Mediterranean Sea Urchin Paracentrotus Lividus Research Articles

Sea Urchin Food Waste into Bioactives: Collagen and Polyhydroxynaphtoquinones from P. lividus and S. granularis

Approximately 75,000 tons of different sea urchin species are globally harvested for their edible gonads. Applying a circular economy approach, we have recently demonstrated that non-edible parts of the Mediterranean Sea urchin Paracentrotus lividus can be fully valorized into high-value products: antioxidant pigments (polyhydroxynaphthoquinones—PHNQs) and fibrillar collagen can be extracted to produce innovative biomaterials for biomedical applications. Can waste from other edible sea urchin species (e.g., Sphaerechinus granularis) be similarly valorised? A comparative study on PHNQs and collagen extraction was conducted. PHNQ extraction yields were compared, pigments were quantified and identified, and antioxidant activities were assessed (by ABTS assay) and correlated to specific PHNQ presence (i.e., spinochrome E). Similarly, collagen extraction yields were evaluated, and the resulting collagen-based biomaterials were compared in terms of their ultrastructure, degradation kinetics, and resistance to compression. Results showed a partially similar PHNQ profile in both species, with significantly higher yield in P. lividus, while S. granularis exhibited better antioxidant activity. P. lividus samples showed higher collagen extraction yield, but S. granularis scaffolds showed higher stability. In conclusion, waste from different species can be successfully valorised through PHNQ and collagen extraction, offering diverse applications in the biomedical field, according to specific technical requirements.

Evaluation of sustainable feeds for “caviar” production in the Mediterranean sea urchin Paracentrotus lividus (Lamarck, 1816)

To improve the sustainability of aquaculture practices, a step towards the use of alternative nutrient sources (such as food processing discards) may secure the future of aquaculture sector, namely for emergent species, such as sea urchins. In this context, adult females of the commercial sea urchin Paracentrotus lividus were reared using four feeds based on lettuce discards (72%) and enriched (8%) with an animal-source ingredient (fish Sardina pilchardus, Feed-S; krill Euphausia superba, Feed-K; mussel Mytilus galloprovincialis, Feed-M; anchovy Engraulis encrasicolus discards, Feed-AD). A fifth feed, used as control treatment, was composed of macroalgae (Laminaria sp. and Ulva sp., Feed-UL). Feed performance was evaluated employing a new productive protocol, the Raking method, which propose testing feed effects on sea urchin caviar (oocytes rather than gonads) production. Thus, ingestion rates and absorption efficiency were measured to evaluate feed palatability. Somatic growth and caviar production, expressed introducing the ovosomatic index (OI) instead of the traditional gonadosomantic index, were measured to assess feed productive performances. Caviar quality was assessed by nutritional content and color. Ingestion rate results showed that all feeds were palatable, while findings on absorption efficiency showed differences between the five proposed feeds, with Feed-M and Feed-AD presenting the worst results. Somatic growth was promoted regardless the provided feeds, while OI resulted higher with Feed-K and Feed-M than the other feeds. All produced caviar resulted suitable for human consumption with high protein and fatty acid content, but caviar produced by Feed-UL showed the poorest nutritional profile. Similarly, Feed-UL led to the production of caviar with the lowest quality color, while Feed-S showed the best orange color. Lettuce-based feeds were therefore effective for feeding P. lividus as they stimulated production of high quality caviar. Findings support the exploitation of food discards for the production of eco-friendly feeds for sea urchin aquaculture.

