bluuebunny/crossref_metadata_2025 huggingface dataset:
Insect flower visitors, foraging behaviour and their effectiveness as pollinators of Persoonia virgata R. Br. (Proteaceae)
Authors: Wallace Helen M , Maynard Glynn V , Trueman Stephen J
Published: March 2003

Leioproctus species are frequent flower visitors to Proteaceae and have
been inferred as pollinators of many species of Persoonia. This study investigated
frequency of flower visitors, their behaviour and the breeding system of Persoonia
virgata. The two most frequent visitors were the native bees Trigona carbonaria
Smith (Hymenoptera: Apidae) and females of Leioproctus (Cladocerapis) speculiferus
Cockerell (Hymenoptera: Colletidae). These species have different foraging strategies
on the flowers of P. virgata and, on the basis of more frequent stigma contact,
L. speculiferus was found to be the most effective pollinator. Pollination
studies indicated that fruit set of bagged flowers (0.5% and 9.2%)
was significantly less (P < 0.001) than fruit set of control flowers left
open to visitors (24.0% and 48.9%) in two experiments, respectively.
Furthermore, flowers that were bagged and cross‐pollinated set significantly (P
< 0.001) more fruit (43.8%) than flowers that were bagged and self‐pollinated
(6.6%), suggesting partial self‐incompatibility. No significant difference
in fruit set was found between control flowers and cross‐pollinated flowers, indicating
that flower visitors of P. virgata were efficient vectors of cross‐pollen from plant to plant.
Morphology of the antennal sensilla in four Australian spittlebug species (Hemiptera: Cercopidae) with implications for phylogeny
Authors: Liang Ai‐Ping , Fletcher Murray J
Published: March 2003

The antennal sense organs of four Australian spittlebugs, Aufidus trifasciatus
Stål, Euryaulax carnifex (Fabricius), Petyllis deprivata (Walker)
and Tonnoiria tasmaniae Lallemand (Hemiptera: Cercopidae) are described for
the first time, based on scanning electron microscope observations. Four major types
of sense organs were found: one basiconic sensillum and 8–9 coeloconic sensilla
on the expanded flagellar base, and several trichoid sensilla and one campaniform
sensillum on the pedicel. The antennal sensilla found in the four species show very
similar patterns in their shape, distribution and arrangement and this suggests that
the genera Aufidus Stål, Petyllis Kirkaldy and Tonnoiria
Lallemand, all currently placed in the Afrotropical and Oriental tribe Rhinaulacini,
may belong to the Australian tribe Euryaulacini. In addition, the history of the
nomenclature of two Australian species previously assigned to the genus Eoscarta
is reviewed, and the following two resurrected combinations established: Euryaulax
carnifex (Fabricius) comb. rev. and Euryaulax vacuola (Jacobi) comb. rev.
Idioscopus clypealis (Lethierry), a second new leafhopper pest of mango in Australia (Hemiptera: Cicadellidae: Idiocerinae)
Authors: Fletcher Murray J , Dangerfield Paul C
Published: March 2003

The first Australian record of Idioscopus clypealis, a serious pest of mango
in south‐east Asia, is reported following the discovery of the species in northern
Queensland in October 1999. This follows the discovery of I. nitidulus (Walker) on mainland Australia in 1997. Descriptions and illustrations of both species are provided to enable the two species to be distinguished. Notes on the economic importance of the species are provided.
First record of the mite Hirstiella diolii Baker (Prostigmata: Pterygosomatidae) from Australia, with a review of mites found on Australian lizards
Authors: Walter David Evans , Shaw Matthew
Published: March 2003

We report the first occurrence in Australia of an exotic mite parasite of lizards, Hirstiella diolii Baker (Prostigmata, Pterygosomatidae), and its association
with iguanas at the Taronga Zoo in Sydney. We also report on the spread of the exotic
snake mite Ophionyssus natricis (Gervais) to native populations of skinks, provide a key to the mites associated with Australian lizards and review how to distinguish chiggers from pterygosomatid mites.
Effect of food and larval density on survival and growth of early instar greyback canegrub, Dermolepida albohirtum (Waterhouse) (Coleoptera: Scarabaeidae)
Authors: Logan David P , Kettle Catherine G
Published: March 2003

Abstract First‐ and early second‐instar larvae of Dermolepida albohirtum (Coleoptera: Scarabaeidae) survived best and gained most weight on living roots of lawn seedlings, sugarcane or Guinea grass (Panicum maximum var. maximum) when compared with decaying plant material or soil alone. Survival of first‐instar D. albohirtum was not density‐dependent, but survival of older larvae (late first‐instar and early second‐instar) was reduced at high larval density. There was no evidence for larval combat between first instars. First instars kept at high density gained less weight and were slower to develop into second instars compared with first instars kept at low density. When food was limited, survival at high larval densities was reduced. Survival of early instars was high in sugarcane fields, probably reflecting the availability of suitable food. We conclude that food type and supply are critical factors affecting the survival and development of early instar D. albohirtum.
Three new species of Orphninotrichia Mosely (Trichoptera: Hydroptilidae) from Barrington Tops, New South Wales, a distribution extended, and remarks on generic placement
Authors: Wells Alice
Published: March 2003

