Ecological niches and areas of overlap of the squat lobster ‘munida’ (Pleuroncodes monodon) and anchoveta (Engraulis ringens) off Peru   总被引：1，自引：1，他引：0  

Mariano Gutirrez  Argiro Ramirez  Sophie Bertrand  Octavio Mron  Arnaud Bertrand 《Progress in Oceanography》2008,79(2-4):256

The world’s largest mono-specific fishery, the Peruvian anchovy or anchoveta (Engraulis ringens) fishery, has been the subject of many studies since the 1960s. Details of its relationship with other species have mainly focused on alternations with sardine, Sardinops sagax, and little effort has so far been paid to interactions with other species sharing the same ecosystem. This is the case for Pleuroncodes monodon, the crustacean squat lobster or ’munida’, which has become highly abundant along the Peruvian coast since the mid-1990s. Munida is now an important prey for seabirds, mammals and coastal predatory fish. Knowledge of patterns of distribution and ecological niche of munida is scarce however off Peru. Here we describe and compare spatial patterns of distribution of anchoveta and munida and their ecological niches based on data from 26 acoustic surveys performed along the Peruvian coast between 1998 and 2006. The results indicate that munida and anchoveta share ecological niches but that munida is restricted to the coldest part of the productive cold coastal waters whereas anchoveta do not present any temperature preference over a large range (14–23 °C). The recent increase in munida abundance off Peru is concomitant with colder conditions; with their onset munida extended its range from central Chile northwards. Off Peru the very shallow oxycline keeps munida from its usual bottom habitat and has forced it to adopt pelagic behaviour.  相似文献   

Effects of morphodynamic state on macrofauna community of exposed sandy beaches on Galician coast (NW Spain)     

Rosario de la Huz  & Mariano Lastra 《Marine Ecology》2008,29(S1):150-159

It is known that the fauna of the exposed sandy beaches are primarily controlled by physical variables; but how these variables operate along and across the beach still remains fairly under discussion. In our study, we sampled a range of exposed sandy beaches along the Northwest coast of Spain to determine the relationship between the principal physical variables of the beaches (including beach morphodynamic state), and the macrofaunal community. The fauna of these beaches comprise truly marine species along the intertidal zone as well as semi-terrestrial species in the upper and supratidal environments. These two groups respond in a different manner to the physical environment. The first group is directly controlled by the morphodynamic state of the beach, and variations in the physical environment; the second group is not clearly affected by these physical conditions. In this case, other variables such as food availability and the human uses of the upper limits of the beach seem to be more relevant in explaining the patterns observed in the macrofaunal community.  相似文献   

Sandy beach ecosystems: key features, sampling issues, management challenges and climate change impacts   总被引：4，自引：0，他引：4  

Thomas A. Schlacher  Dave S. Schoeman  Jenifer Dugan  Mariano Lastra  Alan Jones  Felicita Scapini  & Anton McLachlan 《Marine Ecology》2008,29(S1):70-90

Escalating pressures caused by the combined effects of population growth, demographic shifts, economic development and global climate change pose unprecedented threats to sandy beach ecosystems worldwide. Conservation of beaches as functional ecosystems and protection of their unique biodiversity requires management interventions that not only mitigate threats to physical properties of sandy shores, but also include ecological dimensions. Yet, beach management remains overwhelmingly focused on engineering interventions. Here we summarise the key outcomes of several workshops, held during the 2006 Sandy Beach Ecology Symposium in Vigo, Spain, that addressed issues of climate change, beach management and sampling methodology. Because efficient communication between managers and ecologists is critical, we summarise the salient features of sandy beaches as functional ecosystems in 50 'key statements'; these provide a succinct synopsis of the main structural and functional characteristics of these highly dynamic systems. Key outcomes of the workshops include a set of recommendations on designs and methods for sampling the benthic infaunal communities of beaches, the identification of the main ecological effects caused by direct and indirect human interventions, the predicted consequence of climate change for beach ecosystems, and priority areas for future research.  相似文献   

Long-term water monitoring in two Mediterranean lagoons as an indicator of land-use changes and intense precipitation events (Adra,Southeastern Spain)     

