scholarly journals Spatio-temporal distribution of soft-bottom epibenthic fauna on the Cilician shelf (Turkey), Mediterranean Sea

2007 ◽  
Vol 56 (4) ◽  
Author(s):  
Erhan Mutlu ◽  
Mehmev Betil Erguev
Keyword(s):  
Mediterranean Sea ◽  
Temporal Distribution ◽  
Soft Bottom ◽  
Spatio Temporal ◽  
Epibenthic Fauna

scholarly journals The spatio-temporal distribution of lightning over Israel and the neighboring area and its relation to regional synoptic systems

2011 ◽  
Vol 11 (8) ◽  
pp. 2125-2135 ◽  
Author(s):  
S. Shalev ◽  
H. Saaroni ◽  
T. Izsak ◽  
Y. Yair ◽  
B. Ziv
Keyword(s):  
Spatial Distribution ◽  
Mediterranean Sea ◽  
Temporal Distribution ◽  
Lightning Activity ◽  
Eastern Coast ◽  
Synoptic Situation ◽  
Lightning Flash ◽  
The Mediterranean ◽  
Spatio Temporal ◽  
Neighboring Area

Abstract. The spatio-temporal distribution of lightning flashes over Israel and the neighboring area and its relation to the regional synoptic systems has been studied, based on data obtained from the Israel Lightning Location System (ILLS) operated by the Israel Electric Corporation (IEC). The system detects cloud-to-ground lightning discharges in a range of ~500 km around central Israel (32.5° N, 35° E). The study period was defined for annual activity from August through July, for 5 seasons in the period 2004–2010. The spatial distribution of lightning flash density indicates the highest concentration over the Mediterranean Sea, attributed to the contribution of moisture as well as sensible and latent heat fluxes from the sea surface. Other centers of high density appear along the coastal plain, orographic barriers, especially in northern Israel, and downwind from the metropolitan area of Tel Aviv, Israel. The intra-annual distribution shows an absence of lightning during the summer months (JJA) due to the persistent subsidence over the region. The vast majority of lightning activity occurs during 7 months, October to April. Although over 65 % of the rainfall in Israel is obtained during the winter months (DJF), only 35 % of lightning flashes occur in these months. October is the richest month, with 40 % of total annual flashes. This is attributed both to tropical intrusions, i.e., Red Sea Troughs (RST), which are characterized by intense static instability and convection, and to Cyprus Lows (CLs) arriving from the west. Based on daily study of the spatial distribution of lightning, three patterns have been defined; "land", "maritime" and "hybrid". CLs cause high flash density over the Mediterranean Sea, whereas some of the RST days are typified by flashes over land. The pattern defined "hybrid" is a combination of the other 2 patterns. On CL days, only the maritime pattern was noted, whereas in RST days all 3 patterns were found, including the maritime pattern. It is suggested that atmospheric processes associated with RST produce the land pattern. Hence, the occurrence of a maritime pattern in days identified as RST reflects an "apparent RST". The hybrid pattern was associated with an RST located east of Israel. This synoptic type produced the typical flash maximum over the land, but the upper-level trough together with the onshore winds it induced over the eastern coast of the Mediterranean resulted in lightning activity over the sea as well, similar to that of CLs. It is suggested that the spatial distribution patterns of lightning may better identify the synoptic system responsible, a CL, an "active RST" or an "apparent RST". The electrical activity thus serves as a "fingerprint" for the synoptic situation responsible for its generation.

scholarly journals Spatio-temporal distribution of the dominant Diatom and Dinoflagellate species in the Bay of Tunis (SW Mediterranean Sea)

2005 ◽  
Vol 6 (1) ◽  
pp. 17 ◽  
Author(s):  
O. DALY YAHIA-KEFI ◽  
S. SOUISSI ◽  
F. GOMEZ ◽  
M.N. DALY YAHIA
Keyword(s):  
Mediterranean Sea ◽  
Chlorophyll Concentration ◽  
Temporal Distribution ◽  
Late Summer ◽  
Clear Correlation ◽  
Red Tides ◽  
Nutrient Inputs ◽  
Wide Range ◽  
Spatio Temporal ◽  
Diatom Blooms

