Venice System Research Articles

Ecological Functions of Polychaetes Along Estuarine Gradients

Function in ecology can be understood as the role that each component plays in the surrounding environment. It can be studied through the functional traits of organisms and depends on variations of abundance in time and space. Nevertheless, traits should be clearly associated with functions. The functions performed by estuarine macrofauna along estuarine gradients and its variation in time are scarcely studied. We expected that the functional structure (i.e., the set of functions in a site) would not change significantly over estuarine gradients, even with changes in taxonomic composition, since different taxa may have similar traits, allowing the performance of the same functions. We used polychaete assemblages along three tropical estuaries sampled four different times, to test for differences in functional intensity between estuarine salinity zones (Venice system). From a literature search we selected the most frequent ecological functions performed by estuarine benthic assemblages and we explicitly established which polychaete functional traits, or combinations of traits, were directly related to these functions. Nutrient cycling, bioturbation and fragmentation of organic matter were the most frequent functions. We discovered that the last two were present throughout the entire salinity gradient (i.e., along different salinity zones) but with different intensities. The intensity of functions may also show significant variability in time. Nutrient cycling and fragmentation of organic matter showed strong variation among estuarine zones. Using traits explicitly associated with ecological functions is necessary to investigate function and function intensity. Future studies should investigate how precisely traits may alter specific environmental characteristics and ecosystem properties.

Cilamaya estuary zonation based on sea surface salinity with 2 Sentinel-2A satellite imagery

Estuaries act as transitional areas on the coastal zone that connect highly saline ocean environments with fresh river systems. This dynamic aquatic ecosystem is created by deep fluctuations in water quality and salinity levels. Cilamaya estuary supports a highly diverse marine ecosystem that is underutilized due to knowledge deficiencies of its variable rates of salinity. The aim of this study is to show the difference zone of estuary based on the sea surface salinity in the different time, so that Cilamaya Estuary areas can be utilized optimally for resource management. Sea surface salinity is obtained using algorithmic calculations based on the Sentinel-2A imagery. Salinity levels are studied based on the rainy and dry seasons. The higher salinity occur on the dry seasons, while on the rainy seasons have a lower salinity. Estuary areas experience 0.5-30 %o salinity placing it within the three zoning classes of the Venice System; Mexo-oligohaline; Mexo-mesohaline and Mexo-polyhaline.

The Influence Of Seasonality On Haline Zones In An Amazonian Estuary

Valentim, M.M.; Monteiro, S.M., and Rollnic, M., 2018. The influence of seasonality on haline zones in an Amazonian estuary. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 76–80. Coconut Creek (Florida), ISSN 0749-0208.This study relates salinity fluctuations throughout Mojuim estuary, dominated by macrotides and situated in the humid tropical region between the Para River mouth and the Atlantic ocean (−0.72° and −48.00°), Northeastern Para, Brazil. Water salinity in situ were measured, on the surface and at the bottom, with a multiparameter probe (Horiba U-50) for six months, corresponding to the intermediate season (July and August, 2016), dry season (November and December, 2016), and rainy season (January and February, 2017) during spring tide. Sampling stations comprehended 50 km throughout the estuary and were divided in five 10-km sectors. The sectors were classified according to the Venice System. Significant variations salinity (p>0.5) in water column were not observed, as it is a well-mixed estuary. During rainy season, were observed the lowest mean salinity (8.5±0.8 PSU), which increased to 15.99±0.37 PSU during the intermediate season, and to 22.38±0.61 PSU during dry season. Saline intrusion reached sector 5 (50 km upstream of the mouth) during dry season and was restricted to sector 3 (30 km) during rainy season. The latter showed the highest variation in haline zones in all seasons, and they varied from oligohaline during rainy season, to mesohaline during intermediate season, and polyhaline during dry season. During rainy and intermediate seasons, river domain limits tidal progression, and it is why sector 5 shows no haline variations, remaining as a freshwater zone, as opposed to dry season, when this sector shows a oligohaline zone, due to the higher tide reach and to the higher dispersion of salts in the estuary. These haline limits might vary interannually, which indicates the influence of climatological anomalies on estuary dynamics over the last years.

An evaluation of climate change effects in estuarine salinity patterns: Application to Ria de Aveiro shallow water system

It is of global interest, for the definition of effective adaptation strategies, to make an assessment of climate change impacts in coastal environments. In this study, the salinity patterns adjustments and the correspondent Venice System zonations adaptations are evaluated through numerical modelling for Ria de Aveiro, a mesotidal shallow water lagoon located in the Portuguese coast, for the end of the 21st century in a climate change context. A reference (equivalent to present conditions) and three future scenarios are defined and simulated, both for wet and dry conditions. The future scenarios are designed with the following changes to the reference: scenario 1) projected mean sea level (MSL) rise; scenario 2) projected river flow discharges; and scenario 3) projections for both MSL and river flow discharges. The projections imposed are: a MSL rise of 0.42 m; a freshwater flow reduction of ∼22% for the wet season and a reduction of ∼87% for the dry season. Modelling results are analyzed for different tidal ranges. Results indicate: a) a salinity upstream intrusion and a generalized salinity increase for sea level rise scenario, with higher significance in middle-to-upper lagoon zones; b) a maximum salinity increase of ∼12 in scenario 3 and wet conditions for Espinheiro channel, the one with higher freshwater contribution; c) an upstream displacement of the saline fronts occurring in wet conditions for all future scenarios, with stronger expression for scenario 3, of ∼2 km in Espinheiro channel; and d) a landward progression of the saltier physical zones established in the Venice System scheme. The adaptation of the ecosystem to the upstream relocation of physical zones may be blocked by human settlements and other artificial barriers surrounding the estuarine environment.

Assessment of a three-dimensional baroclinic circulation model of the Tagus estuary (Portugal)

Circulation patterns and physical regimes play a major role in estuarine ecosystems. Understanding how different drivers, like climate change, may affect the estuarine dynamics is thus fundamental to guarantee the preservation of the ecological and economical values of these areas. The Tagus estuary (Portugal) supports diverse uses and activities, some of which may be negatively affected by changes in the hydrodynamics and salinity dynamics. Numerical models have been widely used in this estuary to support its management. However, a detailed understanding of the three-dimensional estuarine circulation is still needed. In this study, a three-dimensional hydrodynamic baroclinic model was implemented and assessed using the modeling system SCHISM. The model assessment was performed for contrasting conditions in order to evaluate the robustness of the parametrization. Results show the ability of the model to represent the main salinity and water temperature patterns in the Tagus estuary, including the horizontal and vertical gradients under different environmental conditions and, in particular, river discharges. The model setup, in particular the vertical grid resolution and the advection scheme, affects the model ability to reproduce the vertical stratification. The TVD numerical scheme offers the best representation of the stratification under high river discharges. A classification of the Tagus estuary based on the Venice system regarding the salinity distribution for extreme river discharges indicates a significant upstream progression of the salt water during drought periods, which may affect some of the activities in the upper estuary (e.g., agriculture). The model developed herein will be used in further studies on the effects of climate change on the physical and ecological dynamics of the Tagus estuary.

Leaving the beaten track – Approaches beyond the Venice System to classify estuarine waters according to salinity

The Venice System is one of the best-known and most applied systems to classify waters with respect to salinity. It has often been subject to criticism because the criteria used to derive zone boundaries were not made explicit. Consequently, an alternative multivariate PCA method that aimed at identifying salinity zones by means of the salinity ranges preferred by species was introduced by Bulger et al. (1993). We tested the applicability of both methods using salinity and benthic macroinvertebrate data for the poikilohaline Elbe Estuary (Germany) from 1997 to 2012. This was done by comparing the resultant salinity zone limits from the two approaches with boundaries where significant community changes were found by means of cluster analysis. Only the Venice System polyhaline and limnetic zone boundaries, and the PCA method outer estuary zone limit, showed good agreement with the benthic community pattern. None of the other Venice System or PCA method zone limits reflected the benthic community patterns. Our findings suggest that zone limits can only be well determined from mean salinity at the inner and outer end of the estuary, where the variation of salinity is relatively low. In contrast, in the middle of the estuary variation in salinity is the better predictor of zone boundaries. Thus, application of the Venice System or the PCA method in poikilohaline estuaries, such as the Elbe, is not meaningful and their use should be limited to homoiohaline systems. For poikilohaline systems, we found cluster analysis to be a better tool to identify salinity-zone boundaries.

