Marine Ecology-An Evolutionary Perspective最新文献

Tool use is a remarkable animal behaviour, and the investigation of this phenomenon in fishes is a relatively new and growing field. The graphic tuskfish Choerodon graphicus (De Vis 1885) has previously been documented using anvils but the extent and variability of this tool-use behaviour remains poorly understood. In this study, we investigated whether C. graphicus breaks open crustaceans and/or sea urchins on anvils in different microhabitats and/or locations. We also inspected two previously identified anvils for evidence of long-term anvil use. Three individual C. graphicus were observed breaking open sea urchins on dead coral anvils in a coral rubble microhabitat at Île aux Canards, New Caledonia. They produced visual and auditory cues while carrying out tool-use behaviour and these cues often attracted attendant fishes. Notably, two anvils appeared to have been used by one or more tool-using C. graphicus for years at Îlot Maître, New Caledonia. These findings suggest that tool-use behaviour is both innate and learned and is a prey-handling method of choice used by individuals that learn to specialise in large prey items from a few underutilised hard-shelled prey species. Furthermore, the findings show that specific anvils can be used long-term and also suggest that individual wrasses may carry out tool-use behaviour long-term. The study provides new insights into the feeding ecology and social behaviour of C. graphicus and underscores the need to further investigate the extent and variability of tool use in fishes.

Nancite is a fully protected beach within the Guanacaste Conservation Area, Costa Rica where olive ridley (Lepidochelys olivacea) sea turtles nest in synchronous mass-nesting events known as arribadas. Arribadas decreased in magnitude at this beach by approximately 90% during the period 1971–2007 due to unknown causes. The total count estimate of females nesting in a year also decreased over these decades. In the present study, from August 2009 to February 2021, the trend of arribada nesting female abundance and estimated annual production of hatchlings were assessed and compared with previous trend analyses. A total of 62 mass-nesting events were quantified in the period 2009–2021, with an estimated annual average of 64,694 nesting females. Trend analysis indicated that during our recent study period, the number of females per arribada event increased by an estimated 14% (8%, 20% CI_95%). During this period, a mean hatching rate of 33.4% was estimated, corresponding to an overall estimated production average of 2,165,597 per season, which represented an increase of 82.7% compared with a previous estimate for the period 1980–1984, when the arribadas were larger. We suggest that the growth in hatchling production over the past four decades is at least in part responsible for the slight increase in the estimated size of arribadas since 2009/2010. However, because maximal hatching success did not increase above 60%, the beach may be close to reaching carrying capacity, and it seems that high hatchling production may soon level off or begin to decrease. Thus, it is not clear whether current hatchling production will lead to the recovery of the Nancite population to the historical levels documented in the 1970s and early 1980s.

Population dynamics of invasive species and their impacts on native communities vary substantially geographically and in different environmental contexts. Therefore, effective management of invasive species requires understanding how habitat characteristics, anthropogenic effects, or other perturbations can influence their abundance and impacts on native communities at multiple spatial and temporal scales. This is particularly challenging when geographically widespread, long-term data are lacking. The Asian shore crab, Hemigrapsus sanguineus, is a well-studied invader on the Atlantic North American coast. A few studies suggest that its populations may be declining in parts of its introduced range, but spatial variation in its population dynamics is considerable even among geographically proximal habitats. We explore the ability of habitat characteristics and prey availability to predict abundance of the Asian shore crab at 12 rocky intertidal sites in southern New England over 5 years (2014–2018). Overall, abundance of the Asian shore crab increased non-linearly with time, with the rate of increase declining over time, but abundance varied among sites and population dynamics were spatially asynchronous. Aspects of habitat complexity and disturbance strongly contributed to variation in abundance, but the most important predictors reflected complex and non-linear interactions among sea surface temperature, latitude, and prey abundance. The influence of prey abundance and latitude on crab abundance were modulated by the survey years, which underscores the importance of temporal variation in mediating the species–habitat relationship. Uncovering such intricate dynamics warrants long-term data on population trends and impacts of invasive species, geographically replicated at multiple sites to capture regional heterogeneity.

Avoiding recognition involves the use of extraordinary strategies, among which camouflage is the most common. Crypsis, a usual form of camouflage, involves, among many other strategies, disruptive coloration that uses marks that disguise the contours of creatures to hide it. Fish that live on coral reefs have developed several cryptic strategies to avoid the risk of detection. The blue-spotted cornetfish, Fistularia commersonii, presents a pattern of dark bands that give the perception of disruptive coloration; however, this strategy has not been characterized for this fish. This study was conducted on the eastern coral reefs of Gorgona Island National Natural Park (Colombia). To confirm whether F. commersonii presents a disruptive pattern, photographs, and videos in situ of the individuals were taken, in addition to recording aspects of their behavior during changes in coloration. After strict selection, different images were processed and evaluated using three different visual systems (potential predator, potential prey, and human) to calculate the GabRat metric, that is detect consistent to inconsistent edges of a pattern. The images analysed and the observations indicate that this species displays a disruptive pattern that is used more frequently in the reef flat and during alert states, either in the presence of a possible predator or during the search for food.

The present study investigated whether temperate wrasses in a geographical location in the southern hemisphere break open crab prey on anvils. Here, tool-use behaviour is reported in two temperate wrasses, the orange wrasse Pseudolabrus luculentus and the doubleheader Coris bulbifrons, at Lord Howe Island, Australia. In addition to the previous observations of this behaviour, these findings suggest that tool use is common and may be ubiquitous, in medium-sized carnivorous wrasses that are undergoing an ontogenetic shift from soft-bodied to hard-shelled prey.