Impact assessment of fish cages on coralligenous reefs through the use of the STAR sampling procedure

The study aimed at contributing to the development of methods to assessing the effects of human disturbance on coralligenous reefs. The effects of the presence of a fish farm on coralligenous reefs were evaluated using the STAR (STAndaRdized coralligenous evaluation procedure) sampling procedure. An asymmetrical sampling design was used to compare the aquaculture site with two reference sites in areas unaffected by human pressure. The response of different ecological indices (ESCA, Ecological Status of Coralligenous Assemblages; ISLA, Integrated Sensitivity Level of coralligenous Assemblages; COARSE, COralligenous Assessment by Reef Scape Estimate) and descriptors (α-diversity, β-diversity and Sensitivity Level) of this kind of disturbance was compared. Results indicate that coralligenous reefs are vulnerable to aquaculture fish cages, and differences in the structure of coralligenous assemblages between the disturbed and the reference sites were mostly due to the decrease in β-diversity. On the contrary, no significant differences in the number of taxa/groups were highlighted. Encrusting Corallinales, erect Rhodophyta, Dictyotales, Fucales and Halimeda tuna were more abundant in reference sites than in disturbed site, while Peyssonnelia spp. and algal turfs had the opposite trend. Conversely, no significant differences between conditions were found in the abundance of sessile invertebrates. The study supports the suitability of the STAR approach to be employed in impact evaluation assessments, such as in monitoring programs. The present study is a first attempt to combine three different ecological indices (ESCA, ISLA and COARSE) within a unified approach, in order to assess the status of coralligenous reefs subjected to a moderate human-induced disturbance. The inconsistent response of the different indices highlights the advantage of applying different indices and descriptors to evaluate the variable human pressures on natural systems

Animal Forest Mortality: Following the Consequences of a Gorgonian Coral Loss on a Mediterranean Coralligenous Assemblage

In this work, the consequences of a local gorgonian coral mortality on the whole coralligenous assemblage were studied. A Before/After-Control/Impact sampling design was used: the structure of the coralligenous assemblage was compared before and after the gorgonian mortality event at the mortality site and two control sites. At the mortality site, a relevant decrease in alpha and beta diversity occurred, with a shift from a stratified assemblage characterized by gorgonians and other invertebrates to an assemblage dominated by algal turfs; conversely, neither significant variations of the structure nor decrease in biodiversity were observed at the control sites. The assemblage shift involved the main taxa in different times: in autumn 2018, a large proportion of the plexaurid coral Paramuricea clavata died, but no significant changes were observed in the structure of the remaining assemblage. Then, in autumn 2019, algal turfs increased significantly and, one year later, the abundance of the gorgonian Eunicella cavolini and bryozoans collapsed. Although the mechanisms of the assemblage shift following gorgonian loss will remain uncertain and a cause-effect relationship cannot be derived, results suggest the need for detecting signs of gorgonian forests stress in monitoring programs, which should be considered early indicators of their condition. in the coralligenous monitoring programs for detecting any sign of gorgonian forests stress which should be considered an early indicator of the assemblage condition

Effects of high temperature and marine heat waves on seagrasses: Is warming affecting the nutritional value of Posidonia oceanica?

9 pages, 5 figures, 4 tables.-- Under a Creative Commons licensePrimary producers nutritional content affects the entire food web. Here, changes in nutritional value associated with temperature rise and the occurrence of marine heat waves (MHWs) were explored in the endemic Mediterranean seagrass Posidonia oceanica. The variability of fatty acids (FAs) composition and carbon (C) and nitrogen (N) content were examined during summer 2021 from five Mediterranean sites located at the same latitude but under different thermal environments. The results highlighted a decrease in unsaturated FAs and C/N ratio and an increase of monounsaturated FA (MUFA) and N content when a MHW occurred. By contrast, the leaf biochemical composition seems to be adapted to local water temperature since only few significant changes in MUFA were found and N and C/N had an opposite pattern compared to when a MHW occurs. The projected increase in temperature and frequency of MHW suggest future changes in the nutritional value and palatability of leavesThis research was financially supported by Botany and Plant Science at University of Galway, by the project Marine Habitats Restoration in a Climate Change-impaired Mediterranean Sea [MAHRES] funded by the Italian Ministry of Research under the PRIN 2017 Program (Project N. 2017MHHWBN; CUP: 74I19001320001), by “Fondo di Ateneo per la Ricerca 2019” by the University of Sassari, by PON - National Operational Programme - Research and Innovation 2014–2020, PhDs and research contracts on innovation-related topics and by the project DRESSAGE (MIS5045792) (through the Operational Program ‘Competitiveness, Entrepreneurship and Innovation’ (EPAnEK 2014–2020)Peer reviewe

Caratterizzazione dei popolamenti coralligeni macroalgali dell'isola dell'Asinara e valutazione della qualita ecologica mediante l'indice ESCA

