Assessing population collapse of Drupella spp. (Mollusca: Gastropoda) 2 years after a coral bleaching event in the Republic of Maldives

AbstractCorallivory causes considerable damage to coral reefs and can exacerbate other disturbances. Among coral predators, Drupella spp. are considered as delayer of coral recovery in the Republic of Maldives, although little information is available on their ecology. Thus, we aimed to assess their population structure, feeding behaviour and spatial distribution around 2 years after a coral bleaching event in 2016. Biological and environmental data were collected using belt and line intercept transects in six shallow reefs in Maldives. The snails occurred in aggregations with a maximum of 62 individuals and exhibited a preference for branching corals. Yet, the gastropods showed a high plasticity in adapting feeding preferences to prey availability. Drupella spp. were homogenously distributed in the study area with an average of 9.04 ± 19.72 ind/200 m2. However, their occurrence was significantly different at the reef scale with the highest densities found in locations with higher coral cover. The impact of Drupella spp. appeared to be minimal with the population suffering from the loss of coral cover. We suggest that monitoring programs collect temporal- and spatial-scale data on non-outbreaking populations or non-aggregating populations to understand the dynamics of predation related to the co-occurrence of anthropogenic and natural impacts

Molecular and biological evidence for a severe seedling yellows strain of Citrus tristeza virus spreading in southern Italy

Citrus tristeza virus (CTV) outbreaks have been reported in the main citrus-growing regions of Italy in the past 10 years. In some areas where eradication efforts failed to suppress spread, high CTV incidence is now observed. Recently, potentially severe CTV strains were detected in Calabria (southern Italy), one of the major citrus-growing area. As a result, investigations of the virulence and molecular features of CTV populations spreading in this region were undertaken. Virus was detected by enzyme-linked immunosorbent assay (ELISA) using a broad spectrum polyclonal antiserum, and was differentiated into potential virulent categories with the severe-strain discriminating monoclonal antibody MCA13. Isolate genotyping was conducted using reverse-transcription polymerase chain reaction (RT-PCR) with multiple molecular markers (MMM), single-strand conformation polymorphism (SSCP) analysis of the amplicons from the genes coding for the coat protein (CP) p25 and the non-structural p20 protein as well as sequence analysis. Based on the serological reactivity, the isolates were differentiated in two distinct serogroups: MCA13-reactive and MCA13 non-reactive. Similarly, based on the molecular profile, the isolates were grouped in two genetically distinct phylogenetic clusters, and associated either with a T30-like or with a T3-like genotype. These data were related to the results of biological indexing on standard indicator plants, which distinguished isolates causing mild or severe seedling yellow reactions. The study has demonstrated the presence of MCA13-reactive isolates associated with a T3-like genotype and causing severe seedling yellows in sour orange, grapefruit and lemon seedlings, and stem pitting in Mexican lime

Effects of the COVID-19 lockdowns on the management of coral restoration projects

Coral restoration initiatives are gaining significant momentum in a global effort to enhance the recovery of degraded coral reefs. However, the implementation and upkeep of coral nurseries are particularly demanding, so that unforeseen breaks in maintenance operations might jeopardize well-established projects. In the last 2 years, the COVID-19 pandemic has resulted in a temporary yet prolonged abandonment of several coral gardening infrastructures worldwide, including remote localities. Here we provide a first assessment of the potential impacts of monitoring and maintenance breakdown in a suite of coral restoration projects (based on floating rope nurseries) in Colombia, Seychelles, and Maldives. Our study comprises nine nurseries from six locations, hosting a total of 3,554 fragments belonging to three coral genera, that were left unsupervised for a period spanning from 29 to 61 weeks. Floating nursery structures experienced various levels of damage, and total fragment survival spanned from 40 to 95% among projects, with Pocillopora showing the highest survival rate in all locations present. Overall, our study shows that, under certain conditions, abandoned coral nurseries can remain functional for several months without suffering critical failure from biofouling and hydrodynamism. Still, even where gardening infrastructures were only marginally affected, the unavoidable interruptions in data collection have slowed down ongoing project progress, diminishing previous investments and reducing future funding opportunities. These results highlight the need to increase the resilience and self-sufficiency of coral restoration projects, so that the next global lockdown will not further shrink the increasing efforts to prevent coral reefs from disappearing.Peer reviewe

ClimateFish: A Collaborative Database to Track the Abundance of Selected Coastal Fish Species as Candidate Indicators of Climate Change in the Mediterranean Sea

