Hábitat coralígeno: patrones de distribución vertical de conjuntos de macroalgas

The present study investigates patterns of distribution of macroalgal coralligenous assemblages in relation to depth and evaluates the role of different environmental conditions on these patterns. Two depths (30 and 40 m) were investigated off small islands and off continental coasts in order to select two different environmental conditions. Results showed differences between depths in the structure of assemblages around islands, while along the continental coasts these patterns were not evident. Moreover, differences between assemblages related to different environmental conditions were more evident in the shallower zone of distribution of the coralligenous habitat. This correlative study did not allow us to identify any cause-effect relationship, but patterns we detected agree with those of other studies, suggesting that alterations in the environmental conditions may be the cause of the decrease in differences among assemblages developing at different depths and may lead to a higher spatial homogenization and an impoverishment of the whole subtidal system.Este estudio investiga los patrones de distribución de las comunidades algales del hábitat coralígeno en relación a la profundidad y evalúa el papel de las diferentes condiciones ambientales en la formación de estos patrones. Se han muestreado dos profundidades (30 y 40 m) en pequeñas islas y en la costa continental. Los resultados muestran diferencias entre profundidades en la estructura de las comunidades entre islas, mientras que estas diferencias no son evidentes en el continente. Además las diferencias encontradas son más evidentes a 30 metros. Este estudio correlacional no nos permite establecer ninguna relación causa-efecto; sin embargo, los patrones detectados están de acuerdo con lo observado en otros trabajos, lo que sugiere que las alteraciones en las condiciones ambientales pueden ser la causa de la disminución de las diferencias entre comunidades que se desarrollan a profundidades distintas y pueden provocar una mayor homogeneidad espacial y un empobrecimiento de la zona sublitoral

Macroalgal assemblages as indicators of the ecological status of marine coastal systems: A review

Abstract Macroalgae have been utilized as biological indicators of ecosystem health in many monitoring programs worldwide. These programs have utilized various methods to quantify macroalgal community structures. The aim of this study was to provide an overview of current progress by reviewing techniques and methods in both monitoring programs and impact evaluation studies that use macroalgal assemblage data. A total of 215 papers were selected and divided into four categories: macroalgal assemblage monitoring, macroalgal mapping, developing and employing ecological indices based on macroalgae, and developing and employing generic ecological indices including macroalgae. The number and goals of macroalgal monitoring programs are very different among geographical areas. In Europe, the recent European Union Directives led to the development of indices as tool to monitor the ecological quality of coastal systems. In other geographic regions, most studies focused on mapping the distribution of kelps or Fucales. This demonstrates the necessity to harmonize marine macroalgal monitoring, identifying common metrics and approaches in sampling design, field measurements, taxonomic resolution and data management, in order to develop standardized procedures which may allow data obtained to be compared

Comunidad de epifauna móvil asociada a las bosques de Cystoseira: comparación entre áreas invadidas y no invadidas por Lophocladia lallemandii

The study compared the structure of mobile epifaunal assemblages associated with Mediterranean Cystoseira beds between areas invaded and not invaded by Lophocladia lallemandii. A total of 150 taxa were identified: 42 Polychaeta, 78 Arthropoda, 26 Mollusca and 4 Echinodermata. Epifaunal assemblages differed between areas invaded and not invaded by Lophocladia lallemandii when the invasive species reached maximum values of cover and biomass, while differences between conditions were not significant in other periods of the year. The main differences were the greater abundance of amphipods, isopods and polychaetes in invaded areas and the greater abundance of molluscs and decapods in non-invaded areas, while richness and total abundance of organisms were not significantly different between conditions. The effects of Lophocladia lallemandii invasion on Cystoseira-associated assemblages seem to be limited to the period of vegetative growth of the alga and reversible during the period of its vegetative rest.Este estudio compara la estructura de la comunidad de macroinvertebrados móviles asociada a bosques mediterráneos de Cystoseira entre áreas invadidas por Lophocladia lallemandii y áreas no invadidas. Se identificaron un total de 150 táxones: 42 Polychaeta, 78 Arthropoda, 26 Mollusca, 4 Echinodermata. La comunidad epifaunal difirió entre áreas invadidas por Lophocladia lallemandii y áreas no invadidas cuando la Rhodophyta introducida alcanzó valores máximos de cobertura y biomasa, mientras que no presentó diferencias entre condiciones en otros períodos del año. Estas diferencias fueron principalmente debidas a una mayor abundancia de anfípodos, isópodos y poliquetos en áreas invadidas, y de moluscos y decápodos en áreas no invadidas, mientras que la riqueza y abundancia total de organismos no presentaron diferencias significativas entre condiciones. Los efectos de la invasión de Lophocladia lallemandii sobre las comunidades asociadas a Cystoseira parecen estar restringidos al período de crecimiento vegetativo del alga, siendo reversibles durante el período de pausa de crecimiento

