1,721,049 research outputs found
What do marine zoologists need from an underwater vehicle?
No full textFuture perspectives in underwater vehicles potential uses and needed features are here presented and discussed through different study cases embracing research, monitoring and exploration, from shallow-water to deep-sea habitats and communities. Essential features asked to the next generation of underwater vehicles include the possibilities to explore deeper depths, observe in detail targeted specimens, use further spectra besides the visible, sample soft-body benthic organisms, move within demanding situations (e.g. obstacles on the seabed), as well as the ability to stably stop on the seabed and collect images in a relative long (e.g. few hours) time spam
Biometric relationships in the red sea pen Pennatula rubra (Cnidaria: Pennatulacea)
Full text linkColonies of the red sea pen Pennatula rubra sampled by trawling in the northwestern Mediterranean Sea were analyzed. Biometric parameters such as total length, rachis length, number of polyp leaves, wet weight and dry weight were measured and related to each other by means of regression analysis. The most reliable measures for future inferencing of colonies size and biomass through visual techniques were individuated in order to allow a noninvasive study of P. rubra population structure and dynamics
DNA barcoding unveiling rare species: the case of Pruvotfolia pselliotes (Labbé, 1923) (Mollusca: Gastropoda: Nudibranchia) in the Mediterranean Sea
Full text linkThe Mediterranean Sea is a hot spot for marine biodiversity, and this is particularly evident taking into consideration the diversity observed in many animal groups, among them the Molluscs. In the last decade, several works have revealed a high rate of cryptic diversity characterizing the Molluscan fauna of the Mediterranean Sea and an increasing number of endemic and/or new species inhabiting this semi-enclosed basin have been recorded or described. The DNA-barcoding method is considered an essential step in the integrative taxonomy applications, to unravel cryptic diversity and for species identification. Here we report the case of DNA-barcoding technique applied to identify a nudibranch (Heterobranchia) collected from the Adriatic Sea, in the Bay of Kotor (Montenegro), for which a standard morphological identification was not possible. Mediterranean specimen belonging to Pruvotfolia pselliotes (Labbé, 1923) is for the first time molecularly identified and its COI DNA sequence compared with the one of an individual collected from the type locality. In addition, this is the first verified report of this species from the Adriatic Sea. Finally, the potential of using DNA-barcoding is here discussed, together with the habitat and the geographical distribution of this uncommon species
A sea of corals in the Mediterranean Sea
No full textThe fortuitous discovery of living colonies of white corals on the unexplored bottoms of Santa Maria di Leuca (Ionian Sea), 18 years ago, represented an unprecedented turning point in the study of the Mediterranean bathyal ecosystems. A long-term explorative and descriptive study program was carried out in this area, also stimulating the search of coral forest ecosystems all over the basin, at all depths, and the carrying out of numerous relevant scientific studies. The deep coral era has started. Nowadays, considering as cold-water corals the habitat-forming azooxanthellate cnidarians, 61 deep coral sites are known in the basin
Habitat, morphology and trophism of Tritonia callogorgiae sp. nov., a large nudibranch inhabiting Callogorgia verticillata forests in the Mediterranean Sea
Full text linkThe continuing exploration of the Mediterranean deep sea reveals that a complete census of the biodiversity of one of the most studied marine areas in the world is yet to be fully accomplished. A tritoniid nudibranch new to science is described upon material recovered off the Montenegro margin, Adriatic Sea, associated with the alcyonacean Primnoidae Callogorgia verticillata (Pallas, 1766). Here, a coral forest dominated by C. verticillata, together with other alcyonaceans, antipatharians and scleractinians, represents the habitat of the new species. As documented by Remotely Operated Vehicle (ROV) observations, the coral forest covers an area of 600 m2 at 420–426 m depth, with dense growth of C. verticillata colonies (1.34 ± 0.08 colonies m−2). As many as 66 nudibranch specimens have been observed on C. verticillata. Tritonia callogorgiae sp. nov. (Gastropoda, Nudibranchia, Tritoniidae) is up to 12 cm long, yellow to orange/reddish in colour with white papillae all over the body. It has a velum with six appendages (three per side), and 4–5 pairs of dichotomous gills. Internally, the species is distinguished from other tritoniids for the absence of stomach plates and a distinctive radula with formula 50 × 110.1.1.1.108. It represents the first case of Tritonia species living in the deep Mediterranean Sea and the only one associated to C. verticillata. Stomach content documents that Tritonia callogorgiae sp. nov. feeds on C. verticillata. Further visual ROV records from other sectors of the Mediterranean Sea indicate that the distribution of this new described species is almost basin-wide. The discovery of another undescribed member of the benthic megafauna related to deep-sea coral grounds further highlights the need for conservation of such habitats
Distribution and swimming ability of the deep-sea holothuroid Penilpidia ludwigi (Holothuroidea: Elasipodida: Elpidiidae)
