It’s time for the summer holidays but not everyone is relaxing, 12 young scientists are out conducting research in the field. Summer Drylands Programme (SDP) is a two month field research training internship that gives undergraduates and postgraduate students a chance to conduct field research on a specific topic.
SDP was initiated by the Gobabeb Research and Training Centre with the aim of increasing tertiary students’ practical experiences. SDP 20 students come from different study fields such as microbiology, water management, environmental science, nature conservation, agriculture and animal science to name just few. This year’s SDP theme is the impacts of artificial water points for wildlife conservation in the Namib Desert. We are determining whether or not the piosphere effect exists in the hyper arid Namib Desert. The piosphere effect describes the gradient of disturbance that one finds around water points—often the area surrounding the water point in close proximity is the most disturbed (bare trampled soil, with very few to no plants), with the disturbance lessening in intensity the further one moves away from the water point. As part of the project we determined the presence of scorpions and bats around water points as an indicator of the localized impact of grazing on vegetation and soil disturbance, and its wider impact on small animal communities.
Movies and popular culture label scorpions as threatening, even though not all scorpions carry enough venom to be dangerous and they range in size from large to tiny. Scorpions are well adapted to the harsh conditions of the Namib Desert. They play a vital role in arid environments, where microbial activity are relatively low, because the burrows improve the soil structure and quality. Scorpions dig burrows that aerate the soil and allow water to penetrate deeper into the soil. The presence of scorpion burrows also indicates looser soil within an area of low disturbance as they can’t dig their burrows in rocky soil or with high levels of trampling. The burrowing scorpions we looked for are about the size of an index fingertip. Scorpions are nocturnal and come out of their burrows at night to hunt, mate and enjoy the cooler weather. As such, we determined the presence of scorpions around artificial water points by going for scorpion hunts at night near the sampling plots. In addition, during the day we checked for scorpion burrows within the plots we sampled.
Scorpion hunting was probably the most exhilarating experience of the fieldwork. Setting off from the campsite at sunset armed with florescent torches and purple hued ultra violet (UV) lights was exciting and a little scary. All scorpions glow under UV light because fluorescent chemicals are secreted from their cuticles on their exoskeletons which produce a Cyan-green glow. Thus, the scorpions become visible under a UV beam. We trampled through our allocated plots in search of tiny glow-in-the-dark scorpions. Unfortunately, our search was in vain as we did not see a single scorpion. However, we did see a dwarf adder snake and enjoyed the desert night sky. Walking under the stars in the cool desert that was only a few hours earlier blazing hot was an indescribable experience. Scorpion hunting formed an evening with learning that science doesn’t stop when the sun sets, and that planning and preparation is everything for a successful night in the field.
The absence of any scorpions in the study areas wasn’t actually a failure for our project, but helped us conclude that high animal presence effects small organism as well as soil and vegetation. Additionally, the soil type could serve as a reason for the low scorpion density as scorpions require loose soil to build burrows. The timing and duration of our hunt could also be an explanation for the inability to observe any scorpions. Perhaps next time we will know to look longer or later at night.
SDP also ventured into the science of bats and their presence and utilization of the studied water points. Bats can be used as indicator species, and monitoring bats can help people beter undersand the health of an area. A water point within an unhealthy ecosystem containing little vegetation and insects will be expected to have fewer bats. They are one of the few flying mammals and are known for their use of echolocation, the process of locating their surroundings through sound reflection or echoes, as well as nocturnal flying. There are about 50 species of bats in Namibia which include the slit faced bat and the Dayak fruit bat. Bats have live births and the male Dayak fruit bat lactates to help breastfeed their young. To study bats we set up nets at dusk over the water source. The nets overlapped each other in such a way that no bat could escape its clutches. The wind caused the nets to blow and seem obvious to the human eye, but since bats use echolocation they are unable to see the net and thus become entangled. Of course, this capture method does not cause any harm to the bats.
At Natab, Ganab and Sossusvlei we did not catch any bats but luckily enough we caught one bat at Escourt. With the help of our bat expert Angela Curtis, senior research technician and masters student at Gobabeb, we took measurements on the bat such as colour, head size, gender and collected a DNA sample for identification. We identified the bat as a lactating Eptesicus hottentotus. We released her as soon as we finished our observations.
We observed that small, often overlooked creatures of the desert such as scorpions and bats are impacted by the piosphere effect. Possibly, the reason why we did not find scorpions and found only a single bat is that within a piosphere there is a reduction of flora. The lack of sufficient vegetation results in a reduced number of insects, which scorpions and some bat species feed on.
Initially the survey on bats and scorpions seemed disconnected and unrelated to the other field work we conducted with SDP, but they turned out to be some of the most exciting aspects of the research. These surveys showed that two seemingly unrelated organisms to our study may be of great importance for evaluating the piosphere effect. The study of bats and scorpions showed us how the ecosystem is all connected. Nothing in nature can completely stand alone, including scorpions and bats.
By Hamalwa Hafeni, University of Namibia, BSc Microbiology (Hons) Panashe Mataranyika, Namibia University of Science and Technology, MSc Integrated Water Resource Management