The Gorgeous goby Lythrypnus pulchellus shows extreme sexual plasticity with the bidirectional sex‐change ability socially controlled in adults. Therefore, this study describes how the hierarchical ...status affects hormone synthesis through newborn hormone waste products in water and tests the influence of body size and social dominance establishment in sex reversal duration and direction. The associated changes in behavior and hormone levels are described under laboratory conditions in male–male and female–female pairs of similar and different body sizes, recording the changes until spawning. The status establishment occurred in a relatively shorter time period in male and female pairs of different sizes (1–3 days) compared to those of similar size (3–5 days), but the earlier one did not significantly affect the overall time of sex change (verified by pair spawning). The changes in gonads, hormones, and papilla occurred in sex‐changer individuals, but the first one was observed in behavior. Courtship started at 3–5 days in male pairs and from 2 h to 1 day in female pairs of both groups of different and similar sizes. Hormones did not gradually move in the new sexual phenotype direction during the sex‐change time course. Nonetheless, estradiol regulated sex change and 11‐ketotestosterone enabled bidirectional sex change and was modulated by agonistic interactions. Cortisol is associated with status and gonadal sex change. In general, similar mechanisms underlie sex change in both directions with a temporal change sequence in phases. These results shed new light on sex‐change mechanisms. Further studies should be performed to determine whether these localized changes exist in the steroid hormone synthesis along the brain–pituitary gonad axis during social and bidirectional sex changes in L. pulchellus.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
An in situ reciprocal transplant experiment was carried around a volcanic CO2 vent to evaluate the anti-predator responses of an anemone goby species exposed to ambient (∼380 μatm) and high ...(∼850 μatm) CO2 sites. Overall, the anemone gobies displayed largely unaffected behaviors under high-CO2 conditions suggesting an adaptive potential of Gobius incognitus to ocean acidification (OA) conditions. This is also supported by its 3-fold higher density recorded in the field under high CO2. However, while fish exposed to ambient conditions showed an expected reduction in the swimming activity in the proximity of the predator between the pre- and post-exposure period, no such changes were detected in any of the other treatments where fish experienced acute and long-term high CO2. This may suggest an OA effect on the goby antipredator strategy. Our findings contribute to the ongoing debate over the need for realistic predictions of the impacts of expected increased CO2 concentration on fish, providing evidence from a natural high CO2 system.
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•This is the first assessment in the wild of behavioural responses of fish acutely and chronically exposed to elevated CO2.•High density of anemone goby fish was recorded at high-CO2 levels off a volcanic CO2 vent in Vulcano island (Italy).•Acute and chronic exposure to elevated CO2 did not affect most of the behaviours in adult G. incognitus.•Behavioural plasticity occurred under ocean acidification conditions suggesting potential local adaptation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Day's goby, Acentrogobius dayi (one specimen) was obtained from a marsh near Al-Fuhud Village, south-west of Baghdad, Iraq. The presence of this species in the new habitat is considered a new ...record for Day's goby in the southern marshes of Iraq. Possibilities for such presence were presented.
The
Eviota
zebrina
complex includes eight species of closely-related dwarfgobies, four of which are herein described as new. The complex is named for
Eviota
zebrina
Lachner & Karnella, 1978, an ...Indian Ocean species with the holotype from the Seychelles Islands and also known from the Maldives, which was once thought to range into the Gulf of Aqaba and the Red Sea eastward to the Great Barrier Reef of Australia. Our analysis supports the recognition of four genetically distinct, geographically non-overlapping, species within what was previously called
E.
zebrina
, with
E.
zebrina
being restricted to the Indian Ocean,
E.
marerubrum
sp. nov.
described from the Red Sea,
E.
longirostris
sp. nov.
described from western New Guinea, and
E.
pseudozebrina
sp. nov.
described from Fiji. The caudal fin of all four of these species is crossed by oblique black bars in preservative, but these black bars are absent from the four other species included in the complex. Two of the other species within the complex,
E.
tetha
and
E.
gunawanae
are morphologically similar to each other in having the AITO cephalic-sensory pore positioned far forward and opening anteriorly.
