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Holocene sea-level history from the southern Bohai Sea coast, China: Far-field GIA processes and an associated mid-Holocene sea-level highstand
No full textThe Bohai Sea, located in the innermost part of the East Asian marginal seas, is of particular interest in the studies of relative sea level (RSL) and glacial isostatic adjustment (GIA) due to its apparent far-field position. This study analyzed six cores and one pre-existing archaeological site from the southern Bohai Sea coast, generating 11 sea-level index points (SLIPs) from supratidal, upper tidal, and mid-lower tidal flat sediments using foraminifera tests and sedimentary analysis. All SLIPs were corrected for possible self-compaction, long-term tectonic effect, and the lowering effect due to water extraction. This enabled a high-quality reconstruction of RSL changes over the age range of 9000–3000 cal a BP. The RSL rose rapidly from about −17.19 ± 1.32 m to 1.76 ± 1.32 m MSL between around 9000 and 7000 cal a BP. However, the RSL rise rates quickly decreased from around 8–10 mm/a before 8000 cal a BP to ∼4mm/a by 7000 cal a BP. After 7000 cal a BP, the RSL continued to rise, reaching its peak of 2.44 ± 1.34 m MSL around 6000 cal a BP followed by a gradual decline to the present height at 3000–4000 cal a BP, with a maximum falling rate of 1.2 mm/a around 5000 cal a BP. Comparisons of the reconstructed RSL in this study with those from other non-deltaic regions, including the inner Hangzhou Bay and the surrounding coasts of western Bohai Sea, as well as with GIA predictions by ICE6G, ANU, and region-specific ‘final model’ reveal: (1) a significant and long-term early-to-mid Holocene continental levering effect on the southern Bohai Sea coast; (2) a close fit with the region-specific ‘final model’, albeit with SLIPs that fall slightly below predictions from 9000 to 8000 cal a BP and form a distinct mid-Holocene highstand above model projections after 7000 cal a BP; (3) these data-model misfits may result, in the former case, from the GIA model\u27s Holocene ice melting history not embedding accelerated sea-level rise events, and in the latter, from the presence of a relatively strong upper mantle at the southern Bohai Sea coast, rather than the extremely weak upper mantle assumed for the Bohai Sea region.</span
Presence and potential impact of anthropogenic nesting materials on a colonial breeding waterbird
No full textDespite the vital importance of wetlands globally, these habitats have increasingly received anthropogenic materials, such as plastics, which can impact the wildlife these habitats support. Despite commonly found in the nests of Eurasian spoonbill (Platalea leucorodia), the presence of such materials has never been quantified. Here, we monitored the occurrence of anthropogenic nesting materials (ANM) in spoonbill nests in the Camargue wetland in Southern France during two breeding seasons (2021−2022). We also investigated their potential function by associating their presence with breeder experience (based on their age) and hatching success. Out of 439 nests, 39 % contained at least one anthropogenic material item, usually plastic of sheet-like shape and white-transparent colours. Throughout the breeding season, the proportion of ANM in the nest lining increased, coinciding with a decrease in natural materials (i.e. vegetation). A higher proportion of natural green materials was detected during the egg phase compared to other phases of nest development. Our results did not support a correlation between the proportion of ANM and breeder experience, nor with hatching success. Further studies (e.g., physiological through necropsy or fine temperature nest assessment) may disentangle the benefits and adverse effects of such materials on waterbird breeding success.</span
Global interfertility and heterosis in sugar kelp populations: a next step in sugar kelp breeding
No full textThe potential of seaweed aquaculture is restricted by high labor, production and processing costs, leading to low economic viability. Selective breeding can improve yields and cultivation efficiency, thereby decreasing production costs. Until now, genetic resources as input for Saccharina latissima breeding trials have been sourced strictly locally, due to concerns regarding outplanting genetically exogenous material in local waters. Here we study, for the first time, worldwide interregional fertility of the seaweed S. latissima, in order to assess the potential of including global S. latissima genetic resources for selective breeding with regard to heterosis. We quantified the yield (as an indicative aquacultural performance) and morphological traits of intra- and interregional S. latissima hybrids originating from a broad range of locations in a common garden experiment. Our results show that the practical application of worldwide S. latissima genetic resources in breeding programs is feasible based on global interfertility. We found a wide morphological diversity of hybrids and observed significant heterosis in interregional hybrids. The degree of heterosis could not be linked to geographic distance. These findings reveal that worldwide genetic resources can considerably contribute to S. latissima breeding programs and could offer a major next step in improving yields and quality traits.</span
Acoustic positioning for deep sea neutrino telescopes with a system of piezo sensors integrated into glass spheres
