Microphis leiaspis, Bleeker, 1854

Ebner, Brendan C., Maeda, Ken, Donaldson, JamesA., Harasti, David, Lord, Clara, Haÿ, Vincent, Heffernan, Jason, Starrs, Danswell, Thuesen, Paul, Beatty, Stephen, Boseto, David, Copeland, Lekima K. F., Rashni, Bindiya, Hevalao, Robson S. & Keith, Philippe, 2023, Pebbled places preferred by people and pipefish in a World Heritage protected area, Cybium 47 (4), pp. 401-416 : 404

ECOLOGY OF MICROPHIS LEIASPIS

The prehensile tail present in many members of the Syngnathidae ( Dawson, 1985) is a key adaption leading to their occupation of ecological niches in habitats with strong vertical structural elements such as seagrass, fucoid algae, gorgonian corals, and freshwater macrophytes ( Kuiter, 2000; Teske and Beheregaray, 2009). On the other hand, adult Microphis leiaspis hook and press their tail around small pebbles or rocks, allowing them to maintain or change position, but they do not exhibit a prehensile specialization for grasping vertical structures such as seagrass. This is unsurprising as tropical SSCSs typically experience dynamic flows and high discharge, leading to the absence of aquatic plants and the prevalence of bedrock, boulder, cobble, and pebble benthos. Microphis leiaspis is amphidromous with the adult phase occupying and breeding in lowland reaches of streams ( Ishihara and Tachihara, 2008; Maeda and Tachihara, 2010). It does not appear to be widespread on the Australian continent, and to date is only known from the AWT. Our group of authors have observed adult M. leiaspis in SSCSs throughout the AWT, where they appear to be social and are most commonly found in the larger streams of the Cape Tribulation region (e.g., Hutchison, Cooper, Noah, Thompson, Myall, and Emmagen creeks). We have occasionally observed adult M. leiaspis in the Mossman River and in the SSCS of the central Wet Tropics. For completeness, it is important to note that the presence of estuarine crocodiles in the area, and relevant concerns for researcher safety, make it difficult to fully understand the distribution and habitat associations of cryptic fish species in the region, particularly in the larger rivers ( Ebner et al., 2015). The males and female pipefish mature at 105-125 and 130 mm in standard length, respectively, and females deposit eggs in the brood pouch on the abdomen of the male, where the embryos are incubated until being released as larvae ( Ishihara and Tachihara, 2008). Maeda and Tachihara (2010) gathered M. leiaspis larvae from the drift of SSCSs during nocturnal hours, while Ishihara and Tachihara (2008) suggested that drifting marine algae may be associated with the presence of juvenile M. leiaspis . There is no published quantitative information on the habitat use of the juvenile and adult life history phases of this species.

In the following paragraphs, author initials are sometimes ascribed to specific observations to provide some context for our qualitative observations. Three of the authors (BE, JD, KM) have spent more than 20 hours each observing the behaviour of this species in streams in Australia, the Solomon Islands and Okinawa. However, the limited quantitative data presented here focuses on habitat associations exclusively recorded from three 50-m reaches in each of Oliver and Emmagen creeks in the AWT.