Mugil Cephalus Research Articles

Assessment of potentially toxic metals, metalloids, and non-metals in muscle and liver tissue of Two Fish Species (Mugil cephalus Linnaeus, 1758 and Odontesthes regia (Humboldt, 1821) from the Coastal Area of Callao, Peru

The bioaccumulation of potentially toxic metals, metalloids, and non-metals in human organs, tissues, and cellular structures can lead to the emergence of related pathologies, primarily affecting the nervous system, kidneys, liver, and endocrine system. Therefore, it is necessary to assess the concentrations of potentially toxic metals and other contaminants to ensure the safe consumption of the population. To this end, this study aimed to evaluate the accumulation of potentially toxic metals, metalloids, and non-metals in the muscle and liver tissue of fish captured in the Bay of Callao, Peru. Three sampling areas (PA1: Naval School; PA2: Peruvian Marine Institute; PA3: Callao Pier) were considered, where two fish species (Mugil cephalus and Odontesthes regia) were collected to determine the degree of inorganic contamination by inductively coupled plasma optical emission spectrometry. The potentially toxic metals, metalloids, and non-metals with the highest concentration values in the muscle of M. cephalus were K>P > Ca>Mg>Fe>Zn>Al, while in the liver, the highest concentrations were K>Mg>P > Ca>Fe>Zn>Cu. M. cephalus specimens collected in PA1 exhibited high As concentrations, while those from PA3 had high Pb and Se concentrations. For O. regia, values in the muscle tissue were K>P > Ca>Mg>Fe>Zn>Sr, while in the liver, the highest concentrations were K>P > Mg>Ca>Fe>Zn>Al>Sr. As, Pb, and Se values in PA1 were higher than those observed in other sampling points. Some significant correlations were observed between pairs of metals, metalloids, and non-metals in the tissues of both fish species. As, Cd, Pb, Cr, and Se exceed international standards in both muscle and liver tissues of both species, representing a potential risk to human health and the aquatic ecosystem.

Cross-sectional analysis of risk factors associated with Mugil cephalus in retail fish markets concerning methicillin-resistant Staphylococcus aureus and Aeromonas hydrophila.

Aeromonas hydrophila and methicillin-resistant Staphylococcus aureus (MRSA) are potent bacterial pathogens posing major hazards to human health via consuming fish harboring these pathogens or by cross-contamination beyond the contaminated environment. The aim of this study was to determine risk variables associated with the presence of certain pathogenic bacteria from Mugil cephalus fish in retail markets in Egypt. The virulence genes of A. hydrophila and S. aureus were also studied. Furthermore, the antibiotic sensitivity and multidrug resistance of the microorganisms were evaluated. In a cross-sectional investigation, 370 samples were collected from mullet skin and muscle samples, washing water, fish handlers, knives, and chopping boards. Furthermore, fish handlers' public health implications were assessed via their response to a descriptive questionnaire. S. aureus and Aeromonas species dominated the investigated samples with percentages of 26.76% and 30.81%, respectively. Furthermore, A. hydrophila and MRSA were the predominant recovered bacterial pathogens among washing water and knives (53.85% and 46.66%, respectively). The virulence markers aerA and hlyA were found in 90.7% and 46.5% of A. hydrophila isolates, respectively. Moreover, the virulence genes nuc and mec were prevalent in 80% and 60% of S. aureus isolates, respectively. Antimicrobial susceptibility results revealed that all A. hydrophila isolates were resistant to amoxicillin and all MRSA isolates were resistant to amoxicillin and ampicillin. Remarkably, multiple drug resistance (MDR) patterns were detected in high proportions in A. hydrophila (88.37%) and MRSA (100%) isolates. The prevalence of Aeromonas spp. and S. aureus had a positive significant correlation with the frequency of handwashing and use of sanitizer in cleaning of instruments. MRSA showed the highest significant prevalence rate in the oldest age category. The pathogenic bacteria recovered in this study were virulent and had a significant correlation with risk factors associated with improper fish handling. Furthermore, a high frequency of MDR was detected in these pathogenic bacteria, posing a significant risk to food safety and public health.

