Suchergebnisse

Este artículo contiene 12 páginas, 4 figuras, 1 tabla. ; Background: Classic ecological formulations of predator–prey interactions often assume that predators and prey interact randomly in an information-limited environment. In the feld, however, most prey can accurately assess predation risk by sensing predator chemical cues, which typically trigger some form of escape response to reduce the probability of capture. Here, we explore under laboratory-controlled conditions the long-term (minutes to hours) escaping response of the sea urchin Paracentrotus lividus, a key species in Mediterranean subtidal macrophyte communities. Methods: Behavioural experiments involved exposing a random sample of P. lividus to either one of two treatments: (i) control water (fltered seawater) or (ii) predator-conditioned water (with cues from the main P. lividus benthic predator—the gastropod Hexaplex trunculus). We analysed individual sea urchin trajectories, computed their heading angles, speed, path straightness, difusive properties, and directional entropy (as a measure of path unpredictability). To account for the full picture of escaping strategies, we followed not only the frst instants post-predator exposure, but also the entire escape trajectory. We then used linear models to compare the observed results from control and predators treatments. Results: The trajectories from sea urchins subjected to predator cues were, on average, straighter and faster than those coming from controls, which translated into diferences in the difusive properties and unpredictability of their movement patterns. Sea urchins in control trials showed complex difusive properties in an information-limited environment, with highly variable trajectories, ranging from Brownian motion to superdifusion, and even marginal ballistic motion. In predator cue treatments, variability reduced, and trajectories became more homogeneous and predictable at the edge of ballistic motion. Conclusions: Despite their old evolutionary origin, lack of cephalization, and homogenous external appearance, the trajectories that sea urchins displayed in information-limited environments were complex and ranged widely between individuals. Such variable behavioural repertoire appeared to be intrinsic to the species and emerged when the animals were left unconstrained. Our results highlight that fear from predators can be an important driver of sea urchin movement patterns. All in all, the observation of anomalous difusion, highly variable trajectories and the behavioural shift induced by predator cues, further highlight that the functional forms currently used in classical predator–prey models are far from realistic. ; The Spanish Ministry of Science and Innovation funded this research (project CTM2010-22273-C02, CTM2017-86695-C3-1-R, CTM2017-86695-C3-3-R, and CGL78156-C2-R1). JFP acknowledges fnancial support from the Spanish Ministry of Education (scholarship AP2008-01601) and the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 795315. ; Peer reviewed

Este artículo contiene 13 páginas, 6 figuras, 2 tablas. ; Predators exert a strong influence on ecological communities by reducing the abundance of prey (consumptive effects) and shaping their foraging behavior (non-consumptive effects). Although the prevalence of trophic cascades triggered by non-consumptive effects is increasingly recognized in a wide range of ecosystems, how its relative strength changes as prey individuals grow in size along various life stages remains poorly resolved. We investigated how the effects of predators vary with the ontogeny of a key herbivorous sea urchin, which is responsible for transforming diverse macroalgal forests to a barren state dominated by bare rock and encrusting coralline algae. We conducted a series of field and laboratory experiments to determine how susceptibility to predation, prey behavioral responses, and grazing impact on algal cover vary with sea urchin size. The consumptive effects of predators were greater on smaller sea urchin size classes, which were more susceptible to predation. Unexpectedly however, predator non-consumptive effects acted only on larger sea urchins, significantly reducing their grazing activity in the presence of predator cues. Crucially, only these larger sea urchins were capable of overgrazing macroalgae in the field, with non-consumptive effects reducing sea urchin foraging activity and macroalgal grazing impact by 60%. The decoupling between risk and fear as prey grow indicates that the strength of consumptive and non-consumptive trophic cascades may act differently at different ontogenetic stages of prey. While the consumptive effects of predators directly influence population numbers, the consequences of non-consumptive effects may far outlive consumptive effects as prey grow, finding refuge in size, but not from fear. ; The Spanish Ministry of Science and Innovation funded this research (UMBRAL; Respuestas de la vegetaci on marina bent onica al estr es: transiciones cr ıticas, resiliencia y oportunidades de gesti on', CTM2017-86695-C3-3-R) and supported J. Boada's scholarship (no. BES-2011-043630). The Spanish National Research Council supported R. Arthur's visitorship with the Memorandum of Understanding between CEAB-IMEDEA-NCF. J. Boada acknowledges the funding received by the Australian Government (ERF_PDR_5888_2017). J. F. Pag es acknowledges financial support from the Welsh Government and Higher Education Funding Council for Wales through the S^er Cymru National Research Network for Low Carbon, Energy and Environment. ; Peer reviewed

