Algerian Coast Research Articles

Risk assessment of mercury and methyl mercury intake via sardine and swordfish consumption in Algeria

Total mercury (Hg) and methylmercury (MeHg) concentrations in the flesh of sardine (Sardina pilchardus) and swordfish (Xiphias gladius) fished in three Algerian coasts were determined by a direct mercury analyzer (DMA). We also assessed the risk to which the consumer was exposed to by calculating the estimated daily intakes (EDIs), target hazard quotient (THQ) and hazard index (HI). The average concentrations of Hg and MeHg in the flesh of sardine were similar (0.04 mg/kg wet weight) and in swordfish were 0.61 mg/kg wet weight; 0.57 mg/kg wet weight, respectively. These concentrations have not surpassed the thresholds set by the Algerian and European regulations. The estimated daily intakes for Hg and MeHg were similar in sardine (0.0064 μg/kg/day) and were 0.098 μg/kg/day and 0.092 μg/kg/day for Hg and MeHg, respectively, in swordfish. These values did not exceed the provisional tolerable weekly intake (PTWI) established by the European Food Safety Authority (EFSA) and by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). The target hazard quotient (THQ) and the hazard index (HI) calculated were < 1. Consequently, consumption of these fishes does not pose any risk for the adult groups of the Algerian population regarding mercury, and methylmercury studied.

Redescription and molecular characterisation of Allogastrocotyle bivaginalis Nasir & Fuentes Zambrano, 1983 (Monogenea: Gastrocotylidae) from Trachurus picturatus (Bowdich) (Perciformes: Carangidae) off the Algerian coast, Mediterranean Sea.

Allogastrocotyle bivaginalis Nasir & Fuentes Zambrano, 1983, the sole species of Allogastrocotyle Nasir & Fuentes Zambrano, 1983, was described from Trachurus lathami Nichols off Venezuela and never recorded since. We found monogeneans on Trachurus picturatus (Bowdich) (Carangidae) off the Algerian coast, Mediterranean Sea, which had the characteristics of the genus, including, especially, paired vaginae. We compared them to the single available specimen of A. bivaginalis, the holotype. Unfortunately, this holotype does not show clamp structure and soft internal anatomy. Our specimens were similar to A. bivaginalis in most characteristics such as body shape, vaginal openings, and number of testes, clamps and hooks in genital atrium. We detected minor differences in clamp structure but could not ascertain if these were the result of incomplete observations in the original description of real morphological differences. The host fish of our specimens were barcoded (cox1) confirming their specific identity. A phylogenetic analysis of cox1 sequences showed that our sequences of A. bivaginalis were distinct from those of Pseudaxine trachuri Parona & Perugia, 1889 (distance > 15%) and of several other gastrocotylids. Finally, we could not distinguish our Mediterranean specimens from A. bivaginalis, neither on the base of morphology (because the original description is incomplete) nor on molecules (because molecular information is lacking on A. bivaginalis from Venezuela) and ascribe them to A. bivaginalis. However, hosts are different, and localities are widely separated, so it is likely that future study will show that the species from the Mediterranean is a distinct, new, species.

Report on the Diatoms and Dinoflagellates Distribution along the Algerian Coasts: Inter-Region Comparison

The phytoplankton group's composition is an excellent indicator of the state of coastal waters. The aim of this study is to explore spatial variability of phytoplankton in shallow coastal areas from different regions (East, Center and West) of the Algerian coast. The quantitative and qualitative study of the phytoplankton population was conducted on samples taken during the 2012–2013 period by the research vessel GRINE BELKACEM. The qualitative results show a significant diversity of diatoms and dinoflagellates, which rank first and second in the total flora (Fr > 50%). This finding is also confirmed quantitatively by the abundance values in both 2013 and 2012 samples which largely exceeds the average value in most other areas of the western region (56%) and slightly exceeding 52% in all central areas which represent an equi-distribution between diatoms and dinoflagellates. The Dinoflagellates contribute significantly to the quantitative richness in the eastern region (>60%). The minimum value of Dia/Dino index, recorded in the eastern region confirms the dominance of the dinoflagellates especially in Skikda (0.31) (Skikda).However, our results reveal the presence, in smaller proportion, of other groups such as the cocolithophoridae and euglenophyceae.

