Fremde Fische in Flüssen und Seen

Non‐native fishes in rivers and seas The number of non‐native fish species in our water bodies is increasing in the course of globalisation. They navigate artificial canals, travel in ballast water of ships or are displaced as eggs attached to ships and other materials. Many of these species remain unnoticed but some may establish a reproductive population and even cause harm. Invasive gobies from the Black Sea – especially the bighead goby and round goby – are taken as an example to explain how biology and ecology can be studied and how we proceed to estimate the potential risk. Simple egg traps may help to reduce dispersal of these fish. Such measures are especially promising at locations such as the Upper Rhine where hydropower dams present bottlenecks.     

Equivalent whole-body concentrations of 11-ketotestosterone in female and male coral goby Gobiodon erythrospilus, a bidirectional sex-changing fish

The relationship between whole-body concentrations of 11-ketotestosterone (11-KT) and sexual function was examined in the coral goby Gobiodon erythrospilus , a bi-directional sex-changing fish. 11-KT occurred in both female and male G. erythrospilus , but levels were not always higher in males than in females within heterosexual pairs, and were not related to the stage of gonadal development of individual fish. These results suggest that comparable 11-KT levels in both sexes may allow serial adult sex change to take place in bi-directional sex-changing species, such as Gobiodon spp.     

Differential modes of selection on the rhodopsin gene in coastal Baltic and North Sea populations of the sand goby,Pomatoschistus minutus

An excellent model to elucidate the mechanisms and importance of evolution in the marine environment is the spectral tuning mechanism of the visual pigment in vertebrates. In the sand goby Pomatoschistus minutus (Teleostei; Gobiidae), a distribution‐wide study showed that spatial variation at the rhodopsin gene (RH1) matches the characteristics of specific light environments. This match suggests that populations are locally adapted to selective light regimes targeting the RH1 gene. If so, then the direction of selection should depend on the regional spatial and temporal stability of the light conditions. We tested this prediction by comparing goby populations from two regions: the Baltic Sea, characterized by divergent, but temporally stable light conditions, and the North Sea, characterized by locally heterogeneous and temporally variable light conditions. RH1 sequences of 491 Pomatoschistus minutus individuals from 15 locations were analysed. We found that variation at the RH1 gene in the Baltic populations showed signatures of diversifying selection, whereas the RH1 gene in the North Sea showed signatures of stabilizing selection. These different modes of selection are consistent with the regional light conditions and hence support our predictions, but may also be influenced by migration between the open sea and more turbid estuarine environments. An interesting observation is that within one gene, synonymous and non‐synonymous SNPs show a totally different pattern between populations. Population differentiation based on non‐synonymous SNPs of the RH1 gene correlated with spectral variation of the local environment of the sand goby populations. In contrast, the differentiation based on synonymous SNPs of RH1 reflects more the neutral historical pattern of the species.     

A new record of Gobius jarosi (Teleostei,Gobiidae) from the Early Miocene of Poland with inference to paleogeography and palaeoecology of the Carpathian Basin

Abstract

Gobies (family Gobiidae) were in the past and now important components of marine ecosystems as an essential part of the food chain. However, the early fossil record of this group is relatively meager, with only scarce skeletal remains. The oldest known representative of the genus Gobius has been recently described from the Early Miocene of Czech Republic as Gobius jarosi P?ikryl & Reichenbacher, 2018. Here we present a detailed study of a well-preserved goby skeleton of the same age from the Harta locality (Poland). This specimen is assumed as belonging to Gobius jarosi based on its almost complete morphological and meristic identity with the type material from the Vá?any nad Litavou locality. Some aspects of the paleogeography and paleoecology of the Early Miocene fish assemblage from Harta with special reference to the Carpathian Basin are also discussed in this paper.     

First record of a landlocked population of marine Millerigobius macrocephalus (Perciformes: Gobiidae): Observations from a unique spring-fed karstic lake (Lake Vouliagmeni, Greece) and phylogenetic positioning

A hitherto undescribed population of gobies in the Greek brackish karstic Lake Vouliagmeni was identified as Millerigobius macrocephalus. Molecular phylogenetic analysis using partial mitochondrial ribosomal DNA sequences situates this species as a sister taxon to Zebrus zebrus, thus confirming earlier morphological work. Morphological variation as compared to previous studies on this species is discussed. This is the first report of M. macrocephalus occurring inland and under oligohaline conditions, underlining that our knowledge on diversity and distribution of the European gobiid fauna is still far from complete. The occurrence of this rarely observed fish species might enhance the conservational importance of the lake under study.     