Kimmeridgian (Late Jurassic) ostracods from Highway A16 (NW Switzerland): taxonomy, stratigraphy, ecology, and biogeography

Ostracods are a common microfaunal element of the Kimmeridgian of the Jura Mountains in NW Switzerland. The stratigraphical subdivision within the Kimmeridgian can as clearly be inferred from ostracods as it is the case from the ammonite biozonation. This proves the utiliy of the ostracod biozonation, especially where ammonites are not available or rare. The ostracod-bearing layers of the sequence under study (middle part of the Reuchenette Formation = Banne Member, Courtedoux Member and Lower Virgula Marls) have been deposited in waters with highly brackish to marine salinities (high in the pliohaline range to—predominanttly—brachyhaline according to the Venice System, Oertli 1964). From the base of the section (base of the Banne Member, high brachyhaline in average), salinities slowly decreased, with lowest salinities in the lower dinosaur track levels of Courtedoux Member (high pliohaline on average). They then increased again to higher salinities (high brachyhaline on average) above the upper dinosaur track levels of the Courtedoux Member and the Lower Virgula Marls (lowermost A. eudoxus Zone). These trends perfectly correlate with the increased occurence of ammonites above the upper dinosaur track levels. In terms of Kimmeridgian ostracod palaeobiogeography, the fauna of the NW Swiss Jura Mountains described in this work is most similar to the Aquitan and Paris Basins, a little less to Northern Germany, and even less (with not even half of the species in common) to Southern Germany. The NW Swiss Jura Mountains still belong to a largely boreally influenced “Western and Central European subprovince”, whereas Southern Germany (though located more to the north) was subjected to an enhanced tethyan influence.

Adaptive Comanagement in the Venice Lagoon? An Analysis of Current Water and Environmental Management Practices and Prospects for Change

Adaptive comanagement (ACM) is often suggested as a way of handling the modern challenges of environmental governance, which include uncertainty and complexity. ACM is a novel combination of the learning dimension of adaptive management and the linkage dimension of comanagement. As has been suggested, there is a need for more insight on enabling policy environments for ACM success and failure. Picking up on this agenda we provide a case study of the world famous Venice lagoon in Italy. We address the following questions: first, to what extent are four institutional prescriptions typically associated with ACM currently practiced in the Venice system? Second, to what extent is learning taking place in the Venice system? Third, how is learning related to the implementation or nonimplementation of the prescriptions of ACM in the Venice system? Our analysis is based on interviews with stakeholders, participatory observation, and archive data. This paper demonstrates that the prescriptions of ACM are hardly followed in the Venice lagoon, but some levels of cognitive learning do take place, albeit very much within established management paradigms. Normative and relational learning are much rarer and when they do occur, they seem to have a relatively opportunistic reason. We propose that in particular the low levels of collaboration, because the governance system was deliberately set up in a hierarchical and mono-centric way, and the limited possibilities for stakeholder participation are implicated in this finding because they cause low levels of social capital and an incapacity to handle disagreements and uncertainty very well.

β-diversity as a measure of species turnover along the salinity gradient in the Baltic Sea, and its ­consistency with the Venice System

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 436:101-118 (2011) - DOI: https://doi.org/10.3354/meps09219 β-diversity as a measure of species turnover along the salinity gradient in the Baltic Sea, and its ­consistency with the Venice System S. Bleich1,*, M. Powilleit1, T. Seifert2, G. Graf1 1Institute of Biological Sciences-Marine Biology, University of Rostock, Albert Einstein Strasse 3, 18059 Rostock, Germany 2Leibniz Institute for Baltic Sea Research, Warnemünde, Seestrasse 15, 18119 Rostock, Germany *Email: steffen.bleich@googlemail.com ABSTRACT: Transition zones between marine and freshwater environments are characterized by a pronounced salinity gradient and concomitant variation in invertebrate species richness. Here we use the β-diversity concept to depict the species turnover of macrobenthic species along the salinity gradient of the Baltic Sea with salinities ranging from 34 in the transition zone to the North Sea to less than 5 in the Bothnian Sea. Based on 250 data sets from 72 locations that were grouped into 2 habitats defined according to their depths and sediment types (shallower: 15 to 19 m, fine to medium sand; deeper: 20 to 35 m, silt to silty sand), we calculated the ­Jaccard dissimilarity index (β1–J) as a measure of species turnover. To keep the focus on the salinity gradient, sediment characteristics and the time period covered by the data sets (spring and summer 1995 to 2005) were predefined. The mean hydrographic parameters, including temperatures, salinities and dissolved oxygen (DO) concentrations of the sample locations were derived from model ­calculations based on data gathered over a 3 yr period before sampling. At the deeper stations, the total number of macrofaunal species was 255, while at the shallower ones, 172 taxa were found. Statistical analyses revealed salinity to be the main structuring factor for macrobenthic species turnover. High correlations between the β1–J index and mean salinities in both habitats (Spearman’s rank correlation coefficient ρ = 0.88 in shallower and ρ = 0.86 in deeper areas) confirmed these findings. β-diversity values with median β1–J varied between 51 and 65% within the salinity classes eu-, poly-, α-meso- and β-mesohaline, while values of 75 to 100% characterized between-group comparisons. Furthermore, these high β-diversity values depict a discontinuous change in the communities and are found at salinities of around 10, 18, and 30, which ties in fairly well with the existing salinity boundaries postulated by the Venice System. KEY WORDS: Species turnover · β-diversity · Salinity gradient · Macrofauna · Venice System · Baltic Sea Full text in pdf format PreviousNextCite this article as: Bleich S, Powilleit M, Seifert T, Graf G (2011) β-diversity as a measure of species turnover along the salinity gradient in the Baltic Sea, and its ­consistency with the Venice System. Mar Ecol Prog Ser 436:101-118. https://doi.org/10.3354/meps09219 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 436. Online publication date: August 31, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