Assessing the toxicity of aegerolysin-based bioinsecticidal complexes using the sea urchin Paracentrotus lividus as model organism

The use of alternative solutions for pest management to replace pesticides in agriculture is of great interest. Proteinaceous complexes deriving from edible oyster mushrooms were recently proposed as environmentally friendly bioinsecticides. Such complexes, composed of ostreolysin A6 (OlyA6) and pleurotolysin B (PlyB), target invertebrate-specific membrane sphingolipids in insect's midgut, causing death through the formation of transmembrane pores. In this work, the potential impact of OlyA6/PlyB complexes was tested in the Mediterranean sea urchin Paracentrotus lividus, as an indicator of environmental quality. The ability of the fluorescently tagged OlyA6 to bind sea urchin gametes (sperm, eggs), the lipidome of sea urchin gametes, and the potential toxic effects and developmental anomalies caused by OlyA6/PlyB complexes on P. lividus early development (embryo, larvae) were investigated. The binding of the fluorescently tagged OlyA6 could be observed only in sea urchin eggs, which harbor OlyA6 sphingolipid membrane receptors, conversely to sperm. High protein concentrations affected sea urchin fertilization (>750 µg/L) and early development (> 375 µg/L in embryos; >100 µg/L in larvae), by causing toxicity and morphological anomalies in embryos and larvae. The main anomalies consisted in delayed embryos and incorrect migration of the primary mesenchyme cells that caused larval skeletal anomalies. The classification of these anomalies indicated a slight environmental impact of OlyA6/PlyB complexes at concentrations higher than 750 µg/L. Such impact should not persist in the marine environment, due to the reversible anomalies observed in sea urchin embryos and larvae that may promote defense strategies. However, before promoting the use of OlyA6/PlyB complexes as bio-pesticides at low concentrations, further studies on other marine coastal species are needed.

Blue-Green Algae as Stimulating and Attractive Feeding Substrates for a Mediterranean Commercial Sea Urchin Species, Paracentrotus lividus.

Sea urchins rely on chemical senses to localize suitable food resources, therefore representing model species for chemosensory studies. In the present study, we investigated the chemical sensitivity of the Mediterranean sea urchin Paracentrotus lividus to the blue-green alga Aphanizomenon flos-aquae, namely "Klamath", and to a few amino acids chosen from the biochemical composition of the same algae. To this end, we used the "urchinogram" method, which estimates the movement rate of the sea urchins in response to chemicals. Our results showed that Klamath represents a strong chemical stimulus for P. lividus as it elicits an overall movement of spines, pedicellariae, and tube feet coupled, in some cases, to a coordinated locomotion of the animals. Sea urchins also displayed a sensitivity, even if to a lesser extent, to leucine, threonine, arginine, and proline, thus implying that the amino acids contained in Klamath may account, at least in part, for the stimulating effects exerted by the whole algae. Additionally, our results show that Klamath, as well as spirulina, another blue-green alga with high nutritional value, is very attractive for this sea urchin species. These findings gain further importance considering the potential profit of echinoderms for commercial consumers and their growing role in aquaculture. Klamath and spirulina combine high nutritional profiles with attractive and stimulating abilities and may be considered potential valuable feed supplements in sea urchin aquaculture.

The Diverse Transformer (Trf) Protein Family in the Sea Urchin Paracentrotus lividus Acts through a Collaboration between Cellular and Humoral Immune Effector Arms.

Sea urchins are long-living marine invertebrates with a complex innate immune system, which includes expanded families of immune receptors. A central immune gene family in sea urchins encodes the Transformer (Trf) proteins. The Trf family has been studied mainly in the purple sea urchin Strongylocentrotus purpuratus. Here, we explore this protein family in the Mediterranean Sea urchin Paracentrotus lividus. The PlTrf genes and predicted proteins are highly diverse and show a typical Trf size range and structure. Coelomocytes and cell-free coelomic fluid from P. lividus contain different PlTrf protein repertoires with a shared subset, that bind specifically to E. coli. Using FACS, we identified five different P. lividus coelomocyte sub-populations with cell surface PlTrf protein expression. The relative abundance of the PlTrf-positive cells increases sharply following immune challenge with E. coli, but not following challenge with LPS or the sea urchin pathogen, Vibrio penaeicida. Phagocytosis of E. coli by P. lividus phagocytes is mediated through the cell-free coelomic fluid and is inhibited by blocking PlTrf activity with anti-SpTrf antibodies. Together, our results suggest a collaboration between cellular and humoral PlTrf-mediated effector arms in the P. lividus specific immune response to pathogens.

