Gobiid Fish Research Articles

New Genus and Species of Seven-Spined Goby (Gobiidae: Gobiosomini) from the Offing of the Amazon River, Brazil

Akko dionea, a new genus and species of gobiid fish, is described from the shelf waters of Brazil just northeast of the mouth of the Amazon River. It is a member of the Gobiosomini, an endemic American tribe with which it shares two synapomorphies: a 3-221110 dorsal pterygiophore formula and 11 precaudal vertebrae. Within this tribe, its relationships are obscured by a large number of autapomorphic features, some unknown in any other gobiids. The osteology of the head, pectoral and pelvic girdles, and the caudal region are described along with certain aspects of the cranial and girdle myology. The arrangement of sensory papillae is illustrated. The species lacks head pores. Parallelism in structures with other unrelated gobies are believed to reflect adaptations to life on a soft mud bottom. Alepidoeleotris tigris Herre is synonymized with Eleotrica cableae Gingburg, and Cayennia Savage is synonymized with Gobioides Lacep?de. T HE New World goby fauna is dominated by a single, large, endemic tribe, the Gobiosomini, a member of the subfamily Gobiinae (Pezold, 1993). The Gobiinae, containing about 100 genera worldwide, is represented in the Americas by 29 genera of which 26 are endemic. The Gobiosomini comprises 24 of these 26 endemic genera and represent some 40% of the total New World gobioid genera. Members of the Gobiosomini display a remarkable diversity in both form and habit and occupy habitats from fresh waters to shelf slopes at depths exceeding 500 meters. Here we report on a new and unusual genus of Gobiosomini from off the mouth of the Amazon River.

Complexity in Parasite Life Cycles: Population Biology of Cestodes in Fish

1. This paper examines the population biology of two related species of bothriocephalid cestodes, parasites of teleostean fish, which live in sympatry. One species, Bothriocephalus barbatus, needs in its life cycle only one obligatory intermediate host, a copepod. The second species, B. gregarius, needs the same intermediate host first, but also utilizes a non-obligatory paratenic host, which is a gobiid fish. In the case of B. gregaring, definitive hosts can be infested via the intermediate host or the paratenic host. A simple mathematical model was built to investigate the effect of the addition of a paratenic host into the life cycle of a parasite. 2. Results of the simulation clearly demonstrated that the maintenance or absence of infectivity of cestode larvae in the paratenic host could explain the observed levels of infection in both definitive hosts. 3. Acquisition of paratenic hosts has two advantages: the recovery of lost infective stages in a previously non-suitable intermediate host, and an increase in the time of infection during which the definitive host could be infected as the result of eating copepods in its planctonophagous juvenile existence and by eating gobies in its predaceous older stages. 4. Using the basic transmission rate as a measure of fitness, we also investigated the possibility of maturation of B. gregarius in the paratenic host, e.g. the acquisition of a new definitive host by the parasite. Basic transmission rates and numerical simulations suggest that there is no benefit for the parasite in evolving towards this strategy

Does gonad structure reflect sexual pattern in all gobiid fishes?

Does gonad structure reflect sexual pattern in all gobiid fishes?

Does gonad structure reflect sexual pattern in all gobiid fishes?

Does gonad structure reflect sexual pattern in all gobiid fishes?

Prior anesthesia impairs a chemically mediated fright response in a gobiid fish

Quinaldine and phenoxyethanol, two commonly used fish anesthetics, reduced the intensity of a chemically induced fright response in a marine goby. MS-222, an anesthetic that has been indicated as harmful to fish olfaction, had no significant effect. Understanding these effects must await further study, but it is clear that caution should be exercised. One should definitely not use quinaldine or phenoxyethanol instead of MS-222 in an effort to avoid harmful effects.

Parasite transfer from crustacean to fish hosts in the Lübeck Bight, SW Baltic Sea

Four helminth parasites out of 19 species found in the Lübeck Bight, Baltic Sea, were chosen for investigations on the transfer from invertebrate to small-sized fish hosts: larvae of the tapewormsSchistocephalus sp. andBothriocephalus sp. (Cestoda) living in planktonic copepods as primary hosts;Podocotyle atomon (Digenea) andHysterothylacium sp. (Nematoda) were found in benthic crustaceans, especiallyGammarus spp. These hosts were the prey of 3 gobiid fishes,Gobiusculus flavescens (feeding mainly on plankton),Pomatoschistus minutus (preferring benthos), andP. pictus (feeding more on plankton than benthos). Because the fishes selected smaller sizes of crustaceans, they ingested all stages of the copepods but only the smaller-sized groups of gammarids which were often less infested by parasites. In order to evaluate the probability for a fish to be parasitized by a helminth, an infestation potential index (IP) was calculated.Podocotyle atomon andHysterothylacium sp. revealed an IP which was far lower in gobies than expected when the prevalences of the previous hosts were taken into consideration. The IP of tapeworm larvae was mainly influenced by the feeding pressure of the gobiid predators, which might change with developmental stage and season. It is concluded that parasite transfer to the next host decreases when sizes of prey and predator differ only moderately. This mechanism can reduce the numbers of parasites transferred to less suitable or wrong hosts.

