scholarly journals Multiple Evidence for Climate Patterns Influencing Ecosystem Productivity across Spatial Gradients in the Venice Lagoon

2021 ◽  
Vol 9 (4) ◽  
pp. 363
Author(s):  
Camilla Bertolini ◽  
Edouard Royer ◽  
Roberto Pastres
Keyword(s):  
Time Series ◽  
Primary Productivity ◽  
Clustering Analysis ◽  
Venice Lagoon ◽  
Spatial Effects ◽  
Spatial Gradients ◽  
Climate Forecasting ◽  
Oxygen Production Rate ◽  
Temporal And Spatial

Effects of climatic changes in transitional ecosystems are often not linear, with some areas likely experiencing faster or more intense responses, which something important to consider in the perspective of climate forecasting. In this study of the Venice lagoon, time series of the past decade were used, and primary productivity was estimated from hourly oxygen data using a published model. Temporal and spatial patterns of water temperature, salinity and productivity time series were identified by applying clustering analysis. Phytoplankton and nutrient data from long-term surveys were correlated to primary productivity model outputs. pmax, the maximum oxygen production rate in a given day, was found to positively correlate with plankton variables measured in surveys. Clustering analysis showed the occurrence of summer heatwaves in 2008, 2013, 2015 and 2018 and three warm prolonged summers (2012, 2017, 2019) coincided with lower summer pmax values. Spatial effects in terms of temperature were found with segregation between confined and open areas, although the patterns varied from year to year. Production and respiration differences showed that the lagoon, despite seasonality, was overall heterotrophic, with internal water bodies having greater values of heterotrophy. Warm, dry years with high salinity had lower degrees of summer autotrophy.

scholarly journals Long-term variability of storm surge frequency in the Venice Lagoon: an update thanks to 18th century sea level observations

2015 ◽  
Vol 15 (3) ◽  
pp. 527-535 ◽  
Author(s):  
F. Raicich
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Storm Surge ◽  
18Th Century ◽  
Venice Lagoon ◽  
Mean Sea Level ◽  
Sea Level Anomalies ◽  
Daily Data ◽  
Remarkable Event

Abstract. Sea level observations made in the Venice Lagoon between 1751 and 1792 have been recovered, consisting of two time series of daily data on high and low waters in Venice and Chioggia. From comparisons with modern observations, the quality of the 18th century data appears to be good enough to allow a useful analysis. A composite time series of daily mean sea level is obtained by merging the 18th century data and 1872–2004 observations in Venice Punta della Salute. The absence of reliable information on vertical references prevents the connection of the two 18th century time series with each other and with modern observations. However, daily sea level anomalies relative to the mean sea level enable us to recognize storm surge events that appear to occur more frequently in the second half of the 18th century than in the late 19th and 20th centuries, particularly during the 1751–1769 period. The record-breaking storm surge of 4 November 1966 turns out to be a remarkable event even in comparison to the events extracted from the 18th century time series. Further work is required to fill the gap between the old and modern observations.

scholarly journals Long-term spatiotemporal stability and dynamic changes in helminth infracommunities of spiny mice (Acomys dimidiatus) in St. Katherine's Protectorate, Sinai, Egypt

Parasitology ◽  
2018 ◽  
Vol 146 (1) ◽  
pp. 50-73
Author(s):  
Jerzy M. Behnke ◽  
Anna Bajer ◽  
Jolanta Behnke-Borowczyk ◽  
Natalie Clisham ◽  
Francis Gilbert ◽  
...  
Keyword(s):  
Rank Order ◽  
Spatial Effects ◽  
Spiny Mice ◽  
Age Dependent ◽  
Female Bias ◽  
Temporal And Spatial ◽  
Host Evolution ◽  
Host Parasite ◽  
Acomys Dimidiatus