The effect of heavy metals mobility on their bioavailability in Güllük Lagoon, Aegean Sea

The mobility and bioavailability of heavy metals (HMs) were investigated in the Güllük Lagoon, the southern part of the Aegean Sea. Total concentrations and chemical fraction concentrations of Cd, Pb, Cu, Fe, Mn, Zn and Hg in surface sediment, total concentrations of these metals in Mugil cephalus tissues (liver, gill, skin and muscle) and aquatic plant Ludwigia stolonifera were determined using atomic absorption spectrometry (AAS). The Risk Assessment Code used to evaluate the mobility and bioavailability of metals was found to be the highest for Cd, and the Geoaccumulation Index, which indicates the pollution level in the sediment, was found to be the highest for Hg. It was determined that Hg concentrations in the muscle tissue of M. cephalus were higher than the threshold values. Furthermore, the values of the chemical fraction stages and risk assessment code indicated that Cd and Hg were mobile in surface sediment and biota. Based on the results of the study, it can be argued that the anthropogenic activities in the region affect the concentrations of especially Cd, Cu, and Hg in sediment and biota. The high metal concentrations measured in the study show that the study area is under the effect of thermal power plants, domestic, industrial, and agricultural wastes brought by the Sarıçay River, and aquaculture, which is intense in the region. As a result, it is emphasized that potential sources of Hg, Cd, and Cu pollution should be determined and precautions should be taken to protect the ecosystem and public health in Güllük Lagoon in this study.

Reproductive biology of estuarine migrants Mugil cephalus from Narmada estuary, west coast of India

The reproductive biology of an estuarine migrant, Mugil cephalus, as well as the estimated length-weight relationships of the specimens obtained from the west coast of India, downstream of the Narmada estuary, were examined in the present study. From November 2018 to February 2020, gill nets, bagnets, and dragnets were used seasonally to collect fish samples from the four landing sites of Jhanor, Bharuch, Bhadbhut, and Mehegam. The studies also looked at how salinity, total alkalinity, pH, specific conductivity, depth, water temperature, transparency, dissolved oxygen, and pH affected M. cephalus reproduction. Mugil cephalus had a size range of 113–296 mm and weighed 13.2–283 g, and there were no noticeable differences between the sexes (0.97: 1.0). Males were estimated to be 158 mm in length and females were estimated to be 171 mm in length at first maturity. Throughout the seasons’, spawning activity has been seen, with a peak in winter months (January and February). The spawning season, which occurs in the months of January and February, was when highly gonado-somatic (GSI) values were observed. Mugil cephalus was found to be a high-fecund species, with absolute fecundity, ranging from 18525–567688 (184706 ± 159527, mean ± SD) and relative fecundity from 207–2117 (1012 ± 582, mean ± SD). Variations of GSI values for females’ individuals indicated that the highest values were observed during January 2019 (18.31 ± 8.50, mean ± SE) and February 2020 (10.63 ± 2.97, mean ± SE) indicating peak spawning seasons of M. cephalus during those months. The distribution of ova diameter frequency indicates that the species spawns at least twice a year in batches. The current findings will improve our understanding of the biology of M. cephalus, an estuary migratory species, which will be useful in the subsequent management of similar migratory species in estuarine environments.

Parasaturnius maurepasi n. gen. et n. comb. (Digena: Bunocotylidae) from the stomach of the silver mullet, Mugil curema (Perciformes: Mugilidae) in coastal lagoons of northern Yucatán, Mexico

Bunocotylid trematodes represent a group of 149 species with a rather complex taxonomic history. The current concept of the subfamily only includes three genera, Bunocotyle, Saturnius, and Robinia. Specimens of a bunocotylid were collected from the silver mullet, M. curema, from a coastal lagoon of Yucatán and identified as belonging to Saturnius. Further detailed morphological study revealed they corresponded to S. maurepasi, a species previously reported from the stripped mullet, Mugil cephalus in Mississippi, USA. Specimens were sequenced for the LSU of nuclear ribosomal RNA gene (28S) to test their phylogenetic position. We discovered that they do not belong in Saturnius since they nest as an independent lineage which is the sister taxa of a clade formed by Robinia, and Saturnius + Bunocotyle; additionally, the new genus exhibits high genetic divergence (10-12%) with respect to species allocated in the other bunocotylid genera. The species S. maurepasi was then transferred to the new genus as Parasaturnius maurepasin. gen., n. comb. that was created to accommodate it, and was redescribed based on newly sampled specimens.

