447
Ncrherlands Jou mal of Zoo/ogy
49 (3): 189-206 ( 1999)
THE EPIBENTHOS OF THE BACKWXfERS OF A TROPICAL
MANGROVE CREEK (TUDOR CREEK, MOMBASA, KENYA)
by
ENOCK O. WAKWABI
1•2·*
and JAN MEES 2
( 1 Kenya Mnri11e & Fi.l'hcric.l' Rcscarch !nstitutc, l'O. Box 81651, Moni/){1,\'0, Kenra;
2 Marine /iiologY Sectio11. Zoo/og_,. lnsriturc•, Uni1•crsil1' of'Gcnl, K.!" Lcdcgondstmor
35. /J-'){)()() Gcnr. He/giton)
ABSTRACT
The l~pihcntho~ or the backwatcrs nr Tudor crc•ck (Mnmbasa. Kcny;i), a mangn>VL'bi1i'dCi'Cd ><:aS111lal c·,.;tuat-y. w;1s sampkd i'ortnightly with a hcam trawl i'nHII M;1y 1')95
to April 1996. A l<,tal of (1,)96 specimens was collcctcd in 96 tows. Almost (13% of
Ihcsc specimens bclongcd to 7'2 spccics or tclcost lish (in 37 ramilics). Pcnacid (4
spc.:ics) and <.:arid\:<lll shrimp conslilutcd 2701.• and X% or the total cal ch rcspcclivcly, wh ile
stomatopods and squids wcre quite rare. At family lcvcl, Pcnaciclac contributcd most to
the total c:uch. Gobiidac (15%), Lutjanidac (9%), Plotosidae (9%), Acropomatidac (6%),
Gcrrcidac (5%), and Synodontidac (4%) wcrc the most import<lllt lish familics. Gobiidac
was the most diverse family with 8 specics, followed by Apogonidac and Lutjanidae with 5
species each, and Penaeidae with 4 species. Yongeichthys 11ebulosus (Gobiidac), Penae11s
1110/IOdon, P. semi.lulcaws and Metapenaeus monoceros (Penaeidae), Plotosus lillea/11.1'
(Piotosidae), L11tjanus .fi;/viflamma (Lutjanidae), Acroponw japonictun (Acropomatidae),
Gcrres oycno (Gerreidae), and Saurida undosquamis (Synodontidac) werc !he dominant
species (each contributecl for more than 4% to the total catch).
A TWINSPAN of the catch data iclentiticcl three monsoon drivcn communities. Pcll(tells
monodon. Lllfjanus .fulviflamma and Gerres riyena wcrc the dominant specics in the dry
period (January to April), while P. semisulcatus and Caridea dominatcd the community in
the long rainy season (l'day to August), and Acropoll/.11 japonicwn and Plotosus !i11eatus
m:re important during the short rains (Septcmber to Dcccmbcr). Mctapcnacl/s 11/0nm·cms
was abundalll in al! seasons and )·imgcichthys nc/Julo.lïiS reached high dcnsitics in both
short rainy and dry seasons. The short rains community had the highcst numbcrs of spccies
and dcnsiti.:s. whilc thosc nr Ihc long r;1iny scason were lowcst. The thrce communities
bad very strong dominance of only a f'cw spccies. conforming to the general observation
tint tropical estuarinc or coastal cco~ystcms tend to be very diverse but with very low
densitics for the majority of specics. The restricted si ze ranges for ali individuals caught
during this study may be duc to two proccsses: sckctivity of the gca1· and/or dynamic
n:p!an:mcnt or the pupulations thnHtgh scasonal rccruitmcnt and fast si;.e progression. Ali
individuals co!lectcd du ring this study were juveniles. This t'act and the ohservcd monihly
sizc distributions sur,gcsl !hat most spccies utilise~ the arca as :1 nursery.
KEY WORDS:
cpibcnthos. backwatcrs, tropical mangrove ercek. scasonal çommunitics,
di1<:rsity.
For communications and ollpl'illls.
© Koninklijke
Brill NV. 1.l':ickn. 1999
Reprinted with kind permission from Brill Academie Publishers
448
190
WAKWABI & MEES
INTRODUCTION
Tudor creek is located to the Northwcst of Mombasa Island, Kenya (4°S,
40°E). It ex tends some 10 km in land, has a surface of approximately
20 km 2 at mean sea leve] and comprises shallow channels, mudbanks
and mangrove forcsts (WAKWABI & JACCARINI, 1993). The seasonal
pattern of the equatorial currents (the South Equatorial CuiTent and
the Equatorial counter Current) across the western lndian Ocean, and
the reversing longshore East African Coastal Current together with the
monsoon winds (Northcast monsoons in Novcmbcr to March and the
Southcast n1onsoons in April to Octobcr). inllucncc the magnitude and
vdocity or the tidal currcnls in Tudor crcck (NORCUNS u u, 1<J75) and the
rainfall seasonality in the region. This influence predetermines the tidal
flux. and productivity on Tudor creck (WAKW/\131 & Ji\CC't\RINI, 1993).
The crcck (Fig. 1) can be diviclcd into thrcc sections: a marine mouth
area, the middle crcck arca, and the upper hinterland end. The mouth
arcais a decp (ca 30 m) rivcr-like channel \Vith extensive rocky substrata
and unvcgetatcd sandy sediments and banks, rccciving direct marine
in11uence through tidal fluxing. The upper end is shallow (gcncrally
< 1 m) and split into different channels, some cnding into river mouths.
