Picoplankton composition related to thermohaline circulation: The Albanian boundary zone (southern Adriatic) in late spring

Picoplankton distribution at the boundary zone of the southern Adriatic in May 2009 on a 75 km long shelf-continental slope transect was assessed by combining epifluorescence microscopy, flow cytometry and high-performance liquid chromatography data with hydrographic observations. The picoplankton distribution was greatly influenced by the hydrographic conditions prevailing in the southern Adriatic because of the influence of the Levantine Intermediate Water (LIW) and East Adriatic Current (EAC) forcing. Heterotrophic bacteria numerically dominated the picoplankton community through the entire transect with no significant accumulation. By contrast, picophytoplankton accumulated in the 50–75 m layer, forming a pronounced deep chlorophyll maximum. Synechococcus dominated the photosynthetic picoplankton, whereas picoeukaryotes were the least abundant. The intrusion of warm LIW observed in the layer between 100 and 350 m was followed by Prochlorococcus and Synechococcus peaks (10 × 10³ cells mL⁻¹ and 90 × 10³ cells mL⁻¹, respectively), as well as by the appearance of two Synechococcus ecotypes. Most picoeukaryotes were observed at the offshore stations, where geostrophic current calculation revealed the strongest EAC influence. A strong EAC spread over the central and eastern basin created a barrier for Prochlorococcus, whereas the picoeukaryote maxima coincided with the core of the EAC, suggesting its persistence to hydrological instabilities.     

Phytoplankton driven distribution of dissolved and particulate lipids in a semi-enclosed temperate sea (Mediterranean): Spring to summer situation

The relationship between changes in lipid classes and phytoplankton composition and abundance in the northern Adriatic was studied during spring and summer 2008 at two stations with different nutrient levels, i.e. at the western mesotrophic and eastern oligotrophic areas. Changes in the phytoplankton community depended on temporal surface nutrient depletion and bottom accumulation; that is, microphytoplankton, mainly diatoms Pseudo-nitzschia sp., developed at nutrient richer surface layers of the mesotrophic area in spring and at deeper layers of the oligotrophic site in late summer. In other periods nanophytoplankton dominated. Dissolved organic carbon (DOC) and lipid content were comparable for the two stations, while particulate organic carbon (POC) was richer at the mesotrophic side. Total lipid concentrations varied in the range from 8.0 to 92.2 μg l⁻¹ and from 16.9 to 76.9 μg l⁻¹ in the dissolved and particulate fractions, respectively. DOC and POC contents were in the ranges from 0.77 to 1.58 mg l⁻¹ and from 0.06 to 0.56 mg l⁻¹, respectively. Lipid and organic carbon distribution did not follow phytoplankton progression, indicating decoupling between organic matter production and decomposition throughout the investigation period. The main sources of lipids were marine phytoplankton and bacteria. Low nutrient conditions caused increased biosynthesis of lipids. Also, increasing oligotrophy led to an increasing number of phytoplankton taxa. The synthesis and accumulation of glycolipids by the developed taxa were enhanced during nutrient exhaustion, contributing in late summer, on average, 20.2 and 22.0% at the mesotrophic and oligotrophic stations, respectively, in the particulate fraction. The distribution of bacterial lipids and lipid breakdown products implies that bacterial lipid degradation was significant in spring, while very probably lipid abiotic degradation took place during summer.     

Effectiveness of conventional management in Mediterranean type artisanal fisheries

Artisanal fisheries throughout the Mediterranean region are managed mostly by applying gear specific regulations. The data about the extent and dynamics by which littoral fish resources respond to commonly proposed changes of such regulations are lacking. Here the results of a 15 year (1995–2009) monitoring programme of littoral fish resources in a pilot region of island Vis aquatorium, central Adriatic Sea, are reported with the scope of investigating whether a more restrictive fishing regime (encompassing an increase in minimum inner layer mesh size of trammel net from 28 to 40 mm and excluding the trammel net from subsistence artisanal fishing) that has progressively been put in place during the study period has been accompanied by expected positive changes of littoral fish resources’ abundance, biomass and structure. Significant increases over time were observed in most of the community indices analyzed (abundance and biomass catch per unit effort, diversity indices) as well as a directional change in abundance and biomass catch composition of littoral fish resources. Positive responses were, however, primarily related with a recovery of Mullus surmuletus stock. Additionally, time-series analysis of ABC curves and their corresponding W index revealed that fish community in the study area was still moderately disturbed. Limited extent of conventional management restorative potential is further exacerbated by social issues – noncompliant behavior mainly among subsistence artisanal fishers and consequent resentment of commercial artisanal fishers. In order to improve further the state of the resources a more comprehensive set of management measures incorporating closed areas and a new approach actively involving fishers in the management process should be adopted.     

