Spatial Niche Breadth and Overlap of Main Nekton Species in

Autumn Near Dongtou Island

Dongrong Zhang

1,2*

, Lihong Chen

, Hengtao Xu

, Weihua Feng

, Zhifu Wang

, Ling Peng

and Jian Qian

Key Laboratory of Engineering Oceanography, Second Institute of Oceanography, MNR, Hangzhou, China

State Key Laboratory of Marine Geology, Tongji University, Shanghai, China

Keywords:

Spatial Niche Breadth, Niche Overlap, Nekton Species, Dongtou Island.

Abstract: As the basic theory in community ecology, research on the niche breadth and niche overlap is of great

significance to understand the position, function of various species and explain the mechanism of interspecific

coexistence and competition. We found the main nekton were 5 species of fish, 5 species of shrimp and 2

species of crab in autumn in the sea area near Dongtou Island (DTI). The dominant species are mainly

Harpodon nehereus, Portunus trituberculatus and Oratosquilla oratoria, in which the Harpodon nehereus

and Portunus trituberculatus had the high degree of aggregation phenomenon in DTI. The niche breadth of

main nekton ranged from 1.08-2.06, and the broad niche species were shrimp Solenocera crassicornis (2.06)

and fish Harpodon nehereus (2.03), which is negative correlated with the index of aggregation intensity. The

niche overlap index (Q

) of main nekton were 66 pairs of species, in which, 32 pairs whose overlap indices

were Q

> 0.6 and 23 pairs whose overlap indices were 0.6 ≥ Q

≥0.3. The niche breadth and overlap of main

nekton communities were highly positive correlated. The niche overlap may be a necessary factor for

interspecific competition between the nekton species. The competition among species may also be affected

by the distribution and supply of resources in the coexistence area. The habitat homogenization of nekton

community should be considered in studying the niche and ecological restoration.

1 INTRODUCTION

The niche theory was first proposed and defined by

Grinnell (1917; 1924), and then Elton (1927) and

Hutchinson (1991) successively put forward

nutrition niche, multi-dimensional super volume

niche and other theories, which improved and

developed the niche theory. The niche theory has

been widely used in the study of species community

structure and function, community interspecific

relationship, biodiversity and other aspects. The

division of trophic level, functional group and niche

has been highly applied to the study of aquatic

ecosystem (especially in marine ecosystems) in

recent years. Yu et al. (2010) showed that niche

breadth could more comprehensively reflect the

evenness and change of species biomass at different

scales in the central and southern Yellow Sea; Li et

al. (2013) believed that the niche of dominant fish

species in the Yangtze River Estuary and adjacent

waters had obvious seasonal variation and spatial

movement trend. Li et al. (2017) found that the niche

overlap is different among species and has the

relatively independent distribution characteristics in

Wenzhou Bay.

Dongtou Island (DTI) is rich in islands and

marine resources, which is located in the estuarine

area (Oujiang) in the southeastern part of the East

China Sea. The sufficient baiting food brought by

river runoff supply for nekton to feed, spawn, breed

here (Day et al., 2012). There may be overlap and

interspecific competition in the niche of main nekton

species. Therefore, it is necessary to study the niche

of main nekton in estuarine waters. The research on

the nekton in Oujiang Estuary (near DTI) and its

adjacent waters mainly focused on the community

composition, community structure and its

relationship with environmental factors (Xu, 2008,

2009; Yan et al., 2018, 2019). And, Li et al. (2013)

studied the niche and interspecific association and

functional group of major nekton in the spring of

Wenzhou Bay. Zhang et al. (2019) found the niche

breadth values differed greatly and showed

1268

Zhang, D., Chen, L., Xu, H., Feng, W., Wang, Z., Peng, L. and Qian, J.

Spatial Niche Breadth and Overlap of Main Nekton Species in Autumn Near Dongtou Island.

DOI: 10.5220/0011508000003443

In Proceedings of the 4th International Conference on Biomedical Engineering and Bioinformatics (ICBEB 2022), pages 1268-1272

ISBN: 978-989-758-595-1

significant positive correlation with IRI in Yueqing

Bay. However, there is no relevant report on the

niche breadth and overlap of main zooplankton

species in autumn in the sea area around DTI.

