food web of benthic macroinvertebrates in a large yangtze
TRANSCRIPT
Fundamental and Appl~ed Llmnology Archlv fur Hydroblolog~e Vol 171/4. "1 { O ' a Ma} 'O(18
, ) - L / P I ! < ~ C ; S ~ I I t-t, ~ I ~ ~ ~ V ~ I ~ "008
Food web of benthic macroinvertebrates in a large Yangtze River-connected lake: the role of flood disturbance
Xue-Qin Liu and Hong-Zhu Wang*
: + ~ o Y e c Laboratorv ~f Freshwater Ecology and B~otechnology, lnst~tute of Hydrob~ology, Ch~nese - -x le ] i? \ , I ; ! Sac~enres Wuhan C h ~ n a
'>;i:n (3 fisijl+s i [able and 1 a p p e ~ l d ~ x
Abstract: i ill, ~III(I! \\.I, c r ~ ~ ~ < l ~ ~ i I i . i l ill I.al,L, I)IIII;IIII~~~LI. ;I I ; I I~L ' ~ ~ i \ c ~ - c o i ~ ~ i c ~ ~ i c i l I;II\L' 011 the Ynli:lt/c Rl\,cl- Ilooci-
III.~>:III;C 111; 1 1 1 ~ . I > ~ ' ~ i ~ l i i ~ , l i~o( l \ \e l1 1 1 1 ;I I ~ ~ \ ~ I ~ - c ~ I I ~ I ~ L ~ . I ~ I I l;~I\c, 1\1;1c1~11i1i\~c1.tchr:~!e~ ill ~ l i c I;rI\e k c l
.. . 1 : , ,~ I :L - I i i~. ; ! h i III~~IIII\L.\ ;1\ ~llc, i lo~ii i~l;~l i l ~ I - O L I I ) . Ill\\ COIIIICC(;III:C. Iiigli Ie\cl ~I'OI~III~VOI-~. based o n ilctr-i(us
. . . ; . ! . ! : : . : i : ~ ~ I . ~ : ~ ~ I I L ~ I I I I I ~ ,111:l III!I\I ~ I I ~ L ' \ I I ~ I I L.OI~L,~,I~I~.II~II; 011 ;I Ic\\ 111 i1 \ \ . 0111 ;111;1l!.\c\ \ho\\ecI tliilt Hoocl ilislur- , ..,. I < . ~ . I .. ::: I ? i i : g 1 ! - ! . 1 1 1 1 I . I~IOI al'l~.i1111; 111~. I>~,llll l i~. Ioo;I \\ch ill [.;II\~ L ) I I I ~ ~ ~ I I I ~ ~ I L I . '1'11~ I ~ L I I ~ ~ ~ c ' I ~ \ I > ~ ' L ; I ~ ~ c ~ ~ c \ ;111c1 ~LI I IC-
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introduction i ~ i g cf'ii'c~s \;II'! \uhstan~ially :~cc.or-dins to locatio~l \ \ i l I r i~ l ;I ~. i \ .e~. i~ic ~ictwork. i,e. ~ l i e y act :IS da~ii:rpi~ly I'o~-cc\ i l l uplalltl st~-c:r~rl\ hul as 1.cplenishing forces in lo \ \ . l a~~d I l o o c l p l ~ ~ ~ n (Lake et al. 2006). Although ;I lalye ~ l l ~ ~ i l h t ' ~ . 01' \ t ~ ~ d i c \ cleal will1 the et't'ec~.; ol' Hoocls. nlo\L re ~011cc11lr;lte~I OII S~~~:IIIIS and ri\.crs. A rela- ~i\.c.ly s~val l 11~11iihel- 01' . ;~~~cl ies li:~ve cxaminccl riveri~ic' \\ctlancls s ~ ~ c l i :I\ ~. i \c~--c~t inec l t 'd lakes o n HooJl?lain\ ( Kirly\l'o~-d el ul. 2001). However. species riclinc\s ant1 ;tbuncla~l~.e ;we o l ' t r~ l Iiighel- in Ilooclpl;ri~ls ttiall i l l ~.i\,el. ~. I ia~lnt?l \ I M'arJ 4.1 :II. 199'9). Hence. co~lsiclcri~ly SIIL'-
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I>iotll\ersit!~ censer\ atioll. i l is nect.xary to ~trldc~-- \t;tlrcl Iiou Iloud d i s t~ l rha r~ce al'fecr the conlrn~lrlitics 1 1 ; !.I\ c ~ ~ - c o ~ ~ ~ i ~ ~ ~ t c c l \ \~~~t l ;~n( l s ,
\lac.roinvc~-teb~-ate\ arc irnporral~l ~ I - O L I ~ S 01' bcr1- 1111, c .onl~l l~i~~i t ic \ 111 thc ri\.cr.inc net\vorh. They LII-c I I I O I . ~ \~111icri1bIe (0 bccl 111o~c11icrit c l ~ ~ r i ~ i p lloodir~g i l l ~ ~ n I ~ O S C ~i lol>~lc ;t1li11iitl\ \t~cti a\ ti\li. 11~1ring flood- 1 1 1 ~ ~ . I I I L I ~ I . O ~ I I \ . ~ I . [ ~ ~ > I ;111: :tfl'ec-tccl by a colnhination
\r :II~:I- \.cloc.it!. ;t111l \ c o ~ ~ r i n g ( I - l o l o ~ i i ~ ~ ~ k i 'Yr Biggs .?0001 al~cl 135 111)!\i~.al bed nlo\,enlent of tlie stream I I c~ I . 7001 1. !\ li~ryc ~ L I I I I ~ C I . o l ' s t~~t l ie \ i i s i \ ~ . ~lct111 \I 1111 1 1 1 ~ c , I ' f c ~ ~ l \ 01. tloocl\ 0 1 1 ~ ~ ~ ; ~ ~ , r o i ~ i \ , e ~ - t c - 111 L ~ ~ ~ , k I L,.? S , I ~ ~ I I . 10x0. l?t~.ker & l i ~ ~ r ! ' ~ i 2006. SLII-en ,\ I ( ) \ \ L , [ [ 2oi I . ~ I I O \ ~ \lie\! 1119 11l:tt lloocl c l i \ ~ t ~ r b i ~ ~ ~ e e s I L . W I I I 111 t t I . L Y ~ L I L , I I ~ ) I I ( I ! \pccic\ r i c I i n ~ ~ ~ \ ; I I I C I :11~~11~cIa1icc. iw! illa~ ~.c.c.o\ '.I.\ \ \ a \ ~-al?icl (c.r. I.ahc 2000. C;.jcrlo\ ct .ti .'OO.: i J IIII .C(.I\ c.1-. llic! i~ l \o \ l l o \ \ c ~ ~ l <I b l ~ i t ' t 111 C O I I I
