Some Digenetic Trematodes of Marine Fishes from the Barrier Reef and Reef Lagoon of Belize

A total of 200 marine fishes (36 species) from the Caribbean Sea off Belize were examined for digenetic trematodes and 163 (81.5%) harbored at least one species. Five species are described as new: Lasiotocus asymmetricus (Monorchiidae) from Haemulon flavolineatum; Stephanostomum belizense (Acanthocolpidae) from Caranx bartholomaei; Neolepidapedon belizense (Lepocreadiidae) from Sphyraena barracuda; Opecoeloides belizensis (Opecoelidae) from Priacanthus arenatus; Saturnius belizensis (Hemiuridae) from Mugil curema. 72 previously known species were identified, and all represent new geographical distribution records while many are recorded from new hosts. Their zoogeographical affinities are very strongly with the tropical western Atlantic, although some also occur in the eastern Atlantic, Mediterranean, and Indo-Pacific regions.     

Abundance/host size relationship in a fish trematode community.

The abundance of six species of trematodes: Aphanurus stossichi, Bacciger israelensis, Diphterostomum israelense, Plagioporus idoneus, Leprocreadium album and L. pegorchis, parasitic in the digestive tract of marine teleostei (Sparidae) collected near Jounieh (east Mediterranean), was analysed as a function of the host-size. In two parasite/host systems, infections were observed from the lowest size classes of the sample, with a clear tendency to an increase of abundance in older fish. In four others, parasites appear only above a rather high threshold class, young individuals never being infected. In the last three parasite/host systems, host invasion may occur early or late, but infection decreases above a well defined size class, old fishes rarely or never being infected. A given trematode species, when parasitizing several host species, shows similar abundance/host size relationships, e.g., P. idoneus in Diplodus vulgaris and Oblada melanura. When more than one species of trematode infects a single host species, curves can be markedly distinct; for instance, L. pegorchis was collected from Pagellus erythrinus below 15 cm. whereas D. israelense parasitized the same fish approximately above the same size. There is no evidence that such a replacement of one trematode by another in the course of host growth is a result of inter-specific competition.     

Redescriptions of two frequently recorded but poorly known hemiurid digeneans, Lecithochirium musculus (Looss, 1907) (Lecithochiriinae) and Ectenurus lepidus Looss, 1907 (Dinurinae), based on material from the western Mediterranean

Two frequently reported but poorly known hemiurid digeneans, Lecithochirium musculus (Looss, 1907) (Lecithochiriinae), from the stomach of Trachinus draco and Citharus linguatula, and Ectenurus lepidus Looss, 1907 (Dinurinae), from the stomach of Spicara maena, are redescribed based on material from off the Barcelona coast of the western Mediterranean. The two species are commented upon, and Lecithochirium israelense Fischthal, 1980 is considered a synonym of L. musculus. Records of the two species in the Mediterranean Basin and North East Atlantic region are summarised.     

Unexpected large numbers of Mullus suvmuletus juveniles in open waters of the Mediterranean sampled with light attraction devices

Experimental night hauls with a purse-seine were performed using two light devices in waters off Majorca in the western Mediterranean to investigate light attraction of juvenile fishes in epipelagic waters over the continental slope. Large numbers of Mullus surmuletus were caught indicating that light devices are suitable for sampling juveniles (2–6 cm) of this species. The data obtained can be used to provide valuable information on geographic distribution and spatial aggregation patterns of this mullid, altogether with the acquisition of biological samples for growth or stomach contents analyses of juveniles stages.     

Allometric Growth in Four Species of Digenetic Trematodes of Marine Fishes from Belize

Four species of digenetic trematodes of marine fishes from Belize are studied for allometric growth: Multitestis rotundus Sparks, 1954 (Lepocreadiidae), Stenopera equilata Manter, 1933 (Opecoelidae), Leurodera decora Linton, 1910 (Hemiuridae), Prosorhynchus pacificus Manter, 1940 (Bucephalidae). These are compared with six other species for which allometric growth is known. Positive growth is exhibited in all species only by the hindbody, whereas the forebody, suckers, and pharynx are negative in all. The body width, post-testicular body, and gonads are positive in some species and negative in others. At times the body proportion or organ is growing at about the same rate as the body length.     

