Independent and conjugate eye movements during optokinesis in teleost fish

In response to movements involving a large part of the visual field, the eyes of vertebrates typically show an optokinetic nystagmus, a response in which both eyes are tightly yoked. Using a comparative approach, this study sets out to establish whether fish with independent spontaneous eye movements show independent optokinetic nystagmus in each eye. Two fish with independent spontaneous eye movements, the pipefish Corythoichthyes intestinalis and the sandlance Limnichthyes fasciatus were compared with the butterflyfish Chaetodon rainfordi, which exhibits tightly yoked eye movements. In the butterflyfish a single whole-field stimulus elicits conjugate optokinesis, whereas the sandlance and pipefish show asynchronous optokinetic movements. In a split drum experiment, when both eyes were stimulated in opposite directions with different speeds, both the sandlance and the pipefish compensated independently with each eye. The optokinetic response in the butterflyfish showed some disconjugacy but was generally confused. When one eye was occluded, the seeing eye was capable of driving the occluded eye in both the butterflyfish and the pipefish but not in the sandlance. Monocular occlusion therefore unmasks a link between the two eyes in the pipefish, which is overridden when both eyes receive visual input. The sandlance never showed any correlation between the eyes during optokinesis in all stimulus conditions. This suggests that there are different levels of linkage between the two eyes in the oculomotor system of teleosts, depending on the visual input.

Adaptation of rainbow fish to lake and stream habitats

Fish occupy a range of hydrological habitats that exert different demands on locomotor performance. We examined replicate natural populations of the rainbow fishes Melanotaenia eachamensis and M. duboulayi to determine if colonization of low-velocity (lake) habitats by fish from high-velocity (stream) habitats resulted in adaptation of locomotor morphology and performance. Relative to stream conspecifics, lake fish had more posteriorly positioned first dorsal and pelvic fins, and shorter second dorsal fin bases. Habitat dimorphism observed between wild-caught fish was determined to be heritable as it was retained in M. eachamensis offspring raised in a common garden. Repeated evolution of the same heritable phenotype in independently derived populations indicated body shape divergence was a consequence of natural selection. Morphological divergence between hydrological habitats did not support a priori expectations of deeper bodies and caudal peduncles in lake fish. However, observed divergence in fin positioning was consistent with a family-wide association between habitat and morphology, and with empirical studies on other fish species. As predicted, decreased demand for sustained swimming in takes resulted in a reduction in caudal red muscle area of lake fish relative to their stream counterparts. Melanotaenia duboulayi lake fish also had slower sustained swimming speeds (U-crit) than stream conspecifics. In M. eachamensis, habitat affected U-crit of males and females differently. Specifically, females exhibited the pattern observed in M. duboulayi (lake fish had faster U-crit than stream fish), but the opposite association was observed in males (stream males had slower Ucrit than lake males). Stream M. eachamensis also exhibited a reversed pattern of sexual dimorphism in U-crit (males slower than females) relative to all other groups (males faster than females). We suggest that M. eachamensis males from streams responded to factors other than water velocity. Although replication of muscle and U,,it phenotypes across same habitat populations within and/or among species was suggestive of adaptation, the common garden experiment did not confirm a genetic basis to these associations. Kinematic studies should consider the effect of the position and base length of dorsal fins.

Behavioural responses of two native Australian fish species (Melanotaenia duboulayi and Pseudomugil signifer) to introduced poeciliids (Gambusia holbrooki and Xiphophorus helleri) in controlled conditions

Experimental treatments to compare behavioural responses included native fish species only, natives plus one exotic species and natives plus both exotic species. The mosquitofish, Gambusia holbrooki frequently attacked both native species, but tended to nip Melanotaenia duboulayi (especially small individuals) and chase Pseudomugil signifer The frequency of attacks by G. holbrooki on M. duboulayi rose when all four fish species were present. When food was added, all four species showed a strong increase in aggression, especially in the four-species treatment, where there were significant increases in the frequency of attacks by the swordtail Xiphophorus helleri on M. duboulay and by M. duboulayi on G. holbrooki, and of conspecific attacks by M. duboulayi. Increased attack frequency was associated with aggregation closer to the water's surface, regardless of the presence of food. The results support the hypothesis that introduced poeciliids can have deleterious competitive effects on native species. However, while juvenile M. duboulayi were particularly vulnerable to the secondary, effects of fin-nipping, R signifer appeared to be more susceptible to physical displacement and reduced food capture success.

