Remobilization of Heavy Metals by Mangrove Leaves

Several studies have been carried out on heavy metal pollution in mangrove ecosystems. However, the role of mangroves in heavy metal remobilization is still relatively unknown. On one side, mangrove woody organs and soils sequester heavy metals for long time periods, but on the other hand, senescence of mangrove leaves may return these metals collected by roots to the upper layers of the soil. Here, we analyzed the concentration of chemical elements (Al, As, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sr, V, and Zn) as a function of age in mangrove leaves to understand heavy metals retention by the plant and to quantify the amounts shed with senescing leaves. In addition, we estimated metal concentrations and stocks in mangrove soils. Our results revealed that the concentration of most metals increased with leaf age, resulting in the remobilization of metals stored in soil, thereby returning metals to the upper layers of the soil during senescence of mangrove leaves. Only Cu was reabsorbed prior to shedding of leaves, a mechanism similar to that described for nutrients in mangroves globally. These results provide key data to understand mangroves role in the dynamics of heavy metals

Large mesopelagic fishes biomass and trophic efficiency in the open ocean

Xabier Irigoien et al.With a current estimate of ~1,000 million tons, mesopelagic fishes likely dominate the world total fishes biomass. However, recent acoustic observations show that mesopelagic fishes biomass could be significantly larger than the current estimate. Here we combine modelling and a sensitivity analysis of the acoustic observations from the Malaspina 2010 Circumnavigation Expedition to show that the previous estimate needs to be revised to at least one order of magnitude higher. We show that there is a close relationship between the open ocean fishes biomass and primary production, and that the energy transfer efficiency from phytoplankton to mesopelagic fishes in the open ocean is higher than what is typically assumed. Our results indicate that the role of mesopelagic fishes in oceanic ecosystems and global ocean biogeochemical cycles needs to be revised as they may be respiring ~10% of the primary production in deep waters.This research was conducted by the Malaspina 2010 Expedition project, funded by the Spanish Ministry of Economy and Competitiveness (Consolider-Ingenio 2010, CSD2008-00077). Additional financial support was provided by the Basque Country Government and by AZTI-TecnaliaPeer Reviewe

Carbon stocks and accumulation rates in Red Sea seagrass meadows

Seagrasses play an important role in climate change mitigation and adaptation, acting as natural CO2 sinks and buffering the impacts of rising sea level. However, global estimates of organic carbon (Corg) stocks, accumulation rates and seafloor elevation rates in seagrasses are limited to a few regions, thus potentially biasing global estimates. Here we assessed the extent of soil Corg stocks and accumulation rates in seagrass meadows (Thalassia hemprichii, Enhalus acoroides, Halophila stipulacea, Thalassodendrum ciliatum and Halodule uninervis) from Saudi Arabia. We estimated that seagrasses store 3.4 ± 0.3 kg Corg m−2 in 1 m-thick soil deposits, accumulated at 6.8 ± 1.7 g Corg m−2 yr−1 over the last 500 to 2,000 years. The extreme conditions in the Red Sea, such as nutrient limitation reducing seagrass growth rates and high temperature increasing soil respiration rates, may explain their relative low Corg storage compared to temperate meadows. Differences in soil Corg storage among habitats (i.e. location and species composition) are mainly related to the contribution of seagrass detritus to the soil Corg pool, fluxes of Corg from adjacent mangrove and tidal marsh ecosystems into seagrass meadows, and the amount of fine sediment particles. Seagrasses sequester annually around 0.8% of CO2 emissions from fossil-fuels by Saudi Arabia, while buffering the impacts of sea level rise. This study contributes data from understudied regions to a growing dataset on seagrass carbon stocks and sequestration rates and further evidences that even small seagrass species store Corg in coastal areas

Elbarritasun bat duten Bigarren Hezkuntzako ikasleen jarduera fisiko eta atsedenaldietan gertatzen diren egoeren azterketa

