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PRELIMINARY STUDY ON THE COMPOSITION AND ABUNDANCE OF SHELLFISH (DECAPODA: CRUSTACEA) IN UTA EWA ESTUARY, IKOT ABASI LOCAL GOVERNMENT AREA, ,

AKPAN, Akaninyene U doh , EGWALI, Edwin C huks , ESENOWO, Imeh K okoette and AKPABIO, Eno K in sley Department of Animal and Environmental Biology, University of Uyo , Akwa Ibom State , Nigeria.

Corresponding Author: Akpan, A. U. Department of Animal and Environmental Biology, University of Uyo , Akwa Ibom State , Nigeria . Email: [email protected] Phone: +234 8038981129

Received: September 23 , 2018 Revised: February 1 9, 2019 Accepted: February 27 , 2019

ABSTRACT

The study , Preliminary Study on the Composition and Abundance of Shellfish: Decapoda: Crustacea, in Uta Ewa Estuary was carried out between January and May 2012. The physico - chemical parameters of the water were measured in situ using standard methods according to APHA, AWWA and WEF (1998). Shellfish specimens were sampled monthly . Air - and water - temp erature ranged from 27.9 – 31.6 o c and 28.2 – 28.9 o c resp ectively, while DO , pH and salinity were between 3.28 – 4.09 mg/L, 6.40 – 7.7 ppm and 0.00 – 12.9 ppm respectively. The mean values of the physico - chemical parameters measured were not significant a t r = 0.456. Pandalus sp . was the most abundant in station 1 accounting for 50.29 %, followed by Nematopalaemon hastatus which accounted for 29.21 % , while in station 2, N . hastatus was the most abundant, accounting for 39.78 %, followed by Pandalus sp . a ccounting for 31.40 % of the relative abundance. Panopeus africanus was the least collected shellfish species, it accounted for 0.14 % in station 1 and 0.45 % for station 2. Station 2 had shellfish Shannon diversity of 1.54 while station 1 had 1.31. The ph ysico - chemical parameters show ed significant relationship with the abundance of the shellfish species (p<0.05). The results of air - and water - temperature and pH were within limits of stipulated minimum values of the National Environmental Standards and Reg ulations Enforcement Agencies (NESREA) for aquatic life. Uta Ewa estuary is rich with a wide variety of shellfish species of ecological and economical importance; hence the coastal area should be monitored and protected from pollution.

Keywords : Shellfis h, Decapoda , Uta Ewa estuary, Composition , Abundance

INTRODUCTION both direct and indirect employment (Okayi et al. , 2013 ). Shellfishes of the Decapoda: Crustacea are of Decapod shellfish comprise crabs, great commercial importance in Nigeria prawns and shrimps. Thus several shellfish territorial waters and the exploitation has been species from the three groups : crabs on the increase due to demand for protein ( Cardiosoma armatum, Callinectes amnicola, sources f or human consumption as well as Goniopsis pelii and Ocypode afric ana ) , prawns source of income for coastal towns and villages ( Macrobrachium sp . , Nematopalaemon hastatus ) of the Nigeria Delta environment (Bankole, and shrimps ( Parapanaeopsis sp . and Pandalus 2007; Adebayo - Tayo and Ogunjobi , 2008; Okayi sp . ) , have been reported in coastal brackish et al., 2013). Nigeria’s shrimp fisheries, both water bodies of Nigeria ( Marioghae , 1982 ; industrial and artisanal, are a major so urce of Powell, 1982 ; Shaw et al., 1988; Enin, 1998 ; Chin dah et al., 2000 ; Lawal - Are and Kusemiju,

ISSN: 1597 – 3115 ARI 2019 16(1): 3198 – 3206 www.zoo - unn.org Akpan et al. 3199