This paper studied the niche breadth and

overlapping characteristics of the main nekton

communities in the coastal waters of DTI in autumn,

which can objectively reflect the interspecific

relationship and community structure characteristics

of the main nekton communities in the coastal

waters, reveal the ecological relationship between

different species, avoid interspecific competition due

to lack of common resources, and maintain

ecological balance. The purpose is to provide

scientific basis for the research and sustainable

utilization of the marine ecosystem.

2 MATERIALS AND METHODS

2.1 Study Area

DTI is located in the southeast coast of the East

China Sea, whch is rich in marine resources and has

many bay shorelines, and is the second largest fishing

ground in Zhejiang (Fig. 1). As the second largest

river in Zhejiang Province, the Oujiang River feeds

fresh water into the sea near DTI all year round,

making the sea rich in bait organisms, which is

favorable for fish and other nekton to feed and spawn

here.

Figure 1: Study area and sampling stations in DTI, China.

2.2 Sample Collection and Data

Analysis

The research data was collected through the survey

cruise with 10 sampling sites in Autumn (October) of

2019 in the waters around DTI (Fig. 1) (Zhang et al.,

2021). We employed an 8-m wide, mouth-opening

bottom trawl, with 20 mm cod-end mesh, was towed

in mean speed of 3.7 kn for 25 min on average in

stepped tows to collect samples. And, we

standardized the original survey data of nekton

before data analysis.

The dominant species was determined by the

Index of Relative Importance (IRI): IRI = (W + N) ×

F (1) (Pinkas et al., 1971). W is the percentage of a

species' biomass in the total biomass, N is the

percentage of a species' abundance in the total

abundance, F is the frequency of a species'

occurrence in all stations. The species with IRI＞

1000 were the dominant species; The species with

IRI value of 100-1000 were important species. We

selected the species with IRI＞100 and the frequency

of occurrence higher than 50% as the main nekton of

the study.

The aggregation intensity of main nekton species

was determined by the clumping index : I = S

/x － 1

(2); and mean crowding index : x* = (S

－

x + x

)/ x

(3) (x is the mean of the total number of species, S

the variance) (Lloyd, 1967).

The niche breadth was calculated by Shannon

Wiener index (Shannon and Wiener, 1963):

𝐵



−

∑

𝑃



𝑙𝑛𝑃









(4). According to the value of

, species can be divided into broad niche species

≥2.0), medium niche species (2.0>B

≥1.0) and

narrow niche species (1.0>B

>0) (Doledec et al.,

2000). The niche overlap index was calculated by

Pianka index (Pianka, 1973):

𝑄



∑

𝑃



𝑃



/



∑

𝑃







∑

𝑃











(5). r is the

number in all sampling station; P

and P

represent

the proportion of individual number of species i and

species k in station j to the total number of species. B

is the niche breadth with the value range in 0˗r. The

peak B

value means the high niche breadth. Q

represents the niche overlap value with the range in

0˗1. Q

> 0.3 is regarded as significant overlap, and

> 0.6 is regarded as highly significant overlap

(Krebs, 1999).

3 RESULTS & DISCUSSION

Our results showed that the main nekton in the sea

area near DTI included 5 species of fish (Harpodon

nehereus, Coilia nasus, Takifugu xanthopterus,

Chrysochir aureus, Collichthys lucidus), 5 species of

shrimp (Solenocera crassicornis, Palaemon gravieri,

Exopalaemon carinicauda, Oratosquilla oratoria,

Exopalaemon annandalei) and 2 species of crab

(Charybdis japonica, Portunus trituberculatus) in

Spatial Niche Breadth and Overlap of Main Nekton Species in Autumn Near Dongtou Island

1269

autumn (Table 1). The dominant species are mainly

Harpodon nehereus, Portunus trituberculatus and

Oratosquilla oratoria. As the aggregation intensity

of dominant species is an indicator reflecting the

spatial distribution of nekton. When it is positive, it

means that the spatial pattern of the species is non-

random to a greater extent, i.e. there is a certain

aggregation, and the high positive value means the

high aggregation intensity. We found that the

Harpodon nehereus and Portunus trituberculatus

were captured in the all sampling stations, implied

that there is a large number of aggregation

phenomenon of these two species in the sea area,

which also can be reflected from the aggregation

intensity index (Table 1).

