The effects of northern italian rivers and Eastern Mediterranean ingressions on the phytoplankton of the Adriatic Sea

An analysis of the distribution of the phytoplankton standing crop during a period of high stability characterized the relative influence of northern Italian rivers and Mediterranean waters on the Adriatic Sea. The region influenced by northern Italian rivers was marked by low community diversities, relatively high chlorophyll a standing crops and cell densities, high microplankton to nannoplankton community volume ratios, and the dominance of Nitzschia seriata. To the contrary, the region influenced by Mediterranean waters exhibited high community diversities with prominent oceanic and warm water elements, low chlorophyll a standing crops and microplankton cell densities, low microplankton to nannoplankton ratios, and a relatively conspicuous coccolithophore flora.Nannoplankton populations remained relatively constant throughout the Adriatic. However eutrophication resulted in a marked increase in the microplankton component of the community, with the diatom Nitzschia seriata serving as a prime indicator of the process, even in regions several hundred kilometers downstream from nutrient sources.Even under relatively low rates of river discharge, the influence of northern Italian rivers could be traced along the entire western sode of the sea to the Otranto Strait, with low north to south and high west to east gradients resulting from the effect of a cyclonic surface circulation pattern on inflowing Mediterranean waters in the south and river discharge in the north.     

Temporal variability in abundance and biomass of ciliates and copepods in the eutrophicated part of Kaštela Bay (Middle Adriatic Sea)

Seasonal variations in abundance and carbon biomass of ciliated protozoa and micrometazoa were studied from May 1998 to November 1999 in the eutrophicated area of Katela Bay (Middle Adriatic Sea). Ciliates showed peaks in spring and autumn, primarily due to changes in the abundance and biomass of tintinnines, which participated in total ciliate abundance and biomass with 40.48 and 60.02%, respectively. The highest tintinnine density was 4,278 ind. l^–1, while their average biomass varied from 0.611 to 26.557 gC l^–1 . Maximal average density and biomass of non-loricates were 1,430 ind. l^–1 and 3.925 gC l^–1, respectively. The micrometazoa community was dominated by copepod nauplii, especially during the summer and autumn. The copepod biomass ranged between 3.47 and 26.75 gC l^–1 . High abundance and biomass values of the investigated zooplankton groups point to an important role of these organisms in the secondary production in the Bay, indicating that they may be (1) a crucial factor in controlling the populations of nano-/pico-phytoplankton and heterotrophic nanoflagellates, and (2) a significant prey for larger micrometazoans.     

Nomenclatural remarks on the chasmophytic vegetation of the Centaureo-Campanuletalia

The thermophilous chasmophytic vegetation on limestone of the Adriatic Region has been arranged in the endemic order Centaureo-Campanuletalia (class Asplenietea trichomanis). The distribution range of the order covers a large area around the Adriatic Sea – from the south and north east of Italy to Slovenia, Croatia, Bosnia i Hercegovina, Montenegro and Albania. The Centaureo-Campanuletalia or its subordinated syntaxa are quoted in the main syntaxonomic synopses of the Region as well as in technical reports. The critical analysis of the nomenclature of the order, based on the International Code of Phytosociological Nomenclature (ICPN), showed many invalid or incorrect names while it is evident that the usage of correct names in scientific literature is crucial, both for the advances of syntaxonomic knowledge and their application for practical purposes. This paper presents a revision of the nomenclature for the Centaureo-Campanuletalia and related syntaxa in order to stabilize this nomenclature at least at alliance level. As a result, three syntaxa were validated (Centaureo dalmaticae-Campanuletalia pyramidalis, Centaureo cuspidatae-Portenschlagiellion ramosissimae, Inulo verbascifoliae-Centaureetum cuspidatae) and five others were lectotypified.     

Syntaxonomy of Arundo stands along the eastern Adriatic coast

Based on the diagnostic morphological characters of the Arundo taxa, and after both field and herbarium observation, three species (A. micrantha, A. plinii and A. donax) were found along the eastern Adriatic coast. Altogether, 50 phytocoenological relevés from Arundo stands were collected in Croatia, Montenegro and Albania between 2010 and 2013. Three associations with a predominance of Arundo species were determined: Arundinetum plinianae, Arundinetum micranthae and Arundini donacis–Convolvuletum sepium. Among them, Arundinetum micranthae is described and proposed as a new association, belonging to the Artemisietea vulgaris class. It occurs frequently along the coastal belt between the cities of Split and Dubrovnik in South Croatia. The syntaxonomy of the associations is discussed and comparison with similar communities from Italy is made. The vegetation and floristic structure of the associations is discussed as a potential basis for biodiversity conservation programmes and for evaluating the state of these ecosystems in the future.     

