Ecological impacts of filter-feeding Asian carps (Hypophthalmichthys spp.) in Lake Balaton, Hungary
Gergely
Boros1*,
Zoltán
Vitál1,
Attila
Mozsár1,
Gábor
Borics2,
Judit
Görgényi2,
Vilmos
Józsa3,
László
G.-Tóth1,
István
Lehoczky4,
Balázs
Kovács5,
Gabor
Vasas6,
Mátyás
Présing1,
Hajnalka
Horváth1 and
András
Specziár1
-
1
MTA Centre for Ecological Research, Balaton Limnological Institute, Hydrozoological Dept., Hungary
-
2
MTA Centre for Ecological Research, Danube Research Institute, Department of Tisza River Research, Hungary
-
3
Research Institute for Fisheries, Aquaculture and Irrigation, NARIC, Hungary
-
4
Research Centre for Farm Animal Gene Conservation, Hungary
-
5
Szent István University, Research Centre for Farm Animal Gene Conservation, Hungary
-
6
University of Debrecen, Department of Botany, Hungary
Bighead carp (Hypophthalmichthys nobilis), silver carp (H. molitrix) and their hybrids (collectively referred as Asian carps−AC) are primarily planktivorous cyprinid fishes that have been introduced into more than 30 countries around the world, including Hungary. However, recent studies demonstrated that AC can adversely affect the water quality and native fish populations. In this study, we report on the rate of hybridization, growth parameters and feeding habits of AC, to assess their ecological impacts and life history traits in the oligo-mesotrophic Lake Balaton. We found that the majority of the investigated AC (n=116) were hybrids. In general, hybrid AC with silver carp characteristics dominated the stock (90%), but 10% of individuals exhibited bighead carp phenotype and the proportion of bighead carp genes exceeded 98% in 4 individuals. However, the variance in phenotypes and the rate of hybridization did not influence significantly the feeding habits. Rather, the food composition was determined by the availability of different food resources and the concentration of suspended inorganic particles in the ambient water. Stable isotope analyses and microscopic analyses of gut contents revealed that the vast majority (>99%) of the ingested and metabolised food was zooplankton (mainly Rotifers, Cladocerans and Copepods). Despite the low proportions of algae in the food, we identified 155 phytoplankton taxa in the foregut-contents, among which there were several species (e.g., Scenedesmus spp. and Microcystis spp.) that survived the passage through the guts. Growth rates of AC were intermediate in Lake Balaton, while their condition factors were relatively high compared with other ecosystems. The relatively high condition factors were particularly interesting in the light of the high inorganic matter content of ingested food (43±9% in dry mass). We conclude that the presence of AC is an ecological threat to Lake Balaton, because AC can be important resource competitors of native planktivores.
Acknowledgements
This research was supported by the Hungarian Scientific Research Fund (OTKA) Grant K83893.
Keywords:
Bigheaded carp,
Asian carp,
invasive species,
feeding,
Reproduction,
Genetics
Conference:
XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015.
Presentation Type:
Oral Presentation
Topic:
Ecology, Conservation and Invasive Species
Citation:
Boros
G,
Vitál
Z,
Mozsár
A,
Borics
G,
Görgényi
J,
Józsa
V,
G.-Tóth
L,
Lehoczky
I,
Kovács
B,
Vasas
G,
Présing
M,
Horváth
H and
Specziár
A
(2015). Ecological impacts of filter-feeding Asian carps (Hypophthalmichthys spp.) in Lake Balaton, Hungary.
Front. Mar. Sci.
Conference Abstract:
XV European Congress of Ichthyology.
doi: 10.3389/conf.fmars.2015.03.00019
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Received:
28 Oct 2015;
Published Online:
04 Nov 2015.
*
Correspondence:
PhD. Gergely Boros, MTA Centre for Ecological Research, Balaton Limnological Institute, Hydrozoological Dept., Tihany, H-8237, Hungary, boros.gergely@okologia.mta.hu