Macrobenthic Community in the Xiaoqing River Estuary in Laizhou Bay, China

LUO Xianxiang1), *, ZHANG Shanshan1), YANG Jianqiang2), 3), PAN Jinfen1), TIAN Lin1), and ZHANG Longjun1)



Macrobenthic Community in the Xiaoqing River Estuary in Laizhou Bay, China

LUO Xianxiang, ZHANG Shanshan, YANG Jianqiang, PAN Jinfen, TIAN Lin, and ZHANG Longjun

1),,266100,..2),266033,..3),,266033,..

The macrobenthic community of the Xiaoqing River Estuary and the adjacent sea waters was investigated in May and November 2008, August 2009, and May and September 2010, respectively. A total of 95 species of macrobenthos were identified in the five cruises and most of them were polychaetes (46.39%), mollusks (28.86%) and crustaceans (20.62%).The Shannon-Wiener index of macrobenthos was lower than 2 in 67% sites. Along the stream channel, estuary and the coastal waters, the species of polychaetes reduced gradually, while the abundance increased at first and then decreased. The abundance was the biggest at regions with salinity of 5-20 in the estuary. The species and abundance of mollusks and crustaceans increased gradually. As for seasonal distribution, the species, abundance and biomass were higher in spring and lower in summer and autumn.Contemporaneously compared with Laizhou Bay and Yellow River Estuary, the species of macrobenthos appeared in the Xiaoqing River Estuary were much less, while the percentage of polychaetes was higher. Abundance and biomass were higher in Xiaoqing River estuary, then consequently followed by Laizhou Bay and Yellow River Estuary. The dominant species in Xiaoqing River Estuary was polychaete, and Layzhou Bay mollusk. The community structure characteristics of macrobenthos in the Xiaoqing River Estuary revealed a significant pollution status in this region.

Xiaoqing River Estuary; Laizhou Bay; macrobenthos; community structure characteristics

1 Introduction

The Xiaoqing River springs from the northern side of Taiyi Mountain, and flows through 18 counties and urban districts of five cities in Shandong Province, China, including Jinan city, the capital of the province. It discharges into Laizhou Bay of Bohai Sea of Yangjiaogou, performing the multiple functions of drainage, irrigation and cultivation. With the social and economic development of China, it becomes one of the most polluted rivers (Zhang., 2005). Laizhou Bay is located off the southern coast of Bohai Sea;andis one of the important fishing grounds in North China and the favorite places of feeding, spawning and perch for many species ofeconomic macrobenthos. In recent years, the ecosystem health of Laizhou Bay is threatened badly by the land source pollution and marine resources exploitation. Xiao-qing River Estuary is the main pollution sources of ecological deterioration in Laizhou Bay (Zhang., 2005; Cui., 2003), and the injected pollutants has caused serious harmful impact on the estuary (Cui., 2003; Tong., 1994; Gao., 2003; Ji., 2007; Zhang., 2010; Luo., 2010).

Temporal variation in the structure and function of sediment macrobenthos communities plays a potentially central role in the ecology and biogeochemistry of continental shelves (Wheatcroft, 2006). Due to their weak abilities and relatively sessile habit,macrobenthos can properly reflect environment quality and are suitable indicators of changes in the environmental quality (Dauer, 1993;Reiss and Kröncke, 2005).In this study we conduct researches on the macrobenthos in Xiaoqing River Estuary and the adjacent aquatic regions, analyze the distribution characteristics, abundance and biomass of different species; we also investigate other neighboring waters of Bohai Sea.The results provide necessary ecological information for similar polluted estuaries, and help to assess the ecosystem health and biodiversity protection.

2 Study Area and Methods

2.1 Study Area

Macrobenthos samples were collected in the Xiaoqing River Estuary and the adjacent sea waters, Laizhou Bay, during five cruises from 2008 to 2010 (May and November, 2008; August, 2009; May and September, 2010). The collection is in dry (May), wet (August and September) and normal seasons (November). The sampling site was set up accompanying the change of salinity; the study area ranged from 37˚00′ to 37˚35′N, 118˚50′ to 119˚20′E (Fig.1): Station 1-3 were located in the stream channel, and Station 4-7 in the nearby river mouth, with the salinity ranging from 5-20, while Station 8-12 were located in the coastal waters, with the salinity > 24 (Fig.2).

