Biology subjects

Valsecchi, E.

Publications and source records attributed to Valsecchi, E..

7 recordsLinked to original sources

bioRxiv2026

World Wide Eyes: Social Media-Assisted Wildlife Research. Assessing Supplementary Feeding Areas for Eastern Australian Humpback Whales as a Case Study.

Humpback whales typically adopt a "feast-and-famine" strategy, feeding intensively at high-latitude summer feeding grounds while fasting throughout migration. However, increasing reports of feeding at mid-latitudes suggest that some individuals may supplement their energetic requirements along migratory corridors. Detecting and monitoring these emerging behaviours remains challenging because conventional marine mammal surveys are often spatially and financially constrained. Here, we used passive citizen science by systematically compiling humpback whale feeding records from publicly shared Facebook and Instagram posts and the citizen-science platform Happywhale to investigate feeding events of the Eastern Australian population over five consecutive migration seasons (2020-2024). A total of 256 feeding records were collected, revealing three recurrent candidate Supplementary Feeding Areas (SFAs): the Sapphire Coast (New South Wales), Port Phillip and Bass Strait (Victoria), and southeast Tasmania. Feeding events occurred across multiple migratory months, involved both solitary whales and groups, and included both krill and schooling fish as prey, with lunge feeding representing the predominant feeding strategy. Comparison of passive and active citizen-science sources showed that social-media records substantially increased the number of documented feeding events and more frequently allowed feeding behaviour to be identified. The temporal recurrence of feeding events across five consecutive migration seasons supports the hypothesis that some behaviours traditionally interpreted as opportunistic feeding may instead represent recurrent supplementary feeding. Overall, this study demonstrates the value of passive citizen science as a cost-effective complement to conventional monitoring programmes for detecting large-scale behavioural changes and identifying candidate supplementary feeding areas in migratory humpback whales.

ecology↗

bioRxiv2023

Environmental DNA reveals fine scale spatial and temporal variation of prey species for marine mammals in a Scottish marine protected area

Marine mammal foraging grounds are popular focal points for marine protected area (MPA) implementation, but may be temporally dynamic, requiring continuous monitoring to infer prey availability and abundance. Marine mammal distributions are assumed to be driven by their prey in foraging areas, but limited understanding of prey distributions often prevents us from exploring how shifting prey availability impacts both seasonal and long-term marine mammal distributions. Environmental DNA (eDNA) metabarcoding could enhance understanding of marine mammal habitat use in relation to their prey through simultaneous monitoring of both. However, eDNA applications focused on marine mammals or predator-prey dynamics have been limited to date. In this study, we assess spatiotemporal changes in the availability and abundance of minke whale (Balaenoptera acutorostrata) prey species in a newly established MPA, employing eDNA metabarcoding. We recovered 105 molecular operational taxonomic units (OTUs) from marine vertebrates using two primer sets targeting 12S and 16S genes, along with 112 OTUs from a broader eukaryotic primer set targeting 18S rRNA. Overall, key forage fish prey species, sandeels and clupeids, were the most abundant teleost fishes detected, although their availability varied temporally and with distance from shore. We also found clear spatial partitioning between coastal bottlenose dolphins and the more pelagic minke whales and harbour porpoises, paralleling availability of their main prey species. Other species of conservation interest were also detected including the critically endangered European eel (Anguilla anguilla), blue fin tuna (Thunnus thynnus), and the invasive pink salmon (Oncorhynchus gorbuscha). This study demonstrates the application of eDNA to detect spatiotemporal trends in the occurrence and abundance of cetacean predators and their prey, furthering our understanding of fine-scale habitat use within MPAs. Future, long-term monitoring of predator-prey dynamics with eDNA could improve our ability to predict climate-induced shifts in foraging grounds and enhance rapid responses with appropriate management actions.

ecology↗

bioRxiv2023

Surface-sourced eDNA to track deep-diver cetaceans: the study case of Cuvier's beaked whale (Ziphius cavirostris) at Caprera Canyon and surrounding areas (Western Mediterranean Sea)