2000 ; Okayi et al., 2013 ; Olawusi - Peters and include trading on fish es ( both fresh and Ajibare, 2014 ; Onadeko et al., 2015 among smoked ) , f uel wood cutting and water many others ) . transportation are also carried out (Esenowo et Uta Ewa estuary is known for its high al., 2016). Two sampling st ations with unique productivity and rich biodiversi ty, including a ecological characteristics and human activities wide variety of finfish and shellfish spe cies were established along the length of the (Akpan, 2013; Akpan and Etim, 2015; Esenowo e stuar y . The sampling stations were about two et al. , 2016 ) . This research was directed to the kilometr e s apart from each other. preliminary study of the shellfish species composition and abundance in the coastal area Station 1 : Is located upstream of the Uta Ewa and to complement existing information on estuary with human settleme nt and local market Decapoda of Uta Ewa estuary and other on the left flank of the shoreline. Vegetation is estuaries i n Nigeria . sparse with mainly mangrove Rhizophora sp . and N i pa palm ( Nypa fruticans ) . The station is MATERIALS AND METHODS v ery shallow and the bottom when expose d at low t ide is made of fine sand. Human activities Study Area : Uta Ewa estuary is located within included logging of the mangrove, sand Latitude 4 o 32’ to 4 o 52’N and Longitude 7 o 25’ to dredging, washing of boats, cano e s and fishing 7 o 45’E ( Fig ure 1 ). ne ts and swimming.

Station 2 : Is about two kilometers away from s tation 1, downstream of the estuary with no human settlement . On the shorelines are thick vegetation of mangrove Rhizophora sp . and N i pa palm. The station is deep and at low tide, the greater part of the bottom mud fla t is exposed. Human activities in this station are minimal, with mainly fishing activity on the high .

Physico - Chemical Parameters : The following physical and chemical parameters were determined: air temperature, water temperature, pH, dissolved oxygen (DO), depth, transparency and salinity. Air and water temperature, transparency, salinity and depth were determined in situ , Dissolved oxygen was determined in the laboratory. Surface water samples were collected in 2 litre glass bottles Figure 1: Map of the study area showing Uta containers after they were rinsed with distilled Ewa Beach and the sampling stations water fro m each sampling stations. T he estuary lies on the western bank of Enong Air and water temperature s were taken creek about 12 km from the mouth of Imo using a centigrade mercury - in - glass River . Characteristically, the area is typical of an thermometer. Air temperature was measured by estuarine tidal water zone with freshwater input holding the thermometer in the air for 3 from Imo River and with extensive mangrove minutes. Water temperature was measured by swamps and intertidal mud flats. The estuary is inserting the thermometer t o a depth of 10 cm bounded by thick mangrove forest dominated into water for 3 minutes. Reading was taken by Rhizophora species and interspersed by N i pa three times and mean value recorded. The palm ( Nypa fruticans ) . The main occupation of results were expressed as degree Celsius (°C). the people is fishing , while o ther activities

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Water sample from each station was carefully The shellfish specimens collected were collected into 250 mL stoppered samplings preserved in an iced packed chest box in the bottle without air bubbles and immediately 1 ml field (Lawal - Are, 2009) and la ter transferred to

MnSO 4 solution was added, followed by 1 ml the Entomolog y Laboratory of the Department alkali - iodide - azide reagent, and 2 ml Conc. of Zoology , University of Uyo, for sorting and

