In situ metabolic budget for the calanoid copepod Acartia clausi in a tropical brackish water lagoon (Ebrié Lagoon,Ivory Coast)

Simultaneous measurements of respiration, excretion and production rates were carried out several times over a year period at five representative stations of the Ebrié Lagoon. Assuming a constant assimilation efficiency rate of 69.4%, we derived metabolic budgets for carbon, nitrogen and phosphorus. Daily specific ingestion rates calculated were rather generally high, and ranged between 54 and 159% of body carbon, between 26 and 102% of body nitrogen and between 108 and 307% of body phosphorus. Regional and seasonal variations depended mainly upon variations in trophic conditions. Curvilinear relationships between ingestion production, or net production efficiency K2, and food concentration (as chlorophyll-a + phaeopigments) showed that food could have been a limiting factor. Furthermore, K2 were low when compared with data from the literature (mean of 21% in carbon, 39% in nitrogen and 11% in phosphorus).Complementary laboratory experiments carried out on adults fed with enriched natural particles or algal cultures (Tetraselmis sp. or Dunaliella sp.) showed similar production (egg-production) vs food concentration curvilinear relationships as in the field. However, considerably higher maximal ingestion and production rates were obtained for animals fed algal cultures suggesting that optima for food acquisition and transformation were not reached in field conditions.Consequently, A. clausi, which represents more than 50% of the zooplankton biomass, appears to be rather inefficient in transforming the abundant particulate organic matter produced in the lagoon. This results from its high level of metabolic expenditure through respiration or excretion (about 50% of ingestion in terms of carbon) and from the small size and poor trophic value of food particles (high percentage of detritus).     

The use of Cerastoderma glaucum as a sentinel and bioindicator species: Take-home message

Bivalves are frequently used to assess environmental contamination, and are often considered good sentinel and/or bioindicator species. For that reason the bioaccumulation and toxicity induced by metals and As in the cockle Cerastoderma glaucum, collected from areas with different contamination levels along the Óbidos lagoon (Portugal), were used to evaluate the use of this species as sentinel and/or bioindicator. The results showed that areas in the middle of the lagoon presented lower metals and As concentrations, lower total organic matter content and lower percentage of fine particles than areas in the Bom Sucesso arm. In all areas Cr, Pb and Cu were the most abundant elements, while Ni, As, Cd and Hg were less abundant. Results also showed a moderate correlation between total elements concentrations found in C. glaucum and in sediment, and thus caution should be taken when considering this species as a good sentinel species. The present study also revealed that, in general, C. glaucum from areas in the middle of the lagoon accumulated higher concentrations of metals and As (Biota-Sediment Accumulation Factor >1) than cockles from the most polluted areas located in the Bom Sucesso arm. However, in all areas, the majority of metals (Cu, Cr, Pb) were found in cockles insoluble fraction which may explain low cellular damage and reduced oxidative stress responses observed. Therefore, our results may further alert for caution when identifying C. glaucum as a good bioindicator species. Thus, our findings highlight the fact that studies should be cautious when selecting species for environmental monitoring, since good sentinels or bioindicators in highly polluted systems may not act in the same way in low or moderately contaminated areas. Furthermore, our study warns for the misclassification of cockles in different ecosystems.     

Remediation of Thiothrix spp. associated bulking problems by raw wastewater feeding: A full-scale experience

An industrial wastewater treatment plant (WWTP) in Australia has long suffered from bulking problems associated with the proliferation of Thiothrix spp. The WWTP consists of a covered anaerobic lagoon (CAL) followed by a sequencing batch reactor (SBR). The CAL functions as both an anaerobic digester and surge lagoon for the irregular flow of wastewater generated from the production of seasonal products. Chemical analysis of the raw influent showed it was composed of a mixture of organic acids, phenols and alcohols. The CAL effluent was characterised by high acetic acid and phenolic concentrations. An attempt was made to manipulate the SBR microbial community to improve settling by direct feeding small volumes of raw influent into the SBR. After raw feeding, the plant ceased bulking as the settled sludge volume reduced from 930 to 200 mL L^?1. 16S rRNA gene profiling and biovolumes of SBR samples revealed major changes in the microbial community. The Thiothrix spp. population decreased from 36.8% to 0.2%, and Zoogloea spp. dominated all samples after raw feeding. Therefore, direct feeding is proposed as a control method for industrial plants with surge/anaerobic lagoons in order to manage the bulking problems caused by Thiothrix spp. in downstream SBRs.     

