Polychaete feeding Guild

AARJMD VOLUME 1 ISSUE 18 (FEBRUARY 2014) ISSN : 2319 - 2801

Asian Academic Research Journal of Multidisciplinary

www.asianacademicresearch.org

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A Peer Reviewed International Journal of Asian

Academic Research Associates

AARJMD

ASIAN ACADEMIC RESEARCH

JOURNAL OF MULTIDISCIPLINARY

TEMPORAL VARIABILITY IN FEEDING GUILDS OF

POLYCHAETE FAUNA AT THE

MOUTH OF THE BONNY ESTUARY, NIGERIA.

JOHN ONWUTEAKA*

* Department of Applied and Environmental Biology

Rivers State University of Science and

TechnologyPort Harcourt, Nigeria

Abstract

Temporal variations in feeding guilds of Polychaetes were studied at the mouth on Bonny

River bar in the eastern delta of the Niger delta in Nigeria. The trophic group composition

identified the existence of five (5) groups namely Carnivores (C), Surface Deposit Feeders

(SDF), Subsurface Deposit Feeders (SSDF); Herbivores (HBVR) and Suspension Feeders

(SF). The study showed evidence of monthly variability within-feeding guilds. However no

pattern of seasonal variation was evident as there was no significant difference between the

wet season months of June 2010, August2010 and October 2010 and the dry season months

of February 2011 and April 2011. However within –group variation showed a consistent

pattern of significant difference between the carnivore feeding group and the other four

feeding guilds in June 2010 and 2011(SSDF, SDF, HBVR, SF) , three feeding groups in

February and April 2011(SDF, HBVR, SF) ; two feeding groups in October 2010(HBVR,

SF) and one feeding group in August 2010 (SF). The consistently dominance of the

carnivore group throughout the survey period is linked to the likely presence of coarse

sediments created by the regular maintenance dredging activity at the river mouth to enable

large vessels load oil and gas products.

Keywords: Temporal Variation, Polychaete feeding Guilds, Bonny River

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1.0 Introduction

The Bonny estuary is recognized as one of the most important river system in the eastern

delta providing transportation for oil and gas services into the inland Ports at Onne and

Okirika and Port Harcourt for commerce. The estuary which supports large scale maritime

activity also support a diverse ecology and rich fisheries and has been the focus of many

multidisciplinary research (RPI 1985, IPS 1989, 1990 and 1992). In these studies, NNPC/RPI

(1985) extensively provided information on the physicochemistry and Plankton,Ombu

(1987), and Ekweozor et al. (1989) on benthos and Hart and Chindah (1998) on intertidal

macrofauna while Chindah and Osuamkpe (1994), on fisheries of Bonny estuary. While these

studies provide information of environmental response to changes that may result from

pollution, many other environmental stresses such as dredging exist and studies that focus on

trophic levels are needed to complement the efforts of past research. In order to complement

past research efforts, the present study conducted a survey of the temporal variation in the

feeding groups of subtidal Polychaetes within the Polyhaline environment at the mouth of

Bonny River where salinity values remain stable without variation (NEDECO 1961,

NNPC/RPI 1985). As a result this study intends to evaluate the temporal variation in

composition of feeding groups of Polychaetes in the absence of a seasonal salinity gradient.

2.0 Study Area

The study area is located within the mouth of the Bonny River Estuary as shown in Fig 1.0.

Bonny River Estuary has been described with a tidal penetration extending inland over 40

kilometers. The extended salinity propagation of the Bonny tidal basin is due to the

morphology which induces a high tidal conductivity (NEDECO 1963). These studies show

that the mouth of the river remain at salinities of 20 ppt throughout the year through the wet

and dry season because of the ineffectual influence of fresh water discharge.

