Research Article |
Corresponding author: Atsunobu Murase ( atsunobu.m@gmail.com ) Academic editor: Sven Kullander
© 2017 Atsunobu Murase, Ryohei Miki, Hiroyuki Motomura.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Murase A, Miki R, Motomura H (2017) Southern limits of distribution of the intertidal gobies Chaenogobius annularis and C. gulosus support the existence of a biogeographic boundary in southern Japan (Teleostei, Perciformes, Gobiidae). ZooKeys 725: 79-95. https://doi.org/10.3897/zookeys.725.19952
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Understanding the distributional patterns of individual animal groups with respect to coastal topology and the local physical environment provides essential foundational frameworks for marine zoogeography. In the northwestern Pacific waters of Japan, the distributional pattern of some cool-temperate species of marine fishes suggests the existence of a biogeographic boundary corresponding to a long sandy shore on the eastern coast of Kyushu, southern Japan. The existence of this hypothetical biogeographic boundary was tested by mapping the southern distributional limit of two species of cool-temperate intertidal gobies, Chaenogobius annularis and C. gulosus, which are endemic to East Asia and common in rock pools within their range in the Japanese Archipelago. Distribution and abundance were assessed by survey of museum collections from south-east Kyushu (i.e., the entire coasts of Kagoshima and Miyazaki prefectures); and a quantitative survey of the abundance of these gobies in rock pools at various sites around the hypothesized boundary on the eastern coast of Kyushu, including the subtropical Tanega-shima Island. The museum collection survey showed different distribution patterns between the two species: C. annularis was distributed along the entire coasts of south-east Kyushu including subtropical islands, whereas C. gulosus was distributed along these coasts, including one site on a subtropical island, except for an area south of the hypothesized boundary on the eastern coast of Kyushu. The density and occurrence rates of C. annularis in rock pools decreased with latitude, it being absent from a subtropical island, and C. gulosus was not detected from sites south of the hypothesized boundary. The qualitative survey showed that the southernmost records of C. annularis and C. gulosus were the adjacent subtropical islands (Yaku-shima and Tanega-shima islands respectively), although the quantitative survey suggested that their normal range of distribution was limited to the southern part of the Kyushu mainland. A combination of qualitative and quantitative survey methods in the present study highlighted that the southernmost record of a certain species may not necessarily indicate the true limit of its distribution. The distribution of C. gulosus supports the existence of the hypothetical biogeographic boundary, and the different distribution patterns of the two species may be caused by differences in their early life histories.
Distributional range, northwestern Pacific, rock pools
The delineation and characterization of the marine fauna is one of the objectives of marine zoogeography (
Intertidal organisms are generally easily accessible, and readily available to be sampled and used as ecological and biogeographic indicators (
The East Asian endemic genus Chaenogobius Gill, 1859, is composed of two species, C. annularis Gill, 1859, and C. gulosus (Sauvage, 1882) (Fig.
Conventional information on the distributional range of the two species of Chaenogobius (sensu
Laboratories of the Kagoshima University Museum and the Nobeoka Marine Science Station, University of Miyazaki, have collected specimens of fish species inhabiting coastal zones of Kagoshima and Miyazaki prefectures, south-east Kyushu. The specimens were deposited in fish collections of public museums, both the Kagoshima University Museum (
A long, sandy shore, measuring about 50 km in length from north to south, lies at the centre of the Miyazaki Prefecture coast (Fig.
Generally, five rock pools were sampled at each designated sampling site, except for the two sites on Tanega-shima Island, where 2–4 rock pools were sampled at each site. The total number of rock pools investigated during the seasons differed at each site, as the same pools were not sampled each time; some tide pools were inaccessible on certain sampling occasions due to costal weather conditions, such as high waves, and at these times, a neighbouring rock pool was selected. Across the sampling sites, tide pools were selected to be as similar as possible in mean size and elevation, following the methods of
Geographical distribution obtained from museum specimens is shown in Fig.
Records (circles and a triangle) of Chaenogobius annularis (left) and C. gulosus (right) in south-east Kyushu, southern Japan, based on the examination of museum specimens (qualitative survey). A triangle indicating occurrence of C. gulosus in Tanega-shima Island by possible human-induced transportation.
