This study aims to investigate the distribution of gelatinous zooplankton in relation to environmental parameters along the coastal regions of Algeria in the south-western Mediterranean Sea. A total ...of 48 species were recorded from nine sampling stations located in the central (Sidi Fredj) and western (Habibas Islands) sectors of the Algerian coast. The results showed that the seasonal distribution of gelatinous species exhibits significant variations. Amongst cnidarians,
,
and
are the most abundant species. Chaetognaths are primarily represented by
and
. Tunicates display high diversity, with
,
and
as the most abundant species. Lastly, in molluscs,
and
are the most abundant species. The nMDS and ANOSIM analysis reveal significant differences in the ecological community structures between the Habibas Islands and Sidi Fredj. Redundancy analysis results show relationships between different marine species and environmental variables, such as temperature, chlorophyll a and salinity. The studied species exhibit positive or negative correlations with these variables, suggesting an influence of these factors on their abundance and distribution. This study enhances our understanding of the factors that govern the distribution and dispersal of gelatinous zooplankton in the Mediterranean Sea and has significant implications for predicting changes in the distribution of these species under future environmental scenarios.
The objective of this study was to determine the population distribution and some biological aspects for fish stock assessment of the greater forkbeard
Phycis blennoides
along the Algerian basin. The ...distribution of
P. blennoides
(3418 individuals) was studied using data collected between 170–779 m depth during two bottom trawl surveys developed on 2003 and 2004. Additionally, some biological parameters were obtained from 1050 individuals sampled from commercial fisheries in Algerian ports (i.e. Annaba, Azeffoun, Dellys, Cap Djinet, Zemmouri, Bouharoun, Algiers, La Madrague, Cherchell, Tenes and Mostaganem) during the period 2013–2017.
P. blennoides
sampled from bottom trawl surveys showed a depth related distribution with the largest individuals being found at 600–800 m depth and the smallest at shallower depths. Density and biomass varied with depth and density also with longitude, while biomass showed no pattern with longitude. Recruitment was recorded in the eastern sector of Algeria during winter, for individuals sampled by bottom trawl surveys. Young
P. blennoides
entered commercial fisheries in summer, with an overall sex ratio skewed towards males (1F:2.18M). The size at first maturity (
L
50
) was 24.30 cm and 30.39 cm for males and females, respectively. The age at 50% maturity was 2–3 years for specimens collected by a bottom trawl survey in 2003 and commercial fisheries, but 3–4 years for the bottom trawl survey in 2004.
The diet of the greater forkbeard
(Brünnich, 1768) of the Algerian coast was studied between December 2013 and June 2015, providing information on its ecology for a better understanding of the ...feeding strategy. A total of 956 individuals, whose total length (TL) varied between 9.7 and 54.5 cm and weight (W) between 2.80 and 1334.11 g, were examined. The index of relative importance (%IRI), combining the three main descriptors of the presence of different ingested prey (%F, %N, %W), was used to characterize the relative importance of different food taxa. Qualitative and quantitative variations in diet were studied according to sex, size and seasons. The average annual digestive vacuity index (%V) was 5.51. It did not vary between seasons (x
= 5.43, x
= 7.82, α = 5%) and size (x
= 2.08, x
= 5.99, α = 5%), but was different between male (%V = 4.94) and female (%V= 12.78). Qualitative analysis of stomach contents reveals a fairly diverse range of predation with 1342 preys counted for a total weight of 462.84 g, which corresponds to an average number (AN) and weight (AW) of 3.03 and 1.04 g, respectively. This species feeds on benthic preys, composed mainly of natantia crustaceans (%IRI = 44.84) and teleost fish (%IRI = 2.61) with intraspecific preys (%IRI = 6.15). This cannibalism was frequent in specimens with a TL that exceeds 20 cm; it was even more frequent in females as well as in winter. Significant differences in feeding habits of
occurred according to sex, fish size and between seasons. The trophic level (TROPH) was high (3.66 < TROPH < 3.97), corresponding to carnivorous character.
The objective of this study was to assess the distribution patterns of dinoflagellates and ciliates communities during planktonic bloom and post-bloom development periods, in relation to ...environmental parameters. Their distribution was studied during spring and summer 2012, in coastal waters of Algeria at six sampling stations (four sampling layers). Overall, 116 species were identified, including 98 dinoflagellates. The species richness of microzooplankton was higher in summer (81 species: 67 dinoflagellates, seven tintinnids and seven ciliates) than in spring (76 species: 72 dinoflagellates, three naked ciliates and one tintinnid). Significant difference in total abundances was observed between spring (median = 145 ind l−1) and summer (median = 90 ind l−1) but no significance (P > 0.05, Mann–Whitney test) in Shannon–Wiener (H′spring: 3.31 bits ind−1; H′summer: 3.70 bits ind−1) and evenness (Espring: 0.77; Esummer: 0.84) indices. The ciliate average abundance was higher in summer (11.3 ind l−1) than in spring (1.95 ind l−1), whereas dinoflagellate average abundance was lower in summer (127.92 ind l−1) than spring (190.19 ind l−1). Non-metric multidimensional scaling was used to identify different sample assemblages. It showed that temperature and salinity influenced the distribution pattern in the canonical correspondence analysis followed by chlorophyll a, silicate and nitrate concentrations. Our framework provides insight regarding trait trade off with implications for feedbacks to ecosystems, aiming to bridge the gap of plankton community ecology in Algeria. It elaborates a taxonomic list of dinoflagellates and ciliates in the marine pelagic ecosystem and performs their ecological characterization in their environment.
