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Combined crystallographic study of king scallop (Pecten maximus) shells using SEM, EBSD and Raman spectroscopy
No full textThe shells of Pecten maximus (king scallop) are composed primarily of polycrystalline calcitic calcium carbonate, with a crucial aragonitic prismatic myostracum layer that facilitates soft tissue attachment and contributes to mechanical strength. Despite its importance, the impact of environmental stressors, such as metal contamination, on the myostracum remains underexplored. Hence, this study's main goal was to shed light on the microstructure and crystallography of king scallop shells, particularly the myostracum region, using a combination of scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) analysis, and Raman spectroscopy. This approach was chosen to develop new protocols that integrate imaging techniques for a systematic analysis of pollution effects on shell growth and properties. Such an understanding is crucial for assessing the impact of environmental contamination on shell structure and composition. We compared samples from a metal contaminated site (Laxey) with those from non-contaminated site (Bradda) around the Isle of Man, to determine which structural and crystallographic information is detectable using the selected microscopy and spectroscopy techniques. SEM imaging showed a similar myostracum organization in specimens from both sites, with elongated, oriented grains. However, the non-contaminated site shell had more regular and elongated grains, while the shell from the contaminated site exhibited a broader grain size distribution, visible via electron channeling contrast and backscattered electron detection. EBSD analysis confirmed that both types exhibited well-crystallized aragonite in the myostracum, with slight differences in grain orientation and grain size with co-orientation indicating a marginal reduction in crystallographic alignment in the contaminated site shell. Raman maps reveal shifts in peak positions, indicating crystallite strain and differences in grain size. These variations may be related to a biological adaptation aimed at toughening the shell, but pollution could disrupt this crystallization process, weakening the shell. The combination of these techniques can advance our understanding of the microstructural alterations caused by metal contamination, highlighting its potential impact on the structural integrity of the shell. This study is a proof of principle study showing how a combination of different established imaging techniques can provide complementary and novel insights into the structure and composition of the king scallop myostracum. This systematic approach aims to develop new evaluation approaches for the study of the effects of environmental pollutants on the crystallography and microstructure of marine bivalve shells and hence their resilienc
Can the emerging European seaweed industry contribute to climate change mitigation by enhancing carbon sequestration?
No full textBlue carbon habitats, which exhibit high rates of natural carbon sequestration, typically refer to salt marshes, seagrass meadows, and mangrove forests. Recent studies, however, have argued for the inclusion of seaweed-dominated habitats, like kelp forests, into blue carbon frameworks. Farmed seaweed may also function as a blue carbon habitat, with large-scale seaweed aquaculture suggested as a climate change mitigation strategy, but the evidence base remains limited. Here, existing knowledge on the mechanisms influencing carbon uptake, release, transport, and storage from kelp farms was synthesised, and a literature review was conducted to quantify associated rates of carbon sequestration. We identified strong geographical and methodological biases in the literature, with the majority of studies conducted in Asia and focusing on primary production rates as a proxy for carbon sequestration potential. Estimates of carbon release and storage rates were highly variable across locations, species, and approaches, and a scarcity of research on dissolved organic carbon, sedimentary carbon, and net ecosystem productivity was identified. Although the European kelp farming industry is in its infancy, it is predicted to expand to meet increasing demand for seaweed biomass. This is incentivised by perceived associated ecosystem service benefits such as enhanced carbon sequestration. However, multiple factors including environmental concerns, a lack of quantitative evidence, operational challenges, and regulatory complexities hinder industry expansion. Based on both the synthesised empirical evidence and an examination of key barriers and knowledge gaps, we identify future challenges and research priorities needed to assess the role of seaweed farming for climate change mitigatio
The disruption of a symbiotic sea anemone by light pollution: Non-linear effects on zooxanthellae and molecular indicators
Full text linkArtificial Light at Night (ALAN) is a pervasive stressor that may affect coastal organisms, particularly sessile forms associated with photosynthetic symbionts. We examined the effects of ALAN upon the symbiotic snakelocks anemone (Anemonia viridis)’s relationship with photosynthetic zooxanthellae, as well as molecular indicators of oxidative stress and metabolism. Anemones were exposed to natural daylight/night or either mild or strong ALAN intensities for four weeks, before quantifying zooxanthellae, superoxide dismutase (SOD) enzymes, and respiration rates. In comparison to natural conditions, anemones exposed to ALAN showed significantly higher and lower zooxanthellae counts, under mild and strong ALAN, respectively. In turn, SOD concentrations were lower and much higher when exposed to mild and strong ALAN, respectively, with no change in respiration rates. Concurrent bleaching suggests that ALAN is harmful to this, and possibly other species associated with symbiotic microalgae. And while we didn't measure heat stress, such bleaching may potentially act synergistically with other larger-scale forms of bleaching associated with rising ocean temperatures
