Sicyopterus stimpsoni

Sicyopterus stimpsoni
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Gobiiformes
Family: Oxudercidae
Genus: Sicyopterus
Species:
S. stimpsoni
Binomial name
Sicyopterus stimpsoni
(T. N. Gill, 1860)
Synonyms
  • Sicydium stimpsoni T. N. Gill, 1860
  • Sicydium albotaeniatum Günther, 1877
  • Sicydium nigrescens Günther, 1880
  • Vitraria clarescens D. S. Jordan & Evermann, 1903

Sicyopterus stimpsoni, commonly known as the Nopili rockclimbing goby, oopu nopili, or Stimpson's goby, is a species of amphidromous goby endemic to the islands of Hawai‘i. This species can reach a length of 19.8 centimetres (7.8 in) SL.[2]

Ecology

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Juveniles move from saltwater to freshwater streams shortly before changes in the anatomy of their mouths make eating plankton impossible. Their dietary behaviour depends critically on the benthic algal cycle, which is locked into the hydrological cycles of the island streams.[3]

The species in its adult form is found in the upper parts of clear, fast-running mountain streams, where there is clean gravel and rocks with no sedimentation, allowing the growth of algae on rock surfaces. It is found on all the Hawaiian Islands, although it has become rare on O‘ahu. The species is herbivorous, feeding only on diatoms and filamentous algae, and vigorously defending its feeding patch. The fish cultivate gardens on the upper surfaces of stones and boulders. Here they encourage a short turf of diatoms, filamentous algae and blue-green algae. The males guard these territorial gardens and they play a part in courtship.[4]

The males display brilliant blue and red colours during the breeding season, colours which change with the mood of the fish. The females attach their eggs to rocks where they are fertilised by the males, and the hatchlings are immediately washed downstream into the sea, where they develop, later to return to the freshwater pools upstream, where they live for several years. To arrive at these pools the juveniles need to climb the vertical rock under and beside very high waterfalls. The climbing is postponed until their mouthparts have moved from a forward-facing position to under the body. This change is effected in two days, altering their diet from that of an omnivore to feeding almost exclusively on algae growing on the rock surfaces, and not coincidentally enabling them to ascend slippery waterfall rocks by using mouth and pelvic suckers.[4]

It is preyed upon by black-crowned night herons and during its upstream migration through the estuary by Caranx spp., Polydactylus sexfilis and Sphyraena barracuda.[5]

Conservation

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Five of the seven native freshwater fish species on Hawaii are gobioid.[6] Three of these gobioids, S. stimpsoni (this article), Awaous stamineus (endemic) and Lentipes concolor (endemic) are amphidromous stream dwellers, which are adapted to the steep torrents of Hawaii's mountains (Eleotris sandwicensis and Stenogobius hawaiiensis, both endemic, are unable to pass steep torrents).[7] This makes them extremely sensitive to habitat disturbance.[6]

Etymology

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The specific name honours the marine biologist William Stimpson (1832-1872), who was the collector of the type specimen.[8]

References

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  1. ^ World Conservation Monitoring Centre (1996). "Sicyopterus stimpsoni". IUCN Red List of Threatened Species. 1996: e.T44167A10866562. doi:10.2305/IUCN.UK.1996.RLTS.T44167A10866562.en. Retrieved 16 November 2021.
  2. ^ Froese, Rainer; Pauly, Daniel (eds.). "Sicyopterus stimpsoni". FishBase. June 2013 version.
  3. ^ Julius, M. L.; Blob, R. W.; Schoenfuss, H. L. (2005). "The survival of Sicyopterus stimpsoni, an endemic amphidromous Hawaiian gobiid fish, relies on the hydrological cycles of streams: Evidence from changes in algal composition of diet through growth stages fish". Aquatic Ecology. 39 (4): 473. Bibcode:2005AqEco..39..473J. doi:10.1007/s10452-005-9007-1. S2CID 35007961.
  4. ^ a b Patzner, Robert; Van Tassell, James L.; Kovacic, Marcelo; Kapoor, B.G. (2011). The Biology of Gobies. CRC Press. pp. 256–261. ISBN 978-1-4398-6233-9.
  5. ^ "Sicyopterus stimpsoni". Hawaii Biological Survey, Bishop Museum. Retrieved February 28, 2012.
  6. ^ a b Nicolette Craig (May 18, 2011). "The amazing rock-climbing gobies". Practical Fishkeeping. Archived from the original on March 14, 2012. Retrieved February 28, 2012.
  7. ^ Fitzsimons, J. M.; and McRae, M. G. (2007) Behavioral Ecology of Indigenous Stream Fishes in Hawai‘i. Environmental Studies 3: 11–21.
  8. ^ Christopher Scharpf & Kenneth J. Lazara (24 July 2018). "Order GOBIIFORMES:Family OXUDERCIDAE (p-z)". The ETYFish Project Fish Name Etymology Database. Christopher Scharpf and Kenneth J. Lazara. Retrieved 12 September 2018.
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