Zooplankton of Mangrove Tidal Creek in Myeik Coastal Zone · Zooplankton of Mangrove Tidal Creek in...

Universities Research Journal 2011, Vol. 4, No. 2

1. Demonstrator, Department of Marine Science, Mawlamyine University. 2. Pro-Rector, Dr., Mawlamyine University.

Zooplankton of Mangrove Tidal Creek in Myeik Coastal Zone

Khin May Chit Maung1 and Htay Aung2

Abstract Zooplankton samples were collected from mangrove-lined tidal creek waters in Myeik coastal zone from monthly June 2010 to March 2011. A total of 82 zooplankton species were found from a single collection site near Masan-pa Village. Among zooplankton groups, copepod ranked first in abundance and dominated 85.9% of the total monthly- samples. Protozoa and Protochordata were the second and third dominant groups of zooplankton and constituted as 4.9% and 2.1%, respectively. A classified list of zooplankton from Masan-pa tidal creek was presented. Zooplankton abundance varied in monthly samples, ranging from 1798.99 no/m3 to 4000 no/m3.

Keywords: Abundance, classification, diversity, zooplankton.

Introduction Zooplankton is small drifting animals that can be found in all water

bodies together with phytoplankton. Although the members of zooplankton represent almost every animal phylum, they are generally characterized by two major forms: holoplankton (permanent plankton) and meroplankton (temporary plankton). The groups of zooplankton are herbivores, carnivores or omnivores on the basis of diets. In the food web of marine ecosystem, zooplankton serves an essential role as an intermediate link between primary producers and secondary consumers. Through their consumption and processing of phytoplankton, zooplankton is the dominant producers of the oceans pelagic realm. Aggregation or dispersion of zooplankton population and their abundance may be correlated generally with the bloom and patchiness in phytoplankton distribution which in turn related with physical processes that control nutrient availability, temperature, light and transparency. The rich abundance of zooplankton in regions is the prime factor influencing to support high abundance of fish larvae with rapid growth rate, which will in turn become productive fishery grounds.

This study attempted to find out what kinds of zooplankton species abound in mangrove-lined water way. The Masan-pa tidal creek in mangrove-estuarine ecosystem of Myeik coastal zone is a highly variable

Universities Research Journal 2011, Vol. 4, No. 2 332

environment due to strong tidal influence. Because of well connection with the marine open sea, there is rhythmic ingress and egress of marine plankton through inflow and outflow of water. No published account is available on the monthly and seasonal distribution of zooplankton from this important mangrove waters. It is aimed to investigate the diversity and abundance of Masan-pa tidal creek.

Materials and Methods

Study area Zooplankton samples were monthly collected at Masan-pa station

which is located in nearshore mangrove waters of Myeik coastal zone from June 2010 to March 2011. The sampling station is sited in mangrove ecosystem, 5 km away from the south-west of Myeik (Fig.1).

Fig. 1. Location of zooplankton sampling station

Sampling procedures and analytical methods Zooplankton net (30cm in mouth diameter, 100 μm in mesh size and

110 cm in length) was horizontally towed with moderate speed which make the net up and down in the water. All samples concentrated in the plankton net bucket were transferred into the bottle and fixed in 2% seawater-formalin in the field. Seawater salinity and temperature at sampling site were recorded. Samples were examined under the compound microscope for identification and counting, and photographic records were also made. This study followed the classification system used by Davis


(1955), Newell & Newell (1973), Wickstead (1965), Shirota (1966), Yamaji (1971), Kasturirangan (1963), Han Shein (1975), Aung Kyi (1976), Gayder Kittim Ku (1979) and Htay Htay Mon (2009).

The abundance of zooplankton was estimated by species-wise counting, and shown the number of individual per m3 of water as zooplankton standing stock through the net. The volume of water filtered by plankton net was estimated as follow:

V= ð r2 d

In the formula, V is the volume of water filtered by net

r is the radius of the hoop of the net and

d is the length of the water column transverse by the net (Goswami, 2004).

Results In the present study, a total of eighty-two zooplankton species were identified (Table 1). The zooplankton species were found to be highest in March with 48 species, followed by November (47 species), and January (44 species). The occurrence of zooplankton in December was the lowest in the present study (Fig. 2a). Table 3 shows monthly surface temperature and salinity values of Masan-pa waters from June 2010 to March 2011. The surface temperature of mangrove-lined tidal water was found to be fairly consistent and ranged between 27 °C and 29 °C (Fig. 3b). The monthly variations of salinities were ranged from 23‰ to 28‰ (Fig. 3a).


