Behavioural responses of the zebra mussel Dreissena polymorpha to the presence of various gammarid species inhabiting its colonies

Transcription

1 Behavioural responses of the zebra mussel Dreissena polymorpha to the presence of various gammarid species inhabiting its colonies Jarosław Kobak 1 Tomasz Kakareko 2 Małgorzata Poznańska 1 1 Department of Invertebrate Zoology 2 Department of Hydrobiology Faculty of Biology and Environmental Protection Nicolaus Copernicus University Toruń, Poland

2 Ponto-Caspian occur in zebra mussel colonies: Dikerogammarus villosus Dikerogammarus haemobaphes Chaetogammarus ischnus and zebra mussels came from the same region use zebra mussel colonies as shelters and food sources (pseudofaeces, zoobenthos) actively select mussel habitats Gonzalez M, Downing A Can J Fish Aquat Sci 56: Devin S, Piscart C, Beisel JN, Moreteau JC 3. Arch Hydrobiol 158:43-56 Kobak J, Zytkowicz J 7. Hydrobiologia 589:43-54 Kobak J, Kakareko T, Poznanska M, Zbikowski J 9. J Zool 279: Kobak J., Kakareko T, Jermacz Ł, Poznańska M 13. Hydrobiologia 72:

3 Do living in mussel colonies affect the behaviour of their hosts?

4 Methods PVC tiles 1 mussels 2 mm 11 mm mm Aquarium 5 l Aeration Mussels: large (>1 mm) and small (<1 mm) Sand

5 Methods 1 PVC tiles 1 mussels Sand 2 mm 11 mm mm Aquarium 5 l Aeration Mussels: large (>1 mm) and small (<1 mm) Exposure time: 1 i 6 days #2: behind the mesh

6 Methods - gammarid species Dikerogammarus villosus Pontogammarus robustoides Gammarus fossarum alien prefers zebra mussel habitats alien does not prefer zebra mussels native does not co-occur with zebra mussels

7 Methods -measurements 1. Attachment strength 2. Upward movement digital dynamometer 3. Aggregations

8 Attachment strength D. villosus 6 days of N=1 x 1 Attachment strength (N) 1 day of different colours = significant difference SE Treatment x Exposure time interaction: F 2, 113 = 1.9, P <.1 small mussels (<1 mm) large mussels (>1 mm)

9 Attachment strength D. villosus 6 days of N=1 x 1 Attachment strength (N) 1 day of After 6 days in the presence of free D. villosus mussels were more strongly attached Treatment x Exposure time interaction: F 2, 113 = 1.9, P <.1 small mussels (<1 mm) large mussels (>1 mm)

10 Attachment strength P. robustoides 6 days of N=1 x 1 Attachment strength (N) 1 day of In the presence of free P. robustoides mussels were more strongly attached The response was weaker than that to D. villosus Dv Treatment: F 2, 114 = 4.9, P =.9 small mussels (<1 mm) large mussels (>1 mm)

11 Attachment strength G. fossarum 6 days of Mussels did not respond to G. fossarum N=1 x 1 Attachment strength (N) day of.2. small mussels (<1 mm) large mussels (>1 mm)

12 Aggregations D. villosus 6 6 days of N=1 x 1 % of mussles in aggregations No response of mussels 1 day of small mussels (<1 mm) large mussels (>1 mm)

13 Aggregations 6 P. robustoides 6 days of N=1 x 1 % of mussles in aggregations No response of mussels 1 day of small mussels (<1 mm) large mussels (>1 mm)

14 Aggregations 6 G. fossarum 6 days of N=1 x 1 % of mussles in aggregations No response of mussels 1 day of small mussels (<1 mm) large mussels (>1 mm)

15 Upward movement D. villosus 6 days of N=1 x 1 Height above the bottom (mm) 1 day of After 6 days in the presence of free D. villosus mussels more often stayed near the bottom Treatment: F 2, 54 = 7.2, P =.2 Large mussels do not climb up... small mussels (<1 mm) large mussels (>1 mm)

16 Upward movement P. robustoides 6 days of N=1 x 1 Mussels did not respond to P. robustoides Height above the bottom (mm) 1 day of Large mussels do not climb up... small mussels (<1 mm) large mussels (>1 mm)

17 Upward movement G. fossarum 6 days of N=1 x 1 Mussels did not respond to G. fossarum Height above the bottom (mm) 1 day of Large mussels do not climb up... small mussels (<1 mm) large mussels (>1 mm)

18 Mussel responses to Mussels only responded to Ponto-Caspian freely moving among their shells They increased their attachment strength and reduced upward movement The strongest response was observed in the presence of Dikerogammarus villosus, known for its preferences for zebra mussels

19 Mussel responses to Mussels only responded to Ponto-Caspian freely moving among their shells Is it a mechanical irritation? How to check this hypothesis?? The pepper cory (Corydoras paleatus) South American catfish No co-evolution with zebra mussel resistant, temp C constantly searches the bottom for food

20 Methods A single fish A fish ca. 2 cm long Exposure time: 1 i 6 days Feeding of fish: every 2 days Mussels: and large (>1 mm) small (<1 mm) #2: a fish behind the mesh PCV tile 12 mussels Sand

21 Attachment strength 6 days of N=1 x 1 Attachment strength (N) 1 day of After 6 days with fish, mussels were more strongly attached...even if the fish were separated by the mesh! Responses to free-swimming fish were stronger Treatment x Exposure time interaction: F 2, 11 = 6.2, P =.3 Fish fish Fish fish small mussels (<1 mm) large mussels (>1 mm)

22 Agregations 6 days of N=1 x 1 6 In the presence of free-swimming fish, small mussels more often formed aggregations % of mussels in aggregations 1 day of 6 Fish Treatment x Mussel size interaction: F 2, 18 = 3.1, P =.48 fish Fish fish small mussels (<1 mm) large mussels (>1 mm)

23 Upward movement 6 days of 6 In the presence of fish, mussels more often stayed near the bottom N=1 x 1 Height above the bottom (mm) Treatment: F 2, 56 = 18.6, P <.1...even if the fish were separated by the mesh 1 day of Fish fish small mussels (<1 mm)

24 The impact of mechanical irritation on mussels? Mussel responses to fish were similar to those induced by, but stronger Mussels also responded to fish separated by the mesh Some responses of mussels (attachment, aggregations) to freeswimming fish were stronger than their reactions to fish separated by the mesh Thus, mechanical irritation does affect mussel behaviour

25 Zebra mussel responses: Factor Attachment strength Aggregation forming Upward movement Horizontal movement cories predatory roach crushed mussels Toomey MB, McCabe D, Marsden JE 2. J N Am Benthol Soc 21: Kobak J, Kakareko T, Poznańska M 1. Hydrobiologia 644:195-6 Kobak J, Kakareko T 9. Fundam Appl Limnol 174:193-4 Czarnołęski M, Müller T, Adamus K, Ogorzelska G, Sog M 1. Fundam Appl Limnol 176:

26 Thank you very much for your attention Kobak J, Poznańska M, Kakareko T, 12. Behavioural changes of zebra mussel D. polymorpha induced by Ponto-Caspian. Biological Invasions 14: