Population biology of the sea star Anasterias minuta (Forcipulatida: Asteriidae) threatened by anthropogenic activities in rocky intertidal shores of San Matías Gulf, Patagonia, Argentina

In Patagonian coastal areas, intertidal benthic communities are exposed to extreme physical conditions. The interaction between harsh environment and anthropogenic pressure can generate changes in population biology of marine invertebrates, like density and reproduction. The oral brooding sea star Anasterias minuta is a key organism in food chains of Atlantic Patagonian rocky intertidals, hence changes on its population structure can negatively affect shore communities. We studied the population biology of A. minuta and assess the effect of environmental parameters and anthropogenic activities on its population on rocky intertidal shores of San Matías Gulf, Patagonia, Argentina. Seasonal sea surface temperature, pH, salinity, water velocity, desiccation rate, boulders density, and anthropogenic influence (tourists and octopus fishermen) were recorded. In sites with less tourist influence and high refuge, an increase in density was recorded, especially during the summer. Brooding individuals were found in fall and winter, while feeding individuals were observed in all seasons (12 different prey, mainly the molluscs Tegula patagonica and Perumytilus purpuratus). Environmental variables such as boulders density and water velocity were the most important predictor of variation in population structure. Tourism and pH were the most important variables negatively correlated with density.Fil: Arribas, Lorena Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Bagur Creta, Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentina. Grupo de Investigación y Educación en Temas Ambientales; ArgentinaFil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentina. Grupo de Investigación y Educación en Temas Ambientales; ArgentinaFil: Bigatti, Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina. Universidad Nacional de la Patagonia; Argentin

Does rock type account for variation in mussel attachment strength? A test with Brachidontes rodriguezii in the southwestern Atlantic

Mussel attachment strength varies in space and time, frequently in association with variations in wave exposure. Yet, it remains uninvestigated whether different rock types can contribute to variation in mussel attachment. Here we compared the attachment strength of the mussel Brachidontes rodriguezii between soft and hard intertidal rock substrates that are typical of coastal Buenos Aires Province, Argentina: Pampean loess cemented by calcium carbonate and orthoquartzite, respectively. Overall comparisons of mussel attachment across natural platforms of either rock type (10 loess sites and 4 orthoquartzite sites) indicated stronger mussel attachment to orthoquartzite. However, mussel attachment strength did not differ when compared across natural loess platforms and introduced orthoquartzite blocks (i.e., groins and revetments) occurring within the same site. Mussels attaching to loess showed more byssal threads than those attaching to orthoquartzite at the same site. These findings suggest, first, that rock type does not influence mussel attachment strength in our study system, secondly, that overall differences in mussel attachment strength with rock type across natural platforms in our study range are due to confounding influences of co-varying factors (e.g., wave exposure) and, finally, that mussels can increase byssus production to counteract potential substrate failure when attaching to soft, friable rock. The latter likely explains the ability of mussels to maintain relatively stable cover across rocks of contrasting hardness.Fil: Gutierrez, Jorge Luis Ceferino. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Bagur, María. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Arribas, Lorena Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

Competencia entre mitílidos en el intermareal rocoso de La Lobería, Río Negro, Argentina