I I ~ I I I I ~ I ! c.orlll>c)\llroll to O I I C i lo~~lini~lctl h! opl)orltilli>- !I,. l ; I \ : l l o l ~ ~ l ~ ; l l 1 l 01 llll\t~ll~lc c~otl~lilioll\ (C.2. l-o\t l l h ~ l l ~ l
. . : . l i I007 I. OIIIL\I. \ ~ t ~ c I i ~ \ I I I ~ ~ L Y I I L > t l ~ i t t flood\ L ~ O L I I C I <!~I , . I I I ~ ~ c I ~ c c ~ I ~ ~ ~ . I I ~ ~ L ~ I ~ ~ I L . ~ I O I I \ \ I I C I I ; I \ ~ ~ o ~ ~ ~ p c t i [ i o ~ l L I I I C I ! . . ! : ~ I : I ~ ~ O I I I I ' ~ I O I I I \ O I ~ 2002). I i o \ \ ~ ~ ~ r . o~il! it s~ii i~ll ! ~ I I I I ! ~ L . I - r ~ l ' \ I I I L ~ I C \ ;~c.tt~all!, clcal \\ 1111 [ I I C ~ I ~ I I L I ~ I I C C ~ 01' I I . \ O ( I \ oil I ~ c ~ ~ r ~ l l i i . \ \ ~ . h \ . I t h:~s 1 ~ ~ ~ c . n Io11,c hnown that i ~1 \$ c.!h ;I I .L , 11111)01.1:11il 111 I I I ~ ( I c ' ~ \ ~ ; ~ I ~ c ~ ~ I I ~ 11o~\ > 01' 111~1- 1 I I I in cc.o\y\tCln\ r l l ~ u - ~ l IC)21. Odum ! i .S~LICI IL . \ ,111 ~ I I L . c ~ l ' l ~ ~ c ~ t \ 01' l l ooc l \ C I I I I I I ; I L , I . ~ ~ I I \ , ~ I . -
~ebrate I'ootl \vcbs ~niglit provide useful information fol. eco5ysrcm rniuiagement ot' floodplain ecosystems.
As one of the la-gcst tloodplains in the world. the X~nytye River iloodplain is characteri7ed by many xhallow lakes interlac,ing with the river network. From the 1950s t t ) 1970s. most I:tkes were isolated from the rltain c l i~~nncl by cl:llrls arid leveex. and only three cur- rently retain n ~ t t ~ ~ r a l connection with the river. The tlextruction of' hydrological conr~ectivity between the river and lakes resultecl in a loss of habitat hete~.ope- neity ancl species biodivessi~y, as well as other envi- ronmental problems such as lake eu~r-ophic~ttion (Cai & Z ~ O L I 1096. W ~ n g et al. 1005). When considering res~orntio~l of the Yangtze floodplain. i t is impol.tnnt lo have u n undersl;t~~ding of the floodplain ecosystem. Hou.c\ el-. lnost s t ~ ~ d i e s have concentrated on lakes that li:~cl bccll i\ol;tted h-om the Yangtze River (e.g. Liang Xr L , ~ I I I%)<. I,i Xr ('ui 7005) , while little has been done 011 \r'augt/c lii\er-connectetl lakes.
.fIiis study t'ocusex o n research conductetl on a Iiu-gr Yallgt/t. IZi~el--connected lake. Lahe Dongtingh~~. in tlie mldtlle ~citclies of (he Yangt/.e River. 0u1-goal ia I O clctcr~ninc tropt~ic I-elationships among benthic niac- ~.oinvcrtct.~.ates ant1 the el'fects ot'llood distul~bance on
Fig. 1 . S;~rnplirt: silca or) Luhc I)ongtingI~~l. Hu- win . Chin;(. Sllacled :~rcu\ al-t \ea\orlally Iloo~letl en\. Arl-uwh hhou' lllr clil.cclion of watcl- Ilou.
Ber i t h i c mac ro~nve r teb ra tes In a river connec ted lake 299 - -- - - -- - - --
Material and methods
Study site
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Sampling and dietary analysis
Anirnalb \\ere collecicd along a 500 111 trance1 o n eac.h OCL.,I-
\ ion. Hen:llic m;~croir~\cl.tchraLe\ were ;~ l sc ) c o l l ~ ~ t r ~ c l b! tiarlcl in sh:~llou. near \horc \ \ :~ lcr \ . Zcbr;~ innaaels attachcd on h;~i t l \11h\tra1;1 .vcrc c~ol le~~lc. t l by 11~1. 111 IoM'-IIoM regioii\ wit11 :I~~LI;II-
ii' p1:111t\. / i ~ i ~ b e ~ i ~ l i o \ \vcrc. ~~ol lcctecl hy a hancl net. M:icroii~- \e~-tebr:~tc \1wci1ile11\ ~ c r e :II~I) collccteil t ' ro~i i l ~ \ l i i n g t r i ~ \ \ l \ . Sample\ .*ere taken l o the l aho~ l to ry and prcser\.ccl ill 10 ' z
Formalin l ~ - i o ~ . to \ortill?. A l l spccimena were itlen~iticcl lo .;ptS- cics Ic~ \c l when ~)o\ \ ih le. based on rhc key., i l l Spcrhel- ( 104Si. 1,111 cL ;\I. . 1979). Vlor\c et '11. ( 1994) ;11id tiplel- (2001 ) . ! l ~ i i ~ i i : ~ l \ In ( l ~ ~ i ~ ~ l t i ~ : ~ t i \ c \;1111pl'\ uerc i ' o ~ ~ r ~ l c d and weighed. I 'hc \ \ct \ \ r ~ g h t m,l\a \\as \ ~ ~ l ) \ e ~ l l ~ c n t l y tr;inblcrred to i lry weight m:la\ u\ ing :I clry/wc~ r:~tic~ tYwi R I.i;~ng IL)9C)). li.mpor;~I ellanye.\ in i len\i l> and 1>111n1a\\ ol 'niaei~oin\rrtcbr:~~e\ ucrc ;~\\eh\ctl I)! one-U:I I N O V A .
