排序方式： 共有30条查询结果，搜索用时 31 毫秒
1.
Florencia Botto Agustina Mendez-Casariego Macarena Valiñas Oscar Iribarne 《Estuaries and Coasts》2008,31(1):134-143
We show that, as previously described, there are conflicts between areas used by people and shorebirds. However, we propose
that burrowing organisms add complexity to the shorebird–human interaction that should be taken into account for management
and conservation. This is because SW Atlantic mudflats are dominated by high densities (up to 60 crabs m−2) of a strong bioturbator, the burrowing crab Neohelice granulata (=Chasmagnathus granulatus). These crabs affect the habitat use and foraging performance of shorebird species. The two-banded plover Charadrius falklandicus feed more in burrow areas whereas the yellowlegs Tringa spp. and the white-rumped sandpiper Calidris fuscicollis tend to avoid burrow areas. We evaluated the effect of human recreational activities on shorebirds, taking into account shorebird–crab
interaction, during shorebird migratory periods (November to April) of 2001, 2002, and 2003. This study was performed at the
Mar Chiquita coastal lagoon (37° 40′ S, Argentina). Results showed that people only rarely used the extensive soft bottom
intertidals dominated by burrowing assemblages of N. granulata because the soft sediments make walking difficult. Therefore, human impact is reduced for the two-banded plover. However,
for several migratory shorebirds that also avoid burrow areas, these areas act as suboptimal alternative areas when human
impact is important in their preferred habitats. When human activity is low, shorebirds remain foraging in the area but they
decrease their feeding intakes. The extensions of burrow areas differ among estuaries and are likely to generate between-estuaries
differences as stopover sites for shorebirds. Also, other species that form large burrowing assemblages can have a similar
impact on shorebird–human interactions. 相似文献
2.
Land managers responsible for invasive species removal in the USA require tools to prevent the Asian longhorned beetle (Anoplophora glabripennis) (ALB) from decimating the maple-dominant hardwood forests of Massachusetts and New England. Species distribution models (SDMs) and spread models have been applied individually to predict the invasion distribution and rate of spread, but the combination of both models can increase the accuracy of predictions of species spread over time when habitat suitability is heterogeneous across landscapes. First, a SDM was fit to 2008 ALB presence-only locations. Then, a stratified spread model was generated to measure the probability of spread due to natural and human causes. Finally, the SDM and spread models were combined to evaluate the risk of ALB spread in Central Massachusetts in 2008–2009. The SDM predicted many urban locations in Central Massachusetts as having suitable environments for species establishment. The combined model shows the greatest risk of spread and establishment in suitable locations immediately surrounding the epicentre of the ALB outbreak in Northern Worcester with lower risk areas in suitable locations only accessible through long-range dispersal from access to human transportation networks. The risk map achieved an accuracy of 67% using 2009 ALB locations for model validation. This model framework can effectively provide risk managers with valuable information concerning the timing and spatial extent of spread/establishment risk of ALB and potential strategies needed for effective future risk management efforts. 相似文献
3.
Florencia Botto Esteban Gaitán Hermes Mianzan Marcelo Acha Diego Giberto Agustín Schiariti Oscar Iribarne 《Estuarine, Coastal and Shelf Science》2011
The Río de la Plata (34° 36′ S, 55° 58′ W; Argentina and Uruguay) estuary, one of the most important South American estuarine environments, is characterized by weak seasonal freshwater discharge, low tidal amplitude (<1 m), a wide and permanent connection to the sea, and a salt-wedge regime. Using stable isotope analysis, we explored the relative importance of the different sources of primary production in the food web. Our results show that phytoplankton and macrodetritus from terrestrial salt and freshwater marshes both contribute to the food web of the Río de la Plata estuary. On the basis of the sampled species, we identified four trophic levels. The clam Mactra isabelleana, the calanoid copepod Acartia tonsa, and the opossum shrimp Neomysis americana are the primary consumers. The rays Atlantoraja castelnaui and Squatina guggenheim and the shark Galeorhinus galeus are the top predators. The Río de la Plata food web shows an important input of nutrients derived from phytoplankton. Rays, sharks, and predatory gastropods reveal an important contribution of C4 plants (likely Spartina spp.). However, production derived from C3 plants is also important for some species. The fishes Brazilian menhaden, Brevoortia aurea; the stripped weakfish Cynoscion guatucupa; and the whitemouth croaker, Micropogonias furnieri, showed differences in their isotopic signatures as juveniles and adults, indicating different food sources, and they were therefore treated as different components of the food web. Our data suggest that detritus from salt and freshwater marshes is reaching the Río de la Plata estuary and can be an important allocthonous source of energy to this environment. 相似文献
4.