Competitive interactions between individuals from a single or different species can regulate population densities and individual growth. Two mussel species, Brachidontes rodriguezii and Perumytilus purpuratus coexist in the rocky intertidal zone of La Lobería, Río Negro Province, Argentina. The aim of this study was to analyse the effect of intra- and interspecific competition growth and mortality of both bivalve species. An experiment was conducted to evaluate the intra- and interspecific competition using asbestos cement plates of 10 x 10 cm varying mussel densities. The width of P. purpuratus showed a significant increase in presence of B. rodriguezii. There also was a non-significant trend toward decreasing B. rodriguezii size with increasing density of conspecifics and when coexisting with P. purpuratus. Mortality of B. rodriguezii and P. purpuratus did not differ significantly among treatments. Limited supply of P. purpuratus larvae or local tidal conditions that differentially affect each species could be leading to weak competition between both mussel species, thus allowing their coexistence.Las interacciones competitivas entre individuos de una misma o distintas especies pueden regular las densidades poblacionales y el crecimiento individual. Dos especies de mitílidos, Brachidontes rodriguezii y Perumytilus purpuratus, coexisten en el intermareal rocoso de La Lobería, provincia de Río Negro, Argentina. El objetivo de este trabajo fue analizar el efecto de la competencia intra- e interespecífica sobre el crecimiento y la mortalidad de ambas especies de bivalvos. Se realizó un experimento para evaluar la competencia intra- e interespecífica utilizando placas de fibrocemento de 10 x 10 cm variando las densidades de mitílidos. El ancho de P. purpuratus mostró un aumento significativo ante la presencia de B. rodriguezii. Se observó también una tendencia no significativa hacia la disminución de tallas de B. rodriguezii al aumentar la densidad de coespecíficos y al coexistir con P. purpuratus. La mortalidad de B. rodriguezii y P. purpuratus no mostró diferencias significativas entre tratamientos. Un limitado arribo de larvas de P. purpuratus o condiciones locales del intermareal que benefician diferencialmente a las especies podrían llevar a que los efectos de competencia entre estas sean débiles, haciendo posible la coexistencia.Fil: Arribas, Lorena Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Bagur Creta, Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Soria, Sabrina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Gutierrez, Jorge Luis Ceferino. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales; Argentina. Estación Biológica Las Brusquitas. Grupo de Investigación y Educación en Temas Ambientales; ArgentinaFil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Estación Biológica Las Brusquitas. Grupo de Investigación y Educación en Temas Ambientales; Argentin

Dátiles de mar: Mejillones que perforan las rocas costeras

A diferencia de sus famosos homónimos producidos por palmeras, los dátiles de mar son animales. Se trata de unos moluscos bivalvos poco conocidos que miden unos pocos centímetros y se distinguen por su capacidad de horadar cavidades en rocas calizas de la zona intermareal. Viven en ellas protegidos de predadores, del embate de olas y de la desecación que los amenaza cuando se retiran las aguas. No perforan las rocas en forma mecánica sino química, pues secretan un ácido que disuelve el carbonato de calcio. Su acción hace que a menudo se los considere perjudiciales, aunque también contribuyen al incremento de la biodiversidad del ambiente costero. Una especie de ellos, llamada Lithophaga patagonica, es muy abundante en las costas argentinas.Fil: Bagur Creta, Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; ArgentinaFil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; ArgentinaFil: Arribas, Lorena Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Gutierrez, Jorge Luis Ceferino. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Wave action limits crowding in an intertidal mussel

Intraspecific competition for space is generally invoked as the chief process limiting crowding in sessile or highly sedentary marine invertebrates. However, the mechanisms by which high conspecific density induces individual removal or mortality, in turn restraining crowding in these organisms, generally remain uninvestigated. Here we illustrate that mussel crowding in a southwestern Atlantic rocky intertidal shore is limited by a combination of wave action and space limitation. Brachidontes rodriguezii mussel beds at this site occur primarily as a single layer of individuals because wave forces remove multilayered mussel hummocks quickly after they develop. Mussels in hummocks show lower attachment strength than those in the single-layered matrix. Accordingly, wave conditions associated with the passage of cold fronts (i.e. transition zones from warm air to cold air accompanied by moderate to strong winds and wave action, with 7 d average recurrence times based on historical weather data) cause detectable mussel dislodgment in a high proportion of hummocks but have virtually no impact on single-layered areas. Since wave action is the proximate cause of mussel dislodgment, upper limits to crowding in this species would not be fixed to a particular level of space occupation (i.e. as predictable from inter-individual interference alone) but would be variable in space and time depending on wave exposure. This example suggests a mechanism of population control where the impact of a physical factor on population size is larger at higher population density and supports early hypotheses about the occurrence of density-dependent population control by physical factors when the availability of safe sites is limiting.Fil: Gutierrez, Jorge Luis Ceferino. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Cary Institute of Ecosystem Studies; Estados UnidosFil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Bagur Creta, Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Arribas, Lorena Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Soria, Sabrina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

A facultative mutualism between habitat-forming species enhances the resistance of rocky shore communities to heat waves