Short communication ; The seagrass Posidonia oceanica is able to reproduce by asexual formation of plantlets directly in the inflorescence. Pseudoviviparous plantlets were observed during May 2004 in 26% of the inflorescences in a P. oceanica meadow off the island of Formentera (Balearic Islands, Western Mediterranean Sea). We do not know how frequently pseudovivipary occurs in Posidonia oceanica, nor the mechanisms triggering it, but this strategy can contribute significantly to short-distance dispersal and meadow maintenance, which is especially relevant in a species whose meadows can persist for thousands of years and whose colonization of new space occurs very slowly. ; This work was supported by the Fisheries Department (Direcció General de Pesca) of the Balearic Government. ; Peer reviewed

Este artículo contiene 12 páginas, 7 figuras, 2 tablas. ; The relative benefts of group foraging change as animals grow. Metabolic requirements, competitive abilities and predation risk are often allometric and infuenced by group size. How individuals optimise costs and benefts as they grow can strongly infuence consumption patterns. The shoaling fsh Sarpa salpa is the principal herbivore of temperate Posidonia oceanica seagrass meadows. We used in-situ observations to describe how ontogeny infuenced S. salpa individual feeding behaviour, shoaling behaviour and group foraging strategies, and its potential consequences to seagrass meadows. Shoaling was strongly infuenced by body length: shoals were highly length-assorted and there was a clear positive relationship between body length and shoal size. Foraging strategies changed dramatically with shoal size. Small shoals foraged simultaneously and scattered over large areas. In contrast, larger shoals (made of larger individuals) employed a potentially cooperative strategy where individuals fed rotationally and focused in smaller areas for longer times (spot feeding). Thus, as individuals grew, they increased their potential impact as well, not merely because they consumed more, but because they formed larger shoals capable of considerably concentrating their grazing within the landscape. Our results indicate that ontogenetic shifts in group foraging strategies can have large ecosystem-wide consequences when the species is an important ecosystem modifer. ; Te Spanish Ministry of Science funded this research through RECCAM project (CMT2013-48027-C03-R). Te Spanish National Research Council supported Rohan Arthur's visitorship with the Memorandum of Understanding between CEAB-IMEDEA-NCF. Jordi F. Pages acknowledges fnancial support from the Welsh Government and Higher Education Funding Council for Wales through the Sȇr Cymru National Research Network for Low Carbon, Energy and Environment and from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant Agreement No 795315. Te work was supported by UMBRAL National Project CTM2017-86695-C3-3-R. ; Peer reviewed

9 páginas, 3 tablas, 4 figuras. ; We used the disturbance resulting from a once in a 100-yr storm on the northwest Mediterranean coast to examine the extent of the disturbance, the tolerance thresholds to burial, and the medium-term response of the long-lived Posidonia oceanica seagrass. Sediment burial at 12 surveyed areas was particularly strong in shallow meadows, with 23% of their surfaces buried, on average, under more than 10 cm of sediment. In contrast, less than 5% of the meadow was affected at deeper locations. At three sites, we tracked short-term mortality along a gradient of sediment burial. Survival response to burial was clearly nonlinear, with a significant threshold at 4–5 cm, beyond which shoot mortality was 100%. To track medium-term potential recovery, we established permanent plots subject to three sediment burial levels (0–5, 5–10, and . 10 cm burial) in four meadows. Where the initial shoot mortality was 100%, we recorded no shoot recovery over the 4-yr period. In the remaining plots, where some shoots remained alive, we detected either further mortality or shoot recovery of 7% per year on average. Extreme storm events can result in sudden catastrophic losses of seagrass cover in shallow P. oceanica meadows. In the long term and due to the long return time of such storms, the species may still be able to recover despite its low recovery potential. However, added anthropogenic stressors, including climate change, may seriously test the ability of long-lived shallow seagrass ecosystems to resist high-intensity natural disturbances and may be critical for its persistence. ; This research was funded by the Spanish Ministry of Science and Innovation (projects CTM2010-22273-C02-01 and 02) and from an Intramural Project from Consejo Superior de Investigaciones Cientı´ficas (CSIC, 201330E062). The CSIC supported AG (scholarship JAEPre_08_00466), the Spanish Ministry of Education supported J.P. (scholarship AP2008-01601), and the Catalan Government supported G.R. (scholarship GR 080126). ; Peer reviewed

