Fish bile as a biomarker for metal exposure

Fish accumulate several trace elements in muscle, gills and liver, however studies also indicate that metals can be excreted through bile. Since metal contamination leads to modifications in bile composition, biliary excretion offers an alternative way to evaluate the presence of trace-elements. Bile is easier to obtain than other organs and presents a simpler matrix, making it easier for chemical pre-treatment. To verify if bile can be useful as a biomonitoring tool for metal contamination, liver and bile trace element concentrations were determined and correlated. The Artificial Neural Networks statistical technique was used to verify if liver trace-element quantification could be substituted by bile analysis. Results show that significant correlations were obtained between trace elements in bile and liver and the ANN validated the hypothesis that certain trace-elements in bile could be utilized instead of liver trace-elements. Further studies in this field are of interest to further validate this biomarker.     

Differential gene expression in oyster exposed to sewage

In order to investigate the influence of domestic sewage on the gene expression of Pacific oysters Crassostrea gigas, suppression subtractive hybridization (SSH) method was employed. Oysters were sampled at a farming area and, after 10 days of acclimation in the laboratory, were exposed to untreated domestic sewage diluted 33% for 48 h. Gills of male oysters were excised for total RNA extraction. mRNA was purified and the differential gene expression was analyzed by SSH. We obtained 61 cDNA sequences but only 15 were identified, which includes fatty acid binding protein, multidrug resistance protein, omega glutathione S-transferase, cytochrome P450 isoform CYP356A1, among others. The identified genes are associated with different metabolic functions like biotransformation, membrane transport, aerobic metabolism and translational machinery, evidencing the potential toxic effects elicited by these effluents.     

Effect of outplanting time on commercial cultivation of kelp <Emphasis Type="Italic">Laminaria saccharina</Emphasis> at the southern limit in the Atlantic coast,N.W. Spain

The aim of the study is to examine the influence of the outplanting time on the cultivation of the kelp Laminaria saccharina in the northwestern Spain, close to its southern limit of distribution in the North Atlantic coast. We compared two L. saccharina cultures outplanted in February and December. We found that the starting time of outplanting affects to the yield and the substantiality value, as well as the growth rate. The yield, the substantiality value and the growth rates of L. saccharina sporophytes obtained for the trial outplanted in December were significantly higher than those in February. These results can be mainly explained by the effect of temperature on the growth of L. saccharina sporophytes during cultivation. On the other hand, our results show that even in the southern limit of distribution of L. saccharina, the cultivation of this species was very profitable in high yield and quality.     

Groundwater salinization in the Azores archipelago (Portugal)

Groundwater salinization in coastal regions causes severe constraints to water supply and economic losses to society worldwide. In the Azores archipelago, groundwater abstraction in wells drilled in coastal aquifers is very important for water supply, and quality problems have been reported. Therefore, a groundwater chemistry dataset from wells was compiled to study groundwater salinization in these aquifers. Waters are mainly of the Na–Cl type, presenting a slightly acidic to slightly alkaline character, with a pH between 5.63 and 8.50 (median 7.40). Electrical conductivity measurements range from 127 to 9,670 μS/cm (median 862), suggesting highly variable mineralization, with higher values observed on Santa Maria, São Miguel, Pico, Graciosa, and São Jorge islands. The major-ion composition reflects the contribution of seawater to the groundwater compositional evolution, which is essentially explained by seawater intrusion into wells. In many samples, exchange reactions of Na⁺ + K⁺ for Ca²⁺ + Mg²⁺ are associated with salinization. The seawater fraction in groundwater composition reaches a maximum of 22.5%. These results are extremely challenging to water managers in the Azores because failure to comply with national water quality regulations and with European Union groundwater directive requirements often occurs.     

Advancing tsunami risk assessment by improving spatio-temporal population exposure and evacuation modeling

Tsunamis are among the most destructive and lethal of coastal hazards. These are time-specific events, and despite directly affecting a narrow strip of coastline, a single occurrence can have devastating effects and cause massive loss of life, especially in urbanized coastal areas. In this work, in order to consider the time dependence of population exposure to tsunami threat, the variation of spatio-temporal population distribution in the daily cycle is mapped and analyzed in the Lisbon Metropolitan Area. High-resolution daytime and nighttime population distribution maps are developed using ‘intelligent dasymetric mapping,’ that is, applying areal interpolation to combine best-available census data and statistics with land use and land cover data. Workplace information and mobility statistics are considered for mapping daytime distribution. In combination with a tsunami hazard map, information on infrastructure, land use and terrain slope, the modeled population distribution is used to assess people’s evacuation speed, applying a geospatial evacuation modeling approach to the city of Lisbon. The detailed dynamic population exposure assessment allows producing both daytime and nighttime evacuation time maps, which provide valuable input for evacuation planning and management. Results show that a significant amount of population is at risk, and its numbers increase dramatically from nighttime to daytime, especially in the zones of high tsunami flooding susceptibility. Also, full evacuation can be problematic in the daytime period, even if initiated immediately after a major tsunami-triggering earthquake. The presented approach greatly improves tsunami risk assessment and can benefit all phases of the disaster management process.     