Microphytoplankton composition and its relationships with hydrology and nutrient distributions were investigated over 24 months (December 1993 - November 1995) in the Bay of Tunis ( SW Mediterranean Sea). A new index, the ‘Specific Preference Index’ (SPI) obtained by computing the median value of each parameter weighed by the numerical value of each species density was developed. Using this index, the relationships between each species and temperature, salinity and major nutrients were analysed. The distribution of chlorophyll a did not show a clear correlation with microplankton abundance suggesting that other factors contribute to chlorophyll concentration, such as smaller phytoplankton size fractions or detritus. The winter-spring diatom blooms did not show a regular pattern during both years. High nutrient inputs in late summer, associated with mild meteorological conditions, contributed to the development of a large diatom bloom in autumn 1995 where significant silicate depletion was witnessed. Generally, diatoms were more stenotherm than dinoflagellates in the Bay, whereas dinoflagellates were more stenohaline than diatoms. The statistical analyses showed that the two species, Bellerochea horologicalis , and Lithodesmioides polymorpha, var., tunisiense, appeared in a wide range of environmental conditions. An excess of phosphateversus nitrate appeared to be associated with red tides of, Gymnodinium spp, whereas Peridinium quinquecorne, showed the opposite. Phosphate concentrations appear to be crucial in this coastal environment, where diatom blooms are often limited by low silicate availability.

Spatio-temporal sublittoral macrobenthic distribution and dominant species in Guanabara Bay, Rio de Janeiro, Brazil

2020 ◽  
Author(s):  
L. A. Pessoa ◽  
P. C. Paiva ◽  
R. R. Paranhos ◽  
C. A. Echeverría ◽  
Marcos A. V. Freitas
Keyword(s):  
Annual Cycle ◽  
Temporal Distribution ◽  
Distribution Patterns ◽  
Rainfall Regime ◽  
Guanabara Bay ◽  
Soft Bottom ◽  
Gravity Corer ◽  
Structural Variables ◽  
High Dominance ◽  
Spatio Temporal

Abstract Soft-bottom macrobenthic invertebrates are sensitive to natural or anthropogenic changes in aquatic ecosystems. The distribution patterns of sublittoral macrobenthic species in Guanabara Bay were studied from 2005 to 2007. Samples were collected at ten stations during six surveys throughout the rainfall regime (dry, early and late rainy). Ten replicates were collected at each station by Gravity corer or skin diving. Van Dorn bottles (bottom water) and by Ekman sediment sampler (granulometry) provided material for abiotic data. Stations were grouped into sectors (Entrance, Intermediary and Inner) based on abiotic data and location. The Redundancy Analysis (RDA) and Parsimonious RDA for all years and each annual cycle showed indicator taxa with high dominance in each sector. PERMANOVA indicated a regular seasonality between the surveys for the first annual cycle (p <0.05), and an atypical pattern for the second (p> 0.05), possibly due the low rainfall observed during this period. The mosaic of soft-bottom substrates infers structural variables, and patterns of temporal distribution were basically influenced by parameters those indicating pollution and the SACW (South Atlantic Central Water) intrusion, as well as ecological attributes among species, such as: predation, competition. The Ervilia concentrica and Cypridinidae could be used as indicators for anthropic and natural impacts in the Guanabara Bay for the Entrance sector, while Cyprideis salebrosa and Cyprideis sp. for the Intermediary sector and Heleobia australis for the Inner sector.

scholarly journals Spatio-temporal distribution of pufferfish (Tetraodontidae) along the Turkish coast of the Mediterranean Sea

2020 ◽  
Author(s):  
ERHAN MUTLU ◽  
ILARIA DE MEO ◽  
CLAUDIA MIGLIETTA
Keyword(s):  
Population Dynamics ◽  
Mediterranean Sea ◽  
Water Productivity ◽  
Marine Ecosystem ◽  
Ecological Status ◽  
Temporal Distribution ◽  
Ontogenetic Migration ◽  
The Mediterranean ◽  
Spatio Temporal ◽  
Lagocephalus Sceleratus

