Corrigendum to: Partitioning spatial and temporal variability of tropical near-shore macrobenthic assemblages affected by natural and anthropogenic disturbances

2011 ◽  
Vol 62 (7) ◽  
pp. 885
Author(s):  
P. Rodríguez-Pliego ◽  
H. A. Hernández-Arana ◽  
P.-L. Ardisson

Coastal zones throughout the world are subject to natural and anthropogenic disturbances that modify the natural assemblages. The present study determined the response of the assemblage of macrobenthic invertebrates to the presence of a pier and natural climatic variations. Two analytical models were considered; one was an asymmetric model that permitted the comparison of the sector closest to the pier (impact) with the average of the sectors located further away (controls); the other was a three-way model that enabled the three sectors within the area to be analysed. With both models, the differences were compared among the sampling periods and the scale at which the variation in the data was greatest. No differences were detected among individual sectors or between the control and impact sectors. However, significant differences were found among the four periods. The zone closest to the pier presented greater temporal variability. This relationship suggests that the pier affecting the assemblage and the impact may be increased by the climatic conditions prevalent in the zone. It is necessary to establish a broader temporal analysis and a more detailed analysis of the structure and composition of the benthic assemblage to elucidate this temporal and spatial variability.

2011 ◽  
Vol 62 (4) ◽  
pp. 342 ◽  
Author(s):  
P. Rodríguez-Pliego ◽  
H. A. Hernández-Arana ◽  
P.-L. Ardisson

Coastal zones throughout the world are subject to natural and anthropogenic disturbances that modify the natural assemblages. The present study determined the response of the assemblage of macrobenthic invertebrates to the presence of a pier and natural climatic variations. Two analytical models were considered; one was an asymmetric model that permitted the comparison of the sector closest to the pier (impact) with the average of the sectors located further away (controls); the other was a three-way model that enabled the three sectors within the area to be analysed. With both models, the differences were compared among the sampling periods and the scale at which the variation in the data was greatest. No differences were detected among individual sectors or between the control and impact sectors. However, significant differences were found among the four periods. The zone closest to the pier presented greater temporal variability. This relationship suggests that the pier affecting the assemblage and the impact may be increased by the climatic conditions prevalent in the zone. It is necessary to establish a broader temporal analysis and a more detailed analysis of the structure and composition of the benthic assemblage to elucidate this temporal and spatial variability.


2004 ◽  
Vol 8 (3) ◽  
pp. 449-459 ◽  
Author(s):  
I. A. Malcolm ◽  
D. M. Hannah ◽  
M. J. Donaghy ◽  
C. Soulsby ◽  
A. F. Youngson

Abstract. The spatio-temporal variability of stream water temperatures was investigated at six locations on the Girnock Burn (30km2 catchment), Cairngorms, Scotland over three hydrological years between 1998 and 2002. The key site-specific factors affecting the hydrology and climatology of the sampling points were investigated as a basis for physical process inference. Particular emphasis was placed on assessing the effects of riparian forest in the lower catchment versus the heather moorland riparian zones that are spatially dominant in the upper catchment. The findings were related to river heat budget studies that provided process detail. Gross changes in stream temperature were affected by the annual cycle of incoming solar radiation and seasonal changes in hydrological and climatological conditions. Inter-annual variation in these controlling variables resulted in inter-annual variability in thermal regime. However, more subtle inter-site differences reflected the impact of site-specific characteristics on various components of the river energy budget. Inter-site variability was most apparent at shorter time scales, during the summer months and for higher stream temperatures. Riparian woodland in the lower catchment had a substantial impact on thermal regime, reducing diel variability (over a period of 24 hours) and temperature extremes. Observed inter-site differences are likely to have a substantial effect on freshwater ecology in general and salmonid fish in particular. Keywords: temperature, thermal regime, forest, salmon, hydrology, Girnock Burn, Cairngorm