Composition and geographic variation of the bacterial microbiota associated with the coelomic fluid of the sea urchin Paracentrotus lividus

In the present work, culture-based and culture-independent investigations were performed to determine the microbiota structure of the coelomic fluid of Mediterranean sea urchin Paracentrotus lividus individuals collected from two distinct geographical sites neighboring a high-density population bay and a nature reserve, respectively. Next Generation Sequencing analysis of 16S rRNA gene (rDNA) showed that members of the Proteobacteria, Bacteroidetes and Fusobacteria phyla, which have been previously reported to be commonly retrieved from marine invertebrates, dominate the overall population of microorganisms colonizing this liquid tissue, with minority bacterial genera exhibiting remarkable differences among individuals. Our results showed that there is a correlation between microbiota structure and geographical location of the echinoderm collection site, highlighting over-representation of metagenomic functions related to amino acid and bioactive peptides metabolism in specimens inhabiting the nature reserve. Finally, we also described the developmental delay and aberrations exhibited by sea urchin embryos exposed to distinct bacterial isolates, and showed that these defects rely upon hydrophilic compound(s) synthesized by the bacterial strains assayed. Altogether, our findings lay the groundwork to decipher the relationships of bacteria with sea urchins in their aquatic environment, also providing an additional layer of information to understand the biological roles of the coelomic fluid.

How sea urchins face microplastics: Uptake, tissue distribution and immune system response

Plastic pollution represents one of the major threats to the marine environment. A wide range of marine organisms has been shown to ingest microplastics due to their small dimensions (less than 1 mm). This negatively affects some biological processes, such as feeding, energy reserves and reproduction. Very few studies have been performed on the effect of microplastics on sea urchin development and virtually none on adults. The aim of this work was to evaluate the uptake and distribution of fluorescent labelled polystyrene microbeads (micro-PS) in the Mediterranean sea urchin Paracentrotus lividus and the potential impact on circulating immune cells. Differential uptake was observed in the digestive and water vascular systems as well as in the gonads based on microbeads size (10 and 45 μm in diameter). Treatment of sea urchins with particles of both sizes induced an increase of the total number of immune cells already after 24 h. No significant differences were observed among immune cell types. However, the ratio between red and white amoebocytes, indicative of sea urchin healthy status, increased with both particles. This effect was detectable already at 24 h upon exposure to smaller micro-PS (10 μm). An increase of intracellular levels of reactive oxygen and nitrogen species was observed at 24 h upon both micro-PS exposure, whereas at later time these levels became comparable to those of controls. A significant increase of total antioxidant capacity was observed after treatment with 10 μm micro-PS. Overall data provide the first evidence on polystyrene microbeads uptake and tissue distribution in sea urchins, indicating a stress-related impact on circulating immune cells.

Changes in the proteome of sea urchin Paracentrotus lividus coelomocytes in response to LPS injection into the body cavity.

BackgroundThe immune system of echinoderm sea urchins is characterised by a high degree of complexity that is not completely understood. The Mediterranean sea urchin Paracentrotus lividus coelomocytes mediate immune responses through phagocytosis, encapsulation of non-self particles, and production of diffusible factors including antimicrobial molecules. Details of these processes, and molecular pathways driving these mechanisms, are still to be fully elucidated.Principal findingsIn the present study we treated the sea urchin P. lividus with the bacterial lipopolysaccharide (LPS) and collected coelomocytes at different time-points (1, 3, 6 and 24 hours). We have shown, using label-free quantitative mass spectrometry, how LPS is able to modulate the coelomocyte proteome and to effect cellular pathways, such as endocytosis and phagocytosis, as soon as the immunomodulating agent is injected. The present study has also shown that treatment can modulate various cellular processes such as cytoskeleton reorganisation, and stress and energetic homeostasis.ConclusionsOur data demonstrates, through mass spectrometry and the following functional annotation bioinformatics analysis, how the bacterial wall constituent is sufficient to set off an immune response inducing cytoskeleton reorganisation, the appearance of clusters of heat shock proteins (Hsp) and histone proteins and the activation of the endocytic and phagocytic pathways. Data are available via ProteomeXchange with identifier PXD008439.

