The Mondego estuary is a well-described system located on the North Atlantic Ocean, where cultural eutrophication progressed over the last decades of the 20th century. Consequently, and due to a large productivity of Ulva spp., Zostera noltii meadows were severely reduced with a concomitant decrease in environmental quality. In 1998, experimental mitigation measures were implemented, via changes in hydrology to increase circulation and diversion of nutrient-rich freshwater inflow, to reverse the process in the most affected area of the estuary - its South arm.; http://www.sciencedirect.com/science/article/B6WDV-4R5F08P-1/1/178ea3ee141e5cbe0ae832f88308a00a
The Mondego estuary is a well-described polyhaline type of transitional water located at the North Atlantic Ocean Ecoregion, where cultural eutrophication progressed over the last decades of the 20th century. Consequently, and due to huge productivity of Ulva spp. Zostera noltii meadows were severely reduced causing the whole ecosystem to become impoverished in terms of macrofaunal abundance, biomass and species richness with a concomitant lowering of secondary production. In 1998, experimental mitigation measures were implemented, via changes in hydrology to increase circulation and diversion of nutrient rich freshwater inflow, to reverse the process in the most affected area of the estuary - its south arm. Thus, the system quality status was assessed before and after 1998, over a ten year period. The OSPAR comprehensive procedure, the first phase of the US-NEEA procedure and the proposed EU-WFD physicochemical status criteria were applied to the data before and after the modifications and all show that the system health has improved. Nonetheless, the annual means of the oxidised forms of nitrogen and of phosphate were not reduced. In fact, applying criteria used in classifying the nutrient levels in transitional waters and the Baltic sea trophic condition...
From 1980 to 2000, the Mondego estuary (Portugal) suffered dramatic changes due to eutrophication, leading to a decline in seagrass beds and changes in community structure, namely a decline in species richness and replacement of herbivores by detritivores. Because the conservation status of the estuary was being compromised, a restoration project was implemented in 1998 in order to restore the original natural seagrass habitat. This project included several restoration/management measures, including the protection of the remaining seagrass patches and improvement of the hydraulic conditions through modifying sluice opening regimes, thereby reducing the nutrient loading in the southern arm of the estuary. In addition, several stakeholder forums were convened to inform local people of the ecological and economic importance of the area. In this paper we evaluate the success of this management plan as judged by changes in the polychaete assemblages.; http://www.sciencedirect.com/science/article/B6WDV-4KW5WMJ-2/1/bb4d7ae09864d325f549e5b779b3f582
Over the last 20 years, loss of seagrass beds, often related with increased eutrophication, became a common problem worldwide. In the Mondego estuary (Portugal), eutrophication has triggered serious biological changes, which led to an overall increase in primary production and to a progressive replacement of seagrass Zostera noltii beds by coarser sediments and opportunistic macroalgae.; http://www.sciencedirect.com/science/article/B6T8F-4B76GY1-1/1/2f9baf58e9f5bc8689beab357620d6a8
Increasingly, management agencies require that the remediation of eutrophic waters be addressed at the level of the whole ecosystem. One whole-system approach to quantify ecosystems is called ecological network analysis. Ascendency theory, the branch of the field that deals with the quantification of whole-system status, specifically addresses the definition of eutrophication. This definition has been applied to data taken over a gradient of eutrophication. Three separate areas were observed: a non-eutrophic area (with Zostera noltii meadows), an intermediate eutrophic area (Z. noltii absent and macroalgae abundant at times) and a strongly eutrophic area (where Enteromorpha spp. blooms occur with regularity). Pulse eutrophication was considered as the major driving force behind a gradual shift in primary producers from a community dominated by rooted macrophytes (Z. noltii) to a community dominated by green macroalgae. The measures associated with the intermediate eutrophic region turned out not to be intermediate to those at the gradient extremes. The most likely explanation appears to be the highly unstable nature of this area. Conditions along the spatial gradient are discussed as representing various stages in the temporal evolution of the system...