No full textPosition calibration in the deep sea is typically done by means of acoustic multilateration using three or more acoustic emitters installed at known positions. Rather than using hydrophones as receivers that are exposed to the ambient pressure, the sound signals can be coupled to piezo ceramics glued to the inside of existing containers for electronics or measuring instruments of a deep sea infrastructure. The ANTARES neutrino telescope operated from 2006 until 2022 in the Mediterranean Sea at a depth exceeding 2000 m. It comprised nearly 900 glass spheres with 432 mm diameter and 15 mm thickness, equipped with photomultiplier tubes to detect Cherenkov light from tracks of charged elementary particles. In an experimental setup within ANTARES, piezo sensors have been glued to the inside of such – otherwise empty – glass spheres. These sensors recorded signals from acoustic emitters with frequencies from 46545 to 60235 Hz. Two waves propagating through the glass sphere are found as a result of the excitation by the waves in the water. These can be qualitatively associated with symmetric and asymmetric Lamb-like waves of zeroth order: a fast (early) one with ve ≈ 5 mm/μs and a slow (late) one with v? ≈ 2 mm/μs. Taking these findings into account improves the accuracy of the position calibration. The results can be transferred to the KM3NeT neutrino telescope, currently under construction at multiple sites in the Mediterranean Sea, for which the concept of piezo sensors glued to the inside of glass spheres has been adapted for monitoring the positions of the photomultiplier tubes.</span
Effects of chemical leachates from offshore wind farm infrastructure on heart rate and valve gape of blue mussels
No full textOffshore wind farms (OWFs) play a key role in combating climate change, but the coatings used to protect submerged infrastructure can leach potentially harmful chemicals into the marine environment. These leachates may affect marine species colonizing OWF structures or being cultured near OWFs, such as blue mussels. To assess the impacts, we monitored valve gape behaviour and heart rate in Mytilus edulis exposed to coating leachates under controlled conditions, followed by a thermal ramping to assess potential constraints in their stress performance. Using non-targeted screening with two-dimensional gas chromatography and high-resolution mass spectrometry, we identified nine chemicals in the leachates plausibly assigned to the coatings, including alcohols, ketones, lactones, bromobenzenes, dibromophenols, and polycyclic aromatic hydrocarbons. At constant temperatures, exposed mussels showed both up to 12 % reduced and up to 18 % increased daily cardiac arrest compared to control mussels. However, during cardiac activity heart rate and valve gape were similar among treatments. Leachate exposure did not lead to reductions in fitness endpoints during the thermal ramping, i.e. the temperature at which heart rate was maximal (21.3 ± 0.4 °C) and valves started to close (19.2 ± 0.6 °C). Non-targeted screening does not allow for comparisons of chemical concentrations from field samples, yet the painted surface to volume of seawater ratio used here potentially led to much higher leachate concentrations than any environmentally relevant conditions. Future research on leachates from other OWF sources, such as sacrificial anodes, is needed to gain a comprehensive understanding of ecological risks and support sustainable OWF development
Phylogenomic analyses reveal that <i>Panguiarchaeum</i> is a clade of genome-reduced Asgard Archaea within the Njordarchaeia
No full textThe Asgard archaea are a diverse archaeal phylum important for our understanding of cellular evolution because they include the lineage that gave rise to eukaryotes. Recent phylogenomic work has focused on characterizing the diversity of Asgard archaea in an effort to identify the closest extant relatives of eukaryotes. However, resolving archaeal phylogeny is challenging, and the positions of 2 recently described lineages—Njordarchaeales and Panguiarchaeales—are uncertain, in ways that directly bear on hypotheses of early evolution. In initial phylogenetic analyses, these lineages branched either with Asgards or with the distantly related Korarchaeota, and it has been suggested that their genomes may be affected by metagenomic contamination. Resolving this debate is important because these clades include genome-reduced lineages that may help inform our understanding of the evolution of symbiosis within Asgard archaea. Here, we performed phylogenetic analyses revealing that the Njordarchaeales and Panguiarchaeales constitute the new class Njordarchaeia within Asgard archaea. We found no evidence of metagenomic contamination affecting phylogenetic analyses. Njordarchaeia exhibit hallmarks of adaptations to (hyper-)thermophilic lifestyles, including biased sequence compositions that can induce phylogenetic artifacts unless adequately modeled. Panguiarchaeum is metabolically distinct from its relatives, with reduced metabolic potential and various auxotrophies. Phylogenetic reconciliation recovers a complex common ancestor of Asgard archaea that encoded the Wood–Ljungdahl pathway. The subsequent loss of this pathway during the reductive evolution of Panguiarchaeum may have been associated with the switch to a symbiotic lifestyle, potentially based on H2-syntrophy. Thus, Panguiarchaeum may contain the first obligate symbionts within Asgard archaea besides the lineage leading to eukaryotes
gSeaGen code by KM3NeT: An efficient tool to propagate muons simulated with CORSIKA
No full textThe KM3NeT Collaboration has tackled a common challenge faced by the astroparticle physics community, namely adapting the experiment-specific simulation software to work with the CORSIKA air shower simulation output. The proposed solution is an extension of the open source code gSeaGen, which allows the transport of muons generated by CORSIKA to a detector of any size at an arbitrary depth. The gSeaGen code was not only extended in terms of functionality but also underwent a thorough redesign of the muon propagation routine, resulting in a more accurate and efficient simulation. This paper presents the capabilities of the new gSeaGen code as well as prospects for further developments.</span
Diatom colonisation and biofilm metal bioaccumulation: Can Indigenous Knowledge Systems aid the ecological engineering of urban coastlines?
