| Invertebrata 2002 |
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Development of the Forestry
Tasmania insect collection
Dick Bashford (dick.bashford@forestrytas.com.au) & Simon Grove
(simon.grove@forestrytas.com.au), Forestry Tasmania, GPO Box 207, Hobart TAS
7001
Forestry Tasmania (FT) has a large reference collection of insects and other
invertebrates (Tasmanian Forest Insect Collection). The collection consists mainly of
vouchers and reference series from forest health, quarantine and biodiversity
monitoring programmes and surveys. There are approximately 18 500 mounted
specimens and several thousand held in spirit. The current replacement value of the
collection as assessed by the Australian Valuation Office (January 2002) is $641 801.
Vouchers have been kept as evidence of species occurrence, and as reference material
against which further specimens can be compared and identified. Many are named
species, but many others can only be referred to as morphospecies.
The collection has grown enormously in recent years. However, the
potential benefits that a more comprehensive collection could bring have not been
fully realised. One hindrance is the current approach to voucher storage, in which
material tends to be stored by sampling programme. Some vouchers are dry-mounted,
others are stored in alcohol. This approach was appropriate when the collection was
smaller and more manageable, but is less so now. The main drawback is the difficulty
in comparing material from different sampling programmes. It is very hard to gain an
overview of a species' occurrence across the State, or even to verify that the same
species has been recorded in different sampling programmes, and it is very hard to
use the collection to build up a picture of a species' ecology. Such information is
important for putting names to new vouchers, and is vital in interpreting the presence
or absence of a particular species in a particular sample, whether for biodiversity
conservation studies or for forest health surveys and quarantine collections.
As an example of how useful a unified collection would be, suppose
someone had worked on the litter beetles of Eucalyptus regnans forest in the
Northeast. At a later date, someone else had worked on the log-dwelling beetles of
E. obliqua forest in the Southwest. In each case, 90% of the species had not
been formally identified, but had been sorted to morphospecies. Neither collection
had been databased; they had been lodged at FT but stored separately. When it comes
to analysing the data from the Southwest log study, one key result that cannot easily
be determined is the degree to which the beetle fauna was substrate-specific and
range-restricted. Might some of those species also occur on the other side of the State
in a different forest type and in litter, not logs? Without such information, it becomes
difficult to correctly interpret the analyses, and this weakens their value for forest
management decision-making. Suppose, again, that several apparently 'new' species of
beetle are found in imported wood at a Tasmanian port. Unless they already occur in
an accessible reference collection, it would be be difficult to determine whether or
not they are potential exotic pests. Specimens of the same species might also exist in
the collection from the Southwest log study, but would go unnoticed unless each
separate FT collection was examined.
Collection management at FT requires a new approach, in which the storage
of vouchers is geared more towards their end use. Rather than storing new samples by
sample programme, they should be steadily incorporated into a unified collection
arranged in taxonomic order. For taxa that can be dry-mounted, this should be the
default method. Consolidation will mean that all members of a given species will be
stored together, and close to all members of related species.
This method of storing specimens should be combined with an appropriate
way of storing information relating to them, i.e. databasing. Currently, specimens
from some sampling programmes are databased (or at least recorded on spreadsheets)
while others are not. Using a relational database to store sample, specimen and
taxonomic information would streamline specimen label production and provide a
greater incentive for retaining and maintaining a functional collection of vouchers. It
would also make vastly easier all subsequent data analyses.
The transition from sample-based to taxonomy-based storage may take
several years, depending on the availability of manpower and funds. This is a reason
to start now rather than delay any further. Once sufficient material has been
incorporated into a unified collection and databased, its value should become more
apparent, and it will be easier to justify expenditure on collection development and
maintenance, and to attract external funds to do so.
Long-term maintenance costs per species should be lowered under this
system, primarily because a single species will only require storage space in a single
cabinet, rather than requiring storage space in several cabinets and/or boxes (each
dedicated to a single sampling programme), as at present. A budget has been prepared
to cover the cost of additional cabinets and to equip all existing cabinets with unit
trays (required for quickly moving series of specimens around as the collection
expands).
There may also be additional manpower requirements during the transition.
Time-consuming activities will include mounting and labelling, upgrading old
specimen labels where necessary, databasing, and physically creating the unified
collection as new material comes in and by consolidating the existing collection.
Development of the collection will also require the deposition of voucher
series of forest insects from research projects conducted by other institutions. In
particular students involved in higher academic studies will be encouraged to deposit
vouchers with the collection so that existing identifications are not duplicated and
accrued information on those voucher species can be recorded within the existing
collection database. In time this process will aid in the identification of student
material and reduce identification loads on specialists.
Please contact us if you have voucher material that may be suitable for the
collection or have suggestions for the development of the collection.
A river of dragonflies
Bob Mesibov, Research Associate, QVMAG
A Penguin family reports that huge numbers of dragonflies fly past their
house each summer. The swarming can continue for several hours on still, warm days,
and many thousands of individual dragonflies are involved. The family emphasises
that the dragonflies fly past. It's an enormously long river of insects, not a
large group which hangs around the house.
