M Normant, J Korthals - Epibiota associated with setae on chinese mitten crab claws - страница 1

Страницы:
1  2 

Epibiota associated with setae on Chinese mitten crab claws (Eriocheir sinensis H. Milne-Edwards, 1853): a first record[1]

Eriocheir sinensis Non-native species Catadromous Temporary epibiota

KEYWORDS

Monika Normant

Jakub Korthals

Anna Szaniawska

Department of Experimental Ecology of Marine Organisms,

Institute of Oceanography, University of Gdansk,

al. Marszalka Pilsudkiego 46, PL-81-378 Gdynia, Poland;

e-mail: ocemn@univ.gda.pl

Received 28 February 2007, revised 2 March 2007, accepted 5 March 2007.

Eriocheir sinensis H. Milne-Edwards, 1853 is a non-native species found in European waters. Analyses of mitten crabs caught in brackish waters (Gulf of Gdansk, Poland) and in freshwater (Havel River, Germany) have indicated that numerous epibionts (possibly temporary) inhabit the dense setal mats that cover the chelipeds. Of the 950 associates found on 22 crabs collected from brackish water, the most abundant were Nematoda (82.3%), followed by Bivalvia (10.3%), Crustacea (5.6%), Oligochaeta (1.2%) and Gastropoda (0.6%). In comparison, 1280 specimens (Chironomidae - 67.6% and Halacaridae - 32.4%), were identified from 13 crabs collected in freshwater. As this crab can migrate long distances, it is capable of transporting native and non-native species via its mittened claws to new habitats.

Abstract

1. Introduction

Eriocheir sinensis Milne-Edwards, 1853, a native species of China and Korea (Leppakoski & Olenin 2000), was first recorded in the River Aller, near Hamburg (Germany) in 1912 and has since dispersed to other European countries (Rasmussen 1987, Vincent 1996, Clark et al. 1998, Cabral & Costa 1999, Gollasch 1999, Valovirta & Eronen 2000, Paunovic et al. 2004, Panov 2006). The Chinese mitten crab is a catadromous species that lives most of its life in freshwater, but migrates downstream to reproduce and spawn in higher salinity waters (Panning 1939). This crab presents a substratum for green algae, red algae, bryozoans, tubes of polychaetes, and mussels (Panning 1952, Kobayashi & Matsuura 1994). Recent studies of mitten crabs have shown, however, that the dense setal patches on the chelipeds might offer an additional habitat for a number of small organisms. As this exotic crab is capable of migrating long distances, up to 18.1 km per day (Herborg et al. 2003), it is possible that both native and non-native species may be transported to new habitats in the setal mats of its claws. The present paper reports for the first time on the occurrence of the epibiota collected in the mittens of E. sinensis from the Gulf of Gdansk (Poland) and the Havel River (Germany).

2. Material and methods

The analysis was based on 22 crabs (3 females and 19 males) collected in the Gulf of Gdansk (Poland) during 2002-2005, and 13 specimens (7 females and 6 males) caught in the Havel River (Germany) during September 2004. The crabs were caught in flounder nets or in fyke-nets and after collection were frozen at —20°C. In the laboratory the crabs were sexed on the basis of the abdominal structure (Panning 1952), after which their carapace width and claw length were measured using a slide caliper (± 0.1 mm). Next, the setae covering the claws were removed with a scalpel and analysed under a stereomicroscope EVB-208 (ECOTONE, Poland) in order to identify the higher taxa present (Stanczykowska 1986).

Linear regression (y = ax + b) and determination coefficients (r2)were used to describe the relationship between the investigated parameters at a significance level of p < 0.05.