Three seasonal rivers (Kombeni, Tsatu and Mtsapuni) flow into the
creek. This upstrcam arca is bordered with a dense mangrove forest
(mostly Rhyz.ophora mucronata Lamk., and A viccnio marina (Forsk)
Vicrh.) on extensive silty mudbanks and muc!flats. The surl'acc watcr
salinity and temperature berc vary scasonally, diurnally and tidally; and
the arca supports brackish to freshwater spccics. In the middle arca,
the creek is not split into different channels. 1! is on average 1-2 km
wide but shallow ( < 5 m) cxcept for the decp ( > 20 m) mid channel.
Tidal influence is greatly rcduced, and salinity (34-36 psu), surface
water temperature (24-32 °C), dissolved oxygen concentration (78-84%
saturation) and turbidity ( 1.5-2.5 m secchi dise dcpth) arc qui tc different
from the respective parametcrs at the mou th arc (i. c., 35 psu, 25-29 °C,
92-95% and 3-6 111, rcspectivcly) (LITTLE er al. 19H~. WAKWI\Bl &
JACCARINI, 1993). This study focuses on the middle arca of the crcck,
more specifically on two shallow channcls with soft silly substratcs
that are bordered with dense mangrove forcsts . lts selections was basee!
on earlier observations on the distribution of freshly scttlccl penacid
postlarvac and juveniles: this arca was found to be an important nursery
arca for severa! spccics of pcnacids and - probably - tclcosl fish
(WAKWAI31, 1996).
Rescarch findings have consistcntly pointcd to the important rolc shallow arcas and estuarics play in the carly lifc histories or different marine and brackish organisms (c.g., LAEGDSGAARD & JOHNSON, 1995;
449
EP!BE!\'THOS TUDOR CREEK. MOMBASA. KENYA
191
POLL;\RD & HANNAN, 1994; WILLIAMSON cl of., 1994; and 13LABER
ct al .. 1992 on the Austra1ian mangrove associated systems; SCHMITTERSOTTO & GAiVIBOA-PEREZ, 1995 on the Yucatan pcninsular, Mexico;
HUSS:\IN & SAI\·IAD, 1995 and FOUDA & AL-MUHARRAMI, 1995
on the Arabian sea coasts of Pakistan and Oman; and SEDBERRY &
CARTER, 1993 on the tropical laggons Belize, Central America; are but
few cxplicit references to the nursery rolc of mangrove lined coastal
eeosystems). GILLANDERS & WHITFIELD (1997), HARRIS & CYRUS
(1996), CYRUS & FORBES (!996), KNEIB & KNOWLTON (1995).
HERKF (1995). and WI!!Tl'IELD & KoK (1992) arc valuahlc accounts
on the importance of cstuarics as nursery grounds. Rcccntly. MARGUILLIER ct al., (1997), DE TROCJ-1 ct al. (1996), and KIMANI ct al. (1996)
reportee! on the trophic rclationships, and the fish communitics of Gazi
Bay. Keny:1. They seem to agree on high diversity and suggcst the irnportanœ of the mangrove - scagrass bcds - coral rccf interlinkagc to
juveniles of marine fishes on the bay. The only stucly on the Jish fauna
of Tudor creek is a beach seine and plankton survcy reportee! in LITTLF:
etal. (1999). \VAKWABl (1988) and WAKWABJ & JACCARINI (1993) focused on the penacids. Early postlarval and juvenile fish were obscrved
to migrate into the crcek. The species composition cliffercd significantly
between the mouth arca and inner rcaches of the crcck, but no clear
temporal·variation in the community structure was obscrvecl. Likc many
other studics in estuarinc areas (QUINN, 1980), the fish community of
Tudor creek was found to be very diverse but with very fcw dominant
species. The crcck was found to be an important nursery and feecling
ground for- often commercially important- teleost fishcs (espccially
carangids, clupeids, haemulids, lethrinicls, lutjanids and siganicls) (LITTLE ct a/., 1988) and penaeicls (WAKWABI. 1988; WAKW/\131 & .TACCARIN!, 1993).
The objectives of this study wcre: ( 1) to describe the structural chantcteristics (spccies composition, density, divcrsity, sizc composition) of the
cpibenthic community (i.e. demersal fish and invcrtebratcs) of the shallow,
mangrove-bordered areas in the middle rcaches of the creek and (2) to investigatc scasonal variation in tllcse communitics.
MATERIALS AND METHODS
A 1.5 m bca111 trawl with a 2 111111 mcshcd inncr bag was towcd on foot
by wading through shallow shore waters of 0.5-1 m dcpth in two adjacent
tidal channcls (Fig. 1). Samplcs wcre al ways taken during daytime from
2 hours bcfore to 2 hours aftcr low water spring tide betwccn May
450
192
WAKWABI & MEES
~
Mudflats
Scale :
Fig. !.
0
1 Km
i\'lap of Tudor crcck showing the tidal nats/mangrove enver. the scasonal rivers
("l'satu. Kombcni and Mtsapuni) and the sa111 pling sites 1 and Il.
1995 and April 1996. Two replieatc tows wcrc made in cach channel
making a total of four tows on each sampling date and a total of cight
tows for cach mon th, cxccpting .June 1995, August 1995 and February
1996 whcn only one spring tide was samplcd. On each occasion the net
was lowcd l'or about 20 111, swccping a surraœ arca
approximalely
30m 2 .
or
451
EPIBEi\'THOS TUDOR CREEK. MOMBASA.
KENYA
193
In the field. ali animais caught in the net were sortecl out of the debris
and preservee! in a 8% fonnaldchyde-scawatcr solution for storage. In the
laboratory. the animais werc Iater s01·ted, idcntificd. counted and measurcd
to the nt:arest 1 mm. Ail fish and penaeids werc identified to spccies leve!
using the kcys provided by M OTOH (1981 ), SMITH &HEEMSTRA ( 1986),
FISCHER & BIANCHI (1984) and BIANCHI (1985). Ali other invertebratc
groups. together accounting for lcss than 10% of the total catch. wcre
only identilied to higher taxonomie lcvels: Stomatopoda. Ccphalopoda
and Caridca were rccorded as such. Standard body lcngth was measured
for ali tishcs (distance from the tip or the snout to the base of the tai!).
exœpt for representatives or the Plotosidac (total length). Total lengths
wcre laken for ail crustacca (stomatopods, penaeid and caridean shrimp):
distance from the tip of the rostrum to the end of the telson. For squids,
the total body length was measurecl excluding the arms.