Sea urchin coelomocytes cultured on nanoporous aluminium oxide as a potential tool for marine environmental monitoring

Oceans and seas are of paramount importance to the health of planet Earth and human kind. Marine ecosystems should be defended against attack of polluting agents by continuous monitoring; the means of such monitoring should be as green as possible, i.e. based on sensors manufactured by biocompatible and easily disposable raw materials. In this study, we lay the basis for the future development of biosensors of marine environment based on sea urchin cells cultured on nanoporous aluminium oxide. These cells are promising as in previous works they demonstrated high response to stressors, and the proposed substrates have low costs since fabricated by inexpensive anodization process from consumer quality aluminium foils. Coelomocytes of the Mediterranean sea urchin Paracentrotus lividus were cultured on the nanoporous alumina for up to 5 days in vitro. Then, a biochemical characterization was carried out, checking the cholinergic system pathway by means of serotonin autofluorescence induced by aldehyde exposure and by expression and functionality of neuroactive molecules, such as acetylcholinesterase and muscarinic acetylcholine receptors. Both living cell quality and system biochemistry were not affected after the culture, and both electrical modulation and non-self-reactivity were maintained. These findings suggest the possibility of using the sea urchin immune cells cultured on nanoporous alumina as tools for monitoring the marine water quality, based on their electrical response.

Fatty Acids from Paracentrotus lividus Sea Urchin Shells Obtained via Rapid Solid Liquid Dynamic Extraction (RSLDE)

Sea urchins (Echinodermata, Echinoidea) are good a source of bioactive compounds belonging to different classes of natural substances. The edible Mediterranean sea urchin Paracentrotus lividus is a renowned animal model for study in different fields of biology, but it is intensively harvested for high commercial value due to the delicacy of its gonads. Most studies have focused on the composition and the nutritional value of P. lividus gonads (the edible part), but little interest has been taken in the other body parts, such as the shells and spines, which are generally considered waste material. The purpose of this study was to obtain an extract from sea urchin shells, with a green methodology of extraction, and to characterize the lipophilic components for potential applications. The shells of P. lividus were extracted via a very well performing technology based on rapid solid liquid dynamic extraction (RSLDE) implemented via an automated device (Naviglio Extractor®). The obtained extract shows the presence of fatty acids and their esters (methyl, ethyl and 1-glycerol esters). Gas chromatography-mass spectrometry (GC-MS) measurements were used to determine fatty acid abundance in the chromatographic fractions of the extract. Arachidonic acid (ARA), 5,8,11,14,17-eicosapentanoic acid (EPA), and 11-eicosenoic acids and their esters are the most abundant components. The presence of many polyunsaturated fatty acids (PUFA) in the extract, even in low percentages allows a future application in nutrition or medical use.

Cationic polystyrene nanoparticle and the sea urchin immune system: biocorona formation, cell toxicity, and multixenobiotic resistance phenotype

In order to assess the impact of nanoplastics on marine species, polystyrene nanoparticles (PS NPs) have been largely used as model particles. Here we studied the effects of 50 nm amino-modified PS-NH2 on Mediterranean sea urchin Paracentrotus lividus immune system cells (coelomocytes) in the presence of celomic fluid (CF) and at different NP concentrations (1, 5, 10, and 25 μg mL−1) and experimental conditions (absence or presence of EDTA). PS-NH2 acquired a protein corona once incubated with CF, dominated by the toposome precursor protein (TPP). In short-term cultures, a significant concentration- and time-dependent decrease in lysosomal membrane stability and apoptotic-like nuclear alterations were observed in phagocytes upon exposure to PS-NH2 (10 and 25 µg mL−1) in CF but they resulted abolished in the presence of EDTA confirming the role of TPP in triggering PS-NH2-coelomocytes interaction and toxicity. PS-NH2 did not alter MXR phenotype but the observed dose-dependent decrease in calcein accumulation suggests the ability of PS-NH2 to affect pump’s efflux activity. Overall results encourage additional studies on positively charged nanoplastics, since the observed effects on sea urchin coelomocytes as well as the TPP corona formation might represent a first step for addressing their impact on sensitive marine species.

