Dr. Rosemary Gillespie (University of Hawaii) and I (in a volunteer role for The Nature Conservancy) are convened a symposium on "Issues in Spider Conservation" at the 1998 meeting of the Society for Conservation Biology as an effort to bring together researchers and conservation professionals to discuss the growing body of knowledge related to spider conservation.

All paper abstracts are available on this page, and a symposium description is available here.

Nine papers from the symposium will be published in a Special Issue of the Journal of Insect Conservation in December 1999.

Tim New
School of Zoology, La Trobe University, Bundoora, Victoria 3083, Australia

UNTANGLING THE WEB: SPIDERS AND THE CHALLENGES OF INVERTEBRATE CONSERVATION
Selection of informative focal groups is an important avenue to increasing the applications of invertebrates in conservation assessments and inventory studies, and to help overcome the challenges of high diversity, all-taxon surveys, and taxonomic inadequacy. Spiders are a possible focal group of wide relevance in terrestrial ecosystems, but considerable further work is needed to clarify their broad values as indicators, the relevance of higher taxon surrogacy, the taxonomy of selected families and genera, and to develop standard sampling protocols. The current values of spiders in conservation, and the prospects of enhancing their value as such a focal group are enumerated and discussed.

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MEASURING SPIDER DIVERSITY : EFFECTS OF SAMPLING METHOD, AND DIFFERENT SPATIAL AND TEMPORAL SCALES
Spiders were surveyed in a coastal heathland community using three sampling methods, across three spatial scales, at monthly intervals for 16 months. A total of 8,625 spiders were collected and identified into 33 families, 97 genera and 130 species. There were marked differences in the number of taxa collected by each sampling method: pitfall traps (94% total), visual search (41%) and sweep net (25%). For the number of families and species detected across space and time, the pitfall trap and sweep net methods identified significant, yet contrasting, spatial differences at only one of three spatial scales surveyed. The visual search method indicated no significant differences. In addition, highly significant interactions with time in the pitfall trap results implied that strong temporal variation had to be accommodated to identify spatial patterns in richness, particularly for species richness. Moreover, seasonal analyses revealed an increasing loss of information with coarser temporal scales, with a potential failure to detect significant differences in species richness. These results highlight the risk of using data from limited sampling efforts, especially without a suite of sampling methods, for conservation decision making.

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CATTLE GRAZING IN PUBLIC FORESTS: THE RESPONSE OF SPIDER ASSEMBLAGES
The grazing of cattle is widespread and accepted in most State forests within NSW, yet its impact on forest biodiversity is largely unknown. Grazing, and the frequent, low intensity burning which is used to sustain it, have the potential to change vegetation structure and composition through trampling, selective browsing, the introduction of weed species, and an altered fire regime. The objective of this study is to investigate the long-term consequences of such habitat changes on spider biodiversity in the coastal forests of northern NSW. Spiders have been shown to be sensitive to changes in environmental variables, particularly where habitat structure is altered. As diverse and abundant invertebrate predators, observed changes in spider assemblages may reflect a variety of ecological impacts. Spiders were sampled at sites with varying intensities of grazing but controlled for logging and fire history. A composite sampling strategy of pitfall trapping, litter extraction and sweep sampling was used, and material identified to Family level and morphospecies. Data will be presented with reference to a quantitative habitat assessment. They suggest that the composition of spider assemblages differs at varying intensities of grazing. A threshold grazing intensity may exist, above which spider abundance declines substantially, and the representation of both families and morphospecies is altered.