l'en i,itli\ icluala I l um c~1i.h apccieh i'roill cacti nlonth \\ere lahen rant lo~nly I'or ~ L I I c.ontenl anal)aia. Il'tlicrr. \\ere lea\ th;111 I 0 \peci~ncn\. :III \\.cue ~ ~ \ e d . \+'oodu;u.cl KL Hilclrc\v t 300 1 )
I ' o~~n t l th::~ largc. number\ 01' i~idi\iclu:il y t s I> 100) ill.r' 11ec- L.\\:IU t ~ ) detect :III trol>Iiic link.;. Ilowcver. \uch ;III el'l'ort &:I\
not i'c;i\il)lc c\l~cc.i;~l l \ in the large l':uigt/.c Ki\cr-ct~nncctccl I;rkc J I I~ 11) l og i \~ i c ireason\. Moreover. tcn guta wcrc ~ i \ e t l c.om- monly in Food \ \eh \tutlic\ :uld cont i rmc~l to be c n o ~ i ~ l l 101- IIIO\I
i111c10i11\ c tch111e c . 1 : r \ - r c 1 1 ; 1 r ' will i : l l l l \ 1000. Thornpxc~l R To\\n\erlel 200.3. L i u ct al. 2006) .
Stom:~ch\ ;ulcl I 'ores~~r\ oI'animal\ bere rcmo\ci l arid pla~,ccl o n aliclc\ :uicl ;ill I'ootl conrcnt\ were \crape11 or bcl~~e~s/ccl o ~ i t undel. a cii\.;ccliny r~ricro.;cope. Food conten(\ 111' biv:~l\ c.\ u C r c I-c~novecl from \tomac~h\ u\ ing a pipette. Ver) alllall \\orliia ucr-c ~no~in tcc l \\I lolc. S~ornach ;~ncl gut c.ontents ~vc rc p~ -~~cc \ac t l ant1 ci:ui i i~lctl accoriling to ~ l l c t h o c l in L.iu et 31. (2000) alltl I.iu R M';III~ (2007). I-ood i'olltenra were \ L a i d \ v ~ t l i I.ugol'\ i oc l i ~~c \olutiori ;111il IIIOLII~~CCI For ~ii ic~roacopic determini~t io~i . L.aryc l'ood itcn~.; (>50 brln) here examined nnder IOOx m;~gnitic:~rion. .Algae ;lrrtl otlicr 5rn:ill i[cllrs ( < 5 O p m ) werc ex:rlninetl nnclcr 400x ~nagnil ication allel iclerltiticd 11) rhc loweal taxonomic Icvcl pc)\\ihle. :icce)rding to Ch i~ i c \ c Ailalysis ;Metliocl\ SLLIII- cl:rrd\ I t lunng ct :11. 1009~. ,411 focd itcmx \yere rnca\uri.d 11s- ing an r!cpicc~. I ~ ~ ~ L ~ I - O I I ~ C ~ C I - . :IIILI Lhcir voiuli1el1.i~ co l~ l r i hu~ ion \ uere3 CIIIII~LI~C~I \ \ p i 1 1 1 c ~ ~ l i ~ i i o ~ i I ' ~ r r n ~ ~ l a e . hy length ( L J - ~ o l u m c i V ) rel;~l~onsli i l)\ ce.g. log,,,\' = Iog,,,a + h log,,,L: ace %h:uig cYr
Huang 1991 I. 0 1 u\ i l lg meall \olurnes o f hod \l>cc.ie\ i r r rllc c. i~\ i l -onl~~err t .
Food web analysis
:\I1 colrrllion \pce.ies L\CI-C LIXCCI ill the l'oo~l wcb ;111:~1yxis wli i lc arc .;lic.:ic\ \\ere c.ccluclecl. Kirrc yecic.; inclucle~l one ol i - ~ ~ z h u c t r (Llr.i~iic.!~iiiiri .\oii.c,rh\i Hedd:u.dJ. five bivalve\ (,.I<.i/- /I(,O\/(I I l ~ i i i c i ~ \ i . \ (I,L,;I). C'~ii~(~o/~.si.s / ~ i . \ c ~ i ~ ~ i i / / ~ v (H~LILIC). /\'01,11-
l , i~/i i ici 1,!1iiici1.\1\ I .ILI et Zh;111g. Lci t i~/~ror i~/c i ,/i/~t.o,\li ( kle~iclc J.
. ~ i ~ / ~ ~ ~ r o ~ l . ~ ~ . s r i i ~ ~ \ ~/J~IIII.\II.\ Simpson) anel one oclonatc (t 'cir l~i ih~ \I).I. l ' l r c ~ \\ere t,\cluclcd d ~ l e to theil- lo\\. l'rcquencies o l 'o i ' c~~r - i.cncC in s:uiil>lc\ i< 5 i ). Suc~or ia l aninl:~ls (~iininl!, Ieechc\) \b~,l-c :(I\ ) c i c l ~ i c l ~ ~ ~ l I 'ro~ii t'ood weh ;111:1ly\i\ h e c a ~ ~ \ c LIieil- Iked- 111g liilh.. coultl liot be dcrcr~ii irrcd b> gut conten1 i~nal>hi \ . !\ \IIIUI~I~I i c 1>c1-ce1il:yc. \v;I\ 11\ec1 I~I q ~ ~ i ~ ~ i t i l ' j the c o i i t ~ - i h ~ ~ t i o ~ i of c;lc.ll l'oc el i tem l o the tot;~l gul colrtcnt\.
