Ecological Archives E088-189-A5

J. Wilson White and Robert R. Warner. 2007. Safety in numbers and the spatial scaling of density-dependent mortality in a coral reef fish. Ecology 88:3044–3054.

Appendix E. A summary of the 2004–2005 predator community surveys.

Mean ( ± standard error) numbers of piscivorous fish species observed on 30 × 6 m transects in surveys done in 2004 (n = 5 surveys) and 2005 (n = 7 surveys) at five study sites around St. Croix. Site abbreviations: BB = Butler Bay, NS = Northstar, CB = Cane Bay, WC = Wood Cottage, JB = Jacks Bay. WC was not surveyed in 2004.

 

Site

 

BB

NS

CB

JB

WC

Species

2004

2005

2004

2005

2004

2005

2004

2005

2005

Serranidae

                 

Cephalopholis fulva

2.88 ± 0.41

3.43 ± 0.64

4.80 ± 0.66

6.19 ± 0.32

0.38 ± 0.19

2.90 ± 0.59

0.30 ± 0.13

0.50 ± 0.19

0.46 ± 0.20

C. cruentata

0.24 ± 0.15

0.05 ± 0.05

0

0

0

0

0

0

0

Epinephelus guttatus

0

0.52 ± 0.47

0.12 ± 0.12

0.05 ± 0.05

0

0.10 ± 0.06

0.06 ± 0.06

0.11 ± 0.07

0

Serranus tigrinus

0.07 ± 0.07

0.38 ± 0.13

1.50 ± 0.21

0.90 ± 0.23

0

0.24 ± 0.14

0

0

0


Carangidae
                 

Caranx ruber

0.06 ± 0.06

0.05 ± 0.05

0.06 ± 0.06

0

0

1.40 ± 1.08

0.24 ± 0.11

1.11 ± 0.92

2.86 ± 2.86


Lutjanidae
                 

Lutjanus analis

0.03 ± 0.03

0

0

0

0

0

0

0

0

L. mahogoni

0.10 ± 0.10

0

0

0.71 ± 0.22

0.14 ± 0.09

0.52 ± 0.12

0.12 ± 0.07

0.56 ± 0.16

0.14 ± 0.10

L. synagris

0

0

0

0

0.06 ± 0.06

0

0

0

0

Ocyurus chrysurus

0

0

0

0.02 ± 0.02

0

0.05 ± 0.05

0

0.11 ± 0.07

0.19 ± 0.19


Other
                 

Bothus lunatus

0

0

0.06 ± 0.06

0

0

0

0.08 ± 0.08

0

0

Gymnothorax moringa

0

0

0

0.38 ± 0.38

0

0

0

0

0


Summary

                 

All predators

3.38 ± 0.40

4.43 ± 0.54

6.54 ± 0.80

8.26 ± 0.33

0.58 ± 0.23

5.21 ± 1.09

0.78 ± 0.15

2.39 ± 1.16

3.65 ± 2.78

Serranids only

3.20 ± 0.35

4.38 ± 0.56

6.42 ± 0.73

7.14 ± 0.48

0.38 ± 0.19

3.24 ± 0.54

0.36 ± 0.11

0.61 ± 0.16

0.46 ± 0.20

Serranids and carangids

3.26 ± 0.36

4.43 ± 0.54

6.48 ± 0.76

7.14 ± 0.48

0.38 ± 0.19

4.64 ± 1.06

0.60 ± 0.19

1.72 ± 1.01

3.32 ± 2.84

Serranids, carangids, and lutjanids
(median in parentheses)

3.38 ± 0.40 (2.7)

4.43 ± 0.54 (4)

6.48 ± 0.76 (6)

7.88 ± 0.49 (8)

0.58 ± 0.23 (0)

5.21 ± 1.09 (5)

0.72 ± 0.20 (0.6)

2.39 ± 1.16 (1.5)

3.65 ± 2.78 (1)

 

Size distribution of Cephalopholis fulva

The survey data in the above table indicate that coneys, Cephalopholis fulva, are the main consituent of the piscivore community in St. Croix. Examination of gut contents of speared coneys also confirms that they feed on juvenile bluehead wrasse (J. W. White, unpublished data). In 2003 we collected data on the size distribution of coneys at sites around St. Croix. The mean lengths at each site (± standard error) were 16.0 ± 0.9, 14.8 ± 1.0, 16.3 ± 0.9, and 18.2 ± 1.6 cm standard length at Butler Bay, Northstar, Jacks Bay, and Wood Cottage, respectively (Cane Bay was not included in this survey). Though there was a trend of slightly larger fish at sites with lower coney densities (as in 2004–2005, coney abundances were highest at Northstar and Butler Bay and lower at the other two sites), the size distributions at the four sites did not differ significantly (χ2 = 17.4, df = 15, P = 0.30). Consequently, in 2004 and 2005 we chose to streamline surveys by not recording fish length.



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