Applied Science Reports www.pscipub.com/ASR E-ISSN: 2310-9440 / P-ISSN: 2311-0139 DOI: 10.15192/PSCP.ASR.2016.15.1.3134
App. Sci. Report. 15 (1), 2016: 31-34 © PSCI Publications
Zooplankton Species Composition and Abundance in the Brackish water axis of Sombreiro River, Niger Delta O.A.F. Wokoma Dept. of Biology, Ignatius Ajuru University of Education, P. M. B. 5047, Rumuolumeni, Port Harcourt. Corresponding author email:
[email protected] Paper Information
ABSTRACT An investigation into the zooplankton community with emphasis on Received: 19 December, 2015 species composition and abundance was carried out over a 2-year period in the lower (brackish water) reaches of the Sombreiro River. Triplicate Accepted: 28 March, 2016 samples were collected at each station using the filtration technique. 79 species of zooplankton belonging to four classes were encountered Published: 10 May, 2016 throughout the study, Rotifera had the highest number of species (26), followed by Protozoa with 20 species and Copeopda and Cladocera with Wokoma OAF. 2016. Zooplankton Species Composition 19 and 14 species respectively. Protozoa was the most dominant class in and Abundance in the Brackish water axis of Sombreiro terms of total abundance, accounting for 51% (31,040) of the total number River, Niger Delta. Applied Science Reports, 15 (1), 31-34. of zooplankton enumerated, followed respectively by Rotifera, Copepoda Retrieved from www.pscipub.com and Cladocera with 24% (14,440), 14% (8880) and 11% (6640). The most (DOI:10.15192/PSCP.ASR.2016.15.1.3134) encountered zooplankton species was the Protozoa Difflugia constricta with 6,520 individuals representing 21.50% of all the Protozoa encountered in the investigation. For class Rotifera, Parvocalanus crassirostris which accounted for 19.67% and followed closely by Mytilina ventralis and Epiphanies clavuletus accounting for 10.89% each were the most abundant Rotiferans. Four species of Copepoda Neudiaptomus incongruens, N. tubgkwariensis, Limnothemia sinensis and Acantia tosa were the most encountered Copepods, each accounting for 11.73% of the total number. Chydorus barroisi and Alonella exisa were the most common Cladocerans observed in this study. Variations in zooplankton diversity and abundance are contingent upon the place and time of sampling. © 2016 PSCI Publisher All rights reserved. Key words: Protozoa; Rotifera; Sombreiro River; Specie Composition; Total Abundance; Zooplankton Community
Introduction The quality and quantity of most aquatic organisms depends on the quality of their environment especially the physicchemical qualities and the characteristics of the water environment. These aquatic organisms include but not limited to extremely small floating organisms called plankton. Zooplanktons – planktons of animal origin utilize phytoplankton as food source and are in turn utilized by other invertebrates, shell fish and finfish (Emmanuel and Onyema, 2007). Zooplanktons occupy an important niche in the aquatic ecosystem as they constitute the most important link in energy transfer between phytoplankton and higher aquatic fauna (Iloba, 2002), and therefore are useful indicators of the future health of fisheries (Davies, et. al., 2009). Zooplanktons may be floating, drifting or even suspended in the water column and cannot therefore escape contamination by its own propulsion. This therefore, suggests that zooplanktons are good indicators of pollution in the environment. The term zooplankton is a broad categorization including organism’s small in size such as protozoans, and large metazoans. It also covers holoplankton and meroplanktonic organisms which spend part of their life cycle in the plankton phase before advancing to either the nekton phase or sessile benthic existence (Wikipedia Encyclopedia, 2010). Hart and Zabbey (2005) noted that in order to close the gap in knowledge of the living and non-living features, it is necessary to provide useful information on the zooplankton and their relationship with water physic-chemical properties of the creek. The biomass, abundance and species diversity of zooplankton can be used to determine the conditions of aquatic environment (MBO, 2007). Davies (2009) described zooplanktons as crucial components of the marine ecosystem where they play a major role in bio – monitoring of pollution. They are so integrated to the environment that they most often respond to changes more speedily than do other larger aquatic animals such as fish, and thus have proven to be a valuable indicator of apparent and subtle changes in the quality of aquatic environment (MBO, 2007).
