Analysis of Spring Community Structure and Evaluation of Ecological Niche in Tangshan Marine Ranching, China

Abstract

To investigate the fishery community structure in spring at the early stage of construction of Tangshan Marine Ranching, in China. This study analyzed the relationship between species composition, diversity and community structure of fishery resources in marine ranching using survey data from March, April, and May 2017. The results showed that a total of 53 species of organisms occurred in the spring in the waters inside and outside the reef area of the marine pasture. Among them, 20 species of fish were among the chordates. 16 species of arthropods, including 6 species of shrimps and 8 species of crabs. Ten species of mollusks, including 6 species of snails. 5 species of echinoderms, 1 species of annelids, and 1 species of Cnidaria). The diversity index, evenness index and richness index outside the reef area of marine ranching in spring were greater than those in the reef area. According to cluster analysis and non-metric multidimensional scale ranking analysis, the biological communities inside and outside the reef area can be divided into four groups, with the similarity of the communities in the reef area being greater. The Abundance-Biomass Comparison curves (ABC curve) indicated that the biological communities within and outside of the reef had been moderately disturbed. The relative importance index and niche analysis demonstrated that there had been sufficient bait in the reef area, and the ecological structure of the marine ranching was taking shape.

1. Introduction

Recent years have witnessed a decline in the quality of aquatic products [1] due to the prevalence of disease outbreaks in aquaculture species and the abuse of fisheries drugs. Currently, the ever-increasing intensity of human fishing activities and the selection of unsuitable fishing gear have resulted in not only a gradual depletion of resources but also a significant alteration in the structure of fishery resources in many ocean regions around the world [2,3]. Artificial reefs are one option for enhancing the sustainability of aquaculture [4], which can optimize the marine environment, improve the structure of fishery resources in the sea, and reduce the amount of fishing in the sea [5]. It has been demonstrated that the scientific placement of artificial reefs and the construction of marine ranches can improve the habitat of marine biology, increase the amount of biological resources, and improve fishery yields and catch quality [6,7,8,9,10,11]. As of 2020, 136 national-level marine ranching demonstration areas have been constructed along the Chinese coast. The construction of marine ranching in China began in the early 1970s, and large-scale construction began in the early 21st century. The immediate economic benefits of marine ranching in China are estimated at 31.9 billion yuan per year, while the ecological benefits are valued at 60.4 billion yuan per year [12].

In the 1950s, Tangshan sea area in China was very rich in fishery resources, with high-quality fishing grounds such as Daqing River fishing grounds and Nanbu fishing grounds. However, in the 1970s and 1980s, due to the continuous high intensity fishing, the fishery resources gradually declined, and the main fishing species changed from Larimichthys polyactis (Bleeker, 1877), striped bass Trichiurus lepturus (Linnaeus, 1758), Paralichthys olivaceus (Temminck and Schlegel, 1846) and other higher trophic level fishes to Setipinna tenuifilis (Valenciennes, 1848), Oratosquilla oratoria (De Haan, 1844), Acetes chinensis (Hansen, 1919) and other small pelagic fishes and crustaceans with lower trophic levels and shorter life cycles [13]. In order to restore fishery resources, optimize the structure of biological communities and improve the marine ecological environment, the central and local governments of China have invested in the construction of large-scale habitat restoration projects in Tangshan sea area since the beginning of the 21st century, establishing the Laoting Marine Nature Reserve [14] and planning the construction of Tangshan Marine Ranching. Tangshan Marine Ranching is located in the northern Bohai Sea of China, one of the highest latitude marine pasture demonstration areas in China, with a unique ecological environment and historically an important habitat for Larimichthys polyactis (Bleeker,1877), Trichiurus lepturus (Linnaeus, 1758) and Paralichthys olivaceus (Temminck & Schlegel, 1846), with a significant decrease in resource density since the 1990s. artificial fish reefs began to be placed in late 2015 and took shape by late 2016. In order to comprehend the impact of artificial reefs on the structure of biological communities in the early stage of reefs construction., This study evaluated the characteristics of biological communities inside and outside the reef area, as well as the effect of the initial stage of reef construction on the structure of marine biological communities. The study of the effect of marine ranches on the structure of biological communities has garnered the interest of academics from around the world.

There are currently numerous reports on the characteristics of fishery communities in China’s various sea regions. Yu Songli et al. [15] utilized biodiversity, the ABC curve method, cluster analysis, non-metric multidimensional scale analysis, ecological niche breadth, and trophic level structure analysis to investigate the characteristics of fishery community structure and trophic level changes in the Sanmen Bay sea area. Li Tao et al. [16] studied seasonal changes in the community structure of fishery resources in the nearshore waters of the southern Shandong Peninsula using biodiversity and cluster analysis. Liu Xiuze et al. [17] studied the structure of fishery resources in the coastal waters of Liaoning Province using ecological dominance, species similarity coefficient, community diversity index, community seasonal turnover index, and migration index. Zhang Rongliang et al. [18] studied the characteristics of bottom fishery communities of artificial and natural reefs near Yantai by measuring environmental factors, biodiversity, community similarity analysis and community-environment correlation analysis. The majority of research in Tangshan ocean regions has focused on abiotic environmental analysis [19], ecological carrying capacity [20], and Simple analysis of fishery community structure [21]. However, a comprehensive analysis of the community structure and studies related to biological ecological niches in Tangshan marine ranching have not been published. This study analyzed the differences in biological community structure inside and outside the artificial reef area based on survey data collected during the early construction of Tangshan Marine Ranch in spring 2017 (March, April, and May), with the hope of contributing to the study of revealing the effects of the early construction phase of marine ranches on biological community structure.