Spawning of two Pomatoschistus species (gobbidae) in relation to nest availability and depth: A field experiment

The spawning of two sympatric gobiid fishes, the sand goby Pomatoschistus minutus and the common goby Pomatoschistus microps was investigated in relation to nest availability and depth. In two field experiments, carried out in the northern Baltic proper during summer, empty shells of the mussel Mya arenaria were divided into three size groups and provided as spawning substrates. The shells were set out at different depths and at different densities. Spatial habitat partitioning by depth was found. The sand goby preferred the deeper bottoms (2.8 m) and the common goby spawned only in areas shallower than 1 m. The spawning of the two species was separated in time by about 6 weeks with an overlap at the beginning of July. Low water temperatures (∼10°C) in June probably delayed spawning in the common goby. The sand goby preferred the larger shells. The larger the shells, the larger was the number of eggs, i.e. the male potential reproductive success. The common goby preferred the smaller shells, and their potential reproductive success did not show a clear trend with increasing shell size. In both species, the mean number of shells used for spawning increased with increasing substrate density. The maximum nesting density was 21 nests per m 2 for the sand goby and 20 nests per m 2 for the common goby. The maximum total density for both species together was 23 nests per m 2. Interspecific competition for spawning substrates was minimized, as spawning was separated in time and each species preferred different sizes of shell. The intensity of spawning under the shells provided indicates that a lack of suitable substrates limits spawning by both species in this area. The larger sand goby is limited in particular by the lack of larger substrates, and is probably forced to spawn in shallow water when suitable shells do not occur in its preferred depth range.

Reproductive strategies and early development of three freshwater gobies

Three species of gobiid fish inhabit the freshwater Lake Trichonis of western Greece. Two of these species, Economidichthys pygmaeus and E. trichonis are endemic, and the third is the widespread Knipowitschia caucasica. There are habitat separations between the three species, E. pygmaeus and E. trichonis prefer vegetated areas, the first being fully demersal at all stages of development and the second being semi‐demersal. Knipowitschia caucasica prefers sandy bottoms and is distributed in shallower waters. Female E. pygmaeus and E. trichonis spawn in nests prepared by the males in the cavities of broken reeds. The males subsequently guard the eggs until they hatch, with females playing no role in parental care. Economidichthys trichonis is probably the smallest freshwater European species. Its eggs are ovoid, measuring about 0.64 × 0.58 mm, from which tiny, unpigmented and incompletely developed pelagic larvae hatch out after an incubation period lasting less than 1 day at a water temperature of 19.5° C. The eggs of E. pygmaeus are cylindrical and larger, measuring about 2.38 × 0.89 mm, from which relatively large, strongly pigmented and ontogenetically more advanced larvae hatch out after a longer incubation period. Both species reproduce only once in their lifetime, at the age of 1 year, and die shortly after spawning, but the breeding season involves several spawnings by each individual fish. These biological, developmental and reproductive characteristics are discussed in relation to current theories on evolution of life‐historics.

Reproductive strategies and early development of three freshwater gobies

Three species of gobiid fish inhabit the freshwater Lake Trichonis of western Greece. Two of these species, Economidichthys pygmaeus and E. trichonis are endemic, and the third is the widespread Knipowitschia caucasica. There are habitat separations between the three species, E. pygmaeus and E. trichonis prefer vegetated areas, the first being fully demersal at all stages of development and the second being semi-demersal. Knipowitschia caucasica prefers sandy bottoms and is distributed in shallower waters. Female E. pygmaeus and E. trichonis spawn in nests prepared by the males in the cavities of broken reeds. The males subsequently guard the eggs until they hatch, with females playing no role in parental care. Economidichthys trichonis is probably the smallest freshwater European species. Its eggs are ovoid, measuring about 0.64 × 0.58 mm, from which tiny, unpigmented and incompletely developed pelagic larvae hatch out after an incubation period lasting less than 1 day at a water temperature of 19.5° C. The eggs of E. pygmaeus are cylindrical and larger, measuring about 2.38 × 0.89 mm, from which relatively large, strongly pigmented and ontogenetically more advanced larvae hatch out after a longer incubation period. Both species reproduce only once in their lifetime, at the age of 1 year, and die shortly after spawning, but the breeding season involves several spawnings by each individual fish. These biological, developmental and reproductive characteristics are discussed in relation to current theories on evolution of life-historics.

