Lagoon Resident Fish Species of Conservation Interest According to the Habitat Directive (92/43/CEE): A Review on Their Potential Use as Ecological Indicator Species

Transitional waters are fragile ecosystems with high ecological, social and economic values, that undergo numerous threats. According to the information provided by European Member States in the framework of the European Directive 92/43/EEC (Habitat Directive), the main threat to these ecosystems is represented by morphological and hydrological changes. The present work focuses on six lagoon fish species included in the Habitat Directive annex II (species requiring conservation measures: Aphanius fasciatus, A. iberus, Knipowitschia panizzae, Ninnigobius canestrinii, Valencia hispanica and V. letourneuxi) that spend their entire life cycle in the Mediterranean priority habitat 1150* “Coastal lagoons”. The overview of the current scientific literature allowed us to highlight how the presence and abundance of these species may provide important indications on the conservation status of coastal lagoon habitats. In fact, their occurrence, distribution and biology depend on the presence of peculiar structures, such as salt marshes, small channels, isolated pools and oligohaline areas. Coastal lagoon fragmentation and habitat loss have led to a significant reduction in genetic diversity or local population extinction. Although Aphanius and gobies have been shown to survive in eutrophic environments, it is clear that they cannot complete their life cycle without salt marshes (mainly Aphanius) and wetland areas (mainly gobies)

HISTORICAL RECONSTRUCTION OF FISHERY CATCHES FOR THE LAKE GARDA

Fishery activities in the Garda lake had historically played a very important role for the people living along the coasts of the lake. In this work we present updated time series of catches, that could be useful to describe the evolution of the fishery, linking landings with the changes of environmental conditions and biological communities reported in the literature. Total catches peaked in the mid ’60s (ca. 700 metric tons) and then smoothly decreased until the ‘90s, when they started oscillating around a total production of about 400 metric tonnes, similarly to the situation observed before the ‘50s. However, catches composition shows more complex dynamics over time, with the disappearance over the years of species very important for the lake ecosystem and for the fishery itself, both in terms of catches or economic value (e.g. the Common bleak Alburnus alborella or the Carpione del Garda Salmo carpio). Even if some of the zooplankivourous species showed strong declines over time, this feeding category has always been very important for the lake fishery, representing at least 50% of the total caught biomass and reaching more than 80% of total catches since 1980. This is due to the large contribution of the Agone Alosa agone, that has been very important in the whole history of the fishery of the lake, and of the European whitefish Coregonus lavaretus, whose contribution changed over the decades, but that is characterized by an increase in the last period, becoming the most important species during the last decade

IMPLEMENTATION OF THE HABITAT FISH BIO-INDICATOR IN TWO WATER BODIES OF THE VENICE LAGOON: THE ROLE OF SEASONAL AND ENVIRONMENTAL VARIABILITY IN THE ASSESSMENT OF ECOLOGICAL STATUS OF FISH FAUNA

Under the Water Framework Directive (WFD; Dir. 2000/60/EC), fish are one of the Biological Quality Elements that need to be taken into account when evaluating the Ecological Status of transitional water bodies. The Habitat Fish Bio-Indicator (HFBI), a multi-metric index composed of six descriptors based on functional traits of fish assemblages, was recently developed to assess Italian transitional waters. In this study, HFBI was applied, following the national application protocol, to two water bodies in the Venice lagoon featuring different water and sediment physco-chemical properties and habitat distribution. The analysis highlighted that, in addition to seasonality, environmental variability along confinement gradients and presence and extent of seagrass meadows strongly influence the six metrics, the HFBI score and the subsequent assessment outcome. The selection of number and location of sampling sites must then be based on environmental characteristic and variability found within each water body, and is therefore a crucial step in the evaluation of Ecological Status in transitional water ecosystems

Fish Response to Multiple Anthropogenic Stressors in Mediterranean Coastal Lagoons: A Comparative Study of the Role of Different Management Strategies