Este artículo contiene 8 páginas, 6 figuras, 1 tabla. ; Interactions among species are essential in shaping ecological communities, although it is not always clear under what conditions they can persist when the number of species involved is higher than two. Here we describe a three-species assemblage involving the seagrass Cymodocea nodosa, the pen shell Pinna nobilis and the herbivore sea urchin Paracentrotus lividus, and we explore the mechanisms allowing its persistence through field obser vations and manipulative experiments. The abundance of pen shells was higher in seagrass beds than in bare sand, suggesting a recruitment facilitation. The presence of sea urchins, almost exclusively attached or around pen shells, indicated habitat facilitation for sea urchins, which overgrazed the meadow around the pen shells forming seagrass-free halos. Our results suggest that this system persists thanks to: (i) the behavioral reluctance of sea urchins to move far from pen shells, making their impact on seagrass strictly local, (ii) the sparse distri bution of pen shells and (iii) the plant's resistance mechanisms to herbivory. Unpacking these mechanisms allows a better understanding of how ecological communities are assembled. ; This study received financial support from the Spanish Government (project UM BRAL CTM2017-86695-C3-1R; CTM2017-86695-C3-3R). The Spanish National Research Council supported R. Arthur's visitorship with the Memorandum of Understanding between CEAB-NCF. ; Peer reviewed

6 páginas, 2 figuras ; Efforts to conserve globally declining herbivorous green sea turtles have resulted in promising growth of some populations. These trends could significantly impact critical ecosystem services provided by seagrass meadows on which turtles feed. Expanding turtle populations could improve seagrass ecosystem health by removing seagrass biomass and preventing of the formation of sediment anoxia. However, overfishing of large sharks, the primary green turtle predators, could facilitate turtle populations growing beyond historical sizes and trigger detrimental ecosystem impacts mirroring those on land when top predators were extirpated. Experimental data from multiple ocean basins suggest that increasing turtle populations can negatively impact seagrasses, including triggering virtual ecosystem collapse. Impacts of large turtle populations on seagrasses are reduced in the presence of intact shark populations. Healthy populations of sharks and turtles, therefore, are likely vital to restoring or maintaining seagrass ecosystem structure, function, and their value in supporting fisheries and as a carbon sink. ; Studies in Shark Bay were funded byNSF grantsOCE0526065 and OCE0745606 and Florida International University.Work in India was supported by the Norwegian Institute of Nature Research, the Rufford Small Grants Programme and Spanish Ministry of Economia y Competitividad [projects: CTM2010-22273-C02-02 and PIE-201330E062 (CSIC)]. Work in Bermuda was funded by the Department of Conservation Services, Government of Bermuda and B. Dilke, a private benefactor. This is contribution # 681 of the Southeast Environmental Research Center, Florida International University, contribution # BBP218 of the BBP series at the Bermuda Department of Conservation Services library, and contribution 76 of the Shark Bay Ecosystem Research Project. ; Peer reviewed

Este artículo contiene 10 páginas, 4 figuras. ; The prevalence of local adaptation and phenotypic plasticity among populations is critical to accurately predicting when and where climate change impacts will occur. Currently, comparisons of thermal performance between populations are untested for most marine species or overlooked by models predicting the thermal sensitivity of species to extirpation. Here we compared the ecological response and recovery of seagrass populations (Posidonia oceanica) to thermal stress throughout a year-long translocation experiment across a 2800- km gradient in ocean climate. Transplants in central and warm-edge locations experienced temperatures > 29°C, representing thermal anomalies > 5°C above long-term maxima for cool-edge populations, 1.5°C for central and < 1°C for warm-edge populations. Cool-edge, central and warm-edge populations differed in thermal performance when grown under common conditions, but patterns contrasted with expectations based on thermal geography. Cool-edge populations did not differ from warm-edge populations under common conditions and performed significantly better than central populations in growth and survival. Our findings reveal that thermal performance does not necessarily reflect the thermal geography of a species. We demonstrate that warm-edge populations can be less sensitive to thermal stress than cooler, central populations suggesting that Mediterranean seagrasses have greater resilience to warming than current paradigms suggest. ; This study was funded by Fundacion BBVA (project Interbioclima). SB received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 659246, Juan de la Cierva Formacion contract from the Spanish Ministry of Economy, Industry and Competitiveness and the Australian Research Council (DE200100900). NM and SB received funding from the Spanish Ministry of Economy, Industry and Competitiveness (MedShift, CGL2015-71809-P). JB received funding from the Spanish Ministry of Science and Innovation, Juan de la Cierva FJC18-035566-I. TA received funding from the Spanish Ministry of Science and Innovation (Project: UMBRAL, CTM2017-86695-C3-1-R). ; Peer reviewed

Seagrass meadows, key ecosystems supporting fisheries, carbon sequestration and coastal protection, are globally threatened. In Europe, loss and recovery of seagrasses are reported, but the changes in extent and density at the continental scale remain unclear. Here we collate assessments of changes from 1869 to 2016 and show that 1/3 of European seagrass area was lost due to disease, deteriorated water quality, and coastal development, with losses peaking in the 1970s and 1980s. Since then, loss rates slowed down for most of the species and fast-growing species recovered in some locations, making the net rate of change in seagrass area experience a reversal in the 2000s, while density metrics improved or remained stable in most sites. Our results demonstrate that decline is not the generalised state among seagrasses nowadays in Europe, in contrast with global assessments, and that deceleration and reversal of declining trends is possible, expectingly bringing back the services they provide. ; This research was supported by the COST Action ES0906. C.B.d.l.S. acknowledges the support by the Short-Term Scientific Missions (COST-STSM-ES0906-06377, -06441 and -06419) and the Portuguese Foundation for Science and Technology (FCT) fellowship (SFRH/BPD/119344/2016). C.B.d.l.S. and R.S. acknowledge the support of FCT through project UID/Multi/04326/2019. D.K-J. was supported by the European Union (WISER 226273), the Danish Strategic Science Foundation (NOVAGRASS, 0603-00003DSF), and the Ministry of Environment and Food of Denmark (33010-NIFA-16-651). N.M. was supported by Spanish Ministry of Economy, Industry and Competitiveness (MedShift, CGL2015-71809-P), by the European Union (M&M's, EVK3-CT-2000–00044 and WISER 226273), by the Fundación BBVA (Proyecto Praderas), and the Spanish Government (MEDEIG. CTM2009–07013). King Abdullah University of Science and Technology (KAUST) supported C.M.D. through baseline funding. J.M.R. acknowledges the project Monitoring network of Posidonia oceanica meadows and global climate change of the Murcia Region funded by the Autonomous Government of the Murcia Region (General Directorate of Livestock and Fishery), the European Fishery Fund (EFF 2007–2013), and European Maritime and Fisheries Fund (EMFF 2014–2020), and the Spanish Ministry of Industry, Economy and Competitiveness (UMBRAL, CTM2017-86695-C3-2-R).

Seagrass meadows, key ecosystems supporting fisheries, carbon sequestration and coastal protection, are globally threatened. In Europe, loss and recovery of seagrasses are reported, but the changes in extent and density at the continental scale remain unclear. Here we collate assessments of changes from 1869 to 2016 and show that 1/3 of European seagrass area was lost due to disease, deteriorated water quality, and coastal development, with losses peaking in the 1970s and 1980s. Since then, loss rates slowed down for most of the species and fast-growing species recovered in some locations, making the net rate of change in seagrass area experience a reversal in the 2000s, while density metrics improved or remained stable in most sites. Our results demonstrate that decline is not the generalised state among seagrasses nowadays in Europe, in contrast with global assessments, and that deceleration and reversal of declining trends is possible, expectingly bringing back the services they provide. ; COST Action - ES0906; Portuguese Foundation for Science and Technology (FCT) fellowship - SFRH/BPD/119344/2016; FCT - UID/Multi/04326/2019; European Union -06441C EVK3-CT-2000-00044 WISER 226273; Danish Strategic Science Foundation (NOVAGRASS) - 0603-00003DSF; Ministry of Environment and Food of Denmark - 33010-NIFA-16-651; Spanish Ministry of Economy, Industry and Competitiveness (MedShift) - CGL2015-71809-P; Fundacion BBVA (Proyecto Praderas); Spanish Government - MEDEIG. CTM2009-07013; King Abdullah University of Science and Technology (KAUST); European Fishery Fund (EFF 2007-2013); European Maritime and Fisheries Fund (EMFF 2014-2020); Spanish Ministry of Industry, Economy and Competitiveness (UMBRAL) - CTM2017-86695-C3-2-R; Autonomous Government of the Murcia Region (General Directorate of Livestock and Fishery); Short-Term Scientific Missions - COST-STSM-ES0906-06377; COST-STSM-ES0906-06441; COST-STSM-ES0906-06419; ; info:eu-repo/semantics/publishedVersion