Can Coral Cover be Restored in the Absence of Natural Recruitment and Reef Recovery?

With many coral reef areas being degraded whether by anthropogenic or natural causes, a search is on for resilient species of corals that can restore coral cover where needed, if coral reefs are to continue to provide adequate ecosystem services. A series of experiments were undertaken in two sites with different environmental attributes and substrates in a lagoonal area in the northwestern Philippines to test the potentials of a local species, Porites cylindrica, for reef rehabilitation. With the use of asexual fragmentation of donor colonies, different treatments were tested, particularly to determine if the species would survive on different substrates, that is, solid, massive versus digitate/anastomosing, dead colonies. The results after nearly 2 years of the experiment were extraordinarily successful, with survival of transplants ranging from a high of 98% to a low of 80% of colonies, resulting in extensive coral cover on both original and new or different substrate from the original. A subsequent observation after another 16 months showed the coral cover to have been complete or nearly complete in the experimental plots, with the transplanted colonies fusing, and with evident reef fish communities where there were none before. Had there been no intervention, it is highly likely that the reefs would have remained in a degraded state .     

Fish Assemblages in Different Shallow Water Habitats of the Venice Lagoon

The small-sized fish assemblages of the Venice Lagoon were investigated and compared among five shallow subtidal habitats (seagrass beds, sparsely vegetated habitats, unvegetated sand bottoms, mudflats and saltmarsh creeks) in the Northern lagoon basin. Sampling was carried out seasonally (Spring, Summer and Autumn of 2002) in 4–7 stations for each habitat type, by means of a fine-mesh, small beach seine. Two-way analysis of variance was applied to assess the differences in species richness, fish diversity, density and standing stock amongst habitats, whereas fish assemblage composition was investigated by using multivariate analyses (MDS, ANOSIM, SIMPER). The analyses indicated that seagrass beds and saltmarsh creeks are relevant shallow habitats in structuring the small-sized fish assemblages of the Venice Lagoon, supporting specialized and recognizable fish assemblages. Those in seagrass beds, in particular, were characterized by higher species richness and standing stock with respect to all the others. The structuring role of these habitats was discussed in terms of both habitat complexity and degree of confinement. In contrast, sandy bottoms, mudflats and sparsely vegetated habitats were identified as “transition” habitats, with highly variable fish assemblages, influenced by the contribution of the adjacent habitats, and acting probably as both ‘buffer zones’ between the other habitats and migration routes for many fish species in the lagoon.     

Mysidacea (Crustacea) from the Minicoy lagoon (Lakshadweep, India) with description of a new species of Anisomysis

Four species of mysids collected from the Minicoy lagoon are reported. Anisomysis minicoyensis sp. nov. is distinguished from the related species by the shape of the rostrum, the relative length of the antennal scale and the short protuberances on the second segment of the mandibular palp. The other three species recorded are Siriella australiensis, Anisomysis truncata and unidentified species of subfamily Gastrosaccinae.     

Gamete compatibility between marine and estuarine Acanthopagrus spp. (Sparidae) and their hybrids

On Australia's south‐east coast, hybridization between estuary‐restricted black bream Acanthopagrus butcheri Munro and its migratory coastal congener yellowfin bream Acanthopagrus australis (Günther) has led to estuarine populations largely composed of hybrids that are most genetically similar to A. butcheri. The fertilization success achieved when ova of estuary‐caught A. butcheri were fertilized with the cryogenically preserved sperm of either ocean‐caught A. australis or estuary‐caught A. butcheri‐like was compared. The experimental crosses, which by chance included both pure parental and hybrid bream, revealed no evidence that gametic incompatibility provides a barrier to fertilization among both pure species and their hybrids.     

