Affiner votre recherche
Résultats 1811-1820 de 4,937
Land use-induced change in trophic state of Shenzhen Bay (South China) over the past half-century Texte intégral
2019
Yan, Hongyu | He, Xiufang | Lei, Yuanda | Wang, Yasu | Su, Hong | Jiang, Shijun
Mangroves connect terrestrial and marine ecosystems and are sensitive to environmental change, and the sediments within faithfully record long-term changes in the aquatic environment and supplement the generally short monitoring archives. Here we present a sediment-core record of TN, TP, TOC, and C/N ratios from the Futian mangrove wetland, Shenzhen Bay (South China), and compare with our remote sensing-derived land use change and the nearby seawater monitoring records. Our reconstructed record extends the history of tropic state change back to the Year 1958, supplementing the monitoring activity initiated in 1987. More importantly, the results reveal two distinct periods. The pre-1983 period (Year 1958–1982) is characterized by increased nutrient due to agricultural activities, while the post-1983 period (Year 1983–2014) is marked by reduced TP but relatively stable TN values, during which the simultaneous increase in construction lands and C/N ratios suggests enhanced soil erosion due to the rapid urbanization of Shenzhen City.
Afficher plus [+] Moins [-]Zooplankton dynamics in a highly eutrophic microtidal estuary Texte intégral
2019
Rose, Thomas H. | Tweedley, James R. | Warwick, Richard M. | Potter, I. C.
Mesozooplankton was sampled seasonally in a large microtidal estuary (Peel-Harvey) suffering from massive macroalgal growths and cyanobacterial blooms. Comparisons with other estuaries indicate that eutrophication led to copepod abundance declining and macroalgal-associated species increasing. Mesozooplankton species are almost exclusively autochthonous, i.e. spend entire life cycle within the estuary. Meroplanktonic species are virtually absent because main benthic macroinvertebrate species undergo direct benthic rather than planktotrophic development. There are also few abundant holoplanktonic species. Most species are tychoplanktonic, i.e. benthic and transported into plankton through physical disturbance of sediment. Species number, concentration and Simpson's Index are greater during night than day. Annual cyclical changes in species composition are related closely to changes in salinity. At the most degraded site, nematode concentrations were high and the species number and concentration changed markedly during extreme eutrophication, when oxygen concentrations were low, disrupting annual cyclical changes in species composition.
Afficher plus [+] Moins [-]Hydrocarbon molecular markers in the Holocene bottom sediments of the Barents Sea as indicators of natural and anthropogenic impacts Texte intégral
2019
Morgunova, Inna P. | Petrova, Vera I. | Litvinenko, Ivan V. | Kursheva, Anna V. | Batova, Galina I. | Renaud, Paul E. | Granovitch, Andrei I.
The recent intensification of energy resource exploration and human activities in the Barents Sea (BS) requires a more thorough assessment of the natural and anthropogenic impact of hydrocarbons on the environment. We analyzed a wide set of sensitive indicators, including hydrocarbon molecular markers and organic matter (OM) maturity parameters in the Holocene sediments from three regions of the BS: the Kola-Kanin Monocline (KKM), the Svalbard shelf, and the Shtokman gas-condensate field (GCF). An increase in pyrogenic polycyclic aromatic hydrocarbons toward the core surface traces the intensification of anthropogenic contamination in the KKM region during last century. An input of highly mature OM from the eroded coal rocks of Barentsburg were confirmed by comparison of biomarker distribution in sediments and coals. An increase in biogenic hopanes and hopenes content down-core, and a crude-oil stage of OM maturity in surface sediments of the Shtokman GCF attests to hydrocarbons migration from subsurface strata.
Afficher plus [+] Moins [-]Detecting the occurrence of indigenous and non-indigenous megafauna through fishermen knowledge: A complementary tool to coastal and port surveys Texte intégral
2019
Azzurro, E. | Bolognini, L. | Dragičević, B. | Drakulović, D. | Dulčić, J. | Fanelli, E. | Grati, F. | Kolitari, J. | Lipej, L. | Magaletti, E. | Marković, O. | Matić-Skoko, S. | Mavrič, B. | Milone, N. | Joksimović, A. | Tomanić, J. | Scarpato, A. | Tutman, P. | Vrdoljak, D. | Zappacosta, F.