Miguel Rodríguez-Rodríguez  José Benavente  Francisco J. Alcalá  Mariano Paracuellos 《Estuarine, Coastal and Shelf Science》2011,91(3):400-410

During recent historical times the Adra river delta, a detrital coastal aquifer of nearly 32 km² located in a semi-arid, mountainous area of SE Spain, has undergone different changes caused by human activity. Within this context, both the river dynamics in the plain and the geomorphology of the coastline have at various times resulted in the formation of small lagoons. At present only two small (<0.5 km²) lagoons exist, at the eastern edge of the aquifer, which, although closely surrounded by commercial market-garden greenhouses, are protected under international agreements. During the last 30 years of the twentieth century traditional agricultural irrigation techniques have undergone significant changes to improve their efficiency. Surface-water resources in the Adra river basin are regulated via the Beninar reservoir. In addition, the use of groundwater is increasing progressively. Both these factors affect the recharge of the coastal aquifer. To monitor these changes measurements of electrical conductivity and water level fluctuations have been recorded in these lagoons for the last 35 years (1975–2010). A comparison of the hydrochemical characteristics of the water in the lagoons and of the surrounding groundwater from 2003 to 2010 shows marked differences induced by the different hydrological dynamics in each lagoon, as well as by the hydrogeological impact of changes in land use in the delta. The increase in water demand is a consequence of the extension of irrigated areas from the fluvio-deltaic plain to its slopes, originally occupied by unirrigated crops. A reduction in irrigation return-flow is linked to the use of new irrigation techniques. These modifications affect both the recharge regime of the aquifer and its water quality. Moreover, extreme precipitation events, which are characteristic of Mediterranean semi-arid environments, can affect the lagoons’ hydrological dynamics to a considerable extent. One such example is the unusually rainy period from January to March 2010 (>600 mm). This event, along with other effects, has dramatically lowered the salinity of the water in both lagoons. This case study reveals the extreme vulnerability of deltaic environments and also how lagoons can reflect anthropogenic changes over the whole river basin.  相似文献   

500 Years of rainfall variability and extreme hydrological events in southeastern Spain drylands     

M.J. Machado  G. Benito  M. Barriendos  F.S. Rodrigo 《Journal of Arid Environments》2011,75(12):1244-1253

The semiarid SE fringe of the Iberian Peninsula is considered one of the most sensitive to extreme floods and droughts in the western Mediterranean area. The controlling climatic mechanisms are nevertheless difficult to predict and model. A combined documentary-sedimentary-instrumental 500 years comprehensive register of climatic data (rainfall and flooding) was collated for analysing the decadal to centennial scale hydrological response. Wet years are closely linked to the presence of autumn (SON) positive anomalies (e.g. early 18th century). However, continuous, decadal wet periods seem to correspond in time to both autumn and spring (MAM) positive rainfall anomaly years (e.g. 1570/90, 1830/40, 1870/1900). High frequencies of large floods were registered during the late Medieval Warm Period (AD 950–1200), and during some decades of the Little Ice Age with an average of 0.22 floods/year (1440–1490, 1520–1570, 1600–1740, 1770–1800, 1820–1840, 1870–1900), but flood frequency decreased in the 20th Century (1945–1973; 0.14 floods/year). During wet phases (e.g. late 19th century), large floods occurred during all seasons, whereas a predominantly autumn extreme flooding (>70%) is linked to a rainfall patterns with higher inter-annual variability (e.g. 1945–1973). The recurrence of dry phases is higher since early 17th century, and the frequency of continuous wetter phases lower than the ones with marked annual variability. This results in a trend with less frequent high magnitude catastrophic floods. This study confirms a shift from autumn rainfall maxima towards winter since the early 1990's. The tendency towards longer dry periods and increased inter-annual variability (with 1–3 years maximum wet spells) and a changing seasonal rainfall distribution are thought to be key in modelling projections for this specific arid Mediterranean region.  相似文献   

Feedback Mechanisms Between Cyanobacterial Blooms,Transient Hypoxia,and Benthic Phosphorus Regeneration in Shallow Coastal Environments     

Mindaugas Zilius  Marco Bartoli  Mariano Bresciani  Marija Katarzyte  Tomas Ruginis  Jolita Petkuviene  Irma Lubiene  Claudia Giardino  Paul A. Bukaveckas  Rutger de Wit  Arturas Razinkovas-Baziukas 《Estuaries and Coasts》2014,37(3):680-694