Eutrophication in the Mondego estuary gave rise to qualitative changes in the benthic community, involving the replacement of
eelgrass, Zostera noltii, by green algae such as Enteromorpha spp. and Ulva sp. It seems reasonable to assume that, through time, such changes
may determine a selected new trophic structure. Hydrobia ulvae, a dominant species in terms of abundance and biomass, was studied with regard
to life history, population dynamics and productivity in relation to changing environmental conditions along the eutrophication gradient. The
purpose was to examine to what extent this species may adapt to the new emergent conditions. During the study period, H. ulvae population
exhibited both temporal and spatial density variations. The settlement pattern did not change along the eutrophication gradient, and took place
in March, June, July and September. However, the population was denser in the less eutrophied areas, corresponding to Z. noltii meadows, when
compared to the eutrophied ones, where Enteromorpha spp. blooms are usually observed. Growth was continuous through life but growth rates
were higher during spring, decreased from early summer to mid fall and practically ceased during winter, and then gradually increased again
up to spring. Life span was estimated as 21 ± 3 months. Growth productivity (P) was estimated as 93.7 g AFDW?m–2?year–1 in the Z. noltii
The life cycle, population dynamics and production of Ampithoe valida was studied from an intertidal mudflat in central Portugal, close to the northern limit of the species¹ distributional range in the eastern Atlantic Ocean. Sampling was carried out in eutrophicated areas, where macroalgae blooms of Enteromorpha spp. occur usually from January to early summer, and also in non-eutrophicated areas, with Zostera noltii meadows. A. valida showed a contagious distribution and the population density clearly changed during the study period along the eutrophication gradient. No migratory patterns were detected between the estuary and the sea, but migrations inside the estuary might have occurred. Females were morphologically recognisable at smaller sizes than males. Females reached sexual maturity before males, but males may live slightly longer than females. Females are iteroparous, producing 2, perhaps 3, broods. A 2-generation life cycle involving a short-lived (7 mo), fast-growing summer generation and a longer-lived (9 mo), slower-growing generation that overwinters is hypothesised. Ovigerous females were present year-round. Eggs, depending on the season, increase differently in volume during marsupial development. No correlations were found between fecundity (number of eggs) and the size of females. Along the eutrophication gradient no differences were found regarding the biology of the species. Besides these features...
The south arm of Mondego estuary, located in the central western Atlantic coast of Portugal, is almost silted
up in the upstream area. So, the water circulation is mostly driven by tides and the tributary river Pranto
discharges. Eutrophication has been taking place in this ecosystem during last twelve years, where
macroalgae reach a luxuriant development covering a significant area of the intertidal muddy flat.
A sampling program was carried out from June 1993 to June 1994. Available data on salinity profiles and on
nutrients loading into the estuary south arm are being used in order to get a better understanding of the
ongoing changes. River Pranto flow discharges, controlled by a sluice, were also monitored.
Integral formulations are typically based on assumptions of steady-state and well mixed systems and thus
cannot take into account the space and time variability of estuarine residence times, due to river discharge
flow, tidal coefficients, discharge(s) location and time of release during the tidal cycle. This work presents
the hydrodynamics modelling (2D-H) of this system in order to estimate the residence times variability and
to assess their effect on the estuarine eutrophication vulnerability, contributing for proper environmental
management strategies selection
Benthic eutrophication often gives origin to qualitative changes in marine and estuarine ecosystems, for example
the shift in primary producers, often followed by changes in species composition and trophic structure at other levels.
Through time such modifications may determine a selected new trophic structure. The development of structural
dynamic models will allow to simulate such changes, using goal functions to guide ecosystem behaviour and
development. The selection of other species and other food web may then be accounted by a continuous optimisation
of model parameters according to an ecological goal function. Exergy has been applied in structural dynamic models
of shallow lakes, and appears to be one of the most promising approaches. Theoretically, exergy is assumed to
become optimised during ecosystems development, and ecosystems are supposed to self organise towards a state of
an optimal configuration of this property. Exergy may then constitute not only a suitable system-oriented character-
istic to express natural tendencies of ecosystems evolution, but also a good ecological indicator of ecosystems health.
Biodiversity is also an important characteristic of ecosystems structure, constituting a powerful and traditional
We studied the eutrophication history of a tropical shallow reservoir in the So Paulo metropolitan region, southeast Brazil. We analyzed grain size, geochemistry, diatom assemblages, and land-use records in a sediment core from the reservoir to infer its trophic state history during the last similar to 110 years (1894-2005). Eighty diatom species were observed in the core and shifts in the relative abundances of planktonic and benthic taxa indicate major limnological changes associated with complex interactions between hydrologic factors and eutrophication. Discostella stelligera was associated with deforestation and water physical changes whereas Aulacoseira granulata, a species abundant throughout the core, was mostly associated with high flux conditions and erosion events, regardless of trophic state. Eutrophication was triggered by construction of the city zoo (1958) and installation of the So Paulo State Department of Agriculture (1975) within the Gar double dagger as watershed, and increasing loads of untreated sewage from these institutions. The data suggest that deterioration in water quality began after similar to 1975 and markedly accelerated after similar to 1990. The reservoir has been hypereutrophic since 1999. Steady increases in geochemical proxies for trophic state...
