Fatty acid composition of the Caprellidea (Crustacea: Amphipoda) from the Strait of Gibraltar

FATTY ACIDS OF THE CAPRELLIDEA (CRUSTACEA: AMPHIPODA) 501 SCI. MAR., 68 (4): 501-510 SCIENTIA MARINA 2004 Fa y acid composi ion o he Cap ellidea (C us acea: Amphipoda) om he S ai o Gib al a * JOSÉ MANUEL GUERRA-GARCÍA1, INÉS MARTÍNEZ-PITA1and MARÍA LUISA PITA2 1 Labo a o io de Biología Ma ina, Depa amen o de Fisiología y Zoología, Facul ad de Biología, Uni e sidad de Se illa, A da Reina Me cedes 6, 41012 Se illla, Spain. E-mail: [email p o ec ed] 2 Depa amen o de Bioquímica Médica y Biología Molecula , Facul ad de Medicina, Uni e sidad de Se illa, A da. Sánchez-Pizjuán 4, 41009 Se illa, Spain. SUMMARY: The o al a y acid composi ion o nine species o cap ellidean amphipods collec ed om he S ai o Gib al- a was in es iga ed. All cap ellids we e cha ac e ised by high le els o polyunsa u a ed a y acids, mainly eicosapen aenoic acid, 20:5(n-3), and docosahexaenoic acid, 22:6(n-3); o he majo a y acids we e he sa u a e palmi ic acid, 16:0, and he monounsa u a e oleic acid, 18:1(n-9). In spi e o his gene al uni o mi y, uni a ia e and mul i a ia e analysis showed ha Cap ella acan hi e a and C. g andimana di e ed om he emaining species (C. danile skii, C. equilib a, C. lipa o ensis, C. penan is, C. san os osai, Ph isica ma ina and Pseudop o ella phasma). These wo species (C. acan hi e a and C. g andi- mana) showed highe concen a ions o 18:1(n-7) and 20:4(n-6) and lowe pe cen ages o 22:6(n-3). These esul s, oge h- e wi h highe alues o he bioma ke a io 20:5(n-3)/22:6(n-3) and a lowe a io 18:1(n-9)/18:1(n-7), sugges ed a g ea e con ibu ion o dia oms and mac oalgae in he die o C. acan hi e a and C. g andimana and a lesse con ibu ion o lagel- la es han in he emaining species. The clus e classi ica ion o he cap ellid specimens om he S ai o Gib al a based on he a y acid composi ion was in ag eemen wi h he Clus e ou pu om da a o eeding beha iou . Sex- ela ed changes in he a y acid composi ion we e also explo ed in C. acan hi e a, C. danile skii and C. penan is; he pe cen age o 18:0, 20:4(n-6), and 20:5(n-3) was signi ican ly highe in males, whe eas 16:1(n-7) was highe in emales. The in aspeci ic di - e ences o a y acids in di e en en i onmen al condi ions seem o indica e ha he consump ion o dia oms in con as o lagella es inc eases wi h he deg ee o eu ophica ion. Key wo ds: a y acids, Amphipoda, Cap ellidea, S ai o Gib al a . RESUMEN: COMPOSICIÓN DE ÁCIDOS GRASOS DE LOS CAPRÉLIDOS (CRUSTACEA: AMPHIPODA) DEL ESTRECHO DE GIBRALTAR. – Se es udió la composición de ácidos g asos de nue e especies de an ípodos cap élidos ecolec ados en el Es echo de Gib al a . Todos los cap élidos se ca ac e iza on po p esen a ni eles ele ados de ácidos g asos poliinsa u ados, p incipal- men e eicosapen aenoico, 20:5(n-3), y docosahexaenoico, 22:6(n-3); o os ácidos g asos impo an es ue on el sa u ado ácido palmí ico, 16:0, y el monoinsa u ado ácido oleico, 18:1(n-9). A pesa de es e pa ón gene al, los análisis uni a ian es y mul i a ian es mos a on que, a endiendo a la composición de ácidos g asos, Cap ella acan hi e a y C. g andimana se di e encia on signi ica i amen e de las especies es an es (C. danile skii, C. equilib a, C. lipa o ensis, C. penan is, C. san- os osai, Ph isica ma ina y Pseudop o ella phasma). Es as dos especies (C. acan hi e a y C. g andimana) mos a on po - cen ajes más al os de 18:1(n-7) y 20:4(n-6) y más bajos de 22:6(n-3). Es os esul ados, jun o con alo es más al os del bio- ma cado 20:5(n-3)/22:6(n-3) y más bajos del 18:1(n-9)/18:1(n-7) sugie en una mayo con ibución de dia omeas y mac o- algas en la die a