Pufferfish represent a serious threat to the marine ecosystem in the Mediterranean Sea. To better understand the population dynamics of pufferfish and their relation with ecological parameters, six pufferfish species were studied in two fishing and one non-fishing zone in one of the most oligotrophic regions of the Mediterranean Sea during 2014 and 2015, including different habitats of vegetated and non-vegetated and seasons. The results provide information on pufferfish ecological status compared with more eutrophic zones in which these species could potentially worsen their impact. Four species were common in the study area and two were rare. The dominant species was Lagocephalus suezensis, reaching abundances of 11,000 ind/km2 at 25 m in October, followed by Lagocephalus sceleratus, Lagocephalus guentheri, and Torquigener flavimaculosus. The rarest species, Tylerius spinosissimus and Sphoeroides pachygaster, reached higher abundance and biomass in October and February than the other sampling months. The riverine and meadow habitats played a crucial role for nursing and reproduction in the population dynamics of Lagocephalus species, while T. flavimaculosus was absent in these areas. Sex ratios changed depending on season and location. The occurrence of larger individuals of Lagocephalus spp. and T. flavimaculosus at greater depths evidenced an ontogenetic migration. Overall, length-weight (L-W) relationships indicate isometric growth for each of the species studied. Pufferfish populations were primarily a function of habitat and depth of seafloor and secondarily with water productivity.

scholarly journals Using opportunistic sightings to infer differential spatio-temporal use of western Mediterranean waters by the fin whale

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6673
Author(s):  
Estefanía Torreblanca ◽  
Juan Antonio Camiñas ◽  
David Macías ◽  
Salvador García-Barcelona ◽  
Raimundo Real ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Low Cost ◽  
Temporal Distribution ◽  
Western Mediterranean ◽  
Long Distance ◽  
Cetacean Species ◽  
Fin Whale ◽  
Gulf Of Lion ◽  
Fin Whales ◽  
Spatio Temporal

The fin whale (Balaenoptera physalus) is a cosmopolitan species with a resident population in the Mediterranean Sea. Due to its habitat, open seas often far from ports and airfields, and its long-distance migratory behaviour, studying and monitoring its distribution is costly. Currently, many opportunistic sightings (OS) reports are available, which provide a source of potentially useful, low-cost information about the spatio-temporal distribution of this species. Since 1993, the Spanish Institute of Oceanography has compiled a dataset comprising 874 records of OS of nine species of cetaceans in the western Mediterranean Sea and adjacent waters. The aim of this study was to use this dataset to investigate the differential use of these waters by the fin whale when compared with other cetaceans. We compared the presence of fin whales with the presence of any other cetacean species in the dataset. Binary logistic regression was then used to model these occurrences according to several spatio-temporal variables expected to reflect their habitat use. Several significant models reveal that fin whales are more prone than other cetaceans to use the waters over the slope of the Gulf of Lion in summer. This finding confirms that the Gulf of Lion is an area of importance for this species and suggests that the slope of the continental shelf could be particularly important. Our study shows how OS can be a source of useful information when appropriately analyzed.

scholarly journals Seasonal variation of microplastics density in Algerian surface waters (South-Western Mediterranean Sea)

2021 ◽  
Author(s):  
SKANDER SETITI ◽  
BOUALEM HAMDI ◽  
SAFIA CHERNAI ◽  
FOUZIA HOUMA BACHARI ◽  
SAMIR BACHOUCHE ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Temporal Distribution ◽  
Western Mediterranean ◽  
Additional Information ◽  
Western Mediterranean Sea ◽  
Wide Range ◽  
Algerian Coast ◽  
Spatio Temporal ◽  
Few Data ◽  
Harmful Effects