H 2 SO 4 . In the laboratory, the DO concentration identification according to identification keys of the treated water sample was determined as provided in FAO (1981) . reported by APHA, AWWA, WEF ( 1998 ) . The result was expressed as mg/L. An Extech meter Data Analysis : Micr osoft Excel 2007 was used ( Model ExStik EC400 ) was used to measure for data analysis for the pe rcentage abundance salinity. The meter was calibrated with 3.3 mol of the shellfish , mean and standard error of the solution of potassium chloride. The glass physicoc hemical parameters of the study electrode of the meter was inserted into the stations , while ve rsion 3 of PAST Software water sample after being rinsed with dis tilled Design was used to determ ine the shellfish water and measurement was taken after the species diversity ( Shannon Diversity i ndex ) and reading had stabilized. The result for salinity richness ( Marg alef ) of the shellfish community was expressed as part per thousand (‰). composition in each sample station s . SPSS The pH was measured using electronic version 20.0 was used for correlation analysis pH meter (Oakton waterproof Instruments pH on the relationship between th e physiochemical tester 10). The pH meter was standardiz ed parameters and shellfish abundance. using prepared buffer solution according to the manufacturer's instruction. Water sample was RESULTS put into a beaker after it was rinsed with distilled water. The glass electrode of the meter Physico - Chemical Parameters : The results was inserted into the water sample and on range, mean and standard error of the measurement was taken after the reading had physico - chemical parameters measured are stabilized. presented in Table 1 . The lowest mean value for For depth an improvised long pole was salinity of 2.98 ppt was recorded for Station 2, dipped into the river; the pole was marked and while the highest mean value for salinity (10.14 later measured out with a measuring tape. The ppt) was recorded for Stati on 1. The mean result was expressed in metre. Transparency values for the physico - chemical parameters was measured using a Secchi disc measuring measured were not significant in Stations 1 and about 20 c m in diameter. The Secchi disc was 2 at r = 0.456 (p ≤0.05). lowered into the water and the suspended rope that was marked was later measured out. The Shellfish Composition and Abundance: The result was expressed in metre. composition and abundance of the shellfish species encountered from the sampling s tations Shellfish Sampl ing : The crab , prawn and in the study area are presented in Table 2 . A shrimp species were collected on monthly basis total of 1583 individuals of the shellfish species between the months of January and May 2012. were sampled in the sampling stations, with 688 Crabs species were collected using square lift sampled in S tation 1 and 895 sampled in S tation net at low tide. The prawns and shrimps were 2. The shellfish species comprised eight families . collected with the assistance of artisanal Five Families : Grapsidae, Gecarcinidae, fishermen. The artisanal fishermen used boats Ocypodidae, Portunidae and Xanthidae made up with sizes ranging from 5 to 12 m in length . The the crabs, while one Family : Palaemonidae boats were powered by small outboard engines made up the prawn s and two Families ; and manned by an average of two men per Penaeidae and Pandalidae made up the boat, to which the harvesting nets were shrimps. attached.

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Table 1: The range and mean of the physico - chem ical parameters of the water sample from the Uta Ewa Estuary , Akwa Ibom State, Nigeria Parameter Station 1 Station 2 Range Mean Range Mean Air temperature ( o C) 27.9 - 31.6 29.86 ± 1.55 28.6 - 30.3 29.56 ± 0.69 Water temperature ( o C) 28.2 - 28.9 28. 40 ± 0.29 28.1 - 28.9 28.36 ± 0.36 Dissolved Oxygen DO (mg/L) 3.28 - 4.09 3.71 ± 0.40 3.55 - 3.79 3.68 ± 0.10 Salinity (ppt) 7.5 - 12.9 10.14 ± 2.53 0.00 - 4.3 2.98 ± 2.05 pH 7.3 - 7.7 7.44 ± 0.19 6.40 - 7.0 6.74 ± 0.24 Depth (m) 2.5 - 11 5.48 ± 3.30 1.50 - 4.0 3.24 ± 1.12 Transparency (m) 0.45 - 0.83 0.66 ± 0.19 1.10 - 1.65 1.50 ± 0.23

Table 2: The composition and abundance of the shellfish encountered in sampl ed stations of Uta Ewa Estuary, Akwa Ibom State, Nigeria Family S hellfish species Common Station 1 Station 2 name name Ni % Ni % Grapsidae Goniopsis pelii Purple 13 1.89 40 4.47 (Herklots, 1851) mangrove crab Gecarcinidae Cardisoma armatum Land crab - - 5 0.56 Crabs (Herklots, 1851) Ocypodidae Ocypo de africana de Ghost crab 2 0.29 10 1.12 Man, 1881 Portunidae Callinectes amnicola Swimming 34 4.94 41 4.58 (Rochebrune, 1883) crab Xanthidae Panopeus africanus A. 1 0.14 4 0.45 Milne - Edwards, 1867 50 100 Nematopalaemon Estuarine 201 29.21 356 39.78 Prawn Palaemonidae h astatus (Aurivillius, prawn 1898) Macrobrachium Brackish river 39 5.67 83 9.27 macrobrachion prawn Herklots, 1851 240 439 Penaeidae Parapenaeopsis sp Guinea shrimp 52 7.56 75 8.40 Shrimp Balss, 1914 Pandalidae Pa ndalus sp Shrimp 346 50.29 281 31.40 398 356 Grand Total 688 895 n i = number of individual shell fish species; % = percentage % ) and crab species C . amnicola ( 4.58 % ) . Crab From the overall resul ts on composition and species , Panopeus africanus (Figure 5) , with abundance , shrimp species, Pandalus sp . percentages of 0.14 and 0.45 , were the least (Figure 2) ( 50.29 % ) accounted for the most encountered shellfish species in S tation 1 and 2 , abundan t shellfish species in S tation 1, followed respectively. The results o f the shellfish species by prawn species , N. hastatus (Figure 3) ( 29.21 diversity ( Shannon ) and richness (Margale f) are % ) and crab species C . amnicola (Figure 4) with presented in T able 3 . A relatively high species 4.94 %. In S tation 2, prawn species , N. diversity (1.54) and richness (1.18) w ere hastatus ( 39.78 % ) was the most abundan t , recorded for S tation 2, while relatively low followed by sh rimp species , Pandalus sp . ( 31.40 species diversity (1.31) and richness (1.07) w ere recor ded for S tation 1.

