Length–weight relationships of 17 less-studied fish species from Çanakkale, Marmara region of Turkey

This study reports length–weight relationships for 17 cryptic and rare species, Aidablennius sphynx , Arnoglossus kessleri , Callionymus pusillus , Callionymus risso , Clinitrachus argentatus , Echiichthys vipera , Gobius geniporus , Gobius paganellus , Labrus viridis , Lepadogaster lepadogaster , Ophidion barbatum , Pomatoschistus minutus , Pomatoschistus pictus , Salaria pavo , Tripterygion delaisi , Tripterygion tripteronotus and Zebrus zebrus from Çanakkale near shores in the Marmara region of Turkey.     

Weight‐length relationships for five fish species from a temperate coastal lagoon of southern Europe

The weight‐length relationships (WLR) were estimated for five fish species of Ria Formosa, a coastal lagoon in southern Portugal. WLRs for Gobius couchi, Pomatoschistus microps and Parablennius pilicornis were determined for the first time ever and for Gobius cruentatus for the first time for the southern European Atlantic coast.     

Occurrence of vertebral deformities in Gobiidae (Pisces) from the Tagus estuary

In four species of gobiid fish caught in Tagus estuary during 1996, the incidence of skeletal deformities ranged from 2 to 5%. Differences between sampling stations or between the two most abundant species Pomatoschistus minutus and Gobius niger were statistically not significant (p > 0.05). The type of deformity depended upon species. P. minutus and P. microps showed bone nodules at the inferior side of the abdominal vertebrae, whilst G. niger and G. paganellus had shortened caudal vertebrae (achondroplasia) and deformed ural plates. The possible role of pollution or other conditions in the Tagus estuary is discussed.     

The shallow water gobiid assemblage of the Venice Lagoon: abundance, seasonal variation and habitat partitioning

The gobiid assemblage of the Venice Lagoon shallow waters was investigated by means of a semi‐quantitative standardized sampling (using a small beach seine), stratified into five main types of shallow subtidal habitats and conducted on a seasonal basis during 1 year. The degree of overlap in resource utilization among six coexisting goby species was assessed, along both the time axis, by analysing the seasonal variation in abundance and reproductive status (as revealed by the gonado‐somatic index) and the habitat axis, by comparing species abundance across different habitat types and controlling for the effects of some abiotic factors. Smaller species, and especially the marbled goby Pomatoschistus marmoratus , dominated the local assemblage. Although the cycle of shallow water colonization and seasonal variation in total abundance were basically similar, species showed differences in timing of reproduction and recruitment, as well as in habitat preference. The larger species belonging to the genera Gobius and Zosterisessor tended to overlap their habitat use, being more abundant in seagrass habitats than in the unvegetated habitats, whereas the smaller species belonging to the genera Knipowitschia and Pomatoschistus avoided seagrasses, preferring in most cases mud flats and salt marsh creeks. Within these two groups of species some further slight differences in species habitat preference, relationship with abiotic factors and reproductive ecology could be detected. Results are discussed in the light of both ecological mechanisms underlying coexistence of closely related species and the current knowledge of the phylogeny of Mediterranean gobies.     

Interspecific variation of acoustic signals in Mediterranean gobies (Perciformes, Gobiidae): comparative analysis and evolutionary outlook

Sound production of 11 Mediterranean goby species, belonging to five different genera, have been comparatively analysed on the basis of the quantitative properties of the acoustic signal emitted by the male in both the reproductive and aggressive context. The results obtained showed that three groups of species can be recognized on the basis of signal similarity: the larger sized species (genus Padogobius and Gobius paganellus ) producing tonal sounds, showing high values of pulse rate and low values of duration; the larger-sized species producing grunt sounds (genus Gobius and Zosterisessor ) with low pulse rate and low duration; and the small-sized species producing grunt sounds (genus Pomatoschistus and Knipowitschia ) with low pulse rate and high duration. The comparison between these results and those found in previous studies suggests congruence between the acoustic affinities among species and that obtained by means of morphological and genetic data. Furthermore, first hypotheses on the evolution of acoustic communication and the associated mechanisms in this fish group are suggested.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 763–778.     

Genetic analysis reveals the diversity of larval Gobiidae in a temperate estuary

Using molecular tools to examine Gobiidae, the second most abundant taxon in ichthyoplankton samples in the Gulf of Riga (Baltic Sea), the sand goby Pomatoschistus minutus was the most abundant taxon (82% of all individuals analysed), the common goby Pomatoschistus microps constituted 12% and the black goby Gobius niger 6%. The spatiotemporal distribution of P. microps and G. niger indicated a preference for habitats closer to the river inlet and their abundances increased slightly towards the end of the sampling period in summer. The species composition was interpreted in the context of the prevailing habitat conditions, characterized by extremely low water transparency, low salinity, limited spread of vegetated area and dominance of sandy–muddy substrata.     