3.0 Field Procedures

Samples at the river mouth were collected in three locations, upper, mid and lower areas as

shown in Fig 1.0.The stations were chosen around buoys on the river to make it easier to

anchor the boat within the strong current. At each location five random sites were sampled by

collecting with a 0.023m2 Ekman grab. All samples from the sites at each location were




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composited. The three locations were sampled every two months through a 12 month period

by using waypoints loaded into a GPS to collect samples from the same location as closely as

possible. The grab samples were washed with water in a 45µ nitex bags, and preserved in

10% buffered formalin. Rose Bengal stain was added. Each preserved samples were hand

sorted. All polychaetes were sorted, identified with stereo and compound microscope and

categorized into families and generic groups. Polychaete texts used were Day (1967) and

Fauchald (1977). The trophic group classification applied for each family was simplified from

the scheme proposed by Fauchald and Jumars (1979) with individuals being assigned to

broad feeding categories—predators (carnivores plus omnivores), surface deposit feeders,

burrowing subsurface deposit feeders (hereafter termed burrowers) and filter feeders.

4.0 Statistical analyses

Temporal variation was analyzed with SAS JMP Statistical software by using the abundances

of Polychaetes in different trophic groupings. An analysis of variance to fit means and to test

that they are equal was performed with multiple comparison tests on means, with means

comparison circles and outlier box plots overlaid on each group. The box plots summarize the

distribution of points at each factor level. Each multiple comparison test is represented by a

comparison circles plot, which is a visual representation of group mean comparisons. Overlap

marks show for each diamond and are computed as group mean. Overlap marks in one

diamond that are closer to the mean of another diamond than that diamond's overlap marks

indicate that those two groups are not different at the 95% confidence level.

5.0 Results

The trophic group composition identified the existence of five (5) groups namely Carnivores

(C), Surface Deposit Feeders (SDF), Subsurface Deposit Feeders (SSDF); Herbivores

(HBVR) and Suspension Feeders (SF). The carnivores are represented by the six species of

Lumbrinereis; Lumbrinereis sp.1, Lumbrinereis sp.3, Lumbrinereis sp.4, Lumbrinereis

coccinea, Lumbrinereis latra, Lumbrinereis tetraura, and the two species of Aglaophamus;

Aglaophamus sp1. Aglaophamus sp2. and a Nepthys species; Nephyts sp. Other carnivores

include the two species of Glycera; Glycinde sp and Sigambra tentaculata.




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The surface deposit feeders are represented by Paraleiocapitella sp., Tharynx

dorsobranchialis, Isolda wlydahensis, and Aricidea (Aricidea) sp. nov. and Paraonis sp. The

sub surface deposit feeders are represented by six species namely Cossura sp.2, Scoloplos

(leo) sp.1, Scoloplos (Leo) sp.2, Sternapsis scutata, Notomastus sp.1, and Notomastus sp.2.

The herbivours were Gyptis sp., Lysidice collaris, and Ceratonereis sp. 1, Ceratonereis sp.

The species Malacoceros sp. was the only suspension feeder.

The monthly variation in abundance for all the trophic groups is shown in Fig 2.0. The

monthly variation for carnivore feeding group varied from lowest values in June 2010 to peak

in April 2011. For the Surface Deposit Feeders (SDF) variation was from low in June 2010 to

peak in June 2011. The monthly variation of the sub surface deposit feeders indicates a peak

in abundance between October 2010 and April 2011. Lowest abundance was observed in

June 2010. For the herbivore feeding group significantly low numbers were observed from

June 2010 with peak values in February and April 2011. The suspension feeders showed very

low occurrence values in August 2010 with the highest occurrence value in February 2011.

5.1 Between- Month-Variation

The one way analysis of variance in figs 6-10 shows the graphical scatterplot for each trophic

group with the X axis scaled proportional to the sample size of each month. The Analysis of

Variance uses the Means Diamond option which draws a 95% means diamond for each

group. In fig 6, the mean month scores of the Carnivores appear to be similar for October

2010, February 2011, April 2011, June 2011 all being above the mean while the scores for

June 2010 and August 2010 are the same and appear to be less that the former group. The

boxplots which compare the different months on a numeric response shows that the months

clearly differ in the carnivore abundance per month with variability highest in the month of

October 2010 and the least in the month of June 2010.