Prostorne i vremenske varijacije pokretnih makro-beskralješnjaka u livadama Posidonia oceanica

The present study assesses the spatial and temporal distribution of motile invertebrates in Posidonia oceanica meadows located off the coast of Tuscany, in the northwestern Mediterranean Sea. A hierarchical sampling design was used to evaluate changes in composition and abundance of assemblages in relation to depth and to different periods over one year. A total of 136 taxa were determined, among them 34 Mollusca, 94 Arthropoda, 5 Annelida and 1 Echinodermata. Results of both multivariate and univariate analyses showed that the macro-invertebrate assemblage structure varied along a depth gradient but this pattern was not consistent in the two study periods. Results suggest that temporal and spatial differences in the structure of P.oceanica meadows are key drivers in determining the structure of associated macro-invertebrate assemblages, as values of richness and abundance decreased with a decrease in leaf length and shoot density.Ova studija procjenjuje prostorne i vremenske raspodjele pokretnih makro-beskralješnjaka u livadama Posidonia oceanica u blizini obale pokrajine Toskana, u sjeverozapadnom Mediteranu. Hijerarhijska uzorkovanja korištena su za procjenu promjena sastava i obilja u odnosu na dubinu i na različita razdoblja dulja od jedne godine. Ukupno 136 svojti je utvrđeno, među njima 34 Mollusca, 94 Arthropoda, 5 Annelida i 1 Echinodermata. Rezultati multivarijantne i Uni-varijabla analize pokazali su da je struktura makro-beskralješnjaka kolebala po dubini gradijenta, ali ovaj uzorak nije bio dosljedan u dva razdoblja istaživanja. Rezultati ukazuju na to da su vremenske i prostorne razlike u naselju livada P. oceanica ključni pokretači u određivanju strukture povezane sa sastavom makro-beskralješnjaka, kao što su vrijednosti bogatstva i obilja smanjene sa smanjenjem dužine lista i gustoće izdanaka

Gluten sensitivity and neurological manifestations

The authors report on six cases of gluten-sensitivity, also defined non-celiac gluten sensitivity, characterized by abdominal features (diarrhea, bloating, pain), genetic positivity for predisposition to celiac disease (DQB1* 02 in all cases; DQA1*05 in three; DQA1*02 in two, DQB1*03 in two), negative anti-t-Transglutaminase antibodies, normal mucosa on biopsy in four cases, type 1 of Marsh in one case. The subjects presented frequent central nervous system (CNS) symptoms: headache in three patients, somnolence in one, electroencephalogram aspecific alterations in three (in two of them with previous seizures), leptomeningeal cyst in one, intracranial calcification in one, cerebral gliosis in two. After a gluten-free diet, all intestinal and clinical CNS features remitted, but re-appeared after gluten reintroduction. On the basis of the neurological signs, the authors stress the relevance of immune innate system in the pathogenesis of these cases with possible subsequent evolution on immune adaptive system involvement

El sedimento como constituyente de comunidades bentónicas mediterráneas dominadas por Caulerpa recemosa var. cylindracea

Mediterranean macroalgal assemblages in areas invaded and non-invaded by Caulerpa racemosa var. cylindracea were compared and trapped sediments were characterised. Results showed that assemblages invaded by C. racemosa var. cylindracea differed greatly from non-invaded ones: encrusting and erect algae, both articulated and foliose, decreased in invaded areas, while opportunistic filamentous species increased their abundance The percentage of sediment was 7 times higher in areas invaded by C. racemosa var. cylindracea than in non-invaded areas. Characteristics of trapped sediments were similar in all the studied assemblages, while redox values were lower in the invaded ones. Results suggested that sediment constitutes an important component in C. racemosa var. cylindracea populations, probably enhancing the competitive ability of this species.Las comunidades de macroalgas mediterráneas en áreas invadidas por C. racemosa var. cylindracea y áreas no invadidas fueron comparadas y el sedimento retenido caracterizado. Los resultados muestran que las áreas invadidas por C. racemosa var. cylindracea difieren de forma marcada de las poblaciones no invadidas: algas incrustantes y erectas, articuladas y foliosas, decrecen en las áreas invadidas, mientras que las especies filamentosas oportunistas aumentan su abundancia. El porcentaje de sedimento fue siete veces mayor en áreas invadidas por C. racemosa var. cylindracea que en áreas no invadidas. Las características del sedimento atrapado fueron similares en todas las poblaciones estudiadas, mientras que los valores del potencial redox fueron menores en las zonas invadidas. Nuestros resultados sugieren que el sedimento constituye un componente importante en las poblaciones de C. racemosa, var. cylindracea, posiblemente aumentando la capacidad competitiva de esta especie

Effectiveness of different investigation procedures in detecting anthropogenic impacts on coralligenous assemblages

