species diversity of macrobenthos in yundang lagoon ... · sara olsson w09 2012-07-13 international...

2012

International Summer Water Resources Research School Dept. of Water Resources Engineering, Lund University

Species diversity of macrobenthos

in Yundang Lagoon mangrove area,

Xiamen, China

By

Sara Olsson

Sara Olsson W09 2012-07-13 International Summer Water Resources Research School-VVRF05

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Abstract Yundang Lagoon is located in the western bay of Xiamen, China. The lagoon has moderately high levels of TOC, heavy metals and estrogenic compounds. Communities of macrobenthos provide many ecosystem services that help to maintain good water and sediment quality. The aim of this study is to know how many species of macrobenthos living in Yundang Lagoon mangrove sediment and their morphological character, density, biomass, distribution and biotic index. In June 2012, macrofauna in the inner and external lagoon mangrove sediment was investigated. The results showed that 14 species of macrobenthos were found in Yundang Lagoon mangrove sediment and on bamboo. Polychaete was the dominant group. The species composition of macrofaunal community was different in the inner and external lagoon mangrove sediment. Neanthes glandicincta was dominated in macrofaunal density in external lake mangrove sediment (85.19%) and Capitella capitata was dominated in inner lake mangrove sediment (90.95%). The biomass, species diversity index (H’) and richness index (d) in external lake were all higher than in the inner lake. AMBI (A marine biotic index) and M-AMBI showed that inner lake mangrove sediment was heavily disturbed where current hydrodynamic was poor. AMBI (A marine biotic index) and M-AMBI showed that external lake mangrove sediment was undisturbed where current hydrodynamic was good. Keywords: Macrobenthos, Yundang Lagoon, Mangrove, Species diversity, Polychaete


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Table of contents Abstract ................................................................................................................................................... 1

1 Introduction ..................................................................................................................................... 3

2 Materials and method ...................................................................................................................... 4

2.1 Field sampling ......................................................................................................................... 4

2.2 Laboratory work ...................................................................................................................... 5

2.3 Data processing ....................................................................................................................... 6

3 Results ............................................................................................................................................. 6

3.1 Species composition, density and biomass .............................................................................. 6

3.2 Biological index ...................................................................................................................... 9

3.3 Main features of common polychaete species in Yundang Lagoon ...................................... 10

4 Discussion ..................................................................................................................................... 11

4.1 Comparison of the macrofauna in the inner and external lake mangrove sediment .............. 11

4.2 Comparison species of polychaete in 2009 with 2012 .......................................................... 12

5 Conclusion ..................................................................................................................................... 12

Acknowledgements ............................................................................................................................... 13

Reference list ......................................................................................................................................... 14