In fig 7.0 the mean month scores of the surface deposit feeders for the months of October

2010, February 2011 and June 2011 appear to the be the same as they are above the grand

mean while the mean months scores for the months of June 2010 and August 2010 are same

and appear to be similar that the former group as they are below the grand mean. The




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boxplots shows that the months clearly differ in the surface deposit feeders’ abundance per

month with variability highest in the month of June 2011 and the least in the months of

February and April 2011.

In fig 8.0 the month scores for the months of October 2010, February and April 2011 are

similar being above the grand mean while the mean month scores for June 2010, August 2010

and June 2011 are similar being below the grand mean. The box plots however show

variability in abundance per month to be highest in the month of February 2011 followed by

April 2011 and least in the month of June 2010.

In Fig 9.0 the mean month scores of the herbivores for the months of February and April

2011 are same being above the grand mean while those of the months of June, August,

October 2010 and June 2011 are the same being below the grand mean. The boxplots

however show variability in monthly abundance to be highest in the months of February and

June 2011 with the least in the month of August and October 2010. In fig 10 the Suspension

feeders show a similar mean month scores for June 2010 and June 2011 with an overlap with

the month of Feb 2011 all being above the grand mean. Below the grand mean, the months of

August 2010 and April 2011 are same, overlapping with the month of October 2010 which is

also below the grand mean. The variability in monthly abundance is highest in the months of

February and June 2011 and least in the month of October 2010.

5.2 Within Group Variation

The within-group variation graphical scatterplot for the feeding groups are shown in figs 11-

16. In fig 11.0 the mean month scores for the month of June 2010 for Carnivore feeding

group is significantly different from the other feeding group as shown by both the student t

and Hsu pair comparisons. There is no significant difference in abundance between

herbivores, surface deposit feeders, subsurface deposit feeders and suspension feeders. The

boxplots however show within month variability being highest in surface deposit feeder and

least and similar in carnivore, subsurface deposit feeder and suspension feeder. In fig 12.0 the

mean month score shows a significant difference between the carnivore and the suspension

feeders for the month of August 2010. No significant difference is observed in variation in




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abundance between carnivores, surface deposit feeders, subsurface deposit feeders and the

herbivores.

The within-group month variation mean scores for October 2010 indicate a significant

difference in abundance between the herbivores, suspension feeders and Carnivores. No

significant difference within month variation is observed between the carnivores, subsurface

deposit feeders and surface deposit feeders even though the mean score of the surface deposit

feeders is below the grand mean in the graphic scatter plot. The box plots show that the five

types of feeding groups clearly differ in the within month variation with Carnivores being the

most variable and herbivores and suspension feeders being the least. In fig 14.0 the within

month scores of abundance for February 2011 shows there is significant difference between

carnivores and herbivores, surface deposit feeders and suspension feeders. The box plots

show highest variability in abundance for the subsurface feeders followed by carnivores. The

least within month variability is observed for surface deposit feeders and suspension feeders.

In fig 15.0 the within-group variation means scores for April 2011 show that there is a

significant difference between the carnivores and herbivores, surface deposit feeders and

suspension feeders only. The box plots show high variation in abundance for the carnivore

feeding group followed by the subsurface deposit feeders. Clearly very little variation existed

within the month in herbivore, surface deposit and suspension feeding groups as their box

plots cluster around their individual mean.

In Fig 16.0 the within-month variation mean scores for the month of June 2011 shows that

the carnivore feeding group differ significantly from the subsurface deposit feeders, surface

deposit feeders, suspension feeders and herbivores. The mean scores of within-group

variability for the subsurface deposit feeders, surface deposit feeders, suspension feeders and

herbivores appear to be the same. The box plots show that the five types of feeding groups

clearly differ in the within group variation with surface deposit feeders being the most

variable followed by the carnivores and subsurface deposit feeders with the least variation in

the suspension feeding group.