Heat waves have increased in frequency, duration, and magnitude in recent decades, causing mass mortality events in terrestrial and aquatic ecosystems. Arguably, mass mortalities of habitat-forming organisms – i.e., dominant sessile organisms that define habitats via their own physical structure – would be amongst the most dramatic impact of heat waves because of their negative, cascading consequences on their associated biodiversity. However, the resistance of habitat-forming organisms to heat waves can be enhanced if they associate with secondary habitat formers able to tolerate and modulate extreme heat levels. Here we show that a seaweed of the Porphyra/Pyropia (P/P) clade can shield primary habitat-forming mussels, Brachidontes rodriguezii, from the impacts of extreme temperatures in a southwestern Atlantic rocky intertidal shore. By means of P/P removal experiments and surveys, we illustrate that P/P cover (a) buffers temperatures in the understory mussel beds during daytime air exposure periods in the summer, (b) reduces mussel mortality and leads to increased mussel body condition during warm summer periods, and (c) can prevent mass mortality of mussels during the course of a heat wave. Additionally, by means of a mussel removal experiment we illustrate that mussel cover is critical for P/P establishment, which is in consonance with the remarkably higher P/P densities and cover observed in mussel beds relative to exposed rock surfaces across a ~70 km coastal range. Collectively, these findings reveal a facultative mutualism where mussels provide a favorable substrate for P/P colonization and P/P attenuates heat mediated mortality on mussels. The ability of P/P to enhance the resistance of mussel beds to extreme heat events and the occurrence of similar P/P-mussel associations during spring-summer at globally dispersed sites suggests a widespread importance of P/P for the stability of mussel beds and their associated communities under warming climates.Fil: Gutierrez, Jorge Luis Ceferino. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina. Estación Biológica las Brusquitas; ArgentinaFil: Bagur D'andrea, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Estación Biológica las Brusquitas; ArgentinaFil: Lorenzo, Rodrigo Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. University Of Plymouth; Reino UnidoFil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Estación Biológica las Brusquitas; Argentin

A facultative mutualism between habitat-forming species enhances the resistance of rocky shore communities to heat waves

Heat waves have increased in frequency, duration, and magnitude in recent decades, causing mass mortality events in terrestrial and aquatic ecosystems. Arguably, mass mortalities of habitat-forming organisms – i.e., dominant sessile organisms that define habitats via their own physical structure – would be amongst the most dramatic impact of heat waves because of their negative, cascading consequences on their associated biodiversity. However, the resistance of habitat-forming organisms to heat waves can be enhanced if they associate with secondary habitat formers able to tolerate and modulate extreme heat levels. Here we show that a seaweed of the Porphyra/Pyropia (P/P) clade can shield primary habitat-forming mussels, Brachidontes rodriguezii, from the impacts of extreme temperatures in a southwestern Atlantic rocky intertidal shore. By means of P/P removal experiments and surveys, we illustrate that P/P cover (a) buffers temperatures in the understory mussel beds during daytime air exposure periods in the summer, (b) reduces mussel mortality and leads to increased mussel body condition during warm summer periods, and (c) can prevent mass mortality of mussels during the course of a heat wave. Additionally, by means of a mussel removal experiment we illustrate that mussel cover is critical for P/P establishment, which is in consonance with the remarkably higher P/P densities and cover observed in mussel beds relative to exposed rock surfaces across a ~70 km coastal range. Collectively, these findings reveal a facultative mutualism where mussels provide a favorable substrate for P/P colonization and P/P attenuates heat mediated mortality on mussels. The ability of P/P to enhance the resistance of mussel beds to extreme heat events and the occurrence of similar P/P-mussel associations during spring-summer at globally dispersed sites suggests a widespread importance of P/P for the stability of mussel beds and their associated communities under warming climates