2. Methods

2.1. Methods of Study

The biological resources survey was conducted in the months of March, April, and May of 2017, and the survey area consisted primarily of the reef area (20 stations in total) and areas outside the reef area (12 stations in total) (Figure 1). The average tidal difference in the sea is 200 cm, the maximum current speed is 36.5 cm/s, the waves are mainly wind waves, the average water depth outside the reef area is 18 m, the substrate is mud and sand both inside and outside the reef area, the water temperature varies from 0 to 25 °C throughout the year.. The majority of the survey nets consist of cage traps (with 35 mm mesh size, 10 m length, 300 mm width and 190 mm height), bottom gillnets (with 50 mm mesh size, 50 m length and 1.6 m height) and upper gillnets (with 80mm mesh size, the length of 50 m and the height of 1.4 m). The nets were taken back after 24 h.

2.2. Analytical Methods

2.2.1. Community Diversity Analysis

In this study, Shannon-Wiener index, Pielou evenness index, Margalef richness index and Pinkas relative importance index were used to analyze the biodiversity of the community, with the following formula:

Shannon Wiener diversity index (H’) analysis [22]:

$$H^{\prime }=-{\displaystyle \sum _{i=1}^{\mathrm{S}}(Pi\ln Pi)}$$

Pielou homogeneity index (J) analysis [23]:

$$\mathrm{J}=H^{\prime }/\mathrm{lnS}$$

Margalef richness index (D) analysis [24]:

$$D=(S-1)/\ln N$$

Pinkas relative importance index (|R|) analysis [25]:

$${\left|\mathrm{R}\right|=(\mathrm{Ni}+\mathrm{Wi})\times \mathrm{Fi}\times 10}^4$$

In the formula, S is the total number of species, P_i is the ratio of the number of individuals of the ith species to the total number of samples (N); N_i is the ratio of the number of the ith species to the number of all species in samples; W_i is the ratio of the ith species to all species in samples; F_i is the frequency value of the ith species at surveyed stations. When 1 ≤ H’ ≤ 3, the community is moderately disturbed; When 0 < H’ < 1, it indicates that the community is moderately disturbed [15]. If |R| ≥ 1000, it is the dominant species; if 100 ≤ |R| < 1000, it is the important species; if 10 ≤ |R| < 100, it is the common species, and if |R| < 10, it is the rare species. When H’ > 3, it indicates that the fishery biological community is undisturbed [26].

2.2.2. Community Structure Analysis

Cluster analysis was used to analyze the communities inside and outside the reef area in spring. Firstly, the biomass of the stations inside and outside the reef area was square root transformed to balance the effectiveness of rare species and also to stabilize the role of dominant species in the community. In solving the Bray-Curtis similarity coefficient matrix, non-metric multidimensional scaling (NMDS) was used for two-dimensional scale ranking and hierarchical clustering cluster to study the fishery biome structure. The results were evaluated according to the reliability of the results of non-metric multidimensional scaling analysis based on the Stress coefficient. When Stress < 0.5, it means that the ranking results are better representative; When 0.05 ≤ Stress < 0.1, the sorting result is credible; When 0.1 ≤ Stress < 0.2, it indicates that the sorting result has certain explanatory significance; When Stress > 0.2, it means that the ranking results can not correctly explain the community relationship [27,28]. In this study, primer software was used for cluster analysis.

2.2.3. Abundance Biomass Curve (ABC Curve)

This method, first proposed by Warwick in 1986, is a way to determine the degree of disturbance in a community based on the relative position of the abundance curve and the biomass dominance curve in the same coordinate system. If the biomass curve is higher than the abundance curve, the community is “undisturbed”; if the abundance curve is above the biomass curve, the community is “severely disturbed”; if the two lines basically intersect, the community is “moderately disturbed” [29]. The statistic is expressed as W by the following equation [29]:

$$\mathrm{w}={\displaystyle \sum _{\mathrm{i}=1}^S\frac{B\mathrm{i}-A\mathrm{i}}{50(S-1)}}$$

where S is the number of biological species, Bi is the cumulative percentage of biomass corresponding to species i, and Ai is the cumulative percentage of abundance corresponding to species i. if W > 0, the community is undisturbed; If W < 0, the community is disturbed; If the W value approaches 0, the community will be moderately disturbed. The closer the W value is to 1, it means that the richness of each species tends to be the same, on the contrary, the W value is close to −1.

2.2.4. Niche Breadth and Niche Overlap

The niche breadth index adopts the Shannon index [22]:

$$B\mathrm{i}=-{\displaystyle \sum _{\mathrm{j}=1}^R\left(P\mathrm{ij}\ln P\mathrm{ij}\right)}$$

Niche overlap adopts Pianka index [30]:

$$Q\mathrm{ik}={\displaystyle \sum _{\mathrm{j}=1}^{\mathrm{R}}(}PijPkj)/\sqrt{{\displaystyle \sum _{\mathrm{j}=1}^{\mathrm{R}}Pi{j}^2}{\displaystyle \sum _{\mathrm{j}=1}^{\mathrm{R}}Pk{j}^2}}$$

where P_ij is the ratio of the ith species’ abundance at station j to the total abundance at station j. P_kj is the ratio of the abundance of the kth species at station j to the total abundance at station j. B_i is the niche breadth of the ith species; The value range of B_i is [0, R], and R is the total number of stations investigated. The greater the value of B_i, the greater the niche breadth of the species, which means that the species has greater utilization of resources. When B_i ≥ 2.0, it is a wide niche species, when 1.0 ≤ B_i < 2.0, it is a medium niche species, and when B_i < 1.0, it is a narrow niche species; Q_ik represents the ecological overlap index of i species and k species, and the value range is [0,1]. The larger the Q_ik value, the stronger the similarity and inter-species competition between the i species and the k species in resource utilization. According to the classification standard of Wathne et al. (2000), the niche overlap value is divided into three levels. If Q_ik > 0.6, it means that the niche overlap degree is high; 0.3 < Q_ik < 0.6, indicating low niche overlap; Q_ik < 0.3 indicates low niche overlap [31].