Alejandro?D.?Canepuccia Maria?S.?Fanjul Eugenia?Fanjul Florencia?Botto Oscar?O.?Iribarne Consejo Nacional de Investigaciones Científicas y Técnicas Departamento de Biología Universidad Nacional de Mar del Plata Mar del Plata Argentina 《Estuaries and Coasts》2008,31(5):920-930
The role of positive and indirect interactions is often crucial in communities with intense abiotic stress such as salt marshes.
The burrowing crab, Neohelice (=Chasmagnathus) granulata, is the dominant benthic macroinvertebrate of southwest Atlantic marshes (southern Brazil to Northern Argentinean Patagonia),
having strong direct and indirect effects on marsh soil and, in consequence, on marsh vegetation and primary consumers. In
this work, we investigate if this crab indirectly modifies habitat use by the granivorous rodents, Akodon azarae and Oligoryzomys flavescens, by increasing nutrient availability and thus enhancing seed production by the marsh plant Spartina densiflora. The study was conducted at the Mar Chiquita Coastal Lagoon, Argentina (37°32′ S). Rodent frequencies in S. densiflora were positively correlated with crab densities throughout the low and middle marsh. Additionally, the highest quality of
S. densiflora and inflorescence density was recorded at the highest crab densities. Experimental manipulation of crab densities shows that
N. granulata indirectly enhances the performance of S. densiflora (e.g., decreased fiber content and C/N ratios) and increases density of seeds. Moreover, N. granulata also facilitates S. densiflora seed availability to rodents by concentrating them in sediment mound at their burrows entrances. Experimental rodent exclusions
showed that rodent species used S. densiflora seeds, a variable positively related to crab burrow density. Thus, our results show that N. granulata drives the granivorous rodent distribution and the intensity of seeds–rodent interaction trough facilitative and indirect
interactions in marsh community. 相似文献
5.
6.
Menone ML Miglioranza KS Botto F Iribarne O Aizpún de Moreno JE Moreno VJ 《Marine pollution bulletin》2006,52(12):1717-1724
The influence of intertidal crab beds on the concentrations of organochlorine (OC) pesticides in sediment was studied in two different coastal environments in Argentina. Samples of male burrowing crabs (Chasmagnathus granulatus) were collected for this study. Our field data showed lower bioaccumulation of OC pesticides in crabs from sediments with a higher total organic carbon (TOC) and higher clay content. Thus, concentrations in crabs depend on the physico-chemical characteristics of the sediment where they live more than on the OC pesticide concentrations in the environment. The distribution patterns in sediment from inside and outside crab burrows were similar for both coastal areas being HCHs γ-chlordane > p,p′-DDE for San Antonio Bay (SAO), and HCHs > p,p′-DDE γ-chlordane for Mar Chiquita (MCh) coastal lagoon. OC pesticide concentrations in sediment were significantly lower inside than outside crab burrows, irrespective of the sediment physico-chemical characteristics due to the bioturbation activity of C. granulatus. 相似文献
7.
Florencia Bechis Laura Giambiagi Víctor García Silvia Lanés Ernesto Cristallini Maisa Tunik 《Journal of Structural Geology》2010,32(7):886-899
The Atuel depocenter of the Neuquén basin originated as an Upper Triassic to Lower Jurassic rift system, later inverted during the Andean contractional deformation. In order to study the extensional architecture and the kinematic evolution of this depocenter, we collected a large amount of field and sub-surface data, consisting of slip data from outcrop-scale normal faults, thickness and facies distribution within the synrift deposits, and structural data from angular and progressive unconformities. The Atuel depocenter has a NNW trend, showing a bimodal distribution of NNW and WNW major faults (first and second order faults). On the other hand, from kinematic indicators measured on outcrop-scale faults (third and fourth order faults), we found a mean NE internal extension direction, which is oblique to the general trend of the sub-basin. Taking these particular characteristics into account, we interpreted the Atuel depocenter as an oblique rift system. We evaluated two mechanisms in order to explain the development of this transtensional system: 1) reactivation of upper-crustal NNW-oriented Paleozoic shear zones, and 2) oblique stretching of a previous NNW-oriented lithospheric weakness zone. 相似文献
8.