INCLUDING SPIDERS IN CONSERVATION PLANNING FOR NORTH AMERICA
An examination of the few U.S. Endangered Species Act listings of spiders indicates that under some circumstances the Act may be useful in protecting spiders for which extreme range restriction and imminent threat can be documented.  Increased success may be realized by continuing on a path towards a multi-species, ecosystem-based approach to listings. Recent changes in how candidates for listing are identified have increased reliance on information compiled cooperatively by The Nature Conservancy and the Natural Heritage Network. This network maintains one of the most comprehensive biological databases for rare and imperiled species in North America. However, a review of data currently compiled in this database and a survey of Heritage Programs indicates limited spider knowledge. Since Heritage data is widely used in conservation priority setting, environmental review, and local land-use planning, these data gaps have added significance. The general characteristics of spider fauna, ESA listing requirements, and the paucity of compiled data further emphasizes the need to preempt listings through broader conservation attention to habitat- and range-restricted species.  A preliminary plan for increased outreach to the arachnological community, spider database development, and the eventual incorporation of this information in regional, state, and site level conservation planning is presented.

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RIPARIAN WOLF SPIDERS (ARANEAE, LYCOSIDAE) - INDICATORS FOR NATURAL FLOODPLAIN DYNAMICS
River systems in their natural, dynamic state belong to the most threatened ecosystems worldwide because of human impacts in the form of dams, weirs and bank impoundments. Certain habitats like vegetation-free, riparian gravel banks and their specifically adapted fauna are dependent on the varying flooding regime of the river and the erosion and deposition of its sediment load. Wolf spiders are particularly abundant on riparian gravel banks. Surveys of Central European rivers (Isar, Tagliamento, Rhone, Ain, Dniester) and rivers in South Eastern Australia (Avon, Macalister, Goulburn)since 1995 revealed the coexistence of up to four wolf spider species in densities of up to 77 individuals/sqm. Mark and recapture studies on Arctosa cinerea (Isar River/Germany) and Lycosa lapidosa(Avon River/Australia) demonstrated the dependence of these spiders on large vegetation-free gravel areas.  Furthermore, A. cinerea requires a complex of different soil structures during burrowing and non-borrowing life stages; habitat qualities only maintained by the dynamics of the river.  If the original composition of wolf spider species is known for a river system , then their presence can be used as an indicator for a natural floodplain dynamic. For example, the decline of A. cinerea in Germany is well documented for the last 100 years.

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IMPACT OF CHANGES IN AGRICULTURAL LAND-USE ON SPIDER BIODIVERSITY
Detailed knowledge of the biodiversity of spider communities on agricultural land is important both in terms of pest control and nature conservation. Pitfall traps were used to assess spider biodiversity at 71 Scottish agricultural sites between May and September in both 1996 and 1997. Land-use varied from intensive arable fields, through grasslands, to extensive heather moorland. Spider species richness was found to decrease significantly as land-use management intensity increased. A series of models based on the 1996 spider data (from 50 sites) and a selection of plant, soil and landscape variables were found to explain up to 88% of the variation in spider species richness. Four of these models were used to predict 1997 spider species richness (36 sites - 15 repeat and 21 new) and up to 58% of sites were correctly predicted to within four species. Only 60% of the repeat 1997 sites had species richness values within four of their 1996 score, suggesting a relatively high level of model accuracy. A refined model has been created, including spider data and key environmental variables from both years, and will be used to provide a prediction of the consequences for spider biodiversity of changes to agricultural land use.

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QUANTIFYING EXTINCTION AND COLONIZATION IN SPIDER COMMUNITIES: TURNOVER, PREDICTABILITY, AND RAREFACTION
Terrestrial arthropod assemblages are recently being considered for use as indicators of habitat disturbance and may themselves be targets for conservation programs. Either way, knowledge of the normal temporal variability of such assemblages is required before we can distinguish a community that is ‘under stress’. Using spiders (Order Araneae) as a model arthropod system, I have been quantifying community compositions at six sites in the Southern Appalachians through annual surveys conducted over three consecutive years. Three of these sites were systematically sampled using the same techniques 22 years ago, thus permitting estimation both of short term (yearly) and long term community turnover. Analysis of these data show that turnover in these communities is not especially high when compared with vertebrate groups. The predictability of relative abundance estimates was also quite high. Gross vegetation structure affected the rate of turnover in these communities, with recent clear-cuts having higher turnover rates than adjacent old growth forests. Turnover varied with guild membership, but this may be an artifact of sampling methods. The findings of this study refute the common objection that terrestrial arthropod communities are too variable to be used in biological monitoring programs.