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6.0 Discussion

The study has shown evidence of monthly variability within-feeding guilds. However the

variability response for the feeding groups does not show any pattern of seasonal variation as

there is no significant difference between the wet season months of June, August and October

and the dry season months of February and April. There is however a consistent pattern of

significant difference between the carnivore feeding group and the other four feeding guilds

in June 2010 and 2011, three feeding groups in February and April 2011; two feeding groups

in October 2010 and one feeding group in August 2010.

The results of this study seem to agree with those reported by Bianchi and Morri (1985) for

feeding groups found in the M. galloprovinciallis assemblage in a coastal deltaic assemblage.

Their results showed that detritivorous (deposit feeders) Polychaetes constituted 18% of the

total species, and filter feeders 10% whereas macrophagous (carnivores) exceeded 62%.

Similarly this pattern is followed in this study where the detritivores (Surface deposit feeders

and sub-surface deposit feeders) constitute 23% and 11% respectively whereas the filter

feeders and Herbivores constituted 2% and 10% respectively and the Carnivores with the

highest proportion of 54%. Among the Carnivores the Lumbrinereis tetraura account for

more than 34% of the total variation in this group of 14 species while within the subsurface

deposit feeders of 6 species Scoloplos(leo) sp.1 account for more than 40% of the variation

observed in the group. Within the surface deposit feeders comprising of 5 species Aricidea

(Aricidea) sp. nov. and Tharynx dorsobranchialis account for over 50% variation while

within the herbivore feeding guild Ceratonereis sp.1 and Gyptis sp. account for over 60%

variation evident.

The consistently high variability in the carnivore feeding guild is indicative of the fact that

other biotic and abiotic factors are regulating the observed populations since there is a stable

salinity resulting from the absence of dilution effects of freshwater streams discharging into

the Bonny River. Documented evidence shows that the dominance of carnivorous

polychaetes have shown a correlation with coarse sedimentary particles (Paiva (1993), Muniz

et al. (1998) and Muniz and Pires (1999). The preference of carnivores for coarser sediments

with low levels of mud and clay is also well known (Maurer and Leathem, 1981; Gaston,

1987; Gaston and Nasci, 1988; Tena et al., 1993).




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Coarser sedimentary particles which have large interstices among grains can create space

enough to favour the mobility and feeding of carnivores, abundance of prey and oxygenation

of the sediments (Fenchel, 1970). This observation correlates well with the anthropogenic

activities at the mouth of Bonny River where three major oil and gas firms (Shell Petroleum

Nigeria Limited, Nigerian National Petroleum Company and Mobil Producing Nigeria

Unlimited) dredge the channel to periodically enable them load oil and gas products. This

consistent maintenance dredging is likely to maintain continuously the settlement of coarser

sediments. The absence of low fine grained sand containing high organic matter content

would limit the abundance and distribution of the deposit and the suspension feeders.

The present study has shown that the feeding guilds of Polychaetes can be a good indicator of

environmental quality as they provide signals of any changes that might be taking place.

Attention is therefore needed in understanding the structure of the Polychaete communities at

the Bonny bar through many successional cycles in order to evaluate many of the biological

variables (predation, competition, food availability) that influence changes in community

structure under different stress conditions . This is because they live in the narrow surface

layer of the substrate and are the first organisms to be influenced by any environmental

changes.




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References

1. Bianchi, N.C. and Morri, C. (1985). Policheti come descrittori della strutura trofica

degli ecosistemi marini. Ocbalia 11: 203 -214.

2. Chindah, A. C. and Osuamkpe, A. (1994). The fish assemblage of the lower Bonny

River. Afri. J. Ecol. 32, 58 - 65.

3. Day, J.H. (1967). A Monograph of Polychaetes of Southern Africa. London (British

Museum of Natural History). Pt 1. Errantia 1-458: Part 2: Sedentaria: 459-

878.

