Large-Scale Distribution of the European Seahorses (Hippocampus Rafinesque, 1810): A Systematic Review

Human pressures on marine ecosystems have caused extensive degradation of marine habitats and several local extinctions. Overexploitation and destructive fishing practices are responsible for biodiversity loss in many coastal ecosystems. The definition of conservation programs in marine fish requires comprehensive knowledge on large-scale geographical distribution, while considering distribution/abundance patterns in relation to key environmental variables. Due to their life-cycle traits, the two European seahorses (Hippocampus guttulatus and H. hippocampus), as with other congeneric species, are particularly sensitive to the effects of anthropogenic activities and habitat changes. However, information on the ecological distribution of these two species is scattered, patchy, and mainly focused on small-scale studies. In this paper, we followed an international standard protocol for systematic reviews (the PRISMA protocol) to provide a detailed assessment of the two species’ geographical distribution in relation to the environmental characteristics. According to the 134 analyzed studies, Hippocampus guttulatus is more common in confined areas, while H. hippocampus is found in marine shelf waters. With several interspecific differences, seagrasses were the most used holdfasts of both species. The EUNIS codes (European nature information system) referring to a specific and unique habitat were discussed as a potential tool for defining the ecological distribution of the two species. The obtained results and their future implementation could help plan conservation actions

The effects of post-pasture woody plant colonization on soil and aboveground litter carbon and nitrogen along a bioclimatic transect.

We investigated the effects of woody plant colonization of abandoned pastures on soil and litter organic carbon (C) stocks and nitrogen (N) content along a bioclimatic transect in a semi-arid environment (Sicily, Italy). Soil samples were taken in three successional stages (grazed pasture, shrubland, forest) within each of three bioclimates (supramediterranean - \u201csupra\u201d, mesomediterranean - \u201cmeso\u201d, thermomediterranean - \u201cthermo\u201d). Organic C and N in litter and soil (0-10 cm and 10-30 cm depth) were determined, as well as soil bulk density. Especially at 0-10 cm depth, changes in C and N contents along successional stages differed among bioclimates. Soil organic carbon (SOC) stock decreased from pasture to shrubland and increased from shrubland to forest in \u201csupra\u201d, increased from pasture to shrubland and then remained stable in \u201cthermo\u201d, and was stable in \u201cmeso\u201d. Soil C/N ratio decreased with succession in \u201csupra\u201d, showed no significant trend in \u201cmeso\u201d, and increased with succession in \u201cthermo\u201d. Litter C stock increased with succession in \u201cmeso\u201d, increased from pasture to shrubland and decreased from shrubland to forest in \u201cthermo\u201d, and increased from pasture to shrubland and then remained stable in \u201csupra\u201d. Litter C/N ratio increased in \u201cthermo\u201d and \u201csupra\u201d from pasture to shrubland and from shrubland to forest, but did not change significantly with succession in \u201cmeso\u201d. The different trends in SOC among bioclimates may be caused by changes in the importance of litter input, litter decay rate and mineralization. Successional changes in \u201cmeso\u201d and \u201csupra\u201d appeared to be most affected by litter quality, while those in \u201cthermo\u201d appeared to be strongly influenced by limited litter decay due to low soil moisture and high temperature

Site fidelity of Hippocampus guttulatus Cuvier, 1829 at Mar Piccolo of Taranto (Southern Italy; Ionian Sea)

Lack of detailed knowledge on ecological niche, life cycles, spatial distribution, reproductive biology and space use strongly affects the selection of useful tools and measures in the conservation of threatened marine species. Especially for sedentary and slow species, behaviour and movement capacities are supposed to be the most important functional traits. Indeed, behavioural variability concerning available space and the close presence of individuals is considered a crucial trait for the population dynamics assessments, especially when disturbances of various causes are present in the environment. The present study aimed to investigate the site fidelity and degree of movement of Hippocampus guttulatus, an emblematic and threatened Mediterranean seahorse species. With this aim, a number of seahorses were tagged and monitored throughout two years within a limited area of the lagoon of Mar Piccolo of Taranto (Southern Italy). The studied individuals were initially morphometrically measured for size, sex and life-cycle stage and subsequently monitored through repeated four-month surveys each year. Obtained results indicated high site fidelity regardless of habitat type. Movement pattern was in line with the data on congeneric species, although values were slightly higher. The analyses showed differences in movement degree among different sexes and life-cycle stages and indicated greater mobility of adult females compared to males and juveniles. The investigated parameters showed a great variability suggesting that even small-scale environmental factors can influence the species mobility. Finally, a change in the population structure has been observed, with the loss of large individuals in 2016 and reduced recruitment in 2017. These findings indicated the possible presence of stressors that could lead to the alteration of the seahorse population at Mar Piccolo of Taranto

Soil carbon budget account for the sustainability improvement of a Mediterranean vineyard area