Eviota
tetha
is known from lagoonal environments in Cenderawasih Bay and Raja Ampat, West Papua, and
E.
gunawanae
is known only from deeper reefs (35–60 m) from Fakfak Regency, West Papua. The final two species are
E.
cometa
which is known from Fiji and Tonga and possesses red bars crossing the caudal fin (but lost in preservative) and a 9/8 dorsal/anal-fin formula, and
E.
oculineata
sp. nov.
, which is described as new from New Guinea and the Solomon Islands, and possesses an 8/7 dorsal/anal-fin formula and lacks red caudal bars.
Eviota
oculineata
has been confused with
E.
cometa
in the past.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The Indo-West Pacific Glossogobius giuris(Hamilton, 1822) species complex has four spatially circumscribed independent lineages, partially taxonomically resolved. A sample of gobies from the G. ...giurisspecies complex was recently collected from the Makran River System, south-eastern Iran, which drains into the northern Oman Sea. The taxonomic status of thispopulation was clarified using a molecular and morphological framework. Molecular and morphological data both revealed that the examined sample from the Makran River System is conspecific with G. giurisB which is widely distributed in the coastal habitats and basins of the Indian Ocean. In addition, consensus from different molecular species delimitations, K2P genetic distance, and tree topologies confirmed the four lineages of the G. giuris species complex as distinct taxonomic entities, hereby highlighting the necessity of an integrative morphological and molecular approach to complete the clarification of taxonomic diversity within this group. Glossogobius giuris species complex taxonomy is discussed and solution recommended.
Polybrominated diphenyl ethers (PBDEs) are known to be broken down by debromination reactions in the natural environment, such as by photolysis, microbial and metabolic processes. Although ...species-specific debromination of PBDEs by fish has also been reported, it has only rarely been studied from the phylogenetic perspective. The objective of this study is to reveal the factors affecting species-specific debromination through validation between the bioaccumulation of PBDEs in muscle tissue and the ability to debrominate BDE99. As environmental observations, PBDE concentrations in muscle tissues were analyzed in 25 wild fish (Cyprinidae, Gobiidae and others). As in vitro experiments, debromination experiments were conducted using the hepatic microsomes of 21 fish species. Significant amounts of BDE99 were detected in almost none of the Cyprinidae. A relatively higher debromination ability was confirmed in the Cyprinidae in in vitro experiments. The Cyprinidae thus appears to be a family with high debromination ability. BDE99 has been detected in some goby species but not others. This pattern was also seen in in vitro experiments, suggesting that debromination ability is not consistent within the Gobiidae. In further quantitative comparisons, kinetic parameters such as Km and vmax were determined for selected fish species. The common carp (Cyprinus carpio) and the Japanese crucian carp (Carassius cuvieri), both Cyprinidae, showed higher vmax values, whereas vmax values among three Gobiidae diverged widely. A comparison of field observations and in vitro experiments, revealed the bioaccumulation ratio of BDE99 to be affected by the BDE99 debromination ability of each fish species. This is the first report on classification of BDE99 accumulation ratio by debromination ability and a phylogenetic species comparison based on kinetic parameters for debromination reactions of PBDEs by fish.
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•Comparison of PBDE accumulation in fish muscle and BDE99 debromination ability using hepatic microsomes•Most Cyprinidae did not accumulate BDE99, indicating a higher BDE99 debromination rate over the entire family.•In Gobiidae, bioaccumulation patterns and debromination ability varied widely according to species.•This study revealed phylogenetic diversity and conservation of debromination ability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
As one of the most abundant groups in marine fish families, Gobiidae fish are important fishery resources in China, and some are also invasive species in certain regions worldwide. However, the ...phylogenetic relationships of Gobiidae fish remain ambiguous, and the study of their invasion-related genes is still scarce. This study used high-throughput sequencing technology to conduct a whole-genome survey of five Gobiidae fish species:
,
,
,
, and
. De novo assembly of five fish genomes was performed, and genomic traits were compared through K-mer analysis. Among the five Gobiidae fish genomes,
had the largest genome size (1601.98 Mb) and the highest heterozygosity (1.56%) and repeat rates (59.83%). Phylogenetic studies showed that
was most closely linked to
, while Apogonidae and Gobiidae were closely related families. PSMC analysis revealed that
experienced a notable population expansion than the other four fish species in the Early Holocene. By using the KOG, GO, and KEGG databases to annotate single-copy genes, the annotated genes of the five fish were mainly classified as "signal transduction mechanisms", "cellular process", "cellular anatomical entity", and "translation".