2018 ◽  
Vol 66 (1) ◽  
pp. 57 ◽  
Author(s):  
Natalie J. Clark ◽  
Courtenay E. Mills ◽  
Nicolette A. Osborne ◽  
Kerry M. Neil

Development of water infrastructure benefits water security and agriculture but poses risks to habitat and aquatic fauna. Wyaralong Dam was constructed on Teviot Brook in 2010 to provide future urban water supplies for South East Queensland, Australia. Construction of the dam created a large impoundment area and environmental impact assessment predicted significant impacts upon resident freshwater turtle species and their habitats. Differences in habitat requirements, life-history characteristics and sensitivity to change between the Macquarie River turtle (Emydura macquarii macquarii) and the common saw-shelled turtle (Myuchelys latisternum) were expected to influence the impact of the dam on the spatial and temporal abundance of these species. The relative abundance of each species was monitored at sites located within, upstream and downstream of the impoundment across wet and dry seasons during the dam’s first five years of operation. The results of this monitoring program indicate that spatial and temporal variability in the relative abundance of E. macquarii macquarii and M. latisternum occurred during the study but not all expected impacts were realised. Contrary to expectation, the relative abundance of E. macquarii macquarii did not increase over time within, upstream or downstream of the dam. M. latisternum showed greater temporal variability at some sites; however, no clear relationship between relative abundance and operational years was observed during the monitoring program. Spatial variability in relative abundance between sites was dependent upon season, with trends generally consistent across both turtle species. Where differences between species were observed, these are suspected to have resulted from the influence of environmental conditions on species-specific movement behaviours. The monitoring program confirmed the use of the upper limits of the impoundment and the plunge pool below the dam wall by both turtle species but relative abundance within the main body of the impoundment remained low throughout monitoring. The results of the study allow for consideration of the suitability of predefined management measures and the development of recommendations for future monitoring programs prescribed for water infrastructure developments.


2019 ◽  
Vol 58 ◽  
pp. 145-152
Author(s):  
Ganesh Kumar Jimee ◽  
Kimiro Meguro ◽  
Amod Mani Dixit

Nepal, though covers small area of the earth, exposes complex geology with active tectonic processes, high peaks, sloppy terrain and climatic variation. Combination of such geo-physical and climatic conditions with existing poor socio-economic conditions, unplanned settlements, rapidly increasing population and low level of awareness has put the country in highest risk to multi-hazard events. Fires, floods, landslides and epidemics are the most frequent hazard events, which have cumulatively caused a significant loss of lives and property every year. However, due to diversity in physiographic, climatic and socio-economic conditions within the country, the type, frequency and degree of the impact of such events differs in different places. During the period of 46 years (1971-2016), an average of 2 events have been occurred causing 3 deaths/missing every day. Disaster events occurred most frequently during the months of April, July and August, while relatively lesser number of events have been reported during January, November and December. However, earthquakes have been reported in different months, regardless with the season. This paper is an effort to analyse the spatial distribution and temporal variation of disaster events in Nepal. Further it has drawn a trend of disasters occurrence in Nepal, which will help the decision makers and other stakeholders for formulating Disaster Risk Management (DRM) plan and policies on one hand and heighten citizens’ awareness of against disasters on the other.


2003 ◽  
Vol 54 (8) ◽  
pp. 1009 ◽  
Author(s):  
Shaun N. Meredith ◽  
Vladimir F. Matveev ◽  
Paul Mayes