We investigated the dissolved oxygen metabolism of the Curonian Lagoon (Baltic Sea) to assess the relative contributions of pelagic and benthic processes to the development of transient hypoxic conditions in shallow water habitats. Metabolism measurements along with the remote sensing-derived estimates of spatial variability in chlorophyll a were used to evaluate the risk of hypoxia at the whole lagoon level. Our data demonstrate that cyanobacterial blooms strongly inhibit light penetration, resulting in net heterotrophic conditions in which pelagic oxygen demand exceeds benthic oxygen demand by an order of magnitude. The combination of bloom conditions and reduced vertical mixing during calm periods resulted in oxygen depletion of bottom waters and greater sediment nutrient release. The peak of reactive P regeneration (nearly 30 μmol m^?2 h^?1) coincided with oxygen depletion in the water column, and resulted in a marked drop of the inorganic N:P ratio (from >40 to <5, as molar). Our results suggest a strong link between cyanobacterial blooms, pelagic respiration, hypoxia, and P regeneration, which acts as a feedback in sustaining algal blooms through internal nutrient cycling. Meteorological data and satellite-derived maps of chlorophyll a were used to show that nearly 70 % of the lagoon surface (approximately 1,000 km²) is prone to transient hypoxia development when blooms coincide with low wind speed conditions.  相似文献   

Magnetic anomalies in the Eastern Caribbean     

Nuris Orihuela Guevara  Andreína García  Mariano Arnaiz 《International Journal of Earth Sciences》2013,102(3):591-604

Despite the many different studies on the origin and evolution of the Caribbean Plate, no proposal has been widely accepted so far. A key element within this field of research is the characterization of the plate subsurface oceanic crust, as it would clarify the conditions in which it originated, the geological period when it formed and its possible geographical location at this first evolution stage. Based on partial results of this research work, we can say that the conclusions of previous studies are valid to a great extent, namely the NE–SW orientation of the striped magnetic anomalies in the Venezuelan Basin’s western section and the existence of W–E preferentially oriented stripes parallel to the Leeward Antilles. The magnetic response of the triangular section in the southeast of the Venezuelan Basin represents cretaceous magnetic quiet zone (CMQZ) and therefore shows a considerable attenuation of the stripe pattern, indicating that the whole East Caribbean subsurface features oceanic crustal material. As for the period recorded by the Caribbean magnetic stripes, we propose the interval between chrons M23 and M0, and part of CMQZ. The wavelengths of the identified anomalies suggest that the ridge associated with the formation of Caribbean ocean floor was slow-spreading when compared to average currently active ridges.  相似文献   

PIANCALDOLI METEORITE: CHEMISTRY,MINERALOGY AND PETROLOGY     

Marcello Carapezza  P. Mario Nuccio  Mariano Valenza 《Meteoritics & planetary science》1976,11(3):195-205

The fall occurred near Piancaldoli, Florence, Italy, at 19.14 U.T. on the 10th August 1968. The fireball broke up in the atmosphere producing a cloud like a balloon. The trajectory and the terminal point were calculated, leading to the recovery of three small meteoritic fragments, found on the roof of a house. Chemical analysis gave the following results: SiO₂ 40.80; TiO₂ 0.15; Al₂O₃ 2. 70; Cr₂O₃ 0.47; FeO 17.20; MnO 0.07; MgO 25.18; CaO 1.95; Na₂O 0.64; K₂O 0.07; P₂O₅ 0.20; NiS 0.93; FeS 6.24; Fe° 2.40; Ni° 0.40; Co 0.05; sum 99.45. In the lithic portion of the meteorite the following minerals were found: both clino and orthopyroxenes (En = 76 to 98%), olivines (Fo = 66 to 98%), troilite, pyrrhotite, pentlandite, kamacite, ilmenite, apatite, merillite, schreibersite, chromite and Henderson phase. From all the mineralogical and petrological data, we conclude that the Piancaldoli meteorite is an “unequilibrated ordinary chondrite,” LL3. The microbrecciated structure of the rock and some shock features were observed, while the rock as a whole is unshocked, suggesting that these features were caused by impact events which took place during the accretion of the parent body.  相似文献   