2.2 Sampling Method

At each sampling station, two replicated samples were taken using a Van Veen grab of 0.05m, flushed through the 1 mm iron screen with sea water on the spot to investigate the macrobenthos. Then the obtained specimens were transferred to the sample bottles and fixed with 5% formalin (V/V). The protocols of treatment,preservation, counting and weighing,. were carried out according to the ‘Marine Survey Standard’ (General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China, 2007). The salinity of water was continually measured by portable 301 CTD.

2.3 Data Analysis

The Shannon-Wiener index (′),Species richness index () and Evenness index () were calculated by the following formulas:

Shannon-Wiener index (Shannon and Weaver, 1949)

Species richness index (Pielou, 1966)

. (2)

Evenness index (Margalef, 1968)

Whereis the total number of collected macrobenthos species in unit area,nthe number of-fold species,the total number of collected macrobenthos.

3 Results and Discussion

3.1 Community Composition and Distribution of Macrobenthos

Totally 97 macrobenthos species were identified in the five cruises from 2008 to 2010, the species mainly containing three groups: polychaetes, mollusks and crustaceans; a few other species being nemerteans, brachiopods, fishes and oligochaetes. There were 45 species of polychaetes (46.39%), 28 species of mollusks (28.86%), 20 species of crustaceans (20.62%), and other species 4.12%. Fig.3 shows the distribution and percentage composition of macrobenthos species in the Xiaoqing River Estuary. A total of 34 macrobenthos species were identified in May, 2008 (there were no macrobenthos at the first station); 29 and 20 species of macrobenthos in November and August, 2009, respectively; 50 species in May, 2010; and 28 species in September 2010. In the stream channel, river mouth and coastal waters, generally the species of polychaetesdecreasedgradually (Fig.3), while the mollusks and crustaceans increased. In the stream channel in August 2009, except a fewmollusks, there were no mollusks and crustaceans in the 3 stations. In the channel, polychaetes were mainlysp. and. Compared to the case of stream channel, in the river mouth and the coastal waters (Station 4-12), the percentage of polychaetes decreased, while mollusks and crustaceans increased. In this area, the mainly species of polychaetes were,sp.,sp.and; mainly mollusks were,and; and main crustaceans was.

There was significant positive correlation between numbers of species and salinity (=0.59,＜0.01,=41). In the stream channel, river mouth and coastal waters, the numbers of species increased gradually with increasing salinity.

Fig.3 Distribution and percentage composition of macrobenthos species (polychaetes, mollusks, crustaceans and others) in the Xiaoqing River Estuary.

Fig.4 Indices of relative importance (IRI) of macrobenthos in the Xiaoqing River Estuary from 2008 to 2010.

The top 10 macrobenthos species which occupy an important position in the Xiaoqing River Estuary is showed in Fig.4. Indices of relative importance (IRI) that integrate the information of size, quantity and distribution of macrobenthos ( Pinkas.,1971; Han., 2004)can reflect the changes of position and quantitative distribution of macrobenthos in the Xiaoqing River Estuary.

There were some differences in dominant macrobenthos species in the Xiaoqing River Estuary during different seasons (Fig.4). But in the five cruises, more than 60% of the top IRI were polychaetes.,,sp.,andappeared with high frequency.

The diversity characteristics could reflect the level of resources abundance and evenness of different species of macrobenthos. The Shannon-Wiener index (’),Species richness index () and Evenness index () for each station are showed in Fig.5. The Shannon-Wiener index of macrobenthos was lower than 2 for about 67% of sites along the stream channel and in coastal waters; the index increased gradually, while it was low in the whole study area. The species diversity of macrobenthos was quite low, and polychaetes was the main species in the stream channel. The salty and fresh water species mostly lived in the estuary where the salinity was between 5-20. The abundance and biomass of certain species had the advantages and demonstrated the significant features of study area (Zhang and Zhou, 2000). For example, in May, 2008, six species were identified at Station 4, the abundance ofreaching 18530ind.m. In the coastal waters where the salinity was over 24, the macrobenthos were the main mollusks and crustaceans; whilesix species were identified at Station 10, where the abundance ofreached 11040ind.m; In August 2009, five species were identified at Station 8, and the abundance ofreached 2560ind.m, so the diversity index was lower. There was no obvious seasonal change in diversity index (ANOVA,＞0.05，=5), the average being between 1.2 to 2.2.