On Sunday, 3 February, my wife and I visited the family to see the
dragonflies in action. The house is on a hilltop just west of the town, with spectacular
views in all directions. There was a stiff southerly breeze blowing, yet dragonflies
were flying in a fairly steady stream upwind, i.e. from the northern, sea-facing side of
the hill to the southern slope facing the Dial Range further inland. The dragonflies we
saw were flying in a loose formation about 10 m wide.
It was impossible to be sure whether more than one dragonfly species was
involved. We netted two specimens, both of which we identified as Hemicordulia
tau using Allbrook (1979). Allbrook says that in this species 'Emergence is
synchronised, vast swarms of the animals developing' (p. 79), and CSIRO's Insects
of Australia says H. tau 'sometimes migrates in swarms' (CSIRO 1991, p.
309).
Are the dragonflies migrating to Tasmania from the mainland? Has anyone
else noted this species or other dragonflies migrating along the same path year after
year in Tasmania?
References:
Allbrook, P. 1979. Tasmanian Odonata. Fauna of Tasmania Handbook
No. 1. Hobart: Fauna of Tasmania Committee, University of Tasmania.
CSIRO. 1991. The Insects of Australia (2nd ed.). Melbourne: Melbourne
University Press.
Macroalgae habitat change and its effect on lobster
settlement
Sam Ibbott & Caleb Gardner (Caleb.Gardner@dpiwe.tas.gov.au), Tasmanian
Aquaculture and Fisheries Institute, GPO Box 252-29, Hobart TAS 7001;
Larvae of the southern rock lobster (Jasus edwardsii) can spend up
to 24 months in the plankton before they metamorphose from the phyllosoma stage to
become puerulus. The puerulus then actively swim towards shore, where they settle
from the plankton and begin the benthic phase of their life cycle. Monitoring of the
settlement of the puerulus of southern rock lobster J. edwardsii has been
conducted at numerous sites around Tasmania since 1991. This long-term project is
now showing strong links between settlement trends and commercial catches in
adjacent areas, lagged by five years (Gardner et al., in press).
In an attempt to improve precision and reduce variability in the data,
researchers at the Tasmanian Aquaculture and Fisheries Institute modified several
crevice collectors by the attachment of trawl mesh that was suspended above each
collector (see illustration). These modified collectors gave enhanced catches
compared to unmodified collectors at the same site. The structure of a hard, immobile
collector situated below a large flexible structure in the water column is analogous to
that of giant kelp (Macrocystis pyrifera) growing on subtidal reefs. This
combination of reef and kelp is a common habitat type in Tasmania.
Many areas of reef which once supported large communities of M.
pyrifera are altering due to anthropogenic, biological and physical reasons. Large
areas of our coast that were once kelp forests have declined, with up to 90% loss of
these forests along eastern Tasmania. These areas are now dominated by 'urchin
barrens' or by introduced species. There is potential for this broadscale alteration in
community structure to impact upon puerulus settlement and survival. Research
undertaken in the mid-1990s demonstrated that M. pyrifera provides habitat
and food for the early benthic stage lobsters (Edmunds 1995).
We are currently instigating a series of experiments to test the null
hypothesis that the presence of M. pyrifera has no impact on the settlement
rate or subsequent survival of J. edwardsii puerulus. In undertaking these
experiments we also hope to gain a greater understanding of the processes affecting
settlement selection and habitat utilisation of early benthic stage lobsters.
References:
Edmunds, M. 1995. The ecology of the juvenile southern Rock Lobster,
Jasus edwardsii (Hutton 1875) (Palinuridae). Unpublished Ph.D. thesis,
University of Tasmania, Hobart.
Gardner, C., Frusher, S.D. et al. (In press). Relationship between settlement of
southern rock lobster puerulus Jasus edwardsii and recruitment to the fishery
in Tasmania, Australia. Marine and Freshwater Research.
Fig.1. Mesh collector (left) and modified crevice collector (right). Components of the mesh collector were: a) 15 cm diameter styrene float; b) nylon trawl mesh bundled and tied to the main float line; c) 8 mm rope connecting snap clip and float; d) snap clip for attaching mesh to the top of standard crevice collectors as shown.
What is it?
The What is it? in the November 2001
Invertebrata was correctly identified as a histriobdellid polychaete annelid by
Erich Volschenk of the Western Australian Museum. This one is Stratiodrilus
tasmanicus and it lives in the branchial chambers of Tasmanian freshwater
crayfish. Illustration by A. Murray from Beesley, P.L., Ross, G.J.B. & Glasby, C.J.
(eds). 2000. Polychaetes & Allies: The Southern Synthesis. Fauna of Australia.
Vol. 4A. Polychaeta, Myzostomida, Pogonophora, Echiurida, Sipuncula.
Melbourne: CSIRO Publishing, p. 106.
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