,
, and
had more genes classified as "response to stimulus" and "localization", which may have played an important role in their invasive processes. Our study also provides valuable material about Gobiidae fish genomics and genetic evolution.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
On coral reefs, many small coral-associated fishes exhibit high levels of habitat specialisation, which can contribute to their susceptibility to habitat loss. However, high levels of habitat ...partitioning may buffer communities from the loss of particular habitat types. This study provides a quantitative evaluation of habitat specialisation, substratum selectivity and habitat overlap of 9
Eviota
(Gobiidae) species in Kimbe Bay, Papua New Guinea. All but 1 locally common
Eviota
species were strongly associated with scleractinian coral substrata, and species ranged from habitat generalists to obligate coral specialists with some of the most extreme fine-scale patterns of habitat specialisation known for coral reef fishes. Patterns of substratum selectivity varied greatly within the genus, but many species showed distinct preferences for particular corals, most notably the scleractinian genera
Acropora
and
Porites
. Most species exhibited low habitat overlap and partitioned habitat on a fine spatial scale, but there were notable exceptions. Two
Acropora
coral specialists and some species with strong preference for massive
Porites
coral exhibited high overlap. Overall, the local abundance of
Eviota
species varied in relation to the degree of habitat specialisation, with the most generalised species more abundant than the habitat specialists. Habitat structure and species-specific differences in habitat specialisation, substratum selectivity and habitat overlap are likely to be key drivers explaining the distribution and abundance of
Eviota
species and the local community structure. Most importantly, many coral-dependent and less abundant species of
Eviota
may be vulnerable to habitat loss as a result of the ongoing degradation of coral reefs.
Facultative air‐breathing fish can exchange respiratory gases using an air‐breathing organ (ABO), such as the oral cavity of the integument, during environmental hypoxia. The goby Gobionellus ...oceanicus inhabits areas subject to environmental hypoxia; however, its ABO is unknown. To investigate the respiratory potential of G. oceanicus, the gill and integument surface area, diffusion capacity, and their diffusion barrier thickness were measured. Our results show that although gill surface area is smaller than observed in other facultative air‐breathing fish, but it has all features necessary to perform aquatic gas exchange. Additionally the integument of the palate has a short diffusion barrier thickness and a large calculated O2‐diffusion capacity suggesting that it functions as the ABO.
In this figure it is might be observed the relevance of the palate integument for air breathing expressed by the ratio between surface area and body mass (A), surface area and volume (B), anatomical diffusion factor (C) and O2 diffusion capacity (D), when compared to other integument parts.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Morphology, physiology, and behavior are the primary axes of organismal diversification, and phenotypic differentiation among species in any of these dimensions can be indicative of where, when, and ...why species can occur and coexist. However, nuanced adaptations in superficially similar species can be difficult to pinpoint, especially for mobile animals in highly diverse ecosystems, such as coral reef fishes. In this context, morphology and behavior are often investigated to assess potential differences, but interspecific variation in physiological traits is not frequently considered. Here, we use field surveys, morphometrics, behavioral observations, gut content DNA metabarcoding, and metabolic rate trials to investigate phenotypic differentiation in 2 small sympatric species of sand-dwelling cryptobenthic coral reef fish. We show that the gobies
Fusigobius neophytus
and
Gnatholepis cauerensis
co-occur in sandy habitats throughout a coral reef lagoon in French Polynesia. While superficially similar, the 2 species differ in the length of their gastrointestinal tracts, their ingested prey, and their foraging rates. These differences are also reflected in the species’ standard and maximum metabolic rates:
G. cauerensis
has a longer intestinal tract and ingests more animal prey, has a more active foraging style, and displays markedly higher standard and maximum metabolic rates than
F. neophytus
. These results indicate clear differences in the functional niches of the 2 species, which are detectable across these 3 major organismal axes. Given the well-documented direct links between metabolic rate and organismal energy expenditure, we suggest that physiological traits may offer a useful additional dimension in the assessment of sympatric species and their functional roles.
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