Improving the recreational value of Ireland's coastal resources: A contingent behavioural application

This paper measures willingness to pay (WTP) for public access to additional beach area and trail improvements to a coastal recreational site in the west of Ireland. The Contingent Behaviour model is used to measure the increased number of trips associated with improved public access using a connecting trail between two beach areas along a stretch of Irish coastline. Results show that improving access through the use of the connecting trail increases consumer surplus by €111.15 per person per annum. It is argued that in designing new regulation such as Marine Protected Areas (MPAs) for the management of Ireland's coastline, an understanding of the values the Irish public place on coastal recreational access will be important to manage the resource in a sustainable manner.     

Spectrum Disentangling and Orbital Solution for κ Dra

Based on a new set of electronic spectra in a relatively wide spectral range (3500–8300 Å) and using the methods of spectrum disentangling (code KOREL) and solution of RV curves (code FOTEL), we determined new orbital elements of the binary star κ Dra. The solution of the radial velocity curves for Balmer and some other strong metallic lines suggested a circular orbit and led to the following orbital elements: period P = 61.555 ± 0.029 days, epoch of periastron passage T _periast = 49980.22 ± 0.59, RV semi-amplitude K ₁ = 6.81 ± 0.24 km s^?1, and a mass function of f(m) = 0.002 M _⊙. Lines of the secondary were not detected. In addition, moving absorption bumps in the violet peaks of Hα and Hβ lines were found to be phase-locked with the orbital period. Their presence suggests some kind of interaction between the binary components.     

Formation and Evolution of Intermediate Mass Black Hole X-Ray Binaries

The evolution of young (≲ 10 Myr) star clusters with a density exceeding about 10⁵ star pc⁻³ are strongly affected by physical stellar collisions during their early lifetime. In such environments the same star may participate in several tens to hundreds of collisions ultimately leading to the collapse of the star to a black hole of intermediate mass. At later time, the black hole may acquire a companion star by tidal capture or by dynamical – three-body – capture. When the captured star evolves it starts to fill its Roche-lobe and transfers mass to its accompanying black hole. This then leads to a bright phase of X-ray emission, which lasts for the remaining main-sequence lifetime of the donor. If the star captured by the intermediate mass black hole is relatively low mass ≲ 2 M⊙) the binary will also be visible as a bright source in gravitational waves. Based on empirical models we argue that, for as long as the donor remains on the main sequence, the source will be ultraluminous L_x >rsim 10⁴⁰ ergs^-1 for about a week every few month. When the donor star is more massive >15 M⊙, or evolved off the main sequence the bright time is longer, but the total accretion phase lasts much shorter.     

Growth rates of Rhizocarpon geographicum lichens: a review with new data from Iceland

This paper reviews evidence from previous growth‐rate studies on lichens of the yellow‐green species of Subgenus Rhizocarpon—the family most commonly used in lichenometric dating. New data are presented from Rhizocarpon section Rhizocarpon thalli growing on a moraine in southern Iceland over a period of 4.33 yr. Measurements of 38 lichen thalli, between 2001 and 2005, show that diametral growth rate (DGR, mm yr^?1) is a function of thallus size. Growth rates increase rapidly in small thalli (<10 mm diameter), remain high (ca. 0.8 mm yr^?1) and then decrease gradually in larger thalli (>50 mm diameter). Mean DGR in southern Iceland, between 2001 and 2005, was 0.64 mm yr^?1 (SD = 0.24). The resultant growth‐rate curve is parabolic and is best described by a third‐order polynomial function. The striking similarity between these findings in Iceland and those of Armstrong ( 1983 ) in Wales implies that the shape of the growth‐rate curve may be characteristic of Rhizocarpon geographicum lichens. The difference between the absolute growth rate in southern Iceland and Wales (ca. 66% faster) is probably a function of climate and micro‐environment between the two sites. These findings have implications for previous lichenometric‐dating studies, namely, that those studies which assume constant lichen growth rates over many decades are probably unreliable. © British Geological Survey/Natural Environment Research Council copyright 2006. Reproduced with the permission of BGS/NERC. Published by John Wiley & Sons, Ltd.