Recruitment of flatfish species to an estuarine nursery habitat (Lima estuary, NW Iberian Peninsula)

One of the present concerns of fish biologists involves defining and identifying nursery habitats in the context of conservation and resource management strategies. Fish nursery studies usually report upon nursery occupation during the latter juvenile stages, despite the fact that recruitment to nurseries can start early in life, during the larval phase. Here we investigated the use of a temperate estuarine nursery area, the Lima estuary (NW Portugal), by initial development stages of flatfish species before and after metamorphosis, integrating the larval and juvenile phases. The Lima estuarine flatfish community comprised twelve taxa, seven of which were present as pelagic larvae, six as juveniles and three as adults. There was a general trend of increasing spring–summer abundance of both larvae and juveniles, followed by a sharp winter decrease, mainly of larval flatfishes. The Lima estuary was used by Solea senegalensis, Platichthys flesus and Solea solea as a nursery area, with direct settlement for the two first species. In contrast, indirect settlement was suggested for S. solea, with metamorphosis occurring outside the estuarine area. Estuarine recruitment of S. senegalensis varied between years, with young larvae occurring in the estuary throughout a prolonged period that lasted 6–9 months, corroborating the protracted spawning season. P. flesus, the second most abundant species, exhibited a typical spring estuarine recruitment, without inter-annual variations. Developed larvae arrived in the estuary during spring, whereas the 0-group juveniles emerged in the following summer period. The present study contributes new insight to our understanding of the economically important S. senegalensis, and highlights the importance of integrating the planktonic larval phase into traditional flatfish nursery studies.     

The measurement of the decorrelation function in underground muon pairs as a probe of primary cosmic ray interactions

We discuss the measurement of the average angle within pairs of muons detected in underground experiments versus their relative distance, as a tool for studying primary Cosmic Ray interactions. We propose to call Φ(d) “decorrelation” function. Under simplifying approximation, the decorrelation function can be computed analytically to show its dependence on details of cosmic ray interactions as well as on the propagation in the rock. We argue that this new measurement is useful in a real experiment, complementing traditional ones like the decoherence function.     

Effects of furadan in the brown mussel Perna perna and in the mangrove oyster Crassostrea rhizophorae

Furadan is a carbamate pesticide used widely to combat agricultural pests. However little information is available about the toxicity of furadan in aquatic macroinvertebrates. The in vivo effects of furadan were evaluated in mussels, Perna perna, and oysters, Crassostrea rhizophorae. Glutathione S-transferase (GST), catalase (CAT) and cholinesterase (ChE) activities were measured in the gills of both species exposed to furadan (100 microg/l) for 96 h. No changes were observed in GST activity in the exposed groups. CAT activity was higher (9%) in the oysters exposed to furadan. ChE activity was inhibited by 64 and 35%, respectively, in C. rhizophorae and P. perna exposed to furadan, suggesting that the former is more susceptible to the toxic effects of furadan.     

Development of agroclimatic zoning model to delimit the potential growing areas for macaw palm (Acrocomia aculeata)

Theoretical and Applied Climatology - The growing biodiesel production requires the use of new technologies and alternative feedstocks to maintain the growing demand of this biofuel. The macaw...     

Paleolimnological records reveal biotic homogenization driven by eutrophication in tropical reservoirs

Biodiversity changes in response to eutrophication, climate variability and species invasions. These pressures have been shown to reduce community heterogeneity at various scales; however, how productivity drives homogenization patterns in a community of primary producers, such as diatoms, has not been studied. Using a dataset with good temporal resolution, obtained from cores collected from seven tropical reservoirs, we evaluated patterns of spatial and temporal homogenization, i.e. the trends in temporal α-diversity and spatial β-diversity (change in community composition), of diatom assemblages over the past 60–100 years. The paleolimnological records allowed us to study biodiversity trends since the initial community (reservoir construction) in those systems with low anthropogenic impact and also those undergoing eutrophication. No clear trend of spatial β-diversity change over time was found when all reservoirs were analyzed together. However, when only eutrophic reservoirs were considered, a marked decrease in the spatial β-diversity occurred, suggesting that eutrophication leads to homogenization of the diatom assemblage. These findings were reinforced by the lack of change in β-diversity when the age of the reservoirs was standardized, indicating that the reservoirs’ ontogeny did not influence the spatial β-diversity trend and β-diversity did not increase even in the reservoirs with low anthropogenic impact. In addition, the results showed a decrease of α-diversity over time for almost all the eutrophic reservoirs, as well as a decrease in the total species pool for the reservoirs, although periphytic diatoms may be favored by the appearance and sometimes mass development of floating macrophytes in warm, shallow eutrophic reservoirs. This study supports the role of eutrophication as one of the main drivers of diatom assemblage homogenization in tropical reservoirs, with a significant loss of species over time.     