The diurnal distribution and diet of Hypseleotris spp. was examined over a 14-month period in Maroon Dam, a productive subtropical reservoir in south-east Queensland, Australia. Three distinct size classes of Hypseleotris were observed. The smallest (<16 mm standard length (SL)) fish undertake a vertical diurnal migration in the pelagic throughout the year, spending daylight hours near the surface and night hours in deeper waters. The diet of this size class consists almost exclusively of zooplankton (98.6% total prey volume), with cladocera and copepoda dominating the identifiable prey items. A larger (12–20 mm SL) size class group of subadult/adult fish occupies the near-shore littoral throughout the daylight hours but moves out of the sampled area during the night. The diet of this size class is more diverse (zooplankton 58.5%, macro-invertebrate 25.0%, other 16.5%). The largest size class (>20 mm SL) of adult Hypseleotris remains in the near-shore littoral throughout seasonal and diurnal cycles and has a more eclectic diet than the other two size classes (zooplankton 28.8%, macro-invertebrate 28.9%, other 42.3%). Spatial and temporal differences in the distribution and diet of these three size class groups are discussed with reference to the abundance and availability of suitable prey, intraspecific competitive exclusion, predator avoidance and water quality.


Author(s):  
XAVIER DURRIEU de MADRON ◽  
MARION STABHOLZ ◽  
LARS-ERIC HEIMBÜRGER-BOAVIDA ◽  
DOMINIQUE AUBERT ◽  
PHILIPPE KERHERVÉ ◽  
...  

Dense shelf water cascading and open-ocean convection frequently occurs in the Gulf of Lions, northwestern Mediterranean Sea. These intense dense water formation events are capable of supplying large amounts of particulate matter as well as remobilizing and dispersing local sediments and, therefore, are thought to leave an imprint on superficial deposits. Here, we compared the spatial variability of the superficial sediment composition (grain size, organic parameters, and metals) at different scales (from decimetric to kilometric) on the continental slope and rise with the temporal variability linked to the occurrence of intense dense water formation events. The spatial and temporal variability of the geochemical composition of deep sediments was assessed using multivariate and geostatistical analysis. The results indicate that, on the outer reach of the Cap de Creus Canyon, where both processes interact, no clear relation was found between the temporal variability of the superficial sediment and the deep-water formation events, and that the small-scale spatial variability of the sediment is masking the temporal variability. Measurements across the southern slope indicate the presence of a somehow distinct geochemical signature that likely results from the influence of recurrent intense, dense water formation events as well as an unabating bottom trawling activity.


2017 ◽  
Author(s):  
Casey A. Joseph ◽  
Derrick J. Lampkin

Abstract. The impact of melt water injection into ice streams over the Greenland Ice Sheet is not well understood. Water-filled crevasses along the shear margins of Jakobshavn Isbræ are known to fill and drain, resulting in weakening of the shear margins due to reduced basal friction. Seasonal variability in the hydrologic dynamics of these features has not been quantified. In this work, we characterize the spatial and temporal variability in the hydrological state (filled or drained) of these water-filled crevasse systems. A fusion of multi-sensor optical satellite imagery was used to examine hydrologic states from 2000 to 2015. The monthly distribution of crevasse systems observed as water filled is unimodal with peak number of filled days during the month of July at 329 days, while May has the least at 15. Over the study period the occurrence of drainage within a given season increases. Inter-seasonal drain frequencies over these systems ranged from 0 to 5. The frequency of multi-drainage events are correlated with warmer seasons and large strain rates. Over the study period, summer temperatures averaged from −1 and 2 °C and tensile strain rates have increased to as high as ~ 1.2 s-1. Intermittent melt water input during hydrofracture drainage responsible for transporting surface water to the bed is largely facilitated by high local tensile stresses. Drainage due to fracture propagation may be increasingly modulated by ocean-induced calving dynamics for the lower elevation ponds. Water-filled crevasses could expand in extent and volume as temperatures increase resulting in regional amplification of ice mass flux into the ice stream system.


2016 ◽  
Vol 38 ◽  
pp. 209
Author(s):  
Cláudio Alberto Teichrieb ◽  
Pablo Eli Soares de Oliveira ◽  
Tamires Zimmer ◽  
Cristiano Maboni ◽  
Daniel Michelon dos Santos ◽  
...  