Seagrass meadows, key ecosystems supporting fisheries, carbon sequestration and coastal protection, are globally threatened. In Europe, loss and recovery of seagrasses are reported, but the changes in extent and density at the continental scale remain unclear. Here we collate assessments of changes from 1869 to 2016 and show that 1/3 of European seagrass area was lost due to disease, deteriorated water quality, and coastal development, with losses peaking in the 1970s and 1980s. Since then, loss rates slowed down for most of the species and fast-growing species recovered in some locations, making the net rate of change in seagrass area experience a reversal in the 2000s, while density metrics improved or remained stable in most sites. Our results demonstrate that decline is not the generalised state among seagrasses nowadays in Europe, in contrast with global assessments, and that deceleration and reversal of declining trends is possible, expectingly bringing back the services they provide. ; This research was supported by the COST Action ES0906. C.B.d.l.S. acknowledges the support by the Short-Term Scientific Missions (COST-STSM-ES0906-06377, -06441 and -06419) and the Portuguese Foundation for Science and Technology (FCT) fellowship (SFRH/BPD/119344/2016). C.B.d.l.S. and R.S. acknowledge the support of FCT through project UID/Multi/04326/2019. D.K-J. was supported by the European Union (WISER 226273), the Danish Strategic Science Foundation (NOVAGRASS, 0603-00003DSF), and the Ministry of Environment and Food of Denmark (33010-NIFA-16-651). N.M. was supported by Spanish Ministry of Economy, Industry and Competitiveness (MedShift, CGL2015-71809-P), by the European Union (M&M's, EVK3-CT-2000–00044 and WISER 226273), by the Fundación BBVA (Proyecto Praderas), and the Spanish Government (MEDEIG. CTM2009–07013). King Abdullah University of Science and Technology (KAUST) supported C.M.D. through baseline funding. J.M.R. acknowledges the project Monitoring network of Posidonia oceanica meadows and global climate ...

Este artículo contiene 9 páginas, 5 figuras, 1 tabla. ; Seagrass meadows, key ecosystems supporting fisheries, carbon sequestration and coastal protection, are globally threatened. In Europe, loss and recovery of seagrasses are reported, but the changes in extent and density at the continental scale remain unclear. Here we collate assessments of changes from 1869 to 2016 and show that 1/3 of European seagrass area was lost due to disease, deteriorated water quality, and coastal development, with losses peaking in the 1970s and 1980s. Since then, loss rates slowed down for most of the species and fast rowing species recovered in some locations, making loss rate in seagrass area experience a reversal in the 2000s, while density metrics improved or remained stable in most sites. Our results demonstrate that decline is not the generalised state among seagrasses nowadays in Europe, in contrast with global assessments, and that deceleration and reversal of declining trends is possible, expectingly bringing back the services they provide. ; This research was supported by the COST Action ES0906. C.B.d.l.S. acknowledges the support by the Short-Term Scientific Missions (COST-STSM-ES0906-06377, -06441 and -06419) and the Portuguese Foundation for Science and Technology (FCT) fellowship (SFRH/BPD/119344/2016). C.B.d.l.S. and R.S. acknowledge the support of FCT through the projects UID/Multi/04326/2013 and FCT UID/MAR/00350/2018. N.M. was supported by Spanish Ministry of Economy, Industry and Competitiveness (MedShift, CGL2015-71809-P), by the European Union (M&M's, EVK3-CT-2000–00044 and WISER 226273), by the Fundación BBVA (Proyecto Praderas), and the Spanish Government (MEDEIG. CTM2009–07013). King Abdullah University of Science and Technology (KAUST) supported C.M.D. through baseline funding. J.M.R. acknowledges the project Monitoring network of Posidonia oceanica meadows and global climate change of the Murcia Region funded by the Autonomous Government of the Murcia Region (General Directorate of Livestock and Fishery), the European Fishery Fund (EFF 2007–2013), and European Maritime and Fisheries Fund (EMFF 2014–2020). ; Peer reviewed