Prior to multivariatc analyses, the data of each sampling date werc
poolcd (4 samplcs: 2 stations and 2 trawls per station) and fnurth-root
transformee!. Rare species, i.e. species constituting Jess than 0.5% of the
total catch of any one sam pic, were eliminated from the data ma tri x. Thesc
reduced poolcd catch data were then subjected to TWINSPAN (Two
Way Indicator Species Analysis, a divisivc classification technique) and
a corrcspondcnce analysis (an indirect ordination technique). Arter the
identification of seasonally defined communities. thesc were charactcrisecl
by their average density and diversity. Diversity was calculated as the
Hill's diversity numbers of the orcier 0 and 1 (HILL, 1973 ):
No is the number of species in a sample;
N 1 is the equivalent to the Shannon-Weaver cliversity index, i.e. ,
N 1 = exp(H') with H' = - :Lp;(logp;), and p; = N;/N 1, where N; is the
abunclance of the i111 species in the sample and N1 is the total abundancc or
the ~ample.
RESULTS
Spccics co!llf!Osirion
For a complete species list and the total numbers of individuals caught
Cor each spccies or taxun pcr sampling date \Vc ret"cr to the Appendix. The data rcported in this study arc summarised and comparcd with
thosc rcportecl by LiTTLE et al. ( 19RR). From a total of nincty six tows,
6.396 specimens wcre collected, belonging to 79 spccics or higher taxa.
4023 (62.9%) of the specimens belnngcd to 72 spccics or tcleost tish
(in 37 families). Penaeid shrimps (4 spccics) and cariclean shrimps constitutcd 27.45% and 8.02rf?! of the total catch respcclivcly, whilc stomatopods and cephalopods wcrc qui te rare (0.36% and i .27% respective! y).
452
194
\VAKWABI & MEES
At the family leve!, Penaeidac contributed most to the total catch. Gobiidae ( 15.35% ), Lutjanidae (8.65% ), Plotosic!ac (8.61% ), Acropomatidac
(6.24%), Gerreidac (5.00%), and Synodontic!ac (4.32%) wcre the most
important fish families. Gobiidac was the most diverse family with 8
specics, followcd by Apogonidae and Lutjanidac with 5 species each, and
Penaeidae with 4 species. Yongeichthys nebufosus (Gobiidae), Perzaeus
nwnodon, P semisu{cotus and Mewpenaeus monocems (Penaeidae), Pfotosus lineatus (Piotosidae), Lutjanusfulvijiamma (Lutjanidae), Acropoma
japonicum (Acropomatidae), Gerres oye11o (Gcrreidae), and Sourido undo.\<flWIIIÎs (Synodontidae) were the dominant species: each contributed
for more than 4% to the total catch.
Seasonality
The catch in number of individuals and species was generally quite
variable. On a monthly basis (Appendix), the highest number of species
(41) was recordee! in November and the lowest (14) in June. The rest of the
months bad an intermediate number of species, varying between 18 and
35. In the short rainy season (September through December) the mean
number (±SE of the mean, N = 4 months) of species (34.25 ± 2.29) was
high as compared to the dry season (January through April: 29.25 ± 2.95)
and the long rainy season (May through August: 22.0 ± 3.56). Mean
monthly density (catch in numbers per 30m 2 ± SE of the mean, N = 8
tows) was lowest ( 15.75 ± 0.02) in August and highcst ( 123.63 ± 42.19)
TABLE 1
Catch rates (numbers caught in a standard :10 m2 tow) of the epi benthos collectcd during
th~ 111\li1thly heam trawl study or the hackwaters of Tudor cree k. Mombasa, Kenya in May
1095 throLJgh April 1996 ( tneilns cstimatcd on cight tows per llHlillh).
Mon th
Total catch
Catch/:10 m2 ( :1: SE or mean)
1\lay
(J2X
1:15
50S
126
540
<)55
614
500
620
9X<J
563
222
7S.50 :L 17.3S
lh.SS ± X.40
6.1.50±21.54
15.75 ± X.02
67.50 ± 20.21
119.:1X ± :16.41
7CJ.75 ± :11.25
62.50 ± 17.71
77.50 ± 17.99
12:1.63 ± 42.11)
70.:1R ± 19.40
27.75 ± 12.77
<))
.lune 95
.July 95
August <)5
Scptcmber 95
Octohe1· 95
Novcmhcr 95
Dccember <)5
Januury 96
February 96
Mareil 96
;\pril 96
453
195
EPI BENTHOS TUDOR CREEK, MOMBASA, KENYA
TABLE 2
The minimal (min). maximal (max), modal (M) and the maximum atlainahle size (!.X)
sizcs (nlln SL) of the abundanl and common speeies and/or taxa caughl (with > 0.3% of
th.: total catch) cluring the bcam trawl study (May 1995 through April 1996) on Tudor
cree k.
