Management and Exploitation of Macroalgal Biomass as a Tool for the Recovery of Transitional Water Systems

Aquatic angiosperms favor the development of ecosystems services, the welfare of marine organisms and people. Generally, the presence of angiosperms in transitional water systems (TWS) are indicators of good ecosystem status. Presently, these environments are densely populated and often are so highly degraded that angiosperms have almost disappeared, replaced by tionitrophilic macroalgae responsible of anoxic events that deteriorate the environment furtherly. Although this trend is hardly reversible because the anthropogenic impact is increasing and the restoring of damaged environments within a reasonable time is difficult, recent studies have shown that by managing the harvesting of the natural algal species of commercial interest a progressive environmental recovery is achievable. Biomass-harvesting can contribute both to the removal of high amounts of nutrients and the generation of economic revenues for a sustainable, self-financed environmental restoration. In fact, unlike clam-farming which destroys the seabed and re-suspends large amounts of sediments, the proper management of the macroalgal biomass, can favor the nutrient abatement and the recolonization of aquatic angiosperms which help restore the conditions necessary for the conservation of the benthic and fish fauna and birds, and produce valuable economic resources

Assess the environmental health status of macrophyte ecosystems using an oxidative stress biomarker. Case studies: The Gulf of Aqaba and the Lagoon of Venice

Abstract The aim of this work was to evaluate the implementation of the oxidative stress biomarker (LPO) for the assessment and monitoring of the ecological status of macrophyte in relation to potentially toxic elements (PTEs) in the Gulf of Aqaba (Jordan) and the Lagoon of Venice (Italy). Results showed that the anthropic influences related to PTEs of the examined areas are evident. Moreover, changes in the LPO levels can precede significant changes in ecological health status of macrophyte ecosystems that can be used in the future as an early warning tool for the assessment and monitoring of polluted ecosystems worldwide

Benthic studies in LTER sites: the use of taxonomy surrogates in the detection of long-term changes in lagoonal benthic assemblages

In benthic studies, the identification of organisms at the species level is known to be the best source for ecological and biological information even if time-consuming and expensive. However, taxonomic sufficiency (TS) has been proposed as a short-cut method for quantifying changes in biological assemblages in environmental monitoring. In this paper, we set out to determine whether and how the taxonomic complexity of a benthic assemblage influences the results of TS at two different long-term ecological research (LTER) sites in the Po delta region (north-eastern Italy). Specifically, we investigated whether TS can be used to detect natural and human-driven patterns of variation in benthic assemblages from lagoonal soft bottoms. The first benthic dataset was collected from 1996 to 2015 in a “choked” lagoon, the Valli di Comacchio, a lagoon characterised by long water residence times and heavy eutrophication, while the second was collected from 2004 to 2010 in a “leaky” lagoon, the Sacca di Goro, a coastal area with human pressure limited to aquaculture. Univariate and multivariate statistical analyses were used to assess differences in the taxonomic structure of benthic assemblages and to test TS on the two different datasets. TS seemed to work from species to family level at both sites, despite a higher natural variability of environmental conditions combined with multiple anthropogenic stressors. Therefore, TS at the family level may represent effective taxonomic surrogates across a range of environmental contexts in lagoon environments. Since the structure of the community and the magnitude of changes could influence the efficiency of taxonomic surrogates and data transformations in long-term monitoring, we also suggest periodic analyses at finer taxonomic levels in order to check the efficiency of the application of taxonomic substitutes in routine monitoring programmes in lagoon systems

Long-term changes of the trophic status in transitional ecosystems of the northern Adriatic Sea, key parameters and future expectations: The lagoon of Venice as a study case.

The determination of the trophic status of transitional ecosystems from the physico-chemical and biological point of view is one of the requirements of the European Water Framework Directive (WFD 2000/60/EC). In Italy, its determination is implemented by the Regional Agencies for Environmental Protection (ARPAs) that have activated multi-annual monitoring programs. However, as the availability of funds is increasingly scarce, the number of environmental parameters to detect environmental changes should be conveniently managed. The high number of environmental parameters, nutrient and macrophyte datasets available for the LTER-Italia site “Venice lagoon” can be an useful tool to analyze the trophic changes over recent years and to foresee environmental evolutions. Nutrient data on a spatial basis have been available since 1948, whereas macroalgal maps date back to 1980. The aim of this paper is to highlight the changes of the trophic status of the lagoon since the middle of the 20th century by considering the concentrations of nutrients in the surface sediments and in the water column, the variation of some physico-chemical parameters and the biomass of macroalgae and also to foresee the way it will possibly evolve. In fact, after many anthropogenic impacts that in the second half of the 20th century affected the lagoon, starting fromthe year 2010, the ecological status is progressively improving. Nutrients show a significant reduction both in the water column and in surface sediments, and the macrophytes are represented by species of higher ecological value while the opportunistic species such as the Ulvaceae are in strong regression