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THE ROLE OF DRIFTNET FENCE LENGTH AND PITFALL TRAP DIAMETER IN SAMPLING SPIDERS IN A WESTERN AUSTRALIAN JARRAH FOREST
Pitfall trapping is a sampling technique extensively used to sample surface foraging invertebrates for biological diversity studies and ecological monitoring.  However, to date, very few invertebrate researchers have considered using driftnet fences to facilitate the abundance and species richness of captures.  This study determines the role that trap diameter
and fence length plays in sampling spiders in a Western Australian Jarrah forest.  Twelve combinations of trap diameters (4, 7 & 11 cm) and fence lengths (0, 1, 2 & 3 m either side of the trap) were examined (12 treatments x 15 replicates = 180 traps).  Two-way ANOVAs revealed no significant interaction effects between trap diameter or fence length. Abundance and species richness were found to increase linearly with increasing trap diameter.  Conversely, there was a rapid increase in abundance and species richness following the addition of the first 1m of fence.  However, the rate of increasing abundance and species richness slowed with each additional meter of fence added.  The addition of a short 1m fence was the most effecient way to maximise catches of spiders (abundance and species richness) rather than through increasing trap diameter.  An optimal combination of trap numbers, diameters and fence lengths for sampling in this habitat is proposed.

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ECOLOGICAL DISTURBANCE AND CONSERVATION OF AUSTRALIAN SPIDERS
This study addresses the impact of ecological disturbances on spiders from the Mesozoic to present day. Mygalomorphs (trapdoor and funnelweb spiders), which are long lived, have adapted to geohistorical shifts in ecosystems but generally do not cope well with sudden or catastrophic events such as fire. Nevertheless disturbance on a minor scale is essential for maintenance of diversity and persistence of species. Human impacts, including forestry practices, pastoralism, agriculture, mining, urbanisation and industrialisation generally alienate mygalomorphs and relictual araneomorphs because such changes occur on a different scale to the life history span of mygalomorphs or because relictual habitats are eliminated. Some human activities including agriculture and creation of dams favour certain araneomorphs particularly aerially borne, web-weaving species but at the same time reduce species richness. Ironically, two of the most venomous  Australian spiders, the Sydney funnelweb (Atrax robustus ) and the redback (Latrodectus hasseltii ) have been favoured by human induced ecological changes that have increased habitat and prey potential; other indiginous species e.g. the black house spider (Badumna insignis ) are now partly anthropochorous. Conservation of spiders requires protection of natural relict and artificially remnant habitats, more moderate use of fire in environmental management and minimal use of insecticides.

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HICKMANIA TROGLODYTES, THE TASMANIAN CAVE SPIDER, AND ITS POTENTIAL ROLE
IN CAVE MANAGEMENT
Cave faunas - which often contain a high representation of spiders - are extremely susceptible to disturbance, and increasing pressure from recreational caving activities and the flow-down effects of epigean habitat degradation pose many previously unforseen problems.  Hickmania troglodytes is a prominent member of the Tasmanian cave fauna, a spider of phylogenetic, zoogeographic and ecological importance, but about which little has previously been known.  Long term monitoring has revealed many unusual life-cycle characteristics in this species, nearly all of which involve long time periods and are dependent upon environmental stability.  The species presents a sensitive and useful tool for the management and monitoring of cave fauna and karst, and provides a visible and obvious proponent of why such systems require protection.  Many promising developments are being made in terms of cave management in Tasmania, but several larger issues are less well addressed and still need to be resolved.