Table 1. A classified list of identified zooplankton species from Masan-pa tidal creek.

Phylum Class Order Family Genus Sr. No

Species

Protozoa Ciliata Tintinnida Tintinnididae Tintinnopsis 1 Tintinnopsis radix (Fig.4)

Cyttarocylidae Favella 2 Favella Taraikaensis (Fig.5)

Sarcodina Foraminifera Globigerinidae Globigerina 3 Globigerina sp I (Fig.6)

4 Globigerina sp II (Fig.8)

Arthracanthida Acanthometridae Acanthometron 5 Acanthometron sp (Fig.9)

Coelenterata Hydrozoa Siphonophora Muggidae Muggiaea 6 Muggiaea atlantica (Fig.7)

Diphyldae Diphyes 7 Diphyes sp 1 (Fig.11)

Chaetognatha Sargittoidea Sagittoidae Sagittidae Sagitta 8 Sargitta enflata (Fig.12)

Arthrpoda Crustaceae Ostracada Cypridinidae Pyrocypris 9 Pyrocypris sp. 1 (Fig.10)

Eucopepoda Calanidae Nannocalanus 10 Nannocalanus minor (Fig.14)

Canthocalanus 11 Canthocalanus pauper (Fig.13)

Eucalanidae Eucalanus 12 Eucalanus attenuates (Fig.16)



Species

Arthrpoda Crustaceae Eucopepoda Eucalanidae Eucalanus 13 E. subcrassus (Fig.15)

14 E. monachus (Fig.17)

15 E. crassus (Fig.19)

Paracalanidae Paracalanus 16 Paracalanus parvus (Fig.18)

17 P. aculeatus (Fig.20)

18 P. crassirostris (Fig.21)

Acrocalanus 19 Acrocalanus gracilis (Fig.22)

20 A. gibber (Fig.23)

21 A. similis (Fig.24)

Euchaetidae Euchaeta 22 Euchaeta concinna (Fig.(25)

Centropagidae Centropages 23 Centropages furcatus (Fig.26)

Arthrpoda Crustaceae Eucopepoda Centropagidae Centropages 24 Centropages tenuiremis (Fig.27)

25 C. dorsipinatus (Fig.28)



Species

26 C. yamadai (Fig.29)

Pseudocalanidae Pseudodiaptomus 27 Pseudodiaptomus aurivilli (Fig.30)

28 P. hickmani (Fig.31)

Temoridae Temora 29 Temora turbinata (Fig.32)

Arietellidae Metacalanus 30 Metacalanus aurivilli (Fig.33)

Pontellidae Calanopia 31 Calanopia elliptica (Fig.34)

32 C. aurivilli (Fig.35)

33 C. thompsoni (Fig.36)

Labidocera 34 Labidocera acuta (Fig.37)

Arthrpoda Crustaceae Eucopepoda Pontellidae Labidocera 35 L. pectinata (Fig.38)

36 L. minuta (Fig.39)

37 L. pavo (Fig.40)

38 L. kroyeri (Fig.41)

39 L. euchaeta (Fig.42)



Species

Pontella 40 Pontella danae (Fig.43)

Pontellopsis 41 Pontellopsis scotti (Fig.44)

Acartiidae Acartia 42 Acartia negligens (Fig.46)

43 A. danae (Fig.49)

44 A. erythraea (Fig.45)

45 A. spinicauda (Fig.48)

46 A. centrura (Fig.47)

Arthrpoda Crustaceae Eucopepoda Tortanidae Tortanus 47 Tortanus forcepatus (Fig.50)

Oithonidae Oithona 48 Oithona spinirostris Claus (Fig.51)

49 O. rigida (Fig.53)

50 O. brevicornis (Fig.52)

51 O. simplex (Fig.54)

52 O. nana (Fig.55)



Species

53 O. similis Claus (Fig.56)

Oncaeidae Oncaea 54 Oncaea venusta (Fig.57)

Lichomolgidae Kelleria 55 Kelleria regalis (Fig.58)

Corycaeidae Corycaeus 56 Corycaeus speciosus (Fig.59)

57 C. catus (Fig.60)

58 C. andrewsi (Fig.61)

Arthrpoda Crustaceae Eucopepoda Ectiosoonidae Micorsetella 59 Microstella norvegica (Fig.62)