The non-indigenous and invasive species Paraleucilla magna Klautau, Monteiro & Borojevic, 2004 (Porifera: Calcarea) in the Algerian coast (Southwestern of Mediterranean Sea)

The non-indigenous and invasive calcareous sponge Paraleucilla magna Klautau, Monteiro & Borojevic, 2004 has been detected for the first time on the Algerian coast. The species has been recorded at high abundance in Algiers Port (Algiers) and in Pisan Island (Béjaïa) during spring 2018. It was present from 2 m to 20 m of depth at the community of seaweeds with filter feeders established on artificial hard substrates and on rocky boulders. Total of 172 individuals were recorded not exceeding 5 cm in height. Anthropogenic activities such as aquaculture farms or shipping traffic might be important vectors or act as stepping-stones in further expansion of Paraleucilla magna.Additional recording of the species adds to the knowledge of its biogeography distribution, biology and ecology in the Mediterranean and may improve selection of key geographical sites for future monitoring on the species proliferation and expansion.

NEW RECORD OF GIANT DEVIL RAY (CHONDRICHTHYES: MYLIOBATIDAE) FROM ORAN BAY (WESTERN MEDITERRANEAN SEA)

The present paper reports a new record of Giant devil ray Mobula mobular (Bonnaterre, 1788) from western Algerian waters that is encountered for the first time in that coast since its first description in 1901 and last observation in late 80’s. This elasmobranch is categorized as endangered on the IUCN Red List (Endangered A2d ver 3.1) and is likely to be the rarest of the nine species of Mobula genus. Occasionally it is captured in Mediterranean Sea by purse seines, bottom and pelagic trawls, pelagic nets, bottom longlines, drifters and harpoons. The specimen stranded in “la Madrague Beach” in Western Algerian coasts. Its disc length was measuring 108.96 cm and disc width was 226.02 cm. This Myliobatidae is rarely seen with daily landed fish at Oran fishery. Up to date no explicit reason can be given for the strand of M. mobular but ghost fishing and important maritime traffic stay the most plausible cause of this incident.

Analysis and risk assessment of arsenic, cadmium and lead in two fish species (Sardina pilchardus and Xiphias gladius) from Algerian coastal water

ABSTRACTIn this study, the levels of arsenic (As), cadmium (Cd) and lead (Pb) have been determined in the flesh of two species of fish, sardine (Sardina pilchardus) and swordfish (Xiphias gladius) fished in the Algerian coast. Quantification of As, Cd and Pb was carried out using an ICP-MS method and the results were compared with the thresholds set by national and international regulatory bodies. In a further step, the risk to consumers was assessed using estimated daily intake (EDI), target hazard quotient (THQ) and hazard index (HI).The average concentration of As and Pb was higher in sardine (1.82; 0.10 mg kg−1 w.w., respectively), than in swordfish (1.10 mg kg−1 w.w.; not determined), whereas the concentration recorded for Cd was the same for both species (0.01 mg kg−1 w.w.). These concentrations are below maximum limits set in regulations. The THQs and HI were widely below 1. The consumption of these fish does not pose risk to the consumers.

British sharks in Sicily: records of long distance migration of tope shark (Galeorhinus galeus) from North-eastern Atlantic to Mediterranean Sea.

