Microplastics are among the most common forms of pollution found in marine environments, and their small size allows them to be easily ingested by marine biota. Exaiptasia pallida is a solitary anemone native to the western Atlantic that harbors symbiotic dinoflagellates, like those of reef-building corals, and passively feeds on prey, like brine shrimp. To assess the influence of microplastics on E . pallida , laboratory experiments were conducted in which symbiotic and aposymbiotic anemones were exposed to 100 Âμm red polystyrene microplastic beads with and without brine shrimp. The ingestion of microplastics by the anemones was measured after 3 hr, and egestion of microplastics was measured after 24 and 48 hr following initial exposure. Oxidative stress and photosynthetic impairment have been reported in sea anemones following contaminant exposure; therefore, the quantum yield of photosystem II (YPSII) and maximum electron transport rate (ETRmax) were assessed in symbiotic anemones at 0, 24, and 48 hr. Antioxidant enzymes (glutathione peroxidase and catalase) were assessed in both symbiotic and aposymbiotic anemones 48 hr following the initial exposure. Exaiptasia pallida consumed polystyrene in every treatment, and both the presence of brine shrimp and symbiotic state significantly increased the microplastic ingestion. Unfed, symbiotic anemones ingested 5% of the microplastics offered, whereas symbiotic anemones fed brine shrimp consumed 16% of the microplastics offered. Likewise, aposymbiotic anemones consumed 16%–18% of the microplastics offered to them, independent of the presence of brine shrimp. No changes in YPSII or ETRmax were observed in symbiotic anemones exposed to microplastics. Aposymbiotic anemones had a greater ingestion rate of polystyrene microbeads than symbiotic anemones, and catalase activity was increased in aposymbiotic anemones exposed to microplastics. These results suggest that bleached (aposymbiotic) E . pallida may be more vulnerable to polystyrene exposure in the environment. This is the first study to demonstrate the effects of polystyrene in E . pallida . These findings can be used in future studies to assess the environmental impacts of polystyrene on cnidarians.
Artificial reefs (ARs) are increasingly deployed to mitigate the degradation of natural marine ecosystems; however, quantitatively resolving early-stage, multispecies colonization at millimeter–centimeter scales remains challenging under field conditions. This study evaluates an uncertainty-aware workflow integrating Structure-from-Motion (SfM) underwater photogrammetry and Multiscale Model-to-Model Cloud Comparison (M3C2) for multitemporal structural-change detection on two purpose-built AR modules (1.0 × 1.0 m) deployed at about 10 m depth off Silifke, Mersin. Six underwater surveys were conducted over one year (Nov 2023–Dec 2024), complemented by laboratory geodetic control for independent validation. Dense point clouds were reconstructed from overlapping imagery and assessed using total-station check points (CPs), yielding millimetric positional accuracy [Three-Dimensional Root Mean Square Error (3D RMSE): 1.56–2.10 mm; Epoch 2 excluded due to sand burial of CPs]. Geometric consistency between the laboratory baseline and the postdeployment underwater baseline was further supported by Cloud-to-Cloud (C2C) comparison (means: 0.7–1.0 mm). M3C2 analyses against the underwater baseline (Epoch 1) produced Level of Detection at 95% confidence (LoD 95% ) thresholds of 2.06–3.14 mm (AR1) and 2.08–2.91 mm (AR2) and revealed statistically significant positive surface displacements consistent with progressive colonization, with cumulative surface growth of about 37 mm (AR1) and about 44 mm (AR2) over the monitoring period. The results demonstrate that SfM-based underwater photogrammetry coupled with M3C2 provides a noninvasive, repeatable structural-change metric that complements (rather than replaces) conventional in-water ecological surveys for AR monitoring.
Sharks are known worldwide for their negative interactions with humans, although these are rare. Public fear of these animals increased after the release of the film Jaws (1975), despite only a small fraction of the 547 currently valid species being involved in incidents. In Brazil, the first records of shark-inflicted injuries date back to the 19th century, but from the 1990s onwards they became increasingly frequent, mainly in Pernambuco, where 82 of the 124 documented cases occurred. In this work, we analyzed all official records of shark bites on the Brazilian coast, evaluating the information contained in different databases (International Shark Attack File, Global Shark Attack File, and Committee for the Monitoring of Shark Incidents) and testing the relationships among quantitative and discrete variables, such as shark species involved, season, daytime period, lunar phase, victim's gender, severity of injuries, human activity during the incident, and water temperature. A greater frequency of incidents was observed under the full and new lunar phases, and in the early afternoon. Most bites were attributed to the tiger shark (Galeocerdo cuvier), mainly in winter. The large size of the animals combined with high bather density and limited access to prompt and effective first aid may explain the high rate of encounters. Nevertheless, these are mostly isolated events and do not represent a national-scale threat, except in the case of the Recife Metropolitan Region.