In the last 15-20 years has greatly increased research on the problem of climate change, necessitating a demand for reliable measurements of absorption and emission of carbon dioxide, methane, as well as the impact on water resources. In the biome Pampa are the largest continuous natural field extensions, requiring a monitoring of water and temperature regime on the ground. The water content of the soil has spatial and temporal variability affecting many hydrological processes and determining this is needed since the soil store and provide the water and nutrients for the plants, thus involving relationships water-soil-plant-atmosphere. In this work, we compared the water content behavior of the soil at depths of 10, 30 and 50 cm, the temperature of the soil at depths of 5, 15 and 30 cm, heat flux in soil installed 10 cm deep and the thermal conductivity was determined in two experimental sites in the Pampa biome, for the period 01.01.2015 to 06.31.2015. It was found that there are differences between the sites in the capacity to retain moisture in the soil and in the ability to store energy in the soil for the study period.


2020 ◽  
Vol 8 (9) ◽  
pp. 676
Author(s):  
Eva Leu ◽  
Thomas A. Brown ◽  
Martin Graeve ◽  
Jozef Wiktor ◽  
Clara J. M. Hoppe ◽  
...  

Assessing the relative importance of sea ice algal-based production is often vital for studies about climate change impacts on Arctic marine ecosystems. Several types of lipid biomarkers and stable isotope ratios are widely used for tracing sea ic-associated (sympagic) vs. pelagic particulate organic matter (POM) in marine food webs. However, there has been limited understanding about the plasticity of these compounds in space and time, which constrains the robustness of some of those approaches. Furthermore, some of the markers are compromised by not being unambiguously specific for sea ice algae, whereas others might only be produced by a small sub-group of species. We analyzed fatty acids, highly branched isoprenoids (HBIs), stable isotope ratios of particulate organic carbon (POC) (δ13C), as well as δ13C of selected fatty acid markers during an Arctic sea ice algal bloom, focusing on spatial and temporal variability. We found remarkable differences between these approaches and show that inferences about bloom characteristics might even be contradictory between markers. The impact of environmental factors as causes of this considerable variability is highlighted and explained. We emphasize that awareness and, in some cases, caution is required when using lipid and stable isotope markers as tracers in food web studies and offer recommendations for the proper application of these valuable approaches.


2018 ◽  
Vol 58 (4) ◽  
pp. 473-485
Author(s):  
A. Y. Komarov ◽  
Y. G. Seliverstov ◽  
P. B. Grebennikov ◽  
S. A. Sokratov

Te paper presents the results of studies aimed at investigation of the spatial and temporal variability of snow coverstructure on the basis of strength values and its variations obtained by means of the high-resolution penetrometer SnowMicroPen. Te possibilities of fast and independent from the observer identifcation of layers (including identifcation of weakened, potentially avalanche-dangerous layers) were estimated under the climatic conditions of Moscow and the Khibiny mountains. Horizontal areas with homogeneous underlying surface and vegetation were selected for the stratigraphic studies that made it possible to avoid a possible influence of slope relief and exposure from the obtained data on the spatial and temporal variability of the snow depth structure. Te analysis of the information obtained in winter seasons 2014/15 and 2016/17 allowed constructing detailed schemes of the snow cover evolution at the Moscow site as well as assessing the inter-annual and intra-seasonal variability of its structure. Afer the SnowMicroPen data were recorded in the course of the feld works carried out in winter 2015/16 on the Khibiny educational and scientifc base of the Lomonosov Moscow State University (city of Kirovsk), the 10-meter trench on the same profle was described in details, and direct data on the snow cover structure were obtained. Te strength values resulted from the above studies characterize the layers composed of crystals of various shapes and sizes, and they are considered as the frst step to methodology of operational defnition of the spatially-inhomogeneous stratigraphy and stability of snowpack without snowpit observations. Te data analysis showed high spatial and temporal variability of the structure and properties of snow cover even at a homogeneous area, usually described by a single snowpit.


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