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•Extensive sampling of estuarine gobies around the Australian coastline.•Multiple lines of evidence for at least six cryptic species.•Major unrealized biodiversity occurs in the ...region and potentially abroad.•Diverse estuarine faunas need consideration with future development and management.
Snubnose gobies (genus Pseudogobius: Gobionellinae) are ubiquitous to, and important components of, estuarine ecosystems of the Indo-west Pacific. These small benthic fishes occur in freshwater, brackish and marine habitats such as mangroves, sheltered tide pools and lowland streams, and represent a model group for understanding the biodiversity and biogeography of estuarine fauna. To develop the species-level framework required for a concurrent morphological taxonomic appraisal, we undertook thorough sampling around the extensive Australian coastline, referenced to international locations, as part of a molecular systematic review using both nuclear and mitochondrial markers. The results indicate that while there are currently eight recognised species, the true diversity is close to double this, with a hotspot of endemism located in Australia. Complicated patterns were observed in southern Australia owing to two differing zones of introgression/admixture. Key drivers of diversity in the group appear to include plate tectonics, latitude, and historic barriers under glacial maxima, where an interplay between ready dispersal and habitat specialisation has led to regional panmixia but frequent geographic compartmentalisation within past and present landscapes. The findings have significant implications for biodiversity conservation, coastal and estuarine development, the basic foundations of field ecology, and for applied use such as in biomonitoring.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Western Atlantic goby Ctenogobius boleosoma (Jordan & Gilbert, 1882) was found at the Agri River mouth, south Italy. It is the northwesternmost record of an alien goby recorded in the ...Mediterranean Sea. The present record confirms the presence of C. boleosoma in the Mediterranean Sea, recently reported only by the DNA barcoding of larvae collected in the mesopelagic depths of the Levant Sea. The present record of adult individuals, including ripe females, indicates an established population present in shallow estuarine waters matching the species’ native habitat conditions. The morphology and coloration of Mediterranean C. boleosoma are described and discussed. A detailed description of the cephalic lateral-line system of C. boleosoma is given for the first time. Ten species of the Mediterranean alien gobies are most likely Lessepsian migrants. Three gobiid aliens are Indo-Pacific gobies not present in the Red Sea and probably introduced by shipping. The alien gobies include only one Atlantic species and the Eastern Atlantic ingression component is lacking compared to the other alien fishes in the Mediterranean Sea. Indo-Pacific gobies have been quite successful in the colonization in Mediterranean and in the establishment of the Levant populations. However, contrary to other alien fishes, gobies show limited distribution across the Mediterranean Sea, with almost all alien gobies still being restricted to the Levant.
Parasites have deleterious effects on their hosts, often resulting in altered host behavior or increased energy expenditure. When organisms are exposed to suboptimal environments, parasite loading ...may increase. Microbialite pools along the warm temperate South African coastline have been hypothesized as refugia for Epaulette gobies (Coryogalops sordidus, Gobiidae) when they are outside of their previously known subtropical distribution. The aim of this study was to determine if C. sordidus individuals infected with metacercarial cysts display higher metabolic rates or different swimming behavior compared to noninfected individuals. We measured each goby's swimming performance using a critical station‐holding speed (Ucrit) test (n = 60) and visually scored their swimming behavior (n = 52) during these measurements. Also, we measured the metabolic rate of gobies using an intermittent flow respirometer system to determine standard metabolic rate (SMR) and maximum metabolic rate (MMR) from gobies at 21°C before and after swimming trials. Metacercarial load carried by infected gobies seemingly had no impact on the host's energetics (SMR or MMR), swimming ability (as repeated Ucrit tests), or swimming behavior compared to noninfected gobies. Thus, the metacercarial intensity observed in gobies in the current study appeared to have no impact on host swimming performance or behavior. Furthermore, the swimming capacity observed for C. sordidus, in general, suggests that this goby is a poor swimmer compared to other gobiid species.