Studies on scale regeneration in the Common goby, Pomatoschistus microps (Pisces)

The longevity of original scales and the process and consequences of scale regeneration in the euryhaline Common goby, Pomatoschistus microps (Kroyer), has been studied by monthly sampling of two populations. Scale regeneration comprises four stages: formation of a new growth centre, a regenerated area in the form of a wide central irregular area lacking concentric circuli: formation of short and widely spaced circuli at the outermost region of the regenerated area: a check in regenerated scale growth on reaching the size of the original scales: and the commencement of normal growth similar to that of the surrounding original scales. Growth of regenerated scales within 30 days was not sufficient to attain the same size of the original ones. The average percentage of regenerated scales in successive months during the life span of P. microps is about 20% in immature fish and sharply increases up to about 60% of the total scales during the breeding season. The correlation between sharp increases in regenerated scales and the breeding season is also confirmed on examining scales from two other gobioid species, Gobius paganellus and Gobius cobitis. It is suggested that the loss of a large number of scales may result in the check in body growth during the breeding season.     

Einnischung von fünf Grundeln (Teleostei, Gobiidae) der Ostsee und ihre Deutung mit Hilfe der Präadaptationstheorie

Niche occupation by 5 goby species (Teleostei, Gobiidae) in the Baltic Sea and its interpretation by means of the theory of pre-adaptation The habitats and prey of five goby species were investigated near the shore of the Lübeck Bight (SW Baltic) during the period 1989–1991. Observations showed that Gobius niger is a macrobenthos feeder, Pomatoschistus microps a meiobenthos feeder; Pomatoschistus pictus prefers meiobenthos as well as plankton while Pomatoschistus minutus feeds on benthos of every size, as well as planktonic cope-pods when offered in surplus; Gobiusculus flavescens is generally a plankton feeder but, when this component is in short supply in the summer, changes to macrobenthos. P. pictus and P. microps existed at different depths; G. flavescens and P. minutus presented countercurrent densities in shallow habitats during the course of a year. This adaptability of behaviour in habitat and prey choice can be explained by the modification ability of pre-adaptional genes in the goby genomes. After having invaded species-poor habitats such as the brackish Baltic Sea, wide niche dimensions are initially occupied. The niche is here considered to be an attribute of the species as well as of the habitat according to GÜNTHER (1950). Hence, innidation is defined as a process which implies specialization by loss of most preadaptations and leads to the optimal use of the ecosystem by the species. This process of a single species corresponds to the maturation of successions of whole biocoenoses.     

Gobius xoriguer,a new offshore Mediterranean goby (Gobiidae), and phylogenetic relationships within the genus Gobius

Ichthyological Research - Gobius xoriguer sp. nov., a new ofshore species of goby (Teleostei: Gobiidae: Gobiinae) is described based on three specimens collected in 2010, 2012 and 2018 in the...     

Composition, structure and distribution of the ichthyoplankton in a Mediterranean coastal lagoon

The species composition and assemblage structure of the ichthyoplankton from the Mar Menor Lagoon in south‐east Spain are given. The fish larvae were sorted from zooplankton samples collected at 20 stations with a plankton net (50 cm mouth diameter and 500 μm mesh) during 36 surveys between February and December 1997. A total of 39 575 fish larvae representing 14 families, 22 genera and 36 species were identified. Gobiidae was the most dominant family (77·0%) followed by Blenniidae (19·4%) and Atherinidae (1·3%). The most abundant species were Gobius niger and Gobius paganellus , which accounted for 42·7 and 19·3% of the total respectively. These species were followed in order of relative abundance by Pomatoschistus marmoratus (13·9%), Parablennius pilicornis (9·4%), Lipophrys pavo (7·7%), Atherina boyeri (1·3%) and Parablennius tentacularis (1·3%). The high species diversity (2·0–2·8 bits individual⁻¹ for the annual diversity spectra at each sampling station) reflected a diverse assemblage of species. The main commercial species in the lagoon (Sparidae and Mugilidae) were poorly represented among the ichthyoplankton and they probably enter the lagoon on the bottom as recruits. Chlorophyll a concentration in the water column was the main factor explaining the seasonal variation in larval abundance. Spatial distribution of larvae was related to hydrographical circulation patterns in the lagoon and the movement of marine‐spawned larvae through the channels connecting the lagoon with the Mediterranean Sea.     

A new species of Pomatoschistus (Teleostei,Gobiidae): the Mediterranean's smallest marine fish

The new sand goby species Pomatoschistus nanus (Teleostei: Gobiidae) is described from the northern coast of the Levantine Sea (eastern Mediterranean Sea) based on both morphological and DNA barcoding data. The new species is the smallest fish in the Mediterranean Sea and may be distinguished from congeners by the following features: predorsal area, first dorsal‐fin base and breast naked; δ‐pore missing; anterior point of the suborbital row b not reaching level of posterior point of suborbital row d; slightly emarginated caudal fin and nape coloration pattern. DNA barcode data clearly discriminate Pomatoschistus spp. in the neighbour‐joining tree with an average of 17·7% interspecific K2P distance. The most closely related taxon to P. nanus sp. nov. is Pomatoschistus bathi and the most distantly related is Pomatoschistus tortonesei with 11·9 and 21·9% K2P distances respectively. Morphometric and genetic data are also provided for Pomatoschistus bathi.     