( ' (111 I~L,I~IIILY I'OOLI \( el?\ \\.ere ~ c ~ I I \ ~ I - L I L , ~ ~ L ~ io r e:1e11 \ : ~ ~ i ~ p l i ~ i g <lat~, iC'c,hc~~ L,I al. ILJ0O,. A suln11i;u-y ~ ~ c b u;~\ also ~.urnl>ilc.~l Ihai IIIC I I I I ~ ~ I LIII I.IIIIII~~OII specic\. FoocI \ \cb \t:~(i\t ic\ \ \ ~ I - cL
L.I!~~III;II~~LI 11, lOl1<1\\\: 1<11:il ~ i ~ i n i h e r 01' \ [ ~ ~ c i c \ ~S I . nu in be^- oi' / IN~I~L' I I~ \I-IL.I.IL.\ I.\ I. Lot;~l 11~111iher o f l i ~ i h \ I/.I. ~OI~IIC~L.~;IIIL~~
300 X . - 0 LILI and H.-Z. Wang
Results
Community structure of macroinvertebrates
The 3 1 cotnnion species of benthic macroinvertebrates i n L~ake Dongtinghu included one oligochnete, I8 mol- Iuhcs and 12 insccts (Appendix I ). The number of spe- cies uas rn~lch lowel- during the flood season (.July and Scplernher) than othcr periods. The density of zooben- thus in the lake W:IS 70.1 + 20.7 ind rn-' i ~ n c a n +- SE. the same belo\\)) and biomass was 13.3 2 3.5 g m ' (d ry maas) Molluscs were the rnost abundant group. compt-isiny 6 1.4 (2 (of the total density and 99.8 C?c ot' the bio~n;rs\. Generally. density and biomass of macro- in\,c~.lt.bra~c~s were much lower during the Aood seasnll Ilia11 othcr ~~cr iodl ; (Fig. 2 ) (ANOVA. p < 0.05).
Food composition of macroinvertebrates
In torat. 83') guts with food Srom 1 . 0 1 X dissected in- cli\.id~~all; were ~ ~ s c d I'or dietary analysis. The quantity 0 1 ' 2111 conttL[its scemed small in several species (e.g. ~ / l ~ / c ~ t ~ ) ~ < ( / . ~ t i ' ~ ~ / ; / i i ~ / ~ i ( , l . ( ~ O i ~ i / ) / l ~ ~ ~ l l l Sp. and c/:lpt/)f~/~;-
. , -- -. - . - .~ (10 +-
-. .. ..~ 7{
: ! I
, .
T-.
-. 8 + _ ~ ~ . . ~ 0 . -
S Fig. 2. Dcn\ity :~ni l Iiio nias\ (d ry weiglrt) (rncnn
( J~s~I -opoda +_ SE) 01' cornmorr inac- I L ~-oi~ive~-tch~.a~c froup5 i n
IT . ;i I.;lhc D O I I ~ I ~ I ~ ~ ~ U JLII.- r . . in: the sn~iipling 1x1-ioil
( May-No~cnlber. 2004). Different aymbols in- illcatc \ i p i h c a n l l y di1'-
( I f r rent ~ N > L I I I ~ al'ler- a .*.I> \,,,. \1.1! lu! 'i.p \ ( I ! . one-way INO OVA, slid il
Tuhcy post-lioc ~ c \ t .
Benth~c macrclnvertebrates In a river connected lake 301
I 1 . i i i I I I ~ C ~ I ~ I - ~ I ~ L C I I nern:~todc\. h~.yo/o:~n Iloatohlasts, ol iso~~liaetes. crus- -II~\. I:\ L-III! Ioori i ~ c n i \ \\'ere‘ 1o~111cI ill (lit' y t COIIICII~\ t;~cci~n\. ~ 1 1 ~ 1 . ~ i i i tcs. 111;1yIly nymphs. ul i irononiid la- .I :III \l jcc.~c\. i~iclucl ir iy inorg;~ni~. malerial. clt'lritu\. \,ac antl n ~ i s c c l l a ~ i c o ~ ~ ~ ~ i i : ~ t e r i ~ ~ l .
;.i .~~ioh;lc~tr~.ia (C'y;~riol>Iiyta). J i ; ~ ~ o ~ i i \ (Rac~iI la~.iopl iy I )c~ i~ i Icc l ill fornia~ion of food compo\it ion of l i lac- . I I c I i l ~ l i t i ~ . 0 1 1 1 I I 1 i i1 i i1 ~.oi~i\cl-tct-1r:ltes is yi\ ,cn in Appendix I . I n general. , ! ! i ~ o t l ; ~ ~ e I l : ~ t ~ ~ ~ ;~ncl c(~glc.noid\). ~i iacropliyte\. po l l rn mo\t zoohcnthos in Lake D o n g t i n g l i ~ ~ consumed a
S ! 4>11il.c1-\. !lI~t)lo/o;~ii\. li!,~I~.oicl\. k l : ~ t \ \ o ~ - ~ ~ i \ . rotiI'e~-s. wiclc r x ~ i y e o f l.oocl i tc~ni\. Detritus. ino~-ganic n i ~ ~ t c -
I 0 0 .~f~lor/oiita ~voodiana wootlirrtl~r
I f ,
I I I I I ('oi.hic.ulrr,fluri~inen
'A - :ill -
! (10
I t~~~noperna lacrrstri\ Cjnio douglasiae 411 -
Fig. 3. \ . c ~ ~ - ~ i t ~ i o ~ i \ 0 1 III:IIOI~ Io~)LI il~.111\ 0 1
~,;-IL\CIII;II!\C IIIO!ILI\~, \pc~.ii,, III L:II\C i j ' i~~lll i i~l~~ - L LILII~III~ 1 1 1 ~ \~;IIII]IIIO; I)CI.IOC~.
x ' 8 , ~ , ~ ! L ~ i :I~<;I, \IIo\\ JJI:I III [IIC lloott . .
, . ~ , ! -L!. \:\.:I.I/ :.I;I!:!-,>C,II~~\ ;II.L% !11i\\i11; . ,.,. . , ,. : : I l !~.,i:> !hltl,ll. \.\:.It L.OIIL~~LL~L!
.' . , ' : , . .
