Alistar Ian Robertson

University of Western Australia | UWA · School of Biological Sciences

We investigated the forest structure, leaf demography, leaf allometry and growth of the erect canopy of the mangrove palm Nypa fruticans in four river systems distributed over 10 degrees of latitude in the tropics of northeast Australia and Papua New Guinea to obtain estimates of aboveground biomass (AGB) and annual aboveground net primary producti...

Leaf litter consumption has implications for growth and nutrient balances of mangrove crabs and mangrove trophic pathways. This study addressed (1) the impact of leaf litter quality and quantity on crab life history and growth, and (2) proposed keystone roles of crabs in mangrove material fluxes. Estimates of crab standing stocks, growth and carbon...

With a view to learning from the past to help secure a brighter future, this chapter explores some of the deep cultural drivers behind the quite divergent visions or narratives and, to some extent, longstanding but pervasive mythologies about the best way to govern the north of Australia. It explores how these vastly divergent narratives need to be...

The global carbon sequestration and avoided emissions potentially achieved via blue carbon is high (∼3% of annual global greenhouse gas emissions); however, it is limited by multidisciplinary and interacting uncertainties spanning the social, governance, financial, and technological dimensions. We compiled a transdisciplinary team of experts to elu...

Context. Restored mangrove forests are threatened by the restricted range of species used. Xylocarpus granatum has excellent timber and could add value in mangrove plantings. Methods. Forest structure and environmental variables were measured at 40 sites in northern Australia and Papua New Guinea. Tree growth was measured at 18 sites. Boosted regre...

We investigated how variation in climate influences the timing and intensity of phenological events in two species of the mangrove genus Xylocarpus. Leaf fall in Xylocarpus granatum was continuous in high rainfall sites but was seasonal at sites with long dry seasons. Xylocarpus moluccensis is deciduous, and leaf shedding occurred over 1–2 months a...

We estimated the magnitude and direction of exchanges of POC and DOC between the river and four floodplain wetlands (billabongs) and a 140 km reach of riverbank and floodplain of the Murrumbidgee River during a managed high flow experiment. Billabongs were connected to the river channel for between five and 12 days by the flow pulse. There was a ne...

Dead fine roots are the major component of organic carbon (C) stored in mangrove forests. We measured the mass and decomposition of fine root detritus in three mangrove forests along an intertidal gradient in tropical Australia to provide the first integrated estimates of the rate of turnover of fine root detritus. The grand mean dry masses of dead...

Australia represents a global proving ground for effective riparian climate change adaptation due to its scale and diversity, extreme variation in runoff and degrees of aridity. An array of autonomous riparian zone (RZ) management adaptations have emerged in Australia that have captivated the international community but have yet to be effectively d...

There is much discussion and debate within the Australian community, government, the media and academia about the future development and potential of northern Australia. Foreign and Australian agriculturalists are looking to the nation's north with a weather-eye on food security and new economic opportunities. Mineral and energy exploration and dev...

This volume provides a state-of-the-art summary of biogeochemical dynamics at major river-coastal interfaces for advanced students and researchers. River systems play an important role (via the carbon cycle) in the natural self-regulation of Earth's surface conditions by serving as a major sink for anthropogenic CO2. Approximately 90 percent of glo...

Most of the world’s water and sediment is discharged from tropical rivers, making the tropical coastal ocean the major conduit for exchange of dissolved and particulate elements and gases between land, sea, and atmosphere. Tropical oceanic fluxes of dissolved C, N, and P range from 65 to80% and from 65 to70% for particulate C, N, and P, of total gl...

1. The biological productivity of floodplain rivers is intimately related to their flow regimes and it has been proposed that fish production should be linked to components of the flow regime in productivity models. To assess applicability of existing models of productivity in floodplain rivers, we tested predictions about growth during the early l...

Flow and sediment regimes of floodplain rivers around the world have been changed by river regulation and land management, altering the ecological processes structuring riparian plant communities. However, the combined effects of inundation and sedimentation processes on riparian plant survival and growth are poorly understood. The separate and int...

