Coastal Restoration Trust of New Zealand

Coastal Dune Ecosystem Reference Database

Modelling of surface roughness for flow over a complex vegetated surface Journal Paper

Pattanapol, W.; Wakes, S.J.; Hilton, M.J.; Dickinson, K.J.M.
Journal / Source
International Journal of Mathematical, Physical and Engineering Sciences
black katipo, distribution, widow spiders, sand-dune
The katipo (Latrodectus katipo Powell, 1871) is one of two endemic widow spiders in New Zealand. It is a coastal sand-dune specialist and national invertebrate icon that has suffered a dramatic decline in numbers, contraction in geographical range and population fragmentation. This nationwide survey of the katipo located 26 populations in 90 dune systems sampled of a total of 127 sites visited where it could potentially be found. Details of the 90 dune systems are presented, including the number of adult female spiders found within a standard search time, degree of naturalness of the dunes and location. A survey of sites where katipo had been collected previously, based on specimens in collections, showed that they were present at only 46% of these sites. On the basis of this study, 19 key sites for katipo conservation are proposed. The katipo is threatened with extinction for a myriad of reasons: the main factors appear to be loss of habitat and declining quality of the remaining habitat. The dramatic changes to its sand-dune habitat following European settlement were due to stock grazing, disturbance and burning, and continue to this day with commercial forestry, recreational use of dune systems and other activities. The subsequent destabilisation of the dunes led to the introduction of marram grass (Ammophila arenaria), which continues to displace native sandbinding species. Marram grass can now become so dense that katipo web construction may no longer be possible. Based on this research, recommendations for the conservation of the katipo are presented. Using the accepted New Zealand invertebrate classification criteria, the katipo is assessed as a Category B threatened species, i.e. a second-priority threatened species
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