Effect of cryopreservation on motility, DNA integrity and gene expression in grey mullet, Mugil cephalus sperm

This study documents the effect of cryopreservation on motility, DNA integrity, and gene expression in Mugil cephalus sperm. Fresh sperm were cryopreserved using V2 extender (V2E) or 0.3 M glucose, each in combination with one of three cryoprotective agents (CPAs), i.e., 10 % of dimethylsulfoxide, ethylene glycol, or glycerol, all at once. After two different storage (7- vs 60- day) periods in liquid nitrogen, sperm samples were thawed. Single-cell gel electrophoresis was used to detect the DNA integrity. Heat shock proteins (HSPs), HSP70, HSP90 and glutathione peroxidase (GPx2) genes mRNA expression levels was documented using qRT-PCR. The results demonstrated that among 0.3 M glucose + CPAs combinations, EG recorded higher frozen-thawed motility 69 % (7- day) and 59 % (60- day). Similarly, in V2E + CPAs combinations, EG recorded higher frozen-thawed motility 31 % (7- day) and 26 % (60- day). The DNA integrity of all thawed sperm (both periods) did not differ from that of fresh sperm. The qRT-PCR results revealed that in the combination of 0.3 M glucose + CPAs, the level of HSP90 and GPx2 gene expression was found to be upregulated in frozen-thawed sperm on both periods. Whereas, the expression level of the HSP70 gene was down-regulated. On the contrary, in the combination of V2E + CPAs, the expression levels of HSP70, HSP90 and GPx2 genes could not be detected on both periods. Overall, the findings of this study demonstrate that the cryomedium (extender + cryoprotectant) has a more influential role in the motility and levels of gene expression in the frozen-thawed sperm of M. cephalus.

Impact of some heavy metal accumulation in different organs on fish quality from Bardawil Lake and human health risks assessment

Bardawil Lake is a unique aquatic ecosystem that provides a habitat for various fish and other marine organisms. This study aimed to analyze the quality of fish species to prove that this lake is free of pollution, not other Egyptian lakes, due to the accumulation of some heavy metals (Cd, Pb, Cu, and Zn) in various tissues of fish species that were caught from this lake. Thirty-five fish samples were caught during the Spring of 2018 from seven different species: Mugil cephalus, Liza auratus, Sparus aurata, Dicentrarchus labrax, Siganus rivulatus, Anguilla angilla, and Solae solea. The Association of Official Analytical Chemists methods using a spectrophotometer determined the biochemical composition. In contrast, atomic absorption spectrometry (AAS) was employed to determine the heavy metals expressed by µg/g wet weight. Results exposed that the accumulation of essential micronutrient (Cu, Zn) content was higher than toxic elements (Cd & Pb) in muscles in order to Zn > Cu > Pb > Cd. Muscles < gills < liver in order of all metals except Pb with order muscles < liver < gills. The metals studied in the muscles were lower than those set by the WHO and the EU standards. The carcinogenic risk with lower allowable limits of 1 × 10–6 to 1 × 10–4 in both normal and high consumption groups; target and total target hazard quotients (THQ & HI) in muscles were < 1. The biochemical composition level was highest in the liver, except for protein, which was highest in muscle for all fish species. There is no evidence of harmful contaminants in the muscular tissue of the fish sampled from Bardawil Lake, although fishing activity. However, customers should know that health concerns may be associated with overeating fish.