Sustainable viticulture is suggested as an interesting strategy for achieving the objectives of global greenhouse gas (GHG) emission reduction in terms of mitigation and adaptation. However, knowledge and quantification of the contribution of sustainable vineyard management on climate change impact are needed. Although it is widely assessed by several authors that the agricultural stage has a great impact in the wine chain, very few studies have evaluated the greenhouse gas emission in this phase including the ability of soil to sequester carbon (C) or the off-farm C loss by erosion. This work aimed to provide a vineyard carbon budget (vCB) tool to quantify the impact of grape production on GHG emission including the effects of environmental characteristics and agricultural practices. The vCB was estimated considering four different soil management scenarios: conventional tillage (CT), temporary cover crop with a leguminous species in alternate inter-rows (ACC), temporary cover crop with a leguminous species (CC), permanent cover crop (PCC). The estimation of vCB was applied at territory level in a viticulture area in Sicily (2468 ha of vineyard) using empirical data. Results of the present study showed that the environmental characteristics strongly affect the sustainability of vineyard management; the highest contribution to total CO2 emission is, in fact, given by the C losses by erosion in sloping vineyards. Soils of studied vineyards are a source of CO2 due to the low C inputs and high mineralization rate, except for soil managed by CC which can sequester soil C, contributing positively to vCB. The highest total CO2 emission was estimated in vineyards under CT management (2.31 t ha−1y−1), followed by CC (1.27 t ha−1y−1), ACC (0.69 t ha−1y−1) and PCC (0.64 t ha−1y−1). Findings of vCB applied at territory level highlighted the key role of the evaluation of carbon budget (CB) on a larger scale to identify the CO2 emission in relation to climatic and environmental factors. The present study could contribute to provide suggestions to policymakers and farmers for reducing GHG emissions and promote more sustainable grape production practices

Carbon stock increases up to old growth forest along a secondary succession in Mediterranean island ecosystems

The occurrence of old-growth forests is quite limited in Mediterranean islands, which have been subject to particularly pronounced human impacts. Little is known about the carbon stocks of such peculiar ecosystems compared with different stages of secondary succession. We investigated the carbon variation in aboveground woody biomass, in litter and soil, and the nitrogen variation in litter and soil, in a 100 years long secondary succession in Mediterranean ecosystems. A vineyard, three stages of plant succession (high maquis, maquis-forest, and forest-maquis), and an old growth forest were compared. Soil samples at two soil depths (0-15 and 15-30 cm), and two litter types, relatively undecomposed and partly decomposed, were collected. Carbon stock in aboveground woody biomass increased from 6 Mg ha-1 in the vineyard to 105 Mg ha-1 in old growth forest. Along the secondary succession, soil carbon considerably increased from about 33 Mg ha-1 in the vineyard to about 69 Mg ha-1 in old growth forest. Soil nitrogen has more than doubled, ranging from 4.1 Mg ha-1 in the vineyard to 8.8 Mg ha-1 in old growth forest. Both soil parameters were found to be affected by successional stage and soil depth but not by their interaction. While the C/N ratio in the soil remained relatively constant during the succession, the C/N ratio of the litter strongly decreased, probably following the progressive increase in the holm oak contribution. While carbon content in litter decreased along the succession, nitrogen content slightly increased. Overall, carbon stock in aboveground woody biomass, litter and soil increased from about 48 Mg ha-1 in the vineyard to about 198 Mg ha-1 in old growth forest. The results of this study indicate that, even in Mediterranean environments, considerable amounts of carbon may be stored through secondary succession processes up to old growth forest.The occurrence of old-growth forests is quite limited in Mediterranean islands, which have been subject to particularly pronounced human impacts. Little is known about the carbon stocks of such peculiar ecosystems compared with different stages of secondary succession. We investigated the carbon variation in aboveground woody biomass, in litter and soil, and the nitrogen variation in litter and soil, in a 100 years long secondary succession in Mediterranean ecosystems. A vineyard, three stages of plant succession (high maquis, maquis-forest, and forest-maquis), and an old growth forest were compared. Soil samples at two soil depths (0-15 and 15-30 cm), and two litter types, relatively undecomposed and partly decomposed, were collected. Carbon stock in aboveground woody biomass increased from 6 Mg ha(-1) in the vineyard to 105 Mg ha(-1) in old growth forest. Along the secondary succession, soil carbon considerably increased from about 33 Mg ha(-1) in the vineyard to about 69 Mg ha(-1) in old growth forest. Soil nitrogen has more than doubled, ranging from 4.1 Mg ha(-1) in the vineyard to 8.8 Mg ha(-1) in old growth forest. Both soil parameters were found to be affected by successional stage and soil depth but not by their interaction. While the C/N ratio in the soil remained relatively constant during the succession, the C/N ratio of the litter strongly decreased, probably following the progressive increase in the holm oak contribution. While carbon content in litter decreased along the succession, nitrogen content slightly increased. Overall, carbon stock in aboveground woody biomass, litter and soil increased from about 48 Mg ha(-1) in the vineyard to about 198 Mg ha(-1) in old growth forest. The results of this study indicate that, even in Mediterranean environments, considerable amounts of carbon may be stored through secondary succession processes up to old growth forest