The study reports information about the recapture of two tagged adult females of tope shark, Galeorhinus galeus (Linnaeus 1758), in the central Mediterranean Sea (south coasts of Sicily) in 2014 and 2017. The two females were tagged in North-East Atlantic, respectively in Scotland in 2009 and Ireland in 2015. The Scottish specimen was a 175 cm female increasing of about 10 kg in body weight and 37 cm in total length during its 1967 days at liberty (5.39 years). The Irish one, was a pregnant female of an estimated age of 15-17 year which spent 248 days at liberty increasing 14 cm during this period. The growth rate of the two specimens was therefore between 6.8 and 7.8 cm year-1, faster than the annual increments of adults suggested in previous studies. Previous tope recapture records in the Mediterranean Sea were limited to the Alboran Sea, coast of Valencia and the Algerian coasts. The two tope females recaptured in the Strait of Sicily provided the first evidence of long distance entrance of NE Atlantic tope in the Mediterranean Sea. The well known occurrence of mature females and juveniles in this area of the Mediterranean suggest the hypothesis of a migration of adults female from their feeding grounds in north eastern Atlantic to lower latitudes up to the Mediterranean Sea for parturition.

The European pilchard Sardina pilchardus (Walbaum, 1792) stock off the western Algerian coast is fully exploited

The European pilchard Sardina pilchardus is one of the main target species of the commercial fishery along the Algerian coasts. To better understand the observed decline in catches we studied the state of exploitation and simulated the effect of changing fishing effort on the population of sardines. The Beverton-Holt yield-per-recruit model and the Thompson-Bell model showed that the stock is presently fully exploited. In order to estimate the required model parameters, a sample of 1234 specimens was obtained from commercial catches on the western Algerian coast. Analysis of otoliths and gonads allowed the estimation of age-length model parameters, length-weight relationship, length at first maturity, and length at 50% selectivity. In light of the high vulnerability of small pelagic species to environmental fluctuations one might consider to reduce the current level of exploitation to allow for the annual renewal of the exploitable stock of sardine in the western region of the Algerian coast, and hence for a sustainable yield on the long-term.

REGAT: A permanent GPS network in Algeria, configuration and first results

The REGAT (“REseau Géodésique de l'ATlas”) geodetic network is composed of 53 continuously–recording GPS stations distributed in the Algerian Atlas. It spans the whole width of the Algerian coast and reaches 300 km inland, with inter-sites distance of about 100 km. One additional site is located in Tamanrasset in the southernmost part of the country. The network, whose oldest stations started operating in 2007, encompasses the main active tectonic features of the most seismically active segment of the Nubia-Eurasia plate boundary in the Western Mediterranean. Here we describe the network configuration, the data collection and analysis strategy, as well as some preliminary results on horizontal GPS velocities. A detailed analysis of the velocity field in terms of plate boundary kinematics is the topic of a separate publication. The REGAT network fills an important gap in our knowledge of present-day plate boundary deformation in the Western Mediterranean. It will soon be enhanced by an additional 100 sites in order to improve deformation monitoring with a higher spatial resolution for a better assessment of the regional seismic hazard.

Species composition and distribution of Medusae (Cnidaria: medusozoa) in the Algerian coast between 2°e and 7°e (SW Mediterranean Sea)

The composition and abundance distribution of the Medusae community of the Algerian coast (between 2°E to 7°E) were investigated during autumn 2014. Zooplankton sampling was performed in the upper layer (0-100 m) at 14 stations. Fourteen species related to Hydromedusae and Scyphomedusae were identified. The Hydromedusae populations were represented by Leptomedusae (5 species), Narcomedusae (3 species), Trachymedusae (3 species) and Anthomedusae (2 species). Some species such as Cirrholovenia tetranema and Cunina globosa were newly recorded at the sampling areas. The total abundance of Medusae was under 10 individuals.m-3. Maxima of concentrations (> 4 ind.m-3) were localized at the central coast between Bou Ismail (2.6° E) and Algiers (3.2° E) Bays. Here, the populations of Aglaura hemistoma and Liriope tetraphylla were dominant (≈ 40%). A quantitative variability was showed between two populations groups (Liriope tetraphylla) and (Pelagia noctiluca and Rhopalonema velatum) characterized respectively the central region and the eastern region. Their distributions were analyzed in relation to environmental parameters (temperature, salinity, and chlorophyll-a) and the interaction with Copepods prey.