AbstractThe importance of parasites as a selective force in host evolution is a topic of current interest. However, short-term ecological studies of host–parasite systems, on which such studies are usually based, provide only snap-shots of what may be dynamic systems. We report here on four surveys, carried out over a period of 12 years, of helminths of spiny mice (Acomys dimidiatus), the numerically dominant rodents inhabiting dry montane wadis in the Sinai Peninsula. With host age (age-dependent effects on prevalence and abundance were prominent) and sex (female bias in abundance in helminth diversity and in several taxa including Cestoda) taken into consideration, we focus on the relative importance of temporal and spatial effects on helminth infracommunities. We show that site of capture is the major determinant of prevalence and abundance of species (and higher taxa) contributing to helminth community structure, the only exceptions beingStreptopharausspp. andDentostomella kuntzi.We provide evidence that most (notably the Spiruroidea,Protospirura muricola,Mastophorus murisandGongylonema aegypti, but with exceptions among the Oxyuroidae, e.g.Syphacia minuta), show elements of temporal-site stability, with a rank order of measures among sites remaining similar over successive surveys. Hence, there are some elements of predictability in these systems.

scholarly journals Long-term variability of storm surge frequency in the Venice Lagoon: an update thanks to eighteenth century sea level observations

2014 ◽  
Vol 2 (12) ◽  
pp. 7465-7486
Author(s):  
F. Raicich
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Storm Surge ◽  
18Th Century ◽  
Venice Lagoon ◽  
Mean Sea Level ◽  
Sea Level Anomalies ◽  
Daily Data ◽  
Remarkable Event

Abstract. Sea level observations made in the Venice Lagoon between 1751 and 1792 have been recovered, consisting of two time series of daily data on high and low waters at Venice and Chioggia. From comparisons with modern observations the quality of the 18th century data appears to be good enough to allow a useful analysis. A composite time series of daily mean sea level is obtained by merging the 18th century data and 1872–2004 observations at Venice Punta della Salute. The absence of reliable information on vertical references prevents the connection of the two 18th century time series with each other and with modern observations. However, daily sea level anomalies relative to the mean sea level enable to recognize storm surge events, that appear to occur more frequently in the second half of the 18th century than in the late 19th and 20th centuries, particularly during the 1751–1769 period. The record-breaking storm surge of 4 November 1966 turns out to be a remarkable event also in comparison with the events extracted from the 18th century time series. Further work is required to fill the gap between the old and modern observations.

Primary productivity in a coastal ecosystem: a trophic perspective on a long-term time series

2015 ◽  
Vol 38 (4) ◽  
pp. 1092-1102 ◽  
Author(s):  
Peter Tiselius ◽  
Andrea Belgrano ◽  
Lars Andersson ◽  
Odd Lindahl
Keyword(s):  
Time Series ◽  
Primary Productivity ◽  
Coastal Ecosystem

scholarly journals Variations in and environmental controls of primary productivity in the Amundsen Sea

2021 ◽  
Author(s):  
Jianlong Feng ◽  
Delei Li ◽  
Jing Zhang ◽  
Liang Zhao
Keyword(s):  
Primary Production ◽  
Primary Productivity ◽  
Sea Surface ◽  
Iron Nitrate ◽  
Amundsen Sea ◽  
Dissolved Iron ◽  
Environmental Controls ◽  
Long Term Changes ◽  
Temporal And Spatial

Abstract. The Amundsen Sea is one of the regions with the highest primary productivity in the Antarctic. To better understand the role of the Southern Ocean in the global carbon cycle and in climate regulation, a better understanding of the variations in and environmental controls of primary productivity is needed. Using cluster analysis, the Amundsen Sea was divided into nine bioregions. The biophysical differences among bioregions enhanced confidence to identify priorities and regions to study the temporal and spatial variations in primary productivity. Four nearshore bioregions with high net primary productivity or rapidly increasing rates were selected to analyze temporal and spatial variations in primary productivity in the Amundsen Sea. Due to changes in net solar radiation and sea ice, primary production had significant seasonal variation in these four bioregions. The phenology had changed at two bioregions (3 and 5), which has the third and fourth highest primary production, due to changes in the dissolved iron, nitrate, phosphate, and silicate concentrations. Annual primary production showed increasing trends in these four bioregions. The variation in primary production in the bioregion (9), which has the highest primary production, was mainly affected by variations in sea surface temperatures. In the bioregion, which has the second-highest primary production (8), the primary production was significantly positively correlated with sea surface temperature and significantly negatively correlated with sea ice thickness. The long-term changes of primary productivity in bioregions 3 and 5 were thought to be related to changes in the dissolved iron, nitrate, phosphate, and silicate concentrations, and dissolved iron was the limiting factor in these two bioregions. Bioregionalization not only disentangle multiple factors that control the spatial differences, but also disentangle limiting factors that affect the phenology, decadal and long-term changes in primary productivity.

scholarly journals Interpretation of interannual variability in long-term aquatic ecological surveys

2020 ◽  
Vol 77 (5) ◽  
pp. 894-903 ◽  
Author(s):  
Sophie Cauvy-Fraunié ◽  
Verena M. Trenkel ◽  
Martin Daufresne ◽  
Anthony Maire ◽  
Hervé Capra ◽  
...  
Keyword(s):  
Time Series ◽  
Interannual Variability ◽  
Environmental Effects ◽  
Statistical Power ◽  
River Estuary ◽  
Observation Time ◽  
Sampling Effort ◽  
Spatial Effects ◽  
Sampling Uncertainty

Long-term ecological surveys (LTES) often exhibit strong variability among sampling dates. The use and interpretation of such interannual variability is challenging due to the combination of multiple processes involved and sampling uncertainty. Here, we analysed the interannual variability in ∼30 years of 150 species density (fish and invertebrate) and environmental observation time series in four aquatic systems (stream, river, estuary, and marine continental shelf) with different sampling efforts to identify the information provided by this variability. We tested, using two empirical methods, whether we could observe simultaneous fluctuation between detrended time series corresponding to widely acknowledged assumptions about aquatic population dynamics: spatial effects, cohort effects, and environmental effects. We found a low number of significant results (36%, 9%, and 0% for spatial, cohort, and environmental effects, respectively), suggesting that sampling uncertainty overrode the effects of biological processes. Our study does not question the relevance of LTES for detecting important trends, but clearly indicates that the statistical power to interpret interannual variations in aquatic species densities is low, especially in large systems where the degree of sampling effort is always limited.

Analysis of long-term catchment data: a nonlinear perspective

2020 ◽  
Author(s):  
Holger Lange ◽  
Michael Hauhs ◽  
Katharina Funk ◽  
Sebastian Sippel ◽  
Henning Meesenburg
Keyword(s):  
Time Series ◽  
Temporal Resolution ◽  
Forest Growth ◽  
Scaling Behavior ◽  
Permutation Entropy ◽  
Data Sets ◽  
Detailed Model ◽  
Spatial Gradients ◽  
Visibility Graphs

<p>We analyze time series from several forested headwater catchments located adjacent to each other in the Bramke valley, Harz mountains (Germany) which are monitored since decades for hydrology, hydrochemistry and forest growth. The data sets include meteorological variables, runoff rates, streamwater chemical concentrations, and others. The basic temporal resolution is daily for hydrometeorology and two-weekly for streamwater chemistry (in addition, standing biomass of a Norway spruce stand is measured every couple of years).</p><p>A model was calibrated and run for the streamflow from one of the catchments, based on precipitation, temperature and (simulated) evapotranspiration of the growing trees, to elucidate the effect of forest growth on catchment hydrology.</p><p>The catchments exhibit long-term changes and spatial gradients related to atmospheric deposition, management and changing climate. After providing a short multivariate summary of the dataset, we present several nonlinear metrics suitable to detect and quantify subtle changes and to describe different behavior, both between different variables from the same catchment, as well as for the same variable across catchments. The methods include, but are not limited to: Tarnopolski analysis, permutation entropy and complexity, q- and α-complexities, and Horizontal Visibility Graphs.</p><p>The detection of these changes is remarkable, because linear trends have already been removed prior to analysis. Hence, their presence reflects intrinsic changes in the patterns of the time series. The metrics also allow for a detailed model evaluation from a nonlinear perspective.</p><p>An important methodological aspect is the temporal resolution of the time series. We investigate the scaling behavior of the nonlinear metrics through aggregation or decimation to coarser resolutions and conclude on what the scaling behavior may imply for inverse (hydrological) modelling tasks.</p>

scholarly journals Long-term spatiotemporal stability and dynamic changes in helminth infracommunities of bank voles (Myodes glareolus) in NE Poland

