Boughrara Lagoon Research Articles

Discriminant inter and intrapopulation variation in sagittal otolith shape and morphometry inChelon ramada(Actinopterygii, Mugilidae) from the Boughrara and El Bibane lagoons in Tunisian waters

AbstractVariations in sagittal otolith shape and morphometry, including length (Lo), width (Wo), area (Ao), and perimeter (Po), were investigated in two populations ofChelon ramadacollected from the Boughrara and El Bibane lagoons located in southeastern Tunisia. The objective was to assess the geographic variation in the sagittal otoliths' shape and morphometry and the effect of potential fluctuating asymmetry (FA) in morphometry on the stock structure ofC. ramadain the two lagoons to inform on appropriate management procedures. At the interpopulation level, analysis of sagittal otolith shape showed a statistically significant difference (P= 0.0001), i.e. there was a bilateral asymmetry, in the shape of left and right otoliths between individuals of the two populations. In addition, significant FA was found only inLobetween the left and right otoliths. At the intrapopulation level, a significant shape difference (P< 0.0001), particularly asymmetry, was observed in both left and right otoliths between males and females, indicating sexual dimorphism in shape within the Boughrara lagoon. However, significant shape similarity, i.e. symmetry, was observed in the left and right otoliths among individuals of the El Bibane lagoon. Moreover, a significant FA was detected inLobetween the left and right otoliths only among males, as well as between males and females of the Boughrara lagoon. However, a significant FA between the left and right otoliths was found only inWoamong males and in all morphometric dimensions among females andWobetween males and females of the El Bibane lagoon. Discriminant function analysis of the otolith contour shape confirmed the presence of two separateC.ramadastocks, one corresponding to the Boughrara lagoon and the other representing the El Bibane lagoon, which should be managed separately. The possible cause of morphological variation in the sagittal otoliths' shape and morphometry due to FA between individuals of the two populations was discussed in relation to the biotic and abiotic factors.

Sediment quality and environmental risk assessment in a Mediterranean coastal system using geochemical and multivariate statistical analyses: the case of Boughrara Lagoon (southeastern Tunisia)

Coastal ecosystems are the most vulnerable to natural and anthropogenic pressures which should be assessed using various chemical and ecological indicators. Our study aims to provide practical monitoring of anthropogenic pressures related to metal discharges in coastal waters for identifying potential ecological deterioration. The spatial variability of various chemical elements concentrations and their main sources were determined in the surficial sediments of a Mediterranean coastal area submitted to high anthropogenic pressure, the semi-enclosed Boughrara Lagoon located in southeastern Tunisia, by conducting several geochemical and multi-elemental analyses. The grain size and the geochemical analyses both suggested a marine influence of the sediment inputs in the north of the area (near Ajim channel), whereas continental and aeolian features dominated the sedimentary inputs in the southwestern lagoon. This last area was also characterized by the highest concentrations of metals, in particular Pb (4.45-173.33ppm), Mn (68.45-1469.27ppm), Cu (7.64-134.26ppm), Zn (28.74-244.79ppm), Cd (0.11-2.23ppm), Fe (0.5-4.9%), and Al (0.7-3.2%). By referring to background crustal values and the contamination factor calculations (CF), the lagoon is considered as highly polluted for Cd, Pb, and Fe (3 < CF < 6). Three possible sources of pollution were identified: phosphogypsum effluents (P, Al, Cu, and Cd), the ex-Pb mine (Pb and Zn), and the cliff weathering and streams input from the red clay quarry (Fe). Furthermore, pyrite precipitation was identified for the first time in the Boughrara lagoon, suggesting the occurrence of anoxic conditions in this lagoon.

Marine Biotoxin Profile and Karenia selliformis and Alexandrium minitum Occurrence in Boughrara Lagoon During the Last Decade