An ecological study on the distribu on of the fan shell Pinna nobilis Linnaeus, 1758 (Mollusca: Bivalvia) in the western Algerian coasts

Based on the fact that the Mediterranean sea is an existing place to the bivalves fan mussels of Pinna nobilis, the aim of this introductory study is to focus on understanding the nature of P.nobilis population density and its structure with an ongoing purpose to encourage future investigation of the subject matter to successfully uncover more ecological models; in order to reach the latter, a field-work took place from 2015 to 2018 in the Algerian west coasts on multiple sites with an end goal of better understanding the dynamics of the species, as well as assessing the effectiveness of protective measures of P.nobilis on the Algerian Western coastlines. The density, population structure and the growth of individuals noted on P.nobilis were examined through scuba diving along with multiple transects on the west coast of Algeria and measurements were executed on different spatial scales in populations occupying different sites; one of, is that of the protected naval area of “Habibas Island” in addition to other unprotected ones. . The results varied and they are as follows: the density of P. nobilis ranged from 0.28 in /m-2 on the transect to 0.08 in /m-2. The measured individuals were certainly a representative of their environment. The size of the P.nobilis did not prove itself to be prominent disturbance in the structure of the associated biota; the latter however showed that it was influenced by different areas. The outcomes of the study state that the recovery of the P. nobilis population on the west coast of Algeria was highlighted; stating the urgent need for setting security and protection of these species located on the Algerian West Coasts.

Density and ecological aspect of endangered limpet Patella ferruginea in the western Algerian coast: Implications for the Conservation

Density and ecological aspect of endangered limpet Patella ferruginea in the western Algerian coast: Implications for the Conservation

Microcotyle visa n. sp. (Monogenea: Microcotylidae), a gill parasite of Pagrus caeruleostictus (Valenciennes) (Teleostei: Sparidae) off the Algerian coast, Western Mediterranean.

Parasite biodiversity of fish of the southern part of the Mediterranean sea is still incompletely explored. We describe here Microcotyle visa n. sp. from the gill filaments of the bluespotted seabream Pagrus caeruleostictus (Valenciennes) (Sparidae) collected off the Algerian coast. The identity of fish hosts was confirmed by barcoding. Microcotyle visa n. sp. is herein described and illustrated. Analysis of the cox1 gene of the monogeneans revealed minor intraspecific variation (1.4%), an order of magnitude lower than the distance between this species and other Microcotyle species (10-15 %). Microcotyle visa n. sp. is distinguished from Microcotyle erythrini van Beneden & Hesse, 1863, a congener infesting sparids, on the basis of morphological (size of clamps, number of testes) and molecular (cox1) differences. This is the fourth member of the genus known to parasitise a sparid host. A species of Paramicrocotyle sp. included in the molecular analysis was nested within a robust Microcotyle + Paramicrocotyle clade; in the absence of demonstrated molecular and morphological differences, we consider that Paramicrocotyle Caballero & Bravo-Hollis, 1972 is a junior synonym of Microcotyle van Beneden & Hesse, 1863 and transfer two species of Paramicrocotyle as Microcotyle danielcarrioni (Martinez & Barrantes, 1977) n. comb. and Microcotyle moyanoi (Villalba & Fernandes, 1986) n. comb.

Glider data collected during the Algerian Basin Circulation Unmanned Survey

Abstract. We present data collected in the framework of the Algerian BAsin Circulation Unmanned Survey (ABACUS) project. The main objective of ABACUS is the monitoring of the basin circulation and of the surface and intermediate water masses' physical and biological properties in a key region of the Mediterranean Sea circulation. Data presented here have been collected through deep glider cruises in the Western Mediterranean Sea during the autumns of 2014, 2015 and 2016; activities at sea are expected to be repeated during the coming years, so that the dataset will be extended. Glider missions were conducted in the Algerian Basin, between the island of Mallorca and the Algerian coast. Across the three glider missions, eight repeated transects were completed which enabled us to investigate the basin-scale circulation and the presence of mesoscale structures, utilising both the adaptive sampling capabilities of the gliders and the higher resolution of the data. After collection, all data passed a quality control procedure and were then made available through an unrestricted repository host by the SOCIB Data Centre at https://doi.org/10.25704/b200-3vf5. The actual dataset spans three autumn seasons, providing an important contribution to the data collection in the chronically undersampled Algerian Basin. Temperature and salinity data collected in the first 975 m of the water column allowed us to identify the main water masses and describe their characteristics, improving the understanding of the dynamics of the region. On the timescale of the project, data show a large variability in the surface layer and reduced variability in the intermediate and deep layers. Our measurements have been successfully compared to data previously collected in the area from 1909 to 2011. Results showed similar overall distribution, ranges and variability to the historical data, with no outliers in the surface or deep layers.

