Description of the three shallow estuaries: Mondego River (Portugal), Roskilde Fjord (Denmark) and the Lagoon of Venice (Italy)

Flindt, Mogens; Kamp‐Nielsen, Lars; Marques, João Carlos; Pardal, Miguel Ângelo; Bocci, Martina; Bendoricchio, G.; Salomonsen, Jørgen; Nielsen, Søren Nors; Jørgensen, Sven Erik

doi:10.1016/s0304-3800(97)00092-6

Cited by 116 publications

(106 citation statements)

References 8 publications

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“…RF is a shallow (3-m mean depth), semi-enclosed and nutrient-rich estuary of 122 km 2 , which receives high-nutrient loads from its 1127 km 2 drainage area (Flindt et al, 1997). The GB is part of the 37 333 km 2 Kattegat and Belt Sea area (17-m mean depth), and is the main connection between the Baltic Sea and the North Sea and is therefore almost permanently stratified (Jørgensen et al, 2013).…”

Section: Sampling and Environmental Parametersmentioning

confidence: 99%

Significant N2 fixation by heterotrophs, photoheterotrophs and heterocystous cyanobacteria in two temperate estuaries

et al. 2014

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Nitrogen (N) fixation is fueling planktonic production in a multitude of aquatic environments. In meso-and poly-haline estuaries, however, the contribution of N by pelagic N 2 fixation is believed to be insignificant due to the high input of N from land and the presumed absence of active N 2 -fixing organisms. Here we report N 2 fixation rates, nifH gene composition and nifH gene transcript abundance for key diazotrophic groups over 1 year in two contrasting, temperate, estuarine systems: Roskilde Fjord (RF) and the Great Belt (GB) strait. Annual pelagic N 2 fixation rates averaged 17 and 61 mmol N m À 2 per year at the two sites, respectively. In RF, N 2 fixation was mainly accompanied by transcripts related to heterotrophic (for example, Pseudomonas sp.) and photoheterotrophic bacteria (for example, unicellular diazotrophic cyanobacteria group A). In the GB, the first of two N 2 fixation peaks coincided with a similar nifH-expressing community as in RF, whereas the second peak was synchronous with increased nifH expression by an array of diazotrophs, including heterotrophic organisms as well as the heterocystous cyanobacterium Anabaena. Thus, we show for the first time that significant planktonic N 2 fixation takes place in mesohaline, temperate estuaries and that the importance of heterotrophic, photoheterotrophic and photosynthetic diazotrophs is clearly variable in space and time.

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Section: Sampling and Environmental Parametersmentioning

confidence: 99%

Significant N2 fixation by heterotrophs, photoheterotrophs and heterocystous cyanobacteria in two temperate estuaries

et al. 2014

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“…Macroalgal blooms of Ulva spp. have regularly been observed in the Mondego over the last 20 years (Flindt et al, 1997;Marques et al, 1997Marques et al, , 2003Lillebø et al, 1999;Pardal et al, 2000Pardal et al, , 2004Martins et al, 2001;Dolbeth et al, 2003;Cardoso et al, 2004). Nevertheless, such macroalgal blooms may not occur in exceptionally rainy years.…”

Section: Study Areamentioning

confidence: 99%

Mass balanced models of the food web in three areas along a gradient of eutrophication symptoms in the south arm of the Mondego estuary (Portugal)

Patrício

Marques

2006

Ecological Modelling

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EutrophicationTrophic structure a b s t r a c t Three Ecopath with Ecosim models were constructed to represent the eutrophication gradient along the south arm of the Mondego estuary (Portugal). Sampling was conducted in three areas representative of different environmental situations along the gradient: (a) a non-eutrophic area (Zostera noltii meadows), (b) an intermediate eutrophic area (macrophyte absent, although residual roots can still be found in the sediment, and the occasional formation of abundant macroalgae mats) and (c) a strongly eutrophic area (macrophyte community totally absent for at least a decade and strong, regularly occurring, blooms of Ulva spp.). Field, laboratory and literature information were used to construct the models, as well as empirical ecological knowledge gained from years of work on this system. Approximately 76 trophic groups (e.g. Phytoplankton and Zooplankton species), species and genera were included. These species were grouped into 43, 36 and 34 model groups for Zostera sp. meadows, intermediate eutrophic area and strongly eutrophic area, respectively. The groups were arranged by trophic similarity and habitat preferences; special distinction is given to macrofauna. Biomass, production, consumption, and diet are among the parameters used to describe each group. The sum of consumptions, exports, respiration, production, flow to detritus, total system throughput and annual rate of net primary production was always higher in the Zostera sp. meadows, followed by the strongly eutrophic area and, finally, by the intermediate eutrophic area.

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“…In addition, this estuary supports several industries, many salt-works and aquaculture farms, and also receives the nutrient and chemical discharge from agricultural areas of the lower Mondego river valley. As a whole, the estuary is under severe environmental stress, namely an ongoing eutrophication process [18,26,29,30,32,39,40,41].…”

Section: Introductionmentioning

confidence: 99%

Population structure, dynamics and production of Hydrobia ulvae (Pennant) (Mollusca: Prosobranchia) along an eutrophication gradient in the Mondego estuary (Portugal)

1999

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-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 ⋅year -1 in the strongly eutrophied area. The average annual biomass (B √ ) (standing stock) of the population was estimated as 70.2 g AFDW⋅m -2 in the Z. noltii meadows, 5.5 g AFDW⋅m -2 in the eutrophied area, and 7.4 g AFDW⋅m -2 in the strongly eutrophied area. P/B √ and E/B √ ratios were estimated as 1.3 and 4.8 in the Z. noltii meadows, 2.8 and 9.5 in the eutrophied area, and 4.5 and 13.2 in the strongly eutrophied area, respectively. As a pattern, the standing stock decreased as a function of increasing eutrophication, while P/B √ and E/B √ ratios increased following the same gradient. There is evidence that H. ulvae population structure and annual production are seriously affected by eutrophication, namely by macroalgal bloom dynamics. Moreover, results suggest that H. ulvae might be suffering a change in its adaptive strategy along the eutrophication gradient, becoming closer to a typical 'r' strategist in the strongly eutrophied areas. © 1999 Éditions scientifiques et médicales Elsevier SAS Eutrophication / Hydrobia ulvae / life cycle / population dynamics / productivity

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Description of the three shallow estuaries: Mondego River (Portugal), Roskilde Fjord (Denmark) and the Lagoon of Venice (Italy)

Cited by 116 publications

References 8 publications

Significant N2 fixation by heterotrophs, photoheterotrophs and heterocystous cyanobacteria in two temperate estuaries

Significant N2 fixation by heterotrophs, photoheterotrophs and heterocystous cyanobacteria in two temperate estuaries

Mass balanced models of the food web in three areas along a gradient of eutrophication symptoms in the south arm of the Mondego estuary (Portugal)

Population structure, dynamics and production of Hydrobia ulvae (Pennant) (Mollusca: Prosobranchia) along an eutrophication gradient in the Mondego estuary (Portugal)

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