Under the effects of global warming, many animals and plants are undergoing rapid distribution shifts. These changes can be particularly rapid in marine fishes, and many species have responded markedly to recent increases in sea temperature. ClimateFish is an open-access database, which collates abundance data for 7 Mediterranean indigenous and 8 non-indigenous fishes, proposed as candidate indicators of climate change. These species have been selected by a network of Mediterranean scientists based on their wide distribution, responsiveness to temperature conditions and easy identification. Data are periodically collected according to a standard visual census protocol in four different depth layers. At present, the database collates data on a total number of 101'771 observed individuals belonging to the 15 target species. Counts were realized along 3142 transects carried out in 7 Mediterranean countries between 2009 and 2021. This database, associated with climate data, offers new opportunities to investigate spatiotemporal effects of climate change and to test the effectiveness of each selected indicator. Data are available at https://doi.org/10.17882/86784.The Mediterranean ClimateFish initiative was initially conceived by the international basin wide monitoring program CIESM Tropical Signals (funded by the Albert II of Monaco Foundation) and subsequently supported by the Interreg Med Programme (Projects: MPA-ADAPT, grant number 1MED15_3.2_M2_337 and MPA Engage, grant number 5MED18_3.2_M23_007), 85% co funded by the European Regional Development Fund

Monitoraggio di specie marine sensibili ai cambiamenti climatici nel Golfo della Spezia

I dati raccolti dagli ambienti marini costieri e profondi del Mar Mediterraneo rivelano la tendenza a un aumento della temperatura, della frequenza degli eventi estremi, delle mortalità di massa e dell’arrivo di specie aliene. Gli effetti dei cambiamenti climatici sugli organismi marini si manifestano attraverso modifiche nell’abbondanza e nella distribuzione geografica di determinate specie. La Tesi si inserisce nell’ambito del progetto “Tropical Signals Program: monitoring macrodescriptor species of climate warming” (TS) della Commission Internationale pour l'Exploration Scientifique de la Mer Méditerranée (CIESM), il cui obiettivo è quello di valutare in ambiente marino gli effetti dei cambiamenti climatici a breve e a lungo termine su scala mediterranea utilizzando una serie di specie animali e vegetali quali macrodescrittori. L’obiettivo del lavoro di Tesi è stato quello di monitorare l’ambiente marino nell’area del Golfo della Spezia al fine di rilevare la presenza/assenza, le variazioni in abbondanza e la distribuzione delle specie selezionate come macrodescrittori dalla CIESM. La raccolta dei dati è avvenuta, attenendosi ai protocolli redatti dal progetto TS, seguendo due modalità. La prima ha previsto attività di monitoraggio della fascia di profondità 0-3 m tramite snorkeling, ed è stata effettuata in due date estive nel 2012 e due nel 2013, in tre località della costa spezzina e lungo due transetti per località, per il monitoraggio del benthos e quattro transetti per località per il censimento dei pesci. La seconda ha riguardato la raccolta di informazioni relative ai cambiamenti nella fauna ittica locale degli ultimi decenni, tramite interviste a pescatori sportivi e professionisti operanti nel Golfo della Spezia. I risultati dei monitoraggi hanno evidenziato la presenza nell’area di studio di alcuni macrodescrittori ad affinità calda comuni nel Mediterraneo, quali il briozoo Zoobotryon verticillatum (delle Chiaje, 1822), il mollusco Stramonita haemastoma (Linnaeus, 1767), il teleosteo Thalassoma pavo (Linnaeus, 1758), ed un altro ad affinità fredda quale l’echinoderma Marthasterias glacialis (Linnaeus, 1758). Non sono stati invece osservati i due teleostei invasivi Siganus luridus (Rüppell, 1829) e Siganus rivulatus (Forsskål, 1775), avvallando così l’ipotesi della loro assenza nel Mar Ligure orientale. Tra i risultati più interessanti emersi dalle interviste ai pescatori vi è il costante aumento nell’ultimo decennio delle catture del teleosteo ad affinità calda Pomatomus saltatrix (Linnaeus, 1766), dovuto probabilmente alle condizioni di temperatura più favorevoli. I dati raccolti con lo snorkeling fanno parte di un’analisi a breve termine delle condizioni dell’ambiente marino all’interno dell’area di studio e rappresentano un pool di informazioni che andranno a contribuire agli studi a lungo termine del progetto TS. Attraverso le interviste ai pescatori è stata effettuata una prima esperienza di raccolta dati nell’area spezzina nell’ambito della “Citizen Science”, un tipo di monitoraggio che sfrutta le conoscenze accumulate nei decenni dai pescatori della zona su risorse che non sono state monitorate scientificamente con continuità. Anche questi dati forniranno un punto di inizio per ulteriori approfondimenti nell’ambito del progetto TS

