Territory Stories

Nature Territory

Details:

Title

Nature Territory

Other title

Newsletter of the Northern Territory Field Naturalists' Club Inc.

Creator

Northern Territory Field Naturalists' Club Inc.

Collection

Nature Territory; Nature Territory; E-Journals; PublicationNT

Date

2018-03-01

Notes

Made available via the Publications (Legal Deposit) Act 2004 (NT).; This publication contains many links to external sites. These external sites may no longer be active.

Language

English

Subject

Natural history; Northern Territory Field Naturalists' Club; Periodicals

Publisher name

Northern Territory Field Naturalists' Club Inc.

Place of publication

Darwin

Volume

Newsletter, March 2018

File type

application/pdf

Use

Copyright

Copyright owner

Northern Territory Field Naturalists' Club Inc..

License

https://www.legislation.gov.au/Details/C2019C00042

Parent handle

https://hdl.handle.net/10070/299759

Citation address

https://hdl.handle.net/10070/381403

Page content

Page 10 Nature Territory - March 2018 Beast of the Month ? Lidwill?s Dwarf Goby Text and photos by Adam Bourke Amongst the 35 or so goby species inhabiting Darwin?s mangrove forests (Larson et al. 2013), Lidwill?s Dwarf Goby is without a doubt the most charming - at least in my opinion. Typically growing to litt le over 12 mm in length, Pandaka lidwilli is a tiny f ish indeed. The genus Pandaka contains the smallest of all known goby species, some of which were long thought to be the tiniest f ish on the planet. In the mid-2000s however, two even smaller groups of f ishes were discovered in peat swamps in Indonesia, and near coral outcrops on the Great Barrier Reef. And so, Pandaka gobies lost their t it le. Lidwill?s Dwarf Goby is a brackish-water f ish associated with mangroves and estuaries throughout parts of the Indo-Pacif ic region from Japan to Australia. Around Darwin, estuarine gobies are typically found amongst seaward fringing mangroves and Rhizophora forests, l iving in shallow pools and puddles near the base of the trees. Unlike most other mangrove-dwelling gobies, this l itt le species forms small, hovering schools near the surface of puddles. Congregating in the middle of water bodies provides the obvious benefit of safety in numbers, and helps these gobies avoid cryptic predators like the Finescale Gudgeon (Incara multisquamata) ? a crafty mangrove f ish with an insatiable appetite. Although tiny, Lidwill?s Dwarf Goby is no weakling. Being adapted to life in shallow tide pools means it is physiologically tough, as individuals are regularly subjected to low dissolved oxygen levels, seasonally high water temperatures, f luctuating salinity and acidic water conditions. Two observable adaptations to contend with poor water quality are inactivity and surface gasping (known technically as aquatic surface respiration ? ASR) during low tide. Similar to most other mangrove gobies, Lidwill?s Dwarf Goby is rather drab, with the sparse colouration mostly l imited to a f lash of bright yellow on the posterior rays of the f irst dorsal f in. There is a second similar-looking species of Pandaka goby inhabiting Darwin Harbour, but it is predominantly a freshwater f ish. As these two species may coexist in upstream mangroves, identif ication is often dif f icult without a microscope. That being said, the presence of four small black blotches on the f ish?s posterior end, one large mark on the anal f in, and three smaller ones on the ventral margin of the caudal peduncle (i.e. the narrow part of a body before the tail f in) usually determines the identity of this delightful l itt le f ish. Bit s N' Pieces References: Akihito, P. & Meguro, K. (1975).Pandaka trimaculata, a new species of dwarf goby from Okinawa Prefecture, Japan and the Philippines. Japanese Journal of Ichthyology 22(2): pp. 63-67. Larson, H.K., Will iams, R.S. & Hammer, M.P. (2013). An annotated checklist of the f ishes of the Northern Territory, Australia.Zootaxa 3696: pp. 1-293. At only 12 mm long, Lidwill?s Dwarf Goby is one of the smallest gobies on the planet.