The hidden side of a major marine biogeographic boundary: a wide mosaic hybrid zone at the Atlantic-Mediterranean divide reveals the complex interaction between natural and genetic barriers in mussels.

The Almeria-Oran Front (AOF) is a recognised hotspot of genetic differentiation in the sea, with genetic discontinuities reported in more than 50 species. The AOF is a barrier to dispersal and an ecological boundary; both can determine the position of these genetic breaks. However, the maintenance of genetic differentiation is likely reinforced by genetic barriers. A general drawback of previous studies is an insufficient density of sampling sites at the transition zone, with a conspicuous lack of samples from the southern coastline. We analysed the fine-scale genetic structure in the mussel Mytilus galloprovincialis using a few ancestry-informative loci previously identified from genome scans. We discovered a 600-km-wide mosaic hybrid zone eastward of the AOF along the Algerian coasts. This mosaic zone provides a new twist to our understanding of the Atlantic-Mediterranean transition because it demonstrates that the two lineages can live in sympatry with ample opportunities to interbreed in a large area, but they hardly do so. This implies that some form of reproductive isolation must exist to maintain the two genetic backgrounds locally cohesive. The mosaic zone ends with an abrupt genetic shift at a barrier to dispersal in the Gulf of Bejaia, Eastern Algeria. Simulations of endogenous or exogenous selection in models that account for the geography and hydrodynamic features of the region support the hypothesis that sister hybrid zones could have been differentially trapped at two alternative barriers to dispersal and/or environmental boundaries, at Almeria in the north and Bejaia in the south. A preponderantly unidirectional north-south gene flow next to the AOF can also maintain a patch of intrinsically maintained genetic background in the south and the mosaic structure, even in the absence of local adaptation. Our results concur with the coupling hypothesis that suggests that natural barriers can explain the position of genetic breaks, while their maintenance depends on genetic barriers.

Evaluation of a high-resolution wave hindcast model SWAN for the West Mediterranean basin

This study aims to present an evaluation and implementation of a high-resolution SWAN wind wave hindcast model forced by the CFSR wind fields in the west Mediterranean basin, taking into account the recent developments in wave modelling as the new source terms package ST6. For this purpose, the SWAN model was calibrated based on one-year wave observations of Azeffoune buoy (Algerian coast) and validated against eleven wave buoys measurements through the West Mediterranean basin. For the calibration process, we focused on the whitecapping dissipation coefficient Cds and on the exponential wind wave growth and whitecapping dissipation source terms. The statistical error analysis of the calibration results led to conclude that the SWAN model calibration corrected the underestimation of the significant wave height hindcasts in the default mode and improved its accuracy in the West Mediterranean basin. The exponential wind wave growth of Komen et al (1984) and the whitecapping dissipation source terms of Janssen (1991) with Cds = 1.0 have been thus recommended for the western Mediterranean basin. The comparison of the simulation results obtained using this calibrated parameters against eleven measurement buoys showed a high performance of the calibrated SWAN model with an average scatter index of 30% for the significant wave heights and 19% for the mean wave period. This calibrated SWAN model will constitute a practical wave hindcast model with high spatial resolution (˜3 km) and high accuracy in the Algerian basin, which will allow us to proceed to a finer mesh size using the SWAN nested grid system in this area.

Isolation, characterization and determination of biotechnological potential of oil-degrading bacteria from Algerian centre coast.

