Summer larval fish assemblages in the Southern Tyrrhenian Sea (Western Mediterranean Sea)

The purpose of this paper was to study the community structure, in terms of species composition, abundance and spatial distribution, of fish larvae in a wide coastal area of Sicily facing the Southeastern Tyrrhenian Sea, extending for 2300 km² from Cape Cefalù to the west, to Cape Rasocolmo in the east. This study analyses how species are assembled in relation to an inshore–offshore gradient and also how environmental conditions, determined by surface circulation patterns occurring in the Central Mediterranean at the local scale, determine the distribution patterns. Samples from 39 stations were collected using a 60‐cm Bongo net during an ichthyoplanktonic survey carried out in June 2006. In all, 62 taxa, representing 32 families, were identified. Cyclothone braueri (59.6%), Engraulis encrasicolus (9.2%) Lampanyctus crocodilus (4.3%) and Lampanyctus pusillus (4.1%) were the most abundant species. The results showed that the highest abundance value (14830.6 fish larvae per 10 m² sea surface) was observed in the western part of the study area. MDS, SIMPER and CCA analyses revealed well defined groups of stations and assemblages of larvae in accordance with an inshore–offshore gradient. The results of this study could have implications for the management of marine resources because the investigated area has already been identified as a nursery area for many pelagic and coastal fishes and a natural habitat for many species of high commercial interest.     

Growth and population dynamics of the non‐indigenous species Branchiomma luctuosum Grube (Annelida,Sabellidae) in the Ionian Sea (Mediterranean Sea)

The population dynamics and gametogenesis of the non‐indigenous polychaete species Branchiomma luctuosum Grube, 1869 (Annelida, Sabellidae) has been investigated at three sites in the Taranto Seas (Ionian Sea, Mediterranean Sea). The species, probably introduced from the Red Sea, has been reported in the Mediterranean Sea since 1983. The species is hermaphrodite, and the reproductive season is between June and October when the largest mean size of oocytes was recorded together with the presence of mature spermatozoa. Small oocytes are present in specimens reaching about 20–25 mm in length. Therefore oogenesis seems to begin early during the first year of life, but the first reproduction can occur when the worms attain a larger size and are at least 6 months of age. Although most of the individuals reproduce seasonally within a discrete period, some individuals can reproduce in different periods during the year, the oogenesis of individuals not being synchronous. A life span of at least 2 years is highlighted, with a faster growth rate during the first months (about 20 mm per month) decreasing to about 10 mm from the 3rd to the 8th months and slowing down again after the worm reaches 100 mm in size. Some differences in growth performance are discussed, enhanced by comparing the sites located at greater depth (5–7 m) and those located at 0.5 m depth, together with the possible interactions of this alien species with the autochthonous sabellid Sabella spallanzanii.     

Water-soluble organic and nitrogen levels in cloud and rainwater in a background marine environment under influence of different air masses

Chemical characterization was performed on cloud and rainwater samples collected as part of the Rain In Cumulus over the Ocean Experiment (RICO). This experiment took place at a mountaintop site (East Peak) in Puerto Rico from December 2004 to March 2007 in order to determine water-soluble organic and nitrogen fractions in a marine background environment. For cloud water, similar average concentrations of 1.0 (±0.3) mg/L were found for total organic carbon (TOC) and total nitrogen (TN) and an average concentration of 0.8 (±0.2) mg/L was found for dissolved organic carbon (DOC). In rainwater, these concentrations were lower, ranging from 0.3 to 0.5 (±0.1) mg/L. Changes in the concentrations of these species were observed in periods under the influence of anthropogenic, African dust, and volcanic ash air masses. In these periods the concentrations of TOC, DOC, and TN were 2 to 4 times higher than in periods under the influence of trade winds. The insoluble organic material arriving during African dust events showed total carbon (TC) concentrations on averaging 1.5 mg/L for cloud water. The TC was composed mainly of organic carbon with polar compounds from low to high molecular weight (MW). The polar compounds with high MW were probably associated with pollution (e.g., fossil fuel combustion) from other regions. Crustal species (Al and Fe) dominated particles associated with dust episodes, confirming the soil origin. Our results suggested that a fraction (40–80%) of TOC and (<100%) of TN in Puerto Rican cloud/rainwater could be originated from long-range transport of dust, ash and/or pollution.     