Abstract Three new species are described in the endemic Australian microcaddisfly genus Orphninotrichia Mosely (Trichoptera: Hydroptilidae: Hydroptilinae), all collected in the Barrington Tops area of north‐eastern New South Wales: Orphninotrichia bilobata sp. n., O. claviculata sp. n. and O. dundungra sp. n. From the same area, Orphninotrichia papillata Wells, described from central Victoria, is newly recorded and noted for the atypical presence of a large gland on the dorsum of the male head. Comments are made on the still unresolved affinities of the genus Orphninotrichia, and a key to males of all species is provided.
Zemiathrips: a new genus of fungus‐feeding phlaeothripine Thysanoptera in Australian leaf‐litter
Authors: Mound Laurence A
Published: March 2003

Abstract A new genus of Thysanoptera, Phlaeothripinae, Zemiathrips, is described for five new species. These thrips are locally abundant in leaf‐litter in Australia, particularly in Eucalyptus litter, and each is presumed to feed on fungal hyphae. Almost all individuals are wingless but, in contrast to many fungus‐feeding Phlaeothripidae, none of the species show any within‐sex polymorphism. Representatives of the genus have been found in all Australian states and territories except the Northern Territory and, despite winged individuals being rare, several of the species are widespread.
Octothrips lygodii sp. n. (Thysanoptera: Thripidae) damaging weedy Lygodium ferns in south‐eastern Asia, with notes on other Thripidae reported from ferns
Authors: Mound Laurence A
Published: March 2003

Abstract Weedy Lygodium ferns have become a serious fire hazard in Florida, introduced from the Old World Tropics. During joint CSIRO/USDA studies on potential biological control agents, a thrips species was found widely in south‐eastern Asia causing severe damage to L. microphyllum. Described here as a new species, Octothrips lygodii, this is the second species of a poorly known genus that has been based on a single damaged male from Papua New Guinea. The genus is redefined, the two species distinguished, and notes given on the range of Thripidae reported from ferns worldwide.
Factors affecting the establishment and dispersal of nymphs of Pristhesancus plagipennis Walker (Hemiptera: Reduviidae) when released onto soybean, cotton and sunflower crops
Authors: Grundy Paul R , Maelzer Derek A
Published: March 2003

Abstract A problem with augmenting predatory bugs through mass release is the logistical difficulty of delivering nymphs onto the foliage of field crops. In this paper we examine postrelease establishment and dispersal of the nymphs of the predatory bug Pristhesancus plagipennis on soybean, cotton and sunflower in an effort to devise an appropriate strategy for field release. The effects of predator stadia and release rates on field establishment and within‐crop‐canopy dispersal after hand release were recorded in soybean, cotton and sunflower. Field establishment improved with the release of more‐developed nymphs, with third instars providing the most appropriate compromise between field hardiness and rearing cost. Increased nymphal density at the point of release had little effect on nymphal dispersal throughout the crop canopy. The patterns of nymphal dispersal observed on the three crops suggest that crop‐canopy architecture may have an effect on the ability of nymphs to spread out postrelease, as nymphs dispersed poorly in cotton and sunflower compared to soybean. To overcome poor dispersal of nymphs after release, a mechanical release method, where nymphs were mixed with vermiculite and delivered onto a target crop through a spinning disk fertiliser spreader, was tested, and provided similar nymph establishment rates and dispersal patterns as releasing nymphs individually by hand. The implications of nymph dispersal and field hardiness in regard to inundative field release techniques are discussed.
Revision of the Australasian genus Orussobaius Benson (Hymenoptera: Symphyta: Orussidae)
Authors: Schmidt Stefan , Vilhelmsen Lars
Published: March 2003

Abstract The Australasian genus Orussobaius Benson is revised. Seven species are recognised: Orussobaius paniculus sp. n. from Papua New Guinea, and six species from Australia: O. badius sp. n., O. caligneus sp. n., O. mesembrinus Benson, O. minutissimus sp. n., O. minutus Benson, and O. wilsoni Benson. Orussobaius normani Rayment (new synonymy) is removed from synonymy with O. wilsoni and treated as a junior synonym of O. minutus instead. With a body length of only 2 mm, O. minutissimus sp. n. is the smallest currently known sawfly species in the world. A key is provided and distribution maps are shown for all species. The genus Orussobaius is redefined on the basis of all species currently included.
Synonymy, distribution and bionomics of the Australian blowfly Onesia accepta (Malloch) (Diptera: Calliphoridae)
Authors: Norris KR
Published: March 2003

Abstract Calliphora clausa Macquart 1848 is a senior synonym of Calliphora accepta Malloch 1927, but recent referral of the species to the genus Onesia Robineau‐Desvoidy 1830 encounters the problem that Onesia clausa Macquart 1848 is preoccupied by Onesia clausa Macquart 1835. The name of this fly therefore becomes Onesia accepta (Malloch) 1927. A brief description is given of the fly and its distribution within Australia. The ecological significance of the fly is discussed.
Colony structure and nest characteristics of European wasps, Vespula germanica (F.) (Hymenoptera: Vespidae), in Victoria, Australia
Authors: Ward Darren , Honan Patrick , Lefoe Greg
Published: March 2003