Additional taxonomic coverage of the doubly uniparental inheritance in bivalves: Evidence of sex-linked heteroplasmy in the razor clam Solen marginatus Pulteney, 1799, but not in the lagoon cockle Cerastoderma glaucum (Bruguière, 1789)

In animals, doubly uniparental inheritance (DUI) is a major exception to the common strict maternal inheritance of mitochondria. To date, DUI has only been found in many bivalve species, but its distribution is still unclear. Given the great species richness of the class, much effort is needed to further investigate the occurrence of DUI in unsampled species. A compelling evidence of DUI is generally the presence of a sex-linked heteroplasmy, where two divergent mitochondrial lineages are found: One is isolated from the male germline, and the other one is isolated from the female germline and, normally, from the soma of both sexes. In the present study, we investigated the sex-linked heteroplasmy in the razor clam Solen marginatus Pulteney, 1799 and in the lagoon cockle Cerastoderma glaucum (Bruguière, 1789) using two mitochondrial markers (cox1 and rrnL). We found evidence of DUI in the species S. marginatus, with a divergence up to 21% for the rrnL gene, but not in C. glaucum. Moreover, our phylogenetic reconstruction includes all the available data for heterodont species with sex-linked heteroplasmy and suggests multiple origins of DUI in this subclass, as well as the presence of DUI in other species of the genus Solen

Makrofiti i procjena ekološkog stanja u prijelaznim vodama delte rijeke Po, Jadransko more (Italija). Primjena Indeksa kvalitete makrofita (MaQI)

The paper provides the first checklist and information on the macrophytes of the Po Delta (Italy), a complex of small lagoons and ponds among the largest in the Mediterranean Sea, until now little studied in spite of the water surface of approx. 200 km². The abundance and assemblage composition of macrophytes that colonize these environments and their ecological status have been studied taking into account the most common physico-chemical parameters and the concentration of nutrients in the water column and in the surface sediment. Sampling was carried out in 17 sites, placed at Marinetta, Vallona, Caleri, Canarin, Barbamarco and Scardovari lagoons, during two surveys on 13-15 May and 13-15 October 2008. The ecological status was assessed by applying the Macrophyte Quality Index (MaQI) which was adopted by the Italian Ministry of the Environment for the ecological classification of the Italian transitional environments, in agreement with the Water Framework Directive (2000/60/EC) requirements.U radu se iznose prvi popis i informacije o makrofitima u delti rijeke Po (Italija) koja se sastoji od brojnih malih laguna i ribnjaka i koja je jedna od najvećih u Sredozemnom moru, koja je do sada slabo istraživana unatoč činjenici što obuhvaća površinu vode od cca. 200 km². Istraživan je ekološki status, brojnost i skupni sastav makrofita koji naseljavaju ovo okruženje uzimajući u obzir najuobičajenije fizikalno-kemijske parametre i koncentraciju nutrijenata u vodenom stupcu i površinskom sloju sedimenta. Tijekom dva ispitivanja obavljena između 13. i 15. svibnja i 13. i 15. listopada 2008. provedeno je uzorkovanje na 17 mjesta raspoređenih u lagunama Marinetta, Vallona, Caleri, Canarin, Barbamarco i Scardovari. Ekološko stanje procijenjeno je primjenom Indeksa kvalitete makrofita (MaQI) kojeg je usvojilo Ministarstvo zaštite okoliša za ekološku klasifikaciju talijanskih prijelaznih područja u skladu sa zahtjevima Okvirne direktive o vodama (2000/60 EC)

Aquatic Angiosperm Transplantation: A Tool for Environmental Management and Restoring in Transitional Water Systems

Since the 1960s, the Venice Lagoon has suffered a sharp aquatic plant constriction due to eutrophication, pollution, and clam fishing. Those anthropogenic impacts began to decline during the 2010s, and since then the ecological status of the lagoon has improved, but in many choked areas no plant recolonization has been recorded due to the lack of seeds. The project funded by the European Union (LIFE12 NAT/IT/000331-SeResto) allowed to recolonize one of these areas, which is situated in the northern lagoon, by widespread transplantation of small sods and individual rhizomes. In-field activities were supported by fishermen, hunters, and sport associations; the interested surface measured approximately 36.6 km2. In the 35 stations of the chosen area, 24,261 rhizomes were transplanted during the first year, accounting for 693 rhizomes per station. About 37% of them took root in 31 stations forming several patches that joined together to form extensive meadows. Plant rooting was successful where the waters were clear and the trophic status low. But, near the outflows of freshwater rich in nutrients and suspended particulate matter, the action failed. Results demonstrate the effectiveness of small, widespread interventions and the importance of engaging the population in the recovery of the environment, which makes the action economically cheap and replicable in other similar environments