Effect of five benthic diatoms on the survival and development of Paracentrotus lividus post-larvae in the laboratory

The Mediterranean sea urchin Paracentrotus lividus Lamark, 1816 is a resource as food and model organism for scientific research. Increasing market demand, commercial fisheries and destructing harvesting methods produced a dramatic reduction of natural stocks along the Mediterranean coasts. The techniques for in vitro fertilization and growth of larvae and adults are well known but various bottlenecks still hinder the industrial maturity of its aquaculture. In particular, the transition from planktonic larvae to benthic juveniles, as well as their correct development and survival, still represent critical phases, since larval and post-larval experiences are the primary determinant of juvenile fitness. Thus, techniques improving survival and settlement rates in the first two months after fertilization could considerably improve the effectiveness of echinoculture practices. This study was conducted to determine, for the first time, the effect of strictly benthic diatoms on P. lividus post-larval performances, as compared to other micro- and macro-algae. In addition, three larval dietary treatments were applied, to confirm previous findings on the efficacy of algae and formulated diets. In particular, survival and ability to produce competent larvae for settlement were tested in groups subjected to three algal diets (Isochrisis galbana, Rhodomonas baltica and Dunaliella tertiolecta), all integrated with a formulated food. Furthermore, six post-larval feeding regimes, i.e., the benthic diatoms Cocconeis scutellum parva, Diploneis sp., Navicula incerta, Cylindrotheca closterium and Nanofrustulum shiloi, compared with Ulva rigida along with a negative control (absence of food), were tested on larvae deriving from the most effective treatment. Our results confirmed the efficacy of Dunaliella tertiolecta integrated with a formulated food, consistently producing about 60% survival. Furthermore, the most adhesive benthic diatom, Cocconeis scutellum parva, sustained settlement (about 63%) and good survival in the first two months of life of sea urchins.

Ocean acidification modulates the incorporation of radio-labeled heavy metals in the larvae of the Mediterranean sea urchin Paracentrotus lividus

The marine organisms which inhabit the coastline are exposed to a number of anthropogenic pressures that may interact. For instance, the accumulation of toxic metals present in coastal waters is expected to be modified by ocean acidification through e.g. changes in physiological performance and/or elements availability. Changes in bioaccumulation due to lowering pH are likely to be differently affected depending on the nature (essential vs. non-essential) and speciation of each element. The Mediterranean is of high concern for possible cumulative effects due to strong human influences on the coastline.The aim of this study was to determine the effect of ocean acidification (from pH 8.1 down to −1.0 pH units) on the incorporation kinetics of six trace metals (Mn, Co, Zn, Se, Ag, Cd, Cs) and one radionuclide (241Am) in the larvae of an economically- and ecologically-relevant sea urchin of the Mediterranean coastline: Paracentrotus lividus. The radiolabelled metals and radionuclides added in trace concentrations allowed precise tracing of their incorporation in larvae during the first 74 h of their development.Independently of the expected indirect effect of pH on larval size/developmental rates, Paracentrotus lividus larvae exposed to decreasing pHs incorporated significantly more Mn and Ag and slightly less Cd. The incorporation of Co, Cs and 241Am was unchanged, and Zn and Se exhibited complex incorporation behaviors. Studies such as this are necessary prerequisites to the implementation of metal toxicity mitigation policies for the future ocean. We discuss possible reasons and mechanisms for the specific effect of pH on each metals.