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1 Introduction The water in Yundang lagoon has been negatively affected by the fast development of the downtown area of Xiamen. Mangrove trees have been planted at some locations in the lagoon for coastal zone management. The species diversity of macrobenthos in these mangroves in the inner and external lake of Yundang Lagoon will give information about the environmental status of the lagoon. Yundang Lagoon is a semi-enclosed lake situated in the north of the downtown area of Xiamen City in southeastern China. The lake has a surface area of 2.2km2. Before the 1970’s it was a natural lagoon but due to land reclamation projects it gradually turned into an enclosed and dead lagoon (Chen et al., 2010). Untreated wastewater from several thousands of residents discharged into the lagoon which became a severely polluted lagoon in the end of the 1980’s (www.Chinacitywater.org). The pollution of the lagoon aroused the attention of the public and the municipal government therefore started an environmental restoration project of the lagoon. To improve the water quality wastewater treatment plants has been set up and a tidal exchange system has been implemented to circulate fresh seawater into the enclosed lagoon (Zhang et al., 2011). The water quality has been improved (Chen et al. 2009) but recent studies show relatively high levels of TOC (Zhang, Li, Li, Wang, & Yan, 2009), heavy metals (Chen et al., 2010) and estrogenic compounds(Zhang et al., 2011) in Yundang Lagoon. Macrofauna, also called macrobenthos, are invertebrates that live on or in sediment, or attached to hard substrates. Annelid worms, bivalves, gastropods, crustaceans, tunicates, and insect larvae are the most commonly encountered macrofauna in estuarine and coastal areas. They are usually collected using 0.5 or 1 mm mesh screens. As they are visual for the eye it is a good visual indicator of the water quality. In the mangroves polychaeta is the most dominant group of macrobenthos and will therefore get the focus in this report. They have an important role in providing air and water within the soil and a key role in recycling of nutrients in aquatic systems The polychaeta is a class of annelid worms that are extremely variable in both form and lifestyle. (www.ocw.unu.edu). Together with other species and stress indicators the polychaetes could possibly be used to determine the environmental status (Pocklington & Wells, 1992). Polychaetes show sensitivity to antropogenic compounds as they live in direct contact with the water and the sediment (Pocklington & Wells, 1992). A study of diversity, abundance and distribution of polychaetes in the mangroves in Australia, shows that there are a difference in species composition in urbanized mangroves compared to undisturbed mangroves (Metcalfe & Glasby, 2008). In urbanized mangroves surface deposit feeders were more common (Metcalfe & Glasby, 2008). Many species are filter feeders and therefore get in contact with toxic compounds in the water they filter. A study of polychaetes in the English Channel point out that disturbed or temporally variable habitats tend to be occupied by species with high rates of population growth such as for example the opportunistic polychaete species Pseudopolydora pulchra and Spio decoratus (Quiroz-Martinez, Schmitt, & Dauvin, 2012). The marine environmental status can be determined using polychaetes as ecotoxicological test organisms (Pocklington & Wells, 1992). The toxicological indicators are changes in reproduction, growth, mortality and accumulation of harmful compounds. Some species of polychaete indicate certain pollution. For example H. diversicolor (Nereidae, Polychaete) can be used as bioindicator of organic contamination (Catalano et al., 2012). To be able to use polychaetes for monitoring the quality of the marine environment it is important that each country know more about its polychaetes fauna (Pocklington & Wells, 1992). The morphology is in this report studied for species identification. The most characteristic feature of the polychaete is the many bristles along the body. The name Polychaeta origins from Poly- having many and Chaeta- bristles. Another characteristic is the division of the body into similar segments. In most polychaetes additional segments are added to the body throughout their life. The majority of the polychaete species have a length of 5-10 cm and thickness of 0,2-1 cm. Many polychaetes are beautiful as they are colored red, pink, or green


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or have a combination of colors. The prey consists of small invertebrates including other polychaetes, mud and sand. Gills are common but vary in structure and location between species. The regeneration rate is fast and body parts that are ribbed off by predators are replaced rapidly. (www.ocw.unu.edu). A division of polychaetes can be made into errant (free‐moving) and sedentary forms. The sedentary polychaetes are usually tube-dwellers and live their entire life within tubes. The tubes are composed of sand grains cemented together. Based on adaptation the polychaetes can be divided into the three groups Pelagic polychaetes, Burrowing polychaetes, Tubicolous polychaetes. (www.ocw.unu.edu) The main features of the head of a polychaete are the number of eyes, peristomium cirrus, prostomial palps, and prostomial tentacles. Some main features can be observed in figure 1. If the proboscis (mouth) is taken out the jaw and paragnatha can be observed. The main features of the metastomium (body) are the three types of parapodium which are biramous (two stripes, two seta), uniramous (one stripe, one seta) and sub-biramous (two stripes, one seta).

Figure 1 Main features of Polychaeta. Source: www.ocw.unu.edu (120624)

Fouling is the accumulation of microorganisms, plants, algae and animals on wet surfaces. Together these organisms form a fouling community. In this study the fouling organisms consists of macrobenthos which are attached to branches found in the mangroves. The aim of this study is to know how many species of macrobenthos living in Yundang Lagoon mangrove sediment and to evaluate the distribution of macrobenthos in different biotopes such as planted mangroves and fouling organism communities. Samples are collected in the planted mangroves in the inner and external lake of Yundang Lagoon for comparison. The sampling data includes information about the density and biomass of the collected macrobenthos. The species richness, evenness and Shannon-Weaver’s species diversity index are determined and compared for the two sampling sites. The identification of species is done morphologically. For more accurate species identification DNA barcoding should be incorporated with morphological information. The samples were taken during one day and will not display any seasonal variation of the population.

2 Materials and method

2.1 Field sampling Samples are collected from the sediment in the planted mangroves at two different sampling sites, the inner (24°28’57’’N, 118°5’32’’E) and the external (24°28’37’’N, 118°4’36’’E) lake. Samples are taken from three locations in each site, see map in figure 2.


