regression remain the
most widely used, machine learning regression models such as Random Forest (RF) and eXtreme Gradient Boost
(XGB) have become popular in recent years and have shown good accuracy. Among a variety of attributes
estimated, below-ground mangrove blue carbon and the valuation of carbon stock were less studied. The variation in carbon sequestration potential as a result of location, species, and forest type was widely studied. To
improve the accuracy of blue carbon measurements, standardized/coordinated and innovative methodologies
accompanied by credible information and actionable data should be carried out. Technical monitoring (every
2–5 years) enhanced by remote sensing can provide accurate and precise data for sustainable mangrove management while opening ventures for voluntary carbon markets to benefit the environment and local livelihood in developing countries in the Asia-Pacific region
Plant physiology: Plant stomata count on closure
No full textThe aperture of the stomatal pore is finely regulated by a range of external cues, and the underlying signalling events of this have been the subject of much investigation. A new study shows that elevation of cytosolic calcium is sufficient to induce stomatal closure and sheds light on the mechanisms underlying the regulation of stomatal apertur
Obituary: Eve Caroline Southward (née Judges) 1930–2023
No full textEve Caroline Southward (1930–2023) was a multi-talented scientist, motivated by her curiosity and love of nature. Since she was never paid as a scientist, Eve was an amateur, in the best sense of the word. She was highly proficient at transmission electron microscopy and made lasting contributions to polychaete taxonomy, morphology and ecology. Eve was internationally respected, especially for her studies on the Siboglinidae, mouthless and gutless tubeworms (formerly called Pogonophora) that are found worldwide in the deep-sea. She described how the siboglinids obtained nutrition from symbiotic, sulphur-oxidising bacteria and described similar symbiotic relationships in several bivalve species. Eve wrote over 140 scientific publications and described 56 new benthic species, 47 being mouthless and gutless ‘pogonophores’. Eve assisted her husband Alan Southward in starting broad-scale intertidal surveys around the British Isles and Northwest Europe. These surveys formed the foundation for the time-series, later continued by others, that allowed assessments of the influence of climatic fluctuations, using intertidal rocky shore biota as indicators. Eve contributed, with Alan, to what became a 50-year study describing the long-term effects on intertidal communities of the oil pollution and excessive dispersant use resulting from the Torrey Canyon oil spill in 1967. Eve also co-wrote the Linnaean Society Synopsis on Echinoderms of the British Isles and helped complete unpublished work by Alan Southward and others on barnacle taxonom
Spatiotemporal variability in the population demography of the golden kelp, Laminaria ochroleuca (Phaeophyceae), at its leading range edge
No full textOcean warming is driving poleward range shifts for many marine species. For foundation organisms that underpin the wider ecosystem, such as canopy-forming seaweeds, shifts in distributions or population demography can have widespread ecological consequences. The warm water kelp, Laminaria ochroleuca, is found towards its leading edge in Plymouth Sound (southwest England, UK), where it has proliferated in recent years, partially replacing the cool-water congeneric species, L. hyperborea, at some wave-sheltered locations. To determine how ecosystem dynamics have changed due to this substitution and to benchmark population structure, monthly surveys were conducted of L. ochroleuca populations at three sites over 10 months. Canopy-forming L. ochroleuca sporophytes were recorded in all months at all sites, in densities of up to ~8 individuals m‒2, indicating that this species is now a conspicuous space occupier within this ecosystem. Blade length, weight and fertility followed clear seasonal patterns peaking during late spring/early summer and rapidly declining in autumn/winter. Between-site variability was also observed, with greater densities, blade lengths/widths and standing stock biomass at the most wave-sheltered but tidally influenced site. The most abundant herbivore associated with L. ochroleuca was the blue rayed limpet, Patella pellucida, which was predominantly found in summer months and in greater abundance than reported values for other kelps in the region. Our survey wide estimates of carbon standing stock ranged from 408 ± 67 to 1006 ± 181 g C m‒2 across sites, with a regional mean of 615 g C m‒2, which was in line with previous estimates for the congeneric L. hyperborea at nearby sites. Overall, the most detailed demographic assessment of L. ochroleuca to date is provided, which allows for a greater understanding of its ecological role within the wider temperate ecosystem and serves as a robust baseline against which to detect future ecological change
How uncertain and observable are marine ecosystem indicators in shelf seas?
Get PDFOperational analysis and forecast products of shelf sea biogeochemistry often lack reliable information on
uncertainty. This is problematic, as good quality uncertainty information is both requested by the product end�users and essential for data assimilation. To address this problem we developed a quality-assessed ensemble
representation of many leading sources of uncertainty in a coupled marine physical-biogeochemical model
of the North-West European Shelf. Based on these ensembles we have estimated the uncertainty of several
marine ecosystem health indicators (MEHIs), acting as proxies for biological productivity, phytoplankton
community structure, trophic fluxes, deoxygenation, acidification and carbon export. We have also evaluated
how observable these MEHIs are from the most widely available observations of total chlorophyll (mostly from
the surface), highlighting those MEHIs and locations that need to be better monitored. Our results show that
the most uncertain and the least observable MEHI is the phytoplankton community composition, highlighting
the value of its observations (and their assimilation) particularly in the UK regional waters. We demonstrate
that daily operational estimates of the other MEHIs, produced by the Met Office, are fairly well constrained.
We also quantify how much MEHI uncertainties are reduced when one substantially coarsens the MEHI spatial
and temporal resolution, as in the global and/or climate applications