de C. acan hi e a y C. g andimana y una meno con ibución de lagelados. El dend og ama de clasi ica- ción de los cap élidos del Es echo de Gib al a basado en la composición de ácidos g asos ue simila al ob enido a pa i de los da os de compo amien o alimen icio de las especies. Los cambios en la composición de ácidos g asos con espec o al sexo ue on explo ados en C. acan hi e a, C. danile skii y C. penan is; el po cen aje de 18:00, 20:4(n-6), y 20:5(n-3) ue signi ica i amen e supe io en machos, mien as que el de 16:1(n-7) ue supe io en las hemb as. Las di e encias in aespe- cí icas en la composición de ácidos g asos en di e en es condiciones ambien ales pa ecen indica que el consumo de dia o- meas en e al de dino lagelados se inc emen a al aumen a el g ado de eu o ización. Palab as cla e: ácidos g asos, Amphipoda, Cap ellidea, Es echo de Gib al a . *Recei ed Oc obe 1, 2003. Accep ed Ap il 29, 2004. sm68n41877 7/12/04 11:30 Página 501 INTRODUCTION Cap ellidean amphipods a e small c us aceans which inhabi many li o al zones. They a e com- mon and di e se on e ec hyd ozoans and b y- ozoans, and on plan subs a a such as mac oalgae and seag asses (McCain, 1968). They eed on sus- pended ma e ials, p ey on o he o ganisms o g aze on epibio ic auna and lo a (Caine, 1974). Locally, cap ellids a e impo an p eys o many coas al ish species (Caine, 1989, 1991) and can be use ul as bioindica o s o wa e quali y (Gue a-Ga cía and Ga cía-Gómez, 2001). The S ai o Gib al a is an in e es ing zoogeo- g aphical a ea, especially om he poin o iew o he in e change o species be ween he A lan ic and he Medi e anean, and he Eu opean and A ican aunas. Recen ly, he Ma ine Biology Labo a o y o he Uni e si y o Se ille has been conduc ing esea ch p og ammes ocusing on axonomy, ecolo- gy and beha iou o he cap ellid communi ies o he S ai o Gib al a (Gue a-Ga cía, 2001a; Gue - a-Ga cía and Ga cía-Gómez, 2001; Gue a-Ga cía and Takeuchi, 2002; Gue a-Ga cía e al., 2002). The a y acid composi ion o ma ine amphipods is known o be ela ed o wa e empe a u e and eeding modes (Kawashima e al., 1999; G ae e e al., 2001) and a a y acid app oach can be use ul o explo e habi a p e e ences and eeding s a egies. Howe e , he e is a lack o s udies dealing wi h he a y acid composi ion in he Cap ellidea. Da a o a y acids ha e been eco ded only in i e cap ellid species be o e his s udy, all o hem collec ed om Japanese wa e s (Kawashima e al., 1999): an uniden i ied cap ellid species and ou o he species (C. acan hogas e , C. danile skii, Cap ella mu ica and C. penan is) inhabi ing O suchi and Mu su Bays in no he n Japan. The objec i e o his pape is o analyse he a y acid composi ion o a ious cap ellid species om he S ai o Gib al a and o explo e he sex- ela ed changes and he in aspeci ic a ia ions in a y acids depending on he en i onmen al condi ions. These aspec s had no been s udied in Cap ellidea be o e his s udy. MATERIAL AND METHODS S udy a ea The S ai o Gib al a is si ua ed on he bo de o he Medi e anean Sea and he A lan ic Ocean. Th ee a eas o di e en en i onmen al cha ac e is- ics we e selec ed o sampling he cap ellids: El Po il and Ta i a island in sou he n Spain, and Ceu a in no h A ica (Fig. 1). El Po il is loca ed in he es ua y a ea o he i e Pied as. The place is subjec o impo an luc ua ions in salini y and empe a u e and ecei es a conside able o ganic en ichmen due o he i e in luence. A e age wa e empe a u es in summe a e close o 25ºC (Gue a-Ga cía e al., 2000a). In con as , Ta i a island, as a pa o a Na - u al Pa k, is a e y well p o ec ed a ea cha ac e ised by clean and coole wa e s (mean alues o abou 17ºC in summe ) and highly