4. Ekweozor I K E Ombo, E. I. and Ugbome, A. P. (1989). The effect of chronic oil

pollution in the central Bonny estuary. In: The petroleum industry and the

Nigerian Environment. Proc. of 1987, 198 – 207.

5. Fauchald, K. (1977). The polychaete worms, definitions and keys to the orders,

families and genera. Natural History Museum of Los Angeles County: Los

Angeles, CA (USA) Science Series 28:1-188.

6. Fauchald, K. and Jumars, P. A. (1979). The diet of worms: a study of polychaete

feeding guilds. Oceanogr. mar. Biol. a. rev., 17:193-284.

7. Fenchel, T. (1970). Studies on the decomposition of organic detritus derived from the

turtle grass Thalassia testudinum. Limnol. Oceanogr., 15(1):14-20.

8. Gaston, G. R. (1987). Benthic polychaeta of the Middle Atlantic Bight: feeding and

distribution. Mar. Ecol. Progr. Ser., 36:251-262.

9. Gaston, G. R. and Nasci, J. C. (1988). Estuarine macrobenthos in Calcasieu,

Lousiana: community and trophic structure. Estuaries, 11:201-211.

10. Hart, A. I. and Chindah, A. C. (1998). Preliminary study on the benthic microfauna

associated with different microhabitats in mangrove forest of Bonny estuary, Niger

Delta, Nigeria. Acta Hyrobiol., 40 (1): 9 – 15.

11. IPS (1989). Environmental data acquisition at some NNPC Operational areas. Vol.III

Biological studies. Rivers State University of Science and Technology Port Harcourt

Nigeria. Institute of Pollution Studies, SUST/IPS/TR/89/03.393pp.

12. IPS (1990). Baseline ecological studies of Bonny south (field) location. Final report

Rivers State University of Science and Technology Port Harcourt Nigeria.Institute of

Pollution Studies, RSUST/IPS/TR/89/02, 288pp.




809

13. IPS (1992). Environmental Impact assessment study of the nitrogenous fertilizer

factory complex, Onne, Rivers State Nigeria. Rivers State University of Science and

Technology Port Harcourt Nigeria Institute of Pollution Studies. RSUST/IPS/91/06,

411pp.

14. Muniz, P.; Sumida, P. Y. G. and Pires-Vanin, A. M. S. (1998). Trophic structure of

polychaetes in two bays of the southeastern Brazilian Coast (Mar Virado and

Fortaleza, Ubatuba, São Paulo). Ocbalia, 24:39-53.

15. Muniz, P. and Pires, A. M. S. (1999). Trophic structure of polychaetes in the São

Sebastião Channel (Southeastern Brazil). Mar. Biol., 134(3):517-528.

16. Maurer, D.; Leathem, W. and Menzie, C. (1981). The impact of drilling fluid and well

cuttings on polychaete feeding guilds from the US Northeastern continental shelf. Mar.

Pollut. Bull., 13:342-347.

17. NEDECO, (1961). The waters of the Niger Delta. Report of an investigation by

NEDECO (Netherlands Engineering consultants). The Hague, pp: 210-228.

18. OMBU, E.I (1987). The impact of the Okrika oil terminal on the littorial benthos of

the central Bonny estuary, Nigeria. M. Phil. Thesis Rivers State University of Science

and Technology Port Harcourt Nigeria. 246pp.

19. Paiva, P. C. (1993). Trophic structure of a shelf polychaete taxocoenosis in southern

Brazil. Cah. Biol. mar., 35:39-55.

20. RPI/NNPC (1985). Environmental Baseline Studies for the establishment of control

criteria and Standards against petroleum related Pollution in Nigeria. South Carolina,

USA, XIII 45pp.

21. Tena, J.; Capaccioni-Azzati, R.; Torres-Gavila, F. J. and Porras, R. (1993).

Anélidos poliquetos delantepuro de Valencia: distribuición y categorías

tróficas. Publ. esp. Inst. Esp. oceanogr., 11:15-20.