Using the salinity preferences of benthic macroinvertebrates to classify running waters in brackish marshes in Germany

Abstract Marshland streams along European coastlines are typically located in the transition zone from limnic to brackish conditions. They constitute a distinct and important stream type within the German stream typology, which is predominantly characterised by tidal influence and salinity. According to the Water Framework Directive (WFD) the basis for the abiotic classification of European transitional and coastal waters is the ‘Venice System’ (Weber, M., 2005. Ergebnisse der Bestandsaufnahme 2004 zur Umsetzung der europaischen Wasserrahmenrichtlinie (WRRL) in den Kustengewassern Mecklenburg-Vorpommerns. Rostocker Meeresbiol. Beitr. 14, 7–15). However, the extreme spatial and temporal variability in salinity and tidal influence determines and controls the macroinvertebrate communities of marshland river and stream ecosystems and hampers the application of the ‘Venice System’. Earlier, purely biotic classifications of brackish waters typically classify different brackish water zones, each with a specific macroinvertebrate community, and often yield unsatisfactory results due to the extensively dynamic abiotic factors found in marshland streams. In practice, the permanent impact of tidal charge means that stable salinity zones do not exist. This effect can than be intensified by freshwater discharges after heavy rainfall or high tides in combination with strong winds that hinder discharge into the open sea. To overcome the restricted applicability of abiotic and biotic classification systems, we present a scoring system for marshland streams that combines the abiotic salinity classes of the ‘Venice System’ with the salinity preferences of the macroinvertebrate community. This proposal is based on literature data for macroinvertebrate salinity tolerances and preferences. According to the 137 references that were evaluated, 151 macroinvertebrate taxa were classified into six salinity groups. In a second step, we applied this scoring scheme to empirical data from two official quality assessment surveys. These surveys had been carried out in ten estuary tributaries of German marshland areas in Lower Saxony and Schleswig-Holstein in order to implement the WFD. Applying the scoring system to these data revealed a clear (and expected) gradient that was not expressed in the abiotic data. Thus we conclude that the biotic salinity preferences of benthic macroinvertebrates are a useful baseline metric for the ecological assessment of marshland streams and other transitional waters. Regional revision and adaptation of taxonomic salinity preferences would broaden the applicability of this assessment to transitional waters worldwide.

Environmental factors affecting Phragmites australis litter decomposition in Mediterranean and Black Sea transitional waters

1. Leaf litter decomposition rates in aquatic ecosystems are known to be related to many abiotic and biotic factors. 2. Field experiments were carried out during spring 2005 in 16 ecosystems, each with four sampling sites, using the litter bag technique to investigate the influence of abiotic factors on patterns of reed litter breakdown in different physiographic, hydrological and physico-chemical gradients occurring in transitional water ecosystems in the Eastern Mediterranean and Black Sea. 3. Significant differences in leaf litter decomposition were observed among the studied ecosystems along univariate gradients of tidal range, water temperature, salinity and sinuosity index. 4. Overall, 71% of variance in the litter breakdown rate was explained by the hydrological, physico-chemical and physiographic components. Specifically, tidal range, salinity and sinuosity index are among the key factors in the most commonly used typological schemes for classifying transitional water ecosystems (i.e. Confinement Concept and Venice System), due to their influence on abundance and distribution of benthic macroinvertebrates and other guilds. 5. The patterns observed at the regional scale of the study suggest that certain key abiotic factors are likely to play a major role as drivers of plant detritus decomposition processes, through their influence on the overall metabolism of microorganisms and benthic macroinvertebrates. 6. These observations have implications for the identification of reference conditions for transitional water ecosystems in the studied area, on which all processes of classification and conservation of their ecological status are based.