3. Results

3.1. Composition Type

This spring survey uncovered a total of 53 species from distinct animal groups. 41 of which were found in the reef area, including 15 species of fish, 13 species of crustaceans and 4 species of snails. A total of 39 species were found outside the reef area, including 14 species of fish, 12 species of crustaceans, and 5 species of snails. (

Table 1. A summary of organisms inside and outside the reef area. (Note: “●” Indicates that the species has appeared in this area).

Phylum	Species Name	Within	Outside	Phylum	Species Name	Within	Outside
Chordata	Sebastes schlegelii	●	●	Arthropod	Palaemon gravieri	●	●
	Chaeturichthys stigmatias	●	●		Alpheus japonicus	●	●
	Parachaeturichthys polynema	●	●		Crangon affinis	●	●
	Hexagrammos otakii	●	●		Leptochela gracilis	●	●
	Agrammus agrammus	●			Lysmata vittata	●	●
	Chirolophis japonicus	●			Acetes chinensis	●
	Ernogrammus hexagrammus	●			Charybdis japonica	●	●
	Zoarces slongatus		●		nipponensis	●	●
	Enedrias fangi	●	●		Eucrate alcocki		●
	Tridentiger barbatus	●	●		Eucrate crenata	●
	Tridentiger bifasciatus	●			Diogenes edwardsii	●	●
	Tridentiger trigonocephalus	●	●		Dorippe japonica	●	●
	Trachidermus fasciatus	●			Xanthidae		●
	Konosirus punctatus		●		Pisidia serratifrons	●
	Platycephalus indicus		●		Oratosquilla oratoria	●	●
	Cynoglossus joyneri		●		Sphaeroma		●
	Takifugu niphobles	●	●	Mollusk	Rapana venosa	●	●
	Cynoglossus joyneri	●	●		Nassarius variciferus	●	●
	Paralichthys olivaceus	●			Nassarius siquijorensis		●
	Acanthogobius elongata		●		Glossaulax didyma	●	●
Echinodermata	Asierias rollestoni	●	●		Chlorostoma rustica	●
	Amphiura vadicola	●			Nassarius succinctus		●
	Temnopleurus hardwickii	●	●		Octopus variabilis	●	●
	Caudina similis	●	●		Octopus ocellatus	●
	Apostichopus japonicus	●			Scapharca broughtonii	●
Annelid	Nereis succinea	●	●		Leionucula tenuis		●
Cnidaria	Actiniaria		●

).

3.2. Diversity Characteristics

Following calculation, the reef area’s diversity index (

Table 2. Diversity index within and outside the artificial reef area.

Region	Shannon-Weaver Diversity Index (H’)
	X ± SD	Maximum	Minimum
within	1.34 ± 0.37	2.09	0.65
outside	1.69 ± 0.37	2.22	1.17

), evenness index (

Table 3. Evenness index inside and outside artificial reef area.

Region	Pielou’s Evenness Index (J)
	X ± SD	Maximum	Minimum
within	0.67 ± 0.13	0.86	0.45
outside	0.73 ± 0.11	0.86	0.53

) and richness index (

Table 4. Richness indexes inside and outside artificial reef area.

Region	Margalef Richness Index (D)
	X ± SD	Maximum	Minimum
within	1.62 ± 0.77	3.49	0.74
outside	2.18 ± 0.69	3.23	1.04

) can be obtained. In spring, the average value of diversity index (H’) within the reef area was 1.34, with the highest value at station JN1 (2.09), and the lowest value at station JN6 (0.65). The average value of the evenness index (J) in the reef area was 0.67, with the highest at station JN3 (0.86) and the lowest at station JN8 (0.45), The average value of the richness index (D) in the reef area was 1.62, with the highest value at the station JN1 (3.94) and the lowest value at the station JN7 (0.74). In the spring, the average value of the diversity index (H’) outside the reef area was 1.69, with the highest value (2.22 at the station JW8 and the lowest at the station JW3). Outside the reef area, the average value of the evenness index (J) was 0.73, with the highest value at the station JW4 (0.86), and the station JW3 having the lowest value (0.53). Outside the reef, the average value of the richness index (D) was 2.18, with the station JW9 having the highest value (3.23), and the station JW4 having the lowest (1.04).

3.3. Analysis of Dominant Species

Based on the analysis of the relative importance index of organisms inside and outside the reef area in

Table 5. Relative importance index of organisms in the reef area.

