Nantucket Island and its two smaller neighbors, Tuckernuck and ... â¢The Maria Mitchell Natural Science Museum provided a rallying point for scientific collecting.
Documenting spider diversity on Nantucket Island using citizen science 1,2Andrew
Mckenna-Foster, 1Cheryl Beaton, and 2Michael Draney PhD. 1Maria
Mitchell Association, 4 Vestal St., Nantucket, MA 02554 2University of Wisconsin-Green Bay, Department of Natural and Applied Sciences. 2420 Nicolet Dr., Green Bay, WI 54311
Abstract Methods
• 45 novice collectors have helped during timed collecting or donated specimens they captured casually.
Nantucket
• We estimate that over 100 people have participated in 15 spider walk events.
•We collected in previously established biodiversity plots representing different habitat types: beach dune, forest, grassland, heathland and scrub oak/pine.
• Hundreds have visited the Museum spider exhibits. • We have 3,608 spiders representing ca. 250 species from the Islands.
•We used beat sheets, sweep nets, aerial hand collecting, and ground hand collecting for one hour intervals in each habitat (timed collections). We also collected casually.
• 490 of these spiders, representing 105 species, were collected by novice collectors (Fig. 2).
•We set pitfalls traps and took Berlese funnel samples at each plot.
• 26 of these species (10% of the total species list) were unique and would not be on our list otherwise.
•The Maria Mitchell Natural Science Museum provided a rallying point for scientific collecting expeditions and we maintained live spider exhibits and conducted education programs there.
• We captured 98 species that are in common with Emerton’s list. This suggests that there are 74 species that he captured and we have not.
Spider Walks We took groups of children and adults to areas we needed to sample and let them try out our collecting equipment. We taught them where to look for spiders and discussed the captured species. Most spiders were released unharmed.
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The importance of novice collectors
120
Novice collectors were an integral component to our success (Fig 2). Whether helping us search in the field or donating specimens they caught on their own, novice collectors were the backbone of our collection effort and captured about 42% of the species collected. 3,272
Figure 1. Nantucket Island is 30 miles south of Cape Cod, Massachusetts.
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80
107
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Pitfalls
Figure 3
T otal S pecies 40
20
Tuckernuck Island
x10
x10
Unique S pecies for C ollection
x10
x10
0
# of S piders = 145
S andplain S andplain S crub oak S crub oak D eciduous gras s land heathland pine1 pine2 F ores t 1728
581
212
125
How do we find more species?
Between 1926 and 1929 James H. Emerton created a spider species list for Nantucket (Emerton 1930). He collected 170 named species and two unidentified species. With Emerton’s list as a minimum number of species and an unpublished list of 530 species, compiled by Robert and Eric Edwards for Cape Cod, as a maximum, we estimated the number of species on the Islands to be between 200 and 400. V. Medland
Interesting Species We encountered several interesting species including the Northern Black Widow (Latrodectus variolus) and the Redlegged Purseweb Spider (Sphodros rufipes). We found large aggregations of both species on Tuckernuck Island. On Nantucket we found the species Masoncus pogonophilus, which has only previously been identified from Florida and the upper Midwest.
Emerton collected spiders throughout New England and was one of the great naturalists of his time. Near the end of his life, between 1926-1929, he came to Nantucket Island and collected 172 species creating an important historical record. Our study adds another layer to this record and will be useful in the future. Banks, N. 1932. James H. Emerton. Psyche. 39:1-8
Novice Collectors
Main Collectors
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We need to collect with a variety of collecting methods for a longer time in more habitats. Our sampling effort in sandplain grassland demonstrates this (Fig. 4). In 40 hours of hand collecting (e.g. sweep nets) we caught 48 species. Statistical estimators predict we should be able to catch 70-104 species (Colwell 2005). But, with 5,320 pitfall trap nights (one trap for one night) we have captured 105 species. This is our best sampled habitat. We need to replicate this effort in other habitats to more accurately estimate spider species richness. The dotted line suggests the tupelo forest may have more species than grassland.
