Composition and ecology of the Quercus coccifera L. communities along the eastern Adriatic coast (NE Mediterranean)

The aim of this study is to classify and describe all plant communities with Quercus coccifera covering the entire eastern Adriatic coast and islands from north Croatia to south Albania, and to relate their species composition, chorotypes and life forms to environmental factors using Pignatti ecological indicator values. From total 70 phytosociological relevés, we identified and described four floristically and ecologically distinctive vegetation communities (two new proposed subassociations, one association and stand each) using TWINSPAN and the Braun-Blanquet classification scheme. In Croatia and Montenegro, Q. coccifera is forming macchia within the Fraxino orni–Quercetum cocciferae pistacietosum lentisci. Quercus coccifera occurs only sparsely in south Croatia as a shrubland within Fraxino orni–Quercetum cocciferae nerietosum oleandri subassociation or macchia within the Erico arboreae–Arbutetum unedonis association. Despite the difference in biogeographic position and bioclimates, low shrubby Albanian Q. coccifera stands are more closely related to the Q. coccifera communities from the western Mediterranean. Eastern Adriatic communities appear exclusively within the Querceta ilicis vegetation zone and spread within the meso-Mediterranean belt. They nevertheless are an important part of the region's natural heritage and management plans must ensure that all forms of land are used in a sustainable way.     

Reproduction of Pelagia noctiluca in the central and northern Adriatic Sea

The sequence of vitellogenesis as related to size increase of the oocytes of Pelagia noctiluca (Forskål) (Scyphozoa, Semaeostomeae) was examined to assess the influence of climatic factors on its reproductive period in the central and northern Adriatic Sea. From 1981 to 1985, 5 specimens with similar diameter were sampled each month. One ovary was excised from each individual and examined both with a videoanalyzer, to count the oocytes and to check their size distribution, and through histology to assess the stage of maturation in relation to the diameter. Oocytes of all stages were present in the ovaries of individuals down to a bell diameter of 3.5 cm. Thus reproduction occurs throughout the year in the central and north Adriatic Sea. However, the number of oocytes in different developmental stages in a gonad may range from a minimum value recorded in summer to two peaks in spring and autumn. The quantitative distribution is related to sea temperature and thus to metabolic rate, and to food availability.     

Hidden secrets of the Northern Adriatic: “Tegnúe”, peculiar reefs

Research carried out over the last 40 years has underlined the scientific importance of the rocky outcrops scattered on the Northern Adriatic Sea bed sometimes referred to as “tegnúe”. The zoobenthic biocenoses developing over these peculiar geological formations are as extraordinary as they are unique. A study carried out for an entire year in two sampling stations, at different distances from the coast, revealed a very high number of zoobenthic species, including those which have now become rare and are therefore protected in Italian seas. The water turbidity of the northern Adriatic Sea greatly reduces the quantity of light reaching these outcrops, limiting the activity of autotrophic organisms only to sciaphilous genera. Thus, the most represented trophic categories of zoobenthos are suspension, especially filter feeders. Biodiversity values calculated for the communities of these particular reefs are far higher than normally found in the soft seabed in nearby areas, but even higher than in other coralligenous outcrops in other marine ecosystem in the world. The ecological role played by the tegnúe in the Northern Adriatic is extraordinary because as well as being true oases of biodiversity, they are areas naturally protected against bottom trawl-fishing. Thus, they offer shelter and reproduction sites for a number of fish and invertebrate species, including some under stress due to severe fishing pressure.     

Zooplankton community and hydrographical properties of the Neretva Channel (eastern Adriatic Sea)

Temporal and spatial variability of micro and mesozooplankton was studied in 1998 and 1999 at four stations in the Neretva Channel area influenced by the Neretva river and the open waters of the south Adriatic Sea. The area is orthophosphate limited, but an excessive accumulation of land derived nitrogen is prevented by phytoplankton uptake and the general circulation pattern. Microzooplankton was dominated by ciliates, with average abundances comparable to other Adriatic channel areas (122–543 ind. l⁻¹). Non-loricate ciliates (NLC) generally peaked in the warmer periods, but a winter increase was evident towards the inner part of the channel. Tintinnid abundances generally increased in autumn. A significant relationship with temperature was not recorded for either protozoan group. An inverse relationship between NLC and salinity might be indirectly caused by their preference for the food abundant surface layer. Mesozooplankton was dominated by copepods, with distinct summer maxima throughout the area and pronounced winter maxima of >10,000 ind. m⁻³ at the inner stations. The community was predominantly neritic but the open sea waters were important in structuring the mesozooplankton assemblage at all stations during the autumn–winter period. Although temperature regulated the seasonal dynamics of most metazoans and the species succession in the copepod community, small omnivorous copepods (Oncaea media complex, Oithona nana and Euterpina acutifrons) dominated regardless of the season. A trophic link between copepods and ciliates was evident in winter during low phytoplankton biomass.     