El objetivo principal de este estudio fue analizar los hábitos de práctica de actividad física, las preferencias y el tipo de actividades realizadas y las relaciones con otros compañeros y profesores en los recreos escolares en alumnos de educación secundaria con algún tipo de discapacidad. En este estudio participaron 11 alumnos con discapacidad (8 chicas y 3 chicos) de entre 14 y 21 años. Atendiendo a los resultados obtenidos, a pesar de que los participantes en este estudio afirmaban que lo que más les gusta realizar en los recreos era estar con los compañeros, jugar y pasárselo bien, en la observación directa realizada, la actividad más frecuente no fue la de jugar sino la de pasear. Por otro lado, la actividad realizada por los alumnos con discapacidad de este estudio en los recreos tuvo un carácter predominantemente socio motor. Referente a la relación de los alumnos con discapacidad con los profesores en los recreos, en mayor medida fueron los profesores quienes se acercaban a estos alumnos para entablar relación.; The aim of this study was to analyze the physical activity habits, the favorite activities during the school breaks, the nature of the activities practiced during the school breaks, the relationship of the teachers and students of the Secondary students with disabilities. In this study participated 11 secondary school students with special needs (8 girls and 3 boys). These students were aged between 14-21 years of old. According to the results of this study, even be friends, they like to play and have fun in the activities, the most practiced activity in reality he was walking through the courtyard of the students had a disability. Disability in their students during the breaks one of the most socio-engines were practiced. Regarding the relationship with teachers, most of who come to the students who were teachers.; L’objectif principal de cette étude était d’analyser les habitudes d’activité physique, les préférences et le type d’activités et les relations avec les pairs et les enseignants à la récréation de l’école des élèves du secondaire ayant une déficience. Cette étude a porté sur 11 étudiants handicapés (8 filles et 3 garçons) âgés de 14 à 21 ans. Basé sur les résultats, même si les participants à cette étude ont affirmé que la plupart de ce qu’ils aiment faire à la récréation était d’être avec ses pairs, jouer et avoir du plaisir, dans les observations directes faites, l’activité la plus commune était pas à jouer, c‘ est de se promené. D’autre part, l’activité réalisée par les élèves de l’étude avec étudiants handicapés avait un caractère principalement socio moteur. En ce qui concerne a la relation des étudiants handicapés et les enseignants à la récréation, dans une grande mesure ont été les enseignants qui s’ont approché ces étudiants à s’engager dans une relation

Identification of suspicious behaviour through anomalies in the tracking data of fishing vessels

Automated positioning devices can generate large datasets with information on the movement of humans, animals and objects, revealing patterns of movement, hot spots and overlaps among others. This information is obtained after cleaning the data from errors of different natures. However, in the case of Automated Information Systems (AIS), attached to vessels, these errors can come from intentional manipulation of the electronic device. Thus, the analysis of anomalies can provide valuable information on suspicious behaviour. Here, we analyse anomalies of fishing vessel trajectories obtained with the Automatic Identification System. The map of silence anomalies, those occurring when positioning data is absent for more than 24 h, shows that they occur more likely closer to land, observing 94.9% of the anomalies at less than 100 km from the shore. This behaviour suggests the potential of identifying silence anomalies as a proxy for illegal activities. With the increasing availability of high-resolution positioning of vessels and the development of powerful statistical analytical tools, we provide hints on the automatic detection of illegal activities that may help optimise monitoring, control and surveillance measures

Variabilidad de la biomasa del zooplankton y de su tamaño individual en un transecto costa-alta mar en el ar Catalán: relaciones con la clorofila a y las estructuras hidrográficas