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Figure 2 Map of the two sampling sites, inner (left star) and external (right star) lake in Yundang Lagoon. Source: Google Earth (120706)

A spade is used to dig out, 25*25cm, sediment at each location and the sample is then collected in plastic bags. The soil and large particles (branches and rubbish) are extracted from the samples in three steps on the beach. Firstly add sea water, stir the sample in the bucket and pick out large particles. Secondly sieve the samples to remove particles smaller than 0.5mm, meiobenthos and microbenthos. Finally put the samples into plastic bottles for storage.

2.2 Laboratory work When the samples get in to the lab the samples are washed and sieved again until the washing water is clean. If there is a lot of organic matter in the samples the stain Rose Bengal (4,5,6,7-tetrachloro-2',4',5',7'-tetraiodofluorescein) can be added to stain the worms and by that make it easier to distinguish them. When pretreatment of viviperception firstly, pick out some macrobenthos from the samples carefully with a tweezer and put them in the culture dish. Secondly, add sea water into the culture dishes and put them in the fridge so that the macrobenthos won't die rapidly (if observation is going to be done in a minute, there is no need to put them in the fridge for storage). During pretreatment of specimen firstly, add 5% formaldehyde solution to all the samples so that the macrobenthos won't rotten. Secondly, pick out all macrobenthos from the samples carefully with a tweezer. Finally, put all macrobenthos into small plastic bottles and add 70% alcohol solution into them for storage. Morphological identification is done with a stereo microscope connected to a computer screen is utilized to magnify the Polychaete. From the screen the main features can be observed and the species are decided with the help of an encyclopedia of Polychaete species. It is important that the dorsal (backside) is turned upwards to be able to study the features. If the worm is lying upside down with the ventral (frontside) upwards the worm has to be flipped with a tweezer. After counting each species of macrobenthos was weighed (wet weight) on an electronic scale.


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2.3 Data processing The computer software PRIMER 5 was utilized to calculate the species richness, evenness and Shannon-Weaver’s species diversity index (log base 2). To calculate the AMBI and M-AMBI the computer software AMBI was utilized. 3 Results

3.1 Species composition, density and biomass

Figure 3 Similarity diagram for the six sampling locations at the two sites, inner and external lake.

Figure 4 Similarity-stress diagram for the six sampling locations at the two sites, inner and external lake.

The collected macrobenthos were counted, weighted and categorized into different species. The result of the density and biomass were divided with (0.25m*0.25m) to convert the unit into per square meter. The density and biomass of macrobenthos in the inner lake is presented in table 1 and the external lake in table 2.


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Table 1 Density and biomass of macrobenthos at three locations (1,2,3) in the inner lake.

Table 2 Density and biomass of macrobenthos at three locations (1,2,3) in the external lake.

In figure 5 and 6 the density and biomass of the most common macrobenthos in the inner and external lake in Yundang Lagoon are presented.

Figure 5 Mean density (%) of the most common macrobenthos in the inner and external lake.

Class Species 1 2 3 Mean 1 2 3 MeanPolychaeta Neanthes glandicincta 224 1744 880 949,3 1,31 56,1 44,6 34Polychaeta Capitella capitata 10448 16 784 3749 7,37 0 1,31 2,892Polychaeta Pseudopolydora paucibranchiata 800 32 0 277,3 2,24 0,05 0 0,764Crustacea Corophium uenoi 16 0 0 5,333 0 0 0 0,002

Density（ind/m²） Biomass（g/m²）

Class Species 1 2 3 Mean 1 2 3 MeanPolychaeta Neanthes glandicincta 160 2144 3312 1872 2,446 48,1 81,68 44,06Polychaeta Marphysa sanguinea 0 16 16 10,7 0 0,58 4,045 1,54Polychaeta Scoloplos marsupialis 0 32 0 10,7 0 0,04 0 0,015Polychaeta Chaetozone setosa 0 16 16 10,7 0 0,04 0,338 0,124Polychaeta Heteromastus filiformis 0 16 0 5,33 0 0,01 0 0,002Polychaeta Pseudopolydora paucibranchiata 64 0 48 37,3 0,053 0 0,053 0,035Crustacea Corophium uenoi 16 128 0 48 0,013 0,18 0 0,066Oligochaeta 528 0 48 192 0,23 0 0,003 0,078Crustacea Uca arcuata 16 0 0 5,33 25,05 0 0 8,35Gastropoda Lamprohaminoea cymbalum 0 0 16 5,33 0 0 0,461 0,154

Density（ind/m²） Biomass（g/m²）


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Figure 6 Mean biomass (%) of the most common macrobenthos in the inner and external lake.

