Carp (Cyprinus carpio) are alien freshwater fish that are globally widespread and often
associated with highly degraded freshwater ecosystems. This study explored carphabitat
interactions that could contribute to the worldwide distribution of, and
consequent ecological impacts by, carp. Particular emphasis was placed on the role of
carp size in these interactions. One component of this study involved a field experiment
that was used to quantify the effects of carp biomass density and size-structure on
freshwater invertebrate communities and water quality. The treatments in this field
experiment comprised different combinations of large (2 kg) and small (0.7 kg) carp,
and low (330 kg.ha-1), intermediate (570 kg.ha-1) and high (650 kg.ha-1) biomass
densities. Carp impacts were more carp size-dependent than described in previous
studies. In particular, carp size was more important than carp biomass density in
determining the concentration of total phosphorus and algal biomass. On the other hand,
a more even mix of carp sizes increased total nitrogen. The zooplankton and
macroinvertebrate taxa that were more abundant in the presence of carp were the taxa
most able to avoid carp predation and tolerate habitat changes caused by carp
benthivory. To complement the small-spatial scale field experiment, large-scale patterns
of carp distribution, biomass density and recruitment were explored among the rivers of
New South Wales (Australia) in relation to their physical habitat. In contrast to
expectations, and although most recruitment probably occurred at lower-altitudes, the
populations with a size structure and biomass density most likely to cause ecological
degradation occurred at intermediate altitudes. Furthermore, the distribution of smaller
carp (less than or equal to 100 mm, and less than or equal to 300 mm) indicated that the
regulation of river flows does not always favour carp populations, particularly during
drought conditions. Nevertheless, it was concluded in a review of the carp literature,
which incorporated the findings of this study, that invasion by alien carp is most
successful in streams with formerly highly variable flows that are now subject to flow
regulation. Moreover, carp are likely to enhance their advantage in these waters through
habitat modification.
| Identifer | oai:union.ndltd.org:ADTP/218591 |
| Date | January 2002 |
| Creators | Driver, Patrick, n/a |
| Publisher | University of Canberra. School of Resources, Environmental and Heritage Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | ), Copyright Patrick Driver |
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