Abstract – To aid otolith interpretation of wild fish, we conducted a laboratory study using metalarval Australian smelt (Retropinna semoni) collected from the Murray River, to examine daily increment deposition and the effects of different temperatures and feeding regimes on otolith growth. Daily increment deposition was confirmed by comparing the...

We investigated changes in the spatial organization of individuals within a population of endangered Southern Bell Frogs Litoria raniformis over an eight-month period. Our results identified strong temporal changes in both spatial organization and the apparent location of L. raniformis within the study site. Ripley's K Function analyses showed that...

Riparian habitats are where terrestrial and aquatic ecosystems meet. They are vital sites in a catchment supporting high levels of biodiversity. Given the large number of rivers in Tasmania and, in some places, their level of degradation, there is a need for a rapid method of measuring riparian condition to underpin strategies for improved manageme...

Summary To a large extent, the condition of riparian areas in Australia is determined by the management actions of private landholders. In this study, we discuss findings from our research in the Goulburn Broken Catchment comparing landholder and scientist assessments of the condition of riparian areas. We interviewed 33 landholders and undertook e...

Riparian habitats are where terrestrial and aquatic ecosystems meet. They are vital sites in a catchment supporting high levels of biodiversity. This is true even for riparian areas adjacent to creeks and gullies that may flow with water only occasionally. Given the extensive degradation of riparian zones in Australia, there is a need for a rapid m...

Riparian habitats are where terrestrial and aquatic ecosystems meet. They are vital sites in a catchment supporting high levels of biodiversity. ~ Given the extensive degradation of riparian zones in Australia, there is a need for a rapid method of measuring riparian condition to underpin strategies for improved management. ~ Riparian condition ref...

The ecological condition of riparian habitats and the biodiversity of terrestrial birds, wetland frogs and herbaceous plants were surveyed in river red gum habitats on the Murrumbidgee and Murray Rivers. Sites were classified according to the intensity of grazing by domestic livestock: ungrazed; low grazing (<5 DSE/ha/annum); and high grazing (>5 D...

Nutrient-use efficiency (NUE) within forests of the mangroves Rhizophora stylosa and Avicennia marina was estimated in arid Western Australia using litter fall rates and rates of leaf CO2 exchange. Litter fall rates ranged from 9.8 to 34.4 t DW ha−1 y−1 but equated to only 13–41% (mean = 30%) of net canopy primary production. Foliar N:P ratios were...

Satellite imagery has been used in many studies that seek to relate river flow to floodplain inundation. However, on rivers with moderately to highly variable daily flows it is difficult to establish a reliable relationship between river stage and area of floodplain inundation. This is because the rapid downstream movement of the flood peak results...

Riparian habitats support high levels of biodiversity and perform essential ecological functions. Management practices adopted by private landholders, such as the grazing of domestic livestock, can influence the condition of riparian habitats. In this project, we interviewed thirty-three landholders and undertook ecological condition assessments at...

1. This report presents the findings of a field project undertaken in the west and south Gippsland region of Victoria between May and December 2002. The specific aims of this project were (1) to determine the current condition of riparian habitats across the west and south Gippsland dairy region, (2) to investigate the relationships between landhol...

In this paper we present a simple in expensive substrate for studying biofilms. Bioballs are robust plastic spheres with high surface area to volume ratios (ca 130:1) used in home aquarium filters. Their properties make them ideal substrates for use in studies of aquatic biofilms. As examples, in this paper we describe the growth and enzyme activit...

Summary In this paper we discuss the findings of research exploring landholder adoption of practices expected to improve the management of river frontages. This research was part of a larger project undertaken by the Goulburn Broken Catchment Management Authority (GBCMA) to assess the impacts of grazing on the condition of riparian zones in the GBC...

Floods are a frequent but irregular feature of Australia's dryland river catchments. We investigated changes in abundances of waterbirds in north western New South Wales with changes in wetland distribution at local, catchment and broad scales. The abundance of most functional groups of waterbirds changed in response to broad scale changes in wetla...

Rates of seed predation are influenced by conditions that alter seed supply and the activity of seed predators. In southern Australia the potential seed supply for the dominant floodplain tree species, the river red gum Eucalyptus camaldulensis , has been reduced through forest clearing to support grazing by introduced livestock. River regulation a...