Species	|R|	Species	|R|
Charybdis japonica	4625.22	Alpheus japonicus	2.3
Sebastes schlegelii	4368.5	Apostichopus japonicus	2.11
Asierias rollestoni	1548.31	Tridentiger bifasciatus	1.77
Rapana venosa	1541.62	Scapharca broughtonii	1.76
Hexagrammos otakii	860.89	Agrammus agrammus	1.12
Palaemon gravieri	429.76	Leptochela gracilis	0.98
Chaeturichthys stigmatias	156.64	Acetes chinensis	0.74
Octopus ocellatus	88.23	Paralichthys olivaceus	0.61
Oratosquilla oratoria	56.05	Tridentiger barbatus	0.61
Lysmata vittata	41.44	Glossaulax didyma	0.48
Octopus variabilis	30.79	Takifugu niphobles	0.47
Enedrias fangi	12.2	Parachaeturichthys polynema	0.44
Diogenes edwardsii	8.39	Cynoglossus joyneri	0.39
Tridentiger barbatus	6.87	Trachidermus fasciatus	0.36
Chirolophis japonicus	5.64	Dorippe japonica	0.34
Ernogrammus hexagrammus	4.12	Temnopleurus hardwickii	0.31
Caudina similis	3.99	Eucrate crenata	0.29
Crangon affinis	3.76	Pisidia serratifrons	0.25
Nassarius variciferus	3.48	Amphiura vadicola	0.25
Pugettia nipponensis	3.3	Chlorostoma rustica	0.25
Nereis succinea	3.24

and

Table 6. Relative importance index of organisms outside reef area.

Species	|R|	Species	|R|
Asierias rollestoni	4614.22	Cynoglossus joyneri	8.32
Charybdis japonica	1702.12	Nassarius variciferus	6.72
Palaemon gravieri	1239.1	Octopus variabilis	5.45
Hexagrammos otakii	1074.88	Zoarces slongatus	4.66
Sebastes schlegelii	974.66	Nereis succinea	4.15
Leptochela gracilis	768.28	Nassarius succinctus	3.39
Lysmata vittata	556.38	Nassarius siquijorensis	2.76
Diogenes edwardsii	374.07	Cynoglossus joyneri	2
Chaeturichthys stigmatias	260.53	Glossaulax didyma	1.4
Crangon affinis	249.5	Leionucula tenuis	1.35
Rapana venosa	239.78	Temnopleurus hardwickii	1.29
Alpheus japonicus	233.78	Eucrate alcocki	0.93
Tridentiger barbatus	99.61	Actiniaria	0.85
Oratosquilla oratoria	69.73	Konosirus punctatus	0.84
Parachaeturichthys polynema	39.26	Dorippe japonica	0.83
Platycephalus indicus	29.08	Acanthogobius elongata	0.79
Pugettia nipponensis	23.04	Tridentiger trigonocephalus	0.76
Caudina similis	14.71	Xanthidae	0.74
Enedrias fangi	12.83	Sphaeroma	0.66
Takifugu niphobles	11.37

, there were four dominant species in the reef area of the marine ranching during the spring: Charybdis japonica (A.Milne. EdWards, 1861), Sebastes schlegelii (Hilgendorf, 1880), Asierias rollestoni (Lütken, 1871) and Rapana venosa (Valenciennes, 1846). Important species included Hexagrammos otakii (Jordan and Starks, 1895), Palaemon gravieri (Yu, 1930) and Chaeturichthys stigmatias (Richardson, 1844). Outside of the reef area, Asierias rollestoni, Charybdis japonica, Palaemon gravieri and Hexagrammos otakii were the dominant species. Sebastes schlegelii,Leptochela gracilis (Stimpson, 1860), Lysmata vittata (Johannes Govertus de Man, 1888), Diogenes edwardsii (De Haan, 1849), Chaeturichthys stigmatias,Crangon affinis (De Haan, 1849), Rapana venosa (Valenciennes, 1846), Alpheus japonicus (Miers, 1879)were eight important species.

3.4. Community Structure Analysis

After analyzing the biomass inside and outside the reef area of Tangshan marine ranching in spring, it was obtained that the closer the stations were, the greater the similarity coefficient of the stations were. As can be seen from Figure 2 and Figure 3, the spring clustering of various stations within the reef area at a 38% similarity level can be divided into four groups, Group I (JN2, JN7 and JN15), Group II (JN1 and JN3), Group III (JN16 and JN20), and Group IV consisting of the remaining 13 stations within the reef. The stations outside the reef area clustered at 35% similarity level can be divided into four groups, namely Group I (JW5, JW6, JW8 and JW9), Group II (JW10, JW11 and JW12), Group III (JW1, JW2, JW3 and JW4), and Group IV (JW7). The two-dimensional scalar ranking plots conducted inside and outside the reef area showed a Stress value of 0.12, which proved that the results of the cluster analysis performed on the stations inside and outside the reef area were indicated with some interpretative significance, and the results of their cluster analysis could also be represented by the two-dimensional scalar ranking plots (Figure 4 and Figure 5).

3.5. ABC Curve

According to the ABC curve plotted by the proportion of biomass and abundance of each species in the total catch of the two areas inside and outside the reef area of Tangshan marine ranching in spring, the biomass curve was higher than the abundance curve in the ABC curve outside the reef area; the ABC curve inside the reef area was higher than the biomass curve first, and as the species rank increases, the abundance curve intersects with the biomass curve and the biomass curve started to be higher than the abundance curve. The biomass curve started to be higher than the abundance curve. The W values inside and outside the reef area were greater than 0. The W value outside the reef area was 0.104 and inside the reef area was 0.034, which indicated that the biological communities inside and outside the reef area were moderately disturbed, with the biological communities inside the reef area being more disturbed (Figure 6 and Figure 7).

3.6. Niche Breadth

According to

Table 7. Niche breadth in the reef area.