Does sympatry affect trophic resource use in congeneric tidepool fishes? A tale of two gobies Favonigobius lentiginosus and Favonigobius exquisitus

The feeding ecology of two sympatric gobies, Favonigobius lentiginosus and Favonigobius exquisitus, which inhabit soft substrate pools was studied in Moreton Bay, Australia. Favonigobius spp. and sediment cores were collected from three locations within the bay and fish gut contents were analysed to explore potential competition and ontogenetic dietary shifts. The most abundant prey at all sites was nematodes at 6.33 ± 0.38 cm(-3) at Dunwich, 33.58 ± 0.26 cm(-3) at Manly and 6.36 ± 0.849 cm(-3) (mean ± S.E.) at Godwin Beach. Nevertheless, they were not a dominant component of the diets. Volumetric percent contribution of prey showed that copepods and decapod shrimps dominated F. lentiginosus diets at Dunwich (7.8 and 6.6%, respectively) and Godwin Beach (6.5 and 14.3%, respectively) and the diets of F. exquisitus at Manly (9.2 and 9.5%, respectively) and Godwin Beach (10.4 and 11.8%, respectively). Schoener's index of dietary overlap between the two species, when sympatric, was 0.85 indicating a high similarity. An ontogenetic shift towards larger prey items occurred as Favonigobius spp. reached larger sizes. Gut fullness indices showed significant differences between time of day (two-way ANOVA, P < 0.01) and species (two-way ANOVA, P < 0.05) but Bonferroni's multiple comparison test showed that the only significant difference was between F. lentiginosus at Dunwich and F. exquisitus at Godwin Beach at 1800 hours. Food resource competition and temporal resource partitioning did not appear to be a limiting factor between F. lentiginosus and F. exquisitus despite cohabitation in such restricted environments.     

Molecular phylogeny of the gobioid fishes (Teleostei: Perciformes: Gobioidei)

The phylogeny of groups within Gobioidei is examined with molecular sequence data. Gobioidei is a speciose, morphologically diverse group of teleost fishes, most of which are small, benthic, and marine. Efforts to hypothesize relationships among the gobioid groups have been hampered by the prevalence of reductive evolution among goby species; such reduction can make identification of informative morphological characters particularly difficult. Gobies have been variously grouped into two to nine families, several with included subfamilies, but most existing taxonomies are not phylogenetic and few cladistic hypotheses of relationships among goby groups have been advanced. In this study, representatives of eight of the nine gobioid familes (Eleotridae, Odontobutidae, Xenisthmidae, Gobiidae, Kraemeriidae, Schindleriidae, Microdesmidae, and Ptereleotridae), selected to sample broadly from the range of goby diversity, were examined. Complete sequence from the mitochondrial ND1, ND2, and COI genes (3573 bp) was used in a cladistic parsimony analysis to hypothesize relationships among the gobioid groups. A single most parsimonious topology was obtained, with decay indices indicating strong support for most nodes. Major phylogenetic conclusions include that Xenisthmidae is part of Eleotridae, and Eleotridae is paraphyletic with respect to a clade composed of Gobiidae, Microdesmidae, Ptereleotridae, Kraemeriidae, and Schindleriidae. Within this five-family clade, two clades are recovered. One includes Gobionellinae, which is paraphyletic with respect to Kraemeriidae, Sicydiinae, Oxudercinae, and Amblyopinae. The other contains Gobiinae, also paraphyletic, and including Microdesmidae, Ptereleotridae, and Schindleriidae. Previous morphological evidence for goby groupings is discussed; the phylogenetic hypothesis indicates that the morphological reduction observed in many goby species has been derived several times independently.     

The phylogeny of a reduced ‘sand goby’ group based on behavioural and life history characters

Phylogenetic analysis of 27 behavioural and life history traits for five Mediterranean sand goby species (Perciformes, Gobiidae) produced one tree with a consistency index (excluding uninformative characters) of 0.756. This tree agreed with previous molecular analyses in providing strong support for the monophyly of the sand gobies, indicating that Pomatoschistus and Knipowitschia are paraphyletic and helping to resolve the ambiguous position of Economidichthys pygmaeus, placing it as the basal member of the reduced data set. Although the tree was completely resolved, the branches above E. pygmaeus were only moderately supported in the bootstrap analysis. Overall, the behavioural data provide information that may eventually help clarify the speciation bursts within the Mediterranean sand goby clade as much as is possible. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 916–924.     

Sperm‐duct gland secretion of the grass goby Zosterisessor ophiocephalus exhibits antimicrobial activity

The grass goby Zosterisessor ophiocephalus sperm‐duct gland extract displayed antimicrobial activity against gram‐positive and gram‐negative bacteria. This suggests that sperm‐duct gland mucins might be functional in protecting eggs and possibly parents from pathogens, an activity of great adaptive value for Z. ophiocephalus, which lays eggs in mud nests.