Influence of rock‐pool characteristics on the distribution and abundance of inter‐tidal fishes          下载免费PDF全文

Gemma E. White  Grant C. Hose  Culum Brown 《Marine Ecology》2015,36(4):1332-1344

Rock pools can be found in inter‐tidal marine environments worldwide; however, there have been few studies exploring what drives their, fish species composition, especially in Australia. The rock‐pool environment is highly dynamic and offers a unique natural laboratory to study the habitat choices, physiological limitations and adaptations of inter‐tidal fish species. In this study rock pools of the Sydney region were sampled to determine how the physical (volume, depth, rock cover and vertical position) and biological (algal cover and predator presence) parameters of pools influence fish distribution and abundance. A total of 27 fish species representing 14 families was observed in tide pools at the four study locations. The five most abundant species were Bathygobius cocosensis, Centropogon australis, Enneapterygius atrogulare, Lepidoblennius haplodactylus and Microcanthus strigatus, which together represented 71% of the total number of fish recorded. Larger rock pools containing more algal and rock ledge cover hosted a larger and more diverse population of fish. Furthermore, certain species were only found in pools with specific characteristics, such as the presence of loose shells, a variety algae or rock cover, suggesting a high degree of habitat specificity. By contrast, some species were ubiquitous and thus can likely tolerate a wide variety of physical conditions.  相似文献   

New morpho-bathymetric data on marine hazard in the offshore of Gulf of Naples (Southern Italy)     

Aiello  Gemma  Sacchi  Marco 《Natural Hazards》2022,111(3):2881-2908

Natural Hazards - Morpho-bathymetric data have been analyzed in order to provide new geological evidence on the Gulf of Naples, i.e., on the southern Ischia slope, on the Naples canyons and on the...  相似文献   

Perceptual models of uncertainty for socio-hydrological systems: a flood risk change example   总被引：2，自引：2，他引：0  

Ida K. Westerberg  Keith J. Beven  Gemma Coxon  Tobias Krueger 《水文科学杂志》2017,62(11):1705-1713

Characterizing, understanding and better estimating uncertainties are key concerns for drawing robust conclusions when analyzing changing socio-hydrological systems. Here we suggest developing a perceptual model of uncertainty that is complementary to the perceptual model of the socio-hydrological system and we provide an example application to flood risk change analysis. Such a perceptual model aims to make all relevant uncertainty sources – and different perceptions thereof – explicit in a structured way. It is a first step to assessing uncertainty in system outcomes that can help to prioritize research efforts and to structure dialogue and communication about uncertainty in interdisciplinary work.  相似文献   

Pockforms: an evaluation of pockmark-like seabed features on the Landes Plateau, Bay of Biscay   总被引：1，自引：1，他引：0  

Jorge Iglesias  Gemma Ercilla  Soledad García-Gil  Alan G. Judd 《Geo-Marine Letters》2010,30(3-4):207-219

Pockmark-like seabed features located on the Landes Plateau, Bay of Biscay, are depressions up to 1 km across and 50 m deep according to multibeam echo sounder data. Seismic (airgun and TOPAS) profiles show that each feature comprises a stack of identical features which extend down to 300 ms (twt). Three types of depressions, elongate, irregular and circular, appear as non-truncating V-shaped features in the Plio-Quaternary sediments. These features are located above the Parentis Basin where deep faults, basement ridges and diapiric bodies extend upwards across the sedimentary cover, providing ideal migration pathways for any buoyant fluids. Initial inspection suggests that these are classic pockmarks; however, the absence of reflection truncation and the absence of indications of shallow gas beneath the features indicate that they were not formed by the removal of sediment. These are “pockforms” but not “pockmarks”. This paper presents an explanation for the formation of these features, involving collapse and subsidence, sedimentary erosion, and only in some cases the erosion of seabed sediments by probable escaping fluids. These origins are mainly conducted through tectonic fluid dynamics which acted in the area up to the Late Miocene. It might be expected that these features would have been infilled by subsequent sedimentation, but their shape has been preserved because sedimentation in the area mainly comprised muds deposited from low-energy transportation (diluted gravity flows) and settling from hemipelagic suspension.  相似文献   

Effects of 17beta-estradiol exposure in the mussel Mytilus galloprovincialis     

Janer G  Lavado R  Thibaut R  Porte C 《Marine environmental research》2004,58(2-5):443-446

Mussels Mytilus galloprovincialis were exposed to different concentrations of estradiol (20, 200, and 2000 ng/l) in a semi-static regime (1-day dosing intervals) for up to 7 days in an attempt to see how mussels dealt with exogenous estrogenic compounds. Sex hormone levels were determined in whole tissue. Free-estradiol was only significantly elevated at the highest exposure dose (up to 10-fold). Most of the estradiol was in the tissues as fatty acid esters (> 78%), which sharply increased in a dose-dependent manner (from 4 ng/g in controls to 258 ng/g at the high exposure group). In contrast, neither free nor esterified testosterone levels showed significant differences between control and exposure groups. The results suggest the existence of mechanisms that allow mussels to maintain their hormonal status, and the important role that fatty acid esterification may play within those mechanisms. Synthesis and conjugation rates of estradiol were further investigated by measuring the activity of P450 aromatase, and palmitoyl-CoA:estradiol acyltransferase, in digestive gland microsomal fractions. Overall, the study contributes to the better knowledge of molluscan endocrinology, and defines new mechanisms of regulation of free steroid-levels in mussels.  相似文献   

Effects of 17β-estradiol exposure in the mussel Mytilus galloprovincialis     

Gemma Janer  Ramon Lavado  Rmi Thibaut  Cinta Porte 《Marine environmental research》2004,58(2-5):443