Abstract European wasps, Vespula germanica, are common across southern and south‐eastern Australia and have a negative impact upon urban areas, primary industries, and natural ecosystems. Aspects of colony structure and nest characteristics are examined for nests located in the ground and collected from urban and rural sites in Victoria during two summer−autumn field seasons (1996 and 2001). On average, nests were located 28 cm beneath the surface (range 5−58 cm). The average number of combs in the nest and the total area of the nests increased from early February to late May. In addition, the proportion of cells used to produce workers and different life stages (larvae, pupae) also varied throughout the season; being consistent with studies from New Zealand. No differences in colony structure or nest character­istics were detected between urban and rural nests.
Association between caste and genotype in the termiteMastotermes darwiniensisFroggatt (Isoptera: Mastotermitidae)
Authors: Goodisman Michael A D , Crozier Ross H
Published: March 2003

AbstractTermite workers and soldiers differ markedly in their morphology and behaviour. We sought evidence for genetic influences on caste determination in the giant northern termite,Mastotermes darwiniensis, by investigating if workers and soldiers from the same colony differed genetically. The genotypes of 795 termites from 11 distinct colonies were assayed at six polymorphic microsatellite loci. We found that the multilocus genotypes of workers and soldiers from 8 of the 11 colonies did not differ significantly. Thus, the majority of the data provided no evidence for a genetic association with caste in workers and soldiers ofM. darwiniensis. However, the genotype frequencies of workers and soldiers from three colonies differed, suggesting that genotype is occasionally associated with caste in this species. The genetic differentiation of castes within these colonies could reflect differences in the propensities of termites with distinct genotypes to develop into particular castes and provide a selective advantage to colonies headed by multiple reproductives.
Host relationships at plant family level inDendrothripsUzel (Thysanoptera: Thripidae: Dendrothripinae) with a new Australian species
Authors: Marullo Rita
Published: March 2003

AbstractThe genusDendrothripsUzel (Thysanoptera: Thripidae, Dendrothripinae) comprises 50 described species from the Old World, including a fourth species from Australia,D. williamsisp. n. For many of these species no host plant has been recorded, but the genera and families of the recorded host plants of 27 species are tabulated. These thrips are mainly associated with trees and shrubs, and the plant families involved come from five of the six subclasses of the Dicotyledonae. SeveralDendrothripsspecies are recorded from Oleaceae and Flacourtiaceae, but none from the major families of tropical trees, Moraceae and Lauraceae.
Natural history and description of Aphiura breviceps Schmitz, a scuttle fly (Diptera: Phoridae) whose larvae prey on the eggs of frogs (Anura: Myobatrachidae) in Western Australia
Authors: Davis Robert A , Disney R Henry L
Published: March 2003

Abstract The eggs of the burrow‐nesting frogs Heleioporus albopunctatus Gray and H. eyrei Gray are predated by the larvae and females of the scuttle fly Aphiura breviceps. The morphology of the female fly and natural history of the species (adult and larva) are described for the first time.
Aggregative oviposition behaviour of Helicoverpa spp. (Lepidoptera: Noctuidae) in contaminated chickpea crops
Authors: Sequeira Richard V , Moore Andrew D
Published: March 2003

Abstract Aggregative egg distribution by Helicoverpa spp. within experimental field plots of chickpea containing various contaminant plant species was documented at different stages of plant growth. More eggs were laid on contaminant faba and wheat plants than on the surrounding chickpea. The level of egg aggregation on faba and wheat plants increased with general crop growth, becoming evident before a significant disparity in growth rates between these species and the surrounding chickpea became apparent. In chickpea plots contaminated with canola, aggregative oviposition activity on the contaminant plants was observed in the early seedling stage whilst a clear height differential between the two species was evident. Total Helicoverpa egg density on contaminant plants was not correlated with height above chickpea for any of the contaminant species. It is proposed that the aggregative oviposition behaviour of Helicoverpa spp. in contaminated chickpea results from differential apparency of the contaminant plants to ovipositing moths. Differential apparency may result from several factors including growth rate and morphological differences between chickpea and the contaminants. Physiological changes in chickpea, including growth stage‐related changes in acid production by the foliage, may also contribute to the greater apparency of contaminant plants in chickpea plots. The implications of differential host plant apparency for insect pest management are discussed.
Recognition of the genusHoplosaenideaLaboissière in Australia, with a key to the Australian genera of Galerucini (Coleoptera: Chrysomelidae: Galerucinae)
Authors: Reid CAM
Published: March 2003