Abstract As part of the routine control of the Tunisian network for the monitoring of the most problematic microalgae species Karenia selliformis and Alexandrium minutum and for the study of hydrophilic and lipophilic marine biotoxin profiles, clams and seawater samples from Boughrara lagoon were analysed during the past decade. The results showed that the abundance of Karenia selliformis and Alexandrium minutum in the Boughrara lagoon exhibited significant variability at annual scales. K. selliformis was recorded in all sampling years with interannual variability. Among the nine sampled years, 2010, 2012, 2016 and 2017 were, respectively, the most significant in terms of mean abundance (2.85, 2.42, 1.38, 1.69) ∙ 105 cells L–1. A. minutum species were observed in the water column during all investigated years except in 2013, 2016 and 2017, but in low concentrations compared to K. selliformis (≤ 7.4 ∙ 102 cells L–1). Using LC-FLD, traces of paralytic toxins (C1 and GTX-2) were detected in some clam samples. Their concentrations were largely below the regulatory limit. For the first time, N-sulfocarbamoyl gonyautoxin-2 (C-1) and gonyautoxin 2 (GTX-2) were detected in some clam samples from this region. LC-MS/MS analysis confirmed the presence of gymnodimines in some samples. The main peak corresponds to the GYM-A with high concentrations generally above 1 mg kg–1 of clams meat, which confirms the persistence of this neurotoxin in Boughrara lagoon.

Mobility of trace metals and microbiological pollution from dredged sediments to the Gulf of Gabes, Tunisia.

Sediments are periodically dredged from the major ports in the Gulf of Gabes (GG) during maintenance operations. These sediments are dumped near the coats of Sfax and Gabes cities. In the present study, 6 trace metals (Cd, Cu, Cr, Ni, Pb, and Zn) concentrations were assessed in both sediments and column water taken from the different basins of Sfax port. This study is the first to focus on the microbial and microalgae contaminations of Sfax port sediments. The spatial distributions of trace metals in dredged sediments from the different basins of Sfax port show that the maximum concentrations of Cd (13.75µg/g), Cu (892.5µg/g), and Zn (1447µg/g) exceeded the Geode standard thresholds. The same elements, also detected in the water column, exceeded the toxicity thresholds for phytoplankton, shellfish, and algae (Cd 0.095µg/l, Cu 4.52µg/l, and Zn 37µg/l). The presence of coliforms, indicators of sewage pollution, as pathogenic germs (Pseudomonas), was shown through microbiological examinations of the sediments and water column. The microalgae enumeration showed the abundance of dinoflagellate cysts (stressed form) which attests to the presence of severe conditions in Sfax port. Different toxic species were identified as Prorocentrum lima and Alexandrium minutum. The same trace metal sources and abundance in Sfax port and GG sediments suggest the hypothesis of their transfer from their disposal sites in coastal areas to deeper depths in the GG and until Boughrara lagoon (BL). As trace metals, microalgae species were also transferred by hydrodynamic currents inside the GG where they found suitable conditions to their proliferation causing the seawater coloration phenomenon, eutrophication, and degradation of the aquatic system.

Interspecific and intersexual variability of the sagitta otolith shape between Liza aurata and Chelon ramada (Mugiliformes: Mugilidae) inhabiting the Boughrara lagoon, Tunisia

Interspecific and intersexual variability of the sagitta otolith shape between Liza aurata and Chelon ramada (Mugiliformes: Mugilidae) inhabiting the Boughrara lagoon, Tunisia

The influence of environmental characteristics on the distribution of ciliates in two coastal areas in the Eastern Mediterranean Sea (Gulf of Gabes, Tunisia)

Spatial variability of ciliates in relation to chlorophyll a, nutrients, and environmental variables were studied in lagoon (Boughrara lagoon) and marine ecosystems (Ghannouch coast) in the surface layer and at the water–sediment interface during autumn. Results revealed a striking difference between the two ecosystems, with higher nutrient concentrations at the Ghannouch coast, except for ammonium. Ciliate abundance was five to six times higher in the lagoon (123.43–126.80×102cellsl−1) than at the marine coast (21.80–24.50×102cellsl−1) (ANOVA, P < 0.001). Loricate ciliate attained high abundance in Boughrara lagoon (88%–90% of total ciliates abundance) and decreased at Ghannouch coast (44%–51% of total ciliate abundance). The species richness of the loricate ciliates was higher in Boughrara lagoon (68 taxa at both surface layer and water–sediment interface) than at Ghannouch coast (32 taxa at the surface layer and 23 taxa at the water–sediment interface). Naked ciliates were poorly represented (10%–12% of the total ciliate abundance) in the lagoon stations but had substantial percentages (49%–56% of the total ciliate abundance) at Ghannouch coast. The spatial distribution patterns of ciliate communities at both sites were strongly influenced by nutrient heterogeneity. Small species (naked ciliates) are favoured by higher nutrient concentrations at Ghannouch coast, whereas the contribution of large species (loricate ciliates) increased with the lower nutrient concentrations in Bouhgrara lagoon. It has been suggested that nutrient changes could drive shifts in ciliate community structure and abundance. The deteriorated water quality of the Ghannouch coast likely induces the low loricate ciliate abundance and diversity and the higher relative abundance of naked ciliates compared to the less polluted Boughrara lagoon.

