Marine Biology最新文献

Group living is widespread and beneficial to metazoans. It improves protection and survival opportunities, reinforcing interspecific competitiveness. Benthic cnidarians often colonize large surfaces. Evidence of collective capture and exploitation of large prey by small, clumped polyps suggests that aggregation is functional to access food resources hardly achievable by isolated individuals. In turn, the chance to catch large prey may represents a driver of aggregation in polyps, whether beneficial to their fitness. Here, the effects of group foraging on aggregation, asexual reproduction, and growth rates of Aurelia coerulea von Lendenfeld 1884 polyps were experimentally tested by providing them with either small or large prey, or a mix of both to simulate the co-occurrence of preys at sea. As expected, some polyps were not able to reach the large prey. Hence, the population was a posteriori divided into group-foragers and solitary-feeders. In general, the large prey diet resulted in higher population fitness and when simultaneously supplied with the small prey represented an energetic booster resulting beneficial for all group-members. The decrease of interindividual distances was reported among group-foragers, that converged towards each other. Cnidarians are basal in metazoan evolution, and the comprehension of their collective foraging behavior, as well as the processes leading to the selective feature driving them to forage in group or not, may be essential to better understand the evolution and spread of social foraging in animals. Moreover, the access to large prey by sessile polyps of Aurelia coerulea could be pivotal in determining the increase in abundance of adult bloom-forming medusae.

Museum specimens preserve genetic information that can help resolve phylogenetic relationships of now extinct species. The Caribbean monk seal, Neomonachus tropicalis, is the only marine mammal driven to extinction in tropical seas and one of the few marine mammals to go extinct in historical times. Prior to 1700 it was widely distributed throughout the coasts of North, Central and South America, and in the Bahamas, Greater and Lesser Antilles. The species was first taxonomically placed in the genus Monachus, along with the Hawaiian and Mediterranean monk seals and it was later moved together with the Hawaiian monk seal into the newly described genus Neomonachus. Here, we present the complete mitochondrial genome of the Caribbean monk seal and a phylogenetic reconstruction, confirming its sister taxa relationship with the Hawaiian monk seal, and thus the monophyly of the genus Neomonachus. Our estimates of divergence times are contemporaneous with or predate the emergence of the Isthmus of Panama. We also identify limited genetic variation among five specimens of Caribbean monk seal.

Predation is a key process that influences the structure and functioning of ecosystems. Tethering experiments, which involve restraining prey or prey analogs in field settings, are used to evaluate predation with minimal manipulation of predators and the environment. However, tethering experiments alter the behavior of mobile prey, an issue that increases in severity with prey mobility and reliance on that mobility to evade predators, resulting in artifacts that complicate the interpretation of experimental findings. Given their widespread and rapidly evolving use, we review and reconsider the applications of tethering experiments in marine ecosystems, their utility in measuring predation, associated artifacts, theoretical, methodological, and statistical considerations and challenges, and how to overcome these. Breaking down the predation process into its successive stages (encounter, attack, capture, and consumption), we consider that tethering experiments effectively measure two major aspects of predation: (1) relative predation rates (requiring all four stages, and resulting in successful predation) and (2) predation risk (requiring only encounter and attack). We suggest that tethering experiments be designed to test hypotheses that target particular stages or all stages of the predation process and its drivers, through manipulating tethering experimental designs, conducting direct observations of tethering experiments, collecting additional community or environmental data, combining tethering with other experimental approaches, and through statistical analyses. This general approach facilitates both our understanding of the limitations and utility of tethering experiments to compare patterns and identify drivers of predation rates and risk in the field, topics of study that remain underrepresented in the literature.

Climate change may impact individual organisms in different ways, a consideration often overshadowed by predominant focus on population effects in studies. We examined three estuarine fish species to determine if individual fish performance, persisted across winter water temperatures. Fish performance at 16 °C (current Sydney winter estuarine water temperature) and 20 °C (predicted under climate change) with low and high food regimes was assessed using key physiological (growth, aerobic scope, burst speed) and behavioural parameters (foraging activity, boldness, shelter usage, predator escape response). We expected a strong positive relationship between performance at 16 °C and 20 °C for each parameter, and interactions with food level, however in general this was not found for any species. Relative performance was only maintained across temperatures for a few parameters, such as bite rate, boldness, and shelter response in one species (trumpeter Pelates sexlineatus), with aerobic scope in silver biddy Gerres subfasciatus, and boldness in fortescue Centropogon australis. Our results suggest that individuals’ fitness (directly via changes in growth, indirectly via behaviours) might be impacted by climate warming due to differences in relative performance among juvenile individuals across water temperatures. Changes in relative performance among individuals may initially compensate for a population-level response, thereby buffering the effects of climate change.