AbstractThe south‐east Asian genusHoplosaenideaLaboissière is recognised in Australia for the first time, with a single species,scutellatasp. n., occurring in north Queensland and New Guinea. A key is provided for identification of the Australian genera of Galerucini.
Effect of sorghum resistant to Stenodiplosis sorghicola (Coquillett) (Diptera: Cecidomyiidae) on oviposition and development of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)
Authors: Franzmann Bernard A , Scholz Brad CG
Published: March 2003

Abstract Helicoverpa armigera oviposition preference for, and larval development on sorghum hybrids with differing resistance to sorghum midge, Stenodiplosis sorghicola, were investigated. When H. armigera larvae were fed seed of resistant and susceptible hybrids in the laboratory there were no differences in larval and pupal sizes or the rate of development. The same result was recorded when larvae fed on panicles on plants in a glasshouse. On some sampling occasions, significantly more eggs were laid on panicles of resistant hybrids in the field. This occurred when plants were in plots and also in a mixed planting. Midge‐resistance status did not affect levels of egg parasitism. In a field study using recombinant inbred lines between a midge‐resistant and a midge‐susceptible line, no relationship was found between level of resistance and oviposition of H. armigera. We conclude that, although midge‐resistant hybrids are sometimes preferred for oviposition by H. armigera, the resistance per se does not determine this preference. Egg survival, larval survival, development and resultant damage are not significantly affected by the midge‐resistance status of the host.
Developing methods for quantifying the apparent abundance of fiddler crabs (Ocypodidae: Uca) in mangrove habitats
Authors: NOBBS MADELEINE , McGUINNESS KEITH A.
Published: March 2003

Counting the number of individuals emerging from burrows is the most practical method for estimating the apparent abundance of Australian Uca species living in mangrove habitats. Experiments were conducted to investigate the effect on counts of quadrat design, distance of observer, quadrat size, recovery time and observational technique. Significant differences in the apparent abundance of one species were found when the subjects were within 2 m of the observer, and when a conspicuous quadrat was used. The largest quadrat tested provided the least variability in counts but an intermediate size (0.56 m2) was more practical. Most Uca active within a 30‐min period emerged during the first 10 min regardless of site, species, sex or season. There was a linear correlation between scanning and continuous observation indicating that the former method could be useful when sampling time was limited. Temporal changes in the apparent abundance of Uca suggest that long‐term sampling and more detailed studies will be worthwhile.
Resource use and foraging patterns of honeybees, Apis mellifera, and native insects on flowers of Eucalyptus costata
Authors: Horskins K. , Turner V. B.
Published: March 2003

Introduced honeybees have become well established throughout Australia and concerns have been raised about their impact on the native flora and fauna. Such concerns include the possible depletion of nectar resources by honeybees to the detriment of native animals and the ability of honeybees to pollinate Australian plants. The foraging patterns and resource utilization of honeybees (Apis mellifera) and native insects on flowers of yellow Mallee (Eucalyptus costata) (Behr & F. Muell, ex F. Muell.) were studied in Wyperfeld National Park during spring 1994. Seventy‐four insect species visited the flowers with the most prevalent being honeybees, native bees (Lasioglossum and Hylaeus) and ants (Iridiomyrmex). Honeybees began foraging at lower temperatures than native bees and hence had initial access to the nectar supply that was primarily produced overnight by E. costata. However, the majority (90%) of early morning visits to flowers by honeybees involved the collection of pollen. Honeybees did not forage for nectar in substantial numbers until after native insects were active. Despite both consumption and evaporation, nectar supplies remained available at midday and at one site remained available for consumption at dusk. Honeybees regularly made contact with the receptive stigmata while foraging for pollen and hence had pollen loads consisting of numerous E. costata grains present on their body. These activities are indicative of the behaviour required by insects to facilitate pollination. Given the unique morphology of many native flowers and the contrasting findings from studies to date, it is critical that generalisations about the effect of honeybees in the Australian environment are not made from studies on a limited number of native plant species.
Bias in the effect of habitat structure on pitfall traps: An experimental evaluation
Authors: Melbourne Brett A.
Published: March 2003

Habitat structure has been implicated as a source of bias for pitfall‐trap data but most evidence is observational or anecdotal. This study used an experimental approach to quantify biases due to habitat structure. In a randomized block design, I manipulated native grassland to create three types of habitat structure and measured pitfall‐trap catches of grassland ants. Small patches of modified habitat were surrounded by otherwise unmodified grassland with the assumption that population density remained unaffected by the modification and that the effects observed were due to changes in trappability. I assessed magnitude, direction, predictability, and consistency of bias for the following types of data: population abundance for single species, relative abundance among species, species composition of assemblages, and species richness. The magnitude of the bias in population abundance was large for most species. However, since the direction of the bias varied predictably with habitat structure, pitfall‐trap data can be used to judge differences in population abundance in some situations. The magnitude of the bias in relative abundance was less than for abundance. However, there was inconsistency in the direction and magnitude of bias among species. Thus, interpretation of relative abundance data in pitfall‐trap studies may be compromised. Species richness and species composition were biased by habitat structure but were affected significantly only when the groundcover was very dense, suggesting a threshold effect of habitat structure. To help to interpret survey data, pitfall‐trap studies should routinely measure attributes of habitat structure and incorporate an experimental component to characterize the bias.
Taxonomy of estuarine invertebrates in Australia
Authors: Hutchings Pat
Published: March 2003

