Search Results (81)

The Caribbean Coastal Marine Productivity (CARICOMP) program was conceptualized in 1985 to monitor coral reefs, seagrass beds, and mangrove forests at multiple sites across the wider Caribbean. Mangrove monitoring was focused on the dominant Caribbean species, red mangrove (Rhizophora mangle). Forest structure and productivity were monitored at 21 sites (18 countries) across different geomorphological settings, from tropical to subtropical mainland and island systems. Here, we provide the key findings from the CARICOMP mangrove data collected, mostly from 1992 to 2013, to assess spatial and temporal variability across the region. Red mangrove above-ground biomass averaged 190 t ha⁻¹ (far higher than previously reported) but ranged widely across sites from 33 to 590 t ha⁻¹, equating to an average above-ground ‘blue carbon’ of 84 t ha⁻¹ (range 15–260 t ha⁻¹). Tree density averaged 3237 trees ha⁻¹, tree basal area averaged 19.7 m² ha⁻¹, tree height averaged 6.1 ± 2.8 m, and seedling density varied from 1.2 to 74 seedlings m⁻² across the sites. Among the environmental factors that influence mangroves, local temperature and rainfall explained 48% of the variability in measured tree structure parameters. Annual litterfall, as a proxy for productivity, measured on average 1.24 ± 0.70 kg m⁻² yr⁻¹, with 60% of the total litterfall composed of leaves. Litterfall varied seasonally by 42%. No relationship was apparent between litterfall and seasonal ocean–atmosphere climate indices (ONI and AMM). With exception of the three most southwesterly CARICOMP sites, hurricanes and tropical storms impacted the mangrove sites repeatedly, resulting in considerable damage. A direct strike by a category-4 hurricane in 1998 in Dominican Republic killed 67% of the red mangrove trees, lowered above-ground biomass by 91%, basal area by 89%, litterfall by 63%, and resulted in the subsequent growth of many tall and thin saplings, totally changing the structure of the forest ecosystem in the first few years after the hurricane. In comparing mangrove systems, major differences may be explained by time elapsed since the last destructive event (hurricane) affecting each site. This highlights the fact that despite an increasing focus on preserving these valuable ecosystems, they are still highly vulnerable to natural hazards and likely to face a poor outcome under ongoing climate change. Full article

Seagrass beds are among the most productive and ecologically valuable coastal ecosystems. However, temperate nearshore seagrass beds exposed to urban stressors remain understudied. From 2020 to 2024, this study investigated seagrass communities, environmental factors, and benthic macrofauna in Qingdao’s coastal bays (Qingdao Bay, Huiquan Bay and Tangdao Bay) using field sampling and remote sensing. Redundancy analysis (RDA), Spearman correlation, and PERMANOVA were applied to clarify the ecological response relationships among these components. Results revealed significant spatiotemporal variations: Qingdao Bay experienced severe degradation with an 88% decline in belowground biomass. Huiquan Bay showed shoot height increases but ecological instability, while Tangdao Bay maintained relatively stable conditions. Mollusks dominated Qingdao Bay (67.4%), whereas annelids were prevalent in Huiquan Bay (51.8%) and Tangdao Bay (69.6%). Tangdao Bay supported the most complex and stable benthic communities. Water depth acted as a stressor to seagrass growth, while the role of dissolved oxygen and salinity was complex, exhibiting context-dependent relationships with seagrass parameters. Dissolved inorganic nitrogen and reactive phosphate were shared positive drivers for both seagrasses and macrofauna. This study conclusively links specific environmental drivers to seagrass ecosystem dynamics, delivering essential insights for effective ecological management and restoration strategies. Full article