Cleaner fish drives local fish diversity on coral reefs

Coral reefs are one of the most diverse habitats in the world [1], yet our understanding of the processes affecting their biodiversity is limited [1-3]. At the local scale, cleaner fish are thought to have a disproportionate effect, in relation to their abundance and size, on the activity of many other fish species, but confirmation of this species' effect on local fish diversity has proved elusive. The cleaner fish Labroides dimidiatus has major effects on fish activity patterns [4] and may indirectly affect fish demography through the removal of large numbers of parasites [5, 6]. Here we show that small reefs where L. dimidiatus had been experimentally excluded for 18 months had half the species diversity of fish and one-fourth the abundance of individuals. Only fish that move among reefs, however, were affected. These fish include large species that themselves can affect other reef organisms [2, 7]. In contrast, the distribution of resident fish was not affected by cleaner fish. Thus, many fish appear to choose reefs based on the presence of cleaner fish. Our findings indicate that a single small [8] and not very abundant [9] fish has a strong influence on the movement patterns, habitat choice, activity, and local diversity and abundance of a wide variety of reef fish species.

Competition and resource availability in an annual plant community dominated by an invasive species, Carrichtera annua (L. Aschers.), in South Australia

The last decade has seen spirited debates about how resource availability affect the intensity of competition. This paper examines the effect that a dominant introduced species, Carrichtera annua, has upon the winter annual community in the arid chenopod shrublands of South Australia. Manipulative field experiments were conducted to assess plant community response to changing below-ground resource levels and to the manipulation of the density of C. annua. Changes in the density of C. annua had little effect on the abundance of all other species in the guild. Nutrient addition produced an increase in the biomass of the most abundant native species, Crassula colorata. An analysis of the root distribution of the main species suggested that the areas of soil resource capture of C. annua and C. colorata are largely segregated. Our results suggest that intraspecific competition may be stronger than interspecific competition, controlling the species responses to increased resource availability. The results are consistent with a two-phase resource dynamics systems, with pulses of high resource availability triggering growth, followed by pulses of stress. Smaller plants were nutrient limited under natural field conditions, suggesting that stress experienced during long interpulse phases may override competitive effects after short pulse phases. The observed differences in root system structure will determine when plants of a different species are experiencing a pulse or an interpulse phase. We suggest that the limitations to plant recruitment and growth are the product of a complex interplay between the length and intensity of the pulse of resource availability, the duration and severity of the interpulse periods, and biological characters of the species.

Locomotion at-1.0 degrees C: burst swimming performance of five species of Antarctic fish

We investigated the burst swimming performance of five species of Antarctic fish at -1.0degreesC. The species studied belonged to the suborder, Notothenioidei, and from the families, Nototheniidae and Bathydraconidae. Swimming performance of the fish was assessed over the initial 300 ms of a startle response using surgically attached miniature accelerometers. Escape responses in all fish consisted of a C-type fast start; consisting of an initial pronounced bending of the body into a C-shape, followed by one or more complete tail-beats and an un-powered glide. We found significant differences in the swimming performance of the five species of fish examined, with average maximum swimming velocities (U-max) ranging from 0.91 to 1.39 m s(-1) and maximum accelerations (A(max)) ranging from 10.6 to 15.6 m s(-2). The cryopelagic species, Pagothenia borchgrevinki, produced the fastest escape response, reaching a U-max and A(max) of 1.39 m s(-1) and 15.6 m s(-2), respectively. We also compared the body shapes of each fish species with their measures of maximum burst performance. The dragonfish, Gymnodraco acuticeps, from the family Bathdraconidae, did not conform to the pattern observed for the other four fish species belonging to the family Nototheniidae. However, we found a negative relationship between buoyancy of the fish species and burst swimming performance. (C) 2002 Elsevier Science Ltd. All rights reserved.

Microhabitat use by the rainbowfish Melanotaenia duboulayi in a subtropical Australian stream

Microhabitat use and feeding behavior of the rainbowfish Melanotaenia duboulayi (Castelnau) were investigated in a slow-flowing stream adjacent to riparian forest in south-eastern Queensland, Australia. Fish were more abundant in vegetated areas, but did not enter dense Vallisneria beds, where predators were observed. In sunny conditions shoals of juveniles occurred near the water surface feeding floating material on the surface, but larger fish tended to occur at the bottom near submerged vegetation, often utilizing the overhanging aquatic plant community as a refuge and food source. In the middle of the day, juveniles and small fish seemed to show behavioral thermoregulation at the surface in the warmest site. Under cloudy conditions, however, fish of all sizes preferred deeper water. The present study suggests that in still and sunny pools thermal change caused by sunlight influences the microhabitat choice of small fish. A field experiment using a kingfisher model implies that fish swimming at the surface could escape from aerial predators in sunlit conditions by responding to moving shadows, but could not do so under cloudy conditions.