The species of macrobenthos found in the fouling organism community (a bamboo branch) in the external lake is presented in table 3.

Table 3 Species of macrobenthos in the fouling organism community collected in the external lake.

The identified species of polychaete in a study done in 2009 (Study on the effect of Mytilopsis sallei on ecology and environment in Yundang Lagoon, Xiamen) and the results from this study are compiled in table 4.

Class SpeciesPolychaeta Perinereis nuntiaPolychaeta Marphysa sanguineaPolychaeta Chaetozone setosaPolychaeta Pseudopolydora paucibranchiataPolychaeta Terebella pterochaetaCrustacea Corophium uenoiBivalvia Mytilopsis sallei


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Table 4 Species of Polychaeta collected in Yundang Lagoon in 2009 and 2012

3.2 Biological index The species richness, evenness and Shannon-Weaver’s species diversity index (log base 2) are presented in table 5. Table 5 Species richness, evenness and Shannon biodiversity for the macrobenthos in the inner and external lake.

The AMBI index value ranges from 0 to 6 where 0 is interpreted as undisturbed environment and 6 as heavily disturbed environment. The M-AMBI index value ranges from 0 to 1 where 0 can be interpreted as bad ecological status and 1 as an identical match with the reference conditions. The AMBI and M-AMBI are presented in table 6.

Table 6 The biological indexes AMBI and M-AMBI and the corresponding ecological status.

Species of Polychaeta Fouling organism Sediment Fouling organism MangrovePhyllodoce malmgreni +Lepidonotus dentatus +Harmothoe lunulata +Typosyllis fasciata +Eusyllis habei + +Neanthes glandicincta + + +Perinereis nuntia + +Glycera chirori +Pseudopolydora paucibranchiata + + + +Prionospio cirrifera +Cirriformia tentaculata + +Capitella capitata + + +Marphysa sanguinea + + + +Terebella ehrenbergi + + +Potamilla torelli + +Scoloplos marsupialis +Chaetozone setosa + +Heteromastus filiformis +

2009 2012

Sampling sites Richness Evenness Shannon biodiversityInner 0,723 1,384 1,716

External 1,858 0,948 2,296

Sampling sites AMBI Status M-AMBI StatusInner lake 6,2566 Heavily disturbed 0,47401 ModerateExternal lake 0,70631 Undisturbed 0,96362 High


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3.3 Main features of common polychaete species in Yundang Lagoon Perinereis nuntia has a pear shaped prostomium, long peristomium cirrus which can reach the 3-9 ring, 2 pairs of eyes which are arranged as a trapezoid and the paragnatha is shaped as a ring, see figure 7.

Figure 7 Main features of Perinereis nuntia.

Neanthes glandicincta has 1 pair of prostomial tentacles, 1 pair of prostomial palps, 3-4 peristomiums, 2 pairs of eyes, biramous parapodium and 1 pair of jaws, see figure 8.

Figure 8 Main features of Neanthes glandicincta.


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Marphysa samguinea has 2 prostomiums and 5 prostomial tentacles, see figure 9.

Figure 9 Main features of Marphysa samguinea.

4 Discussion

4.1 Comparison of the macrofauna in the inner and external lake mangrove sediment

The polychaete species Capitella capitata and Neanthes glandicincta are the most abundant species in the inner lake and the polychaete specie Capitella capitata and Oligochaete are most abundant in the external lake. Capitella capitata has been regarded as an excellent indicator of pollution or environmental disturbance (Grassle & Grassle, 1976). A study in 2010 of the polluted Shenzhen River in Hong Kong Capitella capitata was one of the dominating species (Shen, Zhou, & Gu, 2010). While converting the results into biomass there is a noticeable change in the dominating species in the inner lake. Studying the biomass in the inner lake the Neanthes glandicincta has the greatest biomass because this worm is large compared to the other worms collected in the inner lake. In the external lake though when converting the results into biomass the crustacean specie Uca arcuata is emphasized. The reason is the heavy shell of Uca arcuata compared to the species of polychaete and oligochaete which have no shells. A study of polychaetes in the English Channel point out that disturbed or temporally variable habitats tend to be occupied by species with high rates of population growth such as for example the opportunistic polychaete species Pseudopolydora pulchra (Quiroz-Martinez et al., 2012). In the inner lake the polychaete specie Pseudopolydora paucibranchiata was the third most common specie which may indicate that the habitat in the inner lake is disturbed or temporally variable. In the fouling organism community collected at the external lake seven species of macrobenthos were found. Comparison of the fouling organism community with the species found in the mangrove samples shows that the two species of polychaetea, Perinereis nuntia and Terebella ehrenbergi, are not present in the mangrove samples. A slight difference in the distribution of species in different biotopes seems to occur. The polychaete species Neanthes glandicincta, Capitella capitata, Pseudopolydora paucibranchiata and Marphysa sanguinea were although found in all biotopes. The Shannon-Weaver’s species diversity index is slight higher in the external lake compared to the inner lake. The sampling sites are both in the planted mangrove and are located quite close to each other which may explain the similarity in species diversity of macrobenthos. In total 14 species of macrobenthos were found in Yundang Lagoon. The species