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Materials and Methods Description of the study area The study area- Sombreiro River is located in Rivers State in the Niger Delta region of Nigeria, and lies between Latitude 60 301 to 70 01 E and Longitude 40 121 to 60 171N (Ezekiel et al.,2011a). It is a tidal dominated river, with possible fresh water input. The climate is classified as humid tropical of the semi hot equatorial type. The area experiences heavy rainfall from April to October with a mean rainfall estimated over 2000mm and mean annual temperature of about 29 OC. (UNEP, 2011). Recently heavy rains tend to begin by May, and even in the dry season months of November to March, sporadic heavy downpours are not uncommon. The vegetation of the river is predominantly mangrove with Rhizophora racemosa, Rhizophora mangle Gaertin and Rhizophora harosanii Leechman, as the dominant species (Abowei et al., 2008). In order to obtain samples for this investigation, ten (10) stations were established along the River. The stations as well as their location and global positioning system (GPS) coordinates are as in Table 1. Table 1: Sampling stations and their GPS Coordinates S/No 1 2 3 4 5 6 7 8 9 10
Station No. STN 1 STN 2 STN 3 STN 4 TNS 5 STN 6 STN 7 STN 8 STN 9 STN 10
Location Sikaka Kiri (Abandoned Fishing settlement) Bille Boko (Gateway to Bille) Minjudu-Kiri (Fishing settlement) Chevron Jokka Well Head 1 & 1D Idama Flow Station Idama Junction Da- obu Kiri (Fishing Settlement) Lele Kiri (Fishing Settlement) Erise Kiri (Fishing Settlement) Abonnema Urban
GPS Coordinates N 4˚ 34.692’ 4˚ 36.126’ 4˚ 36.423’ 4˚ 37.145’ 4˚ 37.703’ 4˚ 38.077’ 4˚ 39.353’ 4˚ 39.884’ 4˚ 40.796’ 4˚ 43.329’
E 6˚ 48.037’ 6˚ 50.418’ 6˚ 50.264’ 6˚ 49.556’ 6˚ 48.849’ 6˚ 48.498’ 6˚ 48.185’ 6˚ 46.630’ 6˚ 46.899’ 6˚ 46.476’
Field methods Prior to actual sampling, a reconnaissance survey of the stretch of River Sombreiro was carried out, during which, 10 sampling stations were established. Sampling stations were selected to capture all the “environmental action spots” on both sides along the coastline. An initial sampling was carried out during the reconnaissance visit, this is with the view to master field methods, get used to the sampling stations as well as equipment’s and above all eliminate likely sampling/ handling errors. Standard methods were adopted for sampling for all parameters and lasted for 24 months (from April, 2012 to March, 2014). Zooplankton samples were collected by Filtration technique. 25µm mesh size plankton net was towed from a boat for about a minute. The net content was washed out into a properly labeled wide mouth plastic container and preserved in 10% formalin solution. To each of the container was then added a few drops of eosin solution to make the organisms stained and visible during microscopic analysis in the laboratory. Samples were collected in three (3) replicates per station and transported to the laboratory in an ice- chest cooler. Laboratory Methods In the laboratory samples were allowed to stand for a minimum of 24 hours before decanting the supernatant. The supernatant was removed carefully until a 50ml concentrated sample was achieved. The concentrated sample was then properly shaken and 1ml sub-sample was collected from it and transferred into a Sedgewick Rafter counting chamber using a micro pipette. Identification and enumeration was carried out under a binocular compound microscope with magnification of 40 x 400. Three replicates of the sub-samples were analyzed. For each sample, each solitary cell was counted as one unit in a cell by cell basis. The result was then expressed in number of organisms per ml of sample. Identification and characterization of the planktonic species was based on the descriptive keys and illustrations of the following authors; Maosen, (1978) and Durand and Leveque (1980). Results And Discussion The Zooplankton community of Sombreiro River is composed of 79 species belonging to 61 genera and 4 classes see Table 2. Rotifera represented by 26 species (32.91%) were found to be the most prominent class, followed by Protozoa and Copepoda with 20 (i.e. 25.32%) and 19 (24.05%) species respectively and finally Cladocera with 14 species (17.72%). The genera occurring commonly are Lapadella and Parvocalanus for Rotifera Neodaptomus and Parocyclops for class Copepoda, Alonella and Daphnia for Cladocera and Diflugia for Protozoa.
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Table 2: Checklist Of Zooplankton Found In The Waters Of Sombreiro River S/NO 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26.