120 Total species captured (all methods 2006-2009)
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Number of Accumulated Species
B each D une
Berlese Funnel
We estimate over 300 but it is very difficult to determine. Spiders are highly mobile and species are constantly on the move. We have not sampled all the major habitats completely (Fig. 3). It is clear that the more effort we put into catching spiders, the more species we catch. We have focused on the sandplain grassland habitat because it is globally rare but common on Nantucket.
C ollection Hours
x10
29
So, how many species are out there?
80
Muskeget Island
26
Type of Collecting
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Nantucket Island and its two smaller neighbors, Tuckernuck and Muskeget, are terminal moraines left behind by receding glaciers 15,000 years ago. They are 30 miles south of Cape Cod (Fig. 1) and they lie at the boundary of northern and southern ranges for many species. Due to their location and the residents’ strong conservation ethic, the Islands are reserves for rare habitats, plants, birds, and arthropods. The spider fauna is not well studied.
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3
0
P itfall T rap Nights
Maria Mitchell Natural Science Museum
Total Number of Species Unique Species in Collection
84
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Introduction
James H. Emerton 1847-1931
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Nantucket Island
In 2006, we began an ongoing project to update the species list for the Islands. In addition to collecting species, our continuing goal is to educate residents and visitors by teaching them about spiders and showing them how to collect and identify them. Since 2006, we have focused on the globally rare sandplain grassland habitat which is well represented on Nantucket.
Figure 2
140
Number of Species
In 2006, entrusted with a small budget and depending almost entirely on inexperienced volunteers, we initiated a species survey of spiders on Nantucket Island, Massachusetts. Our goal was to create a dataset useful to land managers by collecting as many species as possible using quantitatively comparable methods. We used the project as an educational opportunity for adults and children and, in turn, harnessed their enthusiasm to collect specimens. Activities included day and night collecting excursions, casual spider collecting events, spider “walks” aimed at children, live spider exhibits in the local natural science museum, and local media coverage for interesting finds. The outcome is a species list representing a majority of the island’s spider fauna (ca. 250 species), permanent live spider exhibits in the museum, new avenues of spider research, and an online electronic field guide to common spiders on the island. In addition, our data provides an important baseline for comparison with historical and future collections to monitor changes in species composition.
Results and Discussion
Chao 2 Estimator ICE Estimator
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Michaelis Menten Estimator 60
Species accumulation for a Nantucket forest Hand captured species
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0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
Number of Collection Hours
Figure 4
The blue curved line in this figure shows how many species we accumulated as we spent more time collecting. Ideally, it would level off at the true number of accessible species.
Future Work We will continue collecting through spider walks and education activities. In 2009, we will be testing a Rapid Assessment Protocol for Spiders and Millipedes developed at the University of Wisconsin-Green Bay and the Chicago Field Museum. An electronic field guide to common species will be available in 2010. Acknowledgments
P. DeVries
The Northern Black Widow lives in grassy areas and is difficult to locate in the wild
We have located large colonies of the Red Legged Purseweb Spider on Tuckernuck. This is one of two tarantula species on the Islands. The male (with red legs) is half the size of the female
P. DeVries
This tiny spider, Masoncus pogonophilus, has previously only been found in Florida and the upper Midwest. It lives inside ant mounds and is probably widely distributed but rarely collected. We collected it in sandplain grassland on Nantucket Island.
Grants from the Nantucket Biodiversity Initiative, Nantucket Land Bank , and Nantucket Land Council and support from the Maria Mitchell Association made this project possible. Numerous collectors and arachnologists donated time and advice, without which, this project would have been impossible. We thank the Nantucket and Tuckernuck Island residents for participating and letting us collect on their properties. We would like to specially thank Dr. Robert Edwards and Eric Edwards for advice on Cape and Island spiders. Unless noted, all photos C. Beaton. Literature Cited Colwell, R.K. 2005. Estimate S: Statistical estimation of species richness and shared species from samples. Version 7.5. User’s guide and application published at http://purl.oclc.org/estimates Emerton, J. H. 1930. Spiders of Nantucket. Pp. 161-172. In Johnson, C.W. 1930. A list of the insect fauna of Nantucket, Massachusetts. Publ. Nantucket Maria Mitchell Association 3(2):1-174, i-xviii.