Parasitology ◽  
2015 ◽  
Vol 142 (14) ◽  
pp. 1722-1743 ◽  
Author(s):  
MACIEJ GRZYBEK ◽  
ANNA BAJER ◽  
MAŁGORZATA BEDNARSKA ◽  
MOHAMMED AL-SARRAF ◽  
JOLANTA BEHNKE-BOROWCZYK ◽  
...  
Keyword(s):  
Rank Order ◽  
Myodes Glareolus ◽  
Spatial Effects ◽  
Dynamic Changes ◽  
Ne Poland ◽  
Bank Voles ◽  
Temporal And Spatial ◽  
Host Evolution ◽  
Host Parasite

SUMMARYParasites are considered to be an important selective force in host evolution but ecological studies of host-parasite systems are usually short-term providing only snap-shots of what may be dynamic systems. We have conducted four surveys of helminths of bank voles at three ecologically similar woodland sites in NE Poland, spaced over a period of 11 years, to assess the relative importance of temporal and spatial effects on helminth infracommunities. Some measures of infracommunity structure maintained relative stability: the rank order of prevalence and abundance ofHeligmosomum mixtum, Heligmosomoides glareoliandMastophorus murischanged little between the four surveys. Other measures changed markedly: dynamic changes were evident inSyphacia petrusewicziwhich declined to local extinction, while the capillariidAonchotheca annulosafirst appeared in 2002 and then increased in prevalence and abundance over the remaining three surveys. Some species are therefore dynamic and both introductions and extinctions can be expected in ecological time. At higher taxonomic levels and for derived measures, year and host-age effects and their interactions with site are important. Our surveys emphasize that the site of capture is the major determinant of the species contributing to helminth community structure, providing some predictability in these systems.

scholarly journals Aerosol optical depth retrievals at the Izaña Atmospheric Observatory from 1941 to 2013 by using artificial neural networks

2016 ◽  
Vol 9 (1) ◽  
pp. 53-62 ◽  
Author(s):  
R. D. García ◽  
O. E. García ◽  
E. Cuevas ◽  
V. E. Cachorro ◽  
A. Barreto ◽  
...  
Keyword(s):  
Neural Networks ◽  
Time Series ◽  
Artificial Neural Networks ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Mineral Dust ◽  
Dust Particles ◽  
Filter Radiometer ◽  
Artificial Neural

Abstract. This paper presents the reconstruction of a 73-year time series of the aerosol optical depth (AOD) at 500 nm at the subtropical high-mountain Izaña Atmospheric Observatory (IZO) located in Tenerife (Canary Islands, Spain). For this purpose, we have combined AOD estimates from artificial neural networks (ANNs) from 1941 to 2001 and AOD measurements directly obtained with a Precision Filter Radiometer (PFR) between 2003 and 2013. The analysis is limited to summer months (July–August–September), when the largest aerosol load is observed at IZO (Saharan mineral dust particles). The ANN AOD time series has been comprehensively validated against coincident AOD measurements performed with a solar spectrometer Mark-I (1984–2009) and AERONET (AErosol RObotic NETwork) CIMEL photometers (2004–2009) at IZO, obtaining a rather good agreement on a daily basis: Pearson coefficient, R, of 0.97 between AERONET and ANN AOD, and 0.93 between Mark-I and ANN AOD estimates. In addition, we have analysed the long-term consistency between ANN AOD time series and long-term meteorological records identifying Saharan mineral dust events at IZO (synoptical observations and local wind records). Both analyses provide consistent results, with correlations  >  85 %. Therefore, we can conclude that the reconstructed AOD time series captures well the AOD variations and dust-laden Saharan air mass outbreaks on short-term and long-term timescales and, thus, it is suitable to be used in climate analysis.

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