...2007, it wouldn't have seemed profitable to stage an oceanographic biology expedition in midwinter. Without sunlight to power the growth of photosynthetic plankton, there would be nothing to eat ...for the larger zooplankton, which are the primary source offood for seabirds and fish. A sonar instrument revealed that biomass in the fjord's waters dropped to lower depths during the day and ascended towards the surface at night - a signal that marine biologists call diel vertical migration (DVM)2. During our expedition this year, Geoffroy and his colleagues focus on both technology and biology by lowering nets and circular steel frames called rosettes, brimming with optical and acoustic instruments, into the sea.
A total of 16 polycyclic aromatic hydrocarbons (PAHs) were measured in 28 soil column samples from two contaminated industrial sites in Eastern China. The total concentration of 16 PAHs (∑PAHs) in ...the surface soil (0–20 cm) was measured up to 52,600 ng/g (dry weight basis) with a remarkable spatial difference in the studied contaminated sites. The concentrations of the ∑PAHs in soils decreased with the increase in soil depth (0–10 m). The surface and subsurface soil presented a tenfold higher concentration than the soil with depth greater than 4 m. Additionally, the vertical migration tendency of the PAHs was found to be correlated significantly with their hydrophobicity (
R
2
= 0.79,
P
< 0.01). Naphthalene (with lowest octanol–water partition coefficient among the studied PAHs) showed the greatest average soil depth at which its peak concentration occurred. Furthermore, risk quotient analysis by using benzoapyrene as reference compound showed that 71.4% of the samples exhibited high ecological risk for soil. Moreover, the total carcinogenic risk of the PAHs in the surface soil samples was assessed at 5.61 × 10
–5
–1.28 × 10
–4
and 4.41 × 10
–6
–9.43 × 10
–5
for male and female workers, respectively, in which 67.9%–71.4% of the samples showed potential risk. Generally, these results suggest a further consideration of ecological and health risks associated with PAHs in contaminated sites in Eastern China.
Graphical abstract
Abstract In this article we explore universes of circulations, flows and mobilities along two interconnected axes. We propose a reflection on the dynamics of managing bodies and populations in ...transit through categories that regulate journeys and stays, and produce (mal)adaptations. In complementary form, we also question the classificatory processes that pervade the experiences of migrants when they enter distinct regimes of producing difference and are racialized, ethnicized and generified. Our hypothesis is that the connection between these two axes involves the production, at diverse levels, of ‘out of place’ bodies.
Resumo O objetivo do artigo é abordar universos de circulações, fluxos e mobilidades a partir de dois eixos interligados. Por um lado, propomos uma reflexão sobre as dinâmicas de gerenciamento dos corpos e populações em trânsito por meio de categorias que regulam passagens e estadias e produzem (in)adequações. Complementarmente, questionamos os processos classificatórios que perpassam as experiências dos migrantes quando adentram distintos regimes de produção da diferença e são racializados, etnicizados e generificados. Nossa hipótese é a de que a conexão entre os dois eixos abordados se dá pela produção, em diversos níveis, de corpos “fora de lugar”.
Diel vertical migration (DVM) is the most common behavioral phenomenon in zooplankton, and numerous studies have evaluated DVM under strong seasonality at higher latitudes. Yet, our understanding of ...the environmental drivers of DVM at low latitudes, where seasonal variation is less pronounced, remains limited. Therefore, we here examined patterns of vertical distribution in copepods in six subtropical Bahamian blue holes with different food web structure and tested the role of several key environmental variables potentially affecting this behavior. Day and night samplings showed that copepods generally performed DVM, characterized by downward migration to deeper depths during the day and upward migration to surface waters at night. Across all blue holes, the daytime vertical depth distribution of calanoid copepods correlated positively with both predation risk and depth of food resources (Chlorophyll
a
), but was less affected by ultraviolet radiation (UVR). A potential explanation is that since UVR is a continuous threat across seasons, zooplankton have established photoprotective pigmentation making them less vulnerable to this threat. The copepods also showed a size-structured depth segregation, where larger individuals were found at deeper depths during the day, which further strengthens the suggestion that predation is a major driver of DVM in these systems. Hence, in contrast to studies performed at higher latitudes, we show that despite the constant exposure to UVR, predator avoidance and food availability are the most pronounced drivers of copepod DVM at those low latitudes, suggesting that the main driver of DVM may vary among systems, but also systematically by latitude.
To understand hydrocarbon migration in terms of the mechanisms, accumulations and exploration targets, it is essential to correctly identify and characterize the carrier systems that control ...fluid-migration history and oil/gas reservoir formation. The Yinggehai Basin in China is an important area for natural gas exploration and production. However, due to the argillaceous sand sedimentary environment and the absence of faults from the Neogene thermal subsidence period, traditional migration pathways are absent in the Yinggehai Basin, posing significant challenges to target evaluation in this area. Exploration shows that most of the existing gas reservoirs are associated with vertical migration. In this work, coherence cube and curvature seismic techniques are used in the central diapir zone of the Yinggehai Basin to identify diapir-associated fractures and regional stress. Together with geological analysis, two categories of carrier system are discussed in detail to explain the complex migration and accumulation patterns that have puzzled the area. Diapirs have five evolutionary phases, i.e., pressurization, piercing, equilibrium, release and collapse, which have different fracture development patterns, leading to different mechanisms of hydrocarbon migration and accumulation. The carbon isotopes of gaseous hydrocarbons in DF shallow layers and mid-deep layers have an inverted order distribution, indicating mixed accumulation with different maturity, whereas in the mid-deep layers of the diapir-affected areas, there is a single accumulation with low maturity. Early diapiric activity allowed the natural gas produced from deep source rocks to migrate upward along the diapiric carrier system and accumulate in suitable traps to form gas reservoirs. For regional-stress related fractures, the gradual loss of overpressure and fluids from deep to shallow in high-pressure fractures results in the gas accumulation time of deep traps in the regional stress-related carrier system being relatively late and the gas accumulation time of shallow traps being relatively early.