The yellow mullet fish oil from the Banc d’Arguin Imrâguens in Mauritania: an example of polyunsaturated fatty acids transfer from diatoms to the fish within the alimentary chain

The Banc d’Arguin National Park (PNBA) in Mauritania is listed by the UNESCO World Heritage. It is characterized by an exceptionnal marine biodiversity with numerous endemic species and it provides a major site of reproduction for western Africa fish. The Imrâguens form fisherman communities established at Banc d’Arguin, who live upon fishing the yellow mullet (Mugil cephalus) during its migration and derived products. The fish oil produced by Imrâguens from mullet heads is rich in omega 3 polyunsaturated fatty acids (37.7 % of total fatty acids). The main fatty acid is eicosapentaenoic fatty acid (EPA ; 20.18 ± 0.01 %). This fatty acid is particularly abundant in diatoms, that contribute to 20- 30% of mullet feeding. The identification of 16:4n-1 also provide a good trophic marker for yellow mullet feeding on diatoms. The lipases potentially involved in the mobilization of these fatty acids in the course of digestion of diatoms were identified from the analysis of Mugil cephalus genome. Genes encoding a lipase homologous to gastric lipase and four lipases homologous to pancreatic carboxylester hydrolase or bile-salt stimulated lipase were identified. These later could be involved in the lipolysis of galactolipids, the main lipids present in diatom photosynthetic membranes which are rich in EPA. These data provide an added value to the traditional fishing practice of Imrâgens and highlight the nutritional value of the fish oil they produce.

Comparative Gene Expression Level of Reproductive Genes Along the Brain-Pituitary-Gonad Axis in the Ripe Female of the Wild and Captive Grey Mullets; Mugil cephalus

Comparative Gene Expression Level of Reproductive Genes Along the Brain-Pituitary-Gonad Axis in the Ripe Female of the Wild and Captive Grey Mullets; Mugil cephalus

Description and pathology of a new genus and species of fish blood fluke (Digenea: Aporocotylidae Odhner, 1912) infecting white mullet, Mugil curema Valenciennes, 1836 (Mugiliformes: Mugilidae) in Mobile Bay (northern Gulf of Mexico) with a phylogenetic analysis.

Three fish blood flukes (Aporocotylidae Odhner, 1912) infect mullets (Mugiliformes: Mugilidae): Cardicola mugilis Yamaguti, 1970 and Plethorchis acanthus Martin, 1975 infect striped mullet, Mugil cephalus Linnaeus, 1758 in the Central Pacific Ocean (Hawaiian Islands) and Brisbane River (Australia), respectively; Cardicola brasiliensis Knoff & Amato, 1992 infects Lebranche mullet, Mugil liza Valenciennes, 1836 from the Southwestern Atlantic Ocean (Brazil). White mullets were cast-netted from the mouth of Deer River, a coastal saltmarsh of Mobile Bay, in the north-central Gulf of Mexico and examined for blood fluke infections. Specimens of Mugilitrema labowskiae Warren & Bullard n. gen., n. sp. were found infecting the endocardial surface and inter-trabecular spaces of the atrium, ventricle, and bulbous arteriosus. The new genus and species differ from all other aporocotylids by having the combination of two post-caecal testes, a uterus with straight ascending and descending portions, and a common genital pore. The 28S analysis recovered the new species and P.acanthus as sister taxa and Aporocotylidae as monophyletic. Carditis associated with intense infections comprised endocardial hyperplasia, resulting in a thickened cardiac endothelium. Probable dead or deteriorating eggs in the myocardium were encapsulated by granulomas composed of epithelioid histiocytes. Live eggs infected the afferent artery of gill filaments and were associated with varied hyperplasia of the overlying epithelium and haemorrhaging from the afferent artery in high-intensity infections. The new species is the first aporocotylid infecting a mullet from the northwestern Atlantic Ocean and only the second description of demonstrable endocarditis attributed to an adult fish blood fluke infection.