No full textMarine engineered structures alter the coastal ecosystems\u27 functionality, replacing natural substrates with flat surfaces, often negatively impacting biodiversity. While providing coastal protection, artificial structures can hinder the initial colonisation by biofilm and the recruitment of coastal species. Greening the grey infrastructure through nature-based interventions is increasingly used to enhance biodiversity in artificial structures. This study explores the potential of the sedge Cyperus textilis and its Indigenous Knowledge applications as a substrate for coastal eco-engineering at an urbanised site on the southeast coast of South Africa. Diatom succession and metal bioaccumulation on the deployed trial-version designs (imizi structures) were monitored for a month, with samples collected at six, twelve, twenty-four, seventy-two hours, one and two weeks, and one month after deployment. Water quality, including dissolved nutrients and metal concentrations, were assessed near the substrates. Findings indicated that diatom colonisation occurred within twelve hours, with initial species including Fragilaria pulchella, Neofragilaria nicobarica, Navicula sp. and Grammatophora undulata, followed by a significant increase (4.6 times) in species diversity from 5 to 23 diatoms after one week. Metal bioaccumulation of aluminium, iron, zinc, manganese and arsenic was higher in the biofilm developing on the substrate compared to its surrounding environment (imizi substrate and water), suggesting the potential bioremediating capabilities of the biofilm on the nature-based material. These findings indicate the potential suitability of using Indigenous Knowledge-based materials for coastal eco-engineering practices as promoters of primary productivity, with the added potential of the plant C. textilis for bioremediation of toxic metals such as arsenic.</span
Microbiome dynamics in early life stages of the precious Mediterranean Red Coral <i>Corallium rubrum</i>
No full textMicrobial colonisation in the early life stages of corals plays a critical role in their fitness, but the mechanisms by which microbial symbionts are acquired—whether from parental colonies, the environment, or both—remain poorly understood, particularly in octocorals. Although they are the second most abundant coral group on tropical reefs and contribute significantly to the structural complexity of Mediterranean coral reefs, their microbial dynamics are largely unexplored. In this study, we investigated the acquisition of the bacterial microbiota in the red coral Corallium rubrum, a precious coral. By analysing the composition of the bacterial community at different early life stages, including newly released larvae, 5- and 10-day-old larvae, 3-month-old settlers, 1-year-old recruits and 3-year-old juveniles, we are gaining new insights into the development of its microbiome. Using a direct PCR-based 16S rRNA metabarcoding approach, we performed high-resolution microbiome analyses at the level of individual larvae and settlers. Our results show that the bacterial microbiota of C. rubrum matures after the first year of life. Notably, dominant symbionts, such as Spirochaetaceae and BD72BR169 Gammaproteobacteria, were absent in larvae, settlers and recruits, suggesting that they were likely acquired horizontally from the environment. These findings improve our understanding of the microbial colonisation and development of C. rubrum and shed light on the potential role of its bacterial community in holobiont function.</span
Unseen experts of the sea: Fishers\u27 local ecological knowledge reveals Elasmobranch hotspot decline around Curaçao, Dutch Caribbean
No full textFishing pressure is the primary threat to coastal elasmobranch populations, and understanding its impact requires long-term regional data—often lacking in complex, small-scale fishery settings. This is the case for Curaçao, a southern Dutch Caribbean island with an unmonitored artisanal fishery where, according to anecdotes, elasmobranchs have severely declined but continue to be landed. In such data-limited regions, fishers\u27 local ecological knowledge (FLEK) is a valuable tool for reconstructing historical baselines. Using FLEK from 21 surveys, we quantified historical and current elasmobranch diversity around Curaçao. Participatory mapping identified spatial distributional changes of 14 elasmobranch species, comparing the time of the surveys with fishers\u27 career beginnings. Temporal trends were analysed alongside shifts in fishing efforts, socioeconomic contexts and perceptions of fishery management. Between 1957 and 2009, we identified 36 spatial hotspots of elasmobranch richness, which declined to 14 hotspots from 2010 to 2022, with a 4.3-fold greater likelihood of hotspots occurring in the past. Species richness in these areas significantly decreased from 7.44 ± 1.00 (mean ± s.e.) to 3.00 ± 1.18 species, while the number of fishers increased from 2.86 ± 0.23 fishers to 5.14 ± 0.49 per hotspot. Although not targeted, incidental elasmobranch catches are commonly retained. Most fishers expressed a desire for increased inclusion in fishery management but viewed elasmobranch-specific measures as unnecessary, perceiving local populations as healthy. We thus provide critical spatial baseline data for evidence-based conservation of elasmobranchs around Curaçao while emphasising the benefits and importance of engaging small-scale fishers in managing elasmobranch populations.</span