Extracts from a paper
by
Dipl.-Biol. Lars Hendrich
A pool in Scott
Creek, near Mackereth Cottage
| The Water Beetles of Scott Creek Conservation Park | |
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A pool in Scott
Creek, near Mackereth Cottage
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INTRODUCTION
Invertebrates (ants, aquatic beetles and jewel beetles) were sampled by Archie
MacArthur (South Australian Museum, Adelaide), Lars Hendrich (Free University
of Berlin, Germany), Stephan Gottwald (Berlin, Germany) and Tom Hands (Friends
of Scott Creek Conservation Park, Adelaide) during two one day field trips in
December 1999 in Scott Creek Conservation Park. Previously the park has not
been well investigated for invertebrates, therefore the study provided some
interesting regional records.
Water beetles are an important animal group in Australian freshwaters. In wetland
management, water beetles prove to be an important biomonitoring group. They
inhabit virtually every kind of fresh- and brackish water habitat, from the
smallest puddles up to large lakes and swamps and from streams to irrigation
ditches and reservoirs. Due to their diversity in terms of species numbers,
variation in size and ecological niche they represent an ideal group for environmental
impact assessments (ElAs), conservation assessments and biodiversity studies
in a wider sense (WATTS, 1989).
Hopefully the present report will prove useful for conservationists monitoring
the biological health of freshwater habitats in the park.
| COLLECTING
PROCEDURES Most of the specimens were collected using different kinds of aquatic dip nets and metal kitchen strainers Diameters of meshes varied from 500 to 1000 microns. Leaf litter and aquatic vegetation were swept heavily; the material obtained was then placed on a white 1m x 1m nylon sheet. Specimens were sorted with forceps and/ or an aspirator. Less active species or individuals were traced by carefully sorting the substrate. Beetles from springs, small puddles and streams can frequently be directly sampled with an aspirator or a pair of forceps. Specimens of Hydrophilidae and Hydrochidae were collected by washing leaf litter and grass mats at the edge of a water body. The beetles, which usually cling to the substrate, are thus released and float on the water surface, where they can then easily be picked up with an aspirator. |
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The exposed, swampy and shallow puddle of an almost dry creek - completely covered with Juncus and mats of floating grass. This is the habitat of Platynectes reticulosus, a predaceous water beetle.
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LOCALITIES
SAMPLED
Field work was carried on 13th December 1999 and 18th December 1999. The survey
area of this study included most aquatic habitat types of the park. The dominant
habitats in the park are intermittent creeks and old farm dams and ponds, often
with acidic water. In winter and spring temporary and shallow pools in heath-
and grassland may exist. Those sites appearing to be of particular interest
for the likelihood of finding interesting species were most intensively sampled.
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THE
SPECIES AND SPECIMENS COLLECTED The greatest
diversity was met in a Blackwater Dam... This old farm dam held 15 species
including a population of the largest (over 3 cm) predaceous water beetle
of South Australia, Onychohydrus scutellaris. |
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| The habitat of Platynectes reticulosus. |
Of the 25 species
recorded here, 6 species are restricted to standing waters (lentic sites), while
only one species, the whirligig Macrogyrus angustatus, is found in lotic situations
only.
However, in some cases this division is difficult as different habitats often
merge into one another, especially in the dry summer period when the study took
place, and many creeks and small streams started to drawn. A good example is
the predaceous water beetles Platynectes reticulosus and Necterosoma dispar,
in which larvae and adults occur in stagnant rest pools of intermittent creeks,
as well as in slow flowing permanent streams.
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Necterosoma dispar (Germar, 1848). Photo by author. |
| Sternopriscus clavatus (Sharp, 1882) Photo by author. |  |
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At least
18 species were found in both lotic and lentic habitats. Seven species
occur in permanent and temporary habitats and 18 species are restricted
to more permanent water bodies. (There is a full
list available). The list
of the aquatic beetles of Scott Creek Conservation Park is far from being
complete. No temporary puddles or pools have been sampled during the short
fieldtrip. So there is no doubt that further studies in winter and spring
will reveal additional species. ACKNOWLEDGEMENTS
Dipl.-Biol. Lars Hendrich, Moerchinger Strasse, 115 A D-14169 Berlin, Germany (e-mail hendrich1@aol.com)
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A half shaded permanent and deep blackwater pool. A shallow bay rich in aquatic vegetation, rotten leaves and twiggs. Habitat of Haliplus australis, Sternopriscus clavatus and Onychohydrus scutellaris. |
All habitat photos
by Lars Hendrich. Stephan Gottwald (Berlin, Germany), who assisted in the collection,
also took some excellent pictures of the Jewel
Beetles commonly found in the Park.