Among cetaceans, the Cuviers beaked whale is considered an extreme diver, very challenging to be studied with standard monitoring methods due to its elusive behaviour and a preference for deep offshore waters. These limitations seem to be mitigated by the use of new molecular methodologies capable of intercepting small traces of DNA left in the environment (eDNA) by marine organisms. Moreover, the collection of water from the superficial layer of the sea represents a perfect case study for the targeting of marine mammals, as the constraints imposed by their nature implies periodic and frequent surfacing. Therefore, we designed and tested a taxon-specific primer set to infer the Cuviers beaked whale presence, with the aims of 1) examining the effectiveness of the eDNA technique to detect the presence of deep-diving cetacean in open waters, using the Cuviers beaked whale as case study; 2) providing data on the spatiotemporal occurrence of this species within the Canyon of Caprera; and 3) assessing the species occurrence in central northern Mediterranean Sea based on molecular traces. Results from this study demonstrated that collection of superficial waters is a valid approach to monitor deep-diving cetacean species, without the need for complementary visual survey monitoring. Specifically, this study provides evidence of the regular presence of the Cuviers beaked whale in the Canyon of Caprera, with a preference for bathymetry in the range of 700-1000 m. This study also showed a potential inshore movement of this species during fall, which is possibly related to migration of its cephalopod prey or a shift in prey preferences. Overall, the data presented here are particularly relevant in the optic of proposing the Caprera Canyon as an Important Marine Mammal Area (IMMA) in the Mediterranean Sea. At a wider level, this study also showed that the stronger positive signals were recorded in sampling stations located on submarine canyon systems, demonstrating the importance of these areas as elective habitats for the Cuviers beaked whale, thus the pivotal priority to their conservation.

ecology↗

bioRxiv2022

Sampling from commercial vessel routes can capture marine biodiversity distributions effectively

Collecting fine-scale occurrence data for marine species across large spatial scales is logistically challenging, but is important to determine species distributions and for conservation planning. Inaccurate descriptions of species ranges could result in designating protected areas with inappropriate locations or boundaries. Optimising sampling strategies therefore is a priority for scaling up survey approaches using tools such as environmental DNA (eDNA) to capture species distributions. eDNA can detect diverse taxa simultaneously, but to date has rarely been applied across large spatial scales relevant for conservation planning. In a marine context, commercial vessels, such as ferries, could provide sampling platforms allowing access to under-sampled areas and repeatable sampling over time to track community changes. However, sample collection from commercial vessels could be biased and may not represent biological and environmental variability. Here, we evaluate whether sampling along Mediterranean ferry routes can yield unbiased biodiversity survey outcomes, based on perfect knowledge from a stacked species distribution model (SSDM) of marine megafauna. Simulations were carried out representing different sampling strategies (random vs systematic), frames (ferry routes vs unconstrained) and number of sampling points. SSDMs were remade from different sampling simulations and compared to the perfect knowledge SSDM to quantify the bias associated with different sampling strategies. Ferry routes detected more species and were able to recover known patterns in species richness at smaller sample sizes better than unconstrained sampling points. However, to minimise potential bias, ferry routes should be chosen to cover the variability in species composition and its environmental predictors in the SSDMs. The workflow presented here can be used to design effective eDNA sampling strategies using commercial vessel routes globally. This approach has potential to provide a cost-effective method to access remote oceanic areas on a regular basis, and can recover meaningful data on spatiotemporal biodiversity patterns.

ecology↗

bioRxiv2021

Ferries and environmental DNA: underway sampling from commercial vessels provides new opportunities for systematic genetic surveys of marine biodiversity