Riparian areas provide vital habitat for bird species. Since it’s settlement 150 years ago, the Murrumbidgee Catchment in south-eastern Australia has suffered extensive clearing and the effects of grazing practices. The introduction of non-native livestock to riverine areas has resulted in severe reduction in riparian habitat quality because livest...

River regulation and abstraction have dramatically altered the natural flow regime of many rivers world‐wide, but experimental investigations of the biological effects are infrequent. In the mid‐region of the Murray River, Australia, river regulation has reduced the frequency and duration of spring floods and increased the frequency of summer flood...

Grazing by introduced ungulate livestock is a major form of land use over large parts of Australia. Due to the tendency of stock to concentrate around water, riparian zones and wetlands are heavily impacted by grazing. However, little is known about how effects on riparian habitats vary spatially and with management regimes. We investigated how liv...

There is growing awareness that patterns of habitat use by animals cannot be isolated from issues of scale. Recently, techniques have been devised which allow empirical testing of hypotheses related to the effects of spatial scale on habitat use. We used spatially explicit statistical procedures to examine the roles of scale and habitat arrangement...

Bird communities are declining in south-eastern Australia and riparian woodlands are critical habitats for birds in this agricultural region. We investigated how terrestrial bird communities varied with different land management practices (levels of grazing by domestic livestock and extent of clearing) and with habitat quality on the floodplains of...

Arid Australia supports extraordinary numbers of waterbirds. We show that the solution to this seeming paradox lies in considering the availability of temporary wetland habitat in the context of the birds dispersal capability and fluctuations in the abundance of wetlands in time and space. For species with large dispersal capabilities, the Lake Eyr...

The distribution and area of temporary wetlands across the arid zone of Australia are highly variable. Any change in their distribution or extent due to climate change and/or extraction of water has the potential to adversely impact dependent biota. Satellite imagery was used to determine the spatial and temporal distribution of wetlands across ari...

n this paper we discuss the findings of a mail survey that was part of a larger research project undertaken by the Goulburn Broken Catchment Management Authority (GBCMA) and funded by Land and Water Australia to assess the impacts of grazing on the condition of riparian zones. The mail survey explored landholder adoption of practices expected to im...

1. We determined the rate of release and microbial uptake of dissolved organic carbon (DOC) leached from three components (leaves, bark and twigs) of river red gum ( Eucalyptus camaldulensis ) forest litter originating from different parts of a floodplain and under different oxygen levels. 2. Preliminary experiments showed that substantially more...

Vegetation structure and composition and the mass of components of organic detritus were assessed in paired areas, with and without stock access, at six sites. The study revealed that grazing has altered and continues to alter the structure and function of the riparian landscape in the Murrumbidgee River and its tributaries in southeastern Australi...

Comparisons of litter standing-stocks in low-lying and higher areas of the floodplain and the effects of controlled flooding events on leaf litter decomposition and leaf litter nutrients were examined during autumn and winter in a southeastern Australian river red gum (Eucalyptus camaldulensis) floodplain forest. The mean mass of total litter and s...

Comparisons of litter standing-stocks in low-lying and higher areas of the floodplain and the effects of controlled flooding events on leaf litter decomposition and leaf litter nutrients were examined during autumn and winter in a southeastern Australian river red gum (Eucalyptus camaldulensis) floodplain forest. The mean mass of total litter and s...

This paper reviews research on fluxes of carbon in Australian floodplain rivers. Except where cover is absent, and in-stream gross primary production is >1 gC m(-2) day(-1) and ratios of production to respiration are >1, riparian sources dominate carbon pools in catchment streams. On floodplains, primary production by river red gum (Eucalyptus cama...

This paper reviews studies of relationships between riverine fish and woody debris at micro- and meso-habitat scales, and discusses the potential functions of instream structure for lowland river fish. Experimental research, mainly in North America, has identified three main functions of woody debris as microhabitat for fish in upland streams: over...

The National Eutrophication Management Program (NEMP), funded by the Land and Water Resources Research and Development Corporation and the Murray–Darling Basin Commission, supported a workshop in Wagga Wagga in November 1997 to review the current state of knowledge regarding the relative importance of different nutrients and variations in the light...