The temporal and spatial changes of zooplankton and chlorophyll a concentration were studied during the warm stratification period (early June) at three stations whose traits corresponded to the coastal, frontal, and offshore-dome water conditions described for the Catalan Sea. We sampled the stations for 12 days at a frequency ranging from less than 10 to 102 h, with a spatial resolution ranging from 10 to 104 m. The objective was to determine the variability of mesozooplankton and phytoplankton (chlorophyll a) biomass, and average individual size (mass) across a coast-offshore transect in relation to the stratification conditions prevailing in the NW Mediterranean during summer. The vertical distribution of phytoplankton biomass displayed a clear deep maximum at 60 m depth except at the coastal station. This maximum exists during most of the year and is especially important during the density stratification period. It was accompanied during daylight hours by a coherent zooplankton maximum. At sunset mesozooplankton ascended and dispersed, with larger organisms from deeper layers joining the migrating community and increasing the average individual mass. The highest variability of mesozooplankton biomass, individual mass and chlorophyll a concentration occurred at the front station due to the coupling between the vertical migration of zooplankton and the particular characteristics of the front. According to the data shown, the highest variability was observed at the lowest scales.Durante el periodo de estratificación térmica (principios de junio) se estudiaron los cambios temporales y espaciales de concentración de zooplancton y clorofila a en tres estaciones cuyos rasgos corresponden a las condiciones de aguas costeras, frontal y domo central descritas para el Mar Catalán. Muestreamos las estaciones a lo largo de 12 días con una frecuencia que varió entre 10 h y 102 h, y con una resolución espacial entre 10 y 104 m. El objetivo fue determinar la variabilidad de la biomasa del fitoplancton (clorofila a) y del mesozooplancton, así como de su tamaño individual promedio a lo largo de un transecto costa-mar abierto en relación con las condiciones de estratificación térmica típicas del Mediterráneo del Noroccidental desde finales de primavera a finales de verano. La distribución vertical de la biomasa de fitoplancton mostró la existencia de un máximo profundo a 60 m de profundidad, excepto en la estación costera. Aunque cierta heterogeneidad vertical en la biomasa de fitoplancton suele observarse durante la mayor parte del año, es especialmente importante durante el período de estratificación de densidad. El máximo de fitoplancton estuvo acompañado durante las horas de luz por un máximo de zooplancton, que en la crepúsculo ascendía y se dispersaba, y al que se unían organismos de mayor tamaño procedentes de zonas más profundas, contribuyendo a aumentar la masa individual promedio. La mayor variabilidad de biomasa mesozooplanctónica, de la masa individual y de la concentración de clorofila a se observó en la estación frontal debido al acoplamiento entre la migración vertical del zooplancton y las características particulares del frente. Según los datos presentados la mayor variabilidad fue observada en las escalas espaciales y temporales más bajas

Macrozooplankton predation impact on anchovy (Engraulis encrasicolus) eggs mortality at the Bay of Biscay shelf break spawning centre

A real-time PCR based method involving a species-specific probe was applied to detect Engraulis encrasicolus eggs predation by the macrozooplank- ton community during the 2011 spawning season. Three locations along the shelf break presenting contrasting but high prey densities were sampled. A total of 840 individuals from 38 taxa of potential macrozooplankton predators were assayed for E. encrasicolus DNA presence and 27 presented at least one positive signal. Carnivorous copepods were responsible for the most predation events (66%) followed by euphausiids (16%), chaetognaths (5%), and myctophid fish (4%). Macrozooplankton predation on anchovy eggs followed a type-I functional response with daily mortalities ,4% of available prey abundance suggesting a negligible impact on the species recruitment at the shelf break spawning centre.This research was financially supported by the projects ECOGENBAY (MICINN CTM2009-13570-C02-02), funded by the Ministry of Science and Research of the Government of Spain, and BIOMAN, funded by the Department of Economic Development and Competitiveness of the Basque Government and by the European Commission

Low carbon sink capacity of Red Sea mangroves

Mangroves forests of Avicennia marina occupy about 135 km2 in the Red Sea and represent one of the most important vegetated communities in this otherwise arid and oligotrophic region. We assessed the soil organic carbon (Corg) stocks, soil accretion rates (SAR; mm y-1) and soil Corg sequestration rates (g Corg m-2 yr-1) in 10 mangrove sites within four locations along the Saudi coast of the Central Red Sea. Soil Corg density and stock in Red Sea mangroves were among the lowest reported globally, with an average of 4 ± 0.3 mg Corg cm-3 and 43 ± 5 Mg Corg ha-1 (in 1 m-thick soils), respectively. Sequestration rates of Corg, estimated at 3 ± 1 and 15 ± 1 g Corg m-2 yr-1 for the long (millennia) and short (last century) temporal scales, respectively, were also relatively low compared to mangrove habitats from more humid bioregions. In contrast, the accretion rates of Central Red Sea mangroves soils were within the range reported for global mangrove forests. The relatively low Corg sink capacity of Red Sea mangroves could be due to the extreme environmental conditions such as low rainfall, nutrient limitation and high temperature, reducing the growth rates of the mangroves and increasing soil respiration rates