Environmental influences on the formation and germination of hibernacula in the brackish-water bryozoan Victorella pavida Saville Kent, 1870 (Ctenostomata: Victorellidae)

Brackish-water and fresh-water bryozoans produce asexually derived dormant propagules that allow survival of unfavourable conditions and provide a potential means of dispersal. The propagules of brackish-water ctenostome bryozoans are called hibernacula. We monitored the life-cycle of the brackish-water ctenostome Victorella pavida Saville Kent, 1870 in its natural habitat and investigated, in laboratory cultures, the influence of temperature and salinity on the production and germination of hibernacula and on subsequent colony growth. V. pavida is a protected species in the UK, where its only locality is at Swanpool lagoon, Falmouth. Colonies were collected from Swanpool monthly from January 2004 to January 2005. Hibernaculum germination appeared to be triggered by increased water temperature (c. 13 °C) in the lagoon in March and April. In culture, germination was triggered by transfer from 5 °C to 19 °C in a range of salinities; subsequent colony growth was affected by salinity, with strongest growth at 13, 18 and 36 psu, and reduced growth at 5 and 9 psu. At 3.5 psu, hibernacula germinated, but there was no further development. At 36 psu there was an initial lag in growth, but after 30 d the colonies were comparable with those kept at 18 psu. Hibernaculum formation by colonies occurred from June to October, with production increasing towards October. Hibernacula appear not to have long-term viability but merely to permit survival from one year to the next. The results suggest that any changes in the hydrographic regime at Swanpool could have significant consequences for the survival of V. pavida.     

The presence of exotic Hypnea flexicaulis (Rhodophyta) in the Mediterranean Sea as indicated by morphology, rbcL and cox1 analyses

Here we report the first finding of Hypnea flexicaulis Yamagishi and Masuda in the Mediterranean Sea (Lagoon of Venice, Italy), identified through molecular analyses using the plastid ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) and the mitochondrial protein-coding cytochrome c oxidase subunit I (cox1) genes. The phylogenetic reconstruction, based on rbcL + cox1 multiple alignment, showed that all specimens of H. flexicaulis from Venice, Korea, Philippines and Taiwan were included in a monophyletic group supported by a bootstrap value of 100%.It is highly probable that H. flexicaulis has been introduced from Indo-Pacific populations, in particular the Korean one, probably via ship traffic or shellfish transfers.The use of DNA barcoding combined with morphological observations was, in this case, a rapid way to identify this allochthonous species.     

Intra‐annual variation of the spatiotemporal distribution and abundance of Talitridae and Oniscidea (Crustacea,Peracarida) at Bizerte Lagoon (northern Tunisia)

During 1 year from spring 2007 to winter 2008, we conducted four seasonal samplings along a transect in the supralittoral zone of Bizerte Lagoon at Menzel Jmil (Tunisia) to study the intra‐annual variation of Peracarida diversity, Talitridae and Oniscidea. For each season, one transect was studied and quadrates were placed successively from the shoreline to the road backing the shore. Talitridae and Oniscidea were the most abundant taxa in our samples reaching highest densities in summer, when fourteen species were found. The minimum and maximum values of species richness of Talitridae were observed in winter (four species) and summer (eight species), respectively, while for Oniscidea, species richness ranged from one species in winter and five species in spring. Both Talitridae and Oniscidea exhibited intra‐annual variation in their spatial distribution; in that, they moved away from the shoreline in winter and were found near the waterline in the other seasons. ANOVA test shows a high significant correlation between both Talitridae with Suaeda maritima and Oniscidea with the plants S. maritima,Salicornia arabica and Obione portulacoides.