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Figure 5 : Panopeus africanus from Uta Ewa

Estuary, Akwa Ibom State, Nigeria , Mag. 0.15 Figure 2: Pandalus sp . from Uta Ewa Estuary, m Akwa Ibom State, Nigeria , Mag. 0.1 2 m

Table 3: Ecological indices of the shellfish from Uta Ewa Estuary, Akwa Ibom State, Nigeria Ecological Indices Station Station Total 1 2 Diversity indices 688 895 1583 Shellfish species 1.31 1.54 diversity (Shannon) Shellfish species 1.07 1.18 richness (Margalef)

Figure 3 : Nematopalaemon hastatus from Uta From the result , water temperature had positive Ewa Estuary, Akwa Ibom State, Nigeria , Mag. correlation relationship with Parapenaeopsis sp. 0. 11 m and was significant ( r = 0.91; p<0.05 ) ( Table 4 ), an d negatively correlated with O. africana ( r = - 0.91; p<0.05 ) and Pandalus sp. (r = 0.96, p<0.05) in station 2 ( Table 5 ). Dissolved oxygen positively correlated with G. pelli ( r = 0.96, p<0.05 ) , N. hastatus ( r = 0.93, p< 0.05 ) and Pandalus sp. ( r = 0.97, p< 0.01 ) in station 1 ( Table 4 ). In station 2, DO positively correlated with N. hastatus ( r = 0.98 and p<0.05 ) and negatively correlated with C. amnicola (r = -

0.97 and p<0.05) . pH had significant positive Figure 4 : Callinectes amnicola from Uta Ewa Estuar y, Akwa Ibom State, Nigeria , Mag. 0.17 correlation relationships with C. amnicola ( r = m 0.97 , p<0.01 ). Transparency did not show significant correlation (p>0.05) with the shellfish Relationship between Physicochemical species abundance ( Table 4) . Parameters and Shellfish Abundance: The results on relationship between physicochemical DISCUSSION parameters and shellfish abundance in station s 1 and 2 are presented in Tables 4 and 5. Physico - Chemical Parameters: According to Costa and Fransozo (2004), the important factors that affect composition and abu ndance of shellfish species in the tropical region are water quality.

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Table 4: Relationship between physico - chemical parameters and shellfish abundance in station 1 of Uta Ewa Estuary, Akwa Ibom State, Nigeria Physico - chemical Goniopsis Ocypode Callinectes Panopeus Nematopalaemon M acrobrachium Parapenaeopsis Pandalus parameters pelii africana amnicola africanus hastatus macrobrachion sp. S p . Air temperature - 0.69 - 0.98** 0.51 - 0.75 - 0.55 - 0.32 0.99** 0.98* Water temperature - 0.40 - 0.65 0.78 - 0.99** - 0.80 0.03 0.91* 0.96* Dissolved oxygen 0.96* 0.61 0.53 0.20 0.93* - 0.49 - 0.52 0.97** Salinity 0.53 - 0.08 0.96* - 0.50 0.95* 0.89* 0.18 0.91* pH 0.43 - 0.19 0.97** - 0.91* 0.98** 0.65 0.29 0.98** Depth 0.40 - 0.32 0.89* - 0.59 - 0.72 0.76 0.62 0.42 Transpar ency 0.36 - 0.17 0.45 - 0.42 - 0.32 0.70 0.13 0.40 * Correlation is significant at the 0.05 level (2 - tailed); ** Correlation is significant at the 0.01 level (2 - tailed)