The objective of this research was to study the effects of size and spat origin of farmed
in mussel longlines in the east of Bou-Ismail Bay (central coastal Algeria, south-western Mediterranean). The ...study was conducted from October 2017 to July 2020 in the east of Bou-Ismail Bay. The mussel spat were obtained from four origin sites (Tlemcen, Tenes, Ain Tagourait and the study site) and were seeded on three spat sizes (10–30, 30–60 and >60 mm). The production performance of this species was analysed on 284 random mussel plots using average physical product (APP), gain and loss rates, condition index (CI), percentage of edibility (PE) and shell thickness index (STI). Apart from the CI and loss rate, the performance indicators showed significant differences according to spat size and source (
< 0.05). Overall, the highest APP (4.3) was recorded for the small seeded mussels (10–30) mm and for those originating from Tlemcen, near finfish cages (APP = 4.14). These individuals exhibited more efficient growth and physiology for commercial size and performed better than the spat collected at the study site. The results can be considered a valid contribution to best farming practice for optimising the production of this species in Algeria. It also contributes to the development of integrated multitrophic aquaculture (IMTA) methodology, which is suitable for use in the oligotrophic Western Mediterranean.
This work provides useful knowledge on the reproductive traits and somatic growth of the white seabream (Diplodus sargus sargus Linnaeus, 1758) of the central sector of the Algerian coast. It aimed ...to estimate the maximum yield size of this sparid and evaluate its reproductive potential, by presenting the first results on its global fecundity. A total of 497 specimens, ranging in size from 12.4 to 40.3 cm, were monthly and randomly sampled from the artisanal fishery fleet, between January and December 2017. The obtained length-weight relationships indicated negative allometry for males (TW=0.024 TL2.842) and isometry for females (TW=0.016 TL3.013). The white seabream is a digynic protandrous hermaphrodite species. Sex reversal was observed with a large size overlap of 12 to 32 cm with a median of 23.5 cm. The reproductive season was observed from January to May and spawning occurred in spring. The size at first sexual maturity (TL50) was 20.55 cm for both sexes. Based on these results, the current legal minimum size of capture should be raised in the study area.
The aim of this paper was to report on an examination of the digestive organs in the deep-water fish
(Brünnich) from Algerian coastal waters. A total of 1,019 specimens (5.7–62.7 cm in total length) ...obtained from commercial fisheries were examined between December 2013 and May 2017. The anatomical study was conducted using morphometric measurements of different sections of the digestive tract of
. The histological features of the digestive tract were examined in the esophagus, stomach, intestine, and pyloric cecum. They were compatible with carnivorous feeding behavior and confirmed by a low intestinal quotient (IQ = 0.72 ± 0.13). The histopathological assessment highlighted the hepatic steatosis and parasitic infestation in its intestine from
, which also occurs in Algerian coastal waters. According to our knowledge, this paper reports for the first time the morphohistological analysis of the digestive tract of a Phycidae species in Africa and provides the first histopathological assessment of the digestive organs of the greater forkbeard in the southwestern Mediterranean Sea.
U razdoblju od prosinca 2013. do lipnja 2015. istraživan je sastav ishrane tabinje bjelice Phycis blennoides (Brünnich, 1768) na obali Alžira pružajući informaciju o ekologiji vrste te pridonoseći ...boljem razumijevanju strategije njenog hranjenja. Analizirano je ukupno 956 primjeraka čija je totalna dužina (TL) varirala između 9,7 i 54,5 cm i mase (W) između 2,80 i 1334,11 g. Za obilježavanje relativne važnosti različitih taksona u progutanoj hrani, korišten je indeks relativne važnosti (%IRI) kombinirajući tri glavna deskriptora prisustva različitog progutanog plijena. Kvalitativne i kvantitativne varijacije u ishrani proučavane su prema spolu, veličini i godišnjim dobima. Prosječni godišnji indeks praznine crijeva (% V) je bio 5,51. Nije varirao između sezona (χ²cal = 5,43, χ²th = 7,82, α = 5%) i veličine (χ²cal = 2.08, χ²th = 5,99, α = 5%), ali je bio različit između mužjaka (%V = 4,94) i ženki (%V= 12,78). Kvalitativna analiza sadržaja želudca otkriva prilično raznolik raspon predacije s izbrojana 1342 plijena ukupne mase 462,84 g što odgovara prosječnom broju (AN) i masi (AW) od 3,03 odnosno 1,04 g. Ova vrsta se hrani bentoskim plijenom, uglavnom sastavljenim od rakova plivača (natantia) (% IRI = 44,84) i riba košunjača (% IRI = 2,61) te s intraspecifičnim plijenom (% IRI = 6,15). Ova pojava kanibalizma je česta kod primjeraka s TL koja premašuje 20 cm a još je češća kod ženki u zimskom periodu. Značajne razlike u prehrambenim navikama P. blennoides javljaju se prema spolu, veličini ribe i godišnjim dobima. Trofička razina (TROPH) bila je visoka (3.66 <TROPH <3.97), što odgovara karnivornom karakteru vrste.
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