Sex Change in Both Directions by Alteration of Social Dominance in Trimma okinawae (Pisces: Gobiidae)

AbstractThe mating system of the gobiid fish Trimma okinawae is one of polygynous hermaphroditism, in which the largest female of a social unit changes sex following the removal of the dominant male. Histological observations of the gonads however, revealed that males have an ovarian tissue within a functional testis. The occurrence of ovarian tissue in the functional male suggests that T. okinawae males should be able to revert back into being functional females. To test this prediction, we placed females in an aquarium and allowed them to change sex. After confirming sex change from female to male, we individually placed new males into another aquarium and added a larger male to each. Our experiments revealed that females change sex and become males upon the removal of dominant males, and that those males changed sex again and became females in the presence of larger males. Sex change in both directions may be advantageous when a male is forced to become subordinate following the take over of the social unit by a larger male.

Predation Risk Affects Mate Choice in a Gobiid Fish

Predation Risk Affects Mate Choice in a Gobiid Fish

Differences in the activity rhythms of juvenile gobiid fish,Chasmichthys gulosus, from different tidal localities

Activity patterns of intertidal gobiid fish,Chasmichthys gulosus, collected from different tidal localities, were recorded in a constant environment. Gobies collected from a rocky shore with a large tidal range and a regular tidal regime displayed a ca. 12 hour rhythm in their activity pattern. Gobies from a rocky shore with a small tidal range and an irregular tidal regime, however, did not clearly display any such rhythm. The ecological implications of such activity rhythms are discussed from the viewpoints of feeding and avoidance of predators.

Isozyme criteria in the testing of phyletic relationships between species of Gobius and related eastern Atlantic‐Mediterranean genera (Teleostei: Gobüdae)

Horizontal starch gel electrophoresis was employed to investigate allozyme variation at 19 isozyme loci, in nine closely‐related Atlantic‐Mediterranean gobiid fish species, to assess genetic relationships, and to compare this with a phyletic hypothesis based on morphological apo‐morphies. The species examined were Gobius niger, G. auratus, G. cruentatus, G. paganellus, Mauligobius maderensis, Zosterisessor ophiocephalus, Thorogobius ephippiatus, Padogobius martensii and P. nigricans. Various phenetic and cladistic analyses were performed on isozyme and morphological data. The phenetic and cladistic results from morphological data, and the cladistic results from isozyme data, were largely comparable, with P. martensü and P. nigricans forming a sister group to all the other taxa, species of Cobius forming a crown group within the latter, and stem lines formed by Mauligobius, Zosterisessor and Thorogobius, respectively. The isozymic estimates of genetic distance differed from these chiefly in the relative positions of Zosterisessor and G. auratus, which appear less similar to other species of Gohius. G. auratus shows many alleles which are unique within the genus Gobius; possible explanations for this are put forward. The position of nigricans as congeneric with Padogobius martensü is confirmed by both phenetic and cladistic analyses of isozyme data.

Comparative Cytology and Morphology of Seminal Vesicles in male gobiid fishes

Anatomical, histological and EM studies are presented on the male seminal vesicles of 111 species of gobies (Gobiidae, Teleostei). These vesicles, attached to the sperm-ducts, are lined with an excretory epithelium composed of three types of cells: 1) columnar cells with giant Golgi cisterns in the form of large rings apical to the nucleus; 2) excretory cells with remarkably interdigitative basal lamina, that resemble sperm-duct cells; and 3) groups of interstitial, Leydig-type cells that possibly form a part of the mesorchial gland. Morphologically the vesicles appear to be taxa specific, the simplest one in the form of a few tubules on the sperm duct, and the most elaborate one forming large, wing-like structures, with an elaborate mass of passages. In many species the final form of the vesicles develops during the fish ontogenesis; in others, the form of this organ does not change during the lifetime of the fish. With the onset of reproduction, secretion and sperm accumulate in the tubule of the seminal vesicle and are expelled from there onto the eggs during fertilization. The comparative morphology, as well as possible ecological and physiological role of this secretion is discussed.