Distribución espacio-temporal de la edad 1 de anchoa del golfo de Bizkaia (Engraulis encrasicolus) en el momento de puesta

To efficiently manage and maintain fish stock abundance and age structure, it is necessary to understand variability in its spatial distribution. The main objective of this study was to describe the demographic structure of the Bay of Biscay anchovy during the main spawning period based on adult samples from 15 daily egg production method surveys. The proportion of age-1 individuals was modelled using generalized additive models with a binomial distribution and a logit link in relation to geographical and environmental covariates. The possibility of obtaining different models depending on the average age-1 proportion (low or high) was also explored. In general, age-1 individuals were found in shallow waters close to the coast, especially associated with the Gironde and Adour river plumes, whereas older individuals were prevalent on the shelf break and in oceanic waters. However, in years with a high age-1 proportion the younger individuals were also dominant in oceanic waters. These results could be used for management purposes, such as defining protected areas for particular age groups.Con el fin de gestionar eficientemente la abundancia y la estructura espacial de un stock es necesario entender su distribución espacial. El objetivo principal de este trabajo es describir la estructura demográfica de la anchoa del golfo de Bizkaia durante el periodo de desove a partir de las muestras de adultos recogidas en 15 campañas del método de producción diaria de huevos. La proporción de individuos de edad 1 se modeló en función de variables geográficas y ambientales por medio de un modelo aditivo generalizado con distribución binomial y función enlace logit. Además se estudió la posibilidad de obtener diferentes modelos dependiendo de si la proporción de edad 1 promedio es baja o alta. En general, los individuos de edad 1 se encontraron en aguas poco profundas cerca de la costa, especialmente en las plumas de los ríos Garona y Adur, mientras que los individuos de mayor edad prevalecieron en el cantil y en aguas oceánicas. Sin embargo, los años con una alta proporción de edad 1, los individuos jóvenes fueron también predominantes en aguas oceánicas. Estos resultados podrían utilizarse para fines relacionados con la gestión, tales como la definición de áreas protegidas para determinados grupos de edad

A real-time PCR assay to estimate invertebrate and fish predation on anchovy eggs in the Bay of Biscay

In order to investigate the role of predation on eggs and larvae in the recruitment of anchovy (Engraulis encrasicolus), sardine (Sardina pilchardus), sprat (Sprattus sprattus) and 52 macrozooplankton taxa were assayed for anchovy remains in the gut during the 2010 spawning season using a molecular method. This real-time PCR based assay was capable of detecting 0.005 ng of anchovy DNA (roughly 1/100 of a single egg assay) in a reliable way and allowed detecting predation events up to 6 h after ingestion by small zooplankton taxa. A total of 1069 macrozooplankton individuals, 237 sardines and 213 sprats were tested. Both fish species and 32 macrozooplankton taxa showed remains of anchovy DNA within their stomach contents. The two main findings are (1) that the previously neglected macrozooplankton impact in anchovy eggs/larvae mortality is in the same order of magnitude of that due to planktivorous fishes and that, (2) the predation pressure was notably different in the two main spawning centers of Bay of Biscay anchovy. While relatively low mortality rates were recorded at the shelf-break spawning center, a higher predation pressure from both fish and macrozooplankton was exerted at the shelf one.This research was financially supported by the projects ECOGENBAY (MICINN CTM2009-13570-C02-02), funded by the Ministry of Science and Research of the Government of Spain, and BIOMAN, funded by the Department of Economic Development and Competitiveness of the Basque Government and by the European Commissio