Uptake of hazardous elements by spring onion (<Emphasis Type="Italic">Allium fistulosum</Emphasis> L.) from soil irrigated with different types of water and possible health risk     

Kafeel Ahmad  Zafar Iqbal Khan  Asma Ashfaq  Muhammad Ashraf  Nudrat Aisha Akram  Muhammad Sher  Hazoor Ahmad Shad  Vincenzo Tufarelli  Antonio Lonigro  Mariano Fracchiolla  Eugenio Cazzato 《Environmental Earth Sciences》2017,76(8):322

Bio-concentration of elements such as Mo, As, Se, Fe, Cu, Zn, Ni and Pb was analyzed in spring onion (Allium fistulosum L.) in three different locations of central Punjab, Pakistan. At location GW, relatively low level of hazardous elements was found in spring onion, suggesting that groundwater is a safe source of water for irrigating food crops. The pH of soil at wastewater irrigation was found less acidic (pH 7.4) than the other sites. The range of concentration in the different samples of spring onion was as follows: 6.15–8.16 mg kg^?1 for Mo, 2.77–4.28 mg kg^?1 for As, 0.395–0.705 mg kg^?1 for Se, 36.73–48.17 mg kg^?1 for Fe, 10.58–16.26 mg kg^?1 for Cu, 28.87–39.79 mg kg^?1 for Zn, 6.66–8.75 mg kg^?1 for Ni and 4.33–6.09 mg kg^?1 for Pb, respectively. High bio-concentration of Zn (15.37) from soil to spring onion was found at canal water irrigated location. The estimated daily intake of metal for spring onion was less, but the health risk index was higher than 1 for Mo, As, Cu, Pb and Ni, respectively. This was due to higher proportion of spring onion in diet, which consequently increased the health risk index for metals. Therefore, it is recommended to avoid growing vegetables in untreated urban and rural wastewater containing elevated amounts of metals.  相似文献   

Fluvial architecture as a response to two-layer lithospheric subsidence during the Permian and Triassic in the Iberian Basin,eastern Spain     

José López-Gómez  Alfredo Arche  Henar Vargas  Mariano Marzo 《Sedimentary Geology》2010,223(3-4):320-333

The stratigraphy of a sedimentary basin is mainly the result of the long-term response of a depositional surface to prolonged subsidence. However, the real nature of interrelations between fluvial architecture and subsidence is still unknown. Herein, we present new data on these relationships by combining the results of detailed sedimentological field work with data acquired through automated forward modelling and backstripping for the alluvial Permian and Triassic sediments of the SE Iberian Ranges. Using this methodology, we determined tectonic subsidence of the basin by means of backstripping analysis and crust and lithospheric mantle stretching factors (δ and β, respectively) using forward modelling technique. Results indicated that a configuration of two individual and independent layers during lithospheric subsidence for each tectonic phase fit better for this time of the studied basin evolution than the assumption of subsidence due to a single layer spanning the whole lithosphere.For this study, we simplified fluvial geometries as two main types: isolated (I) and amalgamated (A), with subtypes in each case. Different order bounding surfaces (b.s.) were distinguished in the field, although we only selected those affecting the whole basin under study. These included those b.s. of clear tectonic origin, ranging from individual basin boundary-fault pulses produced over periods of approximately 1 My to those arising from major tectonic events, such as the beginning of extension in the basin, causing major changes in basin geometry over periods of 3–5 My.The comparison of δ and β values and fluvial geometries for each identified tectonic phase in the basin evolution, revealed some possible relationship between subsidence and fluvial geometry: Sections showing the most varied fluvial architectural geometries, including ribbon and nested forms, were related to higher β and δ stretching factors values indicating tectonic phases of greater stretching and subsidence. When both stretching factors were similar and close to 1, fluvial geometry was basically reduced to amalgamated geometry type. Wider ranging of fluvial geometries was associated with stages of basin development in which crust and upper mantle activities differed, that is, showing larger differences of β and δ stretching factors values. The related slope changes are proposed as the main surface control of fluvial styles.Combination of subsidence with other possible controlling factors such as avulsion rate, climate or budget of sediments, gives rise to the definitive alluvial architecture of a basin.  相似文献