The Colonisation of Human-made Structures by the Invasive Alga Codium fragile ssp. tomentosoides in the North Adriatic Sea (NE Mediterranean)

Human-made structures, such as groynes, breakwaters, seawalls, pier pilings and floating pontoons, are becoming common features of the landscape in urbanised coastal and estuarine areas. Despite this tendency few studies have focused on their ecology or on their potential impacts on natural assemblages of organisms. When artificial structures are introduced in areas with little or no hard substrata, they not only provide novel habitats, which enables the colonisation of sandy areas by hard-bottom dwelling species, but they can also provide suitable habitats for exotic species. Along the north-east coast of Italy, sandy shores are protected from erosion by a line of breakwaters, which runs almost uninterrupted for about 300 km. These structures provide habitat for a variety of macroalgae and invertebrates and also for the invasive green alga Codium fragile ssp. tomentosoides. The aim of this study was, therefore, to investigate patterns of distribution of this alga on breakwaters in Cesenatico. In particular, we compared the density of thalli, biomass, length and degree of branching of C. fragile ssp. tomentosoides between the landward and the seaward sides of breakwaters, to test the hypothesis that sheltered habitats (landward) represent more suitable habitats than exposed habitats (seaward). In general, the landward side of breakwaters supported greater numbers of thalli of C. fragile ssp. tomentosoides than seaward sides. Thalli grew longer and more branched in sheltered habitats, leading to an overall larger biomass of the alga on the landward side of breakwaters. The presence of sheltered human-made hard substrata in the vicinity of major trading ports and sources of eutrophication could enhance the dispersal of invasive species across regional and geographic scales. Thus, the effects of artificial structures and introduced species on coastal assemblages cannot be evaluated separately, but their synergistic nature should be considered in planning strategies for conservation of biodiversity in coastal habitats.     

Microzooplankton in the open waters of the northern Adriatic Sea from 1990 to 1993: the importance of copepod nauplii densities

Zooplankton was sampled during 39 cruises, from 1990 to 1993, at four fixed stations in the open northern Adriatic. Hydrographic factors were important in determining the abundance of the smallest and largest components of the northern Adriatic food chain during this period. Nauplii—especially those of the smallest size fractions—were the major mediators of material transfer between primary producers and higher trophic levels. There was a significant difference in the vertical distribution of nauplii size fractions between the eastern and western parts of the northern Adriatic, but not in their population density. According to multiple correlation analyses, the abundance of naupliar size fractions in the western area correlated strongly with temperature and with certain biological factors. This study confirms the important influence of the Po River and of mid-Adriatic waters on the planktonic ecosystem of the northern Adriatic. Electronic Publication     

IDENTIFICATION OF ALEXANDRIUM (DINOPHYCEAE) SPECIES USING PCR AND rDNA-TARGETED PROBES

A PCR (polymerase chain reaction)-based assay for the detection of Alexandrium species in cultured samples using rDNA-targeted probes was developed. The internal transcribed spacers 1 and 2 (ITS1 and ITS2) and the 5.8S ribosomal RNA gene (rDNA) from cultured isolates of A. tamarense (Lebour) Taylor, A. catenella (Whedon et Kofoid) Balech, A. fundyense Balech and A. lusitanicum Balech were amplified using PCR and sequenced. Sequence comparisons showed that the 5.8S and ITS1-ITS2 regions contain sequences specific for the Alexandrium genus, especially at the 3' end of the 5.8S coding region. PCR primers and a radioactive ³²P-labeled DNA probe were devised for this region. The cross-reactivity of the PCR primers and probe was tested against cultured isolates of Alexandrium and other dinoflagellates and diatoms. All the Alexandrium isolates screened reacted toward the genus-specific probe; in contrast, the other groups of microalgae (dinoflagellates and diatoms) did not react with the probe. Furthermore, the PCR amplification technique combined with the use of the rDNA-target probe allowed us to develop a method for the detection of Alexandrium cells in cultured samples. This PCR method might offer a new approach for the identification and enumeration of the HAB (harmful algal bloom) species present in natural phytoplankton populations.     

Cage culture effects on mullets (Mugilidae) liver histology and blood chemistry profile

A comparative study of blood chemistry and histology was conducted on two groups of mullets (Mugilidae) living under different conditions with different feed sources. The aquaculture influenced mullet group (AIM), was collected near fish farms and the control group of mullet (CM) was caught in the waters without any aquaculture activities. Histological and biochemical procedures were employed to study liver histomorphology, plasma aspartate and alanine aminotransferase (AST, ALT), triglyceride (TRIG), cholesterol (CHOL), glucose (GLU) and total protein (TP) of both AIM and CM. Moderate histological changes (lipid infiltration) were observed in the liver of AIM. Significant changes in plasma variables were observed in AIM. Blood chemistry variables measured proved to be good indicators of artificial feed effects. Classical statistical approaches were applied to the blood chemistry and histopathology data. For the first time machine learning techniques were used to generate comprehensible classification models and to explore blood chemistry variable importance, strength, their mutual interactions or dependencies, and to investigate reliability of particular variables within the groups.     

FUnaria mediterranea monstruositäten aus italien

Abstract

The aim of the present study is to demonstrate the value of some nitrophilous plants as bioindicators related to global warming. As a case study, the space–time dynamics of the populations of some nitrophilous and ruderal species have been investigated along the southern-central Adriatic side of the Italian Peninsula. These have been examined according to the range of their distribution areas, to their ecological needs, and to the availability of past data, which have then been related to the data on global warming across the same territories. The choice for this investigation was for nitrophilous species with a Mediterranean distribution – of the Stenomediterranean type – and for some recent entries into the local flora as alien species. The spread of these species occurs in areas with intense human activity, where they have exploited the conditions of the warmer niche, such that their presence and their spatial spread observed over time are clearly linked to global warming. For all of the species in question, rapid increases in the population numbers have been observed, along with a northward shift of their distribution areas. These changes correspond to the increase in average annual temperature as revealed by the thermometric measurements.