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C. Bracciali et al. / Marine Environmental Research 113 (2016) 116e123 121
Table 4
Chromis chromis body shape in LOW- and HIGH-HYDRO site. In order: i) allometry by ANCOVA (a ¼ intercept; b ¼ slope); ii) descriptive statistics (mean ± s.e.) of each
morphometric trait and the coefficient of variation (CV); iii) comparison between means and T-test results.
Morphometrics -SL relationships greater in HIGH-HYDRO
Differences in angular coefficient e ANCOVA Descriptive statistics CV
Morphometrics Coefficient LOW HIGH P Mean LOW ± s.e. Mean HIGH ± s.e. LOW HIGH
Postocular distance (PostOD) b 0.13 0.17 0.0207 8.91 0.15 8.47 0.28 0.13 0.25
a 0.05 1.87 <0.0001
Predorsal length (PreDL) b 0.28 0.37 0.0003 21.25 0.31 21.49 0.57 0.11 0.20
a 0.05 1.47 0.2586
Preanal length (PreAL) b 0.62 0.69 0.0564 42.03 0.65 42.90 1.02 0.12 0.18
a 0.05 1.51 0.7510
Peduncle height (PH) a b 0.13 0.15 0.0669 9.47 0.14 9.84 0.23 0.12 0.18
a 0.01 0.01 0.0677
Differences in intercept e ANCOVA
Morphometrics Coefficient LOW HIGH P Mean LOW ± s.e. Mean HIGH ± s.e. LOW HIGH
Head length (HL) b 0.24 0.27 0.1362 17.83 0.26 17.75 0.43 0.11 0.19
a 0.03 0.38 0.0192
Jaw length (JL) b 0.08 0.06 0.2462 6.28 0.13 6.82 0.14 0.16 0.15
a 0.07 2.30 0.0041
Eye diameter (ED) b 0.06 0.08 0.0759 6.16 0.09 5.89 0.15 0.11 0.19
a 0.05 0.88 0.0004
Preocular distance (PreOD) b 0.05 0.03 0.2644 2.94 0.07 3.40 0.11 0.19 0.25
a 0.01 0.76 0.0006
Dorsal fin length (DL) b 0.56 0.51 0.1364 35.40 0.57 36.73 0.77 0.13 0.16
a 0.03 1.32 0.0310
Anal fin length (AL) b 0.17 0.15 0.2938 12.05 0.19 12.92 0.25 0.12 0.15
a 0.07 2.39 0.0001
Morphometrics -SL relationships greater in LOW-HYDRO
Differences in angular coefficient e ANCOVA
Morphometrics Coefficient LOW HIGH P Mean LOW ± s.e. Mean HIGH ± s.e. LOW HIGH
Body height (BH) b 0.28 0.20 0.0050 21.23 0.32 23.01 0.35 0.12 0.12
a 0.23 7.55 <0.0001
Pectoral fin length (PL) b 0.36 0.27 0.0003 21.37 0.38 23.45 0.42 0.14 0.14
a 0.05 3.07 <0.0001
Differences in intercept e ANCOVA
Morphometrics Coefficient LOW HIGH P Mean LOW ± s.e. Mean HIGH ± s.e. LOW HIGH
e e e e e
Morphometrics -SL relationships not significantly different between sites
Morphometrics Coefficient LOW HIGH P Mean LOW ± s.e. Mean HIGH ± s.e. LOW HIGH
Prepectoral length (PrePL) b 0.26 0.23 0.1446 18.74 0.12 19.20 0.36 0.12 0.15
a 0.11 3.04 0.5173
Ventral fin length (VL) b 0.17 0.19 0.5454 13.61 0.27 14.08 0.37 0.15 0.20
a 0.05 1.56 0.5436
Preventral length (PreVL) b 0.31 0.34 0.3388 22.05 0.34 22.24 0.52 0.12 0.18
a
P value near to the significance.
less intake of energy and characterized by morphometric traits to under quicker conditions of water current velocities. Thus, the
explain high maneuverability movements (Fulton, 2007). In morphometric traits reflecting behavioral choices, resulted in
contrast, specimens inhabiting HIGH-HYDRO sites, encountering morphological adaptations bringing an advantage under HIGH-
currents of greater intensity, could rely on higher food supply being HYDRO conditions: the fish may better control the perturbations
able to sustain greater biomass even though they should be sub- and physical disturbances coming from the surrounding water flux
jected to higher energetic costs to get food with respect to LOW- (Webb, 2002). In HIGH-HYDRO, there was more available food per
HYDRO fishes. However, overall allometric coefficients from Mar- unit of time, but individuals should be able to respond to the hy-
ettimo populations, falling well in the normal range for this species drodynamic forces and remain stable in the water column to catch
(e.g. Stergiou and Moutopoulos, 2001; Karakulak et al., 2006), prey (Sfakiotakis et al., 1999; Webb, 2002). As a main consequence
indicated that weight increments in HIGH-HYDRO were higher of this, the dorsal and anal fins and the peduncle of our C. chromis
(3.36 g per cm) than those recorded under LOW-HYDRO (about 1/3 were more developed under HIGH-HYDRO conditions. Fins are
lesser; 2.78 g per cm) suggesting that HIGH-HYDRO conditions directly employed in swimming activity, and different types of
assured greater energy supply. Interestingly, under this local hy- propulsion and swimming modes occur depending on how the fish
drodynamics, the balance between the energy required to live use them (Sfakiotakis et al.,1999; Drucker and Lauder, 2001; Pulcini
contrasting higher hydrodynamics to get food in open sites and the et al., 2008). C. chromis is described as a non-body/caudal fin-
available energy to grow appears positive. Thus, behavioral stra- locomotion species (Webb, 1994; Fulton, 2007), but it is obvious
tegies adopted by C. chromis to get energy in order to persist over that it may change locomotion mode according to the environ-
time under such environmental conditions allowed damselfish to mental variability (sensu Sfakiotakis et al., 1999). For example, in
maximize the energy intake. For example, lower body height high hydrodynamic habitats, it is more difficult to control the
observed in HIGH-HYDRO which may resemble a more fusiform pectoral fins because of their great flexibility (Drucker and Lauder,
body, is a trait to allow more performing exploitation of resources 2001), whereas longer anal fins should aid to balance pitch and yaw