Coastal Phytoplankton Do Not Rest in Winter

The climatology and interannual variability of winter phytoplankton was analyzed at the Long Term Ecological Research Station MareChiara (LTER-MC, Gulf of Naples, Mediterranean Sea) using data collected from 1985 to 2006. Background winter chlorophyll values (0.2–0.5 μg chl a dm⁻³) were associated with the dominance of flagellates, dinoflagellates, and coccolithophores. Winter biomass increases (<5.47 μg chl a dm⁻³) were often recorded until 2000, generally in association with low-salinity surface waters (37.3–37.9). These blooms were most often caused by colonial diatoms such as Chaetoceros spp., Thalassiosira spp., and Leptocylindrus danicus. In recent years, we observed more modest and sporadic winter biomass increases, mainly caused by small flagellates and small non-colonial diatoms. The resulting negative chl a trend over the time series was associated with positive surface salinity and negative nutrient trends. Physical and meteorological conditions apparently exert a strict control on winter blooms, hence significant changes in winter productivity can be foreseen under different climatic scenarios.     

An atmosphere–ocean regional climate model for the Mediterranean area: assessment of a present climate simulation

We present an atmosphere–ocean regional climate model for the Mediterranean basin, called the PROTHEUS system, composed by the regional climate model RegCM3 as the atmospheric component and by a regional configuration of the MITgcm model as the oceanic component. The model is applied to an area encompassing the Mediterranean Sea and compared to a stand-alone version of its atmospheric component. An assessment of the model performances is done by using available observational datasets. Despite a persistent bias, the PROTHEUS system is able to capture the inter-annual variability of seasonal sea surface temperature (SST) and also the fine scale spatio-temporal evolution of observed SST anomalies, with spatial correlation as high as 0.7 during summer. The close inspection of a 10-day strong wind event during the summer of 2000 proves the capability of the PROTHEUS system to correctly describe the daily evolution of SST under strong air–sea interaction conditions. As a consequence of the model’s skill in reproducing observed SST and wind fields, we expect a reliable estimation of air–sea fluxes. The model skill in reproducing climatological land surface fields is in line with that of state of the art regional climate models.     

Daily Milan Temperature and Pressure Series (1763–1998): Completing and Homogenising the Data

Daily meteorological observations have been made at the Brera astronomical observatory in Milan since 1763. Even if the data have always been collected at this observatory, the Milan series are far from being homogeneous as several changes were made to instruments, station location and observation methods. Within this context, the purpose of the paper is to discuss data homogenisation. Homogenisation is based both on objective information extracted from the station history (direct methodology) and on some statistical estimates (indirect methodology). Homogenisation by indirect methodology is mainly performed by comparison with other series whereas, if no other homogeneous series are available, it is based on the hypothesis that some statistics, such as the daily temperature range or the day to day variability, have no significant trends within some selected periods. Besides homogenisation also the completion of the series is discussed. Theresulting series are complete and homogenised daily minimum, mean and maximum temperatures and complete and homogenised daily mean pressures. They all cover the period 1763–1998.     

Late pleistocene and holocene loess deposits of the Southeastern Buenos Aires province,Argentina

The Late Pleistocene and Holocene loess deposits of the SE Buenos Aires province are composed of four allostratigraphic units that represent four episodes of loess deposition. The first and the second episodes occurred in Late Pleistocene times. The second episode was followed by a soil forming interval (Early Holocene to Mid-Holocene times). The third episode took place at about 5000 yr BP, after the Holocene sea-level maximum when marine regression began. The fourth episode constitutes a historical event of only local significance.Loess shows a fairly constant granulometric and mineralogical composition. The modal fraction consists of very fine sand and coarse silt (3 to 5 phi). They are classified as sandy silts or silty sands. Three grain-size subpopulations are differentiated: coarse, medium and fine. The medium-size subpopulation, which is the most important, consists of most of the very fine sand and coarse silt. It is thought to be transported by modified saltation and short-term suspension during local dust-storms.The mineralogical composition of loess consists of a volcaniclastic assemblage derived mainly from reworked pyroclastic deposits, primary tephras and volcaniclastic sediments. The source area of these materials was located in the lower Colorado river valley about 400 km SW of the studied area. There was also a direct supply by volcanic ash falls.