60 M. rosea (Fig.63)

Clytemnestridae Clytemnestra 61 Clytemnestra scutellata (Fig.64)

62 C. rostrata (Fig.65)

Tachiddidae Euterpina 63 Euterpina acutifrons (Fig.66)

Harpacticoidae Tigriopus 64 Tigriopus sp.1 (Fig.67)

Amphipoda Oxycephalidae Tulbergella 65 Tulbergella cuspidati (Fig.69)



Species

Decapoda Luciferidae Lucifer 66 Lucifer penicillifer (Fig.71)

Mollusca Gastropoda Heteropoda Atlantidae Atlanta 67 Atlanta sp (Fig.70)

Protochordata Urochordata Appendicularia Oikapleuridae Oikopleura 68 Oikopleura cophocerca (Fig.68)

Annelida Polychaeta 69 Trochophore larva I (Fig.72)

70 Trochophore larva II (Fig.73)

Arthropoda Crustacea Pontellidae Pontellid 71 Pontellid nauplius (Fig.74)

Balanoides 72 Cirriped cypris larva (Fig.76)

73 Cirripede nauplius (Fig.75)

74 Brachyuran zoea I (Fig.77)

75 Brachyuran zoea II (Fig.79)

76 Brachyura megalopa (Fig.78)

Mollusca Pelecypoda 77 Bivalve larva (Fig.80)

Gastropoda 78 Gastropod larva (Fig.81)



Species

Echinodermata Ophiuroidea 79 Ophiopluteus larva I (Fig.82)

80 Ophiopluteus larva II (Fig.83)

Chordata Osteichthyes 81 Fish larva I (Fig.84)

82 Fish larva II (Fig.85)


Distribution and Abundance Monthly occurrence and distribution of zooplankton groups is

shown in Table 2. The collected zooplankton samples were dominated by copepods both in terms of species and numbers. Calanoid copepods represented by 38 species ranked first as the major component of the zooplankton, and followed by cyclopoid copepod (10 species) and harpacticoid copepod (6 species). Calanoid copepods: Paracalanus parvus, Acrocalanus similes, Pseudodiaptomus aurivilli, Metacalanus aurivilli, Labidocera pectinata, Acartia erythraea and A. spinicauda were dominated in almost all monthly collections with the maximum number of 521/m3, 410.5/m3, 421.05/m3, 210.52/m3, 531.6/m3, 142.1/m3 and 326.3/m3, respectively. With the highest numbers, the cyclopoid copepods: Oithona rigida (605.3/m3), O. brevicornis (568.4/m3), O. nana (147.4/m3), O. similes (1057.9/m3) and Corycaeus andrewsi (589.5/m3) were observed at almost all samples. Euterpina acutifrons was one of the major harpacticoid copepod which occurred in almost every month. The other copepod species were found in certain months of the year. Protozoa and Protochordata were common in almost all months. Other zooplankton groups: Coelenterata, Chaetognatha, Mollusca, Annelida, Echinodermata and Chordata were rarely found in the study area.

The estimation of zooplankton abundance in terms of cell density was based on direct counts of sample. Figure 2b shows the fluctuations of zooplankton abundance by month, referring to the number per m3. Overall the density values of zooplankton in all months were ranged from 1798 no/m3 (December) to 4000 no/m3 (October) (Table 3). The cell densities of zooplankton were found to be increasing trend from June to July, and then decreased in August. It then increased in September and October in line with the increase of salinity and decreased in November and December. In February, the density value was lower than that of January and March.


Fig. 3. Monthly variation in (a) Salinity and (b) temperature of study area. Table 2. Monthly occurrence and distribution of zooplankton taxa.

June

July

Aug

ust

Sept

embe

r

Oct

ober

Nov

embe

r

Dec

embe

r

Janu

ary

Febr

uary

Mar

ch

Protozoa 16 17 20 16 16 26 14 18 33 6

Coelenterata 0 0 0 0 0 0 0 0 2 3

Chaetognatha 0 0 0 11 11 7 0 15 0 3

Arthropoda 249 634 496 441 665 491 336 579 463 581

Mollusca 7 13 4 5 6 7 4 4 0 15

Protochordata larva 15 16 27 15 17 0 9 9 0 0

Fig. 2. Monthly variation in (a) number and (b) density of zooplankton species.


