Changes in behavioural response of Mediterranean seabass (Dicentrarchus labrax L.) under different feeding distributions

Figures & data

Table 1 Description of swimming behaviours of seabass.

Behavioural categories	Behaviour description
Surface position	Fish at <3 m from surface
Middle column position	Fish at 3–5 m from surface
Horizontal swimming	Fish move parallel to surface
Swimming vs. surface	Fish move vertically toward surface
Swimming vs. bottom	Fish move vertically toward bottom
Direction change	Fish modify their swimming pathway
Collision	Physical contact between two fishes, which swimming direction was not pointed toward the other
Agonistic	Physical contact between two fishes after, at least, one of them moved with its head pointed toward the other

Table 2 Behavioural frequencies (mean ±SE) during food distribution.

		Feeding distribution
	Automatic		Manual
Behavioural events	Mean±SE		Mean±SE
Surface position	2.2±0.4		2.2±0.4
Middle column position	3.1±0.3		2.1±0.3
Horizontal swimming	35.1±0.9		26.5±1.1
Swimming vs surface	10.4±0.6	8.1±0.5
Swimming vs bottom	22.1±0.7		20.3±0.4
Direction change	16.2±0.9		30.1±0.6
Collision	8.2±0.6		9.6±0.8
Agonistic	2.7±3.1		1.1±3.4

Table 3 PERMANOVA carried out on water column position and swimming variables to test the null hypothesis of no difference between automatic and manual modes throughout different phases of the study (BEFORE, DURING, and AFTER).

		Water column position				Swimming
Source of variation	df	MS	Pseudo-F	P(perm)	MS	Pseudo-F	P(perm)
Feeding (FEED)	1	4.11	0.71	ns	609.28	13.76	^**
Period (PER)	1	30.44	3.55	^*	131.39	3.03	^**
Phase (PH)	2	42.65	4.88	^**	400.75	8.72	^**
Session	3	2.78	1.07	ns	12.04	1.17	ns
FEED × PER	1	5.55	0.69	ns	128.64	3.16	^**
FEED × PH	2	3.74	0.74	ns	38.72	0.99	ns
FEED × Session	3	1.86	0.72	ns	14.94	1.46	ns
PER × PH	2	6.70	0.97	ns	16.29	0.61	ns
PER × Session	3	1.71	0.66	ns	16.60	1.62	ns
PH × Session	6	1.67	0.65	ns	17.03	1.66	^*
FEED × PER × PH	2	0.93	0.39	ns	43.53	1.27	ns
FEED × PER × Session	3	4.18	1.61	ns	13.80	1.34	ns
FEED × PH × Session	6	0.92	0.36	ns	19.30	1.88	^*
PER × PH × Session	6	1.99	0.77	ns	13.39	1.30	ns
Day (FEED × PER × PH)	12	7.61	2.94	^**	30.10	2.93	^**
FEED × PER × PH × Session	6	1.51	0.58	ns	12.20	1.19	ns
Day (FEED × PER × PH) × Session	36	2.59	1.59	^**	10.27	1.31	^**
Residuals	288

ns = no significant difference;

* = difference at P<0.05;

** = difference at P<0.001

Figure 1 Principal coordinate analysis (PCO) of swimming behaviour comparing automatic vs manual distribution modes.

Figure 2 Principal coordinate analysis (PCO) analysis of swimming behaviour comparing automatic vs manual distribution modes in a) a.m. periods and b) p.m. periods.

Figure 3 Frequency of a) collisions and b) agonistic behaviours comparing automatic vs manual distribution modes throughout before, during and after phases (Student-Newman-Keuls [SNK] post-hoc-comparison tests are reported inside graphs.