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Winter mortality can be a strong selective pressure on animals living in temperate regions, especially for young and small individuals. Therefore, understanding the mechanism for its size-dependence ...is important to predict population dynamics of the species in a fluctuating environment. In this study, we experimentally investigated the effects of body size, temperature and energy reserve depletion on the overwinter mortality of young mudskipper fish (Boleophthalmus pectinirostris). Small size-class fish (<44 mm in SL) died earlier than large size-class fish (≥44 mm) under both heated and unheated temperature conditions. Relatively higher energy and lipid content in live compared to dead fish and suspended mortality during the warm period under unheated conditions suggested the effects of both energy depletion and low temperature on overwinter mortality. Small size-class fish showed a relatively higher energy depletion rate under both temperature conditions probably due to their higher mass-specific metabolic rate. Since small size-class fish died earlier than large size-class fish, the body size difference in energy depletion rate may be one of the factors affecting the size-dependence of overwinter mortality. The energy depletion rate gradually decreased with the progress of experiment, suggesting that fasting-induced metabolic depression occurred. The estimated relative lipid mass decreased with the progress of experiment. The lipid depletion rate with elapsed days significantly reduced in small size-class fish under unheated conditions comparing with large size-class fish, while the rate in large size-class fish was significantly larger than that of small size-class fish in heated conditions. The difference suggests the possibility that small size-class fish switches metabolic fuels at a relatively lower temperature condition to maintain a minimum activity level for unpredictable feeding opportunities during the pre-winter season.
•Small young mudskipper fish died earlier than large one during winter.•Early death of small fish may be caused by their higher energy depletion rate.•Fasting-induced metabolic depression may have occurred.•Lipid depletion rate was reversed between size classes depending on temperature.•Temperature-specific metabolic depression may improve survival of small fish.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•The most extreme specializations to terrestriality evolved twice.•Intermediate morphologies are independent adaptions to living in mud or the water margin, rather than transitional ...forms.•Oxudercinae (mudskippers) and Amblyopinae (eel gobies) are reciprocally paraphyletic; Oxudercinae is a junior synonym.
The initial vertebrate conquest of land by stegocephalians (Sarcopterygia) allowed access to new resources and exploitation of untapped niches precipitating a major phylogenetic diversification. However, a paucity of fossils has left considerable uncertainties about phylogenetic relationships and the eco-morphological stages in this key transition in Earth history. Among extant actinopterygians, three genera of mudskippers (Gobiidae: Oxudercinae), Boleophthalmus, Periophthalmus and Periophthalmodon are the most terrestrialized, with vertebral, appendicular, locomotory, respiratory, and epithelial specializations enabling overland excursions up to 14 h. Unlike early stegocephalians, the ecologies and morphologies of the 45 species of oxudercines are well known, making them viable analogs for the initial vertebrate conquest of land. Nevertheless, they have received little phylogenetic attention. We compiled the largest molecular dataset to date, with 29 oxudercine species, and 5 nuclear and mitochondrial loci. Phylogenetic and comparative analyses revealed strong support for two independent terrestrial transitions, and a complex suit of ecomorphological forms in estuarine environments. Furthermore, neither Oxudercinae nor their presumed sister-group the eel gobies (Amblyopinae, a group of elongated gobies) were monophyletic with respect to each other, requiring a merging of these two subfamilies and revealing an expansion of phenotypic variation within the “mudskipper” clade. We did not find support for the expected linear model of ecomorphological and locomotory transition from fully aquatic, to mudswimming, to pectoral-aided mudswimming, to lobe-finned terrestrial locomotion proposed by earlier morphological studies. This high degree of convergent or parallel transitions to terrestriality, and apparent divergent directions of estuarine adaptation, promises even greater potential for this clade to illuminate the conquest of land. Future work should focus on these less-studied species with “transitional” and other mud-habitat specializations to fully resolve the dynamics of this diversification.