The high costs and lengthy time commitments associated with traditional monitoring, and the remoteness of many wetlands have necessitated the development of techniques for rapid wetland appraisal. A rapid appraisal condition index based on four attributes of wetlands, soil, fringing vegetation, aquatic vegetation and water quality, was developed fo...

While farms are the basic management unit in dryland farming systems, ecological processes, which control the structure and function of resources, act over a variety of space and time scales and are influenced by social and economic factors outside farm boundaries. Sustainable resource use thus requires management of complete agroecosystems. A shif...

There has been very little published about evaluations of natural resource management programs in Australia. This situation reduces information transfer between program managers and evaluators and increases the likelihood that past mistakes will be repeated. In this paper the authors reflect upon their recent experience with evaluations of the Murr...

The influence of river discharge on the behaviour of dissolved and particulate nutrients, and patterns of primary and bacterial production, were investigated in the Gulf of Papua, northern Coral Sea. Inshore, close to the mouths of the Fly and Purari Rivers, buoyant plumes of warmer river water, marked by high total suspended solid concentrations a...

The role of agriculture and its impact on Australia's relatively fragile environment is a continuing source of unresolved concern. In the past, agricultural producers and the environmental movement have adopted polarised views on how the Australian landscape should be managed. Some environmentalists have perceived primary producers as exploiters of...

Grazing by domestic livestock has a major impact on wetlands in Australia. This paper describes the effects, sources of variance in the effects, relationships with other factors and the management of livestock in and around wetlands.

Abstract A study of frog species richness and abundance at four permanent billabongs located in and around the city of Wagga Wagga, southern New South Wales, was carried out from the spring of 1991 to the autumn of 1992. During the sampling period a total of 404 individual adult frogs from six species were recorded. No egg masses or tadpoles were d...

Selected physical, chemical, and biological characteristics of soils in mechanically damaged North Queensland mangrove forests were examined and compared with undisturbed controls. Soils in nine forests were tested in a factorial sampling programme designed to examine effects of (i) severity of mechanical damage to forests (severely damaged: trees...

Two billabongs on the floodplain of the Murrumbidgee River, Australia, were partitioned in half with impermeable plastic barriers for four months from summer to winter 1995. The densities of carp were manipulated to establish high-and low-carp biomass treatments in each billabong. Final standing stocks of carp in the high-and low-carp treatments of...

Two billabongs on the floodplain of the Murrumbidgee River, Australia, were partitioned in half with impermeable plastic barriers and the biomass of carp was manipulated to establish high- and low-carp biomass treatments in each billabong. Measurements of benthic variables (rates of particle settlement, biofilm development, sediment respiration, ma...

A preliminary mass balance for organic carbon in the Fly Delta was constructed to determine the quantity and source of organic matter exported to the adjacent Gulf of Papua and Coral Sea. Total organic carbon input from the river to the delta is 1.7 1012 g C yr–1, composed almost equally of DOC and POC. Benthic and pelagic respiration in the delta...

Benthic food chains of the Amazon (Brazil) and Fly (Papua New Guinea) river deltas and adjacent shelves are compared. Abundance patterns of the major trophic groups (bacteria, meiofauna, and macroinfauna) are similar between regions, with very low densities, or the absence of benthos, within and near the deltas. For muds in the more quiescent areas...

Preliminary estimates of the ratio of mangrove forest: shrimp pond area necessary to remove nutrients from shrimp pond effluent are made using budgets of nitrogen and phosphorus output for semi-intensive and intensive shrimp ponds combined with estimates of total net primary production in Rhizophora-dominated mangrove forests in tropical coastal ar...

Separation of live and dead fine roots is a critical process in studies of fine root dynamics, but many studies use subjective visual cues during time-consuming hand sorting of root samples, or do not attempt separation at all. Here we describe a method for separating fine roots from mangrove forests using solutions of colloidal silica. The method...

We measured planktonic processes (primary and bacterial production, respiration) and concentrations of suspended material, nutrients, chlorophyll a, floating macroparticulate matter, zooplankton and neuston in the delta and river plume of the Fly River in Papua New Guinea in July/August 1989 and February 1990. There appeared to be conservative mixi...

