On robust estimation of the location parameter

Trabajo presentado en el 39th CIESM Congress, celebrado en Venecia, Italia, del 10 al 14 de mayo de 2010

/pdf/biodiversity-of-the-mediterranean-sea-estimates-patterns-and-2mjs6mi5cx.pdf

Biodiversity of the Mediterranean Sea: estimates, patterns and threats

The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well.

This abstract has been translated to other languages (File S1).

/pdf/the-biodiversity-of-the-mediterranean-sea-estimates-patterns-38y4s7jond.pdf

The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats

Global climate change is impacting and will continue to impact marine and estuarine fish and fisheries. Data trends show global climate change effects ranging from increased oxygen consumption rates in fishes, to changes in foraging and migrational patterns in polar seas, to fish community changes in bleached tropical coral reefs. Projections of future conditions portend further impacts on the distribution and abundance of fishes associated with relatively small temperature changes. Changing fish distributions and abundances will undoubtedly affect communities of humans who harvest these stocks. Coastal-based harvesters (subsistence, commercial, recreational) may be impacted (negatively or positively) by changes in fish stocks due to climate change. Furthermore, marine protected area boundaries, low-lying island countries dependent on coastal economies, and disease incidence (in aquatic organisms and humans) are also affected by a relatively small increase in temperature and sea level. Our interpretations of evidence include many uncertainties about the future of affected fish species and their harvesters. Therefore, there is a need to research the physiology and ecology of marine and estuarine fishes, particularly in the tropics where comparatively little research has been conducted. As a broader and deeper information base accumulates, researchers will be able to make more accurate predictions and forge relevant solutions.

/pdf/effects-of-global-climate-change-on-marine-and-estuarine-2a0jtq3rze.pdf

Effects of global climate change on marine and estuarine fishes and fisheries

Seasonal precipitation variability in the east of the Iberian Peninsula is weakly linked to the North Atlantic Oscillation (NAO) during autumn and winter. For the purpose of improving the study of its performance, low-frequency variability patterns specific to the Mediterranean basin have been searched for. In this way, the Western Mediterranean Oscillation (WeMO) has been defined by means of the dipole composed, in its positive phase, by the anticyclone over the Azores and the depression over Liguria, and its index (WeMOi), as a result of the difference of the standardised values in surface atmospheric pressure in San Fernando (Spain) and Padua (Italy). This new index allows the detection of the variability relevant to the cyclogenesis next to the western Mediterranean basin, which determines in a predominant way the types of rainfall in the Gulf of Valencia. In this area, the WeMO is significantly better than the NAO to explain the monthly pluviometric anomalies during these seasons. Also, a daily resolution of the WeMOi can provide a useful tool to forecast torrential rainfall events in the north-western zones of the Mediterranean (eastern part of the Iberian Peninsula and the south of France), and such significantly daily rainfall frequencies for different thresholds. Copyright © 2006 Royal Meteorological Society.

The western mediterranean oscillation and rainfall in the iberian peninsula

In order to establish the connection between the hydroclimate variables and pelagic species, year-to-year fluctuations of small pelagic fish landings in the eastern Adriatic coast were compared to climatic fluctuations over the Northern Hemisphere and to salinity fluctuations in the Adriatic. Using this approach, basic climatic oscillations were determined for both hydroclimate and biological data. The main climate oscillation period was approximately 80 yr and an interrelation between climatic fluctuations over the Northern Hemisphere and small pelagic fish landing data was found. The results suggest a linkage between the advection of Levantine Intermediate Water, which is controlled by the pressure distribution over the wider area, and fish abundance in the Adriatic Sea.