Coralligenous habitat is one of the most important and sensitive habitats of the Mediterranean Sea and several different sampling procedures are currently used in the ecological investigations of coralligenous assemblages. This study aimed to assess the efficacy of different methods in detecting anthropogenic impacts on coralligenous habitat. In particular, the choice of sampling methods, the level of taxonomic resolution, the sampling area, the number of replicates and the spatial scales for detecting possible impacts were evaluated. Results showed that photographic samples larger than 1800 cm2, numbers of replicates larger than 10, the use of taxa and morphological groups as assemblage descriptors, and sampling designs with a high replication at small spatial scales are a valid methodological procedure in impact evaluation studies based on coralligenous assemblages

Arrecifes coralígenos infralitorales: estructura y variabilidad espacial de las comunidades de macroalgas

Coralligenous reefs are calcareous structures edified mostly by coralline algae that characterize the circalittoral zone of the Mediterranean Sea. However, in some cases coralline algae can constitute peculiar infralittoral biogenic reefs which have been studied less than the circalittoral ones. This study aims to contribute to the knowledge of infralittoral coralligenous reefs by describing their macroalgal assemblages on a large rocky platform off the Tuscany coasts, northwestern Mediterranean Sea. To this end, a multifactorial sampling design was used to describe the structure of the assemblages and to evaluate the variability of the system at multiple spatial scales. A total of 71 macroalgal taxa were found on the coralline algae. Macroalgal assemblages were well structured, with high biodiversity values. The dominant taxa included both photophilous and sciaphilous species, guaranteeing peculiar characteristics in these assemblages, above all if compared with the typical infralittoral and circalittoral macroalgal communities of the same geographic area. The assemblages showed greater variability at a small and intermediate spatial scale than at a large scale. Although infralittoral coralligenous outcrops constitute a peculiar system, they are still poorly understood and should not only be the object of specific studies but also be included in monitoring programmes.Los arrecifes coralígenos son estructuras calcáreas edificadas principalmente por algas coralinas que caracterizan la zona circalitoral del Mar Mediterráneo. Sin embargo, en algunos casos las algas coralinas pueden constituir peculiares arrecifes biogénicos infralitorales menos investigados que los circalitorales. El estudio tiene como objetivo contribuir al conocimiento de los arrecifes coralígenos infralitorales describiendo sus comunidades de macroalgas en una gran plataforma rocosa frente a las costas de Toscana, al noroeste del mar Mediterráneo. Un diseño de muestreo multifactorial fue utilizado para describir la estructura de comunidades algales y evaluar la variabilidad del sistema en múltiples escalas espaciales. Se encontró un total de 71 taxones de macroalgas sobre las algas coralinas. Las comunidades de macroalgas estaban bien estructuradas con altos valores de biodiversidad. Los taxones dominantes incluyeron tanto especies fotófilas como esciáfilas, lo que garantizó características peculiares a estas comunidades si se comparan con las típicas comunidades de macroalgas infralitorales y circalitorales de la misma área geográfica. Las comunidades mostraron una variabilidad a pequeña e intermedia escala mayor que a gran escala espacial. Si bien los afloramientos coralígenos infralitorales constituyen un sistema peculiar, aún son poco conocidos y deberían ser objeto no solo de estudios específicos sino también incluidos en programas de monitoreo ambiental

The Seagrass effect turned upside down changes the prospective of sea urchin survival and landscape implications

Habitat structure plays an important mediating role in predator-prey interactions. However the effects are strongly dependent on regional predator pools, which can drive predation risk in habitats with very similar structure in opposite directions. In the Mediterranean Sea predation on juvenile sea urchins is commonly known to be regulated by seagrass structure. In this study we test whether the possibility for juvenile Paracentrotus lividus to be predated changes in relation to the fragmentation of the seagrass Posidonia oceanica (four habitat classes: continuous, low-fragmentation, high-fragmentation and rocks), and to the spatial arrangement of such habitat classes at a landscape scale. Sea urchin predation risk was measured in a 20-day field experiment on tethered individuals placed in three square areas 35×35 m2 in size. Variability of both landscape and habitat structural attributes was assessed at the sampling grain 5×5 m2. Predation risk changed among landscapes, as it was lower where more ‘rocks’, and thus less seagrass, were present. The higher risk was found in the ‘continuous’ P. oceanica rather than in the low-fragmentation, high-fragmentation and rock habitats (p-values = 0.0149, 0.00008, and 0.0001, respectively). Therefore, the expectation that juvenile P. lividus survival would have been higher in the ‘continuous’ seagrass habitat, which would have served as shelter from high fish predation pressure, was not met. Predation risk changed across habitats due to different success between attack types: benthic attacks (mostly from whelks) were overall much more effective than those due to fish activity, the former type being associated with the ‘continuous’ seagrass habitat. Fish predation on juvenile sea urchins on rocks and ‘high-fragmentation’ habitat was less likely than benthic predation in the ‘continuous’ seagrass, with the low seagrass patch complexity increasing benthic activity. Future research should be aimed at investigating, derived from the complex indirect interactions among species, how top-down control in marine reserves can modify seagrass habitat effects