O objetivo do presente estudo foi investigar como o grau de trofia dos reservatórios interfere na transferência trófica de ácidos graxos (FA) aos peixes teleósteos de hábitos alimentares distintos, relacionando os principais FAs considerados biomarcadores à sua importância em processos bioquímicos. Para isso, fêmeas adultas de Astyanax fasciatus, uma espécie onívora, e Hoplias malabaricus, uma espécie carnívora, foram amostradas durante um ano em dois reservatórios com diferentes graus de trofia na região metropolitana de São Paulo: Ponte Nova, considerado o reservatório referência, e o braço Taquacetuba no reservatório Billings, local hipereutrófico. O perfil de FAs do séston, conteúdo estomacal e dos triacilgliceróis (Tg) e fosfolipídios (Fl) teciduais foram analisados por cromatografia gasosa. Como um reflexo do perfil de FAs do séston, juntamente com o conteúdo estomacal, foi possível observar um predomínio de ácidos graxos polinsaturados (PUFAs) n6, como C18:2n6 e ARA (ácido araquidônico), e do FA C18:1n9 na maioria dos tecidos analisados das fêmeas de A. fasciatus no reservatório referência, enquanto houve maior porcentagem de HUFAs (ácidos graxos altamente insaturados) n3, principalmente EPA (ácido eicosapentaenoico) e DHA (ácido docosahexaenoico) nos tecidos das fêmeas coletadas no reservatório hipereutrófico...
River Cavado water quality variability was studied for eutrophication vulnerability assessment at a new
surface water supply intake. Since the river flow regime is artificially controlled by upstream multipurpose
reservoirs, mathematical modelling was applied in evaluating alternative management scenarios. Due to the
fact that surface water quality at intake location is mainly affected by a 5 km upstream wastewater treatment
plant effluent discharge, algae and nutrients concentration simulations have been worked out in order to
identify critical situations. Different algal concentration profiles along the river were obtained for local
conditions of light energy, water temperature and estimated nutrient loads, showing high probability of
eutrophication occurrence for some of the simulated scenarios. The discussion of results of this study
appears to be very useful for river basin wide water management policies evaluation.
The south arm of Mondego estuary, located in the central western Atlantic coast of Portugal, is almost silted up in the upstream area. So, the water circulation is mostly driven by tides and the tributary river Pranto discharges. Eutrophication has been taking place in this ecosystem during last twelve years, where macroalgae reach a luxuriant development covering a significant area of the intertidal muddy flat.
A sampling program was carried out from June 1993 to June 1994. Available data on salinity profiles and on nutrients loading into the estuary south arm are being used in order to get a better understanding of the ongoing changes. River Pranto flow discharges, controlled by a sluice, were also monitored.
Integral formulations are typically based on assumptions of steady-state and well mixed systems and thus cannot take into account the space and time variability of estuarine residence times, due to river discharge flow, tidal coefficients, discharge(s) location and time of release during the tidal cycle. This work presents the hydrodynamics modelling (2D-H) of this system in order to estimate the residence times variability and to assess their effect on the estuarine eutrophication vulnerability, contributing for proper environmental management strategies selection.
River Cavado water quality variability was studied for eutrophication vulnerability assessment at a new surface water supply intake. Since the river flow regime is artificially controlled by upstream multipurpose reservoirs, mathematical modelling was applied in evaluating alternative management scenarios. Due to the fact that surface water quality at intake location is mainly affected by a 5 km upstream wastewater treatment plant effluent discharge, algae and nutrients concentration simulations have been worked out in order to identify critical situations. Different algal concentration profiles along the river were obtained for local conditions of light energy, water temperature and estimated nutrient loads, showing high probability of eutrophication occurrence for some of the simulated scenarios. Results discussion of this study appears to be very useful for river basin wide water management policies evaluation.
Estuaries and coastal lagoons are commonly subjected to intensive anthropogenic stress due to massive pollutant loading from urbanised riparian areas. Nutrient enrichment is a key-factor for habitat degradation, leading to sensible structural changes in estuarine ecosystems with the consequent occurrence of eutrophication processes. The influence of hydrodynamics must not be neglected on estuarine eutrophication vulnerability assessment. In fact, flushing time affects the transport and the permanence of water and its constituents inside an estuary, so the increase of estuarine flushing capacity can be seen as a management measure to mitigate or to invert eutrophication processes, like the one observed in the Mondego River estuary
(Portugal), during the last two decades.
In this work, an integrated 2-DH water quality model was applied to calculate water residence time values, at different simulated management scenarios of the Mondego estuary. The results of the performed simulations illustrate the strong assymmetry of flood and ebb duration time at the inner sections of this estuary, a keyparameter
for a correct tidal flow estimation, as the major driving force of the southern arm flushing capacity, as well as a spatial and temporal variability of calculated RT values.
The conclusions of this work confirm the crucial influence of hydrodynamics on estuarine water quality status and the usefulness of this hydroinformatic tool as contribution to support the design of a sustainable management plan...