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Table 1a .Mean lengths of C. gariepinus exposed to different formulations of insect (B.

alcinoe)

Diets/Pond Initial

length

(cm)

Month 1 Month 2 Month 3 Month 4 Month 5 Month 6

BALF alone 3.2

7.95 9.28

ARAC flour

a;lone 3.6 6.89 9.10

BALF

+ARAC flour 3.5 8.98 10.84

BAL flakes

alone 3.6 8.94 10.86

BAL +

ARAC pellets 3.5 8.98 10.84 12.4 16.7 18.6 18.3

WHOLE

FORM of

BAL alone

3.8 8.94 10.86 13.7 14.9 17.8 17.5

ARAC pellets

alone 3.6 6.89 9.10 14.2 14.2 16.7 17.5

Table 1b .Mean weights of C. gariepinus exposed to different formulations of insect

(B.alcinoe) diets

Diets/Pond Initial

weight

(g)

Month 1 Month 2 Month 3 Month 4 Month 5 Month 6

BALF alone 1.29 2.58 3.50

ARAC flour

a;lone

1.35 2.13 3.20

BALF

+ARAC flour

1.34 3.65 5.42

BAL flakes

alone

1.28 2.80 4.57

BAL pellets +

ARAC pellets

1.25 3.65 5.42 10.88 12.54 15.4 15.8

WHOLE

FORM of

BAL alone

1.34 2.80 4.57 13.7 14.9 17.8 17.5

ARAC pellets

alone(control)

1.31 2.92 4.18 14.2 14.2 16.7 17.5




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Table 2a. Morphometric measurements of 6 weeks old fingerlings of C. gariepinus bred on

different diets in eight artificial ponds n=50 per diet/ pond.

Mean lengths / widths S.E.

DIETS /PONDS Percentage of B.

alcinoe

Length (cm) Weight (g)

B.alcinoe larval

flour(BALF) alone

100 6.84 0.46 5.67 0.70

ARAC flour alone 0 5.32 0.51 3.63 0.55

BALF +ARAC

flour

50 6.98 0.53 6.38 0.54

B.alcinoe larval

flakes alone

100 7.68 0.48 4.87 0.61

Table 2b. Morphometric measurements of 24 weeks old C.gariepinus (n=50 per diet/pond)

DIETS/POND % of B.alcinoe Length (cm) Weight (kg)

BAL +ARAC

pellets

50 80.43 1.06 2.46 0.84

Whole forms BAL

alone

100 89.73 0.97 2.07 0.76

ARAC pellets

alone

0 81.58 0.83 1.75 0.82

Control (ARAC

diets alone)

0 80.34 1.03 1.97 0.89




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Table 3. Specific Growth Rate (SGR) of C. gariepinus exposed to different diets

formulations.

Diets Month

1

Month 2 Month 3 Month 4 Month 5 Month 6

B.alcinoe

larval

flour(BALF)

alone

7.5 3.3

ARAC flour

alone

5.0 4.4

BALF

+ARAC flour

10.9 4.3

B.alcinoe

larval pellets

alone

8.5 5.3

BAL +ARAC

pellets

11.6 4.3 7.6 1.5 2.2 0.3

Whole forms

BAL alone 8.0 5.3 11.9 0.9 1.9 0.2

ARAC pellets

alone

8.7 3.9 13.3 0.0 1.8 0.5

Fig 1a Mean Weight Distributions for Juvenile fishes Fig 1b. Mean Length Distributions for Juvenile fishes

3

4

5

6

7

8

9

10

11.01 .05.10 .25 .50 .75 .90.95 .99

-2 -1 0 1 2 3

Normal Quantile Plot

Moments Mean 7.297619

Std Dev 2.9291926 Std Err Mean 0.6392022 upper 95% Mean 8.6309715

lower 95% Mean 5.9642666 N 21

1

2

3

4

5

6.01 .05.10 .25 .50 .75 .90.95 .99

-2 -1 0 1 2 3


Moments Mean 2.8833333 Std Dev 1.4131289

Std Err Mean 0.30837 upper 95% Mean 3.5265819 lower 95% Mean 2.2400848

N 21




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Fig 2a. Mean Weight Distributions for adult fishes Fig 2b. Mean Length Distributions for adult fishes