The Algerian coastline is exposed to several types of pollution, including hydrocarbons. The aim of this work was to isolate oil-degrading bacteria and to explore the intrinsic bioremediation potential of part of its contaminated harbour. A collection of 119 strains, capable to grow on mineral medium supplemented with hydrocarbons, were obtained from polluted sediment and seawater collected from Sidi Fredj harbour (Algiers). Twenty-three strains were selected for further studies. Sequencing of the 16S rRNA gene showed that most isolates belong to genera of hydrocarbonoclastic bacteria (Alcanivorax), generalist hydrocarbons degraders (Marinobacter, Pseudomonas, Gordonia, Halomonas, Erythrobacter and Brevibacterium) and other bacteria not known as hydrocarbon degraders (Xanthomarina) but were able to degrade hydrocarbons. Strains related to Marinobacter and Alcanivorax were frequently isolated from our samples and resulted the most effective in degrading crude oil. Screening of catabolic genes alkB and xylA revealed the presence of alkB gene in several bacterial strains; one isolate harboured both catabolic genes while other isolates carried none of the studied genes. However, they grew in the presence of crude oil implying the existence of other biodegradation pathways. The samples of seawater and sediment from the Algerian coast contain high level of hydrocarbon-degrading bacteria that could be interesting and useful for future bioremediation purposes. This investigation demonstrates the diversity of hydrocarbon-degrading bacteria from a marine-contaminated area in Algeria, and their variable biodegradation abilities.

Gonadal development and fecundity of bogue Boops boops (Linnaeus, 1758) (Sparidae) on the central Algerian coast

Boops boops sexuality was studied in 664 females, 201 males, and 103 hermaphrodites collected from central Algerian coast ports between December 2013 and November 2014. Histoanatomical observations were performed to describe the sexual pattern of B. boops . Observation of the evolution of sexual maturity stages as well as the gonadosomatic report have established the breeding period of B. boops as between February and June. The B. boops population fished here is in favor of females, with a percentage of 76.76% against 23.34% for males. Thus, the female to male ratio (F:M) of the sample was calculated as 1:3.3. According to the monthly value of hepatosomatic index, the bogue seems to store its reserves in the liver. The condition factor did not significantly fluctuate. The size at first sexual maturity for both sexes was determined as 14.74 cm total length. Fecundity was studied by the volumetric method in 149 mature females of between 13.9 and 29.4 cm in total length. Absolute fecundity varied between 36,600 and 445,200 oocytes per female. The average relative fecundity was 1 565 ± 228 oocytes per gram of body weight.

Age and growth of the axillary seabream (Pagellus acarne, Sparidae), in the central coast of Algeria, Mediterranean Sea

Age and growth of the axillary seabream (Pagellus acarne, Sparidae), in the central coast of Algeria, Mediterranean Sea

Evaluation of the heavy metals (mercury, lead, and cadmium) contamination of sardine (Sardina pilchardus) and swordfish (Xiphias gladius) fished in three Algerian coasts.

Aim:This study aimed to evaluate mercury (Hg), cadmium (Cd), and lead (Pb) levels in 70 samples of sardine (Sardina pilchardus) and 30 samples of swordfish (Xiphias gladius) fished in the Algerian coasts.Materials and Methods:After the mineralization of the fish samples through the pressure digestion, the analyses were carried out by inductively coupled plasma atomic emission spectroscopy.Results:Mean concentrations of Hg, Cd, and Pb in sardine were 0.62, 0.55, and 2.13 mg/kg wet weight, respectively, while in swordfish, the concentrations were 0.56, 0.57, and 3.9 mg/kg wet weight, respectively. These results exceeded the Algerian and European legislation threshold values, whereas Hg’s concentration in swordfish remained close to and did not exceed the recommended thresholds (0.56 mg/kg wet weight).Conclusion:This fish may represent a hazard for consumers in Algeria. Systematic and periodic controls of heavy metals in fish are recommended, and risk assessment is needed to protect the consumer.