There is an ongoing eutrophication process in the Ria de Aveiro coastal lagoon (Portugal), with progressive replacement of rooted primary producers for macroalgae. Taking advantage of a well-defined environmental contamination gradient, we studied mercury accumulation and distribution in the aboveground and the belowground biomass of several salt marsh plants, including the seagrass species Zostera noltii and the dominant green macroalgal species Enteromorpha sp. The results of these experiments were then placed into the context of the estuarine mercury cycle and transport from the contaminated area.
All salt marsh plants accumulated mercury in the root system, with Halimione portulacoides showing the highest levels, with up to 1.3 mg kg?1 observed in the most contaminated area. Belowground/aboveground ratios were generally below 0.4, suggesting that salt marsh plants are efficient immobilizers and retainers of mercury agents. Moreover, due to their sediment accretion capacities, salt marsh plants seem to play an important role in the sequestration of mercury in estuarine sediments.
Seagrasses, on the other hand, accumulated considerable amounts of mercury in the aboveground biomass with belowground/aboveground ratios reaching as high as 1.4. These results may be due to their different routes of uptake (roots and foliar uptake) which suggests that seagrass meadows can be an important agent in the export of mercury from contaminated areas...
Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em
Engenharia do Ambiente, perfil Engenharia Sanitária; Coastal eutrophication is a global problem which affects many natural systems and
human activities throughout the world. The phenomenon of eutrophication has increased
substantially due to human activities. It is caused by excess nutrients and is identified by the emergence of some symptoms. The proposed assessment will address this problem in a more specific way. The Assessment of Estuarine Trophic Status (ASSETS)methodology is going to be performed to two Northern Irish Loughs in order to rank their
eutrophication status and allow a comparison with other existing methods. The data
available for these systems allowed the implementation of this innovative methodology, which can provide a classification based on pressure, state and response. Thus, by considering the influences of anthropogenic activities over the coastal areas, examination of specific symptoms of the water systems and analyzing the indicators for future response, it is possible to achieve consistent results regarding the quality of the water in
the “loughs” and, consequently...
This is a long-term study (1993-1998) on the effects of increasing eutrophication on the crustacean zooplankton structure in a eutrophic reservoir. The study first demonstrates that the eutrophication increase verified is a phenomenon well described by a single abiotic variable: total phosphorus. During the study period, zooplankton suffered extensive qualitative and quantitative changes. Significant size and biomass responses of certain zooplankton groups to the temporal variations of total phosphorus were found. These findings suggest that the variables size and biomass of major zooplankton groups should always be considered simultaneously in order to assess impacts caused by eutrophication on the structure of zooplankton.
AIM: Investigate spatial and temporal variation in the aquatic macrophyte community in four urban reservoirs located in Curitiba metropolitan region, Brazil. We tested the hypothesis that aquatic macrophyte community differ among reservoirs with different degrees of eutrophication. METHODS: The reservoirs selected ranged from oligotrophic/mesotrophic to eutrophic. Sampling occurred in October 2011, January 2012 and June 2012. Twelve aquatic macrophytes stands were sampled at each reservoir. Species were identified and the relative abundance of aquatic macrophytes was estimated. Differences among reservoirs and over sampling periods were analyzed: i) through two?way ANOVAs considering the stand extent (m) and the stand biodiversity - species richness, evenness, Shannon-Wiener index and beta diversity (species variation along the aquatic macrophyte stand); and ii) through PERMANOVA considering species composition. Indicator species that were characteristic for each reservoir were also identified. RESULTS: The aquatic macrophyte stand extent varied among reservoirs and over sampling periods. Species richness showed only temporal variation. On the other hand, evenness and Shannon-Wiener index varied only among reservoirs. The beta diversity of macrophyte stands did not vary among reservoirs or over time...
AIM: This research aimed to study the composition of epilithic diatom flora in headwater areas of the sub-basin of the Andreas stream, RS, Brazil, and their relation with eutrophication processes. METHODS: Quarterly excursions (March, June, September, December 2012 and Mach 2013) were performed in ten sampling points selected in the sub-basin, to collect samples for the identification and counting the organisms in the group of diatoms (Class Bacillariophyceae). RESULTS: The results indicated the occurrence of 243 taxa, distributed in 53 genera. Of these, 59 were considered abundant, being distributed in 29 genera. Seven species showed elevated tolerance levels to organic pollution and eutrophication: Adlafia drouetiana (R. M. Patrick) Metzeltin & Lange-Bertalot, Amphipleura lindheimeri Grunow; Fallacia monoculata (Hustedt) D. G. Mann, Navicula cryptotenella Lange-Bertalot, Navicula symmetrica R. M. Patrick, Nitzschia palea (Kützing) W. Smith and Sellaphora auldreekie D. G. Mann & S. M. McDonald in Mann et al. CONCLUSION: Although this research has been conducted in headwater areas, the occurrence of these seven species could be explained by considering the use of these areas for agricultural and livestock purposes, compromising the stability of these aquatic ecosystems...