Characterization of ammonia-assimilating bacteria in a lagoon for wastewater from a paddock of dairy cattle

We investigated microorganisms that assimilated ammonia in lagoon treatment processes. Ammonia‐assimilating microorganisms were detected by nitrogen‐limited medium that contained ammonia as the sole nitrogen source. Numbers of ammonia‐assimilating aerobes (log CFU/g) were 3.4, 4.8, 5.0, 4.8 and 5.0 (log CFU/mL) on the culture plate incubated at 4°C, 10°C, 15°C, 20°C and 25°C, respectively. Many isolates used ammonia in high rates when they were purely cultivated in nitrogen‐limited medium added to sterilized lagoon extract. Many of them used ammonia even when they were cultivated in media containing viable microbial flora of the lagoon. Among them, enterobacteriaceae and Pseudomonas sp. were identified by analysis of 16S ribosomal DNA.     

Factors influencing migration of Penaeus indicus in the Negombo lagoon on the west coast of Sri Lanka

Juveniles of Penaeus indicus (Milne Edwards) occur in the Negombo lagoon Sri Lanka and on maturing they return to the sea for reproduction. Cohort analysis indicated pulses of immigration to the nursery areas in February and June. The growth rates for juveniles were relatively high compared with that of adults. Three groups of prawns were identified in the lagoon: `small quick movers', `larger long stay individuals' and an `intermediate group'. There were few identifiable emigration pulses from the lagoon towards the offshore areas. It appears that osmotic stress caused by low salinity waters in the lagoon during the periods of high precipitation may be the strongest influence triggering the onset of emigration.     

Population density estimation of southern stingrays Dasyatis americana on a Caribbean atoll using distance sampling

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Could European marine conservation policy benefit from systematic conservation planning?

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Effects of iron-ore mining and processing on metal bioavailability in a tropical coastal lagoon

Background, aim, and scope

In water systems, water quality and geochemical properties of sediments determine the speciation of trace metals, metal transport, and sediment–water exchange, influencing metal availability and its potential effects on biota. Studies from temperate climates have shown that iron-ore mining and tailing wastewaters, besides being a source of trace metals, usually show high levels of dissolved ions and particulate suspended matter, thus having the potential of indirectly changing metal bioavailability. For the first time in the tropics, we identified the effects of iron-ore mining and processing on metal bioavailability in a coastal lagoon. With an extensive sampling scheme, we investigated the potential sources of metals; the links among metal levels in water, sediments, and invertebrates; and the contrasting effects on metal speciation and bioavailability.

Methodology

The metals Fe, Mn, Al, Cr, Zn, Cu, Ni, Pb, Cd, Hg, and As were measured in water, sediments (surface and profiles), and invertebrates from Mãe-Bá Lagoon and in the sites directly influenced by the mining operations (tailing dams and nearby rivers). In addition, samples from two other lagoons, considered pristine, were analyzed. The study area is located in the southeast of Brazil (Iron Quadrangle Region and a coastal area of Espírito Santo State). General water characteristics included pH, dissolved organic carbon, alkalinity, and anion composition. Water metal speciation was assessed by a speciation model (Chemical Equilibria in Aquatic Systems). Grain-size distribution, organic carbon, carbonate, and acid volatile sulfide (AVS) were determined in sediments. Statistical methods included comparison of means by Mann–Whitney test, ordination and correlation analyses, and analysis of regression for geochemical normalization of metals with grain size.

Results and discussion

The dissolved metal concentrations, the total metal levels in sediments, and the normalization based on the fine sediment fraction showed that the mining operations constitute potential sources of Fe, Mn, Cr, Cu, Ni, Pb, As, and Hg to Mãe-Bá Lagoon. However, trace metal availability was reduced because of increased pH, hardness, and sulfide content (356 μmol/g) in the sites influenced by the mining. The lagoon showed similar water chemistry as in the mining sites, with metal bioavailability further decreased by the presence of dissolved organic carbon and chloride. Although AVS levels in the lagoon were low (0.48–56 μmol/g), metal bioavailability was reduced because of the presence of organic matter. Metal levels in invertebrates confirmed the predicted low metal bioavailability in Mãe-Bá Lagoon. The lagoon was considered moderately contaminated only by Hg and As.

Conclusions

The iron-ore mining and processing studied here constitute potential sources of metal pollution into the tropical lagoon. Contrary to expectations, however, it also contributes to reducing the overall metal bioavailability in the lagoon.

Recommendations and perspectives

These findings are believed to be useful for evaluating metal exposure in a more integrated way, identifying not only the sources of pollution but also how they can affect the components involved in metal speciation and bioavailability in water systems, leading to new insights.     