Il coralligeno è considerato, insieme alle praterie di Posidonia oceanica, l’habitat più importante del Mediterraneo (Ballesteros, 2006) grazie alla sua estensione, alla diversità delle specie, alla produttività e al ruolo che il coralligeno stesso ricopre nel ciclo del carbonato (Ballesteros, 2006; Laborel, 1961, 1987). Consiste in una struttura calcarea principalmente costruita da Rhodophyta appartenenti alle Corallinales (Ballesteros, 2006). Le alghe costruttrici sono coadiuvate nella loro impresa da spugne, madrepore, vermi tubicoli, molluschi sessili, crostacei, cirripedi e briozoi che consolidano e ampliano le impalcature algali. Il coralligeno è definito, nell’ambito della Marine Strategy Framework Directive, un “habitat speciale” la cui valutazione dello stato di qualità può contribuire alla definizione dello stato ambientale delle regioni o sub-regioni marine mediterranee (EC, 2008). A causa della loro condizione sessile ed alla loro capacità di integrare gli effetti di un’esposizione a lungo termine a sostanze inquinanti con un cambiamento della struttura degli assemblaggi, le macroalghe bentoniche presenti nella comunità del coralligeno, riconosciute come BQE (Elementi di Qualità Biologica) dalla WFD (EC, 2000), sono state indicate come uno degli elementi chiave da considerare per la determinazione dello stato di qualità ecologica dei corpi d’acqua costieri nell’European Water Framework Directive (Orfanidis et al., 2003; Ballesteros et al., 2007). Il presente studio ha come obiettivo la valutazione ecologica del Coralligeno dell’isola dell’Asinara, Sardegna, con l’utilizzo dell’indice di qualità ESCA (Ecological Status of Coralligenous Assemblages) (Cecchi, 2014). Tale indice si basa su dati ottenuti da campioni fotografici quali: Sensitivity level (SL), α-diversità, β-diversità. Il valore SL è calcolato in base a dati di presenza/assenza ed abbondanza di taxa sensibili. L’α-diversità rappresenta la diversità dell’assemblaggio, calcolata come il numero di specie per campione (ricchezza di specie, S). Infine, la β-diversità rappresenta l’eterogeneità dei popolamenti calcolata come dispersione a livello dei centroidi. La qualità ecologica sarà valutata in aree a differente grado di protezione all’interno dell’isola dell’Asinara, tra 25 e 35 metri di profondità, mediante un disegno di campionamento gerarchizzato, per valutare la risposta dei popolamenti del coralligeno allo stress antropico e confrontata con altre zone del Mediterraneo

Caratterizzazione dei popolamenti associati agli habitat dominati da Eunicella cavolini (Koch, 1887) e Paramuricea clavata (Risso, 1826) dell’Isola del Giglio, Toscana

The present work aimed at assessing the structure of coralligenous assemblages dominated by Eunicella cavolini (Koch, 1887) and Paramuricea clavata (Risso, 1826) in the Tyrrhenian Sea. A standardized non-destructive method was applied through photoquadrat sampling. A hierarchical sampling design was used. A total of 64 species belonging to 9 morphological groups were identified and percentage cover of conspicuous morphological groups was calculated. Results suggests that coralligenous communities dominated by E. cavolini and P. clavata constitute highly diverse habitats and they present several similarities to their counterparts in the Aegean Sea

Effects of Field Simulated Marine Heatwaves on Sedimentary Organic Matter Quantity, Biochemical Composition, and Degradation Rates

Since rising temperature (T) will enhance biochemical reactions and coastal marine sediments are hotspots of carbon cycling, marine heatwaves’ (MHWs’) intensification caused by climate change will affect coastal biogeochemistry. We investigated the effects of MHWs on sediment organic matter (OM) in a nearshore locality (NW Sardinia, Mediterranean Sea) receiving an artificial warm water plume generating T anomalies of 1.5–5.0 °C. Sediments were collected before and after 3 and 11 weeks from the initial plume release. Both MHWs influenced sedimentary OM quantity, composition, and degradation rates, with major effects associated with the highest T anomaly after 3 weeks. Both MHWs enhanced sedimentary OM contents, with larger effects associated with the highest T anomaly. Phytopigment contents increased in the short term but dropped to initial levels after 11 weeks, suggesting the occurrence of thermal adaptation or stress of microphytobenthos. In the longer term we observed a decrease in the nutritional quality of OM and a slowdown of its turnover mediated by extracellular enzymes, suggestive of a decreased ecosystem functioning. We anticipate that intensification of MHWs will affect benthic communities not only through direct effects on species tolerance but also by altering benthic biogeochemistry and the efficiency of energy transfer towards higher trophic levels

Field thermo acclimation increases the resilience of Posidonia oceanica seedlings to marine heat waves

10 pages, 6 tables, 6 figures.-- Under a Creative Commons licenseAcclimation is a response that results from chronic exposure of an individual to a new environment. This study aimed to investigate whether the thermal environment affects the early development of the seagrass Posidonia oceanica, and whether the effects of a field-simulated Marine Heat Wave (MHW) on seedlings change depending on acclimation. The experiment was done in the field using a crossed design of Acclimation (acclimated vs unacclimated) and MHW (present vs absent) factors. Acclimation has initially constrained the development of P. oceanica seedlings, but then it increased their resilience to the MHW, under both a morphological and biochemical (fatty acid saturation) level. This treatment could be considered in P. oceanica restoration projects in a climate change-impaired sea, by purposely inducing an increased resistance to heat before transplantsThis research was financially supported by Botany and Plant Science at NUI Galway, by the project Marine habitats restoration in a climate change-impaired Mediterranean Sea [MAHRES], funded by the Italian Ministry of Research under the PRIN 2017 Program (Project N. 2017MHHWBN; CUP: 74I19001320001) and by PON—National Operational Programme—Research and Innovation 2014–2020—PhDs and research contracts on innovation-related topicsPeer reviewe

Supplementary materials Field thermo acclimation increases the resilience of Posidonia oceanica seedlings to marine heat waves

7 pages. -- File includes 4 tables, 2 figuresTable S1. PERMANOVA results of the effect of site (cold vs warm) on the lipid content (SFA; MUFA; PUFA; PUFA/SFA; C18:3n3/C16:0; n3/n6; %TFA) of T1 plants on both leaves and seeds.-- Table S2. Morphological variables of P. oceanica at T1 and T2. Results are expressed as mean ± SD.-- Table S3. Total fatty acid content and composition in leaves and seeds of P. oceanica at T1. Results are expressed as mean ± SD.-- Table S4. Total fatty acid content and composition in leaves and seeds of P. oceanica at the end of the experiment (T2). Results are expressed as mean ± SD.-- Fig. S1 Location of the two beaches in the North Sardinia (Monti Russu in green and San Silverio in light green) where the seedlings were collected.-- Fig. S2 Boxplots of the morphological variables at T1. Color blue represents the cold site (unacclimated); red the warm site (acclimated)Peer reviewe

Field development of Posidonia oceanica seedlings changes under predicted acidification conditions

11 pages, 7 figures, 2 tablesOcean acidification has been consistently evidenced to have profound and lasting impacts on marine species. Observations have shown seagrasses to be highly susceptible to future increased pCO2 conditions, but the responses of early life stages as seedlings are poorly understood. This study aimed at evaluating how projected Mediterranean Sea acidification affects the survival, morphological and biochemical development of Posidonia oceanica seedlings through a long-term field experiment along a natural low pH gradient. Future ocean conditions seem to constrain the morphological development of seedlings. However, high pCO2 exposures caused an initial increase in the degree of saturation of fatty acids in leaves and then improved the fatty acid adjustment increasing unsaturation levels in leaves (but not in seeds), suggesting a nutritional compound translocation. Results also suggested a P. oceanica structural components remodelling which may counteract the effects of ocean acidification but would not enhance seagrass seedling productivityThis study has been funded by Italian Ministry of Education and Research PRIN 2017 (MHHWBN) “Marine Habitats restoration in a climate change-impaired Mediterranean Sea (MAHRES)” and facilitated by ERASMUS + Traineeship Programme support to A.P. during analysis of data in Botany and Plant Science at the University of Galway. PB-C acknowledges its postdoc fellowship supported by Juan de la Cierva Formacion and funded by Spanish Ministry of Science and Innovation. GC acknowledges the support of NBFC to University of Sassari, funded by the Italian Ministry of University and Research, PNRR, Missione 4, Componente 2, “Dalla ricerca all'impresa”, Investimento 1.4 Project CN00000033Peer reviewe

Animal Forest Mortality: Following the Consequences of a Gorgonian Coral Loss on a Mediterranean Coralligenous Assemblage

In this work, the consequences of a local gorgonian coral mortality on the whole coralligenous assemblage were studied. A Before/After-Control/Impact sampling design was used: the structure of the coralligenous assemblage was compared before and after the gorgonian mortality event at the mortality site and two control sites. At the mortality site, a relevant decrease in alpha and beta diversity occurred, with a shift from a stratified assemblage characterized by gorgonians and other invertebrates to an assemblage dominated by algal turfs; conversely, neither significant variations of the structure nor decrease in biodiversity were observed at the control sites. The assemblage shift involved the main taxa in different times: in autumn 2018, a large proportion of the plexaurid coral Paramuricea clavata died, but no significant changes were observed in the structure of the remaining assemblage. Then, in autumn 2019, algal turfs increased significantly and, one year later, the abundance of the gorgonian Eunicella cavolini and bryozoans collapsed. Although the mechanisms of the assemblage shift following gorgonian loss will remain uncertain and a cause-effect relationship cannot be derived, results suggest the need for detecting signs of gorgonian forests stress in monitoring programs, which should be considered early indicators of their condition. in the coralligenous monitoring programs for detecting any sign of gorgonian forests stress which should be considered an early indicator of the assemblage condition