Seasonal patterns in the mesopelagic fish community and associated deep scattering layers of an enclosed deep basin

Mesopelagic fish constitute the most abundant vertebrate group in the marine environment. The current work reports on results of three seasonal acoustic cruises carried out in the Gulf of Corinth, a relatively small, deep, isolated basin located in the Central Mediterranean (Greece) that presents some unique geomorphological and ecological features. The aim of this study was to describe seasonal echo-types and the vertical distribution of the Deep Scattering Layers (DSLs) as well as to relate them with specific species or species groups. Mesopelagic fish dominated the pelagic ecosystem as confirmed by biological sampling with different gears during daytime and nighttime. In total, at least 15 species were caught, belonging to the families Myctophidae, Paralepididae, Sternoptychidae and Stomiidae, while the-elsewhere very abundant-families Gonostomatidae and Phosichthyidae were completely absent. Common echo-types included: (a) shoals and schools formed by the silvery lightfish Maurolicus muelleri, usually located along the shelf break (80-225 m), (b) a non-migrant thin DSL found at 150-280 m throughout the deep parts of the Gulf, dominated by juvenile half-naked hatchetfish Argyropelecus hemigymnus, and (c) one thick, partially migratory DSL at 250-600 m, mainly consisting of myctophids. The echo backscatter characteristics and species composition of the DSLs as well as the length distribution of the populations were found to differ seasonally. Species-specific and size related patterns in the vertical distribution of fish were detected both during daytime and nighttime. Overall, the Gulf of Corinth seems to sustain high densities of mesopelagic fish that constitute the basic food resource for the abundant dolphin populations that inhabit the area.

A MSFD complementary approach for the assessment of pressures, knowledge and data gaps in Southern European Seas: The PERSEUS experience

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES.

Spatial distribution and life-history aspects of blackspot seabream Pagellus bogaraveo (Osteichthyes: Sparidae)

Spatial distribution and life history aspects of Pagellus bogaraveo in the eastern Ionian Sea were investigated using the data from 13 different studies carried out in the area from 1983 to 2010. The spatial patterns of the abundance, biomass and mean size showed that the species inhabits the shallow waters of the shelf (<170 m depth) as juveniles up to a certain size (<180 mm total length, LT ), moving to deeper waters of the slope (mainly 400-500 m depth) as adults. The spatial pattern of abundance indicated a continuous distribution of the species in deep waters, with hot-spot areas of high values, whereas in shallow waters distribution was more discontinuous, with higher concentrations of juveniles in estuaries and brackish waters. The study of biological aspects of the species revealed (1) a difference in the increase in mass between males and females, (2) protandrous hermaphroditism, accompanied by the presence of primary females and males that do not change sex, (3) a sex ratio in favour of females >250 mm LT , (4) the presence of hermaphrodites between 200 and 370 mm, (5) a long reproduction period from June to March, (6) a size at first maturity around 300 mm and (7) a diet composition of adults based mainly on fishes, and also on opportunistic behaviour in the food scarce environment of deep waters. The results suggest that the species' distribution and feeding strategies are the most appropriate for the oligotrophic eastern Ionian waters and that these conditions result in smaller sizes of the species in the east Mediterranean Sea compared to the west basin and the east Atlantic Ocean, with implications for the growth and reproductive biology of the species.

The circadian profile of extrasystolic arrhythmia: its relationship to heart rate and blood pressure

This paper aims at examining whether there is an association between the circadian patterns of systolic blood pressure, heart rate and the incidence of ventricular ectopic beats, as well as to confirm that reducing the blood pressure by a diuretic may also reduce the ectopic frequency. Thirty-four ambulatory patients with ventricular ectopic beats and a systolic blood pressure of 131.33 +/- 17.46 mmHg had a 24-hour Holter electrocardiographic and blood pressure monitoring following 1 week off any antiarrhythmic and antihypertensive treatment. Then they received for one week a standard diuretic combination (amiloride 5 mg + hydrochlorothiazide 50 mg) at a dose depending on their systolic pressure value and their monitoring was repeated. The mean hourly values of systolic blood pressure, heart rate and ventricular ectopic beats were "normalized", i.e. expressed as (x-x)/SD, taking each patient's 24-hour average as zero and his own standard deviation as the unit of measurement. As a group, there was an independent positive correlation between blood pressure and ectopic beats, while the heart rate was a nonsignificant negative factor for ectopic beats. On an individual level, however, an independent positive significant correlation between blood pressure and ectopic beats was found in only 8 cases, with a negative one in 4 cases. While the blood pressure of the group ranged symmetrically around its daily average value, the corresponding ectopic beat curve was highly asymmetric, with a very high incidence (up to 2.56 +/- 0.52 SD) for a rather short time (only 9.41 +/- 3.56 hours above average) and a low incidence (up to 1.26 +/- 0.49 SD) for the remaining 14.59 hours below average. Sudden rises in ectopic beat (greater than 1 SD/hour) occurred 1 to 6 times per day in each individual, significantly (P less than 0.01) more often (20.31%) with a high (greater than 1 SD) blood pressure than with a low (less than -1 SD) one (8.99%) with intermediate frequencies at intermediate pressures. After treatment with the diuretic, the systolic blood pressure was reduced, the heart rate increased and the ventricular ectopic beat incidence reduced (significant changes). The mean change in systolic pressure in 25 patients with a reduction in ectopy was a significant (P less than 0.01) decrease (-5.21 +/- 8.70 mmHg) while in the remaining 9 cases there was a non significant increase (+1.68 +/- 7.63 mmHg). The heart rate was higher in both subgroups.(ABSTRACT TRUNCATED AT 400 WORDS)