Bottlenose dolphins (Tursiops sp.) are opportunistic foragers with global distributions that utilize diverse feeding tactics based on environmental factors, habitat features, prey behavior, group dynamics, and genetics. We describe a unique foraging tactic regularly observed in the confluence of dredged shipping channels with high anthropogenic disturbance, and explore potential abiotic (temporal, tidal, habitat) drivers of the behavior. A shore-based digital theodolite was used from 2021 to 2022 to observe common bottlenose dolphins (T. truncatus) foraging within a current in a technique we term Orient-Against-Current (OAC). During OAC, dolphins position themselves facing into the flow of a current, swimming at a speed to maintain a stationary position within the current, and feed while prey move with the current towards them. Orient-Against-Current occurred in all seasons and throughout daylight hours, particularly during the winter and spring. Dolphins engaged in OAC during ebb tides and intermediate current speeds (1–2 knots), but not during slack tides. As OAC occurred closer to shoreline structures (i.e., seawalls, concrete blocks) than to mangroves and natural seagrass beds, it appears that hard human-engineered structures aid in prey capture during OAC. Knowledge of dolphin foraging techniques can aid in understanding behavioral plasticity shaped by anthropogenically altered environments in industrialized coastal areas. Full article

Vegetated intertidal ecosystems, such as seagrass meadows, salt marshes, and macroalgal beds, are vital for biodiversity, coastal protection, and climate regulation; however, they remain highly vulnerable to anthropogenic and climate-induced stressors. This study aims to assess interannual changes in intertidal vegetation cover along the Portuguese mainland coast from 2015 to 2024 using Sentinel-2 satellite imagery calibrated with high-resolution multispectral unoccupied aerial vehicle (UAV) data, to determine the most accurate index for mapping intertidal vegetation. Among the 16 indices tested, the Atmospherically Resilient Vegetation Index (ARVI) showed the highest predictive performance. Based on a model relating intertidal vegetation cover to this index, an ARVI value greater than or equal to 0.214 was established to estimate the area covered with intertidal vegetation. Applying this threshold to time-series data revealed considerable spatial and temporal variability in vegetation cover, with estuarine systems such as the Ria de Aveiro and the Ria Formosa showing the greatest extents and marked fluctuations. At the national level, no consistent overall trend was identified for the study period. Despite limitations related to satellite image resolution and single-site validation, the results demonstrate the feasibility and utility of combining UAV data and satellite indices for long-term, large-scale monitoring of intertidal vegetation. Full article

Labyrinthulomycetes protists play important roles in organic matter decomposition and nutrient cycling in marine ecosystems. To better understand their distribution and potential ecological functions in Caofeidian seagrass beds of the Bohai Sea, we conducted high-throughput sequencing of samples collected from multiple habitats, including leaves (L), rhizosphere (R), sediments (S), and seawater (W). Our results revealed distinct habitat-specific patterns of community composition. Oblongichytrium and Stellarchytrium were dominant in certain samples, exhibiting clear differences across stations. Oblongichytrium showed particularly high abundance in leaf and seawater samples, likely reflecting the availability of particulate and dissolved substrates enriched by seagrass beds. In the rhizosphere, Sicyoidochytrium, Stellarchytrium and Labyrinthula were enriched, whereas unclassified Labyrinthulomycetes and Thraustochytriaceae lineages prevailed in seawater and specific leaf samples. Notably, a substantial proportion of sequences corresponded to unclassified lineages, potentially representing uncultured “seagrass-associated” taxa. Compared with previous reports, our study revealed both a significantly higher abundance of Stellarchytrium and a remarkably greater proportion of unclassified lineages, suggesting unique features of Labyrinthulomycetes communities in the Caofeidian seagrass ecosystem. These findings provide new insights into the ecological roles of Labyrinthulomycetes in seagrass beds and offer an important reference for future taxonomic and functional studies of this group. Full article