Sediment transport measurements with tracers in very low‐energy beaches

This study investigates sediment transport at a very low‐energy backbarrier beach in southern Portugal, from a spring‐to‐neap tide period, during fair‐weather conditions. Rates and directions of transport were determined based on the application of fluorescent tracer techniques. Wind and currents were collected locally, whereas the dominant small and short‐period wind waves were characterized using a morphodynamic modelling system coupling a circulation model, a spectral wave model, and a bottom evolution model, well validated over the study area. For the recorded conditions sediment transport was small and ebb oriented, with daily transport rates below 0.02 m³ day^‐1. Tidal currents (mainly ebb velocities) were found to be the main causative forcing controlling sediment displacements. Transport rates were higher during spring tides, tending towards very small values at neap tides. Results herein reported points towards the distinction between tracer advection and tracer dispersion in this type of environment. Transport by advection was low as a consequence of the prevailing hydrodynamic conditions (H_s < 0.1 m, and max. current velocity of 0.5 m s^‐1) and the tracer adjustment to the transport layer, whereas dispersion was relatively high (few metres per day). Tracer techniques allowed distinguishing the broad picture of transport, but revealed the need for refinement in this type of environments (bi‐directional forcing by ebb and flood cycles). Copyright © 2012 John Wiley & Sons, Ltd.     

Large‐scale connectivity of Grapsus grapsus (Decapoda) in the Southwestern Atlantic oceanic islands: integrating genetic and morphometric data

The degree of connectivity among island populations can influence their demography and affect their level of genetic differentiation. In this study we investigated genetic and morphometric differences among four populations of Grapsus grapsus (Linnaeus 1758), in Saint Peter and Saint Paul Archipelago (0°55′ N, 29°20′ W), Fernando de Noronha Archipelago (3°50′ S, 32°24′ W), Rocas Atoll (3°50′ S, 33°49′ W) and Trindade Island (20°30′ S, 29°20′ W) from 2003 to 2011. Morphometric results indicated the existence of two distinct groups based on the morphology of their chelae (Trindade Island/Saint Peter and Saint Paul Archipelago versus Fernando de Noronha/Rocas Atoll). In addition, genetic variation in a fragment of the mitochondrial control region revealed substantial differentiation between Trindade and the other islands, with Trindade Island showing only exclusive haplotypes. The congruence of the genetic and morphologic analyses suggests the occurrence of a divergent population in Trindade Island as well as high connectivity among the three remaining equatorial islands. This is the first study to assess the level of morphologic differentiation and genetic connectivity of a species among all four Southwestern Atlantic oceanic islands. Our results provide valuable insight into understanding connectivity through surface ocean currents and suggest that the unstable current system of this area could be responsible for different dispersal patterns. We also suggest that the design of Brazilian marine protected areas should be adjusted to provide stronger protection for Trindade Island as it harbors unique genetic and morphologic variation in G. grapsus.     

Plankton biomass and larval fish abundance prior to and during the El Niño period of 1997-1998 along the central Pacific coast of México

The temporal and spatial distributions of zooplankton biomass and larval fish recorded during 27 months (December 1995-December 1998) off the Pacific coast of central México are analyzed. A total of 316 samples were obtained by surface (from 40-68 to 0 m) oblique hauls at 12 sampling sites using a Bongo net. Two well-defined periods were observed: a pre-ENSO period (December 1995-march 1997) and an ENSO event (July 1997-September 1998) characterized by impoverishment of the pelagic habitat. The highest biomass concentrations occurred at coastal stations during the pre-ENSO period. During the El Niño period no spatial patterns were found in coastal waters. The months with highest biomass were those in which the lowest sea surface temperature (SST) occurred (January-May), and this pattern was also observed during the ENSO period. A typical, although attenuated, seasonal environmental pattern with enhanced phytoplankton (diatoms and dinoflagellates) was prevalent during the El Niño event in nearshore waters. During the El Niño period the phytoplankton was mainly small diatoms (microphytoplankton), while dinoflagellates were practically absent. The most parsimonious generalized linear models explaining spatial and temporal distribution of larval fish species included the ENSO index (MEI), upwelling index (UI) and distance to the coast. The environmental variability defined on an interannual time-scale by the ENSO event and the seasonal hydroclimatic pattern defined by the UI (intra-annual-scale) controlled the ecosystem productivity patterns. The small-scale distribution patterns (defined by a cross-shore gradient) of plankton were related to the hydroclimatic seasonality and modulated by interannual anomalies.     

Hydrogeochemical and Flow Modeling of Aquitard Percolation in the Cariri Valley-Northeast Brazil

Flow modeling and hydrogeochemical inversion calculations were performed on the aquifer systems of the Crato-Juazeiro Graben in the Araripe Sedimentary Basin of the Cariri Valley, Northeast Brazil, in order to assess aquifer interconnections through an aquitard of the Araripe Plateau. Steady state hydraulic head numeric calculations with the finite difference method used Modflow software with hydrologically based boundary conditions and a piezometric surface as initial condition. Hydrogeochemical inversion with PHREEQC was performed for two water samples representing typical initial and final waters along the flow path. Flow simulation shows that approximately 20% of all recharge water from the superior aquifer system passes through the Santana aquitard reaching the middle aquifer system. Quantification of mineral dissolution/precipitation processes, ion exchange and microbiological redox reactions taking place in the aquifer systems also indicates hydraulic interconnection of the superior and middle aquifer systems through the Santana aquitard.