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More realistic plankton simulation models will improve projections of ocean ecosystem responses to global change
Full text linkPlankton models form the core of marine ecosystem simulators, with uses from regional resource and ecosystem management to climate change projections. In this Perspective, we suggest that stronger alignment of models with empirical knowledge about plankton physiology, diversity and trophic roles will improve model utility and the reliability of their outputs regarding biodiversity, ecophysiology, trophic dynamics and biogeochemistry. We recommend key steps to resolve the disconnect between empirical research and simulation models accounting for well-established plankton processes with an aim to increase the utility of such models for applied uses. A central challenge is characterizing the complexity of plankton diversity and activity in ways that are amenable to model incorporation. We argue that experts in empirical science are best placed to advise the development of next-generation models to address these challenges, and we propose a series of actions to achieve that engagement, including involvement of these experts in the design and exploitation of plankton digital twins
Sargassum Biomass Movement and Proliferation in the Eastern Tropical Atlantic
Full text linkSince 2011, pelagic sargassum blooms (S. fluitans and S. natans) have impacted coastal communities, aquaculture, tourism, and biodiversity across the Tropical Atlantic region. Whilst the initial event is generally attributed to an anomalous North Atlantic Oscillation (2009–2010), the drivers of sargassum movement and proliferation remain unclear. This research gap is particularly evident in West Africa, where annual and seasonal sargassum variability is under-researched, and a lack of consensus exists on seasonal and annual trends. This paper addresses these gaps by (1) providing a first attempt at characterising the seasonal and annual trends of sargassum biomass in the Eastern Tropical Atlantic, through using satellite imagery to create a time-series for 2011–2022; and (2) exploring the hypothetical drivers of movement and proliferation of sargassum for this area, through assessing its co-variation with potential drivers including atmospheric, oceanic, and policy, establishing a historical timeline of events. The time-series analysis reveals an annual biomass peak in September and a second peak between March and May. The exploration of potential drivers reveals that alongside sea surface temperature there are multiple factors that could be influencing sargassum biomass, and that further research is necessary to clarify primary and secondary drivers. The results contribute to understanding drivers, impacts, and predictions of sargassum blooms in the Eastern Tropical Atlantic. We anticipate that our findings will enable sargassum-affected areas to better anticipate the size and timing of sargassum events in West Africa and offer researchers a new perspective on possible drivers of proliferation within the wider Tropical Atlantic region
Assessing, monitoring and mitigating the effects of offshore wind farms on biodiversity
No full textOffshore wind farms (OWFs) are integral to the global shift towards renewable energy, yet they introduce complex challenges for marine biodiversity. OWF development affects a range of species — including fish, invertebrates, seabirds and marine mammals — through noise pollution, habitat alteration, physical barriers and potential entanglement. Conversely, turbine structures can act as artificial reefs and fish refuges, enhancing local biodiversity. This Review synthesizes current knowledge of OWF impacts across their life cycle — from construction to decommissioning — highlighting both direct and indirect ecological effects, including food web changes and displacement of fisheries. The Review discusses assessment, monitoring and mitigation strategies, and emphasizes the need for more coordinated international approaches, particularly in the areas of data sharing, cumulative impact assessments and long-term ecological monitoring. Differences in governance, regulation, data collection and mitigation strategies across countries or regions lead to varying biodiversity outcomes at OWFs. We outline priority steps that could be taken to improve assessment and monitoring across regional and international scales, including the use of emerging technologies, adaptive management, the development of more sophisticated models and decision-support tools, and the establishment of regionally tailored ecosystem monitoring programmes to better understand the impacts of OWF energy developments on biodiversity
A novel cyanobacteria occurrence index derived from optical water types in a tropical lake
Full text linkCyanobacteria blooms are a threat to water quality of lakes and reservoirs worldwide, requiring scalable
monitoring solutions. Existing approaches for remote sensing of cyanobacteria focus on quantifying (accessory)
photosynthetic pigment to map surface accumulations. These approaches have proven challenging to validate
against in situ observations, limiting uptake in water quality management. Optical Water Types (OWTs) have
been used in inland and ocean waters to dynamically select suitable algorithms over optical gradients, thereby
helping to limit out-of-scope application of individual algorithms. Here, we present a proof-of-concept study in
Winam Gulf, Lake Victoria, extending an existing OWT framework using a hybrid approach combining in situ and
satellite-derived water types. This extended OWT set of 25 water types, obtained from K-means clustering > 18
million Sentinel-3 Ocean and Land Colour Instrument (OLCI) spectra, was found to better capture the optical
diversity of cyanobacteria bloom phases compared to the original OWT set. We translate this framework into a
novel Cyanobacteria Occurrence Index (COI) by assigning weights to key optical features observed in the OWT
set, such as phycocyanin absorption and surface accumulation. COI was strongly correlated with established
algorithms for chlorophyll-a (Maximum Peak Height; r = 0.9) and phycocyanin (Simis07; r = 0.84), while
potentially capturing various bloom phases in optically mixed conditions. We demonstrate how COI could be
mapped onto a three-category risk classification to facilitate communication of cyanobacteria occurrence risk.