No full textThe deep-sea elpidiid holothuroid, Penilpidia ludwigi, was recorded using a Remotely Operated Vehicle in the Western, Central, and Eastern Mediterranean Sea. This species, endemic to the basin, was previously captured above the seabed in sediment traps and based on these records its swimming ability was assumed. The present study reports the first in situ observations of swimming P. ludwigi and provides an update on the geographic and bathymetric distribution of this species. A large aggregation of thousands of specimens was observed in the Levantine Sea with a maximum local density 300 ind. m(-2). The ROV surveys allowed observation of the behavior of the species and description of its mode of swimming. Active swimming using strokes of the tentacle crown is combined with drifting benefiting of the current, the former used for fast escape the latter mainly for energy-saving displacement. Swimming behavior allows P. ludwigi to exploit various deep-sea habitats including seamounts, canyons, and ridges inaccessible to non-swimming deposit feeders
A minimal metric for the characterization of acoustic noise emitted by underwater vehicles
Full text linkUnderwater robots emit sound during operations which can deteriorate the quality of acoustic data recorded by on-board sensors or disturb marine fauna during in vivo observations. Notwithstanding this, there have only been a few attempts at characterizing the acoustic emissions of underwater robots in the literature, and the datasheets of commercially available devices do not report information on this topic. This work has a twofold goal. First, we identified a setup consisting of a camera directly mounted on the robot structure to acquire the acoustic data and two indicators (i.e., spectral roll-off point and noise introduced to the environment) to provide a simple and intuitive characterization of the acoustic emissions of underwater robots carrying out specific maneuvers in specific environments. Second, we performed the proposed analysis on three underwater robots belonging to the classes of remotely operated vehicles and underwater legged robots. Our results showed how the legged device produced a clearly different signature compared to remotely operated vehicles which can be an advantage in operations that require low acoustic disturbance. Finally, we argue that the proposed indicators, obtained through a standardized procedure, may be a useful addition to datasheets of existing underwater robots
The Ketogenic Diet Improves Gut–Brain Axis in a Rat Model of Irritable Bowel Syndrome: Impact on 5-HT and BDNF Systems
Full text linkAltered gut–brain communication can contribute to intestinal dysfunctions in the intestinal bowel syndrome. The neuroprotective high-fat, adequate-protein, low-carbohydrate ketogenic diet (KD) modulates the levels of different neurotransmitters and neurotrophins. The aim was to evaluate the effects of KD on levels of 5-HT, the receptors 5-HT3B and 5-HT4, the 5-HT transporter SERT, the neurotrophin BDNF, and its receptor TrkB in the colon and brain of a rat model of irritable bowel syndrome (IBS). Samples from Wistar rats exposed to maternal deprivation as newborns and then fed with a standard diet (IBS-Std) or KD (IBS-KD) for ten weeks were analyzed. As controls, unexposed rats (Ctrl-Std and Ctrl-KD) were studied. IBS-Std rats had a disordered enteric serotoninergic signaling shown by increased mucosal 5-HT content and reduced SERT, 5-HT3B, and 5-HT4 levels compared to controls. In the brain, these animals showed up-regulation of the BDNF receptor TrkB as a counteracting response to the stress-induced reduction of the neurotrophin. KD showed a dual effect in improving the altered 5-HT and BDNF systems. It down-regulated the increased mucosal 5-HT without affecting transporter and receptor levels. KD improved brain BDNF levels and established negative feedback, leading to a compensatory downregulation of TrkB to maintain a physiological steady state
The Millepora Zone Is Back: Recent Findings from the Northernmost Region of the Maldives
No full textThree species of the tropical hydrocoral genus Millepora were common and abundant in the Maldives before 1998, characterizing extensive shallow reef areas known as ‘Millepora zones’. The 1998 heat wave resulted in mass mortality of all the Millepora species, the characteristic Millepora zones disappeared, and only a few observations of isolated colonies were reported in the years ahead. A recent expedition (January 2024) to the northernmost region of the Maldives (Ihavandhippolhu Atoll) revealed new Millepora zones at 7–13 m depth, suggesting a potential repopulation of a vulnerable genus considered regionally extinct
The new face of the northernmost coral reefs of the Maldives revisited after 13 years
No full textCoral reef ecosystems in Ihavandhippolhu Atoll, the northernmost atoll of the Maldives, have undergone significant changes following the 1998, 2010, and 2016 bleaching events. This study evaluates the recovery after 13 years following repeated bleaching events and the shift in coral reef composition in this remote and scantly explored region of the Indian Ocean. Data collected in January 2024 from ten strategic sites within the atoll reveal substantial shifts in benthic composition compared to earlier surveys from 2011. We observed a significant increase in overall hard coral cover, with resilient taxa-such as massive and encrusting corals-becoming dominant after bleaching events. In contrast, more sensitive genera like branching and tabular Acropora have declined sharply, indicating a shift in the benthic community composition toward more resistant coral taxa. The substantial recovery of hard coral cover over time suggests the resilience of the coral ecosystem in this remote atoll, although the recovery process is still ongoing, as shown by the incomplete restoration of original diversity and colony growth forms. A standardized and periodic monitoring plan in Ihavandhippolhu Atoll will be needed to track the ongoing changes in reef community composition under conditions of minimal human influence
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