Are we predicting the actual or apparent distribution of temperate marine fishes?

Planning for resilience is the focus of many marine conservation programs and initiatives. These efforts aim to inform conservation strategies for marine regions to ensure they have inbuilt capacity to retain biological diversity and ecological function in the face of global environmental change – particularly changes in climate and resource exploitation. In the absence of direct biological and ecological information for many marine species, scientists are increasingly using spatially-explicit, predictive-modeling approaches. Through the improved access to multibeam sonar and underwater video technology these models provide spatial predictions of the most suitable regions for an organism at resolutions previously not possible. However, sensible-looking, well-performing models can provide very different predictions of distribution depending on which occurrence dataset is used. To examine this, we construct species distribution models for nine temperate marine sedentary fishes for a 25.7 km2 study region off the coast of southeastern Australia. We use generalized linear model (GLM), generalized additive model (GAM) and maximum entropy (MAXENT) to build models based on co-located occurrence datasets derived from two underwater video methods (i.e. baited and towed video) and fine-scale multibeam sonar based seafloor habitat variables. Overall, this study found that the choice of modeling approach did not considerably influence the prediction of distributions based on the same occurrence dataset. However, greater dissimilarity between model predictions was observed across the nine fish taxa when the two occurrence datasets were compared (relative to models based on the same dataset). Based on these results it is difficult to draw any general trends in regards to which video method provides more reliable occurrence datasets. Nonetheless, we suggest predictions reflecting the species apparent distribution (i.e. a combination of species distribution and the probability of detecting it). Consequently, we also encourage researchers and marine managers to carefully interpret model predictions.

Physiological assessment of avian exposure to fipronil, a new-generation pesticide

Fipronil, a phenyl pyrazole pesticide, is aerially applied in semi-arid and agricultural areas of Australia to control locust outbreaks. Locust populations build to plague proportions when rainfall occurs in late winter and spring, promoting early vegetation growth. These conditions also attract breeding birds. Over 100 species have been observed coincident with locust control operations. Avian exposure to fipronil occurs via direct contact and by ingesting contaminated insects or seeds. Avian toxicity information demonstrates there is high species-specific variability in fipronil sensitivity in the few avian species studied. There is no research, however, explaining this variability, nor is there research regarding physiological or behavioural sub-lethal effects on avian species. This makes it extremely difficult to predict the toxicity of fipronil on unstudied species at high risk of exposure. Our research aims to resolve this lack of essential information in two ways: firstly we examine whether fipronil has identifiable sublethal effects in exposed birds and their offspring that compromise population health, and secondly evaluate avian metabolism of fipronil in selected species to gain insight into the mechanisms underlying variation in species sensitivity. Our results provide critically needed information for evaluating field effects of locust-control spraying in Australia.