Transitional waters are among the most productive ecosystems of the world and their biotic communities show high diversity and complex mechanisms of self-regulation that provide valuable ecosystem services and societal goods and benefits. In this work a comparison of the fish assemblages of three non-tidal Mediterranean coastal lagoons is carried out in order to evaluate the impacts of alternative management strategies. The anthropogenic pressures acting on the lagoons were quantified by means of categorical indicators, while the characteristics of the fish assemblages were summarized in multi-metric indices (MMIs). Two MMIs were developed using data collected with a beach seine net and with fyke nets, following an empirical approach that selects, from a pool of 73 metrics, the combination that maximizes the MMI/pressure relationship. The two MMIs include four metrics each, most of which are based on feeding mode functional guilds and habitat use functional guilds, and they are sensitive to anthropogenic pressures. The human activities directly or indirectly affecting water quality are the ones that most influence the fish assemblage, while the presence of artisanal fisheries, a typical and relevant resource use in these lagoons, seems to play a beneficial role. Lagoon fisheries management relies on the maintenance of infrastructures that guarantee the hydraulic functioning of the lagoon, thus ensuring exchanges with the adjacent coastal sea, and therefore indirectly contributing to the habitat quality

FISH FAUNA IN THE VENICE LAGOON: UPDATING THE SPECIES LIST AND REVIEWING THE FUNCTIONAL CLASSIFICATION

This work aims at reviewing the existing ecological classification of fish fauna in the Venice lagoon, and updating the list of species found during 15+ years of research in this ecosystem. The checklist encompass all fish life stages including ichthyoplankton, and contains 94 taxa, with 14 recorded only after 2010. The new functional classification, made of eight guilds including two guilds of lagoon residents and two of marine migrants, highlights the differences in species’ use of lagoon habitats in different seasons

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

DISTRIBUTION OF THE ALIEN SPECIES PALAEMON MACRODACTYLUS RATHBUN, 1902 IN THE VENICE LAGOON

Palaemon macrodactylus Rathbun (1902) is an estuarine shrimp native to north-western Pacific which, due to its wide environmental tolerance to chemical-physical conditions and its long breeding period, from 1957, probably carried by ship ballast water, massively colonized estuarine ecosystems worldwide. After its first record, in 2012, P. macrodactylus appears to have rapidly colonized the entire Venice lagoon, showing higher abundance in the confined saltmarsh stations of the northern sub-basin, probably due to the relatively low salinities values of this area. Records collected from 2014 to 2020 confirm the long reproductive period, comprised between Spring (mid-April) and Autumn (October), and the potential large invasion capacity of this species, which in the future could provoke competition with autochthonous species of the genus Palaemon and Crangon crangon

APPLICATION OF THE HABITAT FISH BIOLOGICAL INDEX (HFBI) FOR THE ASSESSMENT OF THE ECOLOGICAL STATUS OF PO DELTA LAGOONS (ITALY)

Fish fauna is one of the biological quality elements useful for assessing the ecological status of European transitional water bodies, for the purposes of applying the Water Framework Directive. For the assessment of the ecological status of Italian transitional aquatic ecosystems, the multimetric index “Habitat Fish Bio-Indicator” (HFBI), based on fish fauna, was developed and validated at national level. This paper reports the results of a study on the shallow-water fish fauna of 5 lagoon environments of the Po Delta (Northern Adriatic, Italy) which aimed to evaluate the ecological status of these water bodies by calculating the HFBI. The results made it possible to describe the taxonomic composition and the functional and trophic structures of the fish community characteristic of these delta lagoons. The shallow water fish assemblage was characterized by the presence of juvenile stages of marine migrating species (i.e., grey mullets of the genus Chelon, the sea bream Sparus aurata and the sea bass Dicentrarchus labrax) and by species of estuarine residents (i.e., small gobies Knipowitschia panizzae, Pomatoschistus marmoratus, and P. canestrinii, the silverside Atherina boyeri and the killfish Aphanius fasciatus). The guilds of hyperbentivores/zooplanktivores, microbentivores and detritivores were the most represented in the fish assemblage of the of investigated lagoons. The HFBI index, applied on an annual basis, made it possible to highlight marked differences in the ecological status of the Po Delta lagoons. Only Caleri lagoon resulted in a good state, Marinetta and Canarin lagoons in a moderate state, while Barbamarco and Scardovari lagoons resulted in a poor ecological state. Eutrophication, resulting from the large inputs of nutrients with freshwater from the Po River branches, and the modification of lagoon morphologies, a consequence of anthropogenic activities, are the main pressure factors that determine the ecological status of these transitional water bodies

Using fish assemblage to identify success criteria for seagrass habitat restoration

A fish-based multimetric index was applied to assess the ecological status of fish fauna in both natural and newly restored seagrass meadows in the Venice lagoon (northern Adriatic Sea, Italy), using natural habitats as reference sites. Fish assemblages were then compared, and community attributes of recreated and natural habitats were evaluated. Ecological status resulted higher in natural meadows, and a multivariate analysis showed that an increase in the relative proportion of seagrass specialists at restored sites could represent an indicator of success of seagrass restoration

La pesca artigianale in laguna di Venezia. Guida di buone pratiche e tutela della biodiversità

Questa guida illustra i risultati del progetto “Valutazione e miglioramento del grado di sostenibilità ambientale della pesca artigianale nei siti Natura 2000 della laguna di Venezia - 02/AIRBC/2018”, intervento finanziato dal PO FEAMP 2014-2020, il cui obiettivo principale è stato quello di promuovere la sostenibilità ambientale della pesca tradizionale con reti fisse in laguna di Venezia in un’ottica di tutela della biodiversità lagunare. Il progetto ha previsto: • Il monitoraggio mensile delle attività di pesca tradizionale durante l’autunno 2020 e la primavera 2021, in tre differenti aree di pesca della laguna di Venezia. • La caratterizzazione ambientale delle aree di pesca, sia mediante il rilevamento dei principali parametri dell’acqua, sia mediante l’analisi di immagini satellitari ad alta risoluzione che hanno permesso di effettuare la mappatura dei diversi tipi di habitat. • La sperimentazione, in una delle tre aree di pesca, di attrezzi modificati al fine di migliorarne la selettività di cattura, per ridurre l’impatto sulle specie protette e sugli individui giovanili di specie di interesse per la pesca, e contenere gli effetti negativi della presenza della specie aliena invasiva Mnemiopsis leidyi (noce di mare) e dei rifiuti galleggianti. Le attività di monitoraggio hanno permesso di mappare la distribuzione e determinare la stagionalità delle catture della pesca artigianale nelle tre aree di pesca considerate, rilevando e quantificando l’eventuale presenza e abbondanza di specie aliene nel pescato. Questa attività ha permesso anche di monitorare i rifiuti che periodicamente risultano presenti nelle reti. La sperimentazione di attrezzi da pesca modificati ha permesso di valutarne l’efficacia in termini di riduzione degli impatti della pesca sulla biodiversità lagunare e sulle risorse biologiche stesse. Questi attrezzi si sono anche rilevati efficaci per ridurre l’impatto negativo della noce di mare sulla pesca artigianale con reti fisse. Tutte le attività sono state rese possibili grazie alla fattiva collaborazione dei pescatori professionisti operanti nelle tre aree di pesca considerate. I pescatori artigianali per primi riconoscono la diversità ambientale all’interno del bacino lagunare come uno dei fattori chiave per la loro attività. In questa guida ci si è soffermati particolarmente sul ruolo che le diverse caratteristiche delle acque, dei fondali e delle morfologie del paesaggio lagunare svolgono per le specie ittiche bersaglio della pesca, e di conseguenza sull’importanza di tutelare gli habitat di tali specie. La presenza pressoché costante e diffusa nel bacino lagunare dei pescatori artigianali fa di essi importanti presidii sul territorio, da sempre sensibili e attenti ai cambiamenti che continuamente avvengono in laguna. I pescatori, se adeguatamente motivati e incentivati, potrebbero contribuire alla gestione dell’ambiente lagunare, in particolare sia nell’ambito del monitoraggio e del controllo delle specie aliene, sia nella gestione dei rifiuti dispersi nell’ambiente. Lo scopo di questa guida è quello di mostrare le potenzialità della pesca tradizionale in laguna di Venezia, non solo come esempio di sfruttamento sostenibile delle risorse biologiche lagunari, ma anche come attività che può effettivamente contribuire ad una gestione ambientale finalizzata alla conservazione della biodiversità lagunare