Instituto Español de Oceanografía

The planktonic marine diatom genus Pseudo-nitzschia is synonymous with the neurotoxin domoic acid (DA), which causes the syndrome amnesic shellfish poisoning (ASP). DA can bioaccumulate in shellfish during blooms of specific, toxin-producing Pseudo-nitzschia, harming wildlife and human health. Phenotypic discrimination of variants requires electron microscopic observation of the frustule, a process too time-consuming for routine monitoring, which invariably uses light microscopy. This process is less specific and has poor correlation with accumulation of DA in shellfish. The assay outlined here targets the ribosomal DNA gene, providing species resolution of Pseudo-nitzschia. It combines recombinase polymerase amplification (RPA) with nanopore sequencing and is effective on almost all known Pseudo-nitzschia species. It provides preliminary, real-time indication of environmental species composition, and further bioinformatic processing confirms results. Validation experiments correctly identified 13 reference cultures, with sufficient sensitivity (2500 cells l-1). Two environmental case studies highlighted efficacy on complex natural Pseudo-nitzschia blooms, including detection of low abundance species. The first study consisted of 37 samples collected from Scottish waters between May 2022 and August 2023, which identified 13 species. The second consisted of 10 samples from Aotearoa (New Zealand) collected February 2025, which found 17 species. Both studies identified species previously undetected in the regions. Statistical analysis of complementary toxin data from Scotland, although limited, highlighted that relative abundance of toxic species was a better predictor of toxic events than genus level cell counts. The RPA assay was also adapted to a lateral flow dipstick, providing a rapid screening tool for toxic Pseudo-nitzschia seriata and Pseudo-nitzschia australis.

In metacommunity theory, which has primarily addressed horizontal processes, vertical connectivity has received little attention despite being a primary driver of biodiversity in spatially structured environments. This conceptual blind spot limits our

Abstract Subsurface and nearly neutrally-buoyant floats can be stable, well-behaved platforms for measuring ocean dynamics in the near-surface wave zone. Here, we measure and model the wave-induced tilt of one such platform. We use data from Lagrangian floats carrying Nortek Signature1000 acoustic Doppler current profilers with Attitude and Heading Reference System (AHRS). We analyze carefully chosen data segments where the wave-induced tilts are measurable yet small and the float does not rotate significantly. We adopt a two-dimensional, depth-downwave coordinate system and assume small tilts and linear surface wave dynamics. By combining the constraints due to geometry, a wave-following float, and wave dynamics, we link measurements of both linear and angular acceleration to measure the tilts to an accuracy of a few tenths of a degree and simultaneously show that the data is consistent with the analysis assumptions. This analysis is further vetted by swinging the AHRS on pendulums in the laboratory. The same tests disturbingly indicate that the AHRS attitude readings can have large errors for tilts larger than a few degrees. The wave-induced tilt of the floats is predicted to an accuracy of about 10% from the wave properties by a 3-parameter linear semi-empirical model calibrated with field data in which waves force tilt through their horizontal acceleration and through their strain exerting torques on the float. These floats are a somewhat underdamped oscillator (Quality Factor=3, resonance at 3 second period) and will exhibit a decaying oscillation of a few cycles when perturbed.

Rocky coastlines of newly formed lava deltas change rapidly after their emplacement if they are exposed to energetic waves and where they are internally weak. Such rapid changes can be studied in detail using time-lapse remote sensing data from recent eruptions. Two lava deltas were created during the 2021 La Palma eruption. We use 0.5-m-resolution Pléiades satellite images to characterize their evolution on daily and monthly intervals over 14 months, providing young lava-coastline change data of high temporal resolution for the first time. Coasts of these two deltas are classified into pocket beaches and rock promontories. The pocket beaches were formed from eroded volcanic materials. Fluctuations in their positions correlate strongly with tidal water level. Within the first 39 days, annualised coastal retreat rates of the promontories reached 712 m/yr, the fastest retreat rates found so far in young lava coasts, before decreasing with time. We interpret this change as due to the presence of friable materials on the lava fronts (e.g., clinker), which were easily eroded by waves initially, in contrast with later slow retreat due to more resistant lithologies within lava flow interiors. Slowed coastal retreat may also be due to attenuation of waves crossing a growing submarine platform in front of the deltas and protection from clastic materials formed by collapsed sea cliffs. In addition, the coastline of the northern delta became more crenelated in plan-view and retreated quickly. That retreat followed a similar systematic slowing found in other new rocky coasts formed by historical eruptions. In contrast, coastline of the southerly delta was more rounded and changed minimally. These deltas experienced two markedly different histories despite lying less than ~1 km apart, which can be explained by different patterns of lava flow emplacement and internal structure.