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Although longjaw mudsucker (Gillichthys mirabilis, Gobiidae) has been studied extensively for its ability to occupy low‐oxygen environments, few studies have addressed the evolution of its ...exceptionally elongated jaws that extend posteriorly beyond the gill opening in large adults. In this study, the ontogeny of the maxillae of G. mirabilis, Gillichthys seta, and the out‐group species Eucyclogobius newberryi was studied within the heterochrony framework using digitized landmarks and caliper measurements. The results show that the maxilla of both species of Gillichthys evolved via acceleration (increased growth rate) and that of G. mirabilis via hypermorphosis (continued growth to a larger body size); two forms of peramorphosis. This is in contrast to earlier studies that concluded that G. seta is paedomorphic. We were unable to confirm an earlier hypothesis of sexual dimorphism in the jaw length of G. mirabilis. The evolution of the elongated jaws and associated large buccopharyngeal membrane in G. mirabilis is hypothesized to increase the surface area for gas exchange during aerial respiration and may also serve to amplify the aggressive gaping display as observed in other fishes.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Three species of the genus Phyllodistomum Braun, 1899 are identified infecting marine teleost fishes from Sinop coast (southern Black Sea, Turkey). Those are Phyllodistomum acceptum from Parablennius ...sanguinolentus; Phyllodistomum crenilabri from Symphodus tinca and Symphodus ocellatus; and Phyllodistomum sp. from Gobius cruentatus. Standard parasitological investigation methods were implemented, and morphological diagnostic features of these species were studied in detail under both light microscope and scanning electron microscope. The measurement data of all morphological diagnostics are provided; photomicrographs of each part of the parasites are presented. Infection prevalence and intensity values are given, as well as morphometric data for each parasite species. This research is the first on Phyllodistomum sp. presence in Gobius cruentatus. Moreover, this study is the first one, in which the tegumental surface of P. acceptum and P. crenilabri was examined by scanning electron microscopy.
Biological invasions are frequently studied topics in ecological research. Unfortunately, within invasion ecology parasite-associated aspects such as parasite impacts on new environments and on local ...host populations are less well-studied. Round gobies migrating from the Ponto-Caspian region into the Rhine River system are heavily infested with the Ponto-Caspian acanthocephalan parasite Pomphorhynchus laevis. As shown by experimental infestations the acanthocephalans occur as pre-adults in host-encapsulated cysts within the internal organs of the migrating gobies, but remain infective for their definitive host chub. Recently, we described the occurrence of larvae of another parasite, the invasive eel swim bladder nematode Anguillicola crassus, in these Pomphorhynchus cysts. In the present study, we could prove the infectivity of the nematode larvae for European eels for the first time. After experimental inoculation of Pomphorhynchus cysts occasionally infested with A. crassus larvae, the nematodes grow to maturity and reproduce whereas all P. laevis were unviable. We therefore postulate that the nematode larvae behave like immunological hitchhikers that follow a "Trojan horse strategy" in order to avoid the paratenic host's immune response. Accordingly, the interaction between both invasive parasites gives first evidence that the invasional meltdown hypothesis may also apply to parasites.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Here, we combined archived mitochondrial sequences for Ponto-Caspian gobiids with new sequences from the south Caspian basin to assess and evaluate its gobioid diversity and taxonomy, and to provide ...a first mitochondrial-based phylogenetic and phylogeographic framework. We demonstrate that: (i)
Proterorhinus nasalis
is the tubenose goby taxon in the saline waters of the southern Caspian Sea, whereas the name
Pr. semipellucidus
for the Azov/northern Caspian Sea/Volga River populations is likely be resurrected depending on the outcome of an integrative taxonomical approach; (ii) the deep-water goby
Ponticola bathybius
should be re-assigned to the genus
Neogobius
, as it is the sistergroup of
N. melanostomus
; (iii) specimens previously identified as
Po. cyrius
and
Po. iljini
from the south Caspian basin appear conspecific with
Po. iranicus
and
Po. gorlap
, respectively, and should be omitted from the checklist of Iranian and south Caspian freshwater fishes; (iv) the low stand of the Caspian Sea during the Tyurkyanian regression is inferred to have led to the isolation and evolution of
Po. iranicus
; and (v) similarities in genetic background, and invasion history of
Rhinogobius
sp. and
Pseudorasbora parva
in Iran and Turkmenistan indicate that the initial introduction of both species into the region possibly originated from Japan in the 1980s.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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