Investigating temperature influences on shell growth and microstructural variations in Bay scallops: Insights from multiscale microscopy
No full textScallops (order Pectinida) are well-known for robust and beautiful calcitic shells that protect them from external impacts and predators. Scallops respond to environmental conditions, including water temperature, salinity, and food supply, which are reflected in the shell growth rates and patterning. The Bay scallop (Argopecten irradians) is a species of high ecological and aquacultural value in North America, and its habitat may expand towards higher latitudes with inevitable global warming. To investigate the effect of water temperature on the accretion rate and the polycrystalline microstructure of the Bay scallop shell, we conducted a controlled growth experiment on juveniles, 4 weeks following their larval metamorphosis. Approximately 400 individuals, collected from a hatchery 4 weeks after metamorphosis, were then reared in reconstituted seawater for 9 weeks at 23 °C and 26 °C. At 7-, 9-, 11-, and 13-weeks post-metamorphosis, calcein was added to the water for 7 hours for fluorescent staining, and then equal batches of scallops were collected and fixed. Morphologic characterization of bay scallop shells included micro-computed X-ray tomography for 3D measurements to measure shell thickness, and fluorescent light microscopy for accretion rate assessment. We used mechanical testing of complete shells in compression to assess their stiffness, strength and toughness. Microstructural analysis of the shells included scanning electron microscopy and crystallographic analysis by electron backscattered diffraction. The scallops reared in warmer water exhibited a faster growth rate with shells showing higher calcite grain misorientation, but no difference in relative shell thickness, or shell mechanical properties. This study may help us to understand the multifarious implications of climate chang
Turning riprap into reefs: Integrating oyster shells into shoreline armouring
No full textBoulder seawalls constructed with granite riprap for shoreline armouring lack habitat complexity, leading to lower marine biodiversity than natural rocky shores. Baskets of live oysters and cured oyster shells, and strings of cured shells laid on concrete blocks were installed on ripraps in Hong Kong, China with an aim to enhance biodiversity and ecosystem functioning towards that of a natural rocky shore. Inhabiting taxa were monitored for at least 18 months and biofiltration capacity of the emerging community was determined ex-situ. Despite high mortality of the live oysters, the baskets and shell reefs developed consistently greater biodiversity than control riprap, culminating in a mean 3.8 (±0.28, 95 % C.I.) times higher across sites. The baskets and shell reefs harboured suspension feeders, herbivores and carnivores generally absent from control riprap, demonstrating the potential for enhancing ecosystem functioning. Overall, baskets and shell reefs increased biodiversity through increased microhabitat availability for epibiota on riprap
Adjusting the management of the Antarctic krill fishery to meet the challenges of the 21st century
Full text linkAntarctic krill ( Euphausia superba ) is the central prey species in the Southern Ocean food web, supporting the largest and fastest-growing fishery in the region, managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Climate change is threatening krill populations and their predators, while current catch limits do not take into account climate variability or krill population dynamics. In 2024, CCAMLR was unable to renew its spatial catch limits, highlighting the urgent need for improved management of the krill fishery to prevent any harm to the Southern Ocean ecosystem. To address this, we propose a management framework that integrates variability in krill recruitment and key pathways between spawning and nursery areas—a krill stock hypothesis—to inform decisions on catch limits and conservation measures. Implementing this approach will require targeted data collection, which we propose can be achieved through a multisector collaborative network that combines traditional and new technologies, including the use of fishing vessels as data collection platforms. We use case studies to demonstrate how fisheries can contribute to data collection while promoting sustainable management. A major challenge in this effort is securing long-term funding for data collection, which is critical for managing climate-sensitive populations of high commercial interest. We therefore recommend using the industry as a source of funding, research platform and data provider, alongside national research funding opportunities. Given the fundamental role of krill in the Southern Ocean ecosystem, its decline would have cascading effects on predators and essential ecosystem services
Mainstreaming habitat management objectives in an ecosystem-based approach to management of scallop fisheries
No full textScallops are a high-value resource and support major demersal fisheries, particularly in the UK where they are the third most valuable landed species (£60 million in 2024). This study contrasts regional variations in scallop fisheries management in the British Isles compared to the management strategies found in global scallop fisheries that are either Marine Stewardship Council (MSC) certified or uncertified fisheries. Core management measures adopted across all fisheries in this study were the requirement for a fishing license, the recording of catch data, and the enforcement of penalties for regulatory violations. The three main fisheries management measures that differentiated MSC certified fisheries from uncertified fisheries were: adaptive management, the implementation of stock assessments to inform harvest limits and total allowable catch (TAC). Considering the well-understood direct physical impacts of scallop dredging on seabed habitats, it was surprising that while some management measures indirectly protected seabed habitats, few were exclusively designed for this purpose. The review highlights the need for a more explicit ecosystem-based management approach, emphasizing seabed habitat protection and recognizing their role as vital for key life history stages such as spat settlement. This approach would align conservation with industry goals, fostering environmental sustainability and long-term scallop abundanc
