Larval description of the sympatric species, Craterocephalus stercusmuscarum stercusmuscarum(Pisces: Atherinidae) and Mogurnda adspersa(Pisces: Eleotridae) from tropical streams of north‐east Queensland, Australia

Abstract

Descriptions and illustrations of stages in the larval development of two common sympatric freshwater fishes in streams of tropical north-east Queensland, the fly-specked hardyhead Craterocephalus stercusmuscarum stercusmuscarum and the purple-spotted gudgeon Mogurnda adspersa are presented. Larval development is described in terms of ontogenetic changes in gross morphology, notochord morphology, pigmentation, finfold morphology and fin structure. Developmental changes during the larval period of C. s. stercusmuscarum are similar to other atheriniformes, especially the genus Melanotaenia. The highly variable development and advanced state at hatching of M. adspersa in tropical streams contrasts with larval development of disjunct populations of the same species in southern Australia and also with other closely related species of the Eleotridae described elsewhere. Larvae of M. adspersa can be distinguished from C. s. stercusmuscarum on the basis of six key characters: pigmentation, presence of a pre-anal ventral finfold, general body form and shape, number of post-anal myomeres, notochord morphology at hatching and timing of swimbladder inflation. Characters that allow for the accurate discrimination between both of these species and other sympatric atheriniformes are identified. # 2005 The Fisheries Society of the British Isles

Predictable hydrology, habitat and food resources determine fish recruitment dynamics in an incised tropical Australian river

“…This habitat association may be driven by the physical properties and retention capacity of slackwater areas (‘Inshore Retention Concept’—Schiemer et al, 2001) and elevated food abundances (King et al, 2013). The early post‐hatch stages of species found in slack waters of the Mulgrave River, including P. signifier , M. splendida and M. adspersa , hatch with limited fin development (Close et al, 2005; Humphrey et al, 2003; Semple, 1986) and appear to be poorly adapted to withstand the >0.1 ms −1 velocities (see Pusey et al, 2002) measured in the river. DistLM models identified inconsistent patterns between species in their relationships with zooplankton density (i.e., strong for P. signifier but weak for M. splendida ), suggesting that zooplankton availability is not limiting and that other factors influence habitat use.…”

Can backcalculation models unravel complex larval growth histories in a tropical freshwater fish?

“…The wild diet of larval M. adspersa is likely to comprise microinvertebrates based on larval morphology (Close et al ., ) and diet of the juvenile and adult phases (Allen et al ., ; Pusey et al ., ). Therefore, food items in this study were probably a fair proxy for the wild diet; however, the feeding rate of larvae in this study (twice per day) is probably unrealistic in that wild larvae are unlikely to feed to satiation twice a day.…”

“…The exception was the TVG model, where developmental stages of larval M. adspersa were defined at 10 and 15 dph, as described in Close et al . (). Goodness of fit was examined by fitting observed L T against backcalculated L T using linear mixed effects models in R (function lmer in lme4 package) as suggested by Wilson et al .…”