Habitat related differences in lipid reserves of some exploited fish species in the north‐western Mediterranean continental shelf

At a large‐scale, the lipid content in the muscle of Pagellus acarne and Pagellus erythrinus was higher in the Gulf of Lions than in the Catalan Sea. Furthermore, there was a significant effect of depth on lipid content of Mullus barbatus, Mullus surmuletus and P. acarne , fishes with the highest lipid levels inhabiting the shallowest parts of the Gulf of Lions (all three species) and the Catalan Sea (last two species). At a small‐scale, the study revealed differences in the condition of Diplodus sargus sargus between protected (Natural Park of Cap de Creus) and the unprotected habitats. Total lipid content in the muscle of D. s. sargus during spawning was higher within the protected area than in adjacent unprotected rocky areas. Because lipids play a critical role in the health, growth and reproduction of fishes, results from this study support the relative importance of some habitats (shallow v . deeper parts of the continental shelf, the Gulf of Lions v . the Catalan Sea, and the protected bottom areas of the Natural Park of Cap de Creus v . the unprotected bottom areas) for the productivity of different Mediterranean fishes.     

Genetic structure of three marine fishes from the Gulf of Pagasitikos (Greece) based on allozymes, RAPD, and mtDNA RFLP markers

In the present work we used three molecular techniques (allozymes, RAPDs and mtDNA RFLPs) in order to study the genetic structure of three commercial marine species (Mullus surmuletus, Mullus barbatus, and Pagellus erythrinus). Each species was sampled from three locations within the Gulf of Pagasitikos, Greece and from two neighbouring locations outside the Gulf (Trikeri and Alonissos). Values of genetic heterozygosity and nucleotide diversity for all populations studied were similar or above the mean values observed in marine fishes. None of the three types of molecular markers used revealed diagnostic patterns, which could allow the allocation of individuals to one of the populations. The analyses revealed that the three populations within Pagasitikos were homogenous representing thus a panmictic stock. However, there were evidences of genetic population subdivision between localities from inside and outside of the Pagasitikos Gulf. The results provide essential information for the design of a sustainable management plan of the Gulf of Pagasitikos and its demersal fish resources.     

Niche separation between colonizing and indigenous goatfish (Mullidae) along the Mediterranean coast of Israel

The present study assesses the resource partitioning between two Red Sea colonizers, the goldband goatfish Upeneus moluccensis and the brownband goatfish U. pori , and the two indigenous Mediterranean goatfishes, the red mullet Mullus barbatus and the striped mullet M. surmuletus , along the Mediterranean coast of Israel.
Niche separation was studied along three axes: habitat selection, feeding habits and spawning season. Habitat selection is the most significant parameter separating the species. The two colonizing species occupy a shallow habitat, U. pori dominating the primarily sandy bottom at 20–30 m and U. moluccensis at 40–50 m, at which depth the sea bottom becomes increasingly silty. Of the two indigenous species, M. barbatus is dominant in depths below 55 m, while M. surmuletus appears at low abundance in all depths.
Niche separation by feeding habits is much less evident. All four species feed primarily on macrurid crustaceans and thus the values of diet overlap are rather high (0·666≤ T ≤0·928). Prey size is not an important factor in niche separation. Young fishes (S.L>,115 mm) of all four species feed upon prey of similar size (20–160 mg). Among older individuals (S.L.>115 mm) three species continue to feed upon the same size prey, while U. moluccensis feeds upon considerably larger prey (600–2200 mg).
The difference between the spawning seasons of the colonizing vs indigenous species and consequent timing of benthic settling may contribute to niche separation.
The results of this study suggest that success in colonization by Red Sea goatfish may be due to the existence of unexploited niches in the eastern Mediterranean ecosystem.     

The occurrence of two opecoeliid digeneans in Mullus barbatus and M. surmuletus from the Spanish south-eastern Mediterranean

The infection by Opecoeloides furcatus and Poracanthium furcatum (Opecoeliidae) was studied in 121 Mullus barbatus and 113 M. surmuletus collected from the Spanish south-eastern Mediterranean. The prevalence of infection was most frequent in M. surmuletus with values of 81.42% for O. furcatus and 38.05% for P. furcatum. In M. barbatus the prevalences of O. furcatus and P. furcatum were 54.54% and 14.88% respectively. Statistically significant differences were found between the infection of the two hosts with P. furcatum. No significant differences in worm burdens could be attributable to host size or to seasonal changes, although a lower infection of M. barbatus by O. furcatus occurred in the autumn. Furthermore, the electrophoretic mobility of the enzyme malic dehydrogenase (MDH) was also studied and both digeneans presented different patterns, corresponding in both cases to homozygotic genotypes.     