Initial tests across diverse waterbodies suggest potential for wider application, though further validation across
different environmental conditions is needed. This work provides a foundation for improved cyanobacteria
monitoring in optically complex waters, particularly where conventional sampling approaches face limitation
Insights into the origins of calcification from coccolithophore life cycles
No full textMarine phytoplankton play critical roles in global biogeochemical cycles, so it is remarkable that fundamental aspects of their biology remain poorly understood. One striking example is our incomplete understanding of life-cycle histories in many phytoplankton groups. The coccolithophores, with their characteristic cell covering of calcium carbonate plates (coccoliths), represent a lineage for which much remains to be learned about their life cycle. Most studies have focused on the heavily calcified diploid phase. However, coccolithophores can also exist in a haploid phase that is lightly calcified and often motile. Both phases can persist in the environment and reproduce asexually, representing a haplo-diplontic life cycle. The comparative biology of these life-cycle phases and the environmental factors that trigger switching between them remain poorly understood, representing a significant knowledge gap in coccolithophore biology, particularly when predicting their response to future environmental change (Frada et al., 2018
Ocean Acidification: Another Planetary Boundary Crossed
Full text linkOcean acidification has been identified in the Planetary Boundary Framework as a planetary process approaching a boundary that could lead to unacceptable environmental change. Using revised estimates of pre‐industrial aragonite saturation state, state‐of‐the‐art data‐model products, including uncertainties and assessing impact on ecological indicators, we improve upon the ocean acidification planetary boundary assessment and demonstrate that by 2020, the average global ocean conditions had already crossed into the uncertainty range of the ocean acidification boundary. This analysis was further extended to the subsurface ocean, revealing that up to 60% of the global subsurface ocean (down to 200 m) had crossed that boundary, compared to over 40% of the global surface ocean. These changes result in significant declines in suitable habitats for important calcifying species, including 43% reduction in habitat for tropical and subtropical coral reefs, up to 61% for polar pteropods, and 13% for coastal bivalves. By including these additional considerations, we suggest a revised boundary of 10% reduction from pre‐industrial conditions more adequately prevents risk to marine ecosystems and their services; a benchmark which was surpassed by year 2000 across the entire surface ocean
Taxonomic uncertainty in North Atlantic and Mediterranean zooplankton limits species-level monitoring accuracy
Full text linkTaxonomic discussions often permeate the broader scientific community slowly, yet they may hold more relevance than typically assumed. In many zooplankton groups, identification issues arise from cryptic species complexes, increasingly revealed by molecular approaches, and from groups with high morphological similarity. These challenges can lead to substantial uncertainties in species-level identification, questioning whether the expected species are truly covered and whether those sharing names across ecosystems are indeed distinct entities. This review provides a condensed overview on identification challenges of key species in the ICES zooplankton time series from the North Atlantic and adjacent seas. Examples are given across all relevant groups, including copepods, gelatinous plankton, and meroplanktonic larvae. The high prevalence of challenging species complexes underscores the need to further explore the implications of an accurate species assignment for understanding what defines a species’ role in an ecosystem. This review highlights the dynamic nature of taxonomy, with species being split and cryptic species eventually becoming morphologically distinguishable. It provides examples showing that relying solely on molecular methods without deep taxonomic expertise poses significant risks. It also aims to serve as a starting point for delving deeper into the taxonomy of the ICES zooplankton time series