Rock pool volumes for the quantitative survey ranged from 0.06 to 0.76 m3 (n = 5, mean ± SD: 0.47 ± 0.33 m3), 0.31 to 1.01 m3 (n = 5, 0.72 ± 0.32 m3), 0.08 to 5.92 m3 (n = 7, 1.73 ± 2.54 m3), and 0.12 to 4.13 m3 (n = 8, 1.14 ± 1.33 m3) in Oita, N-Miyazaki, S-Miyazaki, and Tanega-shima respectively. Rock pool heights (pool surface height at low tide; see fig. 1 in
Results of quantitative samplings in rockpools at four sites on the eastern coast of Kyushu, southern Japan. Solid bars and plots show mean density (error bars indicating standard error) and occurrence rates of each species of Chaenogobius (upper, C. annularis; lower, C. gulosus) at each site in the two seasons (left, spring; right, autumn) respectively. Abbreviations of the sites on the x-axis are as follows: Ot, Oita; N-My, N-Miyazaki, S-My, S-Miyazaki; TnI, Tanega-shima (these locality names correspond to those used in Fig.
The qualitative and quantitative surveys showed different distribution patterns between the two species of Chaenogobius. The qualitative survey showed C. annularis to be distributed along almost the entire coasts of south-east Kyushu including Osumi Islands (both Yaku-shima and Tanega-shima islands), whereas the distribution of C. gulosus on the eastern coast of Kyushu was restricted to a northern area around Kadogawa Bay, north of the HBB, and among Osumi Islands; this species was recorded from only a single site at Tanega-shima Island (Fig.
Images of juveniles of the two species of Chaenogobius on the coasts of Kyushu, southern Japan: A Chaenogobius annularis, fresh specimen,
The distribution patterns and proportion of occurrence in the two species of Chaenogobius reported in this study indicate the difference of distribution range of the two species at their southernmost limit, even though they are both categorized as cool-temperate species, and provided implications for the different effects of a biogeographic barrier to each species. In addition to a species/genus level test, comprehensive ichthyofaunal surveys along the coast of Kyushu using qualitative and quantitative methods could clarify the effects of the biogeographic barrier suggested here, and as well as further define variation in physical factors along the Kuroshio Current that influence the formation of coastal fish communities.
The authors would like to express sincere thanks to members of Miyazaki City Fishermen’s Cooperative, Fisheries Cooperative Association of Iorigawa and Usuki Branch of Oita Fishermen’s Cooperative for permitting field surveys, members of KAUM for their help in examining museum specimens, Yukiya Ogata (University of Miyazaki) for field sampling efforts, Hiroshi Senou (KPM) for his help in depositing specimens and photos, Masahiro Aizawa (Biological Laboratory, Imperial Household Agency) for providing voucher information on a past study, and the staff of the Hydrographic and Oceanographic Department of the 10th Regional Coast Guard Headquarters (Kagoshima, Japan) who provided tidal information for the study sites. We also sincerely thank Gordon Yearsley (Ellipsis Editing, Australia) for the English revision of an early draft, anonymous reviewers and Sven Kullander for their valuable comments on the manuscript. This research was partly supported by JSPS KAKENHI Grant Number 15H06514, Fujiwara Natural History Foundation, and the Sasakawa Scientific Research Grant from The Japan Science Society (Grant Number: 29-737), and performed as a part of the project “Research for understanding coastal fish diversity and ecology of the crested murrelet in Kadogawa Town, northern part of Miyazaki Prefecture” supported by Kadogawa Town.
List of voucher specimens of Chaenogobius annularis for distribution records in south-east Kyushu by examination of museum collections
Data type: PDF
Explanation note: Lots of specimens ordered according to longitude. Number of KPM-NR indicates photographs of fresh specimens deposited in KPM.
List of voucher specimens of Chaenogobius gulosus for distribution records in south-east Kyushu by examination of museum collection
Data type: PDF
Explanation note: Lots of specimen ordered according to longitude. Number of KPM-NR indicating photographs of fresh specimen deposited in KPM.
List of voucher specimens of Chaenogobius annularis from quantitative surveys at rockpools on the eastern coasts of Kyushu
Data type: PDF
Explanation note:
List of voucher specimens of Chaenogobius gulosus from quantitative surveys at rockpools on the eastern coasts of Kyushu
Data type: PDF
Explanation note: