查看更多>>摘要：In the context of ongoing outbreaks of the crown-of-thorns starfish, the outbreak of the South China Sea's crown- of-thorns starfish (Acanthaster solaris) has severely threatened coral reef ecosystems, highlighting the urgent need for research on related control and eradication technologies. Biological control offers environmental friendliness and long-term effectiveness, making research on predator fish species crucial for managing the crown-of-thorns starfish outbreaks. This study investigates the feeding effects of seven common coral reef fish species in the South China Sea on crown-of-thorns starfish larvae, aiming to identify suitable predator fish species for South China Sea reefs. Additionally, the study develops and validates eDNA quantitative detection technology for the most effective predator, providing technical support and data for subsequent stock enhancement, release effectiveness evaluation, and fishery management. The results indicate that Pomacentrus coelestis significantly outperforms other species in terms of both feeding amount and feeding rate on brachiolaria, making it the most optimal predator identified in this study with a consumption rate of 403 larvae/day. There is a significant positive correlation between the density of the P. coelestis and eDNA concentration, with eDNA concentration stabilizing after 96 h of cultivation. The linear function (eDNA concentration = 267,120,000 density - 234,320,000) shows a good fit (R~2 = 0.985), making it generally effective for assessing the resource levels of P. coelestis in stable water environments.
查看更多>>摘要：While the nutrient content of forage species is crucial to study how marine top predators release nutrients in their waste (faeces and urine) and possibly facilitate nutrient recycling at lower trophic levels of the food webs, it is poorly documented in many ecosystems. Here, we analyse the concentrations of five major nutrients, eight essential trace nutrients, and four non-essential nutrients in 34 mesopelagic and demersal forage fish species from the Kerguelen Plateau area (Southern Indian Ocean). This biogeochemically singular region benefits from natural iron (Fe) fertilisation and is an oasis for marine life in the high nutrient low chlorophyll Southern Ocean. Its nutrient dynamics have been subject to intense research for decades, but the contribution of the biota remain unexplored. Local forage fish were found to be significantly heterogeneous in their absolute nutrient concentrations, and in their relative nutrient content. Using hierarchical clustering, we showed that some species were enriched in nutrients found in limited concentrations in Southern Ocean surface waters, such as Fe and manganese (Mn), whereas others were enriched in nutrients likely limiting primary productivity in terrestrial ecosystems, such as phosphorus (P) or calcium (Ca). These fish species could be major contributors to these nutrients' biological cycling in different ecosystems when consumed by predators. This functional typology further demonstrates that prey are not interchangeable. The consumption of one or another prey species modulates not only the ability of the predator to meet its requirements and exposure to contaminants, but also predator-mediated nutrient recycling. This work provides valuable baseline knowledge that can be used in studies of nutrition, nutrient dynamics, and contaminant transfer. It also paves the way for the inclusion of predator-prey relationships in local biogeochemical studies to help unravel the complex processes at work in this unique ecosystem.
查看更多>>摘要：Periphyton are important component indicators in ecosystems, the traditional method of sampling periphyton is not only time-consuming and laborious, but difficult to quantify accurately, which easily causes sample loss and distorts data. On the other hand, the traditional method also requires high proficiency of researchers for sampling. At the same time, when a large number of samples of periphyton need to be collected, the traditional method is inefficient in sampling, so a unified and highly efficient sampling tool is desperately required. Here we present a simple structure, easy operation and low-cost sampling device, Automatic Periphyton Sampler (APS), that can be used to collect periphyton fastly and precisely in a fixed areas of different types of natural substrates. Periphyton from three different natural substrates were collected at different sites using both APS and traditional method, based on the comparison of chlorophyll a content, ash-free dry mass, cell counts, and taxonomic composition. The results show that the APS is more suitable for the periphyton sampling. The study demonstrates that the APS is a portable, efficient, and automated tool that significantly enhances the efficiency of periphyton sampling in the field, and saving labor and time. The new technique can reduce the reliance on researchers and overcome the issue of collecting samples of periphyton on unpickable and stable substrates. Furthermore, modifications can be made to adapt the APS to various natural substrates and field environments.
Julia JacobyAmedee RoySophie LancoChristophe Barbraud...
152099.1-152099.11页
查看更多>>摘要：Tropical oceans are typically oligotrophic but can feature productive environments, such as islands, which can promote high prey availability, influencing predators' foraging strategies in time and space. This study investigates interannual and sex-specific variations in the foraging ecology of the masked booby (Sula dactylatra) in the Fernando de Noronha Archipelago, western tropical Atlantic Ocean. During the 2017, 2018, 2019, and 2022 breeding seasons, blood from birds and muscle samples from regurgitated prey were analyzed for stable isotopes of carbon (δ~(13)C) and nitrogen (δ~(15)N). Simultaneously, birds were tracked with GPS devices and their dives were recorded by pressure sensors and later predicted by deep learning tools to estimate foraging areas. Tracking data revealed foraging areas eastward of the archipelago in all years, potentially driven by the Island Mass Effect. The δ~(13)C and δ~(15)N values varied significantly across the four years, but isotopic niches overlapped, except in 2022. Mixing models estimated the fourwing flying fish Hirundichthys affinis as an important prey source from 2017 to 2019, shifting to false herring Harengula clupeola in 2022. Simultaneously, foraging areas were closer to the archipelago in 2022, with shorter foraging trip duration and length. Stable isotope differences between sexes were occasional, with overlapping niches and foraging areas consistent across years. These findings showcase potential predictability in foraging areas, and also their interannual variability, suggesting shifts in prey availability and distribution around the archipelago. Our results highlight the ecological plasticity of masked boobies in tropical environments and their potential as monitors of fish community dynamics.
Liliana P. ColmanCecilia BaptistotteBrendan J. GodleyJoao C.A. Thome...
152100.1-152100.10页
查看更多>>摘要：Knowledge of sex ratios of species with temperature-dependent sex determination (TSD) is key to provide baseline information which can be used to inform management strategies and predictions of how climate change can affect populations. In marine turtles, increased incubation temperatures can lead to extreme biases in sex ratios and reduced hatching success. Here we present a long-term analysis (34 years) of incubation durations of leatherback turtles (Dermochelys coriacea) in Brazil, the only population of this species breeding in the Southwest Atlantic, and estimate offspring sex ratios. We deployed data loggers recording nest temperatures in 2015, 2016, 2017 and 2019 (n = 28 clutches), to predict offspring sex ratios based on incubation temperatures during the thermosensitive period when sex is determined. The overall mean incubation duration for leatherback turtle clutches in Brazil (1988-2021) was 66.3 days (range 52-91, SD = 6.4, n = 867), decreasing by 4.4 days between the first and last 10 years of monitoring and varying latitudinally across the nesting range of the population. When modelled to the overall nesting season and accounting for nesting seasonality, we estimated the current (2012- 2021) mean season-wide primary sex ratio to be 46.9 % female (range 32.7 % to 84.8 %). Hindcasting for the first ten years of monitoring (1988-1997) showed the average predicted offspring sex ratios would have been 34.6 % female (range 7.7 % to 68.1 %). This population has not shown a phenological shift in the timing of nesting over the period 1988-2021. These findings suggest that, although the primary sex ratio of this population has likely become more female-biased in recent decades, the spatial and temporal variation observed demonstrates some resilience to the effects of increasing temperatures under climate change.
NETL
NSTL
Elsevier