June

July

Aug

ust

Sept

embe

r

Oct

ober

Nov

embe

r

Dec

embe

r

Janu

ary

Febr

uary

Mar

ch

Annelida larva 0 0 0 0 0 0 0 0 11 17

Echinodermata larva 0 0 0 0 0 0 0 0 0 1

Chordata larva 0 0 0 0 0 0 0 0 0 1

Table 3. Monthly surface salinity, temperature and zooplankton abundance of study area.

Months Salinity (‰) Temperature ( °C) Abundance (no/m3)

June 23 27 1944.72

July 24 27 3532.66

August 24 27 2748.74

September 25 27 3834.17

October 27 27 4000

November 26 28 2723.62

December 26 28 1798.99

January 27 27 3361.81

February 26 29 2060.3

March 28 29 3271.36

Disscussion and Conclusion The occurrence and abundance of zooplankton is important

indication for the assessment on the abundance of fisheries resources. Some studies concerned with Myanmar plankton were carried out since 1969s. A total of 82 zooplankton species were recorded from the single study site. Although this occurrence of zooplankton species is decreased in compared with the previous study by Han Shein (1975), Kyi Win (1977) and Htay


Htay Mon (2009), the study waters is thus considered being rich in diversity of zooplankton populations as all monthly samples are composed of not less than 20 species of zooplankton. In all collections, copepods were predomoinant with 85.9% of total sample counts and followed by Protozoa (4.9%) and Protochordata (2.1%). This present observation of species composition was more or less similar to that of observation in Andaman Sea observed by Jitchum, Daungdee and Patrajinda (2006). Moreover, monthly dominant abundance of copepods in zooplankton populations in the present observation coincided with the various investigations of zooplankton in other regions described by Chew, Chong and Ooi (2008) and Htay Htay Mon (2009).

The abundance of zooplankton in terms of standing stocks ranged between 15.61 no/m3 and 478.61 no/m3 for 78 zooplankton taxa (Zin Lin Khine and Htay Aung, 2009) in Myanmar Territory waters of North-east Andaman Sea, 510 no/m3 - 109464 no/m3 for 119 taxa (Htay Htay Mon, 2009) in Setsè and Yathae Taung and 43.34 individual/m3- 185.17 individual/m3 for 65 groups of zooplankton taxa (Jitchum, Daungdee and Patrajinda (2006) in the Andaman Sea. According to the zooplankton species investigated in the Andaman Sea in 2006 including Indonesia, Myanmar and Thailand, the highest abundance of zooplankton species was observed in Myanmar waters. Total zooplankton abundance of the present study was in the range of 1798 no/m3 – 4000 no/m3 for 82 zooplankton species. Although there were different in species composition and abundance of zooplankton observed in different study areas, the investigations and results of zooplankton in various regions including present study show that copepods were the most dominant and abundance in zooplankton population.

The highest zooplankton abundance in this study occurred in the month of October and followed by September and January. During June and December, the zooplankton density declined to lowest level for a year. The affects of temperature and salinity on the seasonal distribution of different zooplankton groups have been indicated by Aung Kyi (1976) and Htay Htay Mon (2009). The present observation also showed that the increase of temperature and salinity coincided with the increase of zooplankton population, particularly copepod.

The mangrove environment is characterized by a large amount of organic materials and exposure to diurnal and seasonal variation of physico-


chemical conditions. Dead mangrove trees, fruits and leaves, together with decomposing dead under-ground fine roots provide organic detritus, primarily utilized by bacteria and fungi which convert undigestible plant tissue into a protein source for animals of the detritus food chain. Therefore, detritus, phytoplankton and zooplankton together in combination contribute the most biologically productive mangrove-estuarine ecosystem. It can be concluded that the study waters, mangrove tidal creek in Myeik Coastal Zone is highly productive and sustains a rich community of zooplankton in terms of species diversity and abundance, and thus it has been supporting various fisheries resources. Although the findings of this study based on 10 months period are inadequate to discuss the changes in structure of zooplankton community, still provide baseline data of zooplankton diversity common to Masan-pa mangrove waters. Further studies are needed to conduct the dynamics of zooplankton community in correlation with physical and chemical parameters of mangrove-lined estuarine waters in Myeik Coastal Zone.

8

4

10

5

9

6 7


Figures. 4-15. Zooplankton. Fig. 4. Tintinnopsis radix, Fig. 5. Favella taraikaensis, Fig. 6. Globigerina sp.1, Fig. 7. Muggiaea atlantica, Fig. 8. Globigerina sp.2, Fig. 9. Acanthometron sp., Fig. 10. Pyrocypris sp.1, Fig. 11. Diphyes sp. 1, Fig. 12. Sargitta enflata, Fig. 13. Canthocalanus pauper, Fig. 14. Nannocalanus minor, Fig. 15. Eucalanus subcrassus, (Scale bars, 0.5mm).