Comparison with the aggregation intensity index,

the spatial niche reflects the evenness of species

spatial distribution (Yu et al., 2010), and it is a

negative correlated with the index of aggregation

intensity (I, x*). For instance, Portunus

trituberculatus and Oratosquilla oratoria were the

relatively low niche species, while their indices of

aggregation intensity (I=15342.02, 15771.32;

x*=20701.22, 20763.66) were extremely high (Table

1, Fig. 2). As the niche theory is one of the basic

theories to explain the mechanism of interspecific

coexistence and competition in communities. The

calculation of niche breadth and niche overlap is of

great significance to understand the position and

function of various species in the community and the

relationship among species (Yu et al., 2010; Zhang et

al., 2019). Niche breadth is an important index to

evaluate the environmental adaptability and resource

utilization of species, and its value depends on the

ecological adaptability, interspecific competitiveness

and distribution range of species (Soberon and

Peterson, 2005). We found that the niche breadth of

main nekton ranged from 1.08-2.06 in DTI (Fig. 2).

The broad niche species were shrimp Solenocera

crassicornis (2.06) and fish Harpodon nehereus

(2.03), while other species were the medium niche

species. The niche breadth segmentation is not

obvious, contrary to Zhang et al (2020). The larger

the value of niche breadth, the higher the ability of

the species to use its resources, and the species could

more easily adapt to environmental changes and

broadened the scope of activities (Liu et al., 2018).

The niche breadth of Harpodon nehereus was

relatively high (2.03) with the high proportion of

quantity (Table 1), indicated the species has the

widest distribution and is more adaptable to

environmental changes, able to make better use of

environmental resources and at an absolute

advantage in the competition in the investigated sea

area.

The overlap value of ecological niches reflects

the similarity and competition between species for

the utilization of same resource (Liu et al., 2018;

Wathne et al., 2000). When the overlap value was

greater than 0.6, the overlap between species pairs

was significant, and the overlap between species

pairs and stations was high (Wathne et al., 2000). In

the sea area near DTI, the results indicated the niche

overlap index (Q

) of main nekton were 66 pairs of

species, in which, 32 pairs whose overlap indices

were Q

> 0.6 (accounting for 48.48% of the total

species pairs) and 23 pairs whose overlap indices

were 0.6 ≥ Q

≥0.3 (accounting for 34.85% of the

total species pairs), and only 11 pairs whose overlap

indices were < 0.3

(accounting for 16.67% of the total

species pairs) (Table 2). The niche breadth and

overlap of the main nekton communities were highly

positive correlated (Fig. 2, Table 2). For example, the

broad niche species shrimp Solenocera crassicornis

and fish Harpodon nehereus were significantly

overlapped with most species. Actually, niche

overlap may be a necessary factor for interspecific

competition between the nekton species. For

instance, the niche overlap of crab Portunus

trituberculatus and fish Collichthys lucidus is

significant (Q

= 0.99) (Wathne et al., 2000),

although there are some differences in the habitats

between sub-benthic Collichthys lucidus and benthic

Portunus trituberculatus, their competition in food

resources is fierce as they both feed on benthos.

Nevertheless, the niche overlap of Solenocera

crassicornis and Exopalaemon annandalei is not

significant (Q

= 0.18), due to the fact that the

feeding spectrum of Solenocera crassicornis are

more than that of Exopalaemon annandale. As a

result, we believed the overlap value and competition

degree of interspecific pairs are not necessarily

positive correlated. The competition among species

may also be affected by the distribution and supply

of resources in the coexistence area. Furthermore, the

high spatial niche overlap in this study also reflects

the reality of the high degree of habitat homogeneity

in the nekton community in DTI, which should be

considered in ecological restoration.

