Morphometric and physical characteristics distinguishing adult Patagonian lamprey, Geotria macrostoma from the pouched lamprey, Geotria australis

The pouched lamprey, Geotria australis Gray, 1851, has long been considered monotypic in the Geotriidae family with a wide southern temperate distribution across Australasia and South America. Recent studies have provided molecular and morphological evidence for a second Geotria species in South America; Geotria macrostoma (Burmeister, 1868). The aim of this study was to determine morphometric and physical characteristics of adult G. macrostoma that further differentiate this re-instated species of Geotriidae from G. australis. The diagnostic features discriminating immature adult G. macrostoma from G. australis when entering fresh water, are distinct differences in dentition, oral papillae and fimbriae counts and differences in coloration. In addition, G. macrostoma display greater growth of the prebranchial region and oral disc and has a deeper body depth and higher condition factor. All current ecological knowledge of the genus Geotria is based on Australasian populations, which may not be applicable to G. macrostoma. To ensure the conservation and protection of the Patagonian lamprey as a re-identified species, further investigations are needed to understand its life history, biology and ecology throughout its range

Developmental alterations in noxious-evoked EEG activity recorded from rat primary somatosensory cortex

Primary somatosensory cortex (S1) contains a nociceptive map that localizes potential tissue damage on the body and encodes stimulus intensity. An objective and specific biomarker of pain however is currently lacking and is urgently required for use in non-verbal clinical populations as well as in the validation of pre-clinical pain models. Here we describe studies to see if the responses of the S1 in juvenile rats are different to those in the adult. We recorded electroencephalogram (EEG) responses from S1 of lightly-anesthetized Sprague–Dawley rats at either postnatal day 21 or postnatal day 40 during the presentation of noxious (55 °C) or innocuous (30 °C) thermal stimuli applied to the plantar surface of the left hindpaw. The total EEG power across the recording period was the same in both ages after stimulation but the frequency distribution was significantly affected by age. Noxious heat evoked a significant increase in theta band (4–8 Hz) activity in adults only (P < 0.0001 compared to baseline; P < 0.0001 compared to juveniles). There were no significant differences in EEG responses to innocuous thermal stimuli. These data show that there are significant alterations in the processing of nociceptive inputs within the maturing cortex and that cortical theta activity is involved only in the adult cortical response to noxious stimulation

Putting the "river" back into the Lower River Murray: quantifying the hydraulic impact of river regulation to guide ecological restoration

The hydraulic characteristics of lotic systems are fundamental to ecological processes and patterns. In the lower River Murray, Australia upstream dams and diversions have altered hydrology, whilst sequential low-level weirs have fragmented and homogenised a once lotic system. In this paper we (1) use modelling and empirical data to quantify changes to riverine hydraulics (i.e. river level and water velocities) since regulation, (2) propose that these changes have impacted riverine biota and processes, and (3) present modelled data and discussion on the efficacy of weir lowering and removal to conserve/restore lotic habitats, processes and biota. The weirs have raised river level and reduced river gradient and discharge-water velocity relationships, which when coupled with altered hydrology has resulted in overall declines in water velocities. Under regulated low flows (i.e. 0.3 m s -1) now exist only in the upper reaches of a few weir-pools and anabranches, and are not restored to large reaches of the river until discharge is >/-20,000 ML day -1. We demonstrate that lowering/ removing weirs has the capacity to enhance the area of lotic habitats at discharges <30,000 ML day -1. Whilst weir lowering/ removal has socio-economic implications (e.g. lowering water supply offtakes), we provide the ecological rationale behind such actions and seek to promote discussion of their applicability for restoring a lotic ecosystem.Christopher M. Bice, Matthew S. Gibbs, Nadine N. Kilsby, Martin Mallen-Cooper and Brenton P. Zampatt