Marine bioinvasions and other rapid biodiversity changes require today integrating existing monitoring tools with other complementary detection strategies to provide a more efficient management. Here we explored the efficacy of fishermen observations and traditional port surveys to effectively track the occurrence of both indigenous and non-indigenous megafauna in the Adriatic Sea. This consisted mainly of mobile taxa such as fishes, crustaceans and molluscs. Port surveys using traps and nets within 10 major Adriatic harbours, were compared with the information obtained from 153 interviews with local fishermen. Information gathered by traps and nets varied significantly and generally resulted of limited efficacy in exotic species detection. Interviews allowed tracking the occurrence of new species through time and space, providing complementary knowledge at the low cost. This combined approach improves our capability of being informed on the arrival of species of different origin, providing a more rational, improved basis for environmental management and decision making.
Afficher plus [+] Moins [-]Historical records of trace metals in core sediments from Jiangsu coastal area, China Texte intégral
2019
Qiu, Jiandong | Yin, Ping | Liu, Jinqing | Cao, Ke | Li, Meina | Wang, Shuang
The major and trace metal (Cu, Pb, Zn, Cr, Cd, As, Hg, Ni, Li, and Co) concentration profiles along a 60.2-m-long sediment core are investigated to assess their depositional trends and contamination levels in the Jiangsu coastal area, China. All of the metals, except Cd, had similar profiles that exhibited increasing concentrations during the Holocene. Their enrichment factors indicate that the metals were naturally sourced throughout the observed depositional period, with the exception of As, Hg, and Li, which may have also had anthropogenic sources. Their geoaccumulation indices indicate that the sediments were not contaminated by any metals prior to the Holocene, whereas they were contaminated by As, Hg, and Li throughout the Holocene (11–0 ka), and by Pb, Cr, and Zn since 2 ka.
Afficher plus [+] Moins [-]Morpho-functional effects of heat stress on the gills of Antarctic T. bernacchii and C. hamatus Texte intégral
2019
Garofalo, Filippo | Santovito, Gianfranco | Amelio, Daniela
The effect of increasing ocean water temperature on morpho-functional traits of Antarctic marine species is under intense attention.In this work, we evaluated the effects of acute heat stress on the gills of the Antarctic haemoglobinless Chionodraco hamatus and the red blooded Trematomus bernacchii in terms of morphology, heat shock response, antioxidant defense and NOS/NO system. We showed in both species that the exposure to high temperature (4 °C) induced structural alterations, such as epithelial lifting and oedema of secondary lamellae. By immunolocalization we also observed that HSP-90, HSP-70, Xantine Oxidase, Heme Oxigenase and NOS are expressed in both species under control conditions. After heat stress the signals increase in C. hamatus being absent/or reduced in T. bernacchii. Our preliminary results suggest a specie-specific morpho-functional response of the gills of the two Antarctic teleosts to heat stress.
Afficher plus [+] Moins [-]A 3D numerical model to Track Marine Plastic Debris (TrackMPD): Sensitivity of microplastic trajectories and fates to particle dynamical properties and physical processes Texte intégral
2019
Jalón-Rojas, Isabel | Wang, Xiao Hua | Fredj, Erick
Numerical modelling is a key tool in understanding and determining the sources, trajectories and fates of micro-plastic debris (MPD). In this study, we introduce TrackMPD, a new modelling framework for the 3D transport of marine debris. TrackMPD fills the gaps in previous models by: (1) using a three-dimensional approach; (2) providing compatibility with a variety of ocean models; and (3) including a wide range of physical processes (advection, dispersion, windage, sinking, settling, beaching and re-floating) and MPD behaviours that depend on particle dynamical properties, and the fouling and degradation states. We implement a sensitivity analysis based on 44 scenarios to assess the relative importance of the different processes and behaviours on the MPD trajectories and fates. Results show that the MPD dynamical properties that impact their sinking, in particular plastic density and biofilm thickness and density, have the biggest effect on the MPD transport, followed by turbulent dispersion and washing-off.
Afficher plus [+] Moins [-]Strategy of port baseline surveys (PBS) in the Adriatic Sea Texte intégral
2019
Kraus, Romina | Ninčević-Gladan, Živana | Auriemma, Rocco | Bastianini, Mauro | Bolognini, Luca | Cabrini, Marina | Cara, Magdalena | Čalić, Marijeta | Campanelli, Alessandra | Cvitković, Ivan | Despalatović, Marija | Dragičević, Branko | Drakulović, Dragana | Dulčić, Jakov | Flander-Putrle, Vesna | Grati, Fabio | Grego, Mateja | Grilli, Federica | Jaklin, Andrej | Janeković, Ivica | Kolitari, Jerina | Lipej, Lovrenc | Magaletti, Erika | Marini, Mauro | Matić-Skoko, Sanja | Mavrič, Borut | Mikuš, Josip | Mozetič, Patricija | Orlando Bonaca, Martina | Petović, Slavica | Precali, Robert | Supić, Nastjenjka | Trabucco, Benedetta | Travizi, Ana | Žuljević, Ante
Port baseline surveys (PBS) provide species inventories in and around ports, with a focus on non-indigenous species that may have been introduced by vessels, primarily via ballast water. PBS are an essential tool to support effective management strategies for non-indigenous as well as native harmful aquatic organisms and pathogens (HAOP). This paper describes the methodology of PBS that were conducted in 12 Adriatic ports. The PBS employed existing protocols that were adapted to meet the characteristics of the Adriatic sites. Their results are reported in several papers included in this special issue, each of which is devoted to a specific community. An overview of existing surveys protocols – which provide valuable support to decision-making and to design effective monitoring of non-indigenous species – is also supplied.
Afficher plus [+] Moins [-]Preliminary study and first evidence of presence of microplastics and colorants in green mussel, Perna viridis (Linnaeus, 1758), from southeast coast of India Texte intégral
2019
S.A., Naidu
Pollution by microplastics (MPs) is currently a global problem in the coastal and marine environment. Transfer of MPs from land to sea and their inclusion in the food web has a significant adverse effect on the marine life and human health. The present study was carried out at the fishing harbour of Chennai, southeast coast of India. The possible MPs were isolated from the soft tissues of the commercially important bivalve Perna viridis and examined by microscopic and DXR Raman spectroscopic methods. The MPs were identified as to be polystyrene polymers in the soft tissues. This investigation revealed that size and color are the major factors affecting the bioavailability of MPs to bivalves in the study area. The presence of colorants in organisms revealed an anthropogenic origin through the use of a wide array of applications. Hence, coastal zones are a hotspot for pollution by MPs, and filter feeding bivalves are at the highest risk. Therefore, further studies are required to understand the accumulation rates and residence time of MPs across the food webs.
Afficher plus [+] Moins [-]Using solitary ascidians to assess microplastic and phthalate plasticizers pollution among marine biota: A case study of the Eastern Mediterranean and Red Sea Texte intégral
2019
Vered, Gal | Kaplan, Aviv | Avisar, Dror | Shenkar, Noa
The interaction of microplastic (MP) with marine organisms is crucial for understanding the significant effect that MP and its additives may have on marine environments. However, knowledge regarding the magnitude of these pollutants in the Eastern Mediterranean Sea and the tropical Red Sea is still scarce. Here we examined the levels of phthalate acid esters (PAEs) and MP in Herdmania momus and Microcosmus exasperatus sampled along the Mediterranean and Red Sea coasts of Israel. High levels of dibutyl phthalate (DBP) and bis (2‑ethylhexyl) phthalate (DEHP) were found in ascidians at the majority of sampling sites, and MP particles were found in ascidians at all sites. As efficient filter-feeders and being widely-distributed, invasive ascidians present fundamental opportunities for the environmental monitoring of microplastic and its additives worldwide. The high levels of pollutants revealed emphasize the need for further research into the magnitude and effects of MP and PAEs in these regions.
Afficher plus [+] Moins [-]