This study provides the first comprehensive characterization of benthic macrofaunal communities in the Loukkos estuary, highlighting their spatial and seasonal variability and the environmental factors shaping their structure. A total of 47 species were identified across 12 site–season combinations, dominated by molluscs (47%), polychaetes (23%), and crustaceans (21%). Species richness varied considerably along the estuarine gradient, ranging from fewer than five species in the upstream sector to up to 30 species downstream. Overall, higher diversity was observed in the downstream areas and during the dry season. Macrofaunal density also exhibited substantial variability, ranging from 95 ind.m⁻² to 14,852 ind.m⁻², with a mean density of 2535 ± 4058 ind.m⁻². Multivariate analyses identified four distinct benthic assemblages structured primarily by spatial factors (ANOSIM R = 0.86, p = 0.002), with negligible seasonal effect (R = −0.03, p = 0.6). Assemblages ranged from marine-influenced communities at the estuary mouth dominated by Cerastoderma edule, through rich and diverse seagrass-associated communities in the lower estuary dominated by Bittium reticulatum, and moderately enriched mid-estuary communities characterized by Scrobicularia plana and Hediste diversicolor, to species-poor upstream communities dominated by the tolerant species H. diversicolor. Canonical analysis showed that salinity and vegetation explain nearly 40% of the variation in benthic assemblages, highlighting the key role of Zostera seagrass beds as structuring habitats. Moreover, upstream anthropogenic pressures alter environmental conditions, reducing benthic diversity and favoring tolerant species. Full article

Seagrass beds provide essential ecosystem services, such as habitat for marine life, water quality purification, carbon sequestration, and climate regulation. For the Changshan Archipelago, which relies heavily on marine resources, the growth and development of seagrass beds are key factors affecting aquaculture. This study is based on data collected from a survey conducted in the nearshore waters of the Changshan Archipelago in August 2022, encompassing seagrass distribution and water sample data. The water samples were analyzed for various parameters, including salinity, suspended solids, pH, dissolved oxygen, sea temperature, nitrite-nitrogen, nitrate-nitrogen, and ammonia-nitrogen concentrations. A habitat suitability assessment of the seagrass beds in the Changshan Archipelago was conducted. The study calculated the suitability index for each environmental variable based on the abundance index, and then established a Habitat Suitability Index model using a weighted allocation method. The results indicate that the seagrass bed area in the study region is primarily composed of excellent and suitable habitats. The concentration of inorganic nutrients is a key factor influencing seagrass growth. The HSI model not only identifies the hierarchical distribution of habitats in seagrass areas, but also detects potential suitable habitats for seagrass. This provides scientific reference for future seagrass bed resource protection and artificial cultivation efforts. Full article

Seagrass is a key primary producer in coastal ecosystems; however, most studies on seagrass-benthos interactions have focused on subtidal zones. Some species such as Zostera japonica grow in intertidal flats; however, their ecological functions remain unclear. Understanding whether intertidal seagrass beds contribute to benthic abundance and diversity can provide insights that facilitate tidal flat conservation. The present study clarifies the role of intertidal Z. japonica as a food source for benthos. Field surveys were conducted in an intertidal flat in Matsushima Bay, Japan. Five benthic species (Batillaria cumingii, Umbonium costatum, Phacosoma japonicum, Nereididae, and Paguroidea) were identified. Carbon and nitrogen stable isotope ratios (δ¹³C, δ¹⁵N) and fatty acid compositions of sediment organic matter, seawater, and target benthos were analyzed to determine food sources. The results showed that B. cumingii actively consumed Z. japonica-derived organic matter present in both seagrass and sandy sediments. Z. japonica also influenced bacterial community structure, providing a favorable habitat for Nereididae. Filter feeders (U. costatum and P. japonicum) exhibited minimal reliance on Z. japonica-derived organic matter. The findings suggest that, similar to subtidal seagrass ecosystems, intertidal seagrass meadows support benthic communities by supplying organic matter and enhancing bacterial production. Full article

The tropical coral Siderasterea radians is typically found in mangrove areas, seagrass beds, and environments tolerated by few other scleractinians in the Caribbean and South Florida. Siderastrea radians experience bleaching stress in Buttonwood Sound in Florida Bay during April–May, a time when the seawater is below bleaching temperatures. Stress first appears as a pink coloration due to the presence of fluorescent pigments protecting the coral tissue and algal symbionts from exposure to excessive sunlight/UV light. Surveys of S. radians in areas frequented by parrotfish showed that up to 38.5% of the corals were pink, with about a quarter of all the corals having bite marks. In areas not frequented by parrotfish, only 3.2% of the corals were pink, and none had bite marks. A seasonal analysis in parrotfish-frequented seawater showed S. radians contained among the lowest tissue biomass and density of symbiotic algae during April–May 2010–2017, often looking pink. It is hypothesized that seawater temperature is not the cause of bleaching in Buttonwood Sound during April–May but rather predation by the rainbow parrotfish Scarus guacamaia. Full article