Trends of Nitrogen and Phosphorus in Surface Sediments of the Lagoons of the Northern Adriatic Sea

The analysis of nutrient concentrations in surface sediments is a reliable tool for assessing the trophic status of a water body. Nitrogen and phosphorus concentrations are strongly related to the sediment characteristics but are mainly driven by anthropogenic impacts. The results of the determination of total nitrogen and total inorganic and organic phosphorus in surface sediments of the lagoons and ponds of the northwestern Adriatic Sea (Marano-Grado, Venice, Po Delta, Comacchio Valleys, Pialassa della Baiona) show the merit of this approach. Indeed, when previous data are available, the ratio between the actual and background values can provide useful information on the trophic changes that have occurred in the most recent times, and the results can also explain the conditions present in less studied environments. In this context, numerous studies performed in the Venice lagoon since the second half of the 20th century during different environmental scenarios provide mean concentration ranges and propose the main causes of changes. The results of single datasets available for the other lagoons fall into scenarios that occurred in the Venice lagoon. At present, the most eutrophic basins are Pialassa della Baiona, the Po Delta lagoons and ponds and the Comacchio valleys due to industrial effluents, fish farming and clam harvesting, respectively, whereas the Venice lagoon is now experiencing environmental recovery

Hazardous effects of silver nanoparticles for primary producers in transitional water systems: The case of the seaweed Ulva rigida C. Agardh

Abstract The acute toxicity of citrate capped silver nanoparticles (AgNP) and silver nitrate was evaluated on the marine macroalga Ulva rigida C. Agardh (1823). Silver bioaccumulation, ultrastructural chloroplast damages verified by TEM microscopy, inhibition of primary production, neutral lipid production and oxidative stress were observed after 24 h of exposure to AgNP. The toxic effects of silver nitrate in artificial seawater started from a concentration of 0.05 ppm and was more toxic than AgNP that produced effects from a concentration of 0.1 ppm. However only AgNP induced lipid peroxidation in U. rigida. The addition of natural organic and inorganic ligands, represented by transparent exopolymer particles (TEP) and clay, drastically reduced AgNP acute toxicity in a ratio AgNP:ligand of 1:100 and 1:200, respectively. The findings suggest a marked toxicity of Ag on marine macroalgae which however should be mitigated by the high natural ligand concentrations of the transitional environments

Sastav i raspodjela fitoplanktonske zajednice u eutrofnom obalnom području (Venecijanska laguna, Italija)

We investigated the phytoplankton in the central area of the Venice lagoon in the 1990s. Water samples were collected at 46 sites in June 1993 and June 1998 and at four stations every month from November 1998 to October 1999. Collected data include community composition, cell abundance, and cell bio-volumes, estimated with an inverted light microscope. Cell abundance distribution maps display mean (6.9 x 106 and 2.5 x 106 cells dm-3 in June 1993 and June 1998, respectively) and peak values (151 and 16 x 106 cells dm-3 in June 1993 and June 1998, respectively). The reasons for differences in blooming taxa were investigated by processing environmental variables of the most abundant taxa by Canonical Correspondence Analysis. The environmental parameters that most affected the species spatial distribution were salinity and temperature in June 1993 and salinity and water transparency in June 1998. Phytoplankton temporal trends confirmed the spatial distribution: the blooming period was in June and the highest cell abundances occurred close to the mainland.Istraživanja fitoplanktona središnjeg dijela Venecijanske lagune su izvršena devedesetih godina. Uzorci mora sakupljani su na 46 postaja u lipnju 1993. i u lipnju 1998. godine, a na 4 postaje jedanput mjesečno od studenog 1998. do listopada 1999. godine. Sakupljeni podaci uključuju sastav zajednice, numeričku abundanciju i stanične volumene, određene obrnutim svjetlosnim mikroskopom. Raspodjela abundancije stanica bila je u prosjeku 6,9 x 106 i 2,5 x 106 dm-3 u lipnju 1993. godine, odnosno lipnju 1998., a maksimalne vrijednosti od 151 i 16 x 106 dm-3 u lipnju 1993., odnosno lipnju 1998. Razlozi za razlike vrsta u cvatnji proučavani su u odnosu na faktore sredine (“Canonical Correspondence Analysis”). Najjači utjecaj na prostornu raspodjelu vrsta imali su slanost i temperatura mora u lipnju 1993. te slanost i prozirnost mora u lipnju 1998. S time se podudara i prostorna raspodjela fitoplanktona. Vrijeme cvatnje nastupalo je u lipnju, s najvišim vrijednostima neopsredno uz obalu