Opecoelidae (Digenea) from western Mediterranean fishes: three rare species

Three little-known opecoelid digeneans from marine fishes off Corsica, France, are redescribed and their relationships discussed. Plagioporus novella Maillard & Lambert, 1978 from Conger conger is transferred to Podocotyle as P. novella (Maillard & Lambert, 1978) n. comb. The new combinations Podocotyle tohei (Yamaguti, 1970) and P. congeri (Yamaguti, 1970) are formed for species originally assigned to Plagioporus. Podocotyle temensis Fischthal & Thomas, 1970 from Epinephelus guaza is redescribed and compared with the other Podocotyle species reported from the Mediterranean. A third species, Pseudopecoeloides chloroscombri (Fischthal & Thomas, 1970) n. comb. (was Podocotyloides), is redescribed from three Trachurus species and a key to the species of this Pseudopecoeloides is given.     

Taxonomic relationships between four species of the Mullidae family revealed by three genetic methods: allozymes, random amplified polymorpic DNA and mitochondrial DNA

Genetic distances were lower between Upeneus moluccensis and Pseudopeneus prayensis than between those species and Mullus barbatus and Mullus surmuletus . However, for allozymes, the two Mullus species were found genetically more distinct from U. moluccensis than from P. prayensis , but RAPD and mtDNA analysis showed the opposite. RAPDs revealed less interspecific divergence compared with allozymes and the results they produced were more consistent with mtDNA analysis. Although RAPDs did not add any supplementary taxonomic information, they proved valuable tools for quick and reliable species discrimination compared with allozymes and mtDNA.     

Exploitation patterns of the European hake Merluccius merluccius, red mullet Mullus barbatus and striped red mullet Mullus surmuletus in the western Mediterranean

The exploitation patterns of three target species ( Merluccius merluccius , L. 1758 , Mullus barbatus , L. 1758, Mullus surmuletus , L. 1758) of the western Mediterranean demersal fisheries were compared. The study was carried out in five ports along the Italian and Spanish coasts. These three species are fished simultaneously or sequentially by a number of gears, their use during the year being different depending on the area. The trawl catches dominated the landings, both in number and weight, but varied greatly during the year. The size ranges of specimens in the catches were in their major part different among the types of gear. Artisanal methods (gillnet and long line for M. merluccius , trammel net for Mullus spp.), used seasonally, contributed primarily to landings of larger, adult specimens, whereas trawl catches consisted mainly of smaller sized individuals, recently recruited to the fishery. In M. merluccius, individuals of less than 20 cm total length accounted for 80 to 95% of the annual catch in numbers, and between 15 and 60% of the catch in weight, depending on the port. This situation indicates a substantial over-exploitation and a high risk of long-term unsustainability in stock development and production.     

A new cystidicolid nematode from Mullus surmuletus (Perciformes: Mullidae) from the western Mediterranean

Ascarophis valentina n. sp. is described from Mullus surmuletus off the Valencian coast of Spain on the basis of both light and scanning electron microscopy. It can be distinguished from the other members of the genus by the length of the left (long) spicule of the males and by egg morphology. An updated grouping of the species of Ascarophis considered valid is provided with respect to these characters. The new species resembles Ascarophis capelanus, belonging to the group of species possessing eggs with a single polar knob with filaments, but is distinguished by the size of the body, the length of the esophagus (especially in relation to body length), the position of the vulva, and the size of the left spicule. The new species also shows substantial morphological differences compared with the 3 species, Ascarophis mullusi, Ascarophis upenei, and Ascarophis parupenei, previously described from mullid hosts.     

Digenean species diversity in teleost fishes from the Gulf of Gabes, Tunisia (Western Mediterranean)

This study is the first attempt to survey the diversity of fish digeneans in the Gulf of Gabes (southern coast of Tunisia). A total of 779 fishes belonging to 32 species were sampled. 53 species of Digenea belonging to 15 families were recorded. Among these species, 24 are reported for the first time from the coast of Tunisia. We report one new host record, Lecithochirium sp. from Sardinella aurita. The Hemiuridae is the dominant family. A host-parasite list is presented with the information on the prevalence, abundance and mean intensity of each species collected. The diversity of Digenea is compared with other localities in the Mediterranean Sea and the northern east of Tunisia. The Gulf of Gabes shows the lowest diversity linked to the anthropogenic activities and impact of exotic species. The use of Digenea as indicators of the state of the ecosystem is discussed.     