Contaminación por microplásticos en Cynoscion spp, Opisthonema libertate y Mugil cephalus del Pacífico Oriental Tropical

Microplastics create serious problems in the seas, threatening marine life, polluting water and affecting ecosystems. Its accumulation and consumption by marine organisms has negative consequences throughout the food chain. Based on this, the present work evaluated the contamination by microplastics in Cynoscionspp, Opisthonema libertate and Mugil cephalus, species of high and low depth of the Eastern Tropical Pacific in Ecuador. Among the results obtained, the presence of shapes and colors of plastic polymers in M. cephaluscaptured at a shallow depth of up to 1.8 meters stands out. The presence of 449 units of plastic polymers was detected out of a total of 36 samples of M. cephalus, which represents an occurrence of 83%. In contrast, the lowest occurrence was 0% for Cynoscion sppand 6% for O. libertate, in deep drafts up to 9.1 meters deep. In shallow-draft species, the presence of microplastics may be related to their greater proximity to sources of pollution, such as urbanized coastal areas or intensive human activities. However, the absence of microplasticsin deep-water species may indicate lower exposure or more efficient filtering capacity.

Sustainable Aquafeed with Marine Periphyton to Reduce Production Costs of Grey Mullet, Mugil cephalus

Sustainable Aquafeed with Marine Periphyton to Reduce Production Costs of Grey Mullet, Mugil cephalus

Barcoding Mullets (Mugilidae): Genetic Characterization of Exploited Species in Southern Peninsular India

Fishes of the Mugilidae family are poorly known from a taxonomic perspective, largely because of their conservative morphology. In this paper, we aim to fill the knowledge gap and data deficiency regarding the genetic diversity of mullets occurring in southern peninsular India. A comprehensive mitochondrial phylogeny based on 238 COI sequences (78 newly generated) and three species delimitation methods (ASAP, RESL, and ABGD) confirmed the presence of 21 species of mullets within eight genera in southern peninsular India. These include one species each under the genera Rhinomugil Gill 1863, Minimugil Durand, Chen, Shen, Fu, and Borsa, 2012, Plicomugil Schultz 1953, and Ellochelon Whitley 1930; seven species of Planiliza Whitley 1945; four species of Crenimugil Schultz 1946; four species of Osteomugil Luther 1982; and two species of the “Mugil cephalus Linnaeus 1758” complex—though with uncertainty regarding the exact geographic origin of one of the two species of the “Mugil cephalus” complex and one species phylogenetically close to Planiliza subviridis (Valenciennes 1836). We provide an overview of the specific geographical regions in southern peninsular India, and “species groups”, which require future research using an integrative approach, so as to unravel the true extent of mullet diversity and their distribution in the region.

A new sex-specific genetic marker (fshr 1834G>T) for flathead grey mullet, Mugil cephalus, in Queensland, Australia

In this study, genetic sex marker candidates from northern hemisphere Mugil cephalus were tested to see if they could be used to sex a population originating from south-east Queensland, Australia. As such, a region of the follicle stimulating hormone receptor (fshr) gene was sequenced but did not contain previously published single nucleotide polymorphisms (SNPs). However, further screening of the sequenced fshr region revealed a promising sex marker candidate for Queensland M. cephalus, fshr 1834 G>T, which was accurate in 100% of fish tested (excluding intersex fish, which had the female genotype). While all females tested were homozygous G/G, males presented as either G/T (common) or T/T (lower frequency). Subsequently, a real-time high-resolution melt was developed to facilitate rapid and accurate genotyping of M. cephalus based on the fshr 1834 G>T SNP. Initial results suggest that fshr 1834 G>T is a useful SNP that can reduce the need for more invasive sampling techniques such as gonadal biopsy, provide information relating to the sex of captive stock prior to gonadal maturation, and may prove useful in wild population surveys and stock assessment.

Green Extraction and Preliminary Biological Activity of Hydrolyzed Collagen Peptides (HCPs) Obtained from Whole Undersized Unwanted Catches (Mugil cephalus L.).

