This article gives an up-to-date review of the status of and main changes in benthic algal flora that have occurred in recent decades along the Italian Adriatic coastline. Common traits among the main structural/functional changes observed and their causes are discussed.A synthesis of the challenges to and prospects of filling gaps in the data, ecological knowledge and protection measures are also given
Habitat classifications provide guidelines for mapping and comparing marine resources across geographic regions. Calcareous bio-concretions and their associated biota have not been exhaustively categorized. Furthermore, for management and conservation purposes, species and habitat mapping is critical. Recently, several developments have occurred in the field of predictive habitat modeling, and multiple methods are available. In this study, we defined the habitats constituting northern Adriatic biogenic reefs and created a predictive habitat distribution model. We used an updated dataset of the epibenthic assemblages to define the habitats, which we verified using the fuzzy k-means (FKM) clustering method. Redundancy analysis was employed to model the relationships between the environmental descriptors and the FKM membership grades. Predictive modelling was carried out to map habitats across the basin. Habitat A (opportunistic macroalgae, encrusting Porifera, bioeroders) characterizes reefs closest to the coastline, which are affected by coastal currents and river inputs. Habitat B is distinguished by massive Porifera, erect Tunicata, and non-calcareous encrusting algae (Peyssonnelia spp.). Habitat C (non-articulated coralline, Polycitor adriaticus) is predicted in deeper areas. The onshore-offshore gradient explains the variability of the assemblages because of the influence of coastal freshwater, which is the main driver of nutrient dynamics. This model supports the interpretation of Habitat A and C as the extremes of a gradient that characterizes the epibenthic assemblages, while Habitat B demonstrates intermediate characteristics. Areas of transition are a natural feature of the marine environment and may include a mixture of habitats and species. The habitats proposed are easy to identify in the field, are related to different environmental features, and may be suitable for application in studies focused on other geographic areas. The habitat model outputs provide insight into the environmental drivers that control the distribution of the habitat and can be used to guide future research efforts and cost-effective management and conservation plans.
Abstract\ud Benthic macrophytes from 19 sites within the Marano-Grado Lagoon were sampled in July 2007 in\ud order to update the available information on the flora and vegetation and to assess the Ecological\ud Status (ES) within the European Water Framework Directive (WFD). Data on macrophytes were\ud analysed using two phytobenthic indices (EEI and R-MaQI) recently set up to evaluate the\ud ecological status of transitional environments in the Mediterranean eco-region. Notwithstanding the\ud extension (c. 160 km2) that places this lagoon as the second largest Italian transitional environment,\ud ecological studies are relatively few. The present research revealed a relatively poor flora, mainly\ud characterized by the dominance of low-diversity settlements of Ulvaceae. Moreover, the absence of\ud intensive aquaculture activities and commercial big harbours, which account for the new species\ud introductions recorded in other lagoons, limits the presence of non-autochthonous species. The\ud comparison with previous data (Curiel et al. 1998) highlighted the reduction of macrophyte\ud coverage and biomass, especially Ulvaceae stands, and an increase in species richness. In particular,\ud there was evidence of a worsening of the area north of the Grado bridge. This area, which in the\ud past was colonized by widespread angiosperm coverage, at present is almost lacking in vegetation.\ud According to these observations, by applying both the phytobenthic indices available in the\ud literature for the transitional environments, the Marano-Grado Lagoon showed a ‘Good–High’\ud quality in the central part of the basin and near the lagoon inlets and a ‘Poor–Bad’ quality in the\ud northern and southern areas. The evaluation of some physicochemical parameters, coupled with the\ud distribution of the angiosperms, also allowed a first delineation of the main lagoon water bodies
We present a check-list of the seaweeds for Venice lagoon, based on literature and recent records. At present the total number of taxa is 277, including 71 Chlorophyceae s.l. (25.6%), 148 Rhodophyceae (53.4%), 56 Phaeophyceae (20.2%) and 2 Chrysophyceae (0.7%). Using present day taxonomy, the number of taxa is about double that in previous lists. Since 1983, there have been 92 (ca. 33%) new records for Venice littoral zone. Of these, 19 (ca. 21%) are first records for the Mediterranean Sea, and many are alien taxa that seriously compete with the growth of indigenous species. The number of taxa that have disappeared from the lagoon, or have not been found in the recent years, is 96.
SUMMARY: Over the past hundred years, the composition of the submerged aquatic vegetation of the Lagoon of Venice has changed considerably, due to increased anthropic activities and large-scale industrialisation. Seagrasses have gradually been reduced, whereas macroalgae (Ulva rigida, Enteromorpha spp., Cladophora spp., Chaetomorpha spp.) have increased. Macroalgal overgrowths peaked between 1970 and 1990 to the extent that, in order to estimate macroalgal biomass and coverage, the Venice Magistrato alle Acque (the Lagoon water management authority) started a series of investigations including monthly in situ measurements and aerial photo surveys. In the present paper these data are compared with available information on the Lagoon of Venice, and the widespread phenomenon of macroalgal proliferation is described. At the end of the 1980s, in our study area (78 km 2 in the central part of the Lagoon) biomass values ranged from 10 to 25 kg wet weight (w.w.) m -2 (sub-areas of Lido and Sacca Sessola), with a total mean biomass of 392,000 t w.w. A slight reduction took place in 1992 and at the end of the 1990s the highest biomass values were relatively low, 5 kg w.w. m -2 , with a total mean biomass of 1,600 t w.w. Our qualitative research carried out in 1991 on 130 sampling stations in the study area showed that soft substrates had a greatly reduced floristic composition in the five sub-areas in comparison with the control area (from 18 to 6 taxa), with Chlorophyta (50-80%) prevailing over both Rhodophyta (14-38%) and Phaeophyta (0-14%), and a slight or reduced distribution of seagrasses. The trend in macroalgal reduction during the 1990s corresponded to seagrass recolonisation, mainly of Zostera marina, taking advantage of new, compacted, oxidised and stabilised sediments that were no longer covered by extensive Ulva beds. [1981][1982][1983][1984][1985][1986][1987][1988][1989][1990][1991][1992][1993][1994][1995][1996][1997][1998]. -Durante los últimos cien años la composición de la vegetación acuática sumergida de la laguna de Venecia ha cambiado considerablemente a causa del incremento de actividades antrópicas y la industrialización a gran escala. Las fanerógamas marinas han reducido su extensión y las macroalgas (Ulva rigida, Enteromorpha spp., Cladophora spp., Chaetomorpha spp.) la han aumentado. El crecimiento de macroalgas alcanzó una cota máxima entre 1970 y 1990 hasta el extremo que la Agencia Veneciana del Agua inició una serie de proyectos para estimar la biomasa y el recubrimiento algal que incluían medidas mensuales en el campo y fotografías aéreas. En este trabajo estos datos se comparan con la información disponible de la laguna de Venecia, describiéndose las proliferaciones algales. A finales de los años 80, en nuestra área de estudio (78 km2 en la parte central de la laguna) las biomasas oscilaban entre 10 y 25 kg de peso húme-do por metro cuadrado (subáreas de Lido y Sacca Sessola) con una biomasa media de 392.000 Tm. Una leve disminución tuvo lugar en 1992, y, al final de los 90, las biomasas más...
We sampled macroalgal assemblages on 37 rocky outcrops in the northern Adriatic over the last 2 decades by SCUBA. Macroalgal assemblages were rich (173 taxa), but there was high variability in the number of species and coverage. The morphology of the outcrops, the distance from the coast and the depth were identified as the main factors accounting for this variability. Both the mean total algal coverage (14.8%) and encrusting layer coverage (8.0%) were low when compared to typical Mediterranean coralligenous habitats. Four main groups of algal assemblages were distinguished on the basis of their species composition and coverage. Groups 1 and 3 were located inshore off the Lido inlet and south of it, and had, respectively, low or intermediate total algal cover. Group 2 included outcrops situated offshore from the Venice lagoon along with all outcrops off the Grado-Marano lagoon; these had the highest total algal cover. Finally, group 4 included assemblages comprising algae that were widespread on outcrops in the inshore habitats of the Venice lagoon, between Malamocco and Chioggia inlets. Offshore outcrops subject to low turbidity and eutrophication levels had several characteristic Mediterranean coralligenous taxa
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