Real-time visualization reveals copepod mediated microplastic flux
Full text linkZooplankton are emerging as key actors in shaping the distribution and fate of microplastics in marine environments. Copepods are the predominant taxa in marine zooplankton communities, underpinning food webs and playing vital roles in biogeochemical cycling. Marine copepods have been identified as microplastic reservoirs that likely contribute to the biological transport of microplastics. Evaluating the extent to which copepods contribute to marine plastic cycles requires accurate measures of copepod-mediated microplastic fluxes. To address this critical research gap, real-time visualization is implemented to precisely measure microplastic gut passage time and ingestion intervals. The North Atlantic temperate copepod Calanus helgolandicus was exposed to fluorescent polystyrene beads, polyamide fibers and polyamide fragments under varying food concentrations. Copepods demonstrated consistent microplastic gut passage times (median: 40 min) with food concentration and microplastic shape having no significant effect. This study provides robust estimates of gut passage time and ingestion intervals, establishing a quantitative framework for assessing copepod-mediated microplastic fluxes. Estimated fluxes (∼271 microplastics m⁻³ day⁻¹), based on the mean abundance of C. helgolandicus in the western English Channel (Northeast Atlantic), suggest that copepods may represent key drivers of vertical microplastic transport. These findings advance integration of copepod-driven processes into oceanographic models, reducing uncertainties in microplastic transport predictions and enhancing understanding of microplastics' ecological impacts on marine ecosystems and global biogeochemical cycles
Impact of Extreme Weather Events and Land use on Leptospira Distribution in Vembanad Lake and Associated Disease Outbreaks in Near Shore Areas
No full textLeptospirosis is a water-associated zoonotic disease prevalent in tropical and low-income regions. The pathogen enters the environment through rodent excreta, and extreme weather events—such as floods—enhance its transmission to humans. This study analyses the incidence of leptospirosis in Kerala state, examines the distribution of Leptospira in the water column of Vembanad Lake, a Ramsar site and the largest lake in the state, and investigates the influence of land use patterns and the physical and chemical properties of the water column. Water samples for analysis were collected at approximately 20-day intervals over 12 months from 13 stations in Vembanad Lake. Analysis of the decadal dataset of disease incidence indicates that the region is endemic to leptospirosis, with nearly 50% of the cases reported in 2018—particularly in areas surrounding Vembanad Lake—occurring in September, coinciding with a once-in-a-century flood. A significant positive correlation was observed between rainfall and disease incidence (r = 0.73, p < 0.05). Over the past 50 years, built-up areas around the lake have expanded by nearly 150%, providing less space for water and increasing the likelihood of floods that can transmit pathogens. Molecular surveillance using quantitative real-time PCR revealed that Leptospira is prevalent in the lake, with gene copies ranging from 4.62 × 105 (Log₁₀ 5.67) to 3.98 × 10⁷ (Log₁₀ 7.60) per ml during the rainy season (June–December) and 2.8 × 10⁶ (Log₁₀ 6.63) to 1.53 × 10⁸ (Log₁₀ 8.18) per ml during the dry season (January–May). Results indicate that the distribution of Leptospira in Vembanad Lake is influenced by temperature, pH, and nutrient composition (PO₄ and NO₂) of the water column. This study highlights the prevalence of Leptospira in the lake’s water column and the heightened risk of transmission to humans during extreme weather events. It underscores the need for a multifaceted approach, including molecular and remote sensing-based pathogen surveillance, public awareness initiatives, integrated floodwater management, rodent control measures in urban planning, and targeted interventions to mitigate environmental transmission
Artificial light at night alters seaweed reproductive phenology
Full text linkArtificial light at night (ALAN) is a growing, globally prevalent environmental stressor. It is known to disrupt
biological processes across taxa and biomes, including reproductive phenology in terrestrial plants, but its potential to alter reproductive timings in marine macroalgae remains unexplored. We used reflectance spectrometry to quantitatively assess changes in receptacle ripeness of three fucoid macroalgae species at four field sites
along an ALAN gradient in Plymouth Sound, UK over a six-month period. At sites with elevated ALAN (measured
using Sky Quality Meters, range 16.15–18.76 mag arcsec− 2
, equivalent to 3.75 × 10− 2 –3.38 × 10− 3 cd/m2), expected seasonal patterns of receptacle ripening in Ascophyllum nodosum were reversed, causing receptacles to continue ripening into the winter months as opposed to peaking during the summer. Fucus serratus also continued to ripen in winter when exposed to the highest ALAN levels (16.15 mag arcsec− 2
, 3.75 × 10− 2 cd m− 2). Our results provide some of the first evidence that ALAN disrupts reproductive timings in fucoid macroalgae. Given the critical role of fucoids in coastal ecosystems worldwide, ALAN should be recognised as a potential driver of ecological change in these species. Incorporating ALAN into conservation strategies is essential for protecting these foundational habitats