Background: The Merulinidae family belonging to the order Scleractinia is mainly distributed in the Indo-Pacific and Caribbean regions and often constitute the most dominant species of coral reefs. Mitochondrial genome is a key tool for studying the phylogeny and adaptation. Only a few studies have conducted the characteristics analyses of mitochondrial genome in the Merulinidae family. Methods: Therefore, we used high-throughput sequencing technology to describe the mitochondrial genome of Platygyra daedalea, a member of this family. Bioinformatics was used to analyze the composition characteristics of the mitochondrial genome of 10 Merulinidae species. Results: The mitochondrial genome of P. daedalea had a total length of 16,462 bp and a GC content of 33.0%. Thirteen unique protein-coding genes (PCGs), two transfer RNA (tRNA) genes, and two ribosomal RNA (rRNA) genes were annotated. Each species of Merulinidae had 13 unique PCGs in the mitochondrial genome. In contrast, the number of tRNAs and rRNAs significantly varied in Merulinidae species. Collinearity and gene rearrangement analyses indicated that the mitochondrial evolution of species in the Merulinidae family was relatively conserved. Divergence time analysis indicated that Merulinidae originated in the Oligocene, whereas the Platygyra genus originated in the Miocene. The formation and intraspecific divergence of coral species were consistent with geological changes in the ocean. Conclusions: The results of this study help better understand the characteristics of the mitochondrial genome in the Merulinidae family and provide insights into the utility of mitochondrial genes as molecular markers of phylogeny. Full article

Reducing carbon emissions and increasing carbon sinks have become the core issues of the international community. Although coastal blue carbon ecosystems (such as mangroves, seagrass beds, coastal salt marshes and large algae) account for less than 0.5% of the seafloor area, they contain more than 50% of marine carbon reserves, occupying an important position in the global carbon cycle. However, with the rapid development of the economy and the continuous expansion of human activities, coastal wetlands have suffered serious damage, and their carbon sequestration capacity has been greatly limited. Ecological restoration has emerged as a key measure to reverse this trend. Through a series of measures, including restoring the hydrological conditions of damaged wetlands, cultivating suitable plant species, effectively managing invasive species and rebuilding habitats, ecological restoration is committed to restoring the ecological functions of wetlands and increasing their ecological service value. Therefore, this paper first reviews the research status and influencing factors of coastal wetland carbon sinks, discusses the objectives, types and measures of various coastal wetland ecological restoration projects, analyzes the impact of these ecological restoration projects on wetland carbon sink function, and proposes suggestions for incorporating carbon sink enhancement into wetland ecological restoration. Full article

Low-salinity conditions are generally used in land-based cultivation to promote the germination and growth of Zostera marina L. and to improve the restoration effect of seagrass beds. Different salinity conditions lead to morphological and physiological differences. To investigate the impacts of salinity and osmotic pressure on the germination and early development of Zostera marina seeds, this study utilized seawater with different salinity conditions and PEG-6000 solutions to simulate various non-ionic osmotic pressures and examine the germination, cotyledon growth, and leaf differentiation over 28 days, as well as determine the biochemical traits on days 1, 3, 5, and 7. The results show that the cumulative germination rate in LS-0 was 91.6%, but it was not significantly affected by the PEG solutions. The different salinities (5, 10, and 15) had no significant effect on the germination rate, which ranged from 76.4% to 78.8%: low salinity and low osmotic pressure stimulated the germination by accelerating the water uptake through increased osmotic pressure differences. The leaf differentiation was regulated by the osmotic pressure and salinity. In LS-10, the most used condition, the leaf differentiation rate was 35.2%, while PEG-10 displayed 6.4%. The total soluble sugar and soluble protein in the seeds decreased. Antioxidant enzyme activities were activated under low-salinity conditions, which supported germination within a tolerable oxidative stress range. Full article