Species
Abbrevation
Numbcr
min
max
M
Spratdloides delicatulus
Plorosus lineatus
Saurida undo.HJIIal/lis
Hemirhamphusj{1r
Syngnathus acus
Cociclla crocodila
Apogon /ateralis
AcTOf>mnajaponicum
1'/c,·t,Jr/nïl<'hlls gcll<'riJIIIS
Luzianus .fitli·Z(lanuna
Monodactylus a1;~enteus
Gcrres oycna
Leiognatl111s equula
Caranx ignobilis
Valcmugi/ sa he li
SJJhyraena jd!o
Pl.'troscrites sp
Amhfygohius a//Jilnaculotus
0/igo/epis kcicnsis
Yongcic/11hys nelm/osus
Bot hus nwncus
Spra deli
Plot line
Saur undo
1-!cmi far
Syng acus
Coci croc
Apog latc
Aero japn
Pkc !!ale
Lutj fulv
Mono argc
GerT oyen
Leio equu
Cara ingo
Yale sahc
Sphy jell
Petr spec
Ambl albi
Olig keic
Yong ncbu
Both mane
Cari mix
Meta mono
Pcna indi
Pcna mono
Pcna scmi
Squi mix
112
552
277
65
19
9
61
400
1(l
547
74
309
65
5
21
182
21
21
162
747
43
625
625
107
727
297
76
16
20
20
17
84
63
8
9
14
14
10
12
10
31
23
21
17
17
15
11
23
39
155
125
135
151
80
85
16-20
71-75
46-50
21-25
Cari dea
J\1etapenacus monoceros
Penocus indicus
Penaeus nwnodon
Pcnaeus sc111isulcatus
Ccphalopoda
JO
15
IX
8
13
7
88
46-50
16-20
70~*
300**
450~*
440~*
300*
500*
lOO*
200*
500~*
l)l)
105
36
63
42
50
39
20
44
35
110
100
!55
67
105
17R
152
130
144
U\
36-40
16-20
31-35
16-20
350**
250~*
250**
420**
1650~*
16-20
26-30
500~*
1500~*
70*
IXO*
46-50
16-20
16-20
56-60
31-35
51-55
56-60
26-30
70*
IRO*
420*
JO~
200~
230~
340*
230~
900~
~ and * n:spcctiv..:ly. denote BIANCHI (1985) and/or SMITtt & Ht'EMSTRi\ (1986) as
sour<:<: of the LS.
in February (Table 1). The short rainy season again had a higher mean
density (652.25 ± 103.6) compared to the long rainy season (394.25 ±
1:?.8.7) and the dry season (598.5 ± 157.9) based on the poolcd monthly
totals (N = 4 months).
Size composition
The minimum and maximum sizcs rccordccl for the most abundant and
charactcristic spccies rccordcd in this study arc presentee! togethcr with
454
196
WAKWABI & MEES
their adult size in Table 2. lt is apparent thal ali landed individuals were
juveniles. Ali inclividuals eaught in this stucly fall within restrictcd sizc
ranges which may rclkct on the selcctivity of the gcar. This limitcd size
range may also suggest an apparent restriction of the !ife stages of the
specics in these backwatcrs pointing more to a transitional population as
opposee! to a resiclential one. Note that even the gobies, which should have
largcr sizc ranges in this arca. display the same limitcd size range. Since
this study did not undertakc selcctivity assessment of the uscd gear, it may
not be casy to full y explain the observee! size ranges. The transition pattern
may howcvcr strongly suggest the role or thcsc backwaters as nursery
grounc!s, espccially for the penacic!s and for most commercially important
tish speeies.
Mu!ril·oriorc ono!rscs
Thrce distinct epifauna communities, clcarly corresponding to the "short
rains-dry-long rains" seasonal pattern, emcrgcd from the TWINSPAN
(Fig. 2) and corrcspondcnce analysis (Fig. 3a. b). ln the lirst TWINSPAN
division , ali long rain samplcs are split off from the rest, with Meropenaeus nwnoceros, Caridca, Penaeus semisu!carus and Lu~janus .fit!vi.flamnw as indicator specics. ln a second division. the dry season samplcs
Meta mono (4)
Lutji'Jtv (4)
Cari(4)
Pana semi (4)
Pena indi (1)
Lulj fu/v (5)
Pena mono (1)
A10
810
A04
804
A03
803
DRY SEASON
A01
A02
801
811
A09
A12
809
812
A11
SHORT RAINS
AOS
A07
BOS
807
802
WET SEASON
Fig. 2. A dendrogram from the Two Way lndieator Speeies /\nalysis (TWINSP/\N)
trcatmcnt of the epibcnthos data eollcctcd during the bcam trawl study on Tudor crcck.
:'vlombasa. Kenya in May 1995 through April 1990. A and B denote lirst and second
spring tidl! of till~ month. Monlh., wcrc progrcssivcly dcnolcd hy 1 for .lanuary to 12 for
Dcccmbl!r. Nam\:s of sp~.:cics and taxa arc ahhrcviatcd as in Table 2. The numhcrs against
the indicator taxa dc110tc the eut kvcl.
455
EPIBENTHOS TUDOR CREEK, MOMBASA, KENYA
197
TABLE 3
Estimatcd ~casonal 1-!ill 's divcr,ity indices (No and Nt) on the epi benthos collcctcd with a
bcam u·,twl t'rom Tudor crcck, Mombasa Kenya. in May 1995 through April 1996. Details
in the tcxt.