Spatial variations of planktonic ciliates, predator-prey interactions and their environmental drivers in the Gulf of Gabes-Boughrara lagoon system

Spatial variability of ciliates in relation to environmental variables and abundance of heterotrophic prokaryotes, picoeukaryotes, nanoeukaryotes, microphytoplankton and mesozooplankton were studied in the Gulf of Gabes- Boughrara lagoon system in the surface layer and at the water-sediment interface between 9 and April 15, 2017. Results revealed a striking difference between the two ecosystems, with higher temperature and salinity and high availability of nitrite and total nitrogen concentrations in the Boughrara lagoon, probably generated by limited exchanges of water with the Gulf of Gabes associated with disturbed areas in the lagoon. Ciliates abundance was slightly higher in the Gulf of Gabes (16–19 × 102 cells l−1) than in the Boughrara lagoon (13–16 × 102 cells l−1), but the species richness was significantly higher in the Boughrara lagoon (40 taxa in the surface layer and 35 taxa at the water-sediment interface) than in the Gulf of Gabes (35 taxa in the surface layer and 33 taxa at the water-sediment interface). The ciliate community was characterized by the predominance of Spirotrichea. Tintinnids were more abundant than naked ciliates in both sampled ecosystems, except in a few stations. Some tintinnid species, such as Tintinnopsis radix, T. nana and T. parvula, showed high abundance, indicating their tolerance to environmental pollution. The dominant species T. beroidea, T. nana and Strombidium compressum showed significant relationships with nutrient concentrations, illustrating their affinity for highly eutrophic sites. Regression and correlation analyses suggest food dependence of Spirotrichea and tintinnids up on picoeukaryotes, whereas naked ciliates appeared more controlled by the availability of nanoeukaryotes and microphytoplankton. Metazooplankton abundance showed no significant relationships with ciliate abundance.

Zooplankton abundance and community structure driven by tidal currents in a Mediterranean coastal lagoon (Boughrara, Tunisia, SW Mediterranean Sea)

Lagoons and coastal marine zones are very productive and useful ecosystems, but they are threatened by the effects of global change and anthropogenic pressures. These effects have a negative impact on the zooplankton, weakening its function of phytoplankton consumer, leading to uncontrolled proliferation of microalgae in case of eutrophication. In this study we test the hypothesis that tidal exchanges with the sea can counteract these deleterious effect, by renewing the zooplankton community and by enhancing its top-down control of phytoplankton through selective retention of zooplankton grazers. Our study focused on the southern region of the Gulf of Gabes and the Boughrara lagoon which presents the highest tidal range in the Mediterranean. During two field campaigns (October 2016 and April 2017) we have analyzed zooplankton descriptive (taxonomic composition, abundance; biomass) and functional (ingestion rate, grazing pressure) variables and environmental variables during time series at a fixed station during ebb-flood sequences and at 8 stations along a sea-lagoon transect and during different tidal amplitude periods. Multivariate analyses of both environmental parameters and zooplankton taxa showed the existence of three distinct zones along the sea-lagoon transect, but also the influence of tidal circulation and water mixing on the renewal of the zooplankton community up to the innermost zones of the lagoon. Time series gave clear patterns for the input/output of marine/lagoon species and show a net import for different taxa and for the total zooplankton abundance and biomass (mean flood/ebb ratio = 2.2 for the total abundance and 2.4 for the biomass), leading to differential retention of zooplankton in the lagoon and to an increase in the potential grazing pressure on phytoplankton (mean flood/ebb ratio = 2.8). We also estimated that the grazing pressure in the lagoon was twice higher during the periods of high tidal amplitudes (at or close to spring tide) compared to periods with low amplitude (neap tides), clearly showing that the retention of zooplankton significantly increases the grazing impact on phytoplankton. These results highlight the importance of the tidal forcing for maintaining the good status of the zooplankton structure and function in strongly anthropized coastal and lagoon ecosystems.