Sexual reproduction is essential for enhancing the genetic diversity of seagrasses, allowing these clonal organisms to be more adaptive and resistant to disturbances. However, the flowering and fruiting characteristics of tropical seagrass species remain largely unknown, with limited phenological information widely available and described. The male flowers of Syringodium isoetifolium were identified 26 d after cyme inflorescence was observed, while the first female flowers were identified 11 d after the males were identified. A total of 14 male and 6 female flowers from five male and three female flowering shoots were identified during the flowering period from April to July 2025, resulting in a 3:5 female to male flower sex ratio. All six female flowers were artificially pollinated using the available pollen, and two fruits were observed after 3 d. The fruiting plants exhibited a reduction and loss of belowground biomass 34 d after fruiting was observed. The documentation of tropical seagrass flowering and fruiting can provide vital information for field monitoring and seagrass phenology research. The successful pollination observed in this ex situ study suggests the potential value of intervention in enhancing fruiting success. However, due to the observational nature of this study in ex situ and semicontrolled conditions, these preliminary observations are not conclusive but may have implications for S . isoetifolium reproductive ecology.
Spawning of Porites cf. lutea hard corals was observed on 17 May, 2025 near Sipaway Island, Philippines. More than 20 colonies spawned four days after full moon, 3.5 hrs after sunset. Gamete release lasted about 30 min and marks the first documented observation of synchronous coral spawning in the Tañon Strait.
Turbid-water reefs present unique ecosystems shaped by complex physical and environmental factors. We conducted standardized benthic surveys in 2023 around Inhaca Island, Mozambique, and integrated these with historical data (1935–2025) to assess long-term changes in turbid-water coral assemblages across a gradient of exposure from a sheltered silty area to a sandy system closer to the open ocean. Of eight historically reported sites, two still showed significant coral cover: the sheltered reef Barreira Vermelha [55.0% (SD 5.0%)] and the semiexposed Ponta Torres Channel [40.7% (SD 8.8%)]. We additionally document a newly formed Acropora field [Ponta Torres New Reef, 64.0% (SD 9.3%)]. In contrast, Portuguese Island Reef was completely buried, and Ponta Rasa showed much lower coral cover with respect to historical baselines [8.1% (SD 3.0%)]. Assemblage composition varied according to the type of dominant sediment: tabular and branching corals prevailed at the sheltered Barreira Vermelha, and massive corals dominated the coarse-sediment reef at Ponta Torres Channel. Although coral cover declined over the past five years, levels at these two main reefs remained comparable to those recorded about 20 years ago, indicating long-term persistence of coral assemblages under chronic turbidity.
The “Bojeo a Cuba” expedition (summer 2023) provided a synoptic, national-scale snapshot of oceanographic conditions around Cuba’s shallow coral reefs during a regional marine heatwave. At 66 sites across six regions, we evaluated key climatic stressors (sea surface temperature, pH, alkalinity) and trophic status indicators. Satellite-derived SST during each site’s sampling week revealed significantly warmer waters on the southern shelf (mean = 30.93 °C) than the northern shelf (mean = 29.21 °C, P < 0.01). In situ SST was consistently high (mean = 30.52 °C), documenting the heatwave’s intensity. pH (mean = 8.12) and total alkalinity (mean = 2343 µmol kg⁻¹) indicated a currently balanced carbonate system. Concentrations of dissolved inorganic nitrogen and phosphorus were below our methods’ quantification limits (1.61 µmol L⁻¹ for P-PO₄³⁻), while chlorophyll-a (mean = 0.04 µg L⁻¹) consistently classified waters as oligotrophic. This study establishes a critical summer baseline, confirming oligotrophic conditions while documenting the severity of thermal stress during the 2023 heatwave—the most immediate and uniform threat to Cuban reefs. Our findings underscore the vulnerability of these ecosystems to extreme warming events within the context of long-term Caribbean warming trends.
