A San Blas skate (Dipturus garricki) was incidentally captured at a depth of ~284m in the Guatemalan Caribbean Sea, ca. 11km northeast of El Quetzalito. The immature female with a total length of 742mm and disc width of 610mm had morphological characteristics consistent with Dipturus garricki. This is the first record of this little-known skate in the western Caribbean region. This new record is significant due to the scarcity of records of this species along its distribution in the Western Atlantic (N = 19).
Bottom friction is one of the factors that shape how energy, heat, and salt are distributed in marine basins. This study investigates the Adriatic Sea using ROMS ocean model simulations with varying quadratic drag coefficients (Cd = 0.001–0.003) to assess how bottom friction intensity affects circulation, temperature, salinity, and turbulence. Higher drag reduces near-bed temperature by up to 1.5 °C and salinity by up to 1 PSU, increases bottom stress by 0.05N/m², and raises sea surface height by up to 1.5cm in the southern basin due to less water exchange with the Ionian Sea. Kinetic energy dissipation in the bottom layer reaches 80% compared to the frictionless case. By restricting the inflow of warm, saline Ionian water and limiting freshwater outflow from the Adriatic Sea, stronger friction promotes retention of cooler, less saline water throughout the basin — consistently across all sub-basins. Although higher drag amplifies near-bed turbulence, seasonal stratification prevents this signal from penetrating the upper water column. Bottom friction therefore controls turbulence generation, while stratification governs its vertical reach — an interplay critical for understanding benthic–pelagic exchange. Accurate drag parameterisation is essential for reliable Adriatic circulation modelling and has direct implications for regional marine and climate forecasting.
Sandy beach surf zones are dynamic environments where physical processes interact with biological communities. Coastal hydrodynamics influence beach morphodynamics and sediment characteristics, which in turn shape benthic communities and associated trophic levels. Moreover, surf zones provide essential nursery and refuge habitats for many fish species, highlighting the importance of understanding the environmental factors driving community structure in these ecosystems. In this study, we investigated the surf-zone communities of four sandy beaches located in the Ría de Vigo (Galicia, Spain), including two beaches on the northern and two on the southern side of the Ría. We investigated beach morphodynamics, including sediment granulometry and beach profile, macrofaunal communities, and fish assemblages to evaluate differences among beaches. We observed significant differences among beaches across the biological and environmental variables studied. In addition, fish assemblage composition showed spatial segregation, with Liméns beach, located on the northern side of the Ría, forming a distinct cluster, while also being the beach with different sediment characteristics. This separation was mainly related to differences in species composition, including the absence of Pegusa lascaris and Echiichthys vipera in this beach.
Ozone depletion has led to increasing levels of ultraviolet radiation (UVR) reaching the Earth’s surface, with sublittoral macroalgae predicted to be particularly vulnerable due to their adaptation to stable light environments. This study investigated the physiological responses of the sublittoral red macroalga Laurencia obtusa to three irradiance treatments- PAR (P), PAR+UVA (PA), PAR+UVA+UVB (PAB) – applied over three weeks, followed by a one-week recovery period. UVR stimulated the synthesis of chlorophyll-a, phycobiliproteins and UV-absorbing compounds, while nitrate reductase activity was significantly elevated under both UV treatments relative to PAR alone. Despite increased nitrogen assimilation, neither growth rate nor protein content increased under UV exposure, suggesting that assimilated nitrogen was preferentially directed towards the synthesis of photoprotective compounds. The persistence of elevated pigment contents, UV-absorbing compound levels and nitrate reductase activity during the recovery period indicates that the physiological effects of UVR were not reversed within one week. Overall, L. obtusa maintained its growth performance throughout the experiment, demonstrating that this sublittoral species possesses sufficient photoprotective capacity to tolerate sustained UV exposure. These results suggest that L. obtusa retains sufficient physiological capacity to tolerate an acute, field-realistic surface-level UVB dose, despite naturally inhabiting a UVB-attenuated sublittoral environment in the Marmara Sea.
Despite widespread adoption of satellite-derived shorelines (SDS) for coastal-change monitoring, inference from public Earth observation (EO) archives is rarely tested against the noise floor imposed by the full measurement chain. Positional accuracy is routinely reported, but whether observed geomorphic trends exceed accumulated tidal, wave-runup, and registration uncertainty remains largely unverified. This study develops a signal-to-noise (SNR) detectability framework for microtidal, mixed-energy tropical coasts using decadal Landsat 7/8/9 and Sentinel-2 imagery, 454 beach-profile surveys, and Digital Shoreline Analysis System (DSAS) version 6.0 shoreline-change metrics across five beaches in Trinidad and Tobago. The framework evaluates geomorphic change against positional, tidal, and wave-runup noise and classifies site behaviour into robust (SNR > 1.5), marginal (0.5–1.5), and low (< 0.5) detectability regimes. Validation against 344 profile-matched observations produced a pooled root-mean-square error (RMSE) of 15.1m, decreasing to 10.5m at three well-calibrated sites. Error separated into an elevation-dependent component reducible by contour calibration and a registration-limited component that persisted across contour choices. Optimum contours grouped at two elevations, −0.2m relative to mean sea level (MSL) at Irois and Turtle and +0.5m MSL at the remaining sites, an indicative association with foreshore slope and wave forcing rather than arbitrary tuning. Only Irois was clearly signal-dominated (SNR = 2.74); the remaining four sites were marginal, and two of them (Turtle and Las Cuevas) showed directional instability, including 82.7% transect-level End Point Rate (EPR) - Linear Regression Rate (LRR) sign reversal at Turtle Beach. Runup-based SNR at the two registration-limited sites (Kilgwin and Mayaro) is an upper bound; against a combined noise floor that adds the systematic registration bias in quadrature, Kilgwin falls to low detectability (SNR = 0.45) while all other classes are unchanged. No site was simultaneously robust, well calibrated, and directionally coherent. Defensible SDS-based coastal-change inference therefore requires explicit testing that the geomorphic signal exceeds the site-specific noise floor, not positional accuracy alone.
Since the 1980s, sea surface temperature in the Persian Gulf has increased at a statistically significant rate of approximately 0.004 °C per month (p<0.01), superimposed on a pronounced seasonal cycle and consistent with the global warming trend. This warming poses substantial risks to the fragile marine ecosystem of the Persian Gulf. Using daily sea surface temperature data from January 1982 to December 2024 and applying the standard hierarchical marine heatwave detection framework, this study examined the characteristics and trends of marine heatwaves in the region. Empirical Orthogonal Function analysis was employed to identify the dominant spatial patterns and temporal modes of marine heatwaves variability across the Persian Gulf. The results reveal a significant increase in the duration, and intensity and rather the frequency of marine heatwaves over the past decades. More than 335 severe marine heatwave events were recorded between 1993 and 2024. The El Niño–Southern Oscillation index showed a strong statistical association with marine heatwaves occurrence and intensity through global-scale teleconnection patterns, with particularly notable correspondence during specific years, such as 2018. Coral bleaching events were predominantly linked to the El Niño, underscoring the interconnectedness between large-scale climate drivers and local marine ecosystem health.