No.	Species	Niche Breadth	No.	Species	Niche Breadth
1	Charybdis japonica	5.06	22	Chirolophis japonicus	0.13
2	Sebastes schlegelii	4.28	23	Ernogrammus hexagrammus	0.12
3	Asierias rollestoni	3.44	24	Acetes chinensis	0.11
4	Rapana venosa	2.59	25	Agrammus agrammus	0.09
5	Hexagrammos otakii	2.4	26	Apostichopus japonicus	0.08
6	Palaemon gravieri	1.46	27	Tridentiger trigonocephalus	0.08
7	Chaeturichthys stigmatias	1.01	28	Paralichthys olivaceus	0.07
8	Octopus ocellatus	0.88	29	Dorippe japonica	0.07
9	Oratosquilla oratoria	0.83	30	Takifugu niphobles	0.07
10	Lysmata vittata	0.65	31	Glossaulax didyma	0.07
11	Enedrias fangi	0.46	32	Scapharca broughtonii	0.06
12	Diogenes edwardsii	0.38	33	Leptochela gracilis	0.06
13	Crangon affinis	0.34	34	Amphiura vadicola	0.06
14	Tridentiger barbatus	0.32	35	Parachaeturichthys polynema	0.05
15	Octopus variabilis	0.25	36	Eucrate crenata	0.04
16	Nereis succinea	0.22	37	Temnopleurus hardwickii	0.04
17	Alpheus japonicus	0.22	38	Cynoglossus joyneri	0.03
18	Caudina similis	0.2	39	Trachidermus fasciatus	0.02
19	Nassarius variciferus	0.18	40	Pisidia serratifrons	0.02
20	Pugettia nipponensis	0.18	41	Chlorostoma rustica	0.02
21	Tridentiger bifasciatus	0.15

and

Table 8. The outside of the reef niche breadth.

No.	Species	Niche Breadth	No.	Species	Niche Breadth
1	Asierias rollestoni	2.73	21	Tridentiger trigonocephalus	0.16
2	Palaemon gravieri	2.73	22	Nassarius succinctus	0.14
3	Charybdis japonica	1.63	23	Glossaulax didyma	0.1
4	Hexagrammos otakii	1.6	24	Zoarces slongatus	0.09
5	Leptochela gracilis	1.48	25	Takifugu niphobles	0.09
6	Diogenes edwardsii	1.39	26	Nassarius siquijorensis	0.08
7	Lysmata vittata	1.13	27	Eucrate alcocki	0.07
8	Crangon affinis	1.12	28	Acanthogobius elongata	0.07
9	Alpheus japonicus	0.97	29	Platycephalus indicus	0.13
10	Chaeturichthys stigmatias	0.75	30	Leionucula tenuis	0.07
11	Sebastes schlegelii	0.62	31	Dorippe japonica	0.06
12	Tridentiger barbatus	0.51	32	Konosirus punctatus	0.06
13	Oratosquilla oratoria	0.49	33	Xanthidae	0.06
14	Rapana venosa	0.34	34	Temnopleurus hardwickii	0.04
15	Parachaeturichthys polynema	0.31	35	Actiniaria	0.04
16	Nassarius variciferus	0.23	36	Sphaeroma	0.04
17	Pugettia nipponensis	0.21	37	Cynoglossus joyneri	0.04
18	Caudina similis	0.19	38	Octopus variabilis	0.03
19	Enedrias fangi	0.18	39	Cynoglossus joyneri	0.02
20	Nereis succinea	0.16

, the niche width values in the reef area of Tangshan marine pasture in spring ranged from 0.02 to 5.06, with Charybdis japonica having the highest value and Trachidermus fasciatus (Heckel, 1837), Pisidia serratifrons (Stimpson, 1858), Chlorostoma rustica (Gmelin, 1928) having the lowest. There were 5 wide niche species, 2 medium ecotone species, and 34 narrow ecotone species. The niche width values in the control area outside the reef area in spring ranged from 0.02 to 2.73, with Asierias rollestoni having the largest ecotone width value and Cynoglossus joyneri (Günther, 1878) having the smallest. There were 2 brode niche species, 6 medium niche species, and 32 narrow niche species.

3.7. Niche Overlap

As shown in

Table 9. Niche overlap index of fishery resources with economic value in the reef area of Tangshan marine ranching.