Lichen flora of the Mount Donna Buang Scenic Reserve, Victoria

This report investigated the lichen flora of the Mt Donna Buang Scenic Reserve in Victoria, There were several aims: to describe the lichens of the region, to produce a pictorial key enabling field identification and to determine any distribution patterns. A floristic survey covering approximately 50 square km was undertaken to determine lichen diversity of the region generally. Lichens were sampled along roads, tracks, walking trails and in sections of bush, taking into account forest type and, particularly, areas that were lichen rich. Seventy-five lichen species in 43 genera and 27 families were identified and described from the region. An unknown, species H, also was described. Of the 76 lichen species, 22 were crastose and the remainder macrolichens. The best represented families were: Cladoniaceae (8 species), Hypogymniaceae (6), Lobariaceae (7), Lecideaceae (6), Pannariaceae (6) and Parmeliaccae (6). This study described 12 species (17%) which previously were not known for Victoria and which are a first record for the state. These include: Cladonia sarmentosa (J.D. Hook & Taylor) Dodge, Graphis librata Knight, Parmelinopsis neodamaziana (Elix & Johnston) Elix & Hale, Pertusaria novaezelandiae Szatala, Placopsis pardlina f. microphylla Lamb, Porina leptalea AX. Sm., Pseudocyphellaria ardesiaca Galloway, Trapeliopsis congregant (Zahlbr.) Brako, Menegazzia myriotrema (Mull. Arg.) P. James, Bunodophoron scrobiculatum (Church. Bab,) Wedin, Parmelia testacea Stirton and Menegazzia purpurascens S. Louwhoff sp. nov.. The last eight species are new to the mainland and, apart from Menegazzia purpurascens, previously were known only from Tasmania. Five main elements of distribution were identified for the lichen flora of the Mt Donna Buang Scenic Reserve: cosmopolitan, austral/australasian, paleotropical, pantropical and western pacific. The majority of species (68%) had austral/australasian distributions, eleven (16%) were endemic to Australia and nine (13%) occurred only in Tasmania , Victoria and New Zealand. A pictorial, dichotomous key was constructed for the lichen flora of the Mt Donna Buang Scenic Reserve. Previously, keys to the lichen flora of Tasmanian rainforests were suggested as appropriate to similar areas in Victoria, however, the Victorian forests include a significant sclerophyll element The key presented is specific for the study site but is appropriate to similar regions in Victoria and has been tested in a number of these areas. The key was designed to be ‘user-friendly’ so that the experienced and inexperienced alike are able to use it. A more detailed investigation of the lichen flora of the Mt Donna Buang Scenic Reserve was carried out in order to determine distribution. A total of 50 quadrats, each 20m x 20m in size, were sampled. Within each, the dominant vegetation type was determined and individuals were identified and location noted. The cover abundance of each lichen species on each individual tree was estimated using a modified Braun-Blanquet scale. A total of 710 trees, representing 13 different species, were examined. Nothofagus cunninghamii (Hook.) Oerst, Eucalyptus regnans R Mull., Acacia dealbata Link, A. melanoxylon R. Br., Hedycarya angustifolia A. Cunn. and Atherosperma moschatum Labill. were the six most common tree species encountered at the study site. Nothofagus cunninghamii supported the greatest lichen diversity (39 species), although most species occurred on less than 10% of the trees. The majority of lichens occurring on N. cunninghamii A. melanoxylon, A. dealbata and H. angustifolia were foliose or crustose, those on Ł. regnans fruticose and foliose and those on A moschatum crustose. Bunodophoron australe was the only lichen species at the study site to occur on one host, Nothofagus cunninghamiL Many occurred on a number of different hosts, but were most common on one particular tree species. The distribution of lichens at the study site was analysed with a rnultivariate statistical package (PATN) which dealt with ‘pattern analysis’. The program ‘SSH’ in PATN which uses the Bray-Curtis ordination technique, was used to create scatterplots displaying the degree of dissimilarity between quadrats in terms of presence/absence of lichen species. The program ‘TWAY’ in PATN was used to construct a two way table to display which lichen species occurred in each vegetation type. The pattern analysis revealed that the lichens of the Mt Donna Buang Scenic Reserve were not restricted to any particular forest type, but particular lichens, or groups of lichens, tended to predominate in certain vegetation communities. This concurs with work done by others in Tasmanian forests. Quadrats which were situated in cool temperate rainforest were grouped more closely with each other than with quadrats in other vegetation types. These also supported the greatest number of lichen species. This was not surprising since N. cunninghamii the dominant tree species in cool temperate rainforest, supported the greatest lichen diversity.

The genus Unixenus Jones, 1944 (Diplopoda, Penicillata, Polyxenida) in Australia

The penicillate genus Unixenus Jones, 1944 is widespread, with species found in Africa, Madagascar, India and Australia. Each of the two Australian species was originally described from single samples from Western Australia. In this study, collections of Penicillata from museums in all states of Australia were examined to provide further details of the two described species, to revise the diagnoses for both the genus and the species, and to better understand the distribution of the two species in Australia. In addition, two new species Unixenus karajinensis sp. n. and Unixenus corticolus sp. n. are described.