An Australian estuary is primarily a marine‐dominated environment, subjected to major salinity changes only after heavy rains and during flood conditions. In southeastern Australia estuarine biota are similar to those in shallow coastal bays and some of the coastal lagoons, and most taxonomic studies on estuarine fauna have occurred in this region. Several major surveys of estuarine and coastal bays have been undertaken in Australia during the past three decades and these surveys have largely provided the material for taxonomic studies of the major groups of macrobenthos. All these studies have revealed a diverse and abundant benthic macrobenthos. The composition of estuarine invertebrate fauna is compared with open exposed coasts, including fauna found in soft strata and on hard strata. Australia has a limited specialized estuarine biota much of which is restricted to particular habitats, and a highly diverse marine community which thrives in the sheltered protected waters of estuaries and the associated soft sediments. Currently, interactive computer‐based keys are being developed which should greatly assist the student and the benthic ecologist to identify the fauna and prevent potential loss of data. Some aspects of the current debate of the level of taxonomic resolution required to answer various ecological questions are discussed. Finally, some comments are suggested as to future directions in which taxonomists and estuarine ecologists should proceed in order to be able to detect changes or losses of estuarine biodiversity and the loss of the associated biological information which may be critical in understanding the functioning of the estuarine ecosystem.
Determining the ‘health’ of estuaries: Priorities for ecological research
Authors: Fairweather Peter G.
Published: March 2003

‘Ecosystem health’ is a relatively new concept for environmental science and management. Although at least two international journals use the term in their titles, there have been few applications of it for estuaries and soft‐sediment habitats around the world. In this paper I: (i) introduce the ideas behind ecosystem health, and assess their relation with other usage such as ‘integrity’ or ‘quality’; (ii) sketch the sorts of multidisciplinary studies that could contribute to an assessment of health of an estuary and how these must be approached in developing useful indicators; and (iii) make a case for including measurements of the rates of ecological processes in such an assessment. These rate measurements, termed ‘ecoassays’, focus on important processes such as decomposition, recruitment, predator–prey interactions, and the like. A case study is introduced wherein these processes were assessed in mangrove stands of estuaries around Sydney, New South Wales, by explicitly comparing the rates of herbivory and decomposition of mangrove leaves, attack of fallen wood by shipworms, and colonization of pneumatophores by algae, as well as with more traditional estimates of ‘standing stocks’. Not surprisingly, the different measures retrieved various patterns and the challenge now is to integrate these into a scheme that indicates something of value. The potential utility of such measures is discussed in relation to the various scientific and managerial requirements of environmental monitoring.
Shallow water benthic ecology: A North American perspective of sedimentary habitats
Authors: Woodin Sarah Ann
Published: March 2003

North American benthic research in sedimentary estuarine environments began with an emphasis on descriptions of organism distributions and abundance. These efforts resulted in a crude map of infaunal assemblage types. This map is not complete even today but the data allow us to ask questions about pattern. As is typical of such efforts, the majority of the techniques used to evaluate the existence of infaunal patterns are correlative and thus result in only weak inferences which do not necessarily expose the causal relationships. Such approaches dominated sedimentary benthic ecology until the 1960s and 1970s when investigators began to concentrate to a much larger extent on elucidating causal mechanisms. The original stimulus for this change has its origins in the work of Sanders and Rhoads and their collaborators who recognized the link between the activities of the infauna and the structure of the habitat. Additionally in the 1970s, several investigators with strong ties to rocky intertidal benthic ecology, where manipulative experiments have been enormously successful, began publishing their work which accelerated the move to address mechanisms through experimentation. During the 1980s and 1990s the emphasis on explicit experiments has continued. In this contribution I explore our current understanding of the processes that lead to patterns of distribution and abundance in marine sedimentary assemblages and our ability to ask testable questions concerning mechanism in this habitat.
Characteristics of the ichthyofaunas of southwestern Australian estuaries, including comparisons with holarctic estuaries and estuaries elsewhere in temperate Australia: A review
Authors: Potter I. C. , Hyndes G. A.
Published: March 2003