ROTIFERA Lepadella patella L. ovalis L. apsida Rotaria neptura R. rotatoria Mytilina ventralis Dicranophorus forcipatus D. caudatus Scandium longicaudum Asplanchina prioidonta Branchionus leydigi B. forficula Padalia mira Trichocerea rattus Parvocalanus crassirostris Lindia torulosa Mmostyla hamate Diurella weberi Pompholyx sulcata Synchaeta tremula Anuracopsis fissa Tigriopus californicus Ploesoma truncatum Testudinella patina Epiphanies clavuletus Cephalodella forficula
PROTOZOA Amoeba polypodia Tintinnopsis lacustris T.conicus Centropyxis aculeate C. constricta Phryganella sp. Didinium bolbianii Stentor polymorphus Vorticella mayerii Epistylis sp. Difflugia pyriformis D. constrita D. oblonga D. lobostoma Cyphodemia ampulla Pseudodileptus sp. Tintinnidium entzii Zoothannium arbuscula Marituja pelagica Euglypha tuberculata
COPEPODA Neudiaptomus incongruens N. pachypoditus N. tungkwariensis Canthocamptus staphylinus Acanthocyclops bicuspidatus Nitocra lacustris Limnoithona sinensis Mesochra suifunensis Schmackeria forbesi Heterocopa appendiculata Heliodiaptomus kikuchii H. serratus Boekella orientalis Parocyclops afinis Canthocamptus carinetus Eucyclops speratus Acantia tosa Sinediaptomus sarsi Limnocietodes bebeingi
CLADOCERA Simocephalus exspinosus S.vetulus Alonella rostrata A.exigna A.excisa Daphnia longis D.hyalina D. magna Dadaya macrops Sida crystalline Latonopsis australis Chydorus barroisi Ceriodaphnia setosa Bosmina fatalis
Zooplankton total class abundance observed in this investigation is shown in Fig. 1. In terms of class abundance, Protozoa dominated the Zooplankton community with 50.89% (31,040) of the total number of individuals enumerated. It was followed by the class Rotifera which had 23.67% (14,440) and then by Copepoda and Cladocera which had 14.56% (8880) and 10.89% (6640) respectively.
Cladocera 11%
Copepoda 14% Protozoa 51% Rotifera 24%
Figure 1. Zooplankton Total Class Abundance
In terms of species abundance, though there was no obvious dominance by any species, the most encountered zooplankton species was the Protozoa Difflugia constricta with 6,520 individuals representing 21.50% of all the Protozoa encountered in the investigation. For class Rotifera, Parvocalanus crassirostris which accounted for 19.67% and followed closely by Mytilina ventralis and Epiphanies clavuletus accounting for 10.89% each were the most abundant Rotiferans. Four species of Copepoda Neudiaptomus incongruens, N. tubgkwariensis, Limnothemia sinensis and Acantia tosa were the most 33
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encountered Copepods, each accounting for 11.73% of the total number. Chydorus barroisi and Alonella exisa were the most common Cladocerans observed in this study. The 79 species of zooplankton observed in this investigation is significantly higher than the 17 species belonging to 6 classes reported by Ezekiel, Ogamba and Abowei (2011b) in the fresh water axis of Sombreiro River, as the 24, 32 and 20 species recorded by Zabbey et. al., (2008), in Imo River; Davies et. al., (2009) in Elechi Creek, and Nkwoji et. al., (2010) respectively. It is however, comparable to the 67 species reported by Okogwu (2010) from Eboma Lake in the middle Cross River flood plain, the 63 species recorded by Josse de Paggi et. al., (2008) in a receiving pond of the storm water runoff from an urban catchment and the 71 species gotten by Vaidya and Yadav (2008) in the fresh water bodies of the Kathmandu valley. On the contrary, the investigation of Imumu (2011) revealed 93 species of zooplankton, which is slightly higher than the 79 species recorded in this study. The observed variation in the number of species from the different studies could be attributed to the differences in the natural conditions of the study environment and possibly the time of sampling. This explanation agrees with the observation of FAO (2006) that zooplankton distribution fluctuates from place to place and year to year due to the dynamic nature of the aquatic environment. It is also known that zooplankton migrates upward to the surface as darkness approaches and return