Marine Biology最新文献

Worldwide, seabird populations are facing significant declines due to various threats, making them valuable bioindicators of marine ecosystem changes. Understanding their foraging behavior and identifying crucial foraging areas (FAs) is essential for their conservation. In this study, the focus was on Olrog’s gull (Larus atlanticus), a near-threatened species endemic to the Atlantic coast of Argentina, Uruguay, and southern Brazil. The objectives were to assess the distribution of FAs and home ranges of Olrog’s gull and to evaluate the overlap between FAs and protected areas (PAs) in the Bahía Blanca Estuary (BBE), Argentina. Global positioning system (GPS) tracking and dynamic Brownian bridge movement models (dBBMM) were used to analyze Olrog’s gull behavior during their breeding season. The results revealed well-defined FAs, with 72% of them located outside PAs, raising concerns about potential threats to the species. Sex-related differences were observed, with females covering longer distances during foraging flights. In addition, several FAs were located near industrial sites, posing health risks due to pollution. This study contributes novel insights into Olrog’s gull foraging ecology, particularly in the most critical breeding area for the species. A dynamic web application was developed to provide rapid access to comprehensive information applicable to conservation actions. These findings underscore the need for enhanced protection of critical FAs, particularly those lying outside currently PAs.

This research emphasizes the importance of well-informed policy decisions to enhance ongoing conservation initiatives for Olrog’s gull populations and their habitats, particularly in the face of increasing threats posed by human activities.

The right third arm of the male octopus is the hectocotylized arm. This arm is modified by anatomy specialized to hold and transfer sperm packets to the female, and lacks suckers at the distal end. Male octopus may be distinguished by the skilled eye from their habit of holding their hectocotylus closer to their body in a protective manner, although this observation has never been described quantitatively. We utilized a three-step process of data annotation, pose estimation model training, and model inference to show that this common observation is true of Octopus rubescens. In 2338 images, the eyes, mantle tip, and arm tips of two male (n = 1152) and three female (n = 1085) octopuses were annotated by an experimenter. These images were then used to train a DeepLabCut pose estimation model which achieved a RMSE of 1.78 cm. This model was then used to annotate 11.4 h (n = 408,985 images) of four female and eight male octopuses moving across the middle of a large aquarium. We then compared the human annotated data, and the model inference data separately. In both datasets we compared the arm-tip-to-eye centered point distances, as well as the octopus centric arm tip 90% kernel density estimation area. In both the training dataset and the model inference datasets we found common results. Male O. rubescens hold their third to the right arm closer to their body than all seven other arms while the females do not. Further, in both males and females, the rear arm pairs operate closer to the body than the front arm pairs. Despite their anatomical similarity and potential redundancy, these results indicates functional differences in arm use by octopuses.

Abstract

Thermal conditions in the nest affect the development of sea turtle clutches, with high temperatures potentially reducing reproductive success and the quality of hatchlings. In a warming climate, increasing temperatures could become a threat to sea turtles in many locations. This has prompted the implementation or recommendation of climate mitigation strategies in nests that incubate in hatchery conditions. Here, olive ridley turtle (Lepidochelys olivacea) clutches relocated to a beach hatchery in Playa Grande, Costa Rica (10° 20 N, 85° 51 W) were used to study the effect of temperature on hatching success and hatchling size. Data from 5 nesting seasons (2017/18 to 2022/23, excluding 2020/21) were tested to determine the effect of mean incubation temperature by thirds of development, as well as over the whole incubation period. Hatching success was lower at low and high temperatures and higher at intermediate ones during the second and last thirds of development. Optimal mean temperature ranges were 29–32 °C and 32–35 °C across the second and last thirds of development respectively, and 30–32.5 °C during the whole incubation period. There was no statistically significant effect of temperature on hatching success during the first third of development. High temperature resulted in shorter carapace width but did not statistically affect mass or carapace length. The temperature effect on carapace width occurred in all thirds of development. Studying temperature effects on target species nests at the local level, throughout incubation, and over multiple years is important for applying climate mitigation strategies properly.

In order to address lack of data regarding coastal carbon budgets, we estimated the annual metabolic carbon budget of an intertidal rocky reef macroalgal community during emersion. This budget is based on direct in situ measurements during emersion and establishes the seasonal variations of the photosynthetic parameters of such a community. CO₂ fluxes were measured hourly to study the response of community gross primary productivity (GPP) to irradiance and the variation of GPP and community respiration (CR) over the emersion period at different times of the year. These were combined together with existing monthly measures of GPP and CR hourly rates to model the variations of these fluxes as a function of irradiance and the tidal cycle throughout an entire calendar year. Daily, monthly and annual values of GPP, CR and net primary productivity (NPP) were calculated with a relatively low sensitivity to any of the parameters used. While GPP fluxes show comparable orders of magnitude to those measured in other systems, higher CR fluxes lead to a heterotrophic system during emersion, both under measured (NPP = −299 gC m⁻² year⁻¹) and theoretical irradiances (NPP = −119 gC m⁻² year⁻¹). This heterotrophy is directly linked to the light availability, varying according to combined daily, tidal and seasonal cycles, and to temperature at the seasonal scale. Measurements performed in situ at the community scale integrated interactions that are otherwise absent at the individual scale. This gives access to aspects of the functioning that cannot be otherwise identified.