Ecosystem processes: litter breakdown patterns in Mediterranean and Black Sea transitional waters

1 - Leaf litter decomposition rates, in aquatic ecosystems, are known to be related to many different abiotic and biotic factors. 2 - Here, we focus on the influence of abiotic factors, searching for patterns of reed litter decay rates on gradient of physiographic, hydrological and physico-chemical components of transitional water ecosystems. 3 - Field experiments were carried out in 16 water ecosystems in the Eastern Mediterranean and Black Sea in spring 2005. 4 - Significant differences of leaf litter decomposition were observed among ecosystems along univariate gradient of tidal range, index of sinuosity, water temperature and salinity. At least 71% of variance in the litter breakdown rate was explained by the considered abiotic factors. 5 - It is concluded that, at the macro-ecological scale of study, some key abiotic factors, such as tidal range and salinity, are suggested to play a major role as drivers of plant detritus decomposition processes. 6 - The relevance of the described abiotic drivers as descriptor of the most commonly used classification schemes for transitional water ecosystems (i.e., Confinement and Venice System classifications), is a further support to their role as environmental forcing factors.

Nekton community change along estuarine salinity gradients: Can salinity zones be defined?

Organisms tend to inhabit predictable portions of estuaries along salinity gradients between the ocean inlets (salinity > 35 psu) and the freshwater tributaries (salinity = 0). Previous studies have suggested that the continuous change in biological community structure along this gradient is relatively rapid at certain salinities. This is the basis for estuarine salinity zonation schemes similar to the classic Venice System (i.e., 0-0.5, 0.5-5, 5-18, 18-30, 30-40, > 40). An extensive database (n > 16,000 samples) of frequency of occurrence of nekton was used to assess evidence for estuarine salinity zones in two southwest Florida estuaries: Tampa Bay and Charlotte Harbor. Rapid change in nekton community structure occurred at each end of the estuarine salinity gradient, with comparatively slow (but steady) change in between. There was little strong evidence for estuarine salinity zones at anything other than low salinities (0.1-1). As previously suggested by other authors, estuaries may be regarded as ecoclines, because they form areas of relatively slow but progressive ecological change. The ends of the estuarine salinity gradient appear to be ecotones (areas of rapid change) at the interfaces with adjacent freshwater and marine habitats. This study highlights the rapid change that occurs in nekton community structure at low salinities, which is of relevance to those managing freshwater inflow to estuaries.

Biologically-Based Estuarine Salinity Zones Derived from a Multivariate Analysis

Principal Component Analysis (PCA) was used to derive estuarine salinity zones based on field data on the salinity ranges of 316 species/life stages in the mid-Atlantic region (chiefly Chesapeake Bay and Delaware Bay species). Application of PCA to the data matrix showed that the structure underlying a diversity of salinity distributions could be represented by only five Principal Components corresponding to five overlapping salinity zones: freshwater to 4‰, 2–14‰, 11–18‰, 16–27‰ to marine. The derived salinity zonation showed both differences and similarities to the Venice System of estuarine zonation. However, unlike the static and essentially descriptive Venice System, the new method will allow researchers to establish biologically-relevant local salinity zones, and then develop hypotheses about the processes that give rise to the resulting patterns. Examples of this procedure are given for the mid-Atlantic region. The method used here may also be useful for studying distributions across other environmental gradients, such as temperature, pH, substrate, turbidity, vegetation, or latitude.

Classification of brackish coastal inland waters

1. The fauna of nineteen brackish coastal inland waters in the southwestern part of the Netherlands has been investigated by cluster analysis. Several clusters were recognized and these showed a correlation with the average chlorinity together with the fluctuations in chlorinity. 2. A classification system of the brackish waters is given. This system shows some similarities with the “Venice system”. 3. It appears that marine species have less resistance against incidentally low chlorinities than brackish-water species. 4. Marine species have a lower degree of resistance against regular fluctuations in chlorinity than brackish-water species.

The Venice system for the classification of marine waters according to salinity : Symposium on the classification of brackish waters, Venice, 8-14 April 1958

The Venice system for the classification of marine waters according to salinity : Symposium on the classification of brackish waters, Venice, 8-14 April 1958

The Venice System for the Classification of Marine Waters According to Salinity

Limnology and OceanographyVolume 3, Issue 3 p. 346-347 Notes and CommentFree Access The Venice System for the Classification of Marine Waters According to Salinity First published: July 1958 https://doi.org/10.4319/lo.1958.3.3.0346Citations: 54AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume3, Issue3July 1958Pages 346-347 RelatedInformation