Separation of live and dead fine roots is a critical process in studies of fine root dynamics, but many studies use subjective visual cues during time-consuming hand sorting of root samples, or do not attempt separation at all. Here we describe a method for separating fine roots from mangrove forests using solutions of colloidal silica. The method...

Patches within a mixed bed of the seagrasses Amphibolis antarctica and Amphibolis griffithii were manipulated in three ways: by the removal of epiphytes, by the removal of leaves, and by altering seagrass density. 1 month after the manipulation, large differences remained between the faunas inhabiting the variously treated patches. Leaf removal and...

Large volumes of freshwater and suspended material debouch from the Fly River in southwestern Papua New Guinea into the Gulf of Papua, greatly influencing the hydrography and sedimentary processes within the river delta and adjacent shelf region. Sedimentary facies within the subtidal regions of the Fly Delta are composed mainly of compacted and er...

Insect herbivores remove up to 35% of leaf area from some mangrove tree species and can cause the death of seedlings. Leaf chemistry and toughnesss and soil nutrient status all appear to be important in explaining the between- and among-species variance in leaf damage. Insects also attack and damage, mainly by boring, a large proportion of mangrove...

In April, July and August 1989 and February 1990, the delta region of the Fly River was surveyed to establish the aerial extent of mangrove forests, their species composition, tree densities and basal areas, and potential net primary production. Mangrove forests cover 87 400 ha, mainly on islands within the delta. Twentynine mangrove plant species...

We examined the vertical profiles of disolved and particulate copper concentrations in the sediments within this region to determine whether any metal pollution has yet occurred as a result of the Ok Tedi mining operation, and to evaluate the spatial extent of copper levels in relation to sediment organic content, grain size and nutrient chemistry

Twenty fish species accounted for > 96% of the catch by numbers in mangrove habitats in Alligator Creek, in tropical Queensland, Australia. The timing of recruitment, residency status, the period of residence and growth of fish during the time they spent in the mangrove habitat was assessed by examining gonad maturity and following changes in size-...

The epibenthos inhabiting creek-bottoms in a tidally influenced mangrove forest, a mangrove-lined estuary and several sites in two open embayments, was sampled on four occasions between August 1986 and June 1987. The inshore (mangrove habitats)-offshore (embayment) patterns in total faunal taxonomic richness (means ranging from 0 to 32·5 taxa per t...

Various components (sediments, algal mats, decomposing logs and algal-covered prop roots) of a tropical mangrove forest showed low to moderate nitrogen fixation (acetylene reduction) rates. Measurements carried out in March, May and October 1989 revealed negligible or inconsistent seasonal variation in activity for all components. Prop roots with t...

Regular daylight sampling over 13 mo (February 1985-February 1986) in and adjacent to intertidal forested areas, in small creeks and over accreting mudbanks in the mainstream of a small mangrove-lined estuary in tropical northeastern Queensland, Australia, yielded 112 481 fish from 128 species and 43 families. Species of the families Engraulidae, A...

Although insects are known to be important seed predators in most terrestrial forests, their role in marine tidal (mangrove) forests has not been examined. Surveys at 12 sites in tropical Australia showed that between 3.1 and 92.7 percent of the seeds or propagules of 12 mangrove tree species had been attacked by insects. Seeds/propagules of six sp...

In Missionary Bay on Hinchinbrook Island in tropical northeastern Australia, there is one of the largest mangrove forests in the region (50 km2). Annual input of mangrove litter (leaves. stipules and reprotluctive parts) from these forests into the bay was estimated to be 12593 tonnes Carbon. Surveys of the quantity of mangrove detritus on the bott...

Single exponential decay models fitted to dry mass and carbon decomposition data for tree trunks in mixed Rhizophora mangrove forests in tropical Australia had decay constants of 0.083 and 0.108 yr-1 respectively. Decay of twigs and small branches was more rapid with decay constants of 0.276 (dry mass) and 0.310 yr-1 (carbon). Aboveground standing...

Measurements of litter fall and litter removal by crabs, in conjunction with estimates of litter decay by microbes and tidal export of litter from three high-intertidal mangrove forests were made during a year-long study in tropical northeastern Australia. In forests dominated by Ceriops tagal and Bruguiera exaristata, litter standing stocks remain...