A hypoplastic macroelement for single vertical piles in sand subject to three-dimensional loading conditions

This paper presents a novel macroelement for single vertical piles in sand developed within the hypo-plasticity theory, where the incremental nonlinear constitutive equations are defined in terms of generalized forces, displacements and rotations. Inspired from the macroelement for shallow foundations of Salciarini and Tamagnini (Acta Geotech, 4(3):163–176, 2009), the new element adopts the “intergranular displacement” mutuated from Niemunis and Herle (Mech Cohes Frict Mater, 2:279–299, 1997) to reproduce the behavior under cyclic loading. Analytical and numerical strategies are provided to calibrate the macroelement’s parameters. Comparisons with experimental results show the performance of the macroelement that while being simple and computational fast is suitable for finite element calculations and engineering design.     

Vegetation changes in the Neotropical Gran Sabana (Venezuela) around the Younger Dryas chron

The occurrence of the Younger Dryas cold reversal in northern South America midlands and lowlands remains controversial. We present a palaeoecological analysis of a Late Glacial lacustrine section from a midland lake (Lake Chonita, 4.6501 °N, 61.0157 °W, 884 m elevation) located in the Venezuelan Gran Sabana, based on physical and biological proxies. The sediments were mostly barren from ～15.3 to 12.7 k cal a BP, probably due to poor preservation. A ligneous community with no clear modern analogues was dominant from 12.7 to 11.7 k cal a BP (Younger Dryas chronozone). At present, similar shrublands are situated around 200 m elevation above the lake, suggesting a cooling‐driven downward shift in vegetation during that period. The interval from 11.7 to 10.6 k cal a BP is marked by a dramatic replacement of the shrubland by savannas and a conspicuous increase in fire incidence. The intensification of local and regional fires at this interval could have played a role in the vegetation shift. A change to wetter, and probably warmer, conditions is deduced after 11.7 k cal a BP, coinciding with the early Holocene warming. These results support the hypothesis of a mixed origin (climate and fire) of the Gran Sabana savannas, and highlight the climatic instability of the Neotropics during the Late Glacial. Copyright © 2011 John Wiley & Sons, Ltd.     

Geochronology, petrology and geochemistry of the Nanlinshan and Banpo mafic–ultramafic intrusions: implications for subduction initiation in the eastern Paleo-Tethys

The Nanlinshan and Banpo mafic–ultramafic intrusions belong to the prominent Yunxian-Jinghong magmatic belt in the western part of the Simao Block, one of several Gondwana-derived continental fragments assembled by the closure of multiple Tethyan oceans. Different petrogenic models including ophiolites, MORB-type cumulates and Alaskan-type complexes have been proposed for these intrusions. In order to better constrain possible origins, we have undertaken an integrated geochronological, petrological and geochemical study of both intrusions. Precise CA-ID-TIMS zircon U–Pb dating indicates that the Nanlinshan and Banpo intrusions have similar ages of ~298 and 295?Ma, respectively, confirming that they are the oldest intrusive rocks in the Yunxian-Jinghong magmatic belt. A comparison between whole rock compositions and the compositions of major silicate minerals, including trace elements in clinopyroxene, reveals that (1) the ultramafic rocks of these intrusions are crystal cumulates of a relatively primitive magma, (2) the associated gabbroic and dioritic rocks are the products of more fractionated liquids, and (3) the parental magmas of these rocks were all depleted in some high field strength trace elements including Nb, Zr and Hf. Both intrusions are also characterized by elevated ε_Nd values between +3.4 and +6.6. The positive ε_Nd values coupled with negative Nb and Zr–Hf anomalies are consistent with the interpretation that these two intrusions are the products of subduction-related basaltic magmatism. The results from this study suggest that subduction of the Paleo-Tethys Ocean along the western margin of the Simao Block initiated as early as ~298?Ma and that the Simao Block and the Northern Qiangtang Block of the Tibet Plateau are separate Gondwana-derived continental fragments instead of a single fragment as previously reported.     

The COVID-19 pandemic and global environmental change: Emerging research needs

The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.