A new method for the transplanting of the seagrass Posidonia oceanica

The fast decline of coastal habitats happening worldwide is pushing for active restoration measures to mitigate the effects of anthropogenic impacts. In the Mediterranean Sea, meadows of the endemic seagrass Posidonia oceanica are declining mostly due to human activities carried out along the coast. Given the high conservation value of this habitat, several transplanting efforts have been attempted in the last decades to slow down this general decline and enhance the recovery of stressed meadows. In this study, we applied a new technique to transplant P. oceanica based on 100% natural materials. The study was carried out at the Tremiti Islands Marine Protected Area (Adriatic Sea), where 100 m(2) of meadow were transplanted. We used drifting cuttings, already uprooted by tourists' anchors, as donor material. These were transplanted on organic mats made of coconut fibers, subsequently stabilized with local boulders and gravels. The preliminary success was assessed with a two- month monitoring based on visual techniques. The photographic monitoring protocol was set up in order to be accessible for divers and citizen scientists, as well as to avoid any direct impact on the cuttings. Our preliminary results showed promising transplanting success in terms of mats' integrity and cutting coverage (%). Further monitoring will be carried out to evaluate the success over a longer time span and to assess the feasibility of this restoration method at a larger scale

Monitoring and assessing a 2-year outbreak of the corallivorous seastar Acanthaster planci in Ari Atoll, Republic of Maldives

Outbreaks of the corallivorous crown-of-thorns seastars have received increasing attention due to their negative impacts on coral reefs in the Indo-Pacific Ocean. However, outbreaks in remote and dislocated islands are still poorly understood. This study aims to begin filling informational gaps regarding outbreaks of Acanthaster planci in the remote islands of the central Ari Atoll, Republic of Maldives. The population of A. planci was monitored during three periods over 2 years (2015-2016) to evaluate variations in abundance and to characterise size structure and feeding behaviour. The outbreak appeared to be severe and active throughout the entire study period. The size structure analysis revealed a multimodal distribution dominated by individuals between 20 and 30 cm, suggesting that the outbreak may have resulted from a few nearby mass spawning events. Additionally, the most abundant live coral was Porites, which was also the most consumed genus; however, the electivity index showed a preference for corals of the genera Favites and Pavona. Finally, we also highlighted the need for more geographically extended surveys to better understand local patterns regarding outbreaks of A. planci in the Republic of Maldives.JRC.D.1-Bio-econom

Molecular and biological evidence for a severe seedling yellows strain of Citrus tristeza virus spreading in Calabria (Southern Italy)

Citrus tristeza virus (CTV) outbreaks have been reported in the main citrus-growing regions of Italy in the past 10 years. In some areas where eradication efforts failed to suppress spread, high CTV incidence is now observed. Recently, potentially severe CTV strains were detected in Calabria (southern Italy), one of the major citrusgrowing area. As a result, investigations of the virulence and molecular features of CTV populations spreading in this region were undertaken. Virus was detected by enzyme-linked immunosorbent assay (ELISA) using a broad spectrum polyclonal antiserum, and was differentiated into potential virulent categories with the severe-strain discriminating monoclonal antibody MCA13. Isolate genotyping was conducted using reverse-transcription polymerase chain reaction (RT-PCR) with multiple molecular markers (MMM), single-strand conformation polymorphism (SSCP) analysis of the amplicons from the genes coding for the coat protein (CP) p25 and the non-structural p20 protein as well as sequence analysis. Based on the serological reactivity, the isolates were differentiated in two distinct serogroups: MCA13-reactive and MCA13 non-reactive. Similarly, based on the molecular profile, the isolates were grouped in two genetically distinct phylogenetic clusters, and associated either with a T30-like or with a T3-like genotype. These data were related to the results of biological indexing on standard indicator plants, which distinguished isolates causing mild or severe seedling yellow reactions. The study has demonstrated the presence of MCA13-reactive isolates associated with a T3-like genotype and causing severe seedling yellows in sour orange, grapefruit and lemon seedlings, and stem pitting in Mexican lime