Season
Nt
No
H'
NI
Long r•lins
Short rains
Dry
1269
2607
2394
:19
67
0.21 x
0.162
0.191
1.24:1
1.176
1.21 1
4~
arc scparated from the short rains samplcs. P 11/0fl(}(lon, P indicus and
L. fullïfianuna arc indicator specics for dry scason. The threc communities
are characterised in figures 3 and 4. The dry scason (.January-April) community was charactcriscd by high dcnsitics or Penoeus mmwdon. Lwjonus
.fiilv!Jioninw and Gcrres oycna. The long rains (May-August) community
was dominated by Penaeus semisulcatus and Cariclea, while the short rains
(Scptcmber-Deccmbcr) community was dominatccl by Ac.'I'Of)(J/1/([ japonicwn and P!otosus lineotus. l'vfetapcnaeus monoceros was abunclant in ali
seasons and Yongeichthys nebulosus reachccl high dcnsitics in both short
rains and dry seasons. The short rains community had the highest numbcr
of species (No) and density, though the diversity index (N 1) was rather
uniform ancllow for ali the seasons (Table 3). The thrce communities arc
therefore basee! on the seasonal occupancy of a fcw spccics which rccruit
in this arca only during a limited period of stay determinee! by the seasonal
and temporal environmental fluctuations in the crcck.
DISCUSSION
The recordee! numbers or 72 fish spccics in 37 tclcosl ramilies arc
comparable to thosc rccordcd by LITTLE ct a{. ( 1988) (8~ spccics
in 38 familics). Fivc tclcost ramilics (Acropomatidac, Monodactyliclac,
Percorphidac. Scrranidac. and Dactylnpteridac) caught in this study wcrc,
lhlWcvcr. not rcpnrtcd by LJTTLL'. ct al. ( 19~8). This difference is carried
t'urthcr al the sjk'cks lcvd: only 24 specics arc sharcd bctwccn the
two studies. The obscrvcJ dillcrcnccs can be attributcd to di!Tercnccs in
sampling stratcgy and gcars: wc samplcd 2 muddy. intcrtidal channcls
with a bcam trawl net, whilc LITTLE et al. ( 1988) usee! a beach seine ovcr
sandy substrata.
Leaving out the invcrtebrate component, it is evident that the fish
community or Tudor <.:rcck is a typical, tropical shallow-water community where few spccics constitutc the bulk of the catch (> 70%)
456
198
WAKWABI & MEES
2
sample scores
802.
.,
812
A12 •
1
•A01
SHORT RAINS
0
.Aas
801•
(1)
803. •
A04
805 • • AO?
DRYSEASON7
(2)
(2)
(1)
0
1
2
(a)
Fig. 3. R.:std!s of the corrcspondanc.: analysis (CA) with the oruination plots for (a) sampic ~cores and (hl spccks :;cores; dcpicting the tlm.:c scasonal cpibcnthk L'otnrnutli!ics on
Tu dm ctn·k. f\'hltnll;tsa. 1\L'Il)';\, du ring !hl' be am trawl study (May 1'!'!5 through April
1'.l9o). Na mes of months. ti de mun ber. and spcci..:s and !axa ahhrcviatcd as in Fig. 3 <llld
Table 2.
clc:;pitc the large numhcr of spccics (QtJINN. 19R0). lndccd. only six
!ish spccies ( Yongc:iclztlrys nebulosus, Plorosus linearus, Lu~janus .fitlvi-
.flumma, Acropoma japonicum, Cet-res oyena, and 5'aurida undosqumnis)
togdlwr CDnstitutcd ovcr 70C'/o of the total tish catch. Most of the reportee! spccics (61 spccies = 85%) were each less than 1% of the total
catch.
The multivariate statistical techniques cmploycd on the catch data for
the bcam trawl study in the backwatcrs of Tudor crcck idcntifled threc
457
199
EPI BENTHOS TUDOR CREEK, MOMBASA. KENYA
1
e
Spra deli
species scores
N
Ul
·xro
e
0.5
-
e
Leio equu
Plolline
•
Aero japo
Hemi far
Pen a se mi
e
•
e
Mono argc
Cepha
e
•
Yang nebu
0
Sphy jell
Olig keie
e
e
e Stol spec
e
Pena mono•
e Lutj fulv
Saur undo
•
ecari
e
Gerr oyen
axis 1
8oth mane
Meta mono
e
Pena indi
•
e Gobi spec
(0.5) -
eApog late
( 1)
(1)
1
1
1
(0.5)
0
0.5
1
(b)
Fig. 3.
(Continuccl).
communitics of the cpibcnthos ticd to the rainfall pattern. The short
rainy sl.'ason h;ld nwrl.' spccics wllilc the long rainy sc;1son had the
ic:tSt divcrsity. ln !ClïllS of numbers. the thrl'L' L'OilllllllllÎtÎL'S had very
strong dL)!11inath.:l.' of t'cw spc-.:ies cont'orming to the general observation
that trnpical l'sluarinc nr ~.·oastal ecosystems tend to he very diverse
but with very low cknsities for the majority of species (QUINN, 19HO).
The rcstrictcd size ranges for ali imlividuals caught during this study
may be largcly duc to two processcs: sclcctivity of the gcar and/or
dynamic replacement of the populations through seasonal rccruitment,
fast sizt: progression and emigration. Only juvenile stages of most (in
fact ali) specics wcre caught. The dill'ercnl species probably occupy
thesc waters for a very limited period to fced and/or ln escape from
458
200
WAKWAB! & MEES
·- - - - -- - - - - - - - - -- - - -- - - - - - -·-
..----------------------1"
- ·-
· - --·- · -
(- wct
- ---
------· --
- - - - · --
•
short ra ins
::a dry
Aero japo Cari mix Gobi spec Yong nebu Leio equu Mono arge Pena indi Pena semi Saur undo Squid mix
Apog la tc Gcrr oyen Olig keie Hemir far Lvti fulv Meta mon pena mono P1ot fine
Sphy jell
SPECIES
-- - - - - - - - - - - - - - - - - - - · - -- - - - - -- -----------Fig. -+. Scasonul (long ruiny scason, short ruiny scason und dry season) cpibcnthic
communitics of Tudor crcck including only spccics with an average catch of > 3
individuals in the montilly tows (total 120m 2) of the bcam trawl study (May 1995 through
April 1996). Names or spccies and taxa as in Fig. 2.
predation. For the penaeid component of the epibcnthos, the backwatcrs
arc an important nursery for their ncwly settling postlarvae and juvenile
stages (WAKWAI31, 1988, 1996, WAKWABI & .lACCARINI, 1993). Most
abundant juvenile fishes are second and third consumer spccics (LITTLE
et al., 1988), confirming the fceding and protection rolcs of this arca.