Using a naive Bayes classifier to explore the factors driving the harmful dinoflagellate Karenia selliformis blooms in a southeastern Mediterranean lagoon

The blooms of the toxic dinoflagellate Karenia selliformis can be predicted with accuracy derived from knowledge of the main forcing variables. A naive Bayes classifier modeling framework, a member of the Bayesian network family, is used to identify the phytoplankton community and the physical and meteorological parameters involving K. selliformis blooms in the eutrophic Boughrara Lagoon (BL), Tunisia. The proposed model takes into account the physical environment parameters (salinity, water temperature, tide amplitude), meteorological constraints (evaporation, air temperature, insolation, rainfall, atmospheric pressure, and humidity), phytoplankton groups (diatoms, dinoflagellates, cyanobacteria, Euglenophyceae), and the sampling months on K. selliformis blooms. The shift to highest salinity and atmospheric pressure, associated with reduced tide, are the most favorable conditions for K. selliformis blooms in BL. The results show that K. selliformis formed nearly monospecific blooms. A shift in species composition was pointed out between the bloom and non-bloom conditions. The Euglenophycea and some dinoflagellates like Peridinium minimum, Prorocentrum minimum, Prorocentrum micans, Prorocentrum gracile, Protoperidinium minutum, and Scrippsiella trochoidea appeared during blooms, whereas diatoms, diazotrophic cyanobacteria, and dinoflagellates (Akaskiwo sanguinea, Karlodinium veneficum, Gyrodinium spirale, Oxyrrhis marina, Polykrikos kofoidii) were observed under non-bloom conditions. This study highlighted the most favorable physical and meteorological conditions for K. selliformis bloom occurrences and also pointed out species indicators for bloom establishment and others for non-bloom conditions. Monitoring the dynamics of these species with the associated physical and meteorological variability offers valuable information to plan for the best options for prediction of potentially toxic blooms of K. selliformis and associated dystrophic consequences.

Dinoflagellates encystment with emphasis on blooms in Boughrara Lagoon (South-Western Mediterranean): Combined effects of trace metal concentration and environmental context

Resting cysts (RCs), vegetative cell abundance, sediment characteristics, nutrient and trace metal concentrations were investigated in fifteen stations at Boughrara Lagoon during October and November 2016. Twelve morphotypes of RC were recorded. The sampling sites showed a similar cyst assemblage trend but differed in total cyst abundance. The cysts of heterotrophic dinoflagellates dominated over the cysts of autotrophic dinoflagellates throughout the study area and were correlated to the abundance of Bacillariophyceae explained by a likely trophic relationship. The abundance of cysts was positively correlated to phosphorus concentrations measured in the sediment. As well, cysts of Polykrikos kofoidii and Scrippsiella trochoidea were significantly correlated to nitrogen concentrations in water column. The trace metal concentrations did not show any effect on cyst abundances in most cases, except for Cr on mixotrophic dinoflagellates, suggesting that metal contamination is not determinant in the encystment of dinoflagellates. Autotrophic dinoflagellates cyst abundance was dependent on sediment characteristics with the highest densities being recorded in muddy sediments. The hydrodynamics of the lagoon, characterized by a weak water circulation and a low water renewal in the South-Western zone, was considered among the environmental factors most affecting RC distribution. The dominance of potentially toxic species cysts highlights the necessity of monitoring these forms suspected to constitute the precursor of toxic blooms in this area.

Nesting Parameters of the Little Egret (Egretta garzetta) in Boughrara Lagoon, Southeastern Tunisia

Investigating the breeding ecology of waterbirds in the Mediterranean is essential for understanding their population dynamics and for conservation purposes. Here, the reproductive parameters of the Little Egret (Egretta garzetta) were investigated in Boughrara Lagoon, a poorly known breeding area in southeastern Tunisia. In total, 152 nests were monitored April-July 2014 from egg-laying to hatching. The nesting period extended from late April to late June, showing three distinct peaks. All nests were constructed < 2 m from the ground in nitre shrubs (Nitraria retusa). Clutch size ranged from 2 to 5 eggs, with a modal clutch of 4 eggs. Average egg volume (± SE) was 25.11 ± 0.08 cm3, which is within the range of known values for the species studied. Using the Mayfield method, hatching rate was estimated at 71%. Our results showed that clutch size and hatching success decreased as the breeding season progressed. This seasonal decrease in breeding performance is in agreement with the general trend in waterbirds and could be explained by the poorer quality of late breeders compared to early ones, or alternatively to the deterioration of environmental conditions late in the breeding season.