11 12

15

13

14


Figs. 16-32. Zooplankton. Fig. 16. Eucalanus attenuates. Fig. 17. E. monachus. Fig. 18. Paracalanus parvus. Fig. 19. E. crassus. Fig. 20. P. aculeatus. Fig. 21. P. crassirostris. Fig. 22. Acrocalanus gracilis. Fig. 23. A. gibber. Fig. 24. A. similes. Fig. 25. Euchaeta concinna. Fig. 26. Centropages furcatus. Fig. 27. C. tenuiremis. Fig. 28. C. dorsipinatus. Fig. 29. C. yamadai. Fig. 30. Pseudodiaptomus aurivilli. Fig. 31. P. hickmani. Fig. 32. Temora turbinate, (Scale bars, 0.3 mm).

15

17 18 19

20 21 22 23

24 25 26 27

28 29 30 31 32

16


Figs. 33-52. Zooplankton. Fig. 33. Metacalanus aurivilli. Fig. 34. Calanopia elliptica. Fig. 35. C. aurivilli. Fig. 36. C. thompsoni. Fig. 37. Labidocera acuta. Fig. 38. L. pectinata. Fig. 39. L. minuta,.Fig. 40. L. pavo. Fig. 41. L. kroyeri. Fig. 42. L. euchaeta. Fig. 43. Pontella danae. Fig. 44. Pontellopsis scotti. Fig. 45. Acartia erythraea. Fig. 46. A. negligens. Fig. 47. A. centrura. Fig. 48. A. spincauda. Fig. 49. A. danae. Fig. 50. Tortanus forcepatus. Fig. 51. Oithona spinirostris. Fig. 52. O. brevicornis. (Scale bars, 0.5mm).

33 34 36 37

38 39 40 41 42

43 44 45 46 47

48 49 50 51 52

35


Figs. 53-74. Zooplankton. Fig. 53. Oithona rigida. Fig. 54. O. simplex. Fig. 55. O. nana. Fig. 56. O. similis. Fig. 57. Oncaea venusta. Fig. 58. Kelleria regalis. Fig. 59. Corycaeus speciosus. Fig. 60. C. catus. Fig. 61. C. andrewsi. Fig. 62. Microstella norvegica. Fig. 63. M. rosea. Fig. 64. Clytemnestra rostrata. Fig. 65. C. scutellata. Fig. 66. Euterpina acutifrons. Fig. 67. Tigriopus sp 1. Fig. 68. Oikopleura cophocerca. Fig. 69. Tulbergella cuspidate. Fig. 70. Atlanta sp. Fig. 71. Lucifer penicillifer. Fig. 72. Trochophore larva I. Fig. 73. Trochophore larva II. Fig. 74. Pontellid nauplius.(Scale bars,0.3 mm).

74

530

54 55 56 57

58 59 60 61 62 63

64 65 66 67 68 69

70

71 72 73


Acknowledgements We would like to express our special thanks, to Dr Myint Shwe, Rector of Myeik University for his permission to carry out this research. We wish to acknowledge to Prof. U. Soe Htun, Head of Marine Science Department, Mawlamyine University, Prof. Daw Nang Mya Han, Head of Marine Science Department and all teachers from Myeik University, for their suggestions. The first author, Khin May Chit Maung, would like to thank her beloved parents, U Chit Maung and Daw May Lwin, for their physical, moral and financial supports throughout this study. In addition, funding for this work from the Department of Higher Education (Lower Myanmar), the Ministry of Education and the Department of Marine Science, Mawlamyine University is also mostly appreciated.

Figs. 75-85. Zooplankton. Fig. 75. Cirripede nauplius. Fig. 76. Cirriped cypris larva. Fig. 77. Brachyuran zoea I. Fig. 78. Brachyuran megalopa. Fig. 79. Brachyuran zoea II. Fig. 80. Bivalve larva. Fig. 81. Gastropod larva. Fig. 82. Ophiopluteus larva I. Fig. 83. Ophiopluteus larva II. Fig. 84. Fish larva I. Fig. 85. Fish larva II. (Scale bars, 0.2 mm)

75 76 77 78

790

80 81 82

83 84

85


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