Marine Heat Waves (MHWs) occurrence has been increasing in the Mediterranean Sea. The effects of field simulated MHWs of different intensity (medium and high temperature) on the transcriptome expression of the endemic seagrass Posidonia oceanica were evaluated considering different origins of the plant. The aim of the study was reached through a common garden transplant experiment in the North-west of Sardinia (Italy), where two P. oceanica meadows characterized by different thermal regimes (cold and warm) were chosen. MHWs were simulated in front of a power plant, that creates a natural laboratory by releasing warm water in the sea. Differential gene expression and GO enrichment analyses highlighted differences in the transcriptomic profiles of plants from cold and warm environments suggesting that the MHWs induced different levels of stress due to different tolerance to the heat event. Plants from both origins activated processes to achieve protein homeostasis, but only cold plants activated an antioxidant defense and altered sugar metabolism, both indicators of heat stress. Within plants of the same origin, a different response to MHW intensity was also detected: while warm plants showed the most complex response at high temperature rather than at medium temperature, cold plants seemed to better cope with the medium temperature intensity rather than with high temperature.

The nature of symbiotic relationships between organisms can be difficult to assess and may range from commensalism, to mutualism, and parasitism. Trophic linkage and feeding ecology are essential to disentangle symbiont-host relationships/interactions. Amphipods of the genus Dactylopleustes are known as urchin symbionts. Though their ecology remains largely unknown, Dactylopleustes was recently reported to aggregate on diseased hosts, suggesting that Dactylopleustes feeds on diseased urchins’ tissues and uses urchins as both a habitat and prey. We investigated by DNA metabarcoding analyses, the feeding ecology of Dactylopleustes yoshimurai in relation to growth and disease status of the host (Strongylocentrotus intermedius). Contrary to our hypothesis, sequence reads from the gut contents were dominated by planktonic copepods regardless of body size or host disease status. These results suggest that they mainly feed on copepod fecal pellets deposited on sediments, and do not have a strong trophic linkage with their host. Large individuals on diseased urchins feed more on urchins than those on healthy urchins. However, their main prey still remains copepods, implying that host disease has a limited effect on the feeding behavior. In conclusion, our study indicates that this species is mainly commensal, but also may parasitize its host depending on the situation.

A comprehensive survey of the octopus fauna around the Americas is presented to facilitate and accelerate the assessment of a full understanding of American octopus biodiversity. Brief accounts are provided summarizing research efforts on octopus species taxonomy, diversity and distribution in different regions of North and South America. Octopus americanus and O. insularis are compared and clearly distinguished from each other and from the closely-related European species, O. vulgaris. The use of genus names Paroctopus and Pinnoctopus is clarified. Included is a discussion of the recent application of genus name Paroctopus to warm-temperate and tropical species of small size, along with a cautionary note about species identifications in the light of past errors in misassigning large-to-giant cold-water species to genus Paroctopus. Related to problems with identifying species of Paroctopus, there is an appended note concerning misidentifications and the importance of thorough species descriptions to obtain species information at the levels of both phenotype and genotype. A lectotype is formally designated for Bathypolypus arcticus (Prosch, 1849); and the status of so-called ‘Octopus giganteus’ is reviewed briefly. A supplementary online database, AmeriCeph, provides basic information about all known octopus species of the Americas, including the institutional location of type material and the identification of voucher specimens and their depositories. DNA sequences registered in this database are not all fully compatible with barcoding standards. However, a subset of DNA sequences conforming to strict barcode identifications is provided in a second supplementary table, providing barcode sequences directly applicable also to improving standards of seafood traceability. This in turn contributes to building sustainability of exploited octopus fisheries stocks and identification of species suitable for aquaculture trials to meet the increasing commercial demand for octopus worldwide.