Fig 3a. Analysis of Variance of Length by Diet for Juvenile fishes 6 weeks old

12

14

16

18

20.01 .05.10 .25 .50 .75 .90.95 .99

-2 -1 0 1 2 3




lower 95% Mean 14.732671 N 12

10

12

14

16

18.01 .05.10 .25 .50 .75 .90.95 .99

-2 -1 0 1 2 3




lower 95% Mean 13.739649 N 12

Lenght

3

4

5

6

7

8

9

10

11

AR

AC

Pellets

AR

AC

flo

ur

BA

L w

hole

BA

LF

BA

LF

Fla

kes

BA

LF

+A

RA

C P

ellet

BA

LF

+A

RA

C flo

ur

Diet

Each Pair

Student's t

0.05

Analysis of Variance

Comparisons for each pair using Student's t




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Fig 3b. Analysis of Variance of Weight by Diet for 6 weeks growth of Juvenile fishes

Length

12

14

16

18

20

ARAC Pellets BAL whole BALF+ARAC Pellet

Diet

Each Pair

Student's t

0.05

Analysis of Variance Source DF Sum of Squares Mean Square F Ratio Prob > F Diet 2 1.471667 0.73583 0.1465 0.8658 Error 9 45.217500 5.02417

C. Total 11 46.689167

Two Way Anova(Means Comparisons)

Comparisons for each pair using Student's t

t

2.26216 Abs(Dif)-LSD BALF+ARAC Pellet BAL whole ARAC Pellets

BALF+ARAC Pellet -3.5854 -3.0604 -2.7354 BAL whole -3.0604 -3.5854 -3.2604 ARAC Pellets -2.7354 -3.2604 -3.5854

Positive values show pairs of means that are significantly different.




815

Fig 4a. Analysis of Variance length by diet for growth of adult fishes 24 weeks old

Weig

ht

10

12

14

16

18


Diet

Each Pair

Student's t

0.05

Analysis of Variance Source DF Sum of Squares Mean Square F Ratio Prob > F Diet 2 12.624067 6.31203 1.5227 0.2694

Error 9 37.307400 4.14527 C. Total 11 49.931467

Means Comparisons Comparisons for each pair using Student's t

t

2.26216

Abs(Dif)-LSD BAL whole ARAC Pellets BALF+ARAC Pellet BAL whole -3.2567 -2.9317 -0.9367

ARAC Pellets -2.9317 -3.2567 -1.2617 BALF+ARAC Pellet -0.9367 -1.2617 -3.2567

Positive values show pairs of means that are significantly different.




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Fig 4b. Analysis of Variance of Weight by Diet for growth of adult fishes 24 weeks old

Fig 5a. Specific Growth Rate of diet treatment on Juvenile fishes (6weeks growth)

Fig 5b. Specific Growth Rate of diet treatment on adult fishes (24 weeks growth)

JUV_

SGR

3

4

5

6

7

8

9

10

11

12

ARAC

Pel

lets

ARAC

flou

r

BAL

who

le

BALF

BALF

Fla

kes

BALF

+AR

AC P

elle

t

BALF

+AR

AC fl

our

Diets

Analysis of Variance Source DF SS Mean Square F Ratio Prob > F Diets 6 15.97 2.66167 0.239759 0.94905 Within 7 77.71 11.1014

Total 13 93.68 7.20615 Negative Variance Components were set to zero

Adul

t_SG

R

-2

0

2

4

6

8

10

12

14


Diets

Analysis of Variance Source DF SS Mean Square F Ratio Prob > F

Diets 2 2.281667 1.14083 0.042532 0.95855 Within 9 241.4075 26.8231 Total 11 243.6892 22.1536

Negative Variance Components were set to zero

Polychaete feeding Guild

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