Cell mediated immune response of the Mediterranean sea urchin Paracentrotus lividus after PAMPs stimulation

The Mediterranean sea urchin (Paracentrotus lividus) is of great ecological and economic importance for the European aquaculture. Yet, most of the studies regarding echinoderm's immunological defense mechanisms reported so far have used the sea urchin Strongylocentrotus purpuratus as a model, and information on the immunological defense mechanisms of Paracentrotus lividus and other sea urchins, is scarce. To remedy this gap in information, in this study, flow cytometry was used to evaluate several cellular immune mechanisms, such as phagocytosis, cell cooperation, and ROS production in P. lividus coelomocytes after PAMP stimulation. Two cell populations were described. Of the two, the amoeboid-phagocytes were responsible for the phagocytosis and ROS production. Cooperation between amoeboid-phagocytes and non-adherent cells resulted in an increased phagocytic response. Stimulation with several PAMPs modified the phagocytic activity and the production of ROS. The premise that the coelomocytes were activated by the bacterial components was confirmed by the expression levels of two cell mediated immune genes: LPS-Induced TNF-alpha Factor (LITAF) and macrophage migration inhibitory factor (MIF). These results have helped us understand the cellular immune mechanisms in P. lividus and their modulation after PAMP stimulation.

Detection of malformations in sea urchin plutei exposed to mercuric chloride using different fluorescent techniques

Embryos of Mediterranean sea urchin Paracentrotus lividus and subtropical Echinometra mathaei were exposed to 5,10, 15 and 20µgL−1, and to 1, 2, 3 and 4µgL−1 mercuric chloride (HgCl2), respectively. The effective concentration (EC50) inducing malformation in 50% of 4-arm pluteus stage (P4) was 16.14µgL−1 for P. lividus and 2.41µgL−1 for E. mathaei. Two-photon (TP), second (SHG) and third harmonic generation (THG) microscopy techniques, TUNEL staining, propidium iodide (PI) and Hoechst 33342 probes were used to detect light signals or to stain apoptotic and necrotic cells in fixed and alive plutei. Signals were detected differently in the two species: TP fluorescence, commonly associated with apoptotic cells, did not increase with increasing HgCl2 concentrations in P. lividus and in fact, the TUNEL did not reveal induction of apoptosis. PI fluorescence increased in P. lividus in a dose-dependent manner, suggesting a loss of cell permeability. In E. mathaei plutei TP fluorescence increased at increasing HgCl2 concentrations. THG microscopy revealed skeletal rods in both species. Different fluorescent techniques, used in this study, are proposed as early-warning systems to visualize malformations and physiological responses in sea urchin plutei.

Review: Morphofunctional and biochemical markers of stress in sea urchin life stages exposed to engineered nanoparticles.

We describe the use of different life stages of the Mediterranean sea urchin Paracentrotus lividus for the assessment of the possible risk posed by nanoparticles (NPs) in the coastal water. A first screening for the presence of NPs in sea water may be obtained by checking their presence inside tissues of organisms taken from the wild. The ability of NPs to pass from gut to the coelomic fluid is demonstrated by accumulation in sea urchin coelomocytes; the toxicity on sperms can be measured by embryotoxicity markers after sperm exposure, whereas the transfer through the food chain can be observed by developmental anomalies in larvae fed with microalgae exposed to NPs. The most used spermiotoxicity and embryotoxicity tests are described, as well as the biochemical and histochemical analyses of cholinesterase (ChE) activities, which are used to verify toxicity parameters such as inflammation, neurotoxicity, and interference in cell-to-cell communication. Morphological markers of toxicity, in particular skeletal anomalies, are described and classified. In addition, NPs may impair viability of the immune cells of adult specimens. Molecular similarity between echinoderm and human immune cells is shown and discussed. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1552-1562, 2016.

Embryotoxicity and spermiotoxicity of nanosized ZnO for Mediterranean sea urchin Paracentrotus lividus

The effect of nano ZnO (nZnO) upon the fertilization and early development of embryos of the Mediterranean sea urchin Paracentrotus lividus is reported herein for the first time. Zn ion (ZnCl2) and bulk ZnO (bZnO) toxicity were assessed for comparison. The embryotoxicity tests showed a 100% effect already at 1μM of nZnO (expressed as [Zn]) while bZnO and ZnCl2 showed EC50s of 0.98 [0.88–1.19]μM [Zn] and 2.02 [1.97–2.09]μM [Zn], respectively. Noteworthy, the frequency of developmental defects for the three compounds was dissimilar and a specific trend for larval skeletal abnormality produced by nZnO was observed.The sperm fertilization capability was only slightly affected by the tested chemicals while the effects were dramatic on the offspring quality of sperms exposed to ZnO compounds resulting in an early block of the regular larval development.ZnO toxicity seems related not only to Zinc ions but also to some surface interactions of particle/aggregates with target organisms and/or with the seawater.