NO.	A1	A2	A3	A4	A5	A6	A7	A8	A9	A10	A11	A12	A13	A15	A16	A17	A18	A19	A20	A21	A22	A23	A24
A2	0.00
A3	0.00	0.00
A4	0.09	0.02	0.00
A5	0.00	0.00	0.00	0.14
A6	0.00	0.00	0.00	0.16	0.00
A7	0.58	0.00	0.00	0.13	0.00	0.00
A8	0.01	0.87	0.00	0.03	0.00	0.00	0.16
A9	0.00	0.45	0.00	0.05	0.00	0.00	0.00	0.00
A10	0.00	0.00	0.00	0.03	0.00	0.00	0.77	0.19	0.00
A11	0.33	0.00	0.00	0.10	0.00	0.00	0.71	0.16	0.00	0.67
A12	0.00	0.89	0.00	0.00	0.00	0.00	0.00	0.98	0.00	0.00	0.00
A13	0.00	0.38	0.51	0.06	0.00	0.00	0.02	0.01	0.86	0.00	0.03	0.00
A14	0.00	0.32	0.00	0.34	0.10	0.00	0.00	0.00	0.71	0.00	0.00	0.00	0.61
A15	0.00	0.00	0.00	0.64	0.18	0.00	0.08	0.03	0.00	0.00	0.00	0.00	0.02
A16	0.00	0.31	0.21	0.20	0.09	0.59	0.03	0.01	0.69	0.02	0.02	0.00	0.70	0.07
A17	0.33	0.00	0.16	0.32	0.02	0.00	0.36	0.09	0.00	0.00	0.38	0.00	0.15	0.47	0.06
A18	0.58	0.00	0.00	0.45	0.09	0.00	0.44	0.05	0.00	0.00	0.19	0.00	0.03	0.47	0.07	0.66
A19	0.01	0.35	0.17	0.58	0.27	0.18	0.08	0.24	0.31	0.06	0.04	0.23	0.36	0.62	0.55	0.15	0.19
A20	0.00	0.00	0.00	0.49	0.15	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.41	0.10	0.00	0.58	0.30
A21	0.00	0.85	0.00	0.01	0.00	0.00	0.24	0.99	0.00	0.32	0.21	0.95	0.00	0.00	0.01	0.00	0.00	0.24	0.00
A22	0.00	0.00	0.00	0.03	0.00	0.00	0.77	0.19	0.00	1.00	0.67	0.00	0.00	0.00	0.02	0.00	0.00	0.06	0.00	0.32
A23	0.07	0.02	0.07	0.90	0.16	0.24	0.06	0.01	0.05	0.00	0.03	0.00	0.09	0.64	0.32	0.19	0.50	0.63	0.72	0.00	0.00
A24	0.00	0.00	0.00	0.26	0.00	0.69	0.13	0.05	0.00	0.00	0.00	0.00	0.03	0.28	0.49	0.56	0.40	0.17	0.00	0.00	0.00	0.26
A25	0.00	0.00	0.00	0.02	0.00	0.00	0.00	0.01	0.00	0.00	0.00	0.00	0.00	0.00	0.26	0.00	0.00	0.20	0.00	0.00	0.00	0.17	0.23

Notes: A1: Agrammus agrammus; A2: Apostichopus japonicus; A3: Glossaulax didyma; A4: Hexagrammos otakii; A5:Octopus ocellatus; A6: Cynoglossus joyneri; A7: Enedrias fangi; A8: Palaemon gravieri; A9: Temnopleurus hardwickii; A10: Paralichthys olivaceus; A11: Crangon affinis; A12: Leptochela gracilis; A13: Oratosquilla oratoria; A14: Scapharca broughtonii; A15: Ernogrammus hexagrammus; A16: Rapana venosa; A17: Chaeturichthys stigmatias; A18: Chirolophis japonicus; A19: Charybdis japonica; A20: Trachidermus fasciatus; A21: Caudina similis; A22: Takifugu niphobles; A23: Sebastes schlegelii; A24: Octopus variabilis; A25: Acetes chinensis.

and

Table 10. Niche overlap index of fishery resources with economic value outside the reef area of Tangshan marine ranching.

NO.	B1	B2	B3	B4	B5	B6	B7	B8	B9	B10	B11	B12	B13	B14	B15	B16	B17	B18	B19	B20	B21
B2	0.26
B3	0.01	0.80
B4	0.01	0.09	0.07
B5	0.00	0.05	0.03	0.76
B6	0.00	0.01	0.00	0.43	0.07
B7	0.00	0.02	0.00	0.84	0.98	0.09
B8	0.05	0.01	0.00	0.38	0.38	0.09	0.34
B9	1.00	0.25	0.00	0.00	0.00	0.00	0.00	0.02
B10	0.03	0.00	0.00	0.25	0.22	0.07	0.20	0.97	0.00
B11	0.02	0.00	0.00	0.00	0.00	0.00	0.00	0.76	0.00	0.82
B12	0.02	0.00	0.00	0.00	0.00	0.00	0.00	0.76	0.00	0.82	1.00
B13	0.03	0.00	0.00	0.09	0.04	0.01	0.04	0.87	0.00	0.92	0.96	0.96
B14	0.01	0.00	0.00	0.52	0.58	0.28	0.53	0.52	0.00	0.38	0.00	0.00	0.11
B15	0.02	0.00	0.00	0.26	0.11	0.02	0.08	0.52	0.00	0.49	0.00	0.00	0.19	0.58
B16	0.00	0.00	0.00	0.72	0.99	0.07	0.97	0.33	0.00	0.17	0.00	0.00	0.03	0.53	0.00
B17	0.00	0.00	0.00	0.48	0.90	0.07	0.81	0.34	0.00	0.19	0.00	0.00	0.04	0.57	0.00	0.92
B18	0.00	0.00	0.00	0.38	0.00	0.98	0.03	0.06	0.00	0.05	0.00	0.00	0.00	0.32	0.00	0.00	0.00
B19	0.00	0.00	0.00	0.19	0.00	0.39	0.04	0.07	0.00	0.00	0.00	0.00	0.00	0.58	0.00	0.00	0.00	0.55
B20	0.00	0.00	0.00	0.19	0.00	0.39	0.04	0.07	0.00	0.00	0.00	0.00	0.00	0.58	0.00	0.00	0.00	0.55	1.00
B21	0.00	0.00	0.00	0.32	0.00	0.88	0.00	0.02	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.77	0.00	0.00
B22	0.94	0.46	0.14	0.12	0.12	0.01	0.11	0.15	0.93	0.09	0.03	0.03	0.06	0.09	0.08	0.10	0.10	0.00	0.00	0.00	0.00

Notes: B1: Sebastes schlegelii; B2: Chaeturichthys stigmatias; B3: Zoarces slongatus; B4: Palaemon gravieri; B5: Crangon affinis; B6: Leptochela gracilis; B7: Alpheus japonicus; B8: Charybdis japonica; B9: Octopus variabilis; B10: Rapana venosa; B11: Takifugu niphobles; B12: Cynoglossus joyneri; B13: Caudina similis; B14: Platycephalus indicus; B15: Temnopleurus hardwickii; B16: Parachaeturichthys polynema; B17: Enedrias fangi; B18: Oratosquilla oratoria; B19: Glossaulax didyma; B20: Konosirus punctatus; B21: Cynoglossus joyneri; B22: Hexagrammos otakii.