/pdf/long-term-changes-in-landings-of-small-pelagic-fish-in-the-4zxvpi1q48.pdf

Long-term changes in landings of small pelagic fish in the eastern Adriatic — possible influence of climate oscillations over the Northern Hemisphere

The response of phytoplankton community to anthropogenic pressure gradient in the coastal waters of the eastern Adriatic Sea

Interannual variability of the primary production in the middle Adriatic Sea for the period 1961-2002 was examined and correlated to the various atmospheric and oceanographic parameters. The Locally-weighted scatter plot smoothing (LOWESS) method (Cleveland, 1979) and Sequential algorithm for regime shift detection (SARS, Rodinov, 2004) were applied to the primary production mean annual and spring-summer values, revealing the three periods with significantly different mean productivity rate: 1961-1979, 1980-1996 and 1997-2002. Moreover, the period from 1980 to 1996, with the highest primary production, consists of the two distinguished regimes: periods of increasing (1980-1986) and decreasing (1987-1996) primary production. Whereas in the first period the ecosystem was under the influence of warmer and nutrient richer Levantine Intermediate Water (LIW) intrusions into the Adriatic, in the second period, which started with cold winter 1987, the Eastern Mediterranean Transient (EMT) occurred in the Mediterranean. The new circulation regime prevented the LIW intrusions in the Adriatic, causing its reduced productivity. Weak ventilation in the Adriatic was evidenced in the lower than normal sea temperature and oxygen concentrations bellow the thermocline depth. Analysed atmospheric data: air temperature, precipitation, evaporation, air-sea fluxes and the North Atlantic Oscillation (NAO) index showed similar fluctuation pattern as oceanographic data. Changed regime in the ecosystem, observed around 1980s till the end of 1996 can be also associated to the lower than normal precipitation rate, which is connected with more clear days and higher solar radiation input in the sea. Our analysis connected the shifts in primary production with changes in the climate system via changes in the atmosphere and confirmed the hypothesis that atmospheric variability can trigger the ecosystem changes.

/pdf/the-relationship-between-the-atmospheric-variability-and-3femb7wjir.pdf

The relationship between the atmospheric variability and productivity in the Adriatic Sea area

Unusual weather conditions over the southern Europe and the Mediterranean area in 2003 significantly impacted the oceanographic properties of the Adriatic Sea. To document these changes, both in the atmosphere and the sea, anomalies from the normal climate were calculated. The winter 2003 was extremely cold, whereas the spring/summer period was extremely warm. The air temperature in June was more than 3 standard deviations above the average. On the other hand, precipitation and river runoff were extremely low between February and August. The response of the sea was remarkable, especially in surface salinity during spring and summer, with values at least one standard deviation above the average. Analysis of thermohaline properties in the middle Adriatic showed the importance of two phenomena responsible for the occurrence of exceptionally high salinity: (1) enhanced inflow of saline Levantine Intermediate Water (LIW) in the Adriatic, and (2) extremely low precipitation and river runoff, accompanied with strong evaporation. Two large-scale atmospheric indices: NAOI (North Atlantic Oscillation Index) and MOI (Mediterranean Oscillation Index), although generally correlated to the Adriatic climate, failed to describe anomalies in 2003. The air pressure gradients used for the definition of both indices significantly decreased in 2003 due to the presence of the high pressure areas over most of Europe and the northern Atlantic, and were actually responsible for the observed anomalies above and in the Adriatic.

/pdf/response-of-the-adriatic-sea-to-the-atmospheric-anomaly-in-36dff8bbky.pdf

Response of the Adriatic Sea to the atmospheric anomaly in 2003

Salinity and temperature time series were analysed for the open sea stations at the transect Split-Gargano, in the middle Adriatic, for the period 1961-1980. Thermohaline fluctuations were described in terms of the principal
component scores and, in addition, were compared to heat and water flux at the atmosphere-sea interface. Temperature and salinity vertical gradients in the surface layer are well related to surface fluxes during the whole year. In deeper layers this influence is visible only under the vertically homogenous conditions. Vertical fluxes of heat and salt, compared to the rate of change of the heat and salt content, point to the season with important advection effects. Vertical exchange prevails in the cold season, while horizontal exchange is considerable in the warm period.

Mira Morović

Papers

Long-term changes in landings of small pelagic fish in the eastern Adriatic — possible influence of climate oscillations over the Northern Hemisphere

The response of phytoplankton community to anthropogenic pressure gradient in the coastal waters of the eastern Adriatic Sea

The relationship between the atmospheric variability and productivity in the Adriatic Sea area

Response of the Adriatic Sea to the atmospheric anomaly in 2003

Seasonal thermohaline fluctuations in the middle Adriatic Sea