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richness in the external lake is nearly twice as high compared to the inner lake. This may be due to that fresh sea water won’t circulate and reach the inner lake so the water quality becomes bad. The few species found in the inner lake may have adapted to the water that is not exchanged often and continuously contaminated from the downtown area of Xiamen city. Macrobenthos are a good visual indicator of the water quality and a healthy ecosystem is rich in different species which is not the case for the inner lake. There is no significant difference in the species evenness between the two sampling sites. The biological indexes AMBI and M-AMBI indicate that the inner lake is heavily disturbed and the ecological status is moderate. The AMBI and M-AMBI for the external lake indicate that it is undisturbed and the ecological status is good.

4.2 Comparison species of polychaete in 2009 with 2012 A study done in 2009 (Study on the effect of Mytilopsis sallei on ecology and environment in Yundang Lagoon, Xiamen) found 15 different species of polychaete in Yundang lagoon. The sampling sites in Yundang Lagoon were not the same as in this study. In 2009 sediment samples were taken and in 2012 mangrove samples were taken. The 15 species of polychaete in 2009 can be compared to the nine identified polychaete species in 2012. There is a decrease in the species richness of Polychaete the last three years which may indicate that the water quality has not been improved in the lagoon. Some of the species found in 2009 seems to have died out, some are still present and some new species have habituated Yundang Lagoon. These three observed occurrences can be described by adaptation to a changed ecosystem. The polychaete species Scoloplos marsupialis, Chaetozone setosa, Heteromastus filiformis and Pseudopolydora paucibranchiata are new species found in 2012. These species are new in Yundang Lagoon or they might be mangrove species and thus a result of the different biotopes at the sampling sites. The polychaete species Pseudopolydora paucibranchiata and Marphysa sanguinea were found in the sediment, mangrove and fouling organism communities both in 2009 and 2012 which indicate that these two species thrive in Yundang Lagoon.

5 Conclusion The results showed that 14 species of macrobenthos were found in Yundang Lagoon mangrove sediment and on bamboo. Polychaete was the dominant group. The species composition of macrofaunal community was different in the inner and external lagoon mangrove sediment. Neanthes glandicincta was dominated in macrofaunal density in external lake mangrove sediment (85.19%) and Capitella capitata was dominated in inner lake mangrove sediment (90.95%). The biomass, species diversity index (H’) and richness index (d) in external lake were all higher than in the inner lake. AMBI (A marine biotic index) and M-AMBI showed that inner lake mangrove sediment was heavily disturbed where current hydrodynamic was poor. AMBI (A marine biotic index) and M-AMBI showed that external lake mangrove sediment was undisturbed where current hydrodynamic was good. A decrease in the number of species of polychaete in Yundang Lagoon has occurred in the last three years. The reduction in species richness point towards that the water quality has not been improved in Yundang Lagoon.


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Acknowledgements I wish to thank Professor Cai Lizhe for a well-planned project and clear instructions. Thanks to my lab assistant Zhuo Yi and research assistant Chen Xinwei for supporting me thoughout the project and all the others in the lab team that have helped me. I am also thankful for the cooperation between University of Lund and University of Xiamen and want to thank both for making the exchange possible. I would also like to thank the sponsors of this year’s International Summer Water Resources Research School: Thyréns and Xylem.


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www.Chinacitywater.org Integrated Environmental Restoration Measure and Fruits of Yun Dang Lagoon in Xiamen, (120501). www.ocw.unu.edu search word: polychaetes, Murugesan P, Ajmal Khan S, Polychaetes, Centre of Advanced Study in Marine Biology Annamalai University, (120503).

http://www.chinacitywater.org/

http://www.ocw.unu.edu/

species diversity of macrobenthos in yundang lagoon ... · sara olsson w09 2012-07-13 international...

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