Mussels Mytilus galloprovincialis were exposed to different concentrations of estradiol (20, 200, and 2000 ng/l) in a semi-static regime (1-day dosing intervals) for up to 7 days in an attempt to see how mussels dealt with exogenous estrogenic compounds. Sex hormone levels were determined in whole tissue. Free-estradiol was only significantly elevated at the highest exposure dose (up to 10-fold). Most of the estradiol was in the tissues as fatty acid esters (>78%), which sharply increased in a dose-dependent manner (from 4 ng/g in controls to 258 ng/g at the high exposure group). In contrast, neither free nor esterified testosterone levels showed significant differences between control and exposure groups. The results suggest the existence of mechanisms that allow mussels to maintain their hormonal status, and the important role that fatty acid esterification may play within those mechanisms. Synthesis and conjugation rates of estradiol were further investigated by measuring the activity of P450 aromatase, and palmitoyl-CoA:estradiol acyltransferase, in digestive gland microsomal fractions. Overall, the study contributes to the better knowledge of molluscan endocrinology, and defines new mechanisms of regulation of free steroid-levels in mussels.  相似文献   

Physical and Geotechnical Properties and Assessment of Sediment Stability on the Continental Slope and Basin of the Bransfield Basin (Antarctica Peninsula)     

D. Casas  G. Ercilla  F. Estrada  B. Alonso  J. Baraza  H. Lee  R. Kayen  F. Chiocci 《Marine Georesources & Geotechnology》2004,22(4):253-278

Our investigation is centred on the continental slope of the Antarctic Peninsula and adjacent basin. Type of sediments, sedimentary stratigraphy, and physical and geotechnical characterization of the sediments have been integrated. Four different types of sediments have been defined: diamictons, silty and muddy turbidites, muddy, silty and muddy matrix embedded clast contourites. There is a close correspondence between the physical properties (density, magnetic susceptibility and p-wave velocity) and the texture and/or fabric as laminations and stratification. From a quantitative point of view, only a few statistical correlations between textural and physical properties have been found. Within the geotechnical properties, only water content is most influenced by texture. This slope, with a maximum gradient observed (20°), is stable, according to the stability under gravitational loading concepts, and the maximum stable slope that would range from 22° to 29°. Nevertheless, different instability features have been observed. Volcanic activity, bottom currents, glacial loading-unloading or earthquakes can be considered as potential mechanisms to induce instability in this area.  相似文献   

Rural tourism in Spain: an analysis of recent evolution   总被引：6，自引：0，他引：6  

Gemma Cnoves  Montserrat Villarino  Gerda K. Priestley  Asuncin Blanco 《Geoforum》2004,35(6):755-769

The aim of this paper is to analyse the evolution of Rural Tourism¹ (RT) in Spain within a European context. The first step is to examine the development of different “models” of RT and trace some experiences of the application of European policy. In order to set the scene and understand this evolution, the collective imagery on which RT is based is also analysed. This is followed by a study of the development of tourist products and services in rural Spain since the 1980s, as diversification of the traditional sun/sand/sea (3S) tourist economy is sought. The analysis underlines the importance of the role of women, and the consequences of the activity for the economy of rural areas. The purpose is to identify differences in the pattern of evolution with more northern European countries, understand their causes and formulate recommendations for future development.  相似文献   

Invasive crayfish as drivers of fine sediment dynamics in rivers: field and laboratory evidence          下载免费PDF全文

Gemma L Harvey  Alexander James Henshaw  Tom P Moorhouse  Nicholas J Clifford  Helen Holah  Jonathan Grey  David W Macdonald 《地球表面变化过程与地形》2014,39(2):259-271

Despite increasing recognition of the potential of aquatic biota to act as ‘geomorphic agents’, key knowledge gaps exist in relation to biotic drivers of fine sediment dynamics at microscales and particularly the role of invasive species. This study explores the impacts of invasive signal crayfish on suspended sediment dynamics at the patch scale through laboratory and field study. Three hypotheses are presented and tested: (1) that signal crayfish generate pulses of fine sediment mobilisation through burrowing and movement that are detectable in the flow field; (2) that such pulses may be more frequent during nocturnal periods when signal crayfish are known to be most active; and (3) that cumulatively the pulses would be sufficient to drive an overall increase in turbidity. Laboratory mesocosm experiments were used to explore crayfish impacts on suspended sediment concentrations for two treatments: clay banks and clay bed substrate. For the field study, high frequency near‐bed and mid‐flow turbidity time series from a lowland river with known high densities of signal crayfish were examined. Laboratory data demonstrate the direct influence of signal crayfish on mobilisation of pulses of fine sediment through burrowing into banks and fine bed material, with evidence of enhanced activity levels around the mid‐point of the nocturnal period. Similar patterns of pulsed fine sediment mobilisation identified under field conditions follow a clear nocturnal trend and appear capable of driving an increase in ambient turbidity levels. The findings indicate that signal crayfish have the potential to influence suspended sediment yields, with implications for morphological change, physical habitat quality and the transfer of nutrients and contaminants. This is particularly important given the spread of signal crayfish across Europe and their presence in extremely high densities in many catchments. Further process‐based studies are required to develop a full understanding of impacts across a range of river styles. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Simple large wood structures promote hydromorphological heterogeneity and benthic macroinvertebrate diversity in low-gradient rivers     

Francesca Pilotto  Gemma L. Harvey  Geraldene Wharton  Martin T. Pusch 《Aquatic Sciences - Research Across Boundaries》2016,78(4):755-766

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