Table 5 : Relationship between physico - chemical parameters and shellfish abundance in sta tion 2 of Uta Ewa Estuary, Akwa Ibom State, Nigeria Physico - chemical Goniopsis Cardiosoma Ocypode Callinectes Panopeus Nematopalaemon Macrobrachium Parapenaeopsis Pandalus parameters pelii armatum africana amnicola africanus hastatus macrobrachion sp. Sp. Air temperature - 0.97* - 0.69 - 0.94* - 0.66 - 0.37 0.70 0.45 0.28 0.46 Water temperature - 0.61 - 0.74 - 0.91* - 0.59 - 0.44 0.75 0.51 0.21 0.52 Dissolved oxygen - 0.72 0.32 - 0.79 - 0.97* 0.70 0.98* - 0.63 0.99 ** 0.94* Salinity 0.29 0.99 ** 0.19 - 0.21 0.56 - 0.99 ** - 0.98* 0.55 - 0.98* pH 0.086 0.94* - 0.02 - 0.42 - 0.99 ** - 0.93* - 0.99 0.71 - 0.99 ** Depth 0.97* 0.20 0.99 ** 0.96* - 0.25 - 0.21 0.16 - 0.80 0.15 Transparency - 0.22 0.79 - 0.31 - 0.67 0.98* - 0.78 - 0.96* 0.89 - 0.95* * Correlation is significant at the 0.05 level (2 - tailed); ** Correlation is significa nt at the 0.01 level (2 - tailed)

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The physicochemical parameters of any water Pandalus sp . was the most abundan t body are vital ecological factors, as they directly shellfish species encounte red in S tation 1. The affect oxygen consumption, metabolism, station is characterized with few mangrove growth, moulting, hormones and survival of ( Rhizphora species ), N ypa palms and fine sandy crus taceans (Chen et al., 1995; Medesani et al ., bottom . These features may have been 2001; Onadeko et al., 2015). The dissolved interplaying factor s favou ring the population of oxygen (DO) values of 3.71 mg/L and 3.68 the shellfish species abundance (Es enowo et al., mg/L for Station 1 and Station 2 respectively, 2016 ) . In S tatio n 2, N . hastatus was the most were slightly low compared to the National abundan t . The features such as thick vegetation Environment Standards and Regulations of mangrove ( Rhizophora sp . ), N i pa palm on the Enforcement Agency (NESREA) limits of shorelines and muddy bottom may have minimum value of 6.0 mg/L for surface water favoured the population and survival of the fisheries. According to Esenowo et al. (2017), species in the station (Onadeko et al., 2015; this indicates that Uta Ewa brackish water Esen et al., 2016) . The results on the estuary is a less oxidized aquatic ecosystem. composition and abundance of shellfish in Uta However, pH and transparency were with in Ewa estuary was contrary to the results from recommended limits as stipulated by NESREA Marioghae (1982) in the Lagoon , Powell for aquatic life. Although salinity was low in (1982) in the Niger Delta , Enin (1998) in the Station 2, this could be attributed to the Cross River estuary and Olawusi - Pete rs and intrusion of freshwater into the brackish water Ajibare (2014) in the coastal waters of Ondo during low tide (Esenowo et al., 2016) . State , who reported Macrobrachium macrobrachion a s the most dominant shellfish Shellfish Composition and Abun dance : The species. results on the composition and abundance of Comparatively, S tation 2 has high er the shellfish in the study area are indication that abundan ce of shellfish species than S tation 1. the water body is rich with diverse shellfish The relatively low composition a nd diversity of species. G . pelii, C . armatum, O . africana, C . shellfish species in S tation 1 may be as a result amnicola and Panopeus africanus (Esenowo et of pressure from anthropogenic activities as well al., 2016) m ade up the crab grou p of the as physico - chemical parameters ’ instability. shellfish composition, while the prawn group According to Kennish (2002), anthrop ogenic was made up of N. hastatus and Macrobrachium activities could lead to the periodic or macrobranchion , and shrimp group include permanent e limination of estuarine dependent Parapanaeopsis sp . and Pandalus sp . All the shell fish species from the estuary . Nevertheless, shellfish species were caught in both S tation s 1 the shellfish species encountered strive well in and 2 except C . armatum that was not caught in amphibious areas (Onadeko et al., 2015) , a S tation 1. Also, of these species reported in this characteristic feature of S tation 2. However, the research, N. hastatus, M. macrobrachio n , results on the diversity indic es of the shellfish Parapanaeopsis, O. africana, and C. amnicola species in the study area indicated that there have been reported by Ofor (2002), Zabbey was relatively high er shellfish species diversity (2007), Olawusi - Peters and Ajibar e (2014) in in S tation 2 than in S tation 1. Also, shellfish other estuaries in Nigeria and are major catches species richness was relatively higher in S tation for artisanal fishermen. According to Shaw et 2 than S tation 1 (Esenowo et al., 2016) . al. (1988) the shellfish species are accepted as food organisms and support a substantial Relationship between Physicochemical number of local fisheri es. Besides, the prawn , N . Parameters and Shellfish Abundance : The hastatus , is the major constituent and an correlation relationship between physico - essential food condiment in almost all local chemical parameters and the shellfish species dishes of the area, in cluding the South East , abundan t results indicate that physico - chemical South - South and further north in Nigeria (Okayi parameters such as depth and transparency et al., 2013). were not major determining parameters for the