Nuclear abnormalities of marine fish erythrocytes

The aim of this study was to monitor erythrocyte nuclear abnormalities (NA) including micronuclei (MN) in cultured and wild sea bass Dicentrarchus labrax and wild mullet Mugil spp. Seasonal sampling was performed at seven locations along the eastern coast of the Adriatic Sea. The frequency of NA and MN was positively correlated to temperature (NA: P < 0·05, r = 0·11; MN P < 0·05, r = 0·10), and there was also a positive correlation between NA and MN frequency ( P < 0·001, r = 0·43). The lowest NA and MN values for both fish species were recorded in spring, while the highest were recorded in autumn. Significantly higher frequency of NA was seen in D. labrax compared to Mugil spp., while MN frequency was low in both species and not significantly different. There was no significant difference in NA and MN frequency between cultured and wild D. labrax sampled in the same month, and there was no difference between wild Mugil spp. sampled near or far from fish farms. In view of sampling sites, the highest values were detected in fishes from the Limski Channel, the lowest from the Janjina location.     

Benthic ciliates in Adriatic Sea lagoons

Sediment samples were collected from four sandy and muddy bottom sites at both Sacca di Goro lagoon (northern Adriatic Sea) and Lesina lagoon (southern Adriatic Sea) on one occasion in May and one occasion in July in order to make a comparative study of ciliate abundance and diversity. The temperature, pH, dissolved oxygen, and redox potential were measured at the time of collection, the water content of the sediments was determined, and samples subjected to granulometric analysis. The ciliated protozoa in sub-samples from the top centimeter of sediment were identified to genus and species level and enumerated. Ciliates belonging to 38 and 33 species were found in the sediment of Sacca di Goro and Lesina, respectively, the diversity of ciliates varying widely between stations. Total ciliate numbers ranged from 32 to 759 cm(-2) and from 2 to 256 cm(-2) at Sacca di Goro and Lesina, respectively; the ciliate biomass ranged from 1.1 to 30.3 microg C cm(-2) in the samples collected at Sacca di Goro, and from 0.01 to 157 microg C cm(-2) in the samples collected at Lesina lagoon. Aspidisca lynceus, Aspidisca steini, Chilodonella uncinata, Frontonia marina, Pleuronema marinum, Strombidinopsis minimum, Strombidium sp., and Urotricha sp., were observed at the two lagoons but not in all stations; Keronopsis flavicans and Trachelostyla pediculariformis were often numerous at Goro lagoon, A. lynceus, Condylostoma patulum and Tracheloraphis teissieri were the most abundant ciliates observed at Lesina lagoon.     

Ecological and morphological characteristics of Ephelota gemmipara (Ciliophora,Suctoria), epibiontic on Eudendrium racemosum (Cnidaria,Hydrozoa) from the Adriatic Sea

The relationship between the suctorian Ephelota gemmipara and the large hydroid Eudendrium racemosum from the North Adriatic Sea has been studied over its full annual cycle. Ephelota gemmipara settles on the perisarc of the hydroid, usually close to the hydranths in order to exploit the hydroid's food discharges. The life cycle of E. gemmipara is influenced by temperature variations and by its relationship with the host. The hydroid shows an active phase in the summer, and it gets through the adverse winter season forming resting stages. In April, when temperature increases, the hydroid starts its active phase and it is colonized by suctorians. From May to September the suctorians produce multiple buds (swarmers) that detach from the parental cells to settle on an Eudendrium colony. The abundance of the suctorian peaks in September, with more than 1.2 million ind. m^?2. Their proliferation coincides with the maximal abundance of their host and the highest water temperatures. On the contrary, sexual reproduction and the encystment occur when the temperature and the abundance of E. racemosum decrease. Lastly, we also report the presence of symbionts such as bacteria and the parasitic protozoans Tachyblaston ephelotensis and Enigmocoma acinetarum.     

The genus Dinophysis in the Southern Adriatic Sea

Abstract

Some preliminary results of a survey carried out along the Southern Adriatic coasts (Brindisi-S.M. Leuca) are reported in order to contribute to the knowledge of the phytoplankon community of this area. Ten Dinophysis species had been identified, four of them are known to be involved in DSP mussel contamination. Spatio-temporal distribution of Dinophysis spp. is shown.