, the niche overlap of fishery species inside and outside the reef area of Tangshan marine ranching in spring was uneven, and the range of Q values was [0,1]. There were 25 pairs with high overlap in the reef area, accounting for 8.33% of the total number of pairs. The largest overlap value was 1 for the group of Takifugu niphobles (Jordan & Snyder, 1901) and Paralichthys olivaceus (Temminck & Schlegel, 1846), followed by 36 pairs of medium overlap, representing 12% of the total number of pairs, 239 pairs of low overlap, representing 79.67% of the total number of pairs, and 152 pairs with no overlap. Outside of the reef area, there were 27 pairs of highly overlapping pairs outside the reef area, accounting for 11.69% of the total number of pairs, among which the overlap value of two groups of ecological niches, Takifugu niphobles and Cynoglossus joyneri, Glossaulax didyma (Azuma, 1961) and Konosirus punctatus (Temminck & Schlegel, 1846), was the largest at 1, 27 pairs with medium overlap, representing 11.69% of the total number of pairs, 177 pairs with low overlap, representing 76.6% of the total number of pairs, and 108 pairs with no overlap.

4. Discussion

4.1. Species Composition Analysis

A total of 53 species were found in the survey inside and outside the reef area, including 41 species in the reef area and 40 species outside the reef area. Among them, 30 species of swimming animals were found in the reef area and 27 species of swimming animals were found outside the reef area. Most fish were benthic and reef fish, such as Sebastes schlegelii, Hexagrammos otakii. In addition, due to its proximity to the estuary, a small number of hygrosaline fish, such as Trachidermus fasciatus, Parachaeturichthys polynema, Tridentiger bifasciatus (Steindachner,1881), etc., can appear near the estuary.

Based on the spring survey of the Tangshan sea by Duxiao et al. in 2012, the dominant spring species in the Tangshan sea were Loligo japonica (Hoyle, 1885), Crangon affinis, Oratosquilla oratoria, which were both cephalopods and crustaceans [21]. The dominant species within a reef region were Charybdis japonica, Sebastes schlegelii, Asierias rollestoni, Rapana venosa, The preponderance of waters off reefs was Asierias rollestoni, Charybdis japonica, Palaemon gravieri, Hexagrammos otakii. From the comparison of the dominant species inside and outside the reef area, the relative importance index of Asierias rollestoni in the reef area was much lower than that outside the reef area, which objectively proves that due to the construction of the marine ranching, the Asierias rollestoni, which had a significant impact on the marine biological community. The status of the more dangerous creatures was slowly declining. Meanwhile, since Charybdis japonica was the main dominant species in the reef area, this organism can provide a rich food base for the whole ecosystem. The reason for this may be that the marine ranching are still in the early stage of construction due to the enhancement of prawns, crabs and fishes, which made creatures such as Sebastes schlegelii and Charybdis japonica occupy the main position of the biome for a short period. Overall, there had been harvest from marine pasture construction, the ecological status of this pest organism like the Asierias rollestoni had improved compared to control waters off reefs, and the abundance of bait organisms like the Charybdis japonica and Palaemon gravieri species selected by r will result in an abundance of bait communities on reefs compared to off reefs control waters, And thus improved the diversity of biological communities within a reef area so that species richness is higher and community structure is more stable.

In conclusion, due to the abundance of bait organisms such as crustaceans and shrimp in marine ranching, it is recommended that the enhancement on fishes with lower trophic grade may be increased appropriately, but that the amount of enhancement should be considered in order to avoid a situation in which the number of bait organisms decreases sharply as a result of excessive release.

4.2. Biome Diversity

The indexes of diversity are important indexes characterizing the community structure, and each index is mainly influenced by natural and human factors together [32]. By comparing the diversity of biological communities inside and outside the reef area of Tangshan marine ranching in spring, it was found that the biological communities inside and outside the reef area of Tangshan marine ranching were disturbed to different degrees in spring, and the values of H’ (diversity index), J (evenness index) and D (richness index) inside the reef area were lower than those outside the reef area. This indicated that the reef community was disturbed to a higher degree, while the biological species outside the reef were richer and more equally distributed. The results of this study contradicts the findings of Clark et al. (1999) [33] and Scott et al. (2015) [34] that the values of the biodiversity index indices within the reef area are higher than those outside the reef area. The main reasons for this are the artificial disturbance factors, such as the enhancement of shrimps, crabs, fish, etc., which increase the number of proliferating species in a short period of time, making the utilization of the enhancement species higher and more widely distributed. The placement of artificial reefs had caused physical disturbances to the living environment of organisms, such as the substrate environment under the influence of the flow field from the original small particle size of the sediment substrate to rock reefs and bigger particle size of sand, and the noise generated by an excessive number of vessels during the early stages of reef development.

4.3. Characteristics of Biome Structure

By cross-referencing the results of cluster analysis with NMDS analysis, it can be seen that the stations within the reef area in spring Tangshan sea can be divided into four groups at the level of similarity coefficient of 38%; the stations outside the reef area can also be divided into four groups at the level of similarity coefficient of 35%, and the clustering results are verified and analyzed by NMDS, and the two-dimensional dot plot ranking results of NMDS Stress value is 0.12, which means that the two-dimensional dot plot of NMDS The results have some interpretative significance and are acceptable. In general, the community structure inside and outside the reef area is relatively stable, and the reason for the higher species similarity within the reef area may be due to the fact that the marine ranching is in the early stage of construction, and the species was released in the reef area, which makes the r-selected species such as Charybdis japonica in the reef area reproduce and grow rapidly in the reef area, thus leading to the higher station similarity within the reef area [35].