Nearshore environments are physically dynamic and critical habitats for marine megafauna, yet they face intense anthropogenic pressures. We used drones to assess seasonal abundances of marine megafauna within Cabuyal Bay in northwest Costa Rica. Between September and February of 2017–2018 and 2018–2019, we flew sawtooth-pattern transects at distances of (1) 0–100 m ( n = 20) and (2) 100–200 m ( n = 16) from the shore. Across 36 surveys, we observed 1889 individual marine megafauna from at least 15 taxa, including eight that are listed as threatened by the IUCN. Grouped into broader categories (rays, bony fishes, reptiles), rays were the most diverse (≥8 taxa) while bony fishes were the most abundant (76% of individuals). Megafauna abundance and species richness, for all taxa except Mobula sp. rays and sea turtles, were significantly higher in the dry season (December–February) than in the wet season (September–November) and positively correlated with wind-driven upwelling and local productivity. Sixty-five percent of all observations occurred within the 0–100 m transects, a pattern mirrored for bony fish (72%) and marine reptiles (70%). In contrast, 62% of ray observations occurred in the 100–200 m transects, largely driven by large aggregations of Pacific cownose rays ( Rhinoptera steindachneri ) in the dry season. Our results indicate that Cabuyal Bay supports high biodiversity and abundance of marine megafauna, particularly rays, and thus we recommend it be considered for local protective measures.
Coral restoration increasingly relies on outplanting branching Acropora species, yet the influence of outplant configuration on early colony performance remains poorly understood. We evaluated whether monoculture vs mixed-species outplantings affect the growth and survival of Acropora parahemprichii and Acropora muricata at a restoration site in Nusa Penida, Indonesia. Coral fragments were transplanted onto artificial reef structures and monitored over a 50-wk period. Both species grew substantially faster when outplanted in monoculture than when grown in mixed-species assemblages, with A . muricata showing the strongest response. In contrast, survival differed between species but did not vary between outplant configurations. These findings indicate that mixed-species outplantings can constrain early colony growth without increasing mortality. Our results demonstrate that spatial configuration is an important factor influencing coral performance during the early stages of restoration. Incorporating monoculture patches to accelerate initial coral cover, alongside mixed-species or genetically diverse assemblages to support longer-term resilience, may improve the effectiveness of coral restoration strategies.
previously fished multispecies aggregation sites provides insight on how to manage them to ensure their continued reproductive success. Riley's Hump is a historically overexploited multispecies aggregation site situated in the no-take Tortugas South Conservation Area, Florida Keys National Marine Sanctuary. This paper summarizes opportunistic observations of a cubera snapper (Lutjanus cyanopterus) aggregation collected from 2011 to 2020. By utilizing a variety of methods, collaborative multi-agency partnerships, and repeated visits to the aggregation site, we gathered indirect (echosounder) and direct (divers, ROV) evidence of significant biomass that persists across multiple months and years, from spring through fall, at the cubera snapper aggregation site. The persistent biomass present at Riley's Hump during known cubera spawning months, color morphs associated with reproduction, and female morphs with visibly distended abdomens, suggests that this location is currently a significant, and likely spawning aggregation site for this species, although direct confirmation of spawning remains to be obtained. In addition to cubera snapper, we confirmed the regular presence of multiple species of apex predators (e.g., Carangidae, Carcharhinidae, Epinephelidae). These observations provide further indirect evidence that the current no-take management designation of Riley's Hump has been successful at maintaining a healthy ecosystem, characterized by snapper, grouper, and other species undertaking critical spawning activities, and higher trophic level species associated with this location and the activities and habitats that occur there. The multispecies spawning aggregations and deep reef habitats of Riley's Hump can serve as a conservation "bright spot" for fish populations in the greater Florida region.
The family Varunidae H. Milne-Edwards, 1853 includes over 180 species worldwide, from tropical to temperate regions. Taiwan is a biodiversity hotspot for varunid crabs, with 22 genera and 46 species, taking up a quarter of the global total species. Given their high species diversity in Taiwan, varunid crabs provide an excellent model for assessing the applicability of DNA barcoding (cytochrome c oxidase subunit I, COI) for species identification and molecular species delimitation. In this study, we obtained COI sequences for 45 species, revealing intraspecific and interspecific genetic distances were 0%-1.86% (0-12 bp) and 5.12%-24.91% (30-138 bp), respectively. Species delimitation, based on morphology and four methods [Automated Barcode Gap Discovery (ABGD), Assemble Species by Automatic Partitioning (ASAP), Poisson Tree Process (PTP), and Multi-rate PTP (mPTP)], indicated that COI reliably distinguished most species except two within the genus Helice. Additionally, the four delimitation methods yielded generally consistent results, with minor discrepancies. Among them, ASAP showed the highest concordance with morphological identification, while ABGD and mPTP underestimated and PTP overestimated species numbers. Our findings show that COI-based species delimitation is effective for most varunid crabs. We recommend using multiple delimitation methods and prioritizing consensus results for robust identification.