Species richness index and Evenness index were less than 1. The species richness varied significantly among different seasons (＜0.05,=5), due to the significant differences of numbers of identified macrobenthos species. For example, the average number of identified macrobenthos species was four in August 2009, while that was 15 in May 2010. Evenness index was low in spring, while being high in summer and autumn, because spring is the breeding season for mot creatures, during which the the amount of some dominant species such as,sp. andincreases drastically, so the Evenness index drops in spring.

There was a very significant positive correlation between Species richness index and salinity (r=0.52,＜0.01, n=41). In the stream channel, river mouth and coastal waters, the numbers of species and species richness index increased clearly with increasing salinity, while there was no obvious correlation between Shannon-Wiener index, Evenness index and salinity. The Shannon-Wiener index and Evenness index reflect not only the numbers of species, but also the abundance of each species.

Fig.5 Diversity indices (H’, d and J) of macrobenthos, at each station in the Xiaoqing River Estuary.

3.2 Abundance Distribution Characteristics of Macrobenthos

The abundance distribution of macrobenthos is shown in Fig.6. In May 2008, the average abundance in surveyed waters was 10072 ind.m, among which the polychaetes accounted for 70.36%, andandsp. showed high abundance (2686 ind.mand 4108 ind.m, respectively); the percentage of mollusks was 29.31%, and that of crustacean was 0.22%. In November, 2008, the average abundance was 1175ind.m, among which polychaetes accounted for 92.94%,andsp.andshowed high abundance (499 ind.mand 192 ind.m, respectively); the percentage of mollusks was 4.17%, and that of crustacean was 2.13%. In August, 2009, the average abundance was 512ind.m, among which the mollusks accounted for 65.65%,showed high abundance (284 ind.m), and the polychaetes and the crustacean accounted for 24.72% and 1.30% respectively. In May, 2010, the average abundance was 4669 ind.m, in which the polychaetes accounted for 64.06%, andandshowed high abundance, reached 1174 ind.mand 1349 ind.mrespectively; the percentage of mollusks was 33.56%, and that of crustacean was 1.75%. In September, 2010, the average abundance was 338ind.m; the polychaetes accounted for 71.92%, andandsp. showed high abundance, reaching 73 ind.mand 52 ind.mrespectively; the percentage of mollusks was 21.18%, and that of crustacean was 1.48%.

For spatial distribution, the abundance of polychaetes increased at first and then decreased in the stream channel, river mouth and coastal waters. The abundance at the river mouth stations (Station 4-7) was the highest, though numbers of mollusks and crustaceans increased gradually.

Fig.6 The distribution of abundance of macrobenthos at each station in the Xiaoqing River Estuary from 2008-2010.

The seasonal variation of abundance in the Xiaoqing River Estuary was obvious. When analyzed by One-Way ANOVA, there were significant differences in abundance among the five cruises (<0.05, ANOVA,=5). So, there was seasonal fluctuation of abundance in the Xiaoqing River Estuary. The abundance in spring was higher than that in summer and autumn; the possible reason might be that in spring, most macrobenthos breed and many new individuals are recuited into the community, while in summer, with the mature of the macrobenthos community and the flourishing of the fishing activities, the numbers of mollusks and crustaceans with high economic value decrease rapidly; meanwhile the death of polychaetes with short cycle and the predation by other species in growth season, the community enters into subsided period, with the abundance being low.

3.3 Biomass Distribution Characteristics of Macrobenthos

The biomass distribution of macrobenthos is shown in Fig.7. In May, 2008, the average biomass in the surveyed waters was 527.36gm, among which the mollusks accounted for 75.15%, andcontributed to the high biomass, reaching 366.03gm. The percentage of polychaetes was 24.81%, and that of the crustacean was 0.02%. In November, 2008, the average biomass was 19.97gm. The polychaetes accounted for 55.19%,andcontributed to the high biomass, reaching 5.47gm. The percentage of mollusks was 36.13%, and that of the crustacean was 5.32%. In August, 2009, the average biomass was 312.86gm, the mollusks accounted for 77.68%, andcontributed to the high biomass of 214.18gm; the crustaceanand the polychaetes accounted for 0.13% and 0.09% respectively. In May, 2010, the average biomass was 102.68gm. The mollusks accounted for 93.49%, andandcontributed to the high biomass, reaching 55.6gmand 28.84gmrespectively. The percentage of polychaetes was 5.42%, and that of the crustacean was 0.95%. In September, 2010, the average biomass was 23.17gm. The mollusks accounted for 52.26%, andcontributed to the high biomass, reaching 10.47g m. The percentages of crustacean and polychaetes were 31.83% and 15.79% respectively.