Sensitivity of fine-scale species distribution models to locational uncertainty in occurrence data across multiple sample sizes

To generate realistic predictions, species distribution models require the accurate coregistration of occurrence data with environmental variables. There is a common assumption that species occurrence data are accurately georeferenced; however, this is often not the case. This study investigates whether locational uncertainty and sample size affect the performance and interpretation of fine-scale species distribution models. This study evaluated the effects of locational uncertainty across multiple sample sizes by subsampling and spatially degrading occurrence data. Distribution models were constructed for kelp (Ecklonia radiata), across a large study site (680 km2) off the coast of southeastern Australia. Generalized additive models were used to predict distributions based on fine-resolution (2·5 m cell size) seafloor variables, generated from multibeam echosounder data sets, and occurrence data from underwater towed video. The effects of different levels of locational uncertainty in combination with sample size were evaluated by comparing model performance and predicted distributions. While locational uncertainty was observed to influence some measures of model performance, in general this was small and varied based on the accuracy metric used. However, simulated locational uncertainty caused changes in variable importance and predicted distributions at fine scales, potentially influencing model interpretation. This was most evident with small sample sizes. Results suggested that seemingly high-performing, fine-scale models can be generated from data containing locational uncertainty, although interpreting their predictions can be misleading if the predictions are interpreted at scales similar to the spatial errors. This study demonstrated the need to consider predictions across geographic space rather than performance alone. The findings are important for conservation managers as they highlight the inherent variation in predictions between equally performing distribution models, and the subsequent restrictions on ecological interpretations.

Visual pigments, oil droplets, ocular media and cone photoreceptor distribution in two species of passerine bird: the blue tit (Parus caeruleus L.) and the blackbird (Turdus merula L.)

The spectral absorption characteristics of the retinal photoreceptors of the blue tit (Pal trs caeruleus) and blackbird (Turdus merula) were investigated using microspectrophotometry. The retinae of both species contained rods, double cones and four spectrally distinct types of single cone. Whilst the visual pigments and cone oil droplets in the other receptor types are very similar in both species, the wavelength of maximum sensitivity (lambda(max)) of long-wavelength-sensitive single and double cone visual pigment occurs at a shorter wavelength (557 nm) in the blackbird than in the blue tit (563 nm). Oil droplets located in the long-wavelength-sensitive-single cones of both species cut off wavelengths below 570-573 nm, theoretically shifting cone peak spectral sensitivity some 40 nm towards the long-wavelength end of the spectrum. This raises the possibility that the precise lambda(max) of the long-wavelength-sensitive visual pigment is optimised for the visual function of the double cones. The distribution of cone photoreceptors across the retina, determined using conventional light and fluorescence microscopy also varies between the two species and may reflect differences in their visual ecology.

Swan foraging shapes spatial distribution of two submerged plants, favouring the preferred prey species

Compared to terrestrial environments, grazing intensity on belowground plant parts may be particularly strong in aquatic environments, which may have great effects on plant-community structure. We observed that the submerged macrophyte, Potamogeton pectinatus, which mainly reproduces with tubers, often grows at intermediate water depth and that P. perfoliatus, which mainly reproduces with rhizomes and turions, grows in either shallow or deep water. One mechanism behind this distributional pattern may be that swans prefer to feed on P. pectinatus tubers at intermediate water depths. We hypothesised that when swans feed on tubers in the sediment, P. perfoliatus rhizomes and turions may be damaged by the uprooting, whereas the small round tubers of P. pectinatus that escaped herbivory may be more tolerant to this bioturbation. In spring 2000, we transplanted P. perfoliatus rhizomes into a P. pectinatus stand and followed growth in plots protected and unprotected, respectively, from bird foraging. Although swan foraging reduced tuber biomass in unprotected plots, leading to lower P. pectinatus density in spring 2001, this species grew well both in protected and unprotected plots later that summer. In contrast, swan grazing had a dramatic negative effect on P. perfoliatus that persisted throughout the summer of 2001, with close to no plants in the unprotected plots and high densities in the protected plots. Our results demonstrate that herbivorous waterbirds may play a crucial role in the distribution and prevalence of specific plant species. Furthermore, since their grazing benefitted their preferred food source, the interaction between swans and P. pectinatus may be classified as ecologically mutualistic.