Using general linear model, Bayesian Networks and Naive Bayes classifier for prediction of Karenia selliformis occurrences and blooms

The prediction of the dinoflagellate red tide forming Karenia selliformis is a relevant task to aid optimized management decisions in marine coastal water. The objective of the present study is to compare different modeling approaches for prediction of Karenia selliformis occurrences and blooms. A set of physical parameters (salinity, temperature and tide amplitude), meteorological constraints (evaporation, air temperature, insolation, rainfall, atmospheric pressure and humidity), sampling months and sampling sites are used. The model prediction included general linear model (GLM), Bayesian Network (BN) and the simplest BN type which is, Naive Bayes classifier (NB). The results showed that three models incriminated high salinity in Karenia selliformis blooms and the sampling sites, mainly Boughrara lagoon, in the occurrences. The BN performed better than linear models (NB and GLM) for both Karenia selliformis occurrences and blooms prediction. This later is related to the facts that BN considered the inter-independency between predictive variables and that the relationships between the variables and the outcome are often non-linear such us; the transition to bloom situations appeared to be triggered by a salinity threshold. This study is useful in the management of this ecosystem so as to use the best disposal options in the early prediction of the toxic blooms.

High-resolution numerical modelling of the barotropic tides in the Gulf of Gabes, eastern Mediterranean Sea (Tunisia)

A high-resolution 2D barotropic tidal model was developed for the Gulf of Gabes and used to characterise hydrodynamic processes and tidal dynamics. The model is based on the Regional Ocean Modelling System. It is forced at the open boundaries by the semidiurnal M2 and S2 astronomical components while meteorological forcing has been neglected. The model results show good agreement with observations confirming that it reproduces the gulf's main tidal characteristics reasonably well. In fact, the simulated semidiurnal tidal components M2 and S2 generate important sea level variations and coastal currents. Tidal propagation is directed to the gulf's western sector while tidal resonance occurs in its inner sector where the M2 and S2 amplitudes are about 50 and 36 cm, respectively. Phase maxima (170°–185°) are located inside Boughrara Lagoon for both the simulated M2 and S2 tides. The strongest currents are found in shallow coastal regions and at the lagoon's western inlet. During spring tides, currents are around 10–20 cm s−1 in the gulf center and up to 50 cm s−1 inside the lagoon.

First report of the invasive species Branchiomma bairdi McIntosh, 1885 (Annelida: Sabellidae) along the Tunisian coast (Mediterranean Sea)

The invasive sabellid polychaete Branchiomma bairdi McIntosh, 1885 was collected in the Boughrara Lagoon (southern Tunisian coast) between 2012 and 2013. This species was originally described from Bermuda and has been widely reported in the Caribbean Sea. It has been considered as non-indigenous species on the Pacific coast of Panama and the California Gulf. Recently, B. bairdi was recorded along the Italian and Turkish coasts, Australia, Canary and Madeira Islands. It was suggested that the commercial shipping is the most likely vector for the introduction of the species to Mediterranean Sea. A description of the species along with a discussion of its systematic position and ecology are provided.

Structuring factors of the spatio-temporal variability of macrozoobenthos assemblages in a southern Mediterranean lagoon: How useful for bioindication is a multi-biotic indices approach?

The authors investigated the impact of the extension of the El Kantra Channel on the composition and structure of macrobenthic assemblages in Boughrara Lagoon (Gulf of Gabes, Tunisia along with the use of 4 biotic indices (AMBI, BENTIX, M-AMBI and TUBI). Thirteen stations were sampled seasonally in 2012–2013. Forty-one species were found in 2012–2013 not recorded in 2009–2010, including 20 species of polychaetes belonging to the trophic groups of deposit-feeders and carnivores which are expected to increase in areas disturbed by organic pollution. During the survey, we recorded a high fish mortality, essentially caused by the development of harmful algal blooms (HAB) which increased organic matter deposition, thus inducing polychaete development. This seems to weaken the bio-indicating power of biotic indices used here which, paradoxically, classified all sampled stations at a high ecological status. A review of these indices and their applicability to all marine environments is recommended.