Considering the global increase in fish consumption, the growing side-streams coming from the fish supply chain (e.g., skin, fins, tail, heads…), also including undersized or "unwanted catches", have been recently proposed as source of high-value bioactive compounds (e.g., peptides and fatty acids). In this case study, hydrolyzed collagen peptides (HCPs) were extracted from different parts of Mugil cephalus L. using environmentally friendly techniques such as ultrasounds and enzymatic treatments. Both a mixed biomass derived from the skin, fins, and tail, and a whole fish, were considered as starting biomass, simulating the unsorted processing side-streams and an undersized/unwanted catch, respectively. The extracted HCPs were purified in fractions (<3 KDa and >3 KDa) whose yields (about 5% and 0.04-0.3%, respectively) demonstrated the efficiency of the hydrolysis process. The extraction protocol proposed allowed us to also isolate the intermediate products, namely the lipids (about 8-10%) and the non-collagenous proteins (NCs, 16-23%), whose exploitation could be considered. Each sample was characterized using Sircol, UltraViolet-Spectra, and hydroxyproline assay, and the viability of their collagen fractions was tested on human endothelial cells. Significant effects were obtained at a fraction of <3 KDa, in particular at a concentration of 0.13 µg/mL. The T-scratch test was also performed, with positive results in all fractions tested.

Microbiome study of a coupled aquaponic system: unveiling the independency of bacterial communities and their beneficial influences among different compartments

To understand the microbiome composition and interplay among bacterial communities in different compartments of a coupled freshwater aquaponics system growing flathead grey mullet (Mugil cephalus) and lettuces (Lactuca sativa), 16S rRNA gene amplicon sequencing of the V3–V4 region was analysed from each compartment (fish intestine, water from the sedimentation tank, bioballs from the biological filter, water and biofilm from the hydroponic unit, and lettuce roots). The bacterial communities of each sample group showed a stable diversity during all the trial, except for the fish gut microbiota, which displayed lower alpha diversity values. Regarding beta diversity, the structure of bacterial communities belonging to the biofilm adhering to the hydroponic tank walls, bioballs, and lettuce roots resembled each other (weighted and unweighted UniFrac distances), while bacteria from water samples also clustered together. However, both of the above-mentioned bacterial communities did not resemble those of fish gut. We found a low or almost null number of shared Amplicon Sequence Variants (ASVs) among sampled groups which indicated that each compartment worked as an independent microbiome. Regarding fish health and food safety, the microbiome profile did not reveal neither fish pathogens nor bacterial species potentially pathogenic for food health, highlighting the safety of this sustainable food production system.

LENGTH-WEIGHT RELATIONSHIP OF EIGHT SPECIES OF FISH CAUGHT BY TRADITIONAL PAPUAN FISHERS IN YOUTEFA BAY, INDONESIA

In this study, data on length and weight of fish were used to determine the length-weight relationship and condition factors of eight fish species that are targeted by traditional Papuan fishers and have high economic value (Lutjanus fulvus, Gerres oyena, Parupeneus barberinus, Siganus spinus, Siganus canaliculatus, Pelates quadrilineatus. Mugil cephalus, and Hemiramphus far) in Youtefa Bay, Papua Province, Indonesia. A total of 245 fish specimens were collected from Papuan fishermen during the period January to March 2020. The total length and body-weight of the fish specimens studied ranged from 15.2 to 32.1 cm (average 20.26±3.73 cm) and 42.72 to 371.86 g (average 124.10±52.45 g), respectively. The b value ​​for all fish species studied ranged from 2.6919 to 3.0791, with the coefficient of determination (R2) ranging from 0.9022 to 0.9947. The growth patterns of the eight fish species were allometric (b ≠ 3; t-test &lt; t-tab), where L. fulvus (2.824), P. barberinus (2.9136), S. canaliculatus (2.989), P. quadrilineatus (2.9577), M. cephalus (2.9096), and H. far (2.6919) were negative allometric (b &lt; 3), while G. oyena (3.0596) and S. spinus (3.0791) are positive allometric (b &gt; 3). Meanwhile, the relative condition factor and Fulton condition factor values ​​ranged from 0.874 to 1.201 (average 0.999±0.321) and 0.204 to 2.726 (average 1.612±0.515). M. cephalus had a higher relative condition factor, while L. fulvus had a higher Fulton condition factor than other fish species