Data on the species compositions and the ages, sizes, reproductive biology, habitats and diets of the main species in the ichthyofaunas of seven estuaries in temperate southwestern Australia have been collated. Twenty‐two species spawn in these estuaries, of which 21 complete their lifecycles in the estuary. The latter group, which includes several species of atherinids and gobies with short lifecycles, make far greater contributions to the total numbers of fish in the shallows of these estuaries than in those of holarctic estuaries, such as the Severn Estuary in the United Kingdom. This is presumably related in part to far less extreme tidal water movements and the maintenance of relatively high salinities during the dry summers, and thus to more favourable conditions for spawning and larval development. However, since estuaries in southwestern Australia have tended to become closed for periods, there would presumably also have been selection pressures in favour of any members of marine species that were able to spawn in an estuary when that estuary became landlocked. Furthermore, the deep saline waters, under the marked haloclines that form in certain regions during heavy freshwater discharge in winter, act as refugia for certain estuarine species. The contributions of estuarine‐spawning species to total fish numbers in the shallows varied markedly from 33 or 34% in two permanently open estuaries to ≥ 95% in an intermittently open estuary, a seasonally closed estuary and a permanently open estuary on the south coast, in which recruitment of the 0 + age class of marine species was poor. The larger estuarine species can live for several years and reach total lengths of ~ 700 mm and some estuarine species move out into deeper waters as they increase in size. Several marine species use southwestern Australian estuaries as nursery areas for protracted periods. However, sudden, marked increases in freshwater discharge in winter and resultant precipitous declines in salinity in the shallows, and in other regions where haloclines are not formed, are frequently accompanied by rapid and pronounced changes in ichthyofaunal composition, partly due to the emigration of certain marine species. In contrast, the ichthyofaunal compositions of macrotidal holarctic estuaries undergo annual, cyclical changes, due largely to the sequential entry of the juveniles of different marine species for short periods. The ichthyofaunal compositions of the narrow entrance channels, wide basins and saline riverine reaches of large, permanently open southwestern Australian estuaries vary, reflecting the marked tendency for some species to be restricted mainly to one or two of these regions. Comparative data indicate that the characteristics determined for ichthyofaunas in southwestern Australian estuaries apply in general to estuaries elsewhere in temperate Australia.
Variation in the sublittoral macrozoobenthos of the Baltic Sea along environmental gradients: A functional‐group approach
Authors: Bonsdorff Erik , Pearson Thomas H.
Published: March 2003

The enclosed Baltic Sea, one of the world’s largest brackish water basins, resembles a large estuary with steep horizontal and vertical environmental gradients. Thus, salinities range from 25 to 30 ppt in the Danish Sound area in the south to 1–3 ppt in the inner reaches of the Gulfs of Bothnia and Finland, and a persistent pycnocline in the Baltic basin causes stagnation of bottom waters for long periods, with periodic hypoxia/anoxia as a consequence, over an area covering up to 100 000 km2. Further, climatic variation from boreal to subarctic causes additional stress on the ecosystem. In recent decades, eutrophication and pollution have also significantly affected the biota of the Baltic Sea. The soft bottom infauna is poor in terms of species composition, and functional complexity is considered to be low. This paper examines the estuarine soft bottom infauna of the Baltic Sea along some principal environmental gradients using a functional‐group perspective. We have used the functional‐group concept (primarily feeding type, mobility and microhabitat), designed for polychaetes by
Fauchald and Jumars (1979), to analyze and illustrate if and how the environmental gradients are reflected in the zoobenthos. A total of 25 functional groups were identified, forming clines from complex functional communities in the south and west, towards functionally poor assemblages in the north and east. The shift in functional groups indicates a loss of carnivores, tentaculate sessile organisms, and burrowers from areas beyond the Baltic and its marine approaches towards the inner bays. On the other hand, suspension feeders and surface deposit feeders increase in importance. In the northernmost areas of the Baltic only 1–3 functional groups are found, compared to 8–20 in the south.
Seed germination in Chrysophyllum sp. nov., a large‐seeded rainforest species in north Queensland: effects of seed size, litter depth and seed position
Authors: Green Peter T.
Published: March 2003

Leaf litter affects seed germination in many ways and past studies have shown greater impacts on relatively small seeds, both within and among species. In this shade‐house experiment I examined the impact of forest litter on seed germination in Chrysophyllum sp. nov. (Sapotaceae), a large‐seeded (2.4 g) rainforest tree from north Queensland. Seed mass varies more than 30‐fold in this species, making it useful for studying the role of litter as a possible selective pressure in the evolution of seed size in large‐seeded species. Seeds of varying size (small, medium, large) were sown in planting boxes containing one of three litter levels (low, medium, high) and placed either below or on top of the litter. Seed size and litter biomass had no significant impact on the number of germinating seeds or the time to germination but seeds placed below the litter germinated around twice as frequently, and 20% sooner, than seeds placed on top of the litter. There were no significant interactions between any of the three factors. This shade‐house experiment suggests that leaf litter is not an important selective pressure in the evolution of seed size in this species. However, if litter disturbance under field conditions differentially affects the probability of seed germination in relation to seed size and/or litter biomass, then litter could still act as a selective pressure in the evolution of seed size in Chrysophyllum and other large‐seeded species.
Arboreal arthropod biodiversity in woodlands: Effect of collection procedures and geographic distance on estimates of diversity found on two species ofMelaleuca
Authors: Richardson B. J. , Azarbayjani F. F. , Burgin Shelley , Richardson Sylvia
Published: March 2003