Florencia Botto Gabriela Palomo Oscar Iribarne Mariano M. Martinez 《Estuaries and Coasts》2000,23(2):208-215
Southwestern Atlantic estuaries (Southern Brazil to Northern Patagonia, Argentina) are characterized by the presence of an intertidal burrowing crab Chasmagnathus granulata. This crab species is an important bioturbator which lives in large assemblages and excavates semi-permanent burrows that affect sediment characteristics. Our observations showed that distribution of the crabs in the Mar Chiquita coastal lagoon, Argentina (37°45′S, 57°26′W) affected habitat use and feeding success of migratory shorebirds. During the migratory season the two-banded plover (Charadrius falklandicus) foraged more frequently inside crab beds, and yellowlegs (Tringa flavipes and T. melanoleuca) fed more freqeuntly outside crab beds. Focal observations on the feeding behavior of the white-rumped sandpiper (Calidris fuscicollis) and the two-banded plover inside and outside crab beds showed that the plover was a visual searcher and captured more prey inside crab beds, and the white-rumped sandpiper was a tactile feeder. Although consumption rates (prey min?1) did not differ between sites, their efficiency (prey probe?1) inside crab beds was less. These differences were probably related to changes in sediment characteristics and prey behavior, which vary with crab activity. Burrowing crabs alter the suitability of intertidal habitats used by shorebirds in southwestern Atlantic estuaries. We believe that the same process could be occurring with other burrowing curstaceans such as thalassinidean shrimps in other estuaries of the world and could have important implications for management of flats for shorebirds. *** DIRECT SUPPORT *** A01BY090 00007 相似文献
9.
Shunso ISHIHARA Hiroyasu MURAKAMI Maria Florencia MARQUEZ‐ZAVALIA 《Resource Geology》2011,61(2):174-191
Tin‐polymetallic base metal deposits of Miocene age in the Eastern Cordillera in Bolivia were studied by ICP/MS and EPMA for major and minor elements, paying an attention to indium concentration of the ore deposits. The highest indium content and 1000 In/Zn ratio of individual ore deposits are 5,740 ppm and 22.2 for the Potosi deposits, 2,730 ppm and 7.4 for Bolivar deposit, 2,510 ppm and 17.5 for Siete Suyos–Animas deposits, and 1,290 ppm and 3.3 for San Vicente deposit. The same content and ratio of composite samples of the studied deposits are up to 292 ppm and 4.0 for Potosi deposits, 3,080 ppm and 11.3 for Huari Huari deposit, 100 ppm and 0.3 for Tuntoco deposit, 152 ppm and 1.8 for Porco deposit, 103 ppm and 59.2 for Animas deposit, and 1,160 ppm and 3.7 for Pirquitas deposit. Those of zinc concentrates are as follows: 1,080 ppm and 2.1 at San Lorenzo; 584 ppm and 1.7 at Bolivar; 499 ppm and 1.23 at Porco; 449 ppm and 1.21 at Reserva, and 213 ppm and 0.61 at Colquiri deposit. Indium occurs mostly in dark colored sphalerite and that of the Potosi deposit was found to have one of the highest concentrations, containing up to 1.27 wt% In. Petrukite was discovered in the Potosi deposit, and indium minerals are expected to occur in the Huari Huari deposit and others with the high 1000 In/Zn ratios. The indium contents of the zinc concentrates and composite samples were applied to the produced and remaining ores, then the total amounts of indium in the Bolivian tin‐polymetallic base metal deposits are speculated to be more than 12,000 tons In, which is bigger than that of South China (11,000 tons) and the Japanese Islands (9,000 tons). Sphalerites of the Potosi deposit have one of the highest ranges of indium, similarly to those of the San Vicente deposit. Both the San Vicente and Potosi deposits are rich in silver, implying significance of both silver‐polymetallic and tin‐polymetallic environments for the concentration of trace amounts of indium. 相似文献
10.
Florencia Arrighetti Thomas Brey Andreas Mackensen Pablo E. Penchaszadeh 《Journal of Sea Research》2011,65(2):219-223
The marine subtidal volutid snail Adelomelon beckii was studied in order to obtain their population dynamics, particularly on growth, age, mortality and production. Stable oxygen isotope ratios confirmed semiannual formation of internal growth marks. A von Bertalanffy growth model fitted 308 size-at-age data pairs. A. beckii potential lifespan in Mar del Plata (Argentina) region is 29 years, being rather long lived compared to other large gastropods. Total mortality Z and natural mortality M were calculated to be 0.210 y?1 and 0.081 y?1 respectively. Fishing mortality F amounts to 0.129 y?1 corresponding to an exploitation rate E of 0.614, a value much beyond the optimum rate of 0.427. The current exploitation regime will be unsustainable in the long run unless a proper management approach establishes. 相似文献