Bone mineral as a drug-seeking moiety and a waste dump

Bone is a dynamic tissue with a quarter of the trabecular and a fifth of the cortical bone being replaced continuously each year in a complex process that continues throughout an individual’s lifetime. Bone has an important role in homeostasis of minerals with non-stoichiometric hydroxyapatite bone mineral forming the inorganic phase of bone. Due to its crystal structure and chemistry, hydroxyapatite (HA) and related apatites have a remarkable ability to bind molecules. This review article describes the accretion of trace elements in bone mineral giving a historical perspective. Implanted HA particles of synthetic origin have proved to be an efficient recruiting moiety for systemically circulating drugs which can locally biomodulate the material and lead to a therapeutic effect. Bone mineral and apatite however also act as a waste dump for trace elements and drugs, which significantly affects the environment and human health

Evaluating the efficiency of DNA Metabarcoding to analyze the diet of Hippocampus guttulatus (Teleostea: Syngnathidae).

Seahorses are considered a flagship species for conservation efforts and due to their conservation status, improving knowledge on their dietary composition while applying a non-invasive approach, could be useful. Using Hippocampus guttulatus as a case study, the present study represents pioneering research into investigating the diet of seahorses by NGS-based DNA metabarcoding of fecal samples. The study developed and tested the protocol for fecal DNA metabarcoding during the feeding trials where captive seahorses were fed on a diet of known composition; the process was subsequently applied on fecal samples collected from wild individuals. The analysis of samples collected during the feeding trials indicated the reliability of the applied molecular approach by allowing the characterization of the effectively ingested prey. In the field study, among detected prey species, results revealed that the majority of the seahorse samples contained taxa such as Amphipoda, Decapoda, Isopoda, and Calanoida, while less common prey taxa were Gastropoda and Polyplacophora. As only a small amount of starting fecal material is needed and the sampling procedure is neither invasive nor lethal. The present study indicates DNA metabarcoding as useful for investigating seahorse diet and could help define management and conservation actions

Evaluating the efficiency of dna metabarcoding to analyze the diet of hippocampus guttulatus (Teleostea: Syngnathidae)

Seahorses are considered a flagship species for conservation efforts and due to their conservation status, improving knowledge on their dietary composition while applying a non-invasive approach, could be useful. Using Hippocampus guttulatus as a case study, the present study represents pioneering research into investigating the diet of seahorses by NGS-based DNA metabarcoding of fecal samples. The study developed and tested the protocol for fecal DNA metabarcoding during the feeding trials where captive seahorses were fed on a diet of known composition; the process was subsequently applied on fecal samples collected from wild individuals. The analysis of samples collected during the feeding trials indicated the reliability of the applied molecular approach by allowing the characterization of the effectively ingested prey. In the field study, among detected prey species, results revealed that the majority of the seahorse samples contained taxa such as Amphipoda, Decapoda, Isopoda, and Calanoida, while less common prey taxa were Gastropoda and Polyplacophora. As only a small amount of starting fecal material is needed and the sampling procedure is neither invasive nor lethal. The present study indicates DNA metabarcoding as useful for investigating seahorse diet and could help define management and conservation actions

Genetic structure of the long-snouted seahorse, Hippocampus guttulatus, in the Central-Western Mediterranean Sea

The seahorse Hippocampus guttulatus reaches its highest abundance in confined environments, where it has unique biological and ecological traits that suggest significant genetic differentiation among populations. In the present study, we aimed to reveal the genetic structure of this species by analysing eight microsatellite loci and a mitochondrial DNA region (cytochrome b) of eight populations from the Central-Western Mediterranean Sea, including lagoon sites. Levels of genetic diversity, as measured by the total number of alleles, number of private alleles, allelic richness and heterozygosity, ranged from low to moderate. The overall value of inbreeding was high, indicating a deficiency in heterozygotes. The haplotype network had a star-like construction, with the most common haplotype present in all populations. Data from the two molecular markers congruently displayed a similar pattern and revealed low genetic differentiation, notwithstanding predictions based on species traits. The observed genetic structure is probably the result of both historical population demographic events and current gene flow. The investigated lagoons, however, revealed a unique genetic profile, which is especially highlighted by the Taranto population. At this site, the results also showed altered values of observed/expected heterozygosity and allelic richness, a characteristic of marginal populations. Our study suggests that lagoon populations should be managed as distinct genetic units