Movimientos verticales diarios de larvas de peces en estadío pre-flexión asociados a las praderas de Posidonia oceanica

Habitat complexity is a strong determinant of fish assemblage structure. Enhanced food resources and protection from predators are generally considered the main benefits of vegetated areas. We investigated the diel and vertical movements of preflexion fish larvae within and above the leaf canopy of Posidonia oceanica to determine if it acts as an important habitat for larval stage fish. Samples were taken with moored plankton nets during the night and day at two depths (13 and 15 m) over five consecutive days in July 2000 in the Marine Protected Area off Tabarca Island (Spain, SW Mediterranean Sea). In total, 353 fish larvae were captured. The most abundant taxa were Sardinella aurita, Sparidae, Engraulis encrasicolus and Gobiidae. Sparidae were more abundant within the leaf canopy during the day but increased in waters 2 m above the canopy at night. In contrast, Sardinella aurita were present throughout the entire water column during both the day and night. We conclude that the P. oceanica leaf canopy is important as a transitional shelter for the early stage larvae of some demersal fish species.El tipo de hábitat determina la estructura del poblamiento larvario de peces. Los principales beneficios que proporciona un hábitat con vegetación son el incremento de las fuentes de alimento y una mayor protección frente a los predadores. Este estudio se ha centrado en praderas de Posidonia oceanica para evaluar su papel como zonas de refugio, función que ha sido poco estudiada. Este trabajo se ha llevado a cabo en la Reserva Marina de Tabarca (España, SW Mar Mediterráneo). Las muestras se recolectaron con redes de plancton fijas en periodos diurnos y nocturnos, y a dos profundidades (13 y 15 m), durante 5 días consecutivos en el mes de Julio de 2000. Se capturaron 353 larvas y 256 fueron identificadas. Los taxones más abundantes fueron S. aurita, Sparidae, Engraulis encrasicolus y Gobiidae. Sparidae dominó al nivel de las hojas de la pradera durante el día, incrementando su presencia en la columna de agua durante la noche; mientras que la S. aurita se encontró a lo largo de toda la columna de agua en los dos periodos estudiados. Nuestro estudio confirma el papel de las praderas de P. oceanica como zona de refugio transitoria para los primeros estadios de larvas de de peces, aunque limitado a algunas especies demersales.

Ictioplancton asociado a praderas de Posidonia oceanica durante la época estival en la reserva marina de Tabarca

El hábitat es un factor decisivo en la supervivencia de los estadios tempranos. Los objetivos de este trabajo se centran en describir el poblamiento ictioplantónico de la pradera de P. oceanica en la reserva marina de Tabarca, así comosu comportamiento según el periodo día-noche. Se calaron redes fijas a nivel de P. oceanica y a 2 m por encima de ella durante cinco días en julio de 2000. Se capturaron 353 larvas. Las familias más abundantes fueron Clupeidae, Sparidae, Engraulidae y Gobbidae, representando el 31%, el 27%, el 11% y el 6%, respectivamente. Especies de pequeño tamaño presentan capacidad de seleccionar el hábitat. Concluimos que la pradera de P. oceanica es un factor determinante de la estructura del poblamiento larvario de especies demersales. Palabras clave: Larvas de peces, Fanerógamas marinas, Refugio, Redes fijas de plancton.Habitat complexity plays a key role in survival in early stages of fish larvae. We investigated fish larvae assemblage and its relation with P. oceanica seagrass at the Tabarca Island Marine Reserve. Samples were taken using moored plankton nets at two depths (0 and 2 m from P. oceanica meadow) over five consecutive days in July 2000. Three hundred and fifty-three larvae were captured. The most abundant families were Clupeidae (31%), Sparidae (27%), Engraulidae (11%) and Gobiidae (6%). We observed that small fish larvae were able to select nursery areas. We conclude that the P. oceanica leaf canopy is a major factor in structuring the larval fish assemblages of some demersal species. Key words: Fish larvae, Seagrasses, Habitat shelter, Moored plankton nets.El hábitat es un factor decisivo en la supervivencia de los estadios tempranos. Los objetivos de este trabajo se centran en describir el poblamiento ictioplantónico de la pradera de P. oceanica en la reserva marina de Tabarca, así comosu comportamiento según el periodo día-noche. Se calaron redes fijas a nivel de P. oceanica y a 2 m por encima de ella durante cinco días en julio de 2000. Se capturaron 353 larvas. Las familias más abundantes fueron Clupeidae, Sparidae, Engraulidae y Gobbidae, representando el 31%, el 27%, el 11% y el 6%, respectivamente. Especies de pequeño tamaño presentan capacidad de seleccionar el hábitat. Concluimos que la pradera de P. oceanica es un factor determinante de la estructura del poblamiento larvario de especies demersales. Palabras clave: Larvas de peces, Fanerógamas marinas, Refugio, Redes fijas de plancton

Androgen action via testicular arteriole smooth muscle cells is important for leydig cell function, vasomotion and testicular fluid dynamics