Difference in diet and size‐related trophic level in two sympatric fish species,the red mullets Mullus barbatus and Mullus surmuletus,in the Gulf of Lions (north‐west Mediterranean Sea)

Stable‐isotope ratios (δ¹⁵N and δ¹³C) and diet of the red mullets Mullus barbatus and Mullus surmuletus were analysed in two zones differently subjected to the Rhône River runoff in the Gulf of Lions (north‐west Mediterranean sea) in May and October 2004. δ¹⁵N and δ¹³C increased significantly with fish size in M. barbatus in both zones and seasons, whereas no significant trend was evidenced in M. surmuletus. A clear size‐related shift in diet was observed in M. barbatus, with an increase in polychaete and shrimp consumption with size and a decrease in small crustacean consumption. In M. surmuletus, a diet shift was observed only between medium and large individuals. Large M. surmuletus preyed on shrimps, polychaetes, bivalves, ophiurids and amphipods, and ingested prey of lower mean mass than M. barbatus of similar size. Difference in size‐related increase in δ¹⁵N between the two mullid fish species were related to difference of trophic level of their main prey. Sub‐surface deposit‐feeding polychaetes, carnivorous polychaetes, shrimps and brachyurans presented higher δ¹⁵N values than bivalves, small crustaceans and ophiurids. The lower δ¹³C values observed in M. barbatus compared to M. surmuletus were related to a higher consumption of sub‐surface polychaetes in the former species. Significantly, lower δ¹³C were recorded in fishes collected off the Rhône River, particularly in spring, suggesting an influence of river inputs as a source of particular organic matter for mullids in this zone after the flooding season. Thus, these closely related sympatric fish species displayed diet divergences that were reflected in their stable isotopic signatures.     

长江中游鱼类的复殖吸虫Ⅰ.鲟拟动殖吸虫(动殖科)新属、新种的描述

从1981到1983年,作者等曾多次在湖北省宜都县和黄冈县团风镇两地,从事长江中游鱼类寄生吸虫的调查研究。在70多种鱼中,获得了一批吸虫标本,将陆续整理后发表。本文首先报告在中华鲟Acipenser sinensis Gray中发现的动殖科Zoogonidae Odhner,1911一新属、新种吸虫。       

Foraging interactions among three benthic fish in a Posidonia oceanica reef lagoon along the Tyrrhenian Coast

Three benthic predators Coris julis, Symphodus cinereus and Mullus surmuletus in a Posidonia oceanica reef lagoon of the Tyrrhenian coast had a broad diet, including hard-bodied invertebrates such as crustaceans and molluscs, but revealed consistent interspecific differences. Diet overlap was greater between C. julis and M. surmuletus in comparison to other combinations. All three species were diurnal feeders, but with diVerent daily patterns of foraging based on diVerent prey availability. There was a general spatio-temporal correlation in non-foraging activity among the three species, but foraging activity was correlated only between C. julis and the other two species, but not between S. cinereus and M. surmuletus .There was heterospecific aggregation during foraging between C. julis and M. surmuletus , and possibly a scrounger–producer relationship between them. Fights between C. julis specimens related to foraging activity were common, but not between species. These results support the view that diVerences in spatio-temporal organization of activity, and interactions during foraging, can contribute to resource partitioning among syntopic populations of fish belonging to the same trophic group.     

Three Trematodes Including Two New Species from Fishes of the Karachi Coast

Three trematodes are described from three different species of Karachi coast fishes. Complexo-bursa magna sp.n., from Lates calcarifer , is characterized by its large body size, unlotxjd rounded ovary, large operculate eggs, and numerous vitelline follicles extending from the preacetabular region to the posterior end of the body. Monorchis heterorchis sp.n., from the fish Muraenesox cinereus , is also characterized by its relatively large body, median transversely elongated testes of variable shapes, ovary consisting of four distinct follicles and relatively large operculate eggs. Waretrema piscicola Srivastava, 1937 is reported here from the Karachi coast 17 years after its last report from the Philippines, in the same host ( Scato-phaugs argus ) but from a new locality.