The analysis of the ABC curve of this study showed that W > 0 inside and outside the reef area, which has been reduced by disturbance in this sea compared to the results of Du Xiao et al. (2012) (W < 0) [21]. This result indicated that the spring Tangshan marine ranching was disturbed to a moderate degree, and lower W values in the reefs than outside indicated greater disturbance in the reefs,,which was consistent with the biodiversity analysis. The reason for this could also be attributed to the fact that marine ranching was in the early stages of construction, which had an impact on the living environment of marine species, such as the impact of noise coming from ships and the impact of oil pollution on the habitat environment of organisms within the sea.

4.4. Niche Breadth and Niche Overlap

Niche breadth represents the utilization of environmental resources by biological populations. [36] From the niche breadth analysis of this study, there were more species in the reef area with a broad niche, such as Charybdis japonica and Sebastes schlegelii, Asierias rollestoni, and Rapana venosa were also dominant species in the reef area, and Charybdis japonica did not appear only at stations JN3 and JN15. The broad niche species Asierias rollestoni and Palaemon gravieri were all dominant species outside the reef area, and Asierias rollestoni did not appear only at station JW7. But not all of broad niche species were dominant, i.e., the relative importance index is not perfectly positively correlated with niche breadth, as Hexagrammos otakii fish in the reef area were the broad niche species but not the dominant species, and Hexagrammos otakii outside the reef area were with Charybdis japonica as the dominant species but not the broad niche species.

One aspect of understanding community structure is to measure the degree of overlap in resource use by different biological species in a biome [36]. Niche overlap can be used to analytically represent the potential competitive relationship between two species in a biome and the degree of similarity in their use of the environment and resources. However, the phenomenon of overlapping ecological niches does not necessarily indicate a competitive relationship between two species, but may also be a mutually coordinated symbiotic relationship, depending mainly on the amount of resources available to the two species.

The niche overlap value of of species with economic value in the reef area ranged from 0 to 1, and the distribution was uneven, which may be because the marine ranching were in the early stage of construction and the environment was more diversified. Among them, the niche overlap value of Takifugu niphobles and Paralichthys olivaceus (Temminck & Schlegel, 1846) is the largest at 1. Takifugu niphobles is a warm-temperature offshore fish, mainly inhabiting rocky reefs and sandy bottom waters, and Paralichthys olivaceus is a cold-temperature bottom fish, inhabiting the continental shelf waters with a sandy bottom. Both species have similar habitats and feed on crustaceans and other small fishes, and both occur only once at JN20 within the reef. The reason for such a high niche overlap may be due to the high overlap of their stations and similar living habits. The distribution of the niche overlap value of of species with economic value outside a reef region ranged from 0~1, among which the overlap value of Takifugu niphobles and Cynoglossus joyneri, Glossaulax didyma and Konosirus punctatus are the largest at 1. Both Takifugu niphobles and Cynoglossus joyneri are benthic fish, and both feed on crustaceans and small fish, and both only appear at station JW5 outside the reef, and the reasons for such a high niche overlap may be the result of the high overlap of their stations and similar habits. In the group of Glossaulax didyma and Konosirus punctatus, Glossaulax didyma is a carnivore inhabiting the bottom of the intertidal zone and mainly feeds on shellfish; Konosirus punctatus is a shallow-sea fish that mainly feeds on plankton; There was no obvious similarity inhabit, and both species only appeared in the JW11 staion. The reason for the higher ecological niche overlap value could be the high station overlap rate of the two species.

The fact that two species with a niche overlap value of 0 does not indicate that they are completely independent. For instance, Agrammus agrammus and Cynoglossus joyneri feed on crustaceans within the reef area, whereas Zoarces slongatus (Kner, 1868) and Cynoglossus joyneri feed on crustaceans outside the reef area. The reason may be that the scope of the investigation is limited, and the sampling amount is related to the differences in environmental resource occupied by species.

5. Conclusions

This study showed that there were sufficient bait organisms and that the biological community was relatively stable at the beginning of the construction of Tangshan Marine Ranching. Although disturbances to the biological community may have been caused by a variety of factors at the beginning of construction, the disturbances to the biological community are gradually decreasing, indicating that the ecological engineering construction of Tangshan Marine Ranching is taking shape.

It was suggested to modify the time of fishery enhancement target species such as Charybdis japonica, Sebastes schlegelii. The original time of fishery enhancement was September every year. According to the study by Xu, X.H et al. (2010) [37], the reproductive period of Charybdis japonica is from May to September, and the suitable water temperature is 17.5–23.5 °C, and the feeding quantity increases as the water temperature rises;so it was suggested that the enhancement time is from July to August in summer [38]. Sebastes schlegelii is an ovoviviparous fish that feeds on juveniles of the same species [39]. Therefore, the fishery enhancement can be considered in the summer months of July to August after the reproductive period to avoid feeding juveniles of the same species, which can diminish the effect of fishery resource enhancement.

By modifying the enhancement time to obtain better ecological benefits, the number of target enhancement species can reach a certain commercial scale sooner, which can result in greater economic benefits; however, the amount of stocking should not exceed the enhancement carrying capacity so as not to reduce the survival rate of target species and economic benefits due to intra-species competition.