Though the emerging community structure is bascd on the rainfall pattern,
rains per sc arc not ncccssarily the causative factor. They probably
determine the rcsull<lnt food and prolcctive conditions in thesc waters.
which arc perhaps the most important and ovcrriding rcquiremcnts of
the juvenile stages of the lish and crustaccan populations cncountercd
hen.::.
ACKNOWLEDGEMENTS
This paper is bascd on the data collcctcd with the support from WIOMSA
MARG 1 rcscarch grant (contract No. 298010.5). The authors arc indebtcd
to Dr Okemwa, D[rcctor of KMFRl for allowing the use of facilities and
staff at the KMFRI Mombasa Centre. Special thanks to Mr Boaz Orembo
of KMFRI Mombasa, Kenya and to Misi'i Ann Dcwickc, RUG, Marine
Biology section, Bclgium for the teehnical support and advicc during the
study.
459
EPIBENTHOS TUDOR CREEK. MOMB:-\SA. KENYA
201
REFERENCES
BIANCHI, G., 1985. FAO species identification shccts for lishcry purposes. Field guide
on the conlmcrcial lllarine and bmckishwoter specics r!f7illlzanio. FAO-UN, Rome.
BLABER, S ..LM., O.T. BREWER, J.P. SALIN!, L.O. KERR & C. CORNi\CHER, 1992.
Species composition and biomass of lishcs in Tropical seagrasses at Groote Eylandi,
Northcrn Australia. East Coast. Shell' Sc. 35 (6): 605-620.
CYRUS, D.P. & A.T. FORBES, 1996. Prcliminary results on the role or KwaZulu-Natal
harbours as nursery grounds t'or juveniles of selectecl mari ne organisms which ut il ise
estuarics. S. Afri. J. Wildl. Res. 26 ( 1-3): 67-R l.
01.0 TROCH.l'vl., J. !\1EES, l. PAPADOPOULOS & E.O. Wi\KWi\lll, 1996. Fish eommunitics in a Tropical bay (Gazi Bay, Kenya): seagrass bcds vs. unvegetated areas. Neth.
J. Zoo!. 46 (3-4): 236-252.
FISHER. W. & G. BlANCHI, 19R4. Fl\0 species identification sheets.filrfishcrv flliiJ)(Ises:
IV<'stern lndiun Occan.fishing arca 51. FAO-UN. Rome.
FOl'DA. M.M. & !VI. AL-MLHIARR:\MI, 1995. An initial assessment or mangrove
rcs ourccs and human activities at Maboul Island, Arabian sca. Oman. Hyclrobiologia
295 (1-3): :15:1-362.
GILl.ANDERS. B.i'vl .. 1997. Pallerns or abunclance and siz..: structure in the blue gropcr.
Aclwcmdus viridis (Pisœs, Labridac): Evidence of links betwccn cstuarics and
coastal rccf's. Environ. Biol. Fish. 49 (2): 153-173.
HARRIS, S.A. & D. P. CYRUS, 1996. Larval and juvenile lishes in the surf zone adjacent
ro the St. Lucia Estuary mouth , KwaZulu-Natal. South Africa. Mar. Frcshwat. Res.
47 (2): 465-482.
HERKE. W. I-l .. 1995. Natural lishcrics. marsh management. and mariculture: complexity
and conrlict in Lousiana. Estuarics 18 ( 1A): 10-17.
HILL, !\1.0., 197:1. Divcrsity and cvenncss: a unil'ying notation and ils consequences.
Eco!. 54: 427-432.
HUSSAIN, S.M. & M. SAI\·1AD, 1995. Somc physico-chcmieal paramctcrs ofbackwatcrs
of sandspit (northern Arabi an sca, Pakistan coast). Pakistan J. Zoo! 27 (2): 191-194.
KI~lA:'\1. E.N .. G.K. MWATI-IA, E.O. WAKWA!ll & .J.M. NTII3A, 1')96. f<ishcrs of a
shallow Tropic·al cslll~lry. Gazi Kenya. Mar. Freshwal. R..:s. 47: X57-86X.
K!'EIIl. R.T. & M.K. KNO\\'I.TON, I9<J5. Stage-structurcd interactions bctwccn s..:asonal
and permanent n:sidcnts or an estuarinc nckton comlnunity. OeL·ologi;l (l3crlin) IOJ
(4): 425-4:14.
L:\EGDSGt\i\IW, P. & C.R . .IOIINSON. 19')5. Mangrove. habitats as nurseries: Unique
ass embl~1gcs of juw.nile lish in subtropical mangroves in c;Jslcrn 1\uslralia. Mar.
Eco!. Progr. Scr. 126 (1-3): 67-81.
LITTLE. i\'l.C .. P.J. RL\ Y & S .J. G ROVE, 198~. The lish communily <>fan East African
mangrove Cl'eck. J. Fish Biol. 32: 729-747.
Î\J..\1\GtiLL.IER, S .. G. VAN DER VELDE. F. DEIIAIRS, M.A. HEMMING/\ & S. RA.It\(illi'.-\L. 1997. Trophic relatiunships in a11 illlc:l'linkcd mangrove - scag1·ass ecusystem as traccd by clclta-13C and delta-15N. Ma1·. Eco!. Progr. Ser. 151 (1-3): 115-121.
Monm. H., 1981. Studics on the fishcries biology of the gianl tiger pr~1wn l'enuc/1.\
lilOilodon in the Philippines. SEAFDEC Aquac. Tech. Rcp. 7: 12R p.
N ORCONSULT, A .S., 1975. Mombasa watcr pollution and wastc disposai study. Morille
flll'l'.l'tigotions, voL IV. chapt 5.
D.A. & J.C. HANNAN. l'J94.
Th~~ c~.:ologi~.:al eiTc~.:ts oi' ,structur;d llood
mitigation ll·orks 011 fish huhilats and lish ~onHnunities in the lower Clarence Rivc1·
systcln nf south-cast Australia. Estuaries 17 (2): 427-461 .
POI.I.i\RD.
460
202
\VAKWABI & MEES
QUJi\:-<, N.J., 19RO. Analysis of temporal changes in fish assemblages in Serpentine creek,
Queensland. Env ir. Biol. Fish. 5: 117- J:lJ.
SEDilERRY. G.R. & J. CARTER, 1993. The fish COilllllUnity or:\ sh;illow tropica l l;lgnon
in Belize, Central America. Estuaries 16 (2): Jl)X-215.
SCI-I:VliTTER-Suro, J.J. & H.C. GAMUOA-PEREZ, 1995. Composition and distribution
of continental fishes in southern Quintina Roo, Yueatan Peninsular Mexico. Revisl.
Biol. Trop. 44 (1): 199-212.
S;vtJTII. IV!. M. & P.C. l-IEEMSTRA, 1986. Smith'.1· seafishc.\. Springer-Verlag, London.
WAK \l'Alli, E.O., 1996. Rccruitment of the giant (Jumbo) ti ger prawn l'cno<'ll.l' nwnodon
in the baekwaters of Tudor creek, Mombasa Kenya. Netwrl suh111i11cd lo W/OMS!I
for rcscarch 1\·ork carricd 0111 wu/er MARC 1 rescorch gran/ (non/mel 11° sc.
2W\0!0.5). 35 p.
WAK\I'Aill, E.O .. I')XX. The population dynamics and the fishery of penacid prawns in
Tudor neck, Mombasa with spcci:li cmphasis on Pcnoc•us nwnmlon. foahric. 17lJ8.
Mastcr ,,(Science lhesis, Uni,•crsil\' of'Naimhi Ken ya. 235 p.
\\',\K\1'.-\llt. E.O. & Y. JAC'Ci\RIN I. 1993. The distribution and <lhunclancc or pl anktonic
pcnacid larvae in Tuh<lr erce k. Mombasa Kenya. Hydrobiologia 264: 1X5-IIJ2 .
WHIT FIEI.D. A.K .. 1997. Fish conservation in south AJ'rican cstuarics. Aqual. Conserv. 7
( 1): 1- 1 1.
WHITFIELD. A. K. & !-J.I'v1. KOK. 1992. Rccruitmcn\ of juvenile marine fishes into
pcmwncntly open and ~casonally open cstuarinc systems on the soulhem coast of
South At'rica. lchthyol. Bull. J. L.B. Smith lnsl. lchthyol. 57: 1-JlJ.
WJLLI.·\,\\SON, 1., C. KING & P. B. M.YiïiER. 1994. A cnmparison of lish COilllllllnities
in unmodilied und modilicd insh<m: habitat~ of Raby Bay. Queensland. Est. Coast.
Shclï Si:. J9 \4): 401-411.
APPENDIX
----------·----·-----~~~x 95 _:!_Ll_~l_2_~__:!~~5 t~tg 95 ~1)_']'_~5 Oc:t ~')__['iov lJ5 Lkc _2~.:!~~-96 h:~
AcTopomatidac
A cror>i>llla juponit·wn
<J
Am.:nmriidac
t1mcwwrius hisf>mlus
Apüg(lnidac:·'
Apngrm latemlis
20
Apogon HigriJ'CS
Apogon sal'(Jyensis
Apogun sp
3
Fmderia au rita
Atherinidat:*
Adu:rùzomorus dum lccilnalis
Bdonidae•
1.'do:HlntS ([Cll.l'
Blen"iid:J.e*
Pctrosârtes sp
llnthi.dac"
Botlllt.l mancus
Psewlorhom/ms arsirrs
4
26
7
5
:no
29
<)
l'v1a~-~- 0~~Y<':_}(!~!__?~·
15
22
400
()
2
0
to
()J
1
7.
-J
JO
0
0
15
0
rn
v
2
<)
5
_-·,
4
2
6
10
2
3
2
2
1
4
1
2
3
4
2
6
2
Il
1
n o
14
8
0
rn
:r:
C/)
-J
c
0
0
:;v
7 0
3
4
4
0
n
:;v
(11
(11
A
7
3
7
5
2
2
2
10
7
5
07
2
2
21
0
2
9
43
3
1
()
:v
C/)
2
5
0
m
67
112
2
2
0
2
0
""'
to
3
C.Jran:gidac''
Cc<rant ignobilis*
Clupeidac'
SJ•rmdfoù/cs delit·mulrrs
Pu rat>lagmia !Jilineaw*
44
<)(i
3
>
A
2
1
4
Je\
2
z
-<
:v
Dxt;. lopkriclac
Dacl>IopTi·lw oriellfolis
Engmulidac*
!0
0
'..N
""'.......
0\
----------~-----------jv1~__9_:'i_~~0J5 Jul_~5 Au~-2~~ St:_ll__é)_:'i_ ~c:_t__Y__:'i__,~~5 !)cc 95 J~n 9~- Feb 96 Mar 96 -~p~~(> Total <;;
1
Srohphorus indictl.\*
2
()
1
_1
Stof<ï'horus sp
1
31
1
10
43
Ephippudae*
1-'l<lliH o!Jicularis
2
1
3
0
Gcrreidac'
,
_1
Cerre.; _{ilcm~enrust/S*
()
7
10
Cerre.1 o n•na•
24
17
20
6
9
1
7
2
100
84
34
5
309
5
Gcrn··J ~p
1
1
0
Gobiidac *
ilcellirugol>ius audax
Amhlygobitts albiuwcttlattts
c,:1prr~·cnrms ocrujàciarus
Cnatlwlepis sp
Cubitt.1 sp
Ofigo!epis keiensis
24
0.1.:rurichrhn· opltrfwlii!OIIC/1/a
}(mge ichthn nclmlosus
29
Huem ul id ac*
Pfectr,rhYncltus gaterÎiitt
Pcmuufa.l)> o iil·accu/!1
7
1
2
_,
1
12
6
7
21
25
~
8
·'
19
6S
21
40
12
12
4
65
2
9
4
7
15
20
3
5
9
1
6
2
192
73
106
136
2
7
23
2
3
48
152
4
745
0
0
0
0
1
2
0
12
1
4
1
·'
2
2
3
1
8
16
8
0
0
:!
11
-'
27
1
9
27
3
1
5
13
65
0
65
2
1
0
6
2
0
0
Lei og.tmth idac*
Le iog11mlws equulct
Lciognmhu.> bindu
Le thrinidae*
Lerltrùws hamk*
Le1hrùws sp
Lutj anidae*
1
+-
<
>
7-
~
~
;<o
::;::
rn
(Tj
Hemiramphidae"'
Z!'nmdwprerus clispar '
llemirlta111phus jiu-*
10
0
5
2
12
4
1)
2
-'-
2
3
2
cr.
.j::>.
1
0'1
tv
May 95 Jun 95 Jul 95 Aug 95 Sep _~-_5.~cl 95 Nov 95 Dcc 95 Jan 96 Fcb 96 Mar l)6 Apr l)(, Total 'ln
LutjtiiiiiS argemimm:ufal
1
2 0
1
""~'
42
95
151
89
9
)en
9
Lutiw11u ficll'ijlammo'
2
5
72
27
22
~"'~
1 ()
Lutjanus chrcnbCJgii
1
2
LwjaIl liS sr
3 0
Lutjanus julvu.1
1 0
Monodactylidae
!vlonodactdus cugentcus
41
4
2
74
3
2
6
7
8
Mogilidae*
'Valemugil .mheli
3
15
2
21 0
Mullidae*
Upeneus tragulu*
2
6 0
3
4
Upencus l'irtarus
5 0
Ostraciidae•
UJcloria comuw*
2
2 0
Lactoriafomasini
2 0
Platycephalidac*
-,
Cociclla crocodila*
2
2
9 0
Papillowliceps longicep.1*
5
6 0
Plalycephalus sp
2
li 0
3
3
3
Percorphidac
Ben1brops platyrhmchus
0
Plotosidae*
Pfotosus lineatus*
167
14
77
49
226
15
2
552 9
Pornacentridae*
Chrysoptera annulata
1 0
Plectrogl_,phidodon lacn·
li
3
16 0
Scorpaenidae*
7
Derulrochi ms brach_vpte rus
2
12 0
8
Parascorpar1w mossambica*
1 0
Svnanceia l'errucosa
0
rn
"'0
CJ:l
rn
z
...:j
::r:
0
Vl
.....,
c
0
0
;;v
(')
;;v
rn
rn
A
~
0
~
CJ:l
>
Vl
>
A
rn
z
;;;:
t<>
0
Vl
.j::..
0\
(.;.)
- ---· - - ------- ------- --- -----
--~-~~----- _!.J~ty Sl5_~~-~5 -~ul 9~__:'_~~E l)5 Sep l)5 _2':!_~5 -~~\'_2_5 Dl'c 95 _Jan 9Q_ ~'.:_b 96__ ~~~ 2~_p_I:_~Y<i Tu~~~
Scrranidac
(1
Ccplwlof'lwlis orgtts
0
Lj>incJ>helm I!WI'ill!l
Siganidae*
Siganus cunaliculatus
Sillaginidae''
Sillago si hama*
Sphyrianidae'
Sphymcna je/lu*
Syngnathidae"
Syngnarhus acus
3
Syngnathus biaculcutus"
Smgnarhus sp
Synodontidae*
Saurida undosquo111is
32
Teraponiclac*
Ti'raponja r/nut
Tetraodontidae*
Arothmn im11wculatus
Arorhmn nigripuncrmus
Canthigaster solandri
Caridca
21 ~
Penaeidae
Metapenaeus 1!/0IIOccms 128
Pmacus indims
14
Penaeus monodon
Penaeus semisulcmus
65
Stomatopoda
3
Cephalopoda
Total
!\'umber of specics
t.J
0
G
628
28
7
2
3
10
7
54
13
3)
46
22
2
2
Il
0
3
0
1~2
3
14
0
0
2
2
22
15
40
~
7:
:;:::
j::
5
24
2
64
43
16
30
21
3
3
26
119
9
1R
135
14
54
2
508
28
ll
9
10
107
2
13-'1
24
727
11
4
4
297
23
5
4
61
4
103
lü
)0
89
5
4
25
29
61
4
33
--'
41
9
135
)0
~9
-'
292
21
1
12
14
7
24
124
18
5-'10
32
954
33
613
500
41
-'
6
1
625
21
2
0
65
19
33
5
6
23
13
0
0
513
29
--'
3
7
7
8
Il
l
9
4
0
0
8
]l
l)
277
7
0
81
222
6396
620
989
583
31
27
22 _
_____:_33_____________
-'~
0-
cc
!<'
:s::
rn
CTJ
v~
.j::..
~