Table 1. I I I O I ! ,,\..I, - I . I I I , I I L . \ 1o1 1 1 1 ~ . I>L . I~ I~I IL I I I I I L I \ \ ~ . l > 0 1 I ;~hc I ) r l ~ l g ~ i ~ r g l ~ u c L I I - ~ I ~ ~ I I I C \;lllll~lillg pcsiod. The Ilood period i \ from i t 8 l \ I ~ I $ L , ~ I L , I I ~ I ~ ~ , I
I o t l t i ,\(,I ' , I ~ I I I \ I I L , , LI;I! l u l SL-p Nov SLII I I I I I ; I I .~
I : I I , I I I ~ I I I I I ~ I L ~ I ( 1 1 \ I > C L ' I C \ i \ i .?(I 2 14 3 3 5 l ' . L I I ~ I I > C . I , / I , O ~ L ~ I I I ~ I I \ . \ I ) ~ ' i l i ' \ I 5 8
1 > .. - I ' I I I 0 3 1
101;iI 1 1 1 1 1 1 1 1 ~ ~ ~ 1 1 ~ 1 I I I I ~ , 11.) , I 1 .~ : 1 1'7 I 0 8 150 203 ( l l ~ l ~ l ~ . c . ~ ~ ~ ~ ~ , . L . I ( . 1 I.\ I ! ) , I 2 0 (1.151 0 I S S 0. I46 0.1 13 I l l l l , ~ l ~ ~ ~ ~ l ~ l l \ l l \ I 1 1 . S ~ 4 : 4.4 J.5 4,s 5.7 I ~ I I I I I I L O I ! i 0 0.ii 0 . 0 2 001 0.74 0.6 I % ~ I I I I I I \ ! ) ~ c \ i / o t ~ l > c ~ ~ t I ~ o \ i
Functional feeding groups (FFGs)
This g r o ~ ~ p a l ~ o consu~ned a certain :uiiounl o f ;lni- ma1 m~~tc.rial. s ~ ~ c h ;IS rotifers. ICG primarily fed o n detritus (71.2 % ) . wilh a certain proportion of inor- ganic maict-i;~l. With regard to filterers. BC'F niainly cl.:trilus wicl prnlo/oans. and they ;~lso took a large ~Irnounl of cyariobactcria and rotifers. while ICF feel primarily on detritus (91.3 C ' c ) . In the die15 0 1 ' predatl)rs. rotifers were the chief' food item of AP. while mayfly nymphs (66.2 % ) and chirononiid larvae 113.7 9 ) made up almost all g ~ ~ t contents of LIP. With refercncc to temporal v~rri;rtion, food composition of I:I2Crs \.ariecl ill the sirnilal- way as that of tnost species. i.e. the\, illgcsred more algae and animal Inaterial dur- i l l ? ~ l i c lloodi~ig.
Food web of macroinvertebrate community
l'lic sulnlliar!. wch 0 1 ' Lahe Dongtinghu during rhc Sitmpling co~l~i~incel 5 l . ' s ~ ~ c i e s " (iticluding 3 1 zoo- benthos :NnJ 20 footl itc~iis) and 293 links. The link- age elc~i\iry u.24 5.7 anil thc directed conncctance was 0. I 1 .3 . High levels 01' o~nnivol-y were observed iri the hcnrhic c,om~iiunity. The ratio o f omnivores to zoo- hr~itlioS \,,a\ 0.6 I . l'liel-e wcrc changes in 1 1 1 0 ~ 1 I'oocl \\el> \rati,tic~\ dl~ring the san~pling pcriod (Tilhle 1 ). .Phe totill n~~rnl>c>~.S of "species" and links. and the 11~11iit~e1. 01'/oohe1itho\ \ \err much niallcr . while c o ~ i - r ic i~~;~r i i~c i111cl o~ i in i \o~-y were higher d u l - i ~ i ~ flooding ~l ian ill ot!icr pcrioel\.
.l'lic hcnthic. tooel u 'cb of Lahc Donglinghu w;~x h:~scd o ~ i d e t r i ~ ~ ~ \ . A~iiong the 30 food iteiiis. cIetrit~15 \\.;IS 1110~1 i~ii lx)rt ;~~it 1.01. niacroinvertehratc.. account- ing 1.01- 41 .i !/( ol'tlie tolal gut contents. A~iimal matc- ~-i;ll u l ~ o iontl-ihutcci u ci,r~:~in ~unount. i.c. protozoans. maytjy n \ ~iiphs and rotilkrs comprised I 1 . 1 %. 10.7 c) alicl 9.3 % 01' (lie l c ~ t ; ~ I respectively. 1norg;uiic mutel-i;~l ancl cy:~~iobactcri;i uteri. of some importance. compris- in2 0.7 (4- and 5 . j <'r ol' (he total. respecti~ely.
The rli\tribution of diffrl-ent kinds of links x a s ;tnalqzed ,:~secl o n thc volulnetric contribution of each link. K t . \~~ l t s sho\vecl that r i io~t l i n k accou~lted for a
Benthlc rnacro~l~vertebrates In a rlver connected lake 303 --
-- ~~ . *-- >, ,.- .. .-- -~ - - -
'\I .' I ! , ) -. , 1 0 1 2 ;
~ ~ - ' .~_ 1 1 10 1 1 2 0 0..3,) I ~ . ~ O ~ O . ~ ~ ~ 0 00 0 . ~ 0 0 X I 1 1,liIl - -- - - .. .,'
1 L\i*,l I \ L,l! \111;tIl ~ > l ~ ~ l ~ i O l ~ l i O l l 01. (0t;lI i l lgc\t iot l . 111 over - 5 ' r 0 1 IOI:II [ Ink\ . ~ h c \,oltrmetrii. contributioli \vas .!!:,<, III~III I 0 ' , . :\ I ~ I - g c ;IIIIOLIII~ of' i ~ i g c s t i o ~ i occ~~r rec l ! ] I <I b~ l l i i l l IILIIII~~L.I. of li11L\ (4 .6 ( 2 ) . 111cIicati11g t l ~a t I I ~ I O \ I CIICI.C\ . . I l o \ \ \ \\L*I-c L.o~i~.e~l t~. ; r te~l ill ;I lC'\\ tctecl- IIIL~ p ;~t l l \ \ . :~\ \ . A l o ~ ~ c o \ c ~ ~ . t l i i \ p :~ [ t c r~ i cl1:11iyecl l i ~ t l c ~ I ! l ~ O l l ~ l l l l l l lc il11(l \ ce l l l c~ l lIOt ( 0 tie ~ l t ' fectc~l l7y Il(>Oii l ! ~ \ ~ t ~ ~ . l i i ~ ~ l c c (b ig . 4 ) .
IIII~I':IL'~IOI~ \\.~.-h\ \$ere consrr.uctcd haw i l on rroph- , t : I I L ~ ~ L > o \ L.I-I:I~ ; I I I ~ O I ~ ~ 111:1~.roi1i\~c1~tehr:1tes. 111 I.;lke , . I ;. '!:!?! !II;IIIII. t 1 1 ~ . 1 . ~ \ \ ; I \ ~ i i oc I~ r ;~ te ~lictii1.b i)\:er1;1p
. : 1 : ! ! 1 1 i ~ ,IIIIIII,I!\ \ \ iil! ;I I ~ ~ C : I I ~ \,slur 01. Pi;rnk:~'s niche . % t~~ l L ~ l ) II~LIL.\ 0 1 0.40. Cie~ic~-;~ll!. dietill.! L ~ \ ~ I . I : I ~ I ' 1 1 11i;1< ~-oi lr \ ~. l~ i ' l l r ;~tes c l c ~ ~ ~ - c ; ~ \ c i l \ l iyhtlk CILII.~I~F
1111, \ ; I I ~ I~>~ I I I ;~ , 111~' IIIC;III \ ;~ lue ot'dictal.> o\c~-l;,p \vith- :,.11-11 /.I-(; \\:I\ 1111. Iiiyhest in I('(; i0.001. and the
i I I I ' I ( ! 2 1 . I)ictal.! o\.erl:~p \ \ a \ l n t ~ c l i h iyh- , t . I I I II>II~ ~ I -o I I ! )< 0 1 I>I.III~;I~> C O I I \ L I I ~ ~ C ~ \ th;ill ~ I I ~ ~ O I ~ F
, 1 1 Iic'i. < I O I I ~ ~ \ ' I l i e * l i iyllcxt o\.cI.~;II) c)ccu~.rcJ bet\\ etln ,1111.1 l( ' l . I I ) . ~ J ~ ! ~ \vIlile lhc l o \ \ c \ ~ w i ~ s ob\c~. i~c( l
~ L Y \ \ L ~ c ~ l I 11) LIINI OLII~>I. gI.(>Ll]3\ I l c \ \ tl1;111 0.02) . AI~IOI)~ ,:I i 1t111\ 0 1 ' Ill.llilal.! z:onhunlcl.\. clict:ll.y c1i cr l ;~p hctu.eeri !<( ' 1 , ;III(~ OIIIL*I. l.'17(-;\ 10.47- i ) .6~)) \i:~\ IOLLCI. th;111 those
> !!IOII? o t l i < ~ ~ ~ l,l'(;\ ((J.(>tl 0.05 1 . W i ~ h ~~ct 'c re~ icv to te111- .>OI.;II \ ;II-~;IIII!I)\. IIIC ~n;r~.r.oin\e~.tcbr:tte tood wel l ill the :i,~. c.ll:~tlgccl ~I-L*~III! ~ILI I . I I~~ tiltx \ : ~ ~ i i p l i ~ i y (F l y . 5 ) . 111
:.I rl!.. o i IILII~II~C.I-\ o l . \ l ~cc ie \ ;111d ITF( i \ . tlie \\el? \I~IIC-
. ;. \; .:< ~II!IL-II \ i l l~ l l i c ! - ( l ~ ~ r i l l g thc ilood ic;i\oll th;~ll ill , . , . . ! , : : ~ I I ! ! ! - ! !IL'I~.:Y; i , \ ~ ~ ' i ; l ! > \ \\ ~I~IIII I ~ I O \ ~ kFG\ :111(1
alnong FFGs \vcl.c much lower dur ing the flood wason than those i n other periods, w i l h the lowest obcrlap oc- currin: in . l u l y
Discussion
A common type o l ecosystem o n a floodplain. river- ~ .on t~ec tcd I i~hes hi~vt . PI-operties of both lot ic and Icntic watsrs. Our s t~ tdp is the first detaileel study or1 trophic rt,lationships o f benthic macroinvertebr~tes ill a Y;uigt~e Kivcl--connected lake. Former studies ol' ~n:~croin~,c.~-tebrnte foocl webs have shown that benthic webs ucr~.: hc;lvily based o n detritus i n a wide range 01' I'l.cshw;~ter ecoxy\tcms (Wal.ren 1989, Thompson Ji Touscnd 200-3. Id iu ct nl. 2006, Lit1 & Wany 2007). Al though detl.itus made the grealcsl contr ibution (;thout 40 0; ) 01' thc total ingestion i n the food u e h ol' I>ah-e D o n g t i n ~ h u . i t contributed rnuch less than those i n s t rc ; r~ i i~ (e.g. 'I';~v:~rcs-Cro~iiar & Wil l iams 19C)h)
a n d rivc~.-!sol;~tecl lakes (most > 80 (L') (e.g. L i u et al. 2000). A large amotlnt o f energy (abo~r t 30 (4 ) in thc k c i s c l e r i c I I r i k t o ~ i L I C ~ :13 cy;l~lob;~cte~.i;~. 1>1'otozo:uj\ ant1 roti l'ers.
h4any st~ld ics 011 I luv i ;~ l syxtcms sho\vecl th;lt b i - \a lvc coliec~or--1iltercrs (RC'F) clomiri;~te the hioliiass ol' l w ~ l t h i c cornn l t~~ l i t i cc (e.2. S t n ~ y c r et :(I. 1909. Va l~y l i n c t al. 1004). OLII- result\ clc~iionslr:~tcd that HI'F ii el-,: ; ~ l x ~ ~ l c l a ~ l t in I>ake I lonyt inghu iri tcrnis o f
304 X O ! L arid H -Z Wanq
-c. Lake
Fig. 6. i ' ~ I ! I I ~ ~ , I ~ I ' U ~ I ! . ' I (11,. I I I L , ~ ~ ~ O\L.I l:rli \\L.II I \IIIIIIII;II! \\L,III 01'1;1h~~ I ) c I I I ~ ~ ~ I ~ ~ I ~ I I \\ itll ~\\~Y;III:I/C Ri\.c~.-i\ol;~~e(I I;~kc\. IS . iri\ec( ' 1 8 ; g!.l~.i-. ( I \ " . i - I ~ ~ . ~ ~ . ~ x l \1:1.113~,1\. :\( '( ;. , I I I I I L~~ I~ ! ~ ~ o ~ ~ c L ~ I I ~ I - ~ . I I ~ I L ~ I . ~ ~ I ~ \ : I('( ;. ~ I I \ C C ~ ~ ~ ) ~ I L ~ L ~ ~ ~ I ~ - ~ ; I I ~ ~ L ~ I ~ c I . \ . BC'I.. hiv;rl\c ~~oll~~~.!ol.- l i l~el.-
. - - 1 1 I I I : - .LL. ! z . i i , . c ~ L l ~ ! I~~ , . IL . I \ . \ [ I ' \II~;III I I I W L I III-LY~,I!III-\ IIIIJ~II~! c~ I~ I I . I I I I~ I~~~( . \ ) : l.Il! l i r ~ ~ c i l i \ c ' ~ . l [>~-eclirtos\ !~l i i r i~iIy ocIo~i~~Le\l. i . I 1 ' 8 : li i l i~ / i \ c \I!'li\ \ I!I~. <IIL~I.II.! $ i \L.~. l :~ l i 111 \!)L,L.~c,\ \\ ill1111 1 1 1 ~ . ( i ~ l ~ ~ . ~ i o ~ ! i ~ l l '~ 'eJ i~~g s1.01111. TIic I'oo(\ \\.el1 01' I.;~kc' : ,. , . I . ; ; . . . . . , ' . l L - q l ~ ( l ~ ! ~ r I,) I : ; I i . 1 1 ?I~!I(II. .IIICI IIIO\L, 0 1 I.;II,L, I )OI~CI~LI \\c,I.c, ~ ' i ~ ~ c l 11.0111 1 ~ 1 ~ 1 & W L I I ~ ~ (20071.
, ~ , & . n ~ L l : i ~ t 3 c ~ ~ ~ 0 1 \ I ~ L ~ L : ~ C * \ LII~CI 13101i i ;1\ \ . , \ \~I)III:II. I>:II~CI.I~ \\;I\
l i ,~, !OLIIILI 111 I :II\C l ' o ! ;~~ i y l i ~~ . :IIIO~I~~I. 1 :~ l .y~ Y ; ~ ~ i y t / c ... ~~ . K~~.:I.-CIIIIIICC.~C(~ I;~ki' i\1.:;111y et ;11. 20071. 11111 1101 ill
\ s . . . L i / ~ - ~ \ ~ ~ l ; ~ ~ ~ ~ ~ I . . : ~ , ., - . 1:1k~\ (1 .1 & CLII 2OOi). \ ~ 1 y ~ e a 1 \
! ! ! ~ . ' \ i~tcr tlo\\ I\ 01 1111po1~1;1nec 111 \~I~LIL,~LII.~IIF hcn~h ic L ' : : ~ ~ ~ I ! I L I I I I I ~ L > \ i l l 1 t lootll>l;~in ei.osy\lclrl\. I3Ck arc alwn-
i : ~ 1 7 1 L ! ~ ~ ~ ~ i t i l ~ ~ ~ - ~ ~ ~ ~ \ : ~ c i c L . o L I ~ \ ~ ~ \ 111 ~ t ~ ~ : I l i i \ ! ~ ; I L I ~ ~ I ~ C t A . 7 .
:!)i~~i I . ;111~i p i ~ i ~ L ~ ~ l I I T I ~ O ~ ~ : I I ~ I IIIIC i n 1111trie111 I - L S ~ J ~ I ~ I I ~ : > : : : . ~ \ l i \ \ ;IICI~ L-L,O\> \tc111s i Hou ;II.LI 'Q (~~~ll ' l 'e! 2006). !-ii t- L:III !rcmo: i. 1 ~ 1 l - g ~ ;lmount\ 0 1 ' 1);11-(1clea fr-on1 tlic , \ .!!:-!~ .~C)I~ l~1~11 ~lll{i 11~;lll~t'el~ 111c\c re5oLlrL~c.~ 1 0 the 5L l l> -
\ ! I ~ ~ , : L :!\ h i o ~ l ~ \ i x ~ \ i t \ ! l.i~ccc\ i~ncl p \ c ~ ~ c l o l ~ ~ ~ e c e s ) . t l i ~ ~ \ !!I,;L , : ic \ t ~ \ p c ~ ~ ~ i ~ d II~LI~~I-I~LI :LL : t i l:thle 1.01- (IIII~I. Ihent l i i~
i i i l I I i C I I I I I - ~ I I BCC;ILI~C'
I ! ! : i ~ . ! l t111c1 I ' L ~ c c ! I I ~ ~ ~ i i o c l e , . RCF LIIY \C~);I~;I~C~I f1~11li ~ , , ! . L i t 1 1 ~ 2:1il)c1 L.I\ :11ic1 \< . I .L I~cI-~ ill t e r ~ i i \ 0 1 ' t ~ - ~ p I i i c . . , , ' t ' . i ' ! i ~ \ C>.\I~I~IIII\ 111 13~r1.t \\IIJ (Iiei:~~.! o \ e ~ ~ l ; q ~ \ Ix- I . ! : i I { ( i ,111tI l ~ l l l ~ ~ l ~ 1 1 ~ l l l i ~ l l ~ ~ L ~ ~ l l l \ L l l l l ~ l ~ \ :lI.Lx !(I\\ el.
: . , 1 / ! ( . 1 \ ( , ,IIIIG 1 1 1 - o i l IC'I III.~II~;II.J c . ~ I I I \ L I I ~ ~ ~ I . \ .
.... ,:I,, I>,II!L,! :I-. 111 1 1 1 ~ . 100,l \ \ L > I ~ o f 1.;1kc D o ~ i y ~ i ~ i y I i ~ ~ ! - I - I ; . ! ! : :,. ! ' I , [ ! I ' I l l C~iIlL'1. ll.~..I1\\ ;ltcl. I1clltliiL.
., , , l < L ~ ~ i i , ~ ~ <k \~ ' ; I I~ , IC ,L , 1007.
Kcnke c~ a . 2001. T h o ~ l l l x o n M Townsend 2003). r.i\,cr-i\olatc.I lal\ea (c.g. L i u c~ al. 2006. L i u & W i ~ n ?
2007 ) ancl [loncls ( Warren 1089). These inc,lucle h igh
levcls oI 'o~l ini\o~.!, ;~nt l energy concentr;rtctl i n :I small
n ~ ~ ~ n h e l . 01' I n k > . Ho\\:cvc.r. there are some clifti.~.ences 111 \vcl> \ t r ~ ~ c t~11.c :111io1iy thew ecosy\1e1iis. Fil.a~. spc-
cics conipo\i t ion 01' L ; ~ c D o n g t i n g h ~ ~ is cluite clifti.~.c.nt
I'rom that 0 1 ~.ivc~.-i\olatecl lakes and stl-ea~na. B i ~ a l v e ~ ~ o l l e c ~ t o r - l i l l e r e ~ ~ \ cloniirla1c the benthic c o m n i ~ ~ n i ~ y i n Lake I longiinghu. 13~11 co~np~. ise :I \m:~l l prcq1ortion 01' ~li:~~~.oin\crtc'b~.:~tea i n niany river-isolated I:tkea
:~nd str.c;~m>. Second. connec,~;rnce in he Yangtze Ri\.cl.-conne~~ccl lakc is hi2hc.r t h ~ l n that 01' atrealns
('To\vncncl ct :II. 1998. 'Tholnpson 24 Townsend 2003).
r i hile I o \ \ c~ - th:un that o f l 'angtze River-isolatecl lakes i l.iu c.1 al. 700h. L~LI Kr Wan: 2007) ;~nd poricls (Wal--
ren IVXV). l ' h i s s ~ ~ g ~ c s t s t11;1t con1lcct;~ncc incre;rsc'\
aa ecos!.strllla change f roni lot ic to lentic waters. 'T'hil-d. \\.ith .egal.cl to niche oveclap wrha. the cliet:u-y
o\crl :~pa wi th in :uid among FFGs are much lower ill I.;~he I lonyt inghu thiui tlioac in Y : ~ n g t ~ c River-ixol:~t-
~ . t l I:~kc\ I !-'iii. 6 1 ;uld \tre:tlns (Wc)odwarcl & Hi ld rcw
nth~c rnacro~~lvertebrates In a river connected lake 305 - --
more plarlklonic rn;~tcri;ll during the flood xcason tllull in otlicr periocl\. Plankton is abundant in Yanglre lakes cluring the Ilood season when water temperature i \ hiyh (Liang CQ L iu 1995). I t is also l ikely that the ~,l;~nktc>n ix \vasllecl o ~ ~ t ol' Ientic and low tlowing water hy IloocI w . ~ t e ~ ~ .
l*.oocl *cb s ( r ~ ~ e l ~ ~ r e also appea~.~ 10 be s imp l i t i d by t loodi~lg. Th i \ is xlio\\.n by a decrease in the number 01 \ l xc i c \ ant1 links in the Lake Dongtinghu food wet?. I-iigh c~ontlrctu~lcc values typically occurred in len- tic ~\ ;~lcrx I;OIII~;I~~CI with lotic habitats. Conncctance incrcasccl ;IS flooding increased in intensity in Lake
L~onyt ingh~r. Since t?enrhic predators decreased in den- \iry elul-il~y rhe floocling. food webs of those months reprc\cnr only primary consumers and excluded insect prcdarors. Strong cf'ccts exerted by flooding on the helltllic I.ocrd wch were ~ ~ l s o demonstrated by the de- crca\c of' niche overlap within and anlong FFGs dul-- ing rhc 1 1 0 ( , ~ 1 \eaxon. This indicates that although spe- cies co11\~1i1icel ;I \vide range o f food items during the Iloodi~lg. tllcy \;cc~nccl not to compete intensely with each o~her for f ~ o i l . Although floods have ctrong el'- fectx 011 bc;ltliic ~~i;~croil~vertebratcs. the benthic com-
munity typ~cal ly recovers quickly after flooding (Lake cr al. 7006). This \\;I\ the case in Lake Dongtinghu, as we S:IU LII~ incre;~se i t1 r~i:~c~-oi~ivel-tebrate cleusity and hic~~na\x the flood waters receded. The reco\/ery 01' 11lc bcn~l i ic ~ x ) ~ l l ~ i i ~ ~ t i i t y in the lake Inay be due to re- I'llgin in the floodplain ax a result of :I regular floocl rcginlc in t l ~ i s area.
Our r es~~ l t s pro~ic le ~ ~ s e f u l infortnation ~ r i t h regard to the ~-c\t:)r;~tioll o f benthic ~ii;~croinvertebrates in lake\ 011 tlic 'Iangt/c River floodplain. Connectivity is inlportant ill nl~tintaining a high level o f habitat hetero-
geneity :111cl species biodi\~crsity in lakes. Considering conser\atio~l of hiotliversity in Yangt~c Rivel--isolateel lal\c\. i t i x 11ecesx;11.y 10 incrc;1se the conncctiviry be- t\veell tlicxe lakcx ;lnd the Yangt/.c River. Also. natural Ilood reginlz play\ a11 ilnpnrtant role in structuring the benthic c o ~ ~ l r l i ~ ~ n i r y . Biodiversity conservation xh0~1Ic1 c.o~l\ider reconstructing rhe nuturol l low regime in Y;LII~IL~ Ki\-el--ixola~cd lakes. With regard to the Yang- r/e Ri\c~--connected l akc . the Icoric ;und low-flow 11-
gions in Lahe Ilongtinghu played ;ui importanr role in \upplying ft-oil\ fol. anilnala ol' filst-flow regionx c p e - cially during rhe Hood xeason. Consel-vation o f biodi- \.ersity i t i 'I i~ngt/e Ri\ er-counectccl lakes thus should mainrain 3 cert:lin proporliotl 01' Ientic or Io\v-don, \\ :Itel. Lll'ca.
Tllix sru~ly ix the lir\c ((1 xliow~ detailed informario~l o f trophic ~.:lation\hil>s amorlz hcnrhic ~nncroin\,crte- I>~.alc\ in X:ngtre Ki\'c~.-connec~ed I:tkex. Animal\ 1 .~~1
306 X.-Q LIU and H.-Z. Wang
~ i l ; ~ i n l > or1 i l c ~ r i l u \ ant1 a l so consun i c t l I;II-gc ;IIIIOLIII~S
~ l t ' plar ih ron. [_om foot1 \vcb c o n r i c c k ~ n c c and high Ic\ c l \ 0 1 o ~ i i ~ i i \ 01-! m e r e ~ ( I L I I I ~ ill L;the D o n g t i n g h ~ r .
.l'lic l'ooil \\.et> ;~ l )pc. ;~rcd t o b c hased on i l e t r i t ~ ~ s a n d
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Acknowledgements
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