Assessment of surface sediment dynamics and response of benthic macrofauna assemblages in Boughrara Lagoon (SW Mediterranean Sea)

A study was conducted in the spring of 2009, the winters of 2010 and 2013, and in the summer of 2012 at 13 stations in Boughrara Lagoon, Tunisia (southern Mediterranean). The country⿿s largest lagoon, it is considered to be an anthropogenically stressed area, though a major tourist centre⿿Djerba Island⿿is located along its northern shores. The lagoon bottoms were studied via analyses of grain size, surface sediment composition, total organic matter (TOM) and through the trophic and functional organisation of benthic macrofauna. The results indicate that the bottoms are composed of fine, medium or coarse sands and that sediment distribution is controlled by water movement. Estimation of TOM content revealed that the studied samples present both normal and imbalanced sediments. The structure and organisation of the lagoon⿿s benthic macrofauna are dominated by select deposit feeders and underwent significant changes during the period 2010⿿2013.Subjected for decades to increased pollution due to growing human activities in the surrounding area, Boughrara Lagoon now appears to be impacted by certain environmental/anthropogenic stressors, as indicated by the presence of pollution-tolerant bio-indicator species in the imbalanced area. The response of the lagoon ecosystem to changes in benthic sediment deposition provides a potential assessment tool for similar habitats elsewhere.

First record of Naineris setosa (Verrill, 1900) (Annelida: Polychaeta: Orbiniidae) in the Western Mediterranean Sea

The Polychaeta Naineris setosa (Verrill, 1900) is reported for the first time in the Western Mediterranen Sea. Several specimens were collected in 2012 and 2013 in Boughrara Lagoon (Tunisia). The vector of introduction of N. setosa likely commercial shipping because Gabes is an international harbour with dense shipping traffic. A detailed description of specimens from Boughrara Lagoon is provided in this paper.

Factors determining the dynamics of toxic blooms of Alexandrium minutum during a 10-year study along the shallow southwestern Mediterranean coasts

Many blooms of the toxic dinoflagellate Alexandrium minutum have been recorded since 1990 in the Gulf of Gabes (southwestern Mediterranean Sea). To understand the determining factors of bloom formation, we studied the distribution of A. minutum in relation to environmental factors in samples taken at shallow sandy (<1 m) beach stations and a lagoon between 1997 and 2006. This was accompanied by laboratory experiments to identify A. minutum. The species forms harmful algal blooms (HABs) in stations subjected to anthropogenic eutrophication and in confined lagoons, living under conditions of varying salinity which gives it a unique opportunity to broaden its physiological tolerance and increase its colonisation potential. Increases in phosphorus appear to be more important than nitrogen or temperature in the control of A. minutum. The stations sampled all along the coast present specific hydrographic properties (shallowness, turbulence) suggesting that factors other than temperature and nutrients influence Alexandrium distribution, the exception being Boughrara Lagoon where the species developed in accordance with published data. Our findings and their interpretations indicate that the mechanism of the sudden A. minutum blooms along the nearshore of the Gulf of Gabes was complex and differed from that of true coastal ecosystems.

Anthropogenic and natural effects on the water and sediments qualities of costal lagoons: case of the Boughrara Lagoon (Southeast Tunisia)

The Boughrara Lagoon located in southern Tunisia shows evidence of eutrophication and the deterioration of water quality. The large amount of water shown to exchange tidally between the lagoon and the open sea suggests that while water per se is important and observed eutrophication problems are not caused by a lack of water. Heavy metal concentrations in surface sediments of the lagoon indicate that the ecosystem degradation is most likely related to the discharge of untreated phosphogypsum. Excessive pumping from the local freshwater aquifer that previously supplied freshwater to the lagoon via sub-aquatique fractures is likely to be a significant factor contributing to the water and sediment quality degradation of Boughrara Lagoon.

Reproductive activity in the commercially exploited mediterranean muricid Hexaplex trunculus collected from Boughrara lagoon (Southern Tunisia)

The banded murex Hexaplex trunculus (Linnaeus, 1758) is a commercially exploited gastropod in the Mediterranean region including Tunisia where it has become an important fishery resource these last years. In the present investigation, some reproductive aspects of this species were described in the population of Boughrara lagoon based on macroscopic examination of the gonads (gonadic conditional indices) together with observation of the seasonal hypertrophy of the penis in males and capsule gland in females. This procedure of assessing reproductive activity was validated by field observations of copulation and spawning. Mature females were found during 10 months and mature males during 8 months being both frequent in January and February. Reproductive activity was slightly asynchronous between sexes with males reaching maturity before females. Gonadic release occurred earlier in males between January and March against February to April in females. These findings were in agreement with field observations of copulation in January and February and egg-capsule laying in late February and March. Hatching juveniles were observed in the field in April and May.