Marine environmental DNA (eDNA) is an important tool for biodiversity research and monitoring but challenges remain in scaling surveys over large spatial areas, and increasing the frequency of sampling in remote locations at reasonable cost. Here we demonstrate the feasibility of sampling from commercial vessels (Mediterranean ferries) while underway, as a strategy to facilitate replicable, systematic marine eDNA surveys in locations that would normally be challenging and expensive for researchers to access. Sixteen eDNA samples were collected from 4 fixed sampling stations, and in response to 4 cetacean sightings, across three cruises undertaken along the 300 km ferry route between Livorno (Tuscany) and Golfo Aranci (Sardinia) in the Ligurian/Tyrrhenian Seas, June-July 2018. Using 12SrDNA and 16SrDNA metabarcoding markers, we recovered diverse marine vertebrate Molecular Operational Taxonomic Units (MOTUs) from teleost fish, elasmobranchs, and cetaceans. We detected sample heterogeneity consistent with previously known variation in species occurrences, including putative species spawning peaks associated with specific sea surface temperature ranges, and increased night time abundance of bathypelagic species known to undertake diel migrations through the water column. We suggest commercial vessel based marine eDNA sampling using the global shipping network has potential to facilitate broad-scale biodiversity monitoring in the worlds oceans.

molecular biology↗

bioRxiv2021

Newly developed ad hoc molecular assays shows how eDNA can witness and anticipate the monk seal recolonization of central Mediterranean

The monk seal Monachus monachus is the most endangered pinniped worldwide and the only one found in the Mediterranean, where its distribution and abundance have suffered a drastic decline in the last few decades. Data on its status are scattered due to both its rarity and evasiveness, and records are biased towards occasional, mostly coastal, encounters. Nowadays molecular techniques allow us to detect and quantify minute amounts of DNA traces released in the environment (eDNA) by any organism. We present three qPCR-assays targeting the monk seal mitogenome. The assays were soundly tested on an extensive and diversified sample set (n=73), including positive controls from Madeira breeding population collected during the peak of abundance, and two opportunistic Mediterranean eDNA-sample collections (offshore/coastal) from on-going projects. Monk seal DNA was detected in 47.2% and 66.7% of the samples collected in the Tyrrhenian from a ferry platform (2018-2019) and in the Pelagie archipelago -Strait of Sicily- (2020) respectively, anticipating (up to 2 year) visual observations occurred subsequently in proximity of the sampled areas. In the Tyrrhenian, detection occurrence increased between 2018 and 2019. Monk seal DNA recoveries were commoner in night-time ferry-samples, suggesting nocturnal predatory activity in pelagic waters. The proposed technique provides a non-invasive and yet highly-sensitive tool for defining the monk seal actual distribution and home range, its recovery rate and pinpoint coastal/offshore localities where prioritizing conservation, research, citizen science and education initiatives.

molecular biology↗

bioRxiv2019

Novel Universal Primers For Metabarcoding eDNA Surveys Of Marine Mammals And Other Marine Vertebrates

Metabarcoding studies using environmental DNA (eDNA) and high throughput sequencing (HTS) are rapidly becoming an important tool for assessing and monitoring marine biodiversity, detecting invasive species, and supporting basic ecological research. Several barcode loci targeting teleost fish and elasmobranchs have previously been developed, but to date primer sets focusing on other marine megafauna, such as marine mammals have received less attention. Similarly, there have been few attempts to identify potentially universal barcode loci which may be informative across multiple marine vertebrate Orders. Here we describe the design and validation of four new sets of primers targeting hypervariable regions of the vertebrate mitochondrial 12S and 16S rRNA genes, which have conserved priming sites across virtually all cetaceans, pinnipeds, elasmobranchs, boney fish, sea turtles and birds, and amplify fragments with consistently high levels of taxonomically diagnostic sequence variation. In silico validation using the OBITOOLS software showed our new barcode loci outperformed most existing vertebrate barcode loci for taxon detection and resolution. We also evaluated sequence diversity and taxonomic resolution of the new barcode loci in 680 complete marine mammal mitochondrial genomes demonstrating that they are effective at resolving amplicons for most taxa to the species level. Finally, we evaluated the performance of the primer sets with eDNA samples from aquarium communities with known species composition. These new primers will potentially allow surveys of complete marine vertebrate communities in single HTS metabarcoding assessments, simplifying workflows, reducing costs, and increasing accessibility to a wider range of investigators.

ecology↗