Water Conditions of the Habitat of the Water Spider Argyroneta aquatica(Araneae: Argyronetidae) in Mizoro Pond.

Abstract

MakotoYoshida3~ and Yoshiaki Nishikawa4Ã bstract The water spider, Argyroneta aquatica, is the only spider that lives under water. In Japan, due to the fragmentation and the deterioration of the habitat, a policy for conservation of this spider is needed without delay. However, there is no information about the water condition of the habitat of this species. As a study of the conservation of the water spider, we conducted field surveys on the measurement of temperature, pH, and DO (Dissolved Oxygen) of the water in Mizoro pond, which is a habitat of the water spider, in May 1996. The water in which the water spider lived had lower pH and DO than the water in which the water spider did not live. It appears that this low DO value does not allow fishes to live. Consequently, the low DO would prevent potential predators, such as fishes, to live in the habitat of the water spider, giving an enemy free space to them. This low pH and DO is thought to be kept by the activity of sphagna, which is important for habitat conservation of the water spider in Mizoro pond.

Predatory and competitive interaction in Anopheles gambiae sensu lato larval breeding habitats in selected villages of central Uganda

“…In retrospect, it would be recommended that when a similar sampling approach is used, microhabitats/quadrats could be further characterized in terms of water depth, distance from the water edge and aquatic vegetation, which are likely important predictors of the aquatic arthropod communities. While unable to fly, Cybaeidae are thought to reach new habitats via the dispersal of juveniles which are thought to use silk threads to catch the wind [ 70 , 71 ]. Given the narrower set of conditions in which this taxon was found in numbers alongside An.…”

The diving bell and the spider: the physical gill of Argyroneta aquatica

“…Not surprisingly, pure CO 2 caused marked activity involving surfacing, gas replenishment and diving bell building, but there was no significant effect of O 2 replacement. Masumoto et al observed the distribution of A. aquatica in a pond in Japan and found that the spiders seemed to prefer areas where sphagnum occurred in association with low pH and low partial pressure of O 2 (P O2 ), in the region of 0.7-2.3kPa (Masumoto et al, 1998a). In another study, Masumoto et al carried out continuous observations of individual spiders in aquaria over several days (Masumoto et al, 1998b).…”

“…not require renewal of diving bell O 2 from the surface in the short term. Nevertheless, renewal may be necessary in other locations, possibly in acidic ponds (Masumoto et al, 1998a), in highly eutrophic waters (Seyyar and Demir, 2009) or at high altitudes (Walder, 1995). It has been implied that air renewal is necessary during the summer, but not winter, presumably because metabolic rate is higher in summer (Messner and Adis, 1995;Schütz and Taborsky, 2003), but the present experiments show that the physical gill can supply all requirements, even in stagnant water and at abnormally high (22-31°C) temperatures.…”

Time Budget of Activity in the Water Spider Argyroneta aquatica(Araneae: Argyronetidae) under Rearing Condition.

“…Because the oxygen consumption in the water spider is approximately half the minimum oxygen consumption rate of Tegenaria (Stranzny & Perry 1984), one-third the oxygen consumption rate of the wolf spider Pardosa lugubris (Edgar 1971), and similar to the low values measured for Theraphosid spiders (Anderson 1970). The water spider seems to have adapted to the environment with low oxygen concentration (Masumoto et al 1998). The low activity especially in the daytime in juveniles and adult females may reduce the risk of predation by day-active predators.…”