The effects of competitors on fitness of marbled goby Pomatoschistus marmoratus (Pisces, Gobiidae) in the Mar Menor coastal lagoon (SE Iberian Peninsula)

Figures & data

Figure 1. Geographical location of the Mar Menor coastal lagoon and location of sampling sites.

Table I. Mean values±SD of variables in each sampling site: water temperature; water salinity; depth; submerged vegetation richness; submerged vegetation cover; submerged vegetation volume: 0 (low density) to 5 (high density); substrate size (SS; mean value); substrate heterogeneity (SH; mean value); fish species richness; potential competitor fish species abundance; potential competitor fish species biomass.

Sampling site	Water temperature (°C)	Salinity (‰)	Depth (cm)	Submerged vegetation cover (%)	Submerged vegetation volume	SS	SH	Fish species richness	Potential competitor fish species abundance (CPUEs)	Potential competitor fish species biomass (CPUEs)	P. marmoratus abundance (CPUEs)	P. marmoratus biomass (BPUEs)
La Chanta (1)	23.1±0.8	40.2±0.1	57±3	5±9	0.7±0.6	2.1±0.0	0.2±0.0	13±3	14.7±22.0	6.5±9.3	23.4±30.0	35.0±19.7
Las Brisas (2)	24.2±0.4	41.5±0.0	72±4	10±8	0.7±0.6	2.3±0.1	0.8±0.2	10±2	13.0±14.5	13.1±8.0	80.8±70.1	123.0±45.1
El Casino (3)	23.5±0.6	42.1±0.1	48±1	23±16	1.7±0.6	2.6±0.3	0.9±0.5	10±1	2.3±4.9	7.9±11.5	41.1±19.6	73.6±10.0
El Ciervo (4)	24.6±0.3	42.1±0.0	28±5	7±3	1.0±0.0	2.2±0.2	0.8±0.2	9±1	1.0±1.0	2.6±4.3	13.6±10.8	30.7±2.8
Playa Honda (5)	25.6±0.9	41.5±0.0	56±4	18±10	1.3±0.6	2.4±0.2	0.8±0.3	13±3	4.0±4.0	14.5±13.2	14.7±19.7	32.7±6.4
Los Urrutias (6)	28.2±0.6	42.7±0.2	18±1	32±23	2.7±1.5	1.9±0.3	0.8±0.1	7±1	0.0±0.0	0.0±0.0	8.3±15.7	17.7±7.3
El Carmolí (7)	23.7±0.6	33.3±1.0	22±3	9±7	1.3±0.6	1.8±0.2	0.7±0.1	8±1	1.0±1.0	0.2±0.2	25.1±57.4	6.0±17.6
Las Palmeras (8)	26.7±0.2	43.2±0.0	49±9	13±14	1.3±0.6	2.1±0.1	0.6±0.2	7±1	0.7±1.2	1.7±2.9	6.1±33.4	38.0±5.4
La Calcetera (9)	26.2±0.6	41.7±0.1	31±8	23±14	2.0±0.0	2.4±0.3	0.9±0.3	6±1	1.0±1.0	5.2±4.5	9.8±13.2	20.3±6.2

Figure 2. Size frequency distributions forPomatoschistus marmoratus and potential competitor fish species in the Mar Menor coastal lagoon.

Table II. Regression coefficients (a, b) ±SD and determination coefficients (r ²) of the log‐transformed mass–length relationship.

Sampling site	n	b (slope)	a (the y‐intercept)	Adjusted r ^2	P
La Chanta (1)	50	3.06±0.15	−10.38±0.69	0.89	<0.0005
Las Brisas (2)	38	2.81±0.20	−9.23±0.95	0.84	<0.0005
El Casino (3)	36	2.67±0.20	−8.62±0.95	0.83	<0.0005
El Ciervo (4)	32	2.52±0.24	−7.92±1.13	0.77	<0.0005
Playa Honda (5)	37	2.78±0.18	−9.10±0.81	0.87	<0.0005
Los Urrutias (6)	37	2.77±0.19	−9.07±0.88	0.85	<0.0005
El Carmolí (7)	40	2.61±0.24	−8.34±1.13	0.75	<0.0005
Las Palmeras (8)	18	2.61±0.17	−8.39±0.79	0.93	<0.0005
La Calcetera (9)	37	2.67±0.18	−8.59±0.87	0.85	<0.0005

Table III. ANCOVA analyses of the mass–length relationship in Pomatoschistus marmoratus. All variables (dependent and covariate) were log‐transformed. Total length is the covariate.

Source of variation	F	df	P
Preliminary design (test for interaction)
TL	1558.02	1, 324	<0.0005
Sampling site	0.84	8, 324	0.567
TL × Sampling site	0.87	8, 324	0.546
Final design (no interaction)
TL	1803.37	1, 324	<0.0005
Sampling site	8.95	8, 324	<0.0005

Table IV. Stepwise multiple regression model used to predict condition (a) of Pomatoschistus marmoratus from environmental variables.

	Regression equation	Adjusted r ^2	F	df	P
Model	a = −8.417 − 0.810 (potential competitor fish species abundance)	0.607	13.336	1, 8	<0.05

Figure 3. Result of the principal component analysis that includes the following variables: 1, water temperature; 2, salinity; 3, depth; 4, submerged vegetation cover; 5, submerged vegetation volume; 6, substrate size; 7, substrate heterogeneity; 8, fish species richness; 9, potential competitor fish species abundance; 10, potential competitor fish species biomass; 11, Pomatoschistus marmoratus abundance; 12, P. marmoratus biomass.