Cirripedios invasores aceleran la recuperación de bancos de mejillines nativos

El mejillín, Brachidontes rodriguezii, es un bivalvo epibentónico que ocupa hasta el 90% de la superficie en la zona media de los intermareales rocosos bonaerenses. El cirripedio, Balanus glandula, es una especie no nativa detectada en la década del 60 en Mar del Plata y que se ha expandido a lo largo de la costa argentina. La cobertura de los mejillines suele ser discontinua en las costas rocosas, ya que el desprendimiento causado por la acción de las olas y temperaturas extremas. Es en estos parches de roca expuesta donde los cirripedios reclutan mayormente. En este trabajo se evaluó experimentalmente el rol del cirripedio sobre la sucesión de especies tras la remoción experimental de la cubierta de mejillines en el intermareal rocoso de Playa Grande (Mar del Plata, 38°01' S-57°31' O). Con tal fin, se removió la cobertura del mejillín en doce áreas cuadrangulares de 25 x 25 cm 5 semanas antes del reclutamiento de cirripedios. Una vez que reclutaron, se removieron todos los reclutas en la mitad de las unidades y se las mantuvo sin cirripedios, mientras queen el resto de las unidades se permitió el desarrollo de los mismos. Tras 16 meses, se observó que la recolonización por mejillines fue mayor en los controles con cirripedios que en los tratamientos sin cirripedios. Los resultados indican que la presencia del cirripedio facilita el restablecimiento de los mejillines en las áreas donde hubo un desprendimiento.Fil: Soria, Sabrina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Gutierrez, Jorge Luis Ceferino. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaXXIX Reunión Argentina de EcologíaOnlineArgentinaAsociacion Argentina de Ecologí

Enhanced weathering and erosion of a cohesive shore platform following the experimental removal of mussels

The organisms inhabiting intertidal platforms can affect their weathering and erosion rates. Research on biotic influences on platform integrity has traditionally emphasized the role of bioeroders (i.e., organisms that scrap or bore into platforms via mechanical and chemical means). Yet, recent studies illustrate that covers of sessile organisms on the surfaces of intertidal platforms can have bioprotective effects by reducing the efficacy of physical weathering and erosion agents. Eroding cliffs fronted by cohesive shore platforms are a pervasive feature along the continental Argentinean coastline (37–52°S). In this study, we investigated how mussel (Brachidontes rodriguezii) cover mediates weathering and erosion of a cohesive, consolidated silt platform at Playa Copacabana (5 km north of Miramar, Buenos Aires Province; 38° 14′ S, 57° 46′ W). By means of mussel removal experiments, we found that mussel cover attenuates variations in platform surface temperatures, enhances moisture retention during low tide, reduces rates of salt crystallization within the pores of the platform material, and attenuates hydrodynamic forcing on the platform surface. Mussel removal also led to a 10% decrease in surface hardness and a 2-mm reduction in platform height after 5 months. Collectively, our findings indicate that mussel beds limit substrate breakdown via heating-cooling, wetting-drying, and salt crystallization and provide some of the first experimental field evidence for the direct impacts of biotic cover on platform erosion. As intertidal platforms protect the cliffs behind from the hydraulic impact of waves, which may be enhanced with future sea-level rise, we posit that the protection of platforms by mussels indirectly moderates coastline retreat, especially on soft cohesive shores.Fil: Gonzalez, Juliana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Coombes, Martin A.. University of Oxford; Reino UnidoFil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Isla, Federico Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Soria, Sabrina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Gutierrez, Jorge Luis Ceferino. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentin

Comparison of DNA Extraction Protocols and Molecular Targets to Diagnose Tuberculous Meningitis

Tuberculous meningitis (TBM) is a severe form of extrapulmonary tuberculosis. The aims of this study were to evaluate in-house molecular diagnostic protocols of DNA extraction directly from CSF samples and the targets amplified by qPCR as an accurate and fast diagnosis of TBM. One hundred CSF samples from 68 patients suspected of TBM were studied. Four DNA extraction techniques (phenol-chloroform-thiocyanate guanidine, silica thiocyanate guanidine, resin, and resin with ethanol) were compared and CSF samples were used to determine the best target (IS6110, MPB64, and hsp65 KDa) by qPCR. The extraction protocol using the phenol-chloroform-thiocyanate guanidine showed the best results in terms of quantification and sensitivity of PCR amplification, presenting up to 10 times more DNA than the second best protocol, the silica guanidine thiocyanate. The target that showed the best result for TBM diagnosis was the IS6110. This target showed 91% sensitivity and 97% specificity when we analyzed the results by sample and showed 100% sensitivity and 98% specificity when we analyzed the results by patient. The DNA extraction with phenol-chloroform-thiocyanate guanidine followed by IS6110 target amplification has been shown to be suitable for diagnosis of TBM in our clinical setting