Animal Research International (2019) 16(1): 3198 – 3206 Akpan et al. 3199320 5 abundan t of the shellfish species in station 1 Oceanography and Marine Ecological and station 2, but air - and water - temperature, System, 4: 31 – 35 . dissolved oxygen, salinity and pH were . The APHA, AWWA and WEF (1998). Standard abundan t of Pandalus sp . in station 1 and N. Methods for the Examination of Water hastatus in station 2 is p ositively correlated to and Wastewater . 20 th Ed itio n, American dissolved oxygen. The negative correlation Public Health Association, American result of dissolved oxygen with C. amnicola in Water Works Association and Water station 2 show competition for oxygen demand Environmental Federation , Washington among the shellfish species. The demand for DC, United States. oxygen among the shellfish species may be BANKOLE , M. Y. (2 007). Some Aspects of t he caused by h igh metabolic activities (Eyo and Reproductive Biology of Freshwater Ekwonye , 1995 ). Prawn ( Macrobrachium vollenhovenii ) and Brackish Water Prawn Conclusion : It could be concluded that Uta ( Macrobrachium macrobrachion ) . Ewa estuary is rich with wide variety of shellfish M. Tech Thesis, The Federal University species of Decapoda (Crustacea) . However, of Technology , , Nigeria . given the ecological and economical values of CHEN, S., WU, J., HUNER, J. V. and MALONE, R. the shellfish speci es reported in this study, there F. (1995). Effects of temperature upon is need for the monitoring and control of ablation - to - molt interval and mortality pollution in the coastal area for sustainability of of red swamp crawfish ( Procambarus th is aquatic biodiversity. clarkii ) subjected to bilateral eyestalk ablation. Aquaculture , 138 (1 - 4): 191 – ACKNOWLEDGMENTS 204. CHINDAH, A. C., TAWARI, C. C. B. and Our sincere gratitude goes to the artisanal IFECHUKW UDE, K. A . (2000). The food fishermen who assisted in the collection of the and feeding habits of the swimming shellfishes. crab, Callinectes amnicola (Portunidae) of the new River, Nigeria. REFERENCE S J ournal of Applied Sci ence and Environ mental Manage ment, 4: 051 – ADEBAYO - TAYO, B. C. and OGUNJOBI, A. A. 057 . (2008). Comparative effects of oven COSTA , R. C. and FRANSOZO , A. (2004). dried and sun - dried on the Abundance and ecologic distribution of microbiological, proximate nutrient and the shrimp Rima penacus constrictus mineral composition of Trypanotous (Crustacea: Penaeidae) in the northern spp. (Periwinkle) and Crassostrea spp . coast of Sao Paulo, Brazil. J ournal of (Oys ter). Electronic J ournal of Nat ural History , 38(7): 901 – 912 . Environment, Agric ulture and Food ENIN , U. I. (1998). The Macrobrachium fishery Chem istry, 7 (4): 2856 – 2867 . of the Cross River estuary, Nig eria. AKPAN, I. I. (2013). Species composition and Archive of Fishery and Marine abundance in Uta Ewa creek , Niger Research , 46 ( 3): 263 – 272 . Delta Region, Nigeria. IOSR Journal of ESENOWO, I. K., AKPAN, A. U., EGWALI, E. C. Agriculture and Veterinary Science , and AKPABIO, E. E. (2016). The 3 (3): 56 – 60. abundance and composition of crabs AKPAN, I. I. and Etim, U. (2015). Observations (Decapoda) in Uta Ewa brackish water, on the variations (seasonal and spatial) Akwa Ibom State, South - South, in water quality and ecological adversity Nigeria. Jou rnal of Applied Sciences and of Uta Ewa, Niger Delta region , Environmental Management , 20 (4): 919 Nigeria. International Journal of – 924.