Occurrence and distribution of established and new introduced bird species in north Sulawesi, Indonesia

Distributional and habitat information on eight introduced bird species in north Sulawesi, Indonesia, is presented. The accounts are based on our observations as well as being gathered from published sources and unpublished trip reports. Three species (Sulphur-crested Cockatoo Cacatua galerita, Sooty-headed Bulbul Pycnonotus aurigaster and Red-collared Dove Steptopelia tranquebarica) have not previously been reported in north Sulawesi in the published literature, while the continued presence and status of Java Sparrow Padda oryzivora, Zebra Dove Geopelia striata and Rock Dove Columba livia was considered uncertain in the published literature. Further work is required systematically to document the distribution, status and spread of introduced species in the north and other parts of Sulawesi—an imperative from both an economic and conservation perspective.

Separating the influences of environment and species interactions on patterns of distribution and abundance : competition between large herbivores

* 1
Much recent research has focused on the use of species distribution models to explore the influence(s) of environment (predominantly climate) on species’ distributions. A weakness of this approach is that it typically does not consider effects of biotic interactions, including competition, on species’ distributions.
* 2
Here we identify and quantify the contribution of environmental factors relative to biotic factors (interspecific competition) to the distribution and abundance of three large, wide-ranging herbivores, the antilopine wallaroo (Macropus antilopinus), common wallaroo (Macropus robustus) and eastern grey kangaroo (Macropus giganteus), across an extensive zone of sympatry in tropical northern Australia.
* 3
To assess the importance of competition relative to habitat features, we constructed models of abundance for each species incorporating habitat only and habitat + the abundance of the other species, and compared their respective likelihoods using Akaike's information criterion. We further assessed the importance of variables predicting abundance across models for each species.
* 4
The best-supported models of antilopine wallaroo and eastern grey kangaroo abundance included both habitat and the abundance of the other species, providing evidence of interspecific competition. Contrastingly, models of common wallaroo abundance were largely influenced by climate and not the abundance of other species. The abundance of antilopine wallaroos was most influenced by water availability, eastern grey kangaroo abundance and the frequency of late season fires. The abundance of eastern grey kangaroos was most influenced by aspects of climate, antilopine wallaroo abundance and a measure of cattle abundance.
* 5
Our study demonstrates that where census and habitat data are available, it is possible to reveal species’ interactions (and measure their relative strength and direction) between large, mobile and/or widely-distributed species for which competition is difficult to demonstrate experimentally. This allows discrimination of the influences of environmental factors and species interactions on species’ distributions, and should therefore improve the predictive power of species distribution models.

Testing the influence of survey method for building species distribution models of marine fishes

Accurate estimates of fish species occurrence are important to any species’ assessments and habitat suitability model. However, surveys of marine fishes are often biased by method. Surveys of marine fishes are often biased by method. Such bias could influence the interpretation of any habitat suitability model. With increasing emphasis on non-destructive sampling, underwater video techniques are commonly used without a thorough understanding of their advantages and disadvantages. This study compared data collected from baited remote underwater stereo-video systems and towed-video systems to provide occurrence data to develop habitat suitability models of nine temperate marine fishes. While numerous studies have compared modelling approaches in terms of model performance (i.e. via AUC or Kappa) the point of this paper was to highlight how very sensiblelooking, well-performing (based on AUC) models can provide different predictions of habitat suitability depending on which dataset is used.

How long should we ignore imperfect detection of species in the marine environment when modelling their distribution?

The application of the 'ecosystem approach' to marine conservation management demands knowledge of the distribution patterns of the target species or communities. This information is commonly obtained from species distribution models (SDMs). This article explores an important but rarely acknowledged assumption in these models: almost all species may be present, but simply not detected by the particular survey method. However, nearly all of these SDM approaches neglect this important characteristic. This leads to the violation of a fundamental assumption of these models, which presuppose the detection of a species is equal to one (i.e. at each survey locality, a species is perfectly detected). In this article, the concept of imperfect detection is discussed, how it potentially influences the prediction of species' distributions is examined, and some statistical methods that could be used to incorporate the detection probability of species in estimates of their distribution are suggested. The approaches discussed here could improve the collection and interpretation of marine biological survey data and provide a coherent way to incorporate detection probability estimates in the modelling of species distributions. This will ultimately lead to an unbiased and more rigorous understanding of the distribution of species in the marine environment.