A REVIEW OF FISH DIVERSITY AND MANAGEMENT OF THE VJOSA BASIN: THE FIRST FREE FLOW RIVER PROTECTED AREA IN THE BALKANS

Vjosa River, an ecologically important area and the last Europe free-flowing river, is an essential aquatic ecosystem for the Albanian ecological, social, and cultural aspects. Fish and other aquatic species are notable among livings composition found in this region. The river environment is unfortunately seriously threatened by the excessive use of its resources, and hence, the goal of this study was to examine the status of fish biodiversity and the demands of the ecosystem for management. The Vjosa river is home of at least 34 species of fishes inhabiting the river and delta system, of which 29 are native, including eight species endemic to the Balkans. With 12 species, Cyprinidae is by far the most specious family, followed by Mugilidae (five). Salmonidae and Acipenseridae are represented by 2 species each. The remaining ten families are represented by a single species. At least four species (Pseudorasbora parva, Oncorhynchus mykiss, Carassius spp., Gambusia holbrooki) were introduced into the Vjosa basin. The lower river reach is populated by other species as European eel (Anguilla anguilla), species of Family Mugilidae (Mugil cephalus, Liza ramada, Liza salienes, and Chelon labrosus), Seabream (Sparus aurata), Seabass (Dicentrarchus labrax), Flatfish (Platichthys flesus, common sole (Solea spp.), etc., while the resident species associated with saline water include numerically prevalent with the two species Atherina boyeri and Aphanius fasciatus showing presence and significance.

Position of Polyclithrum within Gyrodactylidae (Monogenoidea): incongruences between morphological and molecular phylogenies.

This study aimed to enhance our understanding in monogenoid evolution by using morphological and molecular data to determine kinship relationships between species and changes in morphological structures over time. We focused on variations in characteristics among the organisms of the family Gyrodactylidae, concentrating on the phylogenetic position of Polyclithrum with other genera in the family. We collected specimens of Polyclithrum from the striped mullet, Mugil cephalus and Swingleus, and Fundulotrema specimens from mummichog Fundulus heteroclitus in estuarine systems of South Carolina, United States. In addition, we analyzed them and other genera (including e.g., Mormyrogyrodactylus, Gyrodactyloides, and Macrogyrodactylus) using both morphological and molecular (18S rDNA) approaches. We performed phylogenetic trees based on Maximum Parsymony, Maximum Likelihood and Bayesian Inference, and constructed a character morphological matrix by Parsimony Reconstruction of Ancestral Character States method. Our results suggest a homoplastic origin with evolutionary convergences in characters, revealing that there is inconsistency between our data and previously published works based solely on morphological structures of the group. The homoplasy scenario found in Gyrodactylidae can be a result of the limited set of putative homologous morphological features. However, differences between the phylogenies based on morphology and those based on molecular data may arise from both databases. While morphology remains essential in understanding the evolution of this group, molecular data, otherwise, provide a less biased source of information for constructing phylogenetic hypotheses. Combining these data facilitates a better comprehension of the homologous status of morphological features and to understand Gyrodactylidae evolutionary history.

Distribution and Abundance of Fry and Juveniles of A Few Cultivable Fishes in and Around Cochin Backwater, Kerala, India

The investigation was carried out at four selected stations in Cochin Backwater and intertidal water of the sea representing different ecological conditions at fortnightly intervals from February to September 1989. As per the observations, among the five species of fry recorded, the grey mullet Liza parsia was dominating throughout the study period with maximum abundance during the south-west monsoon. The fry of the milk fish Chanos chanos and the Indian tarpon Megalops cyprinoides were noted only during the pre-monsoon months when the salinity and temperature of water were considerably high, whereas the fry of the grey mullet Mugil cephalus were recorded during lower temperature and salinity conditions from June to August. Among the environmental parameters, salinity, temperature and distribution of phyto- and zooplankton were found to have profound influence on the distribution of different species directly or indirectly. Hydrogen ion concentration and dissolved oxygen were not found to influence the distribution. Among the eight species of juveniles recorded during the study, those of L. parsia were dominating followed by L. macrolepis. The juveniles of C. chanos, M. cyprinoides and Valamugil cunnesius were observed only after the onset of the monsoon indicating their preference of low salinity and temperature, and higher concentration of food materials.