Marine collagen is an ideal material for tissue engineering due to its excellent biological properties. However, the limited mechanical properties and poor stability of marine collagen limit its ...application in tissue engineering. Here, collagen was extracted from the skin of tilapia (Oreochromis nilotica). Collagen-thermoplastic polyurethane (Col-TPU) fibrous membranes were prepared using tilapia collagen as a foundational material, and their physicochemical and biocompatibility were investigated. Fourier transform infrared spectroscopy results showed that thermoplastic polyurethane was successfully combined with collagen, and the triple helix structure of collagen was retained. X-ray diffraction and differential scanning calorimetry results showed relatively good compatibility between collagen and TPU.SEM results showed that the average diameter of the composite nanofiber membrane decreased with increasing thermoplastic polyurethane proportion. The mechanical evaluation and thermogravimetric analysis showed that the thermal stability and tensile properties of Col-TPU fibrous membranes were significantly improved with increasing TPU. Cytotoxicity experiments confirmed that fibrous membranes with different ratios of thermoplastic polyurethane content showed no significant toxicity to fibroblasts; Col-TPU fibrous membranes were conducive to the migration and adhesion of cells. Thus, these Col-TPU composite nanofiber membranes might be used as a potential biomaterial in tissue regeneration.
In the last decades, the migration phenomenon has become one of the greatest humanitarian crises. The generalized solution by the international community has been the reception in refugee camps as a ...temporary solution to the displacement. Nonetheless, conflicts are frequently prolonged in time and migrants are stagnated in protracted situations. The objective of this project is to explore alternatives to refugee camps, namely, the reception of migrants in cities. The project is centered around the idea that this strategy will not only be beneficial for the migrants, who will be able to break the dependency built in the camps, but also for the development of the economies of the host countries, by creating more employment, generating a more competitive market, and promoting the development of the infrastructures of the cities. This is going to be studied from the perspective of Ecuador, the country of Latin America that hosts more refugees and migrants, without the establishment of camps.
Survival of post‐larval and juvenile organisms can depend on multiple seasonally‐fluctuating features, including thermal conditions and food availability. Alterations in the phenology of either ...consumers or their prey might decouple trophic relationships and reduce consumer growth and survival, and this potential for mismatches is especially pronounced in migratory organisms that change habitats. Juvenile sockeye salmon (Oncorhynchus nerka) migrate from natal streams to lake habitats, and we hypothesised that their in‐lake growth and survival depends on whether timing of migration matches suitable lake conditions.
We used mixed effects models to test the hypotheses that: (a) the most successful entry times correspond to favourable prey densities and lake thermal conditions; and (b) a mismatch in fish entry time and seasonal lake dynamics can reduce fish growth and survival. These models were applied to an 11‐year time series of migration timing, capture rate and size at smolting for juvenile sockeye salmon in Lake Washington, WA, USA.
Juvenile sockeye salmon entering Lake Washington later in the season encountered higher zooplankton abundance and warmer water, and experienced higher average rates of growth and survival, but the optimal date for lake entry ranged across years by up to a month. Zooplankton abundance and bloom timing affected fish growth and relative survival more than lake temperature, and survival was most influenced by zooplankton abundance in the spring when fish entered the lake. In contrast, fish size at seaward migration from the lake depended primarily on zooplankton abundance in the spring as they left the lake rather than the previous spring when they entered.
These results suggest that maintaining a wide window of lake entry dates allows this population to capture the annually‐varying period of favourable conditions, minimising mismatches between juvenile fish and their resources and thereby enabling successful recruitment in an unpredictable environment.
Environmental DNA (eDNA) metabarcoding is emerging as a novel, objective tool for monitoring marine metazoan biodiversity. Zooplankton biodiversity in the vast open ocean is currently monitored ...through continuous plankton recorder (CPR) surveys, using ship‐based bulk plankton sampling and morphological identification. We assessed whether eDNA metabarcoding (2 L filtered seawater) could capture similar Southern Ocean zooplankton biodiversity as conventional CPR bulk sampling (~1,500 L filtered seawater per CPR sample). We directly compared eDNA metabarcoding with (a) conventional morphological CPR sampling and (b) bulk DNA metabarcoding of CPR collected plankton (two transects for each comparison, 40 and 44 paired samples, respectively). A metazoan‐targeted cytochrome c oxidase I (COI) marker was used to characterize species‐level diversity. In the 2 L seawater eDNA samples, this marker amplified large amounts of non‐metazoan picoplanktonic algae, but eDNA metabarcoding still detected up to 1.6 times more zooplankton species than morphologically analysed bulk CPR samples. COI metabarcoding of bulk DNA samples mostly avoided nonmetazoan amplifications and recovered more zooplankton species than eDNA metabarcoding. However, eDNA metabarcoding detected roughly two thirds of metazoan species and identified similar taxa contributing to community differentiation across the subtropical front separating transects. We observed a diurnal pattern in eDNA data for copepods which perform diel vertical migrations, indicating a surprisingly short temporal eDNA signal. Compared to COI, a eukaryote‐targeted 18S ribosomal RNA marker detected a higher proportion, but lower diversity, of metazoans in eDNA. With refinement and standardization of methodology, eDNA metabarcoding could become an efficient tool for monitoring open ocean biodiversity.
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