Identification of a host-associated species complex using molecular and morphometric analyses,with the description of Gyrodactylus rugiensoides n. sp. (Gyrodactylidae,Monogenea)

Gyrodactylus rugiensis was originally described as a parasite occurring on the marine gobies Pomatoschistus minutus and Pomatoschistus microps. In our preliminary survey this species was also frequently found on Pomatoschistus pictus and Pomatoschistus lozanoi. Subsequent molecular analysis of the internal transcribed spacers rDNA region revealed that this parasite actually represents a complex of two apparently cryptic species, one restricted to P. microps and the other shared by P. minutus, P. lozanoi and P. pictus. Morphometric analyses were conducted on 17 features of the opisthaptoral hard parts of specimens collected from all four host species. Standard discriminant analysis showed a clear separation of both genotypes by significant differences in marginal hook and ventral bar features. Statistical classifiers (linear discriminant analysis and nearest neighbours) resulted in an estimated misclassification rate of 4.7 and 3.1%, respectively. Based on molecular, morphological and statistical analyses a new species, Gyrodactylus rugiensoides is described. This species seems to display a lower host-specificity than generally observed for Gyrodactylus species as it infects three sympatric host species.However, seasonal and host-dependent morphometric variation is shown for G. rugiensoides collected on P. pictus. Host-switching and gene flow might be important factors preventing speciation on closely related and sympatric host species. The presence of host associated species complexes in this Gyrodactylus-Pomatoschistus system is also confirmed by the presence of two host-dependent genotypes within G. micropsi found on P. minutus and P. lozanoi, and P. microps, respectively. By comparing host and parasite phylogeny, phylogenetic and ecological factors influencing host-specificity are discussed.     

The importance of gobies (Gobiidae,Teleostei) as hosts and transmitters of parasites in the SW Baltic

The parasite fauna of five goby species (Gobiidae, Teleostei) was investigated in the Baltic Sea during the period 1987 to 1990. 13 parasite species were found in samples from the Lübeck Bight:Bothriocephalus scorpii, Schistocephalus sp. (Cestoda);Cryptocotyle concavum, Cryptocotyle lingua, Podocotyle atomon, Derogenes varicus (Digenea);Hysterothylacium sp. (cf.auctum),Contracaecum sp.,Anisakis simplex (Nematoda);Corynosoma sp.,Echinorhynchus gadi, Neoechinorhynchus rutili, Pomphorhynchus laevis (Acanthocephala). The number of parasite species were: 10 in the sand gobyPomatoschistus minutus, 8 in the black gobyGobius niger, 7 in the two-spotted gobyGobiusculus flavescens, 6 in the common gobyPomatoschistus microps, and 5 in the painted gobyPomatoschistus pictus. Neoechinorhynchus rutili occurred only inP. minutus, andCorynosoma sp. only inG. niger. The extent to which the gobies were parasitized clearly depended on the respective ways of life and, moreover, on the kind of prey ingested by the hosts. Additionally, the age of the hosts might be important. The highest rate of parasitism, more than 60%, was reached byHysterothylacium sp. inG. niger and byCryptocotyle concavum inP. microps. Infestation incidence lay mostly below 40% which means a satellite species status (Holmes, 1991). The number of parasite species was highest in summer; the highest intensities of single parasites occurred in spring (Podocotyle atomon) or autumn (Crytocotyle concavum).Bothriocephalus scorpii, Hysterothylacium sp. andPodocotyle infested their juvenile hosts very early, but onlyHysterothylacium was accumulated byG. niger during its whole life span, whereasBothriocephalus persisted also in older gobies in low intensities. The cercariae ofCryptocotyle spp. penetrate actively into their hosts; all the other parasites named were transmitted in larval form by prey organisms which consisted mainly of planktonic and benthic crustaceans. The gobies were final hosts for only 5 parasites; but two species may be transmitted to larger fish, and 6 species to sea birds or mammals. The parasite community of the five gobies may possibly be taken to characterize the ecological quality of the environment of the Lübeck Bight.     

A redescription of Pomatoschistm norvegicus (Collett, 1903) (Teleostei: Gobioidei) based on syntype material

A deeper water species of the Mediterranean-Atlantic gobiid genus Pomatoschistus, P. norvegicus (Collett, 1903), is redescribed from syntype material, including details of the lateral-line system and a summary of geographical distribution. The systematic status of P. norvegicus is briefly discussed with reference to the other nominal species, P. minutus (Pallas) and P. lozanoi (De Buen), of the 'P. minutus' complex.