Offshore windfarms are a potential threat to seabirds, partly due to collision risk with turbine blades. Wind influences the mode, height and speed of seabird flight, and therefore the risk of collision with turbines. We investigated how wind influences the flight of black-legged kittiwakes Rissa tridactyla, a gull of conservation concern, in order to incorporate these findings into collision risk estimates and identify mitigation measures. We used GPS telemetry data (23rd June to 10th August 2021) from 20 kittiwakes breeding in Aberdeenshire, UK (57.385°N, 1.868°W) to estimate the effect of wind on behavioural state, proportion of flight at collision risk height, probability of collision when within the rotor-swept zone, and overall collision risk. We found that as windspeed increased, kittiwakes commuted less and rested more. With increasing windspeed, kittiwakes spent a considerably smaller proportion of their flight time in the rotor-swept zone, but had a slightly higher probability of collision while in it. Uncertainty was high for most relationships between windspeed and kittiwake flight metrics. The overall effect of increasing windspeed on collision risk was negative, although we did not model avoidance rate. Effects of windspeed on collision risk were largely mediated through effects on commuting flight, and contingent on wind direction. Collision risk estimates incorporating the effects of windspeed may have greater precision and accuracy, but considerable uncertainty in windspeed-flight parameter relationships remains. Therefore although kittiwake collision risk may be mitigated by raising the ‘cut-in’ windspeed above which wind turbines generate power, the magnitude of this effect is uncertain.

Seabirds are among the most threatened avian taxa. Effective seabird conservation requires an understanding of both seabird distributions and habitat usage. Species distribution models can help identify important areas for protection and manage threats to seabird populations. However, populations of the same species may differ in their response to the environment, reducing the transferability of such models. In addition, individual-level responses to habitat may vary both within and between animal populations. Atlantic Puffins (Fratercula arctica) are classed as vulnerable to global extinction and a UK red-listed bird of concern. Consequently, a greater understanding of their at-sea habitat usage is a conservation priority. We used GPS tracking data from four UK Puffin colonies to construct species distribution models and examine colony- and individual-level variation in habitat usage in response to a suite of environmental covariates (chlorophyll-a concentration, sea surface temperature (SST), water depth, seabed slope, current velocity, and SST front gradient). The most consistent colony-level response was a negative association between habitat usage and chlorophyll-a concentration (observed at 3 out of 4 colonies). Responses to other environmental covariates were less consistent across colonies. Among individual variation in foraging range per trip was low, but we observed individual variation in habitat usage in response to almost all environmental covariates examined. Within each colony, we also identified distinct clusters of space-use across different groups of individuals. Different Puffin colonies and individuals are not ecologically equivalent. Therefore, perturbations to the marine environment are likely to have disproportionate effects on certain colonies and/or individuals. Incorporating colony- and individual-level variation will thus be essential for marine conservation efforts.

Coral calcification is critical for reef growth and highly dependent on environmental conditions. Yet, little is known about how corals calcify under sub-optimal conditions (e.g., turbid waters, high nutrients, sedimentation) or coral growth in understudied regions such as the Colombian Caribbean. We therefore assessed the calcification and linear extension rates of five coral species across an inshore-to-offshore gradient in the Colombian Caribbean. A suite of environmental variables (temperature, light intensity, visibility, pH, nutrients) measured during the rainy season (May – November 2022) demonstrated more sub-optimal conditions inshore compared to offshore. Across all species, calcification rates were 59% and 37% lower inshore compared to the offshore and midshore sites, respectively. Across all sites, massive corals calcified up to 92% more than branching species but were more susceptible to heat stress and sub-optimal inshore conditions. However, branching species had reduced survival due to extreme climatic events (i.e., bleaching, hurricanes). A comparison with published rates for the wider Caribbean revealed that massive species in the Colombian Caribbean grow up to 11 times more than those in the wider Caribbean while branching species generally have similar growth rates, but this finding may have been influenced by fragment size and/or heat stress. Our findings indicate that present-day environmental conditions, coupled with more frequent extreme climatic events, will favor massive over branching species in midshore areas of the Colombian Caribbean. This suggests a possible shift towards faster calcifying massive species in future coral communities, possibly exacerbating the ongoing regional decline in branching species over the last decades.