Variable hydrology and salinity of salt ponds in the British Virgin Islands

Caribbean salt ponds are unique wetlands that have received little scientific attention. They are common features of dry Caribbean coastlines, but they are threatened by rapid coastal development. We compared hydrology and salinity of 17 salt ponds in the British Virgin Islands. Ponds were mostly hypersaline (>50 ppt), and they exhibited dramatic salinity fluctuations in response to rainfall and evaporation. Individual ponds varied in their mean salinities and thus experienced different ranges of salinity. Differences in mean salinity appeared to be linked with hydrological characteristics. Hydrological variation ranged from permanently inundated ponds with direct sea connection to those fully isolated from the sea and retaining water only after rainfall. We characterized groups of ponds by their major hydrological characteristics, particularly their period of inundation and their degree of connection with the sea. The resulting classification appeared to reflect a continuum of increasing isolation from the sea, concurring with published geological records from salt pond sediments elsewhere. The patterns of variability and succession described here are applicable to salt pond management interests throughout the Caribbean

Pautas de distribución espacial y modelización mediante SIG del habitat de Larvas de Solea solea, Pleuronectes flesus y limanda en la parte oriental del Canal de la Mancha durante la primavera

The spring distribution of larval fish stages of flatfishes in the Dover Strait (eastern English Channel) was studied in 1995 and 1999. Fish larvae were identified and sorted according to developmental stages in order to study their ontogenic distribution. The French coastal waters are characterised by an unstable tide-dependent front, which influences larval dispersion. In spring, the French coastal waters have a high phytoplanktonic production. They have higher temperatures, lower salinities and differences in current intensity compared with the central English Channel waters. Generalised Additive Models (GAM) combined with Geographic Information Systems (GIS) were used to model the potential habitats of life stages considering data from three major surveys in this area. The models were developed by coupling presence-absence models with non-null abundance models. The potential habitat of larval stages was then mapped using a geostatistical method (kriging). This revealed different species strategies in which young stages were abundant in central waters and older ones were distributed mainly along the French and Belgian coasts. It is concluded that the central English waters are important for young stages after hatching and that coastal waters are essential nurseries for future juveniles. The models of three flatfish species having similar life cycle strategies are presented here: Limanda limanda, Platichthys flesus and Solea solea.Durante 1995 y 1999 se estudió la distribución primaveral de los estadios larvarios de peces planos en el Estrecho de Dover (parte oriental del Canal de la Mancha).Las larvas de peces fueron identificadas y separadas en función de su estadio de desarrollo con objeto de estudiar su distribución ontogénica. Las aguas costeras francesas se caracterizan por un frente de marea inestable, que influencia la dispersión larvaria. Durante la primavera, dichas aguas presentan una elevada producción fitoplanctónica. Asimismo, presentan altas temperaturas, bajas salinidades y diferencias en la intensidad de la corriente, comparado con las aguas centrales del Canal de la Mancha. A partir de datos obtenidos en tres amplias campañas en este área, se utilizaron Modelos Aditivos Generalizados (GAM) con Sistemas de Información Geográfica (SIG) para modelizar los hábitats potenciales de los estadios larvarios. Los modelos se desarrollaron uniendo modelos de “presencia-ausencia” con modelos de “abundancia no nula”. A continuación, usando métodos geoestadísticos (kriging) se representó el mapa del hábitat potencial de los estadios larvarios. Esto reveló diferencias en las estrategias de aquellas especies cuyos primeros estadios son abundantes en las aguas centrales y cuyos estadios más avanzados están distribuidos principalmente a lo largo de la costa francesa y belga. Se mostró la importancia de las aguas centrales del Canal de la Mancha para las larvas lecitotróficas, y como las aguas costeras son áreas de cría esenciales para los futuros juveniles. Aquí se presentan los modelos para tres especies de peces planos que tienen estrategias de vida similares: Limanda limanda, Platichthys flesus and Solea solea

MODELAMIENTO DE LAS CONSECUENCIAS PREVISIBLES DEL DRAGADO DE LOS PRINCIPALES RÍOS AMAZÓNICOS SOBRE LA FAUNA SILVESTRE Y LA GENTE DE LOS BOSQUES INUNDADOS DE LORETO, PERÚ

Dredging activities are planned for the Amazon hydrovia project and there is limited scientific evidence of how the proposed dredging could affect both biodiversity and the local population. A model matrix was used to evaluate the possible consequences of dredging on wildlife. According to the matrix, aquatic species show decreasing populations when the water level is low and terrestrial species are negatively affected when floods are intensive. The indigenous Cocama population has adapted to the population changes of the wildlife, dedicating itself more to fishing when the populations of game animals decrease. Shallow areas, locally called "malos pasos", are important habitat types for fish and dolphins. According to the matrix presented in this study, the best scenario would be that the dredging activities do not affect the normal water levels; while, the worst scenario would be when there are droughts and intensive floods.Se planean actividades de dragado por el proyecto hidrovía amazónica y existe limitada evidencia científica de cómo el dragado propuesto podría afectar tanto a la biodiversidad como a la población local. Una matriz modelo fue utilizada para evaluar las posibles consecuencias del dragado sobre la fauna silvestre. De acuerdo con la matriz, las especies acuáticas muestran poblaciones decrecientes cuando el nivel de agua está bajo y las especies terrestres se ven afectadas negativamente cuando las inundaciones son intensivas. La población indígena Cocama viene adaptándose a los cambios poblacionales de la fauna silvestre, dedicándose más a la pesca cuando las poblaciones de animales de caza disminuyen. Las áreas poco profundas, localmente denominados como “malos pasos” constituyen tipos de hábitat importantes para peces y delfines. De acuerdo a la matriz que se presenta en este estudio, el mejor escenario sería que, las actividades del dragado no afecten los niveles de agua normales; mientras que, el peor escenario sería cuando se presenten sequías e inundaciones intensivas

Major shifts in Amazon wildlife populations from recent intensification of floods and drought

In the western Amazon Basin, recent intensification of river‐level cycles has increased flooding during the wet seasons and decreased precipitation during the dry season. Greater than normal floods occurred in 2009 and in all years from 2011 to 2015 during high‐water seasons, and a drought occurred during the 2010 low‐water season. During these years, we surveyed populations of terrestrial, arboreal, and aquatic wildlife in a seasonally flooded Amazonian forest in the Loreto region of Peru (99,780 km2) to study the effects of intensification of natural climatic fluctuations on wildlife populations and in turn effects on resource use by local people. Shifts in fish and terrestrial mammal populations occurred during consecutive years of high floods and the drought of 2010. As floods intensified, terrestrial mammal populations decreased by 95%. Fish, waterfowl, and otter (Pteronura brasiliensis) abundances increased during years of intensive floods, whereas river dolphin and caiman populations had stable abundances. Arboreal species, including, macaws, game birds, primates, felids, and other arboreal mammals had stable populations and were not affected directly by high floods. The drought of 2010 had the opposite effect: fish, waterfowl, and dolphin populations decreased, and populations of terrestrial and arboreal species remained stable. Ungulates and large rodents are important sources of food and income for local people, and large declines in these animals has shifted resource use of people living in the flooded forests away from hunting to a greater reliance on fish