“Blue carbon” refers to the carbon sequestered by the world’s oceanic and coastal ecosystems, particularly through coastal vegetation such as mangroves, salt marshes, seagrasses, and marine macroalgae. These ecosystems play a crucial role in the global carbon cycle by serving as significant carbon sinks, absorbing carbon dioxide from the atmosphere and storing it in biomass and sediments over long periods. This study explores the use of environmental DNA (eDNA) to detect marine macrophytes and microalgae assemblages contributing to blue carbon in sediments across various coastal ecosystems. The research addresses the challenges of traditional monitoring methods by utilizing high-throughput sequencing of the 18S-V9 region amplified using eDNA from sediment samples collected at eight locations in the United States and South Korea. The results reveal a diverse array of taxa, underscoring the variability in community composition across different conditions. Notably, sites with seagrass beds and Ulva blooms showed distinct patterns in microalgal community structure. This study underscores the potential of eDNA analysis in providing comprehensive insights into the biodiversity of marine macrophyte ecosystems, thus informing conservation efforts and enhancing the understanding of marine ecological dynamics. Full article

Endemic Mediterranean seagrass Posidonia oceanica is highly endangered today as it lives in a narrow infralittoral zone intensely exposed to human impact. P. oceanica beds are especially endangered in the Adriatic Sea as the central and northern Adriatic could be considered as a naturally suboptimal area for P. oceanica growth. In this research, we used some standard descriptors of Posidonia meadows at different locations and depths and determined the biochemical parameters (phenolic compounds, photosynthetic pigments, and enzyme activities) in its leaves in order to find possible correlations among the measured parameters and environmental conditions. Photosynthetic pigments were shown to be sensitive biomarkers in the assessment of P. oceanica response to different light conditions, but more research is needed to elucidate the impact of other environmental factors. Overall, the results of this research show that the studied parameters are good bioindicators of a meadow’s environmental state, but it is necessary to analyze a number of diverse indicators together to properly characterize the state of a particular P. oceanica meadow. This approach would be very useful in the determination of P. oceanica conservation status, which is the first step towards improving monitoring protocols and implementing appropriate conservation measures. Full article

Commonly found in tropic and subtropic seagrass beds, lucinid clams host sulfur-oxidizing bacteria within their gills. These symbionts are crucial in converting phytotoxic sulfide in the sediment into less harmful sulfate, thus enhancing the environment for seagrasses and associated biota. We recently uncovered small clams within a Zostera marina seagrass bed situated in a lagoon on Jeju Island, off the south coast of Korea. These bivalves, with shell lengths of up to 7 mm, exhibited distinct features, including thick and hypertrophied gills, inflated and ovoid shells with a shell height/shell length ratio of 0.99, and the absence of a sulcus on the external shell surface. These characteristics align closely with those of Pillucina pisidium, a lucinid clam species originally reported in Japan. Analysis of the cytochrome b gene partial sequences of the clams from Jeju Island revealed a 100% match with P. pisidium reported in Japan, confirming their identity. Moreover, we successfully assembled the complete mitochondrial genome of P. pisidium for the first time, revealing a circular genome spanning 21,059 bp. Additionally, we constructed a phylogenetic tree using 13 protein-coding genes (PCGs) extracted from the mitochondrial genome of P. pisidium. Notably, P. pisidium formed a distinct clade within the subclass Autobranchia alongside other lucinid clams in the phylogenetic tree. However, within the family Lucinidae, synteny analysis of the 13 PCGs revealed diverse gene arrangement patterns, indicating considerable divergence. This divergence underscores the need for an extensive examination of Lucinidae mitochondrial genomes to elucidate the phylogenetic ties more precisely within the family, highlighting P. pisidium’s distinct evolutionary path within the family Lucinidae. Full article