The Western Channel Observatory Automated Plankton Imaging and Classification System
Full text linkMarine plankton are an important and diverse group of organisms that make up the lower trophic levels of the marine food web. They play several critical roles in the ocean that have direct or indirect societal benefits, including supporting food security, oxygen production, and carbon sequestration via the biological carbon pump. Plymouth Marine Laboratory (PML) has been making weekly measurements of zooplankton and phytoplankton at Western Channel Observatory (WCO) Station L4 (50°15'N, 4°13'W) since 1988 and 1992, respectively, using traditional ship-based sampling and light microscopy techniques. Thus, Station L4 has become one of the longest-running, continuous plankton time series in the world and a key marine biodiversity reference site for studies into both short- and long-term environmental changes
Insights into silicon cycling from ice sheet to coastal ocean from isotope geochemistry
Full text linkAbstract
The polar regions are biologically productive and play a critical role in regional and global biogeochemical cycling. A key nutrient is dissolved silicon, required for the growth of siliceous phytoplankton, diatoms, which form an important component of polar ecosystems. Glacial weathering is thought to be an important dissolved silicon source to coastal waters, especially critical in regions experiencing seasonal silicon limitation of diatom growth. However, complex physical and biogeochemical interactions in fjords and coastal regions modulate the downstream supply of dissolved and particulate nutrients, including silicon. Here, we review the biogeochemical complexities of glaciated margins and the insights into this system that silicon isotope geochemistry offer. We show that stable and radioisotopic measurements and biogeochemical numerical modelling provide a quantitative mechanistic understanding of subglacial silica mobilisation and its cycling across the land-ocean continuum. Subglacial weathering produces isotopically light amorphous silica, which dissolves in seawater to release dissolved silicon. Our findings show that isotopically light, detrital silica, likely containing glacial material, reaches the ocean and there could support a substantial proportion of diatom productivity, especially in the Arctic. Outstanding questions about silicon cycling in these crucial environments will be addressed through novel and cross-discipline approaches that overcome traditionally viewed ecosystem boundaries
Ecotoxicological effects of sunscreen derived organic and inorganic UV filters on marine organisms: A critical review
Full text linkSunscreens are topical personal care products that provide protection against the sun's ultraviolet A (UVA) and
ultraviolet B (UVB) radiation. Ultraviolet (UV) filters are compounds added to sunscreens to block, absorb, or
reflect the sun's UV rays, but are of major emerging concern due to their widespread use and global distribution.
They pose a significant risk to marine organisms owing to their chemical properties, including high lipophilicity
which increases their bioavailability. The present review identifies and summarises the factors that contribute to
UV filter pollution, their sources, pathways, and effects on marine organisms. We identify and evaluate the
current knowledge base and gaps pertaining to their effects. Here, we retrieved 111 peer-reviewed articles from
four academic search engines between January and October 2024 with the topic search relating to UV filters,
sunscreen and ecotoxicology. Most publications (60 %) focused on the biological effects of organic UV filters,
with oxybenzone (benzophenone-3) being the most studied (57 %). Fewer publications assessed the biological
effects of inorganic UV filters (40 %). Throughout all search results, the most commonly tested species were in
the class of bivalvia (24 %) and oxidative stress based assays were the most popular (organic studies 40 %,
inorganic studies, 39 %). To enhance understanding, future research should explore a broader range of organisms
and life stages, considering dietary uptake and realistic environmental conditions, including the use of UV
lighting in laboratory settings