Relationships between algal food and gut and gonad conditions in the Mediterranean sea urchin Paracentrotus lividus (Lam.)

A study was conducted on the population of Paracentrotus lividus (Lamarck, 1816) in a Mediterranean infralittoral bottomof southern of Spain to characterize the relationships between the macroalgal food ingested and the gut and gonad conditions of individuals. Over a full annual cycle (November 2008 to October 2009) composition of the gut content was analyzed monthly and seasonally, the gastrointestinal (GII), repletion (RI) and gonadosomatic (gonad) (GI) indices were calculated, and the stage of gonad maturity of the population was assessed. The GII and RI were found to be strongly correlated, so only the RI was considered in the subsequent analysis. The prevalence of Phaeophyceae and local species of this macroalgal group in the gut content of the sea urchins throughout the year suggests that in conditions of abundant resources, with high levels of algal diversity and no effective limits on supply, brown algae are the main component of the natural diet of P. lividus. Comparison of the physiologicalindices and the algal fractions of gut content identified relationships throughout the year between RI, the stage of gonad maturity and GI. Specifically, these indices were found to be associated with the abundance of Rhodophyta ingested, although in different ways: GI was related to the consumption of fleshy (non-calcified) red algae and the RI, though less statistically significantly, to the consumption of calcified (articulate and encrusting).

Toxic effects of pentachlorophenol, azinphos-methyl and chlorpyrifos on the development of Paracentrotus lividus embryos

The application of many current-use pesticides has increased after the disuse of persistent, bioaccumulative or toxic ones as DDT or chlordane. Many of the used pesticides are considered less dangerous towards the environment for their physico-chemical properties. This study investigated the toxic effects of three current-use pesticides, pentachlorophenol (PCP), azinphos-methyl (AZM), and chlorpyrifos, on Mediterranean sea urchin Paracentrotus lividus early development and offspring quality. The experimental results showed that the most toxic pesticides were PCP and AZM at EC50 level. Nevertheless at low concentration PCP resulted the less toxic compound and showed EC1 value more protective than NOEC. PCP at high concentration seemed to modify cytoskeleton assembly, while at low concentrations, it could alter the deposition of the larval skeleton. OPs at low concentrations until 300 μg/l showed a similar toxicological behaviour with a trend corresponding to the pesticide concentrations. At high concentration (500 μg/l) the effect mainly observed was the embryos pre-larval arrest. This investigation highlighted the relevance to evaluate, in coastal seawaters, the levels of the used pesticides to understand the real impact on benthic populations mainly in sites characterized by intensive agriculture or floriculture activities, such as the coastal areas of the Mediterranean Sea.

Time and space: genetic structure of the cohorts of the common sea urchin Paracentrotus lividus in Western Mediterranean

Spatio-temporal variability in settlement and recruitment, high mortality during the first life-history stages, and selection may determine the genetic structure of cohorts of long-lived marine invertebrates at small scales. We conducted a spatial and temporal analysis of the common Mediterranean Sea urchin Paracentrotus lividus to determine the genetic structure of cohorts at different scales. In Tossa de Mar (NW Mediterranean), recruitment was followed over 5 consecutive springs (2006–2010). In spring 2008, recruits and two-year-old individuals were collected at 6 locations along East and South Iberian coasts separated from 200 to over 1,100 km. All cohorts presented a high genetic diversity based on a fragment of mtCOI. Our results showed a marked genetic homogeneity in the temporal monitoring and a low degree of spatial structure in 2006. In 2008, coupled with an abnormality in the usual circulation patterns in the area, the genetic structure of the southern populations studied changed markedly, with arrival of many private haplotypes. This fact highlights the importance of point events in renewing the genetic makeup of populations, which can only be detected through analysis of the cohort structure coupling temporal and spatial perspectives.