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PATTERNS OF SPECIES DIVERSITY IN A GENUS OF FLORIDA ENDEMICS A PRODUCT OF HISTORICAL BIOGEOGRAPHY AND HABITAT DESTRUCTION
The Florida peninsula has a complex biogeographic history which is reflected by the current distribution patterns of many taxa.  Wolf spiders in the genus Geolycosa are restricted to North America and are obligate burrowers in sandy soils.  Over half of Geolycosa  species are found in Florida and most in the scrub and sandhill habitats on the high, dry, sandy ridges.  These ancient dune systems have a complex geological history, varying in age from over a million years to tens of thousands of years.  We investigated the species distributions of Geolycosa by state-wide surveys of suitable habitat.  We found correlations between species distribution and geological history, and that those species with the most restricted ranges are also found in the most ancient and inland dune systems.  Many of the most restricted species are also dependant on microhabitats which are very sensitive to burn history.  Direct habitat destruction for citrus and housing, and indirect habitat destruction in the form of fire supression, has led to the local extinction of many populations.  The current distribution of Floridian Geolycosa reflects both historical geological processes and current land-use practices.  Data on the biogeography of Florida's Geolycosa will help identify areas of special concern.

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ALLOZYME DIVERSITY IN SPIDERS:  PATTERN, PROCESS AND CONSERVATION IMPLICATIONS
In this report, I summarize estimates of genetic variation based on allozymes for 30 non-social and 4 social spider species.  Social spiders are significantly less variable than non-social spiders, presumably due to high levels of within nest/colony inbreeding.  Among non-social spiders, three main groups are distinguishable in terms of heterozygosity:  A (11%); B (6%); and C (3%).  While variability in group A is comparable to that seen in invertebrates in general (10%), that in groups B and C is much less.  Bottlenecks associated with population establishment and stochastic events (e.g. harsh winters, storms, coastal erosion, human activity) have been commonly cited to account for reduced variability in particular group B and C taxa.  Since the potential for evolutionary change is dependent on the existence of genetic variability, allozyme studies to date suggest that a number of non-social spiders may be at risk in terms of long-term population viability.  Yet, social spider populations typically thrive with only a fraction of the allozyme variability commonly seen in invertebrates and many non-social spiders.  Clearly, future phylogenetic, ecological and genetic studies will be needed to clarify the exact relationship between genetic diversity, gene flow and population viability in spiders.

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NAIVETE AND NOVEL PERTURBATIONS:
THE RESPONSE OF NATIVE SPIDERS TO DISTURBANCE ON OCEANIC ISLANDS
A primary concern in conservation biology is the response of species to habitat disturbance and modification. For a given natural community, the ability of species to accommodate habitat perturbation is often related more to the novelty of the perturbation than to its apparent severity. In this talk I focus on the response of spider species to habitat perturbation in the Hawaiian Islands. I review situations where species have been able to tolerate apparently severe disruption of the habitat, and compare them to situations where naivete or an inflexible behavioral repertoire causes species to decline in the face of disturbances that appear to be relatively minor. Hawaii provides a natural laboratory for studies on the response of species to habitat modification, embracing examples of adaptability to complete modification of the habitat, as well as examples of extreme vulnerability to minor perturbation.

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A CONSERVATION AND MANAGEMENT PROPOSAL FOR NATURAL POPULATIONS OF BRACHYPELMA SMITHI  (ARANEAE, THERAPHOSIDAE) IN MEXICO
In July 1996, as a result of illegal trade, 200 individuals of Brachypelma smithi were caught in Mexican-U.S.A. border. This Mexican endemic species is listed as potentially threatened by illegal trade in CITES Appendix II and as Lower Risk: Near Threatened on the IUCN red list. No adequate protection laws have yet been implemented and thousands of individuals are extracted from their natural habitat. I propose to evaluate the current endangered status of B. smithi in Mexico and start a protection and management plan of this species. Natural populations will be located and studied, where density, distribution, sex ratio, genetic variability and age structure will be analyzed. A global protection plan and conservation strategy is suggested by means of habitat protection, conservation education programs, captive breeding and reintroduction to protected natural habitats in order to diminish illegal trade and local extinction. Population Viability Analysis and long term monitoring will be used to assess survival and reproductive success of released individuals.

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