The increasing presence of abandoned, lost, or discarded fishing gear (ALDFG) on the seafloor is a major source of microplastics (MPs) pollution in coastal ecosystems. This study assessed the concentration, morphology, and chemical composition of MPs in surface sediments collected from Alicante and Benidorm, in the Valencian Community, eastern coast of Spain, Mediterranean Sea. Impacted sites with fishing nets were compared to control sites without nets. Two analytical techniques were used for polymer identification, depending on particle size: micro-Fourier Transform Infrared Spectroscopy (µFTIR) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (FTIR-ATR). The results showed significantly higher MPs concentrations in sites affected by ALDFG. The findings highlight a clear link between the presence of fishing nets and MPs accumulation in sediments. This underlines the urgent need for mitigation strategies and recovery of discarded fishing gear. This study addresses a gap in the literature regarding MPs contamination on rocky coastal substrates and calls for further research to assess the long-term ecotoxicological impacts on marine ecosystems.

Abstract Oceanic stratification plays a key role in climate by modulating the ocean's resistance to be mixed vertically. However, the climatic variability of stratification remains little documented beyond the deepest reach of winter mixing. Here, we address this gap by performing a global investigation of the spatio‐temporal variability of stratification from the surface to the main pycnocline, using 20 years (2003–2022) of data from the Argo float array. Both near‐surface and main pycnocline stratification are found to exhibit spatially structured, vertically coherent, global‐scale variations on seasonal‐to‐decadal time scales, suggesting that stratification at both levels are rapidly‐evolving and responsive components of the climate system. Variability in stratification is organized into well‐defined patterns that replicate the spatial footprints and time scales of major climate modes, pointing to these modes of variability as important drivers of stratification changes. Our diagnosed patterns and forcings of stratification variability provide a benchmark for advancing the climate models used to understand and predict the ongoing climate change.

Maternal effects play a fundamental role in shaping early larval growth and survival in marine fishes. This study explores the relationship between maternal trophic ecology and larval growth in bluefin tunas, with a focus on Southern Bluefin Tuna (SBT) and an expanded dataset from multiple Atlantic Bluefin Tuna (ABT) populations incorporated into the General Bluefin Model (GBM). Daily growth and stable isotopes (δ 15 N and δ 13 C) were obtained from 80 pre-flexion SBT larvae and 355 pre-flexion larvae from the GBM dataset. Results revealed a significant negative linear trend between larval age and δ 15 N values, consistent with the gradual attenuation of maternally inherited isotopic signatures during development. Faster growing larvae showed significantly lower δ 15 N and δ 13 C values, indicating that maternal trophic behaviour and prey sources critically influence larval growth potential. Maternal isotopic niche breadth, inferred from larval isotope data, was markedly narrower in groups with optimal larval growth, suggesting that specialized (stenophagous) maternal feeding strategies promote enhanced offspring performance. These patterns were observed consistently in two bluefin species across seven different populations, despite geographic and temporal variability, highlighting a robust ecological link between maternal foraging behaviour and larval development. From these findings, we introduce the hypothesis of an Optimal Maternal Feeding Isotopic Niche, representing a constrained isotopic range associated with increased larval growth and survival. This framework advances our understanding of the influence of maternal trophic ecology on offspring fitness and offers valuable insights for the conservation and management of highly migratory pelagic species with complex reproductive strategies.

This systematic review examines the use of the mizer R package, a tool for multi-species size-spectrum modeling of marine ecosystems, over the past decade. We analyzed 43 publications, including peer-reviewed articles and academic theses, to highlight its contributions, strengths and limitations across various research domains. We grouped studies into five categories: fisheries management and policy, ecosystem dynamics and species interactions, methodological advances, climate change projections, and broad-scale ecological studies. Geographically, the majority of studies were concentrated in marine ecosystems, particularly in the North Sea and Haizhou Bay, China. Our visualizations, including maps, timelines, Sankey diagrams, and a scientific collaboration network, revealed strong international collaboration, with the UK, Australia, and the USA emerging as central hubs in the global research network. The mizer package has evolved through various extensions such as therMizer, MizerShelf and MizerEvo , broadening its application in studying climate impacts and eco-evolutionary dynamics. Overall, mizer has proven to be a valuable tool in advancing our understanding of aquatic ecosystems and informing sustainable management practices. Despite its widespread use in theoretical and exploratory studies, direct applications of mizer-derived strategies in real-world fisheries management remain limited, underscoring the challenges of integrating complex models into decision-making frameworks. We identify several opportunities to enhance mizer’s practical relevance, including the development of validation datasets and benchmarking protocols, comparative evaluation with other ecosystem models, structured sensitivity and uncertainty analyses, and incorporation of socio-environmental feedbacks. We also highlight key technical limitations, such as the absence of automated parameter optimization and the reliance on equilibrium-based model structure, which currently constrain its use in dynamic or data-limited contexts. Addressing these challenges will be critical for advancing the integration of size-spectrum modeling into ecosystem-based management and policy.