人工種苗放流マダイに見られるなわばり行動

We observed the behaviours of released juvenile red sea bream Pagrus major, stocked in a small fishing port. Three types of individuals showing distinct behaviours were distìnguished: 1) territorial individuals, 2) territorylike individuals, 3) individuals keeping no restricted cruising area. A portunid crab Thalamita sima and/or gobiid fishes were observed to dig the sandy substratum to make their shelters at the center of the defended area of the territorial individuals. This behaviour might make deep burrowing benthos to which P. major cannot generally gain access readily available to the territorial ones. The territorial individuals tended to defend smaller area, attack more frequently and show smaller number of feeding bout than the territorylike ones. Concerning the territorylike individuals, as the density became lower, the defended area of each individual became larger, but the number of both attacks and feedings smaller.

Comparative Cytology and Morphology of Seminal Vesicles in Male Gobiid Fishes

Comparative Cytology and Morphology of Seminal Vesicles in Male Gobiid Fishes

Redescription of Coryphopterus tortugae (Jordan) (Osteichthyes: Gobiidae), A Valid Species of Goby from the Western Atlantic

New descriptive and ecological information obtained from western Atlantic (mainly Colombian Caribbean) material has led to the recognition of Coryphopterus tortugae (Jordan) as a valid species of gobiid fish. It is distinguished from Coryphopterus glaucofraenum Gill, the species with which it was previously confused, by its more elongated shape, its pigmentation characteristics, and its more restricted habitats.

Yugoslavian and other records of the Italian freshwater goby,Padogobius martensii, and a character polarization in gobioid fishes

Padogobius martensii, a freshwater gobiid fish from the Po basin and adjoining rivers of northeastern Italy, is now recorded from Yugoslavia (Dalmatia), and further rivers of the Italian Adriatic seaboard. Diagnostic features are summarized, with special reference to another freshwater goby of the area, Orsinigobius punctatissimus. The origin of the Dalmatian populations is discussed with reference to sea-level changes in the postglacial Adriatic basin. Meristic polymorphism in dorsal pterygiophore sequence is described in the various P. martensii populations and its significance noted for polarization of character states in this feature.

Reproduction under predation risk in the sand goby, Pomatoschistus minutes, and the black goby, Gobius niger: the effect of age and longevity

In aquarium experiments, the two marine gobiid fish species Pomatoschistus minutus and Gobius niger were allowed to build nests and to spawn in the presence and absence of a predator (cod, Gadus morhua); behind a glass wall the predator was kept where it could be clearly seen by the gobies and vice versa. P. minutus showed no difference in number of nests or number of spawnings in the different treatments; approximately half of the males built nests, and the females spawned in half of those nests. G. niger, on the other hand, responded differently to the simulated predation risk. No nests were built in sight of the predator, whereas in the absence of predators, half of the males built nests and received eggs. The G. niger individuals in this experiment were 2–3 years old. However, when comparing the reproduction of G. niger of different age in the presence of a predator, older individuals (4–5 years) spawned, whereas younger (2–3 years) did not. No difference in vulnerability towards predators was found between equal-sized P. minutus and G. niger. The optimal behavior during the breeding season must depend on prospects of survival, based both on maximal lifespan and vulnerability to predation.

Systematics of freshwater gobies from Greece (Teleostei: Gobiidae)

Five species of gobiid fish are recognized in the fresh waters of Greece. Most distinctive is the south‐western Hellenic (West Balkanian component) endemic genus Economidichthys Bianco, Bullock, Miller & Roubal, 1987, with the type‐species E. pygmaeus (Holly, 1929) from Lefkas, Epirus and Lake Trichonis, and E. trichonis sp. nov., from Lake Trichonis, the latter probably the smallest freshwater European teleost at maturity (female, 18·0 mm) and maximum size (male, 30·0 mm). In tributaries of the northern Aegean basin (north‐eastern Hellenic freshwater fauna), two species of the Ponto‐Caspian genus Knipowitschia can be identified, the widespread Kn. caucasica (Kawrajsky in Berg, 1916) (coastal plain of Macedonia and Thrace) and the endemic Kn. ihessala (Vinciguerra, 1921) (Pinios river system, Thessaly). The larger Ponto‐Caspian tubenose goby, Prolerorhinus marmoratus (Pallas, 1811), occurs in the Evros (= Maritsa) (Thrace) and Strymon (Macedonia) systems. Only the genera Economidichthys and Knipowitschia are considered in this paper, being redefined in terms of osteology and head lateral‐line system, and the species described in detail, with special reference to meristic variation and squamation, and, in Economidichthys, the unique perianal organ of this genus. The relationships of Economidichthys and Kn. thessala are discussed and possible scenarios for their evolution are suggested in the light of Miocene to Recent events.