Regulation of blood flow through the testicular microvasculature by vasomotion is thought to be important for normal testis function as it regulates interstitial fluid (IF) dynamics which is an important intra-testicular transport medium. Androgens control vasomotion, but how they exert these effects remains unclear. One possibility is by signalling via androgen receptors (AR) expressed in testicular arteriole smooth muscle cells. To investigate this and determine the overall importance of this mechanism in testis function, we generated a blood vessel smooth muscle cell-specific AR knockout mouse (SMARKO). Gross reproductive development was normal in SMARKO mice but testis weight was reduced in adulthood compared to control littermates; this reduction was not due to any changes in germ cell volume or to deficits in testosterone, LH or FSH concentrations and did not cause infertility. However, seminiferous tubule lumen volume was reduced in adult SMARKO males while interstitial volume was increased, perhaps indicating altered fluid dynamics; this was associated with compensated Leydig cell failure. Vasomotion was impaired in adult SMARKO males, though overall testis blood flow was normal and there was an increase in the overall blood vessel volume per testis in adult SMARKOs. In conclusion, these results indicate that ablating arteriole smooth muscle AR does not grossly alter spermatogenesis or affect male fertility but does subtly impair Leydig cell function and testicular fluid exchange, possibly by locally regulating microvascular blood flow within the testis

Low satisfaction and failed relational coordination among relevant stakeholders in Spanish Mediterranean marine protected areas

Marine protected areas (MPAs) are a conservation tool that are increasingly commonplace around the world. MPAs have the potential to benefit both ecosystems and human communities if well-designed and implemented. Achieving effective implementation and governance of MPAs, however, is complicated because they deal with systems that overlap with both non-human environments and human economies and societies. As a result, MPA success is thought to be primarily dependent on socioeconomic factors, particularly the behavior of stakeholder groups involved in the MPAs. Using the theory of relational coordination, we designed surveys that we delivered to members of four stakeholder groups implicated in five MPAs in the Spanish Mediterranean to investigate their habits of inter- and intra-group communication and relations. Relational coordination posits that high-quality communication and relations results in positive stakeholder behaviors and an effective system, which makes it a useful tool to investigate the effectiveness of the MPAs involved in this study. Our results demonstrate that a high degree of relational coordination leads to higher satisfaction on the part of the participants in the system. The exploratory model constructed here also supports the notion that each stakeholder group adopts particular beliefs and behaves in particular ways in terms of relational coordination and satisfaction. We found patterns that indicated poor communication and relations amongst the four stakeholder groups, which in turn has grave implications for management outcomes of these MPAs. Cumulatively, these conditions could precipitate management failure. To remedy these concerns, we recommend establishing channels of communication between the four stakeholder groups, and investigating means to cultivate good relations amongst these groups. Doing so will help assure management success

Tertiary remagnetization of Paleozoic rocks from the Eastern Cordillera and sub-Andean Belt of Bolivia

Paleomagnetic samples were collected from 98 sedimentary horizons in eight different Devonian to Permian sedimentary units at eight localities in the Eastern Cordillera and the sub-Andean Belt of Bolivia. For 77 sites, thermal demagnetization allowed determination of a characteristic magnetization (ChRM) with site-mean 95% confidence limit, α95, ≤15°. The ChRM is carried predominantly or entirely by hematite. Fold and reversal tests from two of the sampled localities indicate that the characteristic magnetization is synfolding, likely acquired during the earliest stages of deformation. Additionally, a modified conglomerate test at one locality and the nearly uniform direction of ChRM across the Devonian to Permian age units clearly reveals the secondary nature of the characteristic magnetization. Finally, the ChRM directions are discordant from any expected Paleozoic directions. Paleomagnetic poles calculated from the ChRM directions fall near the Cenozoic portion of the apparent polar wander path for South America. We interpret these observations to indicate widespread chemical remagnetization of these Paleozoic strata during, but prior to completion of, Cenozoic Andean folding

Habitat colonisation by amphipods : comparison between native and alien algae

Invasion of algal habitat by the alien alga Caulerpa racemosa results in changes to habitat structure, part of which may be due to accumulation of large amounts of detritus. In turn, such changes lead to alterations in the assemblage structure of associated invertebrates. The present study was aimed at testing the hypotheses that (i) invasion by C. racemosa will influence the assemblage structure of amphipods associated with vegetated habitats, since colonisation by the invertebrates will differ between native algal habitat and habitat invaded by the alien alga, and (ii) differences in colonisation are mainly due to accumulation of detritus by the alien alga. To test these hypotheses, field experiments on habitat colonisation were undertaken at two sites within each of two Mediterranean localities (Malta and Spain). Using mesh bags, 3 different habitats were introduced at each site: habitat with the native alga Halopteris scoparia, habitat with C. racemosa, and an artificial habitat resembling algal habitat. Additionally, empty mesh bags were deployed as controls. Mesh bags containing plant material were defaunated prior to deployment. For each of the three habitat types, three supplement treatments were used: (i) no detritus, (ii) low detritus, and (ii) high detritus. The bags were placed on a rocky substratum at a water depth of 4.5–5 m for a period of 14 days, after which they were collected and the amphipod assemblage was assessed. The results showed that, overall, amphipod species richness and abundance were higher in bags containing H. scoparia but some amphipods exhibited a broad capability to colonize new habitat such as C. racemosa. Accumulation of detritus by the alien alga may play an important role but small-scale physical or biological habitat features can affect its ecological role.peer-reviewe