Gonadosomatic index and gonad histopathology of Gobius niger (Gobiidea, Teleost) from Bizerta lagoon (Tunisia): Evidence of reproduction disturbance

To evaluate the effect of anthropogenic pollution on fish reproduction in Bizerta lagoon, one of the largest Tunisian lagoons subjected to various anthropogenic and industrial pressures, the gonadosomatic index (GSI) and gonad histology of mature black goby (Gobius niger) were studied. Fish were collected during the breeding seasons from six stations differently impacted and in one reference station located at the seaward entrance of Ghar el Melh (GH) lagoon. In both sexes, we detected the presence of an overall weaker GSI in Bizerta lagoon than in control fish. These GSI alterations were accompanied by histopathological changes. In females, no significant differences in oocyte size were found across all the sample sites. However, a higher incidence of oocyte lesions (atretic oocytes, cytoplasmic retraction and karyoplasmic cluping) was found in stations located near agricultural activity zones. Histological observation of the testes revealed, as well, abnormalities in Bizerta lagoon fish: germ cells syncytium, vacuolated germ cells, melano-macrophage center and increase of gaps in the interstitium between lobules were detected with a high prevalence in stations influenced by industrial and/or urban activities. In addition, association between gonad fish histopathology and the presence of organic pollutants (DTT, PAHs and organotins) in sediment was noted. These results suggest that the chemical pollution in this lagoon may have adversely affected the gonad development of fish. In conclusion, this study is the first histological evidence of reproduction disturbance related to pollution pressure in a fish species inhabiting Bizerta lagoon. The high levels of gonad histopathology recorded raise concerns about the long-term health of fish populations in this lagoon.     

Restoration ecology of coastal lagoons: new methods for the prediction of ecological trajectories and economic valuation

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Nitrogen and phosphorous budgets during a farming cycle of the Manila clam Ruditapes philippinarum: An in situ experiment

In the Sacca di Goro lagoon a farming cycle of the Manila clam (Ruditapes philippinarum) was simulated seeding young molluscs in an unexploited sandy spot. The experimental area (2100 m²) consisted of three sectors: a control (C), almost devoid of clams (∼ 1600 m^− 2, ∼ 30 ind m^− 2), a low (L) density area (400 m², ∼ 300 ind m^− 2) and a high (H) density zone (∼ 110 m^− 2, ∼ 800 ind m^− 2). Water chemistry, external freshwater nutrient loads, molluscs filtration rates, biomass, elemental composition and nutrient recycling were analysed.Clam filtration rates and light and dark fluxes of nutrients were measured with intact core incubations. Three replicate cores (i.d. 20 cm) were collected from C, L and H in April, one month after the seeding, June, August and October 2003. External loads were calculated multiplying dissolved and particulate nutrients concentration by freshwater flow from the main lagoon tributaries. Direct excretion, filtration activity of clams and particulate matter deposition resulted in significantly higher ammonium (NH₄⁺) and soluble reactive phosphorus (SRP) effluxes to the water column at L and H. For the entire farming cycle, particulate nitrogen (PN) uptake by clams from the water column was 1.7 (C), 9.1 (L) and 16.3 (H) mol m^− 2, whilst total dissolved nitrogen (TDN) fluxes were − 0.3 (C), 1.6 (L) and 6.9 (H) mol m^− 2. Particulate phosphorus (PP) uptake from the water column was 0.1 (C), 0.6 (L) and 1.0 (H) mol m^− 2, whilst total dissolved phosphorus (TDP) efflux was 0.2 (C), 0.5 (L) and 0.8 (H) mol m^− 2. At the end of the farming cycle, harvested N as mollusc flesh was negligible for C, 0.4 mol m^− 2 for L and 1.8 mol m^− 2 for H. Harvested P as mollusc flesh was negligible for C, 0.02 mol m^− 2 for L and 0.04 mol m^− 2 for H. Farmed areas seem to have a great potential for fast coupling between sedimentation (filter feeder mediated biodeposition) and benthic recycling. At the lagoon level, mollusc farming probably attenuates the export of particulate matter to the open sea. Our results show that a minor fraction of biodeposited N (∼ 6%) and P (∼ 3%) was exported as a commercial product at the end of the farming cycle, whilst a larger fraction was incorporated in the sediments or recycled as dissolved inorganic or organic forms.     

The possible influence of sea level rise on the precarious dunes of Devesa del Saler Beach,Valencia, Spain

The Saler Beach dune field in Spain was partially destroyed between 1970 and 1973 due to building development. Presently great efforts to restore some dunes has begun. The possible consequence of a sea level rise for the Saler dune field is discussed according to different scenarios.     

Discards from the artisanal shrimp fishery in a tropical coastal lagoon of Mexico: spatio-temporal patterns and fishing gear effects

Abstract  Variability in community (richness, diversity and evenness) and population (size structure) attributes of discards was evaluated in a shrimp fishery in Celestun Lagoon, Mexico, in different climatic seasons and hydrological zones. Sampling was conducted using two bottom nets with different mesh size codends: 1.3 cm (used in the fishery) and 2.5 cm. Although the shrimp:discard ratio was 1:1 in both cases, total biomass and abundance with the 1.3-cm mesh size were, respectively, 4.6 and 1.8 times higher than with the 2.5-cm mesh size. This result was consistent in time and space. Discards were dominated by fishes [60% in 1.3-cm mesh size and 96% in 2.5-cm mesh size, mainly Cichlasoma urophthalmus (Günther), Eucinostomus gula (Quoy & Gaimard) and Lucania parva (Baird & Girard)] and shellfishes (40% in 1.3-cm mesh size and 4% in 2.5-cm mesh size, mainly Palaemonetes spp. and Callinectes spp.). The highest discards were registered the nortes season with both mesh sizes. The 1.3-cm mesh size retained significantly smaller sizes than the 2.5-cm mesh size in six of the eight most important species. An increase in mesh size, together with a fishery closure during the nortes season, are suggested to mitigate the impact of the fishery on the discarded fauna.