to deeper areas at dawn, (Carney, 1990). The observation of four taxonomic classes of Rotifera, Protozoa, Cladocera and Copepoda (in their order of species dominance) is in consonance with the findings of Imumu (2011) and Ude et. al., (2011), but with a slightly different class dominance structure – Rotifera, Cladocera and Protozoa/Copepoda, and Cladocera, Rotifera/Copepoda and Protozoa respectively. Closely related to the observation of this study are the report of Vaidya and Yadev (2008) and Ezekiel et. al., (2011b) who recorded in the order of dominance Rotifera, Cladocera and Copepoda and Cladocera/Copepoda, Protozoa, Rotifera, and Decapod crustacean/ Euphasiacea respectively. The type and number of zooplankton class and species observed in any investigation is dependent upon the place and time of sampling. References Abowei JFN, Davies OA, Tawari CC. 2008. Phytoplankton in the lower Sombreiro River, Niger Delta, Nigeria. Research Journal of Biological Sciences 3(12): 1430 – 1436. APHA 2005. Standard Methods for Examination of water and waste water. American Public Health Association. Washington D.C. Carney H. 1990. A general hypothesis for the strength of food web interaction in relation to trophic state. Verh Internat. Verein Limnol., 24: 487 – 492. Davies OA, Tawari CC, Abowei JFN. 2009. Zooplankton of Elechi Creek, Niger Delta, Nigeria. Environ Ecol., 26(4c): 2441 – 2446. Durand JR, Leveque C. 1980. Flore et faune aquantiques de l’Afrique Cah. Off. Rech. Sci. Tech. Outre – Mer. 1: 5 – 46. Emmanuel BE, Onyema IC. 2007. The plankton and fishes of a tropical creek in South Western Nigeria. Turk.J. Fish. Aquat. Sc., 7: 105 – 113. Ezekiel EN, Ogamba EN, Abowei JFN. 2011a. Phytoplankton composition and abundance in Sombreiro River, Niger Delta, Nigeria. Curr. Res. J. Biol. Sci., 3(3): 229 – 233. Ezekiel EN, Ogamba EN, Abowei JFN. 2011b. The Zooplankton species composition and abundance in Sombreiro River, Niger Delta, Nigeria. Asian Journal of Agricultural Sciences, 3(3): 200 – 204. Food and Agriculture Organisation (FAO). 2006. Interrelationship between fish and plankton in inland water. http://fao.org/DOCRP 7580E03. Retrieved, Sept. 29, 2007. Hart AI, Zabbey N. 2005. Physic-chemistry and benthic fauna of Woji creek in the Lower Niger Delta, Nigeria. Environ. Ecol 23 (2): 361-368. Iloba KL. 2002. Vertical distribution of Rotifera in the Ikpoba Reservoir in Southern Nigeria. Trop. Freshwater Biol. 11: 69-89. Imumu SS. 2011. Plankton Community of Kugbo Creek. B. Ed. Project, Rivers State College of Education Port Harcourt, pp. 75. Jose de Paggi S, Paggi J, Collins P, Collins J, Graciela B. 2008. Water quality and Zooplankton composition in a receiving pond of the storm water runoff from an urban catchment. Journal of Environmental Biology. 29(5): 693 – 700. Maosen H. 1978. Illustration of Freshwater Plankton. Agricultural Press, Shanghai. MBO .2007. Marine Biology Organization life in the ocean-plankton, zooplankton retrieved Sept. 26, 2012. Nkwoji JA, Yakubu A, Ajani GF, Balogun KJ, Renner KO, Igbo JK, Ariyo AA, Bello BO. 2010. Seasonal Variations in water chemistry and benthic macro invertebrates of a South Western Lagoon, Lagos, Nigeria. J. Am. Sci., 6(3): 85 – 92. Okogwu IO. 2010. Seasonal variations of species composition and abundance of zooplankton eboma lake, a floodplain Lake in Nigeria. Rev. Biol. Trop., 58(1): 171 – 182. Ude EF, Ugwu LLC, Mgbenka BO. 2011. Evaluation of Zooplankton diversity in Echara River, Nigeria. Continental J. Biological Sciences 4 (1): 1- 5 UNEP. 2011. Environmental Assessment of Ogoniland. Nairobi: United Nations Environment Programme. Vaidya SR, Yadav UKR. 2008. Ecological study on zooplankton of some fresh water bodies of Kathmandu valley with reference to water quality. J. Nat. Hist. Mus. Vol. 23: 1- 11. Wikipedia Encyclopedia. 2010. Zooplankton. Retrieved September 26th, 2012. Zabbey N, Sikoki FD, Erondu J. 2008. Plankton assemblages and environmental gradients in the middle reaches of the Imo River, Niger Delta, Nigeria. Afr. J. Aquat. Sci. 33(2): 241 – 248.
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