In general, the biomass of mollusks was the highest in the Xiaoqing River Estuary, followed by those of polychaetes and crustacean. There were significant differences among the five cruises in biomass (<0.05, ANOVA,=5), demonstrating that there was seasonal fluctuation of biomass in the research area. The biomass was higher in spring than those in summer and autumn. But in August, 2009, the maximum of biomass of 2571.64gmappeared at Station 8, whereand manywere identified.

The variation of biomass was positively related to the abundance in other four cruises (except for results of cruise in May 2010). The Pearson correlation coefficients between abundance and biomass were 0.95 (＜0.01,=9), 0.97 (＜0.01,=9), and 0.96 (＜0.01,=6), representing a very significant positive correlation. In November, 2008, the correlation coefficient was 0.47 and was not significant (>0.05,= 10). The reason was that the biomass of the dominant species was not high. For example, the abundance ofsp. was as high as 3450ind.m, while its biomass was only 15.20gm, andthe highest biomass was 51.80gmforat Station 4. In May, 2010, the correlation coefficient was-0.44, representing a negative correlation, for the reason that in this cruise, though a mass ofsp.andwere identified,anddominated in the biomass.

Fig.7 Distribution of biomass of macrobenthos at each station in the Xiaoqing River Estuary from 2008‒2010.

3.4 Macrobenthos Characteristics: Xiaoqing River Estuary. Yellow River Estuary and Laizhou Bay

The comparison of macrobenthos characteristics between Xiaoqing River Estuary, Yellow River Estuary (119.03-119.52˚E, 37.33-38.03˚N) and Laizhou bay (119.03-119.83˚E, 37.17-37.60˚N) is shown in Fig.8. Overall, the species appearing in Xiaoqing River Estuary were far less than those in Yellow River Estuary and Laizhou bay in all seasons, while this value for Yellow River Estuary and laizhou bay were all 66; and for Xiaoqing River Estuary was 42. In summer, there were 56 species identified in Yellow River Estuary, 69 in laizhou bay, while only 24 in Xiaoqing River Estuary on average. And in all seasons, the polychaetes dominate all the areas, which covers about 40% in Yellow River Estuary and laizhou bay, and 50% in Xiaoqing River Estuary significantly more than that in other areas.

Abundance of macrobenthos in Xiaoqing River Estuarywas extremely high compared to other areas. In spring, the abundance in Yellow River Estuary was about 230 ind. m, Laizhou bay was 1118 ind.m, and Xiaoqing River Estuary reached 7370ind.m, far above the other waters. In summer, the abundance in Yellow River Estuary was 78ind.m, Laizhou bay was 296ind.m, and Xiaoqing River Estuary was the highest as 426 ind.m. Except for August, 2009, the polychaetes dominate, Xiaoqing River Estuary, the percentage was about 75%; the mollusks accounted for significant percentage in Laizhou bay, the percentage was about 82%; while there was no obvious dominant species in Yellow River Estuary.

Biomass of macrobenthos in Xiaoqing River Estuary was the highest, followed byLaizhou Bay, and then Yellow River Estuary. The biomass of mollusks was the highest which reached 80% in Laizhou Bay. Theandidentified in Xiaoqing River Estuary had high individual body weights, which contributed to the high biomass in this area. In Laizhou Bay,had high abandance. The abundance and biomass of economic mollusks and crustaceans of different life stages in Yellow River Estuary was lower than that in contemporaneous Laizhou Bay and Xiaoqing River Estuary, proving that the Laizhou Bay is one important fishery. Xiaoqing River located in the southwest thus was a vital breeding site. But the percentage of polychaetes was higher in this area, and the mollusks and crustaceans were far less than other waters, which may be due to the heavy pollution in Xiaoqing River Estuary.

Fig.8 Thecomparison of species number, abundance and biomass of macrobenthos with Yellow River Estuary, the middle of Laizhou Bay. a and b: the Yellow River Estuary and Laizhou Bay data were from ecological monitoring report of State Oceanic Administration People’s Republic of China in 2008 and 2009.