The estimation of the level of biological diversity is critical to conservation planning and management. In this paper, factors affecting arboreal arthropod biodiversity estimates are examined, namely, reproducibility between trees, the proportion of the foliage of a tree that needs to be sampled, the effects of placement position of collectors under the tree and geographical distance between sampled trees of the speciesMelaleuca linariifoliaandM. decora. It was found that arboreal arthropod specimens are not randomly distributed on trees and that, on average, 33% fewer species and 52% fewer specimens occur on the northern (sunny) sides of the trees than on the southern sides. The placement of collectors therefore can radically affect the estimates obtained. The species area curve continued to rise for each host until the entire tree was sampled. The shapes of the curves obtained from the two hosts however, were markedly different and it is concluded that it is not possible to simply transfer protocols from one host species to another, very similar, host species. When the same collecting effort was applied, the same number of species were collected, thoughM. decorasupports twice the number of species asM. linariifolia. Variations of as much as 50% were found between trees of the same species in the number of species present and none of the estimators of biodiversity richness, evenness or information gave consistent results. As a consequence of these observations, the use of changes in standard estimators in decisions related to the management of biodiversity need to be considered carefully. Complementarity, however, was found to be a useful and robust measure of similarity of faunas for both host species. A new descriptor of the geographical distribution of organismal biodiversity, the biodiversity neighbourhood, is described and two methods of measuring it, using either spatial autocorrelation or complementarity, are demonstrated.
Spatial patterns of invertebrate species richness in a river: the relationship between riffles and microhabitats
Authors: Robson B. J. , Chester E. T.
Published: March 2003

This study describes the pattern of invertebrate species richness in a river reach with large differences in habitat complexity at two, hierarchically nested, spatial scales. The aim was to determine whether the mass effect was likely to be increasing invertebrate species richness in epilithic microhabitats in this river. The mass effect is the process by which the species richness of a patch is increased when it acts as a ‘sink’ for species generated by ‘source’ patches. Microhabitat patch types in Mountain River, Tasmania, were distinguished on the basis of physical structure and orientation on the river bed. They were nested within two types of riffle with contrasting structural complexity: bedrock and boulder‐cobble riffles. It was hypothesized that microhabitats with high species richness would act as source patches, contributing species to other microhabitats (sinks) and thereby increasing their species richness. Microhabitat sampling was carried out in four consecutive seasons and rarefaction was used to estimate riffle‐scale species richness. Analysis of variance ( ANOVA) was used to compare the identical microhabitats present in the contrasting riffle types, to detect evidence of the mass effect in either riffle type. The more structurally complex boulder‐cobble riffles had higher species richness than did bedrock riffles. Amongst the microhabitats, the spaces beneath the cobbles had the most species. Microhabitats accounted for a higher percentage of the variation in species richness than did differences between riffles of the same type. No evidence was found for the operation of the mass effect in either riffle type. The majority of species found only in boulder‐cobble riffles were unique to the beneath‐cobble microhabitat and appeared to be unable to colonize other microhabitats, even as transients. In Mountain River, small‐scale habitat characteristics appeared to be more important than larger‐scale effects in determining microhabitat species richness.
The effects of willow and eucalypt leaves on feeding preference and growth of some Australian aquatic macroinvertebrates
Authors: Yeates Lorilee V. , Barmuta Leon A.
Published: March 2003

The effect of leaf species (willow, Salix fragilis L., and white gum, Eucalyptus viminalis Labill.) and leaf state (senescent or green) on the feeding selectivity and growth rates of three species of macroinvertebrate Notalina sp. Mosely (Trichoptera: Leptoceridae), Koorrnonga sp. Campbell and Suter (Ephemeroptera: Leptophlebiidae) and Physastra gibbosa (Gould) (Mollusca: Planorbidae) were tested in the laboratory. All three species of macroinvertebrate selected green willow most strongly over the other leaf types (senescent willow, green eucalypt and senescent eucalypt). Growth rates of P. gibbosa and Notalina sp. were significantly greater on green willow than on the other leaf types. We were unable to measure the growth of Koorrnonga sp. Invertebrates had access to softer internal tissues of leaf material during preference trials, therefore we do not think that leaf structure was the main influence on selection between these materials. Green willow material may have been a better food source because of the noticeably thicker biofilm that it supported, and this material may also retain higher levels of nutrients than abscissed leaves. We speculate that willow leaves may provide a preferred source of food but will be available for less time than native eucalypt detritus.
Population rate of change in the leaf‐eared mouse: The role of density‐dependence, seasonality and rainfall
Authors: LIMA MAURICIO , JAKSIC FABIAN M.
Published: March 2003

We analysed statistically the influence of density‐dependent regulation, seasonality and precipitation on the realized population rate of change of the Neotropical rodent Phyllotis darwini (Waterhouse 1837) at an intra‐annual time scale. We used four years of continuous live trapping at a semiarid locality of north central Chile. Results showed that density‐dependence, seasonal effects and precipitation were important factors influencing population growth rates in this species. An empirical population model including a sine function for seasonal effects, a linear form for density‐dependence, and precipitation was fitted to the full data set and to the data set with the first year removed (after an outbreak). The empirical model explained 33% and 48% of the variance in population growth. The natural rate of population increase, estimated from the empirical model, was rmax = 2.51 or 5.06 years−1. These estimates indicate a great potential for population increase and may explain the capability of this species to undergo large irruptions. We propose that merging empirical and theoretical modelling with field research is the most promising avenue to understand the outbreaks experienced by some rodent species in western South America.
Activity areas and daily movements of an arboreal monitor lizard, Varanus tristis (Squamata: Varanidae) during the breeding season
Authors: THOMPSON G. G. , DE BOER M. , PIANKA E. R.
Published: March 2003