Abstract

Brazil’s second-largest reproductive colony of loggerhead turtles (Caretta caretta) has a long history of overexploitation, with its temporal ecological dynamics still unknown. This study investigates changes in the average size of females and post-maturity somatic growth rates in marked and recaptured loggerhead turtles at a breeding site over a 33-year period (1982–2014). Loggerhead curved carapace length (CCL) was evaluated over the course of the study using a generalized additive model (GAM) with a Gaussian family distribution and time smoothed. Includes the nesting year and the CCL for a total of 2.359 female loggerhead turtles. The overall average length of females was 99.4 cm ± 5.8 (mean ± SD). The results suggest that the CCL of females in the nesting area is decreasing. From 1982 to 1998, the mean CCL was 102.6 cm; from 1999 to 2014, the average length was 98.7 cm. There were no statistically significant differences in post-maturity growth rates among recaptured females, supporting the hypothesis of increased recruitment. The GAM results showed significant differences in the size structure changes of reproductive site females over time. The study highlights how a population parameter can be influenced by long-term conservation of feeding and nesting areas for sea turtles, resulting in a higher number of recruits. The curved carapace length serves as an important metric to describe population changes and raise awareness about future conservation challenges.

Understanding natural movement patterns and ecological roles of marine megafauna is a research priority best studied in areas with minimal human impact. The spatial distribution patterns specifically for immature turtles at foraging grounds have been highlighted as a research gap for effective management and conservation strategies for sea turtle populations. Capture–mark–recapture (CMR) records (n = 2287) of 1672 immature green (Chelonia mydas) (n = 1158) and hawksbill turtles (Eretmochelys imbricata) (n = 514) from a long-term (1981–2021) in-water CMR program at Aldabra Atoll, Seychelles, were analyzed for 10 sites (0.35–25 km apart). Site fidelity was not correlated with either season or turtle size. Green turtles had lower site fidelity than hawksbill turtles. Green turtles showed avoidance (i.e., opposite of fidelity) of three sites, while hawksbill turtles displayed high fidelity to two sites. Sites displaying non-random behavior (avoidance and/or fidelity) did not share the same benthic habitat types. Results indicate that fidelity can be detected at a fine scale with CMR, but that further exploration into the habitat characteristics of the sites and the ecological roles of both species at the atoll is needed.

Fan mussel (Pinna nobilis) is one of the largest bivalve species in the Mediterranean Sea. The situation of the species is critical as it faces widespread mass mortality attributed to pathogens in various parts of the Mediterranean Sea. The Sea of Marmara (SoM) offers a unique environment for fan mussel populations, with some areas hosting alive populations. This study aims to explore and describe new P. nobilis populations in the SoM that are known to be not affected by mortality. An area of 28,200 m² at 47 stations along the 105 km coastline in the southern part of the SoM was explored using underwater visual transects. A total of 544 alive fan mussels were recorded during the underwater surveys, ranging in total shell height from 11.8 to 31.4 cm. The mean density was estimated as 5.3 ind 100 m⁻² although maxima of 18.8 ind 100 m⁻² were recorded in some stations. These density hotspots were distributed from the shoreline to a 10 m depth range and 100 m distance from the shoreline in sandy and seagrass meadow habitats. The presence of juveniles provided evidence of successful recruitment. The distribution pattern and recorded mortalities were attributed to hydrodynamic factors and intense human activities. Potential environmental factors (low salinity and temperature) in the SoM may control or delay the possible spread of the lethal pathogens. Favorable conditions result in mussels’ resilience and survival mechanisms. The SoM offer a promising larval reservoir for the recolonization of affected areas, such as those found in the Aegean Sea, through larval exportation.

Knowledge of recruitment to a fishery is particularly important in short-lived species, like most cephalopods, in which there is a complete turnover of individual every 1 or 2 years. In this study, age, body length, statolith length and growth rates of loliginid paralarvae (Alloteuthis media, A. subulata and Loligo vulgaris) were determined to evaluate the form of the growth curve and differences between species and hatching seasons. A total of 222 paralarvae collected in zooplankton samples along the Galician coast (NW Spain) were used to determine relationships between dorsal mantle length (DML), statolith length (SL) and the number of increments (NI)) deposited in the statolith. The paralarvae of L. vulgaris were between 1 and 35 days old, while both Alloteuthis species ranged in age from 1 to 54 days. Generalised additive models (GAMs) revealed non-linear growth in DML, with L. vulgaris exhibiting higher DML-at-age than Alloteuthis species. The best parametric model fit for these data was obtained using exponential regressions. The SL–NI relationship also differed between species, with L. vulgaris having larger statolith length at age. The paralarvae of L. vulgaris and A. media had two well-differentiated hatching peaks, one in late spring-early summer (beginning of the upwelling season) and another peak in late autumn (end of the upwelling season). Alloteuthis subulata had an earlier hatching peak in spring than in the other two loliginid species—and the second peak in autumn was barely visible, possibly because this species occurs further north in areas not sampled in autumn.

Antipatharians are conspicuous habitat-forming coral species in shallow, mesophotic and deep sea environments worldwide. Despite their ecological importance, very little is known about their early life stages. In this study, we provide the first detailed description of the embryo and larval biology of the antipatharian coral species Antipathella wollastoni. Embryos were reared in aquaria, allowing observations of the embryo development, embryo and larval survival, as well as larval swimming behavior of the species. After gametes were released into the water column, fertilized oocytes developed into planktotrophic planulae within 48 h. Embryo and larval mortality was high, and median survival was 12–18 h. Larvae were active swimmers, with an average swimming speed of 0.35 ± 0.12 mm s⁻¹. These larval characteristics contradict previous descriptions of antipatharian larvae that report non-feeding, crawling larvae, therefore further studies are imperative to better understand early life processes in this taxonomic order.