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ESENOWO, I. K., UGWUMBA, A. A. A. and OFOR, C. O. (2002). Exploitation rate and by - AKPAN, A. U. (2017). Evaluating the catch of Ne matopalaemon hastatus physico - chemical characteristics and (Crustacean: Palaemonidae) ( Arivillius, plankton diversity of Nwaniba River, 1898) fishery in the Cross River estuary , South - South Nigeria . Asian Journal of Nigeria. J ournal of Aqua tic Sci ence , Environment and Ecology , 5(3): 1 – 8 . 17(1): 13 – 16. EYO, J. E. and EKWONYE , U. C. (1995). The OKAYI, R. G., SOLOMON, S. G., ATAGUBA, A. macroinvertebrate fauna of pool in the G., CHUKWUDI, O. P. and MBATA, F. U. flood plan (Fadama) of the Anambra ( 2013). Indigenous k nowledge of River, Nigeria. Freshwater Forum, 5(3): shrimps and prawn species and fishing 160 – 162 . of the Benue and Niger River (middle – FAO (1981). FAO Species Identification Sheets belt savannah) – Nigeria. Agriculture f or Fishery Purposes: Western Central and Biology Journal of North America , Atlantic (Fishing Area 31). Food and 4(3) : 221 – 226 . Agriculture Organization of the United OLAWUSI - PETERS, O. O. and AJIBARE, A. O. Nations, Geneva, Switzerland. (2014). Species abundance and KENNISH, M. J. (2002). Environmental threats di stribution patterns of some shellfishes and environmental future of in coastal waters of Ondo State, estuaries. Environmental Southwest of Nigeria. International Conservation , 2 9 (1): 78 – 107. Journal of Fauna and Biological LAWAL - ARE, A. O. and KUSEMIJU, K. (2000). Studies , 1 (4): 19 – 24. Size composition, growth pattern and ONADEKO, A. B., LAWAL - ARE, A. O. and feeding habits of the blue crab IGBORGBOR, O. S. (2015). Habitat Callinectes amnicola (De Rocheborne) in diversity and species richness of the Badagry Lagoon, Nigeria Journal of brachyuran crabs off University of Lagos Science Research and Development , 4: Lagoon Coast, Akoka, Nigeria. The 117 – 126. Bioscientist , 3 (1): 14 – 28. L AWAL - ARE , A. O. (2009). Food and feeding POWELL , C. B. (1982). Freshwater and brackish habits of the blue crabs , Callinectes water shrimps of economic importance amnicola (de Rocheburne) from three in the Niger Delta. Pages 254 – 285. In : different interconnecting lagoons in Proceedings of 2nd Annual conference south - west , Nigeria. European J ournal of the Fisheries Society of Nigeria, of Sci entific Research, 32(1): 088 – 094. Calabar , Nigeria. MARIOGHAE , I. E. (1982). Notes on the biology SHAW, W. N., HASSLER, T. J. and MORAN, D. P. and distribution of Macrobrachium (1988). Species Profiles : Life Histories vollenhovenii and Macrobrachium and Environmental Requirements of macrobrachion in the Lagos Lagoon Coastal Fishes and Invertebrates (Crustacea, Decapoda, Palaemonidae). (Pacific Southwest) Calif ornia Sea Revue Zoologique Africaine , 96 (3): 493 Mussel and Bay Mussel . Fish and – 508 . Wildlife Service, Washington DC, USA. MEDESANI, D. A., GRECO, L. L. and ZABBEY, N. (2007). Small Scale Shrimp RODRÍGUEZ, E. M. (2001). Effects of Fisheries in Nigeria . Technical Report, cadmium and copper on hormonal CEHRD/TESH/CONSERV/01/: 64 , Centre regulation of glycemia by the eyestalks for Environment, Human Rights and in the crab Chasmagnathus granulata . Development, Eleme, Rivers St ate , Bulletin of Environmental Contamination Nigeria . and Toxicology , 66 (1): 71 – 76.

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