An evaluation of a family psychoeducation program in community mental health

The aim of the research project was to identify the efficacy of the family psychoeducation program as a strategy for reducing the hospital admissions of young people. It also aimed to determine if the family psychoeducation program had an impact on the experience of caregiving and knowledge and satisfaction of services provided by the mental health service. A retrospective chart audit compared readmission history of 27 clients whose families attended a psychoeducation program with readmission history of a matched group of young people whose families did not attend the program. A telephone survey was conducted for both groups of families to investigate knowledge and understanding of services and burden of care. The results indicated that family participation in a brief multiple family psychoeducation program did not reduce the number or duration of admissions of the young people. There was no impact on the level of care for families who attended the psychoeducation program, however, this group showed some evidence of increased knowledge and understanding of services as compared to the control group.

Allopodocotyle skoliorchis n. sp. (Opecoelidae: Plagiorporinae) from Parequula melbournensis (Castelnau) (Gerreidae), a temperate marine fish in Australian waters

A new species of Allopodocotyle Pritchard, 1966 is described from the intestine and pyloric caeca of Parequula melbournensis (Gerreidae) caught from the waters off South and Western Australia. The new species is distinguished from other species by its larger eggs, broader form, pre-bifurcal genital pore and a number of other measurable features that are discussed. Of the species that share morphological similarities with Allopodocotyle skoliorchis n. sp., it is the only species known from a gerreid; all the other species are from serranids.

A new species of Podocotyloides Yamaguti, 1934 (Digenea: Opecoelidae) from a Western Australian temperate marine fish

A new species of Podocotyloides is described from Sillago bassensis caught off the coast of Western Australia. This is the second report of a species of this genus from Australian waters but the first of a new species. P. victori n. sp. is one of four species whose vitelline follicles extend into the forebody. It is distinguished from the other three species with vitelline follicles in the forebody by its relatively shorter forebody, smaller eggs and bipartite seminal vesicle. Pedunculotrema Fischthal & Thomas, 1970 is reduced to synonymy with Podocotyloides Yamaguti, 1934.

Candidatus "Scalindua brodae", spec. nov., Candidatus "Scalindua wagneri", spec. nov., two new species of anaerobic ammonium oxidizing bacteria

Anaerobic ammonium oxidation (anammox) is both a promising process in wastewater treatment and a long overlooked microbial physiology that can contribute significantly to biological nitrogen cycling in the world's oceans. Anammox is mediated by a monophyletic group of bacteria that branches deeply in the Planctomycetales. Here we describe a new genus and species of anaerobic ammonium oxidizing planctomycetes, discovered in a wastewater treatment plant (wwtp) treating landfill leachate in Pitsea, UK. The biomass from this wwtp showed high anammox activity (5.0 +/- 0.5 nmol/mg protein/min) and produced hydrazine from hydroxylamine, one of the unique features of anammox bacteria. Eight new planctomycete 16S rRNA gene sequences were present in the 16S rRNA gene clone library generated from the biomass. Four of these were affiliated to known anammox 16S rRNA gene sequences, but branched much closer to the root of the planctomycete line of descent. Fluorescence in situ hybridization (FISH) with oligonucleotide probes specific for these new sequences showed that two species (belonging to the same genus) together made up > 99% of the planctomycete population which constituted 20% of the total microbial community. The identification of these organisms as typical anammox bacteria was confirmed with electron microscopy and lipid analysis. The new species, provisionally named Candidatus Scalindua brodae and Scalindua wagneri considerably extend the biodiversity of the anammox lineage on the 16S rRNA gene level, but otherwise resemble known anammox bacteria. Simultaneously, another new species of the same genus, Candidatus Scalindua sorokinii, was detected in the water column of the Black Sea, making this genus the most widespread of all anammox bacteria described so far.

At-risk children: A demographic analysis of the children of clients attending mental health community clinics

Children of parents with mental illness have an increased risk of psychological problems. The aim of this study was to identify the demographic characteristics of dependent children of adults presenting at mental health clinics in Western Australia. A survey of clients who attended the clinics indicated that half reported having had children. Of these, 21% had a primary diagnosis of schizophrenia. Although schizophrenia was the most common illness, there were almost seven times more children living with a parent with a primary diagnosis of depression than schizophrenia. Recommendations include that children of clients with mental illness be included as part of a wider client focus.

An evaluation of participatory planning at Mapoon Aboriginal community: Opportunities for inclusive local governance

The Queensland Government is increasingly using participatory planning as a means to improve infrastructure and service delivery to Indigenous settlements. In addition to technical and economic goals, participatory planning practice seeks also to achieve social development goals, including empowerment, capacity building, community control and ownership. This article presents the findings of an evaluation of one such planning project, conducted at Old Mapoon in 1995. Despite various efforts to follow participatory processes, the plan had mixed success in achieving social development goals. This suggests some misunderstandings between the practice of participatory planning and the workings of local governance. It also presents some opportunities for participatory planning methods to be integrated with more inclusive forms of governance.