Corals are highly sensitive to environmental change, with light and temperature acting as major stressors that disrupt their narrow physiological tolerance. While elevated temperature is a well-established driver of coral bleaching, increasing evidence highlights high irradiance as a critical factor exacerbating stress responses. To elucidate the impacts of environmental factors such as temperature and light on coral physiology and enzyme activity, we conducted an in situ study on Pocillopora acuta from two distinct reef sites in Phuket Province, Thailand, located in the Andaman Sea: Maiton Island (MT), a clear-water reef with higher light level, and Panwa Cape (PW), a turbid reef with lower light levels. Four treatments were involved in the investigation, and the following coral transplants were made: (1) from Maiton Island (NMT) native corals kept at their original reef; (2) corals crossed from Panwa Cape (CMT) to Maiton nursery; (3) from Panwa Cape (NPW) native corals kept at their original reef; and (4) corals crossed from Maiton Island (CPW) to Panwa nursery. Our results show that high light exposure (NMT and CMT) strongly suppressed photochemical efficiency, altered pigment composition, produced excess ROS, which evidenced the photodamage and impaired recovery potential, a history of high light exposure did not confer resilience, as NMT corals exhibited similar stress signatures to transplanted corals (CMT). In contrast, corals in the turbid PW environment (NPW and CPW) maintained more stable photophysiological and biochemical profiles, suggesting that reduced light and higher particulate availability buffered declines in symbiont density and mitigated oxidative pressure. These findings highlight that turbidity may provide a functional refuge by reducing light induced stress. Understanding how corals respond to such local environmental gradients is essential for improving the modeling of bleaching risk and identifying habitats with potential resilience under future ocean change.
Gulf of Mexico (GOM) is a marine ecosystem with high species diversity and provides critical ecosystem services. Nektonic communities support both fisheries and higher trophic level consumers. With potential declines in marine predator populations in the GOM over the past decade, understanding the spatial and temporal dynamics of nekton is critical for ecosystem-based management. We used hierarchical generalized additive models (HGAMs) to investigate the relationship between environmental conditions and the distribution of acoustically detected zooplankton and nekton in the northeastern GOM. We hypothesized that salinity, depth, and distance to bathymetric features are associated with the vertical and horizontal distribution of these organisms. Acoustic data were collected from May to August 2018-2019 and November to December 2018. Pelagic cephalopods exhibited ubiquitous distributions and low relative backscatter, while zooplankton and micronekton had consistently high relative backscatter. Macronekton showed significantly higher backscatter, with the maximum backscatter being up to 2600 times greater than pelagic cephalopods. Macronekton also exhibited significant variation in depth distribution, with increasing backscatter below 200 m, and showed different vertical movements in response to the diel cycle. Each acoustic class responded uniquely to environmental conditions, underscoring the complexity of zooplankton and nekton distributions in the GOM. We offer recommendations for future studies, particularly for incorporating additional environmental and seasonal variables. Overall, our research improves understanding of how zooplankton and nekton in the northern GOM respond to environmental variability, informing ecosystem dynamics and pelagic food web structure.
A large-scale and unprecedented population of Galaxea paucisepta was discovered in Sandy Lagoon at Beijiao Reef (Paracel Islands, northern South China Sea). Their colonies formed extensive foliaceous frameworks, exhibiting morphology adapted for shedding sediment in this stable, wave-sheltered environment, highlighting the role of lagoons as critical coral refugia.
.-Vampyroteuthis infernalis is an enigmatic cephalopod that has garnered attention due to its morphology, behavior, and adaptations to life below 600 m in the world oceans. Qiu et al. (2024) reported on a novel Vampyroteuthis species from the South China Sea based on one adult female. In their phylogenetic and morphological analysis, they included specimens from the Gulf of Mexico (GoM) and suggested they belong to the new species. Here, we reexamined the morphology of GoM specimens, reran the Qiu et al. (2024) phylogenetic trees using the same dataset (COI, 18S rRNA, 28S rRNA; single-gene trees), and built new phylogenetic trees (added 16S rRNA and concatenated trees) to investigate the validity of "V. pseudoinfernalis". Our results do not support "V. pseudoinfernalis" as a novel species but a synonym to V. infernalis. While there is likely intraspecific variation within the vampire squids, morphological characters such as the acute tail and the broad elongate wing of the lower beak were not observed from the GoM specimens. None of the phylogenetic trees support "V. pseudoinfernalis" as a distinct species. A suggestion is to collect additional V. infernalis samples from the South China Sea to examine the possibility of intraspecific variation.