An Ecosystem Approach to the Role of Fish Farming in Coastal Areas

Coastal ecosystems put up most of the impacts from human activities in the sea. Generally, assessment based on a unispecific ecological group and/or habitat reflects only a fraction of what is happening in the ecosystem, and usually it is biased by the spatial and temporal variability at small scales. This is more evident when several human activities co-exist in the same area and interact synergically among them and with the natural structure and dynamics of the ecosystem. An ecosystemic assessment can combine several ecological groups, habitats, processes and/or activities, and offer a more holistic picture about the structure and dynamics of the considered coastal area.This study was partially funded by Spanish Ministry of Science Grant (Project FATFISH CTM2009-14362-C02-01). JTBS thanks to Conselleria d'Educació, Generalitat Valenciana, for financing the visit to La Paz during 2012. FAS thanks support to visit the University of Alicante during 2013

Aspectos estratigráficos y petrográficos del volcanismo jurásico de la costa sur peruana (departamentos de Moquegua y Tacna)

Petrographycal aspects of jurassic volcanic deposits of the Peruvian south coast are analyzed in the present work, which correspond to andesites and basalts corresponding to the Chocolate Formation and Chert stratified facies of the Guaneros Formation, the volcanic ones belong to a system of volcanic arc whereas deposits of the Guaneros Formation are signal of a cortical thinning for this period in the Peruvian South margin.Aspectos petrográficos de los depósitos volcánicos jurásicos de la costa sur peruana son analizados en el presente trabajo los cuales corresponden a andesitas y basaltos correspondientes a la Formación Chocolate y facies estratificadas de chert de la Formación Guaneros, los volcanicos pertenen a un sistema de arco volcánico mientras que depósitos de la Formación Guaneros son señal de un adelgazamiento cortical para este periodo en la margen sur peruana

Seasonal patterns and diets of wild fish assemblages associated with Mediterranean coastal fish farms

Fish are attracted to floating structures, including coastal cage fish farms, sometimes in dense aggregations. To understand better the influence of aquaculture on wild fish stocks, we carried out seasonal visual censuses around three southwestern Mediterranean farms over 2 years to assess the temporal patterns of the aggregated fish assemblage. In addition, we analysed the diet of the five most abundant species. Aggregations around all farms were large throughout the year, although species composition and abundance differed among farms and seasons. Fish farms are attractive habitats for certain species of wild fish in specific seasons. Adult fish of reproductive size dominated the assemblages, and stomach content analysis revealed that 66–89% of fish of the five most abundant taxa had consumed food pellets lost from the cages. We estimated that wild fish consume up to 10% of the pellets used at farms, indicating that food is a key attractant. Regional monitoring of farm-associated wild fish assemblages could aid management of the interaction of aquaculture and wild fish resources, because changes in feeding behaviour may have consequences for fish populations and local fisheries.The study forms part of the ACUFISH project (Unidad de Biología Marina, University of Alicante) and was funded by Spanish Ministry of Science grant MYCT-REN2003-00794

Caprellid assemblages (Crustacea: Amphipoda) in shallow waters invaded by Caulerpa racemosa var. cylindracea from southeastern Spain

Growth of the invasive algae Caulerpa racemosa var. cylindracea in shallow habitats may inXuence the faunal assemblage composition. We studied its eVects on caprellid assemblages associated with shallow-water habitats of hard and soft bottoms from the SE Iberian Peninsula (native rocky-bottom algae, C. racemosa from hard and soft bottoms, and Caulerpa prolifera, Cymodocea nodosa and Posidonia oceanica from soft bottoms). Samples were taken in two diVerent sampling periods (September 2004 and March 2005). A total of seven caprellid species were identiWed, with important diVerences in their distribution in diVerent habitats. Total abundance of caprellids was very high in March on native algae on hard bottoms, and on C. racemosa on both soft and hard bottoms. On both hard and soft bottoms, abundances of Caprella hirsuta recorded from C. racemosa were low. On the other hand, a higher abundance of other species, namely C. acanthifera, C. santosrosai, Phtisica marina and Pseudoprotella phasma, was recorded from C. racemosa. The results indicate that C. racemosa may have a positive inXuence on some caprellid species, while seasonal changes are also evident. It is concluded that introduced C. racemosa may serve as a new habitat, promoting and maintaining caprellid populations in shallow Mediterranean habitats.Ministerio de Educación y Ciencia de España y fondos FEDER de la Unión Europea. CGL2007-60044/BOSConsejería de Innovación, Ciencia y Empresa de la Junta de Andalucía. P07-RNM-0252