4 Conclusions

A total of 95 species of macrobenthos were indentified in the five cruises in the Xiaoqing River Estuary and the adjacent sea waters. The polychaetes were the dominant species. The abundance of polychaetes was the highest in the estuary, where the salinity was 5‒20. Along the stream channel, estuary and the coastal waters, the abundance of mollusks and crustaceans increased gradually. The variation tendency of biomass was related to the abundance. The diversity index was low in the whole study area. The Shannon-Wiener index was lower than 2 in about 67% sites. Comparing with Yellow River Estuary and Laizhou Bay,the species appeared in Xiaoqing River Estuary were far less, but polychaetes accounts for more than 50%.Abundance and biomass were highest in Xiaoqing River estuary. The community structure characteristics of macrobenthos in the Xiaoqing River Estuary revealed a significant pollution status.

Acknowledgements

We thank Professor Yu Zishan and his group members from College of Marine Life Science, Ocean University of China for the quantitative analysis on macrobenthos in the Xiaoqing River Estuary. This study was supported by the Open Fund of Sandong Provincial Key Laboratory of Marine Ecology and Environment ＆ Disaster Prevention and Mitigation (Grant No. 2011007) and the Major Programs of Marine Public Welfare (Grant No. 201105 005).

Cui, Y., Ma, S. S., Li, Y. P., Xing, H. Y., Wang, M. S., Xin, F. Y., Chen, J. F., and Song, Y., 2003. Pollution situation in the Laizhou Bay and its effects on fishery resources., 24 (1): 35-41.

Dauer, D. M., 1993. Biological criteria, environmental health and estuarine macrobenthic community structure., 26 (5): 249-257.

Gao, H. W., Wu, D. X., Bai, J., Shi, J. H., Li, Z. Y., and Jiang, W. S., 2003. Distributions of environmental parameters in Laizhou Bay in summer, 2000.,33 (2): 185-191.

General Administration of Quality Supervision, 2007. Inspection and Quarantine of the People’s Republic of China,,. Standards Press of China, Beijing,22-34.

Han, J., Zhang, Z. N., and Yu, Z. S., 2004. Macrobethic community structure in the southern and central Bohai Sea, China., 24 (3): 531-537.

Ji, D. W., Yang, J. Q., Gao, Z. H., and Jia, Y. G., 2007.Eutrophication assessment of the Western Sea Area in the Laizhou Bay during the low water period., 26 (1): 78-81.

Luo, X. X., Zhang, R., Yang, J. Q., Liu, R. H., Tang, W., and Yan, Q., 2010.Distribution and pollution assessment of heavy metals in surface sediment in Laizhou Bay., 19 (2): 262-269.

Margalef, R., 1968.. University Chicago Press, Chicago,111.

Pielou, E. C., 1966. Species-diversity and pattern-diversity in the study of ecological succession., 10 (2) : 370-383.

Pinkas, L, Oliphant, M. S., and Iverson, I. L. K., 1971. Food habits of albacore, bluefintuna, and bonito in California waters., 152: 1-105.

Reiss,H., and Kröncke, I., 2005. Seasonal variability of benthic indices: An approach to test the applicability of different indices for ecosystem quality assessment., 50: 1490-1499.

Shannon, C. E., and Weaver, W., 1949.. University of Illinois Press, Urbana, 117pp.

Tong, J. A., 1994.The main souree and distribution characteristies of pollutants in Laizhou Bay.,12 (4): 16-20.

Wang, Y., Liu, L. S., Liu, C. Q., Zhu,Y. Z., and Xu, H. M., 2010. Community structure characteristics of macrobenthos in the coasta seawaters of Bohai Bay in spring., 23 (4): 430-436.

Wheatcroft, R. A., 2006. Time-series measurements of macrobenthos abundance and sediment bioturbation intensity on a flood-dominated shelf., 71: 88- 122.

Zhang, Z. N., and Zhou, H., 2000.. Ocean University of Qingdao Press, Qingdao, 23-26.

Zhang, L. J., Xia, B., Gui, Z. S., and Jiang, C. B., 2007. Contaminative conditions evaluation of sixteen main rivers flowing into sea around Bohai Sea, in summer of 2005., 28 (11): 2409-2415.

Zhang, L. J., Sun, Q. Z., and Luo, X. X., 2010. Discussion on the high nitrite phenomenon in the Xiaoqing River Estuary in spring., 40 (2): 111- 116.

(Edited by Ji Dechun)

10.1007/s11802-013-1955-9

ISSN 1672-5182, 2013 12 (3): 366-372

. Tel: 0086-532-66782823 E-mail: lxx81875@ouc.edu.cn

(March 5, 2012; revised December 8, 2012; accepted December 23, 2012)

© Ocean University of China, Science Press and Springer-Verlag Berlin Heidelberg 2013