Coastal waters worldwide are widely contaminated with various-size plastics, whose presence in aquatic ecosystems has been shown to produce a wide range of economic and social impacts and harmful effects on marine ecosystems. While microplastics have been reported from many regions of the Mediterranean Sea, very few data exist regarding microplastics concentration in Algerian waters. In this study, we used a Manta trawl (330 µm) at six sampling stations in Bou-Ismail Bay, Algeria (South-West Mediterranean Sea) in order to provide novel information about the occurrence and composition of microplastics along the Algerian coast. Sampling was performed seasonally at six different sampling stations in 2018, providing additional information about the spatio-temporal variability of microplastics concentrations at the sea surface. Microplastics were found in all collected samples, with highly variable concentrations of 0.95, 0.88, 1.26, and 0.36 items/m3 in Autumn, Winter, Spring and Summer, respectively, and an overall mean concentration of 0.86 ± 0.35 items/m3. A classification based on the shape and appearance of microplastics indicated the predominance of fibers (32%), followed by fragments (27%), films (16%), foams (13%), and granules (12%). A qualitative microplastics analysis through Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) revealed that microplastics were mainly composed of polyethylene (68.2%), polypropylene (24.7%), polystyrene (4.1%) and other polymers (3%). These data provide an initial overview of the quantity, characteristics, and spatio-temporal distribution of floating microplastics in Bou-Ismail Bay (Algeria).

scholarly journals Spatial distribution pattern of European hake, Merluccius merluccius (Pisces: Merlucciidae), in the Mediterranean Sea

2020 ◽  
Vol 83 (S1) ◽  
pp. 21 ◽  
Author(s):  
Letizia Sion ◽  
Walter Zupa ◽  
Crescenza Calculli ◽  
Germana Garofalo ◽  
Manuel Hidalgo ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Additive Model ◽  
Temporal Distribution ◽  
Ecological Factors ◽  
Distribution Patterns ◽  
Merluccius Merluccius ◽  
Seasonal Thermocline ◽  
The Mediterranean ◽  
Spatio Temporal ◽  
European Hake

The present study provides updated information on the occurrence, abundance and biomass distribution patterns and length frequencies of Merluccius merluccius in the Mediterranean Sea, by analysing a time series of data from the Mediterranean International Trawl Surveys (MEDITS) from 1994 to 2015. The highest values of abundance and biomass were observed in the Sardinian Seas. The use of a generalized additive model, in which standardized biomass indices (kg km–2) were analysed as a function of environmental variables, explained how ecological factors could affect the spatio-temporal distribution of European hake biomass in the basin. High biomass levels predicted by the model were observed especially at 200 m depth and between 14°C and 18°C, highlighting the preference of the species for colder waters. A strong reduction of biomass was observed since the year 2009, probably due to the strengthening of the seasonal thermocline that had greatly reduced the availability of food. The general decrease in biomass of several stocks of anchovy and sardine, preys of European hake, might be indirectly connected to the decreasing biomass detected in the present study. The length analysis shows median values lower than 200 mm total length of most of the investigated areas.

scholarly journals Distribution of Mullus barbatus and M. surmuletus (Osteichthyes: Perciformes) in the Mediterranean continental shelf: implications for management

2002 ◽  
Vol 66 (S2) ◽  
pp. 39 ◽  
Author(s):  
George Tserpes ◽  
Fabio Fiorentino ◽  
Dino Levi ◽  
Angelo Cau ◽  
Matteo Murenu ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Random Sampling ◽  
Temporal Distribution ◽  
Stratified Random Sampling ◽  
Trawl Survey ◽  
Mullus Barbatus ◽  
Stock Recruitment ◽  
The Mediterranean ◽  
Spatio Temporal ◽  
Selection Of

The present work attempts to study the spatio-temporal distribution of Mullus barbatus and M. surmuletus in the Mediterranean Sea by using a time series of data from an international bottom trawl survey that covered a wide area of the Mediterranean Sea. The experimental surveys were accomplished annually from 1994 to 2000 on approximately 1000 pre-defined sampling stations distributed in 15 major areas. Selection of stations was based on a depth-stratified random sampling scheme that included five depth strata: 10-50, 50-100, 100-200, 200-500 and 500-800 m. The examined species were found throughout the studied region, mostly in depths down to 200 m. Abundance differences among major areas were found to be statistically significant and were attributed to the different exploitation patterns, as well as the different abiotic and biotic conditions prevailing in each area. Although both species undergo high fishing pressure, results did not demonstrate any decreasing trends in their abundance indices suggesting the existence of a good stock-recruitment relationship over the studied period. However, the dominance of young fish that has been found, makes the stocks highly vulnerable to recruitment changes; hence protection of spawning and nursery areas seems to be essential for their conservation.

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