ICBEB 2022 - The International Conference on Biomedical Engineering and Bioinformatics

1270

Table 1: The Index of Relative Importance (IRI), index of aggregation intensity of main nekton species in DTI.

Nekton species Code N W F IRI I x*

Solenocera crassicornis SC 3.75 0.24 90.00 359.25 365.82 1438.97

Harpodon nehereus HN 29.77 19.93 100.00 4970.16 4918.26 13432.16

Charybdis japonica CJ 2.01 2.52 90.00 407.29 900.78 1474.41

Coilia nasus CN 1.36 4.19 80.00 443.99 480.45 869.97

Palaemon gravieri PG 1.93 0.14 70.00 145.01 784.42 1336.05

Takifugu xanthopterus TX 0.95 1.46 70.00 169.37 436.10 709.15

Exopalaemon

inicauda

EC 1.87 0.38 70.00 157.84 1065.73 1601.38

Chrysochir aureus CA 1.34 1.35 60.00 161.66 1001.63 1384.85

Portunus trituberculatus PT 18.74 19.29 100.00 3803.04 15342.02 20701.22

Oratosquilla oratoria OO 17.46 7.34 80.00 1984.02 15771.32 20763.66

Collichthys lucidus CL 4.45 4.72 60.00 550.33 5586.78 6858.89

Exopalaemon

annandalei

EA 2.17 0.07 70.00 156.53 3191.12 3810.50

Figure 2: Variation of niche breadth of main nekton species in DTI. The codes are same to Table 1.

Table 2: Niche overlap index of main nekton species in DTI. The codes are same to Table 1.

CA CL S

PG E

OO EA CJ P

1.00

0.88 1.00

0.52 0.54 1.00

CA 0.56 0.34 0.24 1.00

CL 0.82 0.73 0.37 0.46 1.00

0.83 0.78 0.70 0.45 0.46 1.00

PG 0.76 0.75 0.62 0.20 0.81 0.64 1.00

0.75 0.70 0.40 0.34 0.68 0.75 0.85 1.00

OO 0.82 0.66 0.39 0.60 0.96 0.52 0.78 0.74 1.00

EA 0.27 0.40 0.08 0.54 0.25 0.18 0.18 0.14 0.20 1.00

CJ 0.68 0.35 0.41 0.85 0.57 0.61 0.44 0.56 0.75 0.12 1.00

0.83 0.70 0.38 0.52 0.99 0.48 0.78 0.66 0.98 0.22 0.65 1.00

CONCLUSIONS

The main nekton in the sea area near DTI included 5

species of fish, 5 species of shrimp and 2 species of

crab in autumn. The dominant species are mainly

Harpodon nehereus, Portunus trituberculatus and

Oratosquilla oratoria, in which the Harpodon

nehereus and Portunus trituberculatus had the high

degree of aggregation phenomenon in the sea area.

The niche breadth of main nekton ranged from 1.08-

2.06, and the broad niche species were shrimp

Solenocera crassicornis (2.06) and fish Harpodon

2,06

2,03

1,73

1,72

1,64

1,63

1,45

1,37

1,28

1,21

1,17

1,08

0,00

0,50

1,00

1,50

2,00

2,50

Niche breadth

Main nekton species

Spatial Niche Breadth and Overlap of Main Nekton Species in Autumn Near Dongtou Island

1271

nehereus (2.03), which is negative correlated with

the index of aggregation intensity. The niche overlap

index (Q

) of main nekton were 66 pairs of species,

in which, 32 pairs whose overlap indices were Q

0.6 and 23 pairs whose overlap indices were 0.6 ≥ Q

≥0.3. The niche breadth and overlap of the main

nekton communities were highly positive correlated.

The niche overlap may be a necessary factor for

interspecific competition between the nekton

species. The competition among species may also be

affected by the distribution and supply of resources

in the coexistence area. Next, we should consider the

habitat homogenization of nekton community in

studying the niche and ecological restoration.

ACKNOWLEDGMENTS

The authors are grateful to National Natural Science

Foundation of China (Grant number 41776119) for

the financial support.

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