During the breeding season, in the western Great Victoria Desert, Western Australia, male Varanus tristis move greater daily distances (186.5 m) than females (99.7 m) and have larger activity areas (40.3 ha vs 3.7 ha). V. tristis retreat predominantly to live and dead upright Eucalyptus gongylocarpa (marble gum) trees that have hollows in their trunks and limbs. There is no observable difference between males and females in their preferred habitat, but females are found more frequently in a lesser number of preferred retreats during the breeding season.
Oysters as habitat for limpets in a temperate mangrove forest
Authors: MINCHINTON TODD E. , ROSS PAULINE M.
Published: March 2003

In temperate mangrove forests in New South Wales, Australia, the limpet Patelloida mimula Iredale lives on the oyster Saccostrea commercialis Iredale and Roughley, which, along with mangrove trees, provide the only hard substrata in a habitat otherwise dominated by soft‐sediment. The objective of this study was to ascertain the degree of association between the limpet and the oyster by examining their patterns of co‐occurrence in the forest and the relationship between individual pairs of limpets and oysters. Sampling of the distribution and abundance of limpets and oysters throughout the mangrove forest revealed that limpets were rarely present on substrata other than oysters. Patterns of abundance of limpets were, however, not directly related to the amount of habitat provided by the oysters. For example, there was a dramatic decline in the abundance of oysters from seaward to landward in the mangrove forest which was not reflected in the densities of limpets. Consequently, oysters appear to set the limits of distribution of limpets, but other factors modify their broad‐scale patterns of distribution and abundance within these bounds. Limpets leave scars on oysters which might be home sites. About 98% of oysters with limpets had only one limpet per surface of oyster, and the distribution of limpets was overdispersed or repulsed. Moreover, in some areas of the forest, the lengths of limpets were directly related to lengths of oysters. Tracking of individual limpets for 13 days revealed that > 70% remained on the same scar of an oyster. This evidence suggests that for some limpets there is a strong association with particular oysters. Factors determining the distribution, abundance, and sizes of oysters are likely to be important sources of variation to the structure of populations of P. mimula in temperate mangrove forests.
Skeletochronological assessment of age structure and population stability for two threatened frog species
Authors: DRISCOLL DON A.
Published: March 2003

Populations that fluctuate in size may become small at particular times and therefore be at risk of extinction. I used skeletochronology to examine the potential for fluctuations in population size in the threatened frog species Geocrinia alba and Geocrinia vitellina from southwestern Australia. The change in number of lines of arrested growth (LAG) in toe bones of recaptured frogs indicated that most individuals probably gain one LAG annually. Therefore, skeletochronology can be used for age determination. From a combination of skeletochronology and a mark–recapture study, both species appear to live for a maximum of six years. However, the majority of adult males only bred in a single year, which gave rise to a consistently dominant three‐year‐old age class. A drop in the number of two‐year‐old frogs and a large increase in the number of three‐year‐olds (up to 85%) from 1993 to 1994 in both species highlighted the potential for substantial fluctuations in population size. Widespread changes in abundance of between 25 and 50% may therefore be expected over periods as short as one or two years, due to variation in recruitment success.
Frequent fuel‐reduction burning: the role of logs and associated leaf litter in the conservation of ant biodiversity
Authors: Andrew N. , Rodgerson L. , York A.
Published: March 2003

Frequent low‐intensity fires are used in management of Australian forests to reduce fuel loads and protect natural resources and human property. Low‐intensity fires are typically patchy and unburned litter microhabitats are often associated with large objects such as logs, which may act as refuges both for vertebrate and for invertebrate fauna. The aim of this study was to determine whether ants were using unburned leaf litter microhabitats associated with logs as a refuge after fire. The study was carried out in Bulls Ground State Forest, New South Wales, Australia, where experimentally burned and unburned sites had previously been established. Species richness and abundance of ants in leaf litter did not differ between habitats adjacent to logs and away from logs, in burned and unburned sites. Fifteen of the 42 ant species were found in all four habitats, and contributed 94% of total ant abundance. Every habitat had a group of unique species, which together made up 30% of the total species richness. There was also a distinct group of species that was not found in the leaf litter associated with the burned/open habitat. However, as 45% of all species were found in low abundance (less than 10 individuals), care must be taken in inferring patterns for these groups. When functional groups were used to assess community structure, ‘cryptic’ species were found to be common in all habitats, whereas ‘subordinate Camponotini’ were found in burned habitats only. This study indicates that in an area where frequent burning is applied on a broad scale, preserving a range of microhabitats, including those associated with retained logs, may make a substantial contribution to conserving ant biodiversity.