3. Results

The carapace width of the Polish crabs ranged from 53.5 to 73.3 mm, the claw length from 35.9 to 59.2 mm (Table 1). The carapace width of the German crabs ranged from 64.0 to 80.7 mm, and the claw length from 35.2 to 62.7 mm. The correlation between carapace width and claw length was

Table 1. Eriocheir sinensis: data on the 22 individiuals from the Gulf of Gdansk and the 13 individiuals from the Havel River (CW - carapace width, M - male, F - female, CL - claw length)

Crabs from the Gulf of Gdansk Crabs from the Havel River

Sex

CW

CL

Number

Sex

CW

CL

Number

 

[mm]

[mm]

of epibiota

 

[mm]

[mm]

of epibiota

M

53.5

35.9

5

F

64.0

35.2

45

F

54.6

32.8

20

F

65.8

46.2

31

M

58.5

37.6

21

F

67.4

48.2

94

M

58.6

38.9

32

F

68.2

37.2

155

M

58.6

39.8

15

F

69.5

39.4

67

M

58.6

39.9

24

F

70.7

40.2

23

M

59.3

40.1

16

F

72.7

39.7

52

M

59.5

40.6

66

M

73.8

53.9

216

F

62.1

34.0

59

M

74.3

54.6

217

M

62.3

44.2

58

M

75.2

42.3

201

M

62.9

45.0

96

M

76.0

43.3

128

M

63.9

45.3

18

M

79.9

62.6

10

M

64.3

46.8

130

M

80.7

62.7

41

M

65.0

48.6

153

 

avg. ± SD

avg. ± SD

avg. ± SD

M

65.5

49.1

28

 

71.9 ± 5.1

46.6 ± 9.3

91 ± 78

M

65.6

49.1

26

 

 

 

 

M

66.2

49.3

16

 

 

 

 

M

66.7

51.7

16

 

 

 

 

F

70.2

40.2

20

 

 

 

 

M

71.4

54.2

15

 

 

 

 

M

73.2

59.2

45

 

 

 

 

M

73.3

59.2

71

 

 

 

 

avg. ± SD avg. ± SD avg. ± SD 63.4 ± 5.5   44.6 ± 7.4      43 ± 39

statistically significant (p < 0.05). Males had longer claws than females of the same carapace width.

Respectively representing 82.3% and 10.3% of all recorded specimens, Nematoda and Bivalvia were the most abundant organisms recorded from the claws of crabs collected in the Gulf of Gdansk. Less frequent were Crustacea, Oligochaeta and Gastropoda, which respectively made up 5.6%, 1.2%, and 0.6% of all the recorded specimens. 86.8% of the crustaceans belonged to the Harpacticoida, 13.2% to the Amphipoda.Thenumber of specimens found in the setae of individual crabs collected in the Gulf of Gdansk varied from 4 to 153 (av. 43 ± 39). The percentages of the various taxonomic groups on the claws of E. sinensis individuals differed (Fig. 1a). The numbers of Nematoda found on individual crabs ranged from 1 to 137, Bivalvia from 1 to 15, and Crustacea from 1 to 13. One or

О

100 80 60 40 20

0

a

Ш

mm

WW

WW

В П

m

12 3   4  5  6 7   8   9 10 11 12 13 14 15 16 17 18 19 20 21 22

crabs

Nematoda       q Bivalvia       q Oligochaeta       Gastropoda       ц Crustacea

r

100 80 60 40 20

0

1    2    3   4   5   6    7    8 910111213

crabs

I Halacaridae    I  I Chironomidae

Fig. 1. Percentage of different taxa found in the setae covering the claws of Eriocheir sinensis individuals collected in the Gulf of Gdansk (a) and the Havel River (b)

1

a

two oligochaetes, and just one single gastropod were noted. In comparison, a total of 1280 specimens were found in the setae of the 13 crabs from the Havel River. These specimens were all Arthropoda belonging to the Chironomidae (67.6%) and Halacaridae (32.4%); the numbers recorded from individual crabs ranged from 10 to 217 (av. 98 ± 76). The percentages of Chironomidae and Halacaridae on the claws of E. sinensis differed (Fig. 1b); their respective numbers varied from 6 to 163 and from 4 to 66. A significant increase in the number of epibionts with claw length was observed only in the German crabs (p < 0.05, r2 = 0.77).

Страницы:
1  2 


Похожие статьи

M Normant, J Korthals - Epibiota associated with setae on chinese mitten crab claws