biodi e se ma ine ben- hic communi ies (Gue a-Ga cía and Ga cía- Gómez, 2000; Gue a-Ga cía e al., 2000b). Ceu a is loca ed on he no h A ican side o he S ai o Gib al a and he wa e empe a u e in summe is 502 J.M. GUERRA-GARCÍA e al. FIG. 1. – Map o he S ai o Gib al a showing he sampling locali ies: El Po il, Ta i a and Ceu a. sm68n41877 7/12/04 11:30 Página 502 abou 19-20ºC (Gue a-Ga cía, 2001b). The deg ee o human in luence in he li o al a ea o Ceu a is in e media e be ween he Ta i a island (no an h o- pogenic in luence) and El Po il (a high le el o an h opogenic in luence). The e o e, in selec ing hese h ee a eas, a ange o condi ions is encom- passed o check in aspeci ic a iabili y in he a y acid composi ion. Sample collec ion Nine species o cap ellid amphipods we e sam- pled o he s udy (Table 1). The specimens we e collec ed by hand in in e idal a eas and using sno kelling and scuba di ing in in ali o al zones. Immedia ely a e sampling, he indi iduals we e so ed in o species and s o ed a –80 ºC o la e analysis. Fa y acid analysis Samples o he di e en species o cap ellids (25-30 mg) we e homogenised wi h 0.9% NaCl. Fa y acid me hyl es e s we e p epa ed by a di ec anses e i ica ion eac ion acco ding o Lepage and Roy (1987): 2 ml o me hanol-benzene 4:1 ( / ) was added o 0.2 ml o homogena e and hen, while s i - ing, 0.2 ml o ace yl chlo ide was slowly added. Tubes we e igh ly closed and main ained a 100ºC o 1 h. A e cooling, 5 ml o 6% K2CO3solu ion was added. The ubes we e hen shaken and cen- i uged and an aliquo o he benzene uppe phase was injec ed in o he ch oma og aph o a y acid analysis. Analysis o a y acid me hyl es e s was pe - o med by gas-liquid ch oma og aphy using a Hewle Packa d 5890 gas ch oma og aph equipped wi h a 30 m long x 0.25 mm in e nal diame e TR- WAX used silica capilla y column (Teknok oma, Ba celona, Spain). Peaks we e iden i ied by com- pa ison wi h known s anda ds (Supelco, Belle on e, PA, USA), and he esul s we e epo ed as a ea pe - cen ages. Bioma ke a ios Based on he a y-acid composi ion, a a ie y o bioma ke s and a ios we e de e mined o ob ain in o ma ion on die a y composi ion, ophic le el and eeding beha iou . The o al pe cen age o polyunsa - u a ed (PUFA) and sa u a ed (SFA) we e calcula ed. The a io 18:1(n-9)/18:1(n-7) has been p oposed as a ela i e measu e o ca ni o ous die in ma ine in e - eb a es (Falk-Pe e sen e al., 2000; Auel e al., 2002). In addi ion, he a ios 16:1(n-7)/16:0 and 20:5(n-3)/22:6(n-3) we e assessed, which allows di - e en ia ion be ween a dia om- o lagella e-based die (Nelson e al., 2001; Auel e al., 2002). FATTY ACIDS OF THE CAPRELLIDEA (CRUSTACEA: AMPHIPODA) 503 Table 1. Cap ellids om he S ai o Gib al a used o he s udy. De ails o locali y, da a, dep h and subs a a a e gi en. [n=numbe o samples; each sample con ains a numbe o specimens enough o chemical analysis (25-30 mg)] Species Locali y Da e Dep h Subs a a Cap ella acan hi e a Leach, 1814 Ta i a (n=9) May, 2002 In e idal Co allina elonga a, Gelidium pusillum, Halop e is scopa ia Ceu a (n=2) Augus , 2002 5 m Cys osei a ama isci olia Cap ella danile skii Cze nia skii, 1868 Ceu a (n=33) Augus , 2002 In e idal Cys osei a ama isci olia, C. usneoides Cap ella equilib a Say, 1818 El Po il (n=1) Ap il, 2002 In e idal Bugula ne i ina Cap ella g andimana Maye , 1882 Ta i a (n=2) May, 2002 In e idal Co allina elonga a, Gelidium pusillum, Halop e is scopa ia Cap ella lipa o ensis Halle , 1879 Ceu a (n=2) Augus , 2002 5 m Cys osei a ama isci olia Cap ella penan is Leach, 1814 Ta i a (n=3) May, 2002 In e idal Gelidium sesquipedale Ceu a (n=4) Augus , 2002 In e idal Cys osei a ama isci olia, C. usneoides El Po il (n=1) Ap il, 2002 In e idal Bugula ne i ina, Cys osei a sp. Cap ella san os osai Sánchez-Moyano, Ceu a (n=3) Augus , 2002 5-10 m Sphae ococcus co onopi olius Jiménez-Ma ín & Ga cía-Gómez, 1995 Ph isica ma ina Slabbe , 1769 Ceu a (n=3) Augus , 2002 5-30 m Cys osei a ama isci olia, Halop e is scopa ia, Gymnangium sp. Pseudop o ella phasma (Mon agu, 1804) Ceu a (n=2) Augus , 2002 25-30 m Gymnangium sp El Po il (n=2) Ap il, 2002 In e idal Bugula ne i ina, Cys osei a sp. sm68n41877 7/12/04 11:30 Página 503 S a is ical analysis The possible di e ences in he a y acid compo- si ion be ween species, oge he wi h he in aspeci - ic di e ences be ween sexes and sample si es, we e es ed. The da a was e i y o no mali y using he Kolmogo o -Smi no es and Le ene’s es was used o check he homogenei y o a iances. P o id- ed ha he e was no no mali y and/o homogenei y o a iances, he non-pa ame ic K uskal-Wallis es was used. The a ini ies be ween species based on he a y acid composi ion we e es ablished h ough Clus e analysis using he UPGMA me hod (unweigh ed Pai G oup Me hod using a i hme ic A e ages) (Snea h and Sokal, 1973). An MDS (non- me ic Mul idimensional Scaling) analysis was also conduc ed and he K uskal s ess coe icien was calcula ed o es he o dina ion (K uskal and Wish, 1978). The P ime compu e package .5 (Cla ke and Go ley, 2001) and he p og am PC-ORD (PC- O dina ion) . 3.05 (McCune and Me o d, 1997) we e used o mul i a ia e analyses. Fo uni a ia e analyses he BMDP (BioMedical Da a P og ams) was used (Dixon, 1983). RESULTS A de ailed desc ip ion o mean alues o a y acid pe cen ages oge he wi h he bioma ke a ios is gi en in Table 2 and Figu es 2 and 3. A leas 29 a y acids wi h a numbe o ca bon a oms om 14 o 22 we e p esen in he s udied cap ellid species. Unsa u a ed acids we e he majo a y acids, accoun ing o 69-75% o o al a y acids. Polyun- sa u a ed a y acids (PUFA) we e he dominan unsa u a ed a y acids, making up 50% o he o al a y acids. Eicosapen aenoic acid (20:5(n-3)) and docosahexaenoic acid (22:6(n-3)) we e he wo majo PUFA; o he majo a y acids ound in all cap ellid species we e palmi ic acid (16:0) and oleic acid (18:1(n-9)). In gene al, he a y acid composi ion was simila in all species (Table 2). Howe e , he pe cen age o 504 J.M. GUERRA-GARCÍA e al. TABLE 2. – Pe cen age o a y acid composi ion in he Cap ellidea om he S ai o Gib al a . Cap ella Cap ella Cap ella Cap ella Cap ella Cap ella Cap ella Ph isica Pseudop o ella acan hi e a g andim. danile skii equilib a lipa o . penan is san os osai ma ina phasma 14:0 1.62 1.52 2.21 2.56 2.79 1.86 3.21 2.62 3.26 15:0 0.68 0.66 0.29 0.61 0.53 0.40 0.62 0.65 1.11 16:0 17.88 17.59 23.10 18.13 18.75 19.23 18.09 16.14 19.77 16:1(n-7) 5.48 5.06 5.16 9.94 8.72 5.68 9.01 8.88 7.08 16:2(n-4) 1.36 1.91 0.70 2.15 1.00 1.61 0.78 3.01 1.40 17:0 0.99 1.16 0.45 1.20 0.84 0.82 0.98 1.00 1.32 18:0 3.80 3.53 3.31 4.56 4.10 4.16 4.81 4.94 5.08 18:1(n-9) 11.07 10.99 13.57 11.44 10.75 13.73 10.73 13.17 11.03 18:1(n-7) 6.70 7.23 1.96 3.00 1.88 2.19 2.43 2.09 2.61 18:1(n-5) 0.80 1.12 0.42 1.33 0.79 1.14 0.65 2.33 0.90 18:2(n-6) 1.79 1.47 4.22 2.07 1.74 2.63 1.85 1.80 1.59 18:3(n-6) 0.56 0.36 0.40 0.31 0.32 0.42 0.35 0.35 0.35 18:3(n-3) 1.52 1.18 0.90 0.95 0.82 0.55 0.83 1.02 1.51 20:1(n-9) 0.91 0.52 1.05 0.52 1.28 1.12 1.18 1.37 1.30 20:1(n-7) 0.74 0.46 0.26 0.46 0.23 0.29 0.23 0.22 0.38 20:2(n-6) 0.52 0.42 0.81 0.42 0.73 0.87 0.75 0.73 0.71 20:3(n-6) 0.49 0.31 0.13 0.31 0.19 0.11 0.20 0.15 0.13 20:4(n-6) 10.00 10.25 2.87 2.33 3.59 3.89 3.38 2.42 2.79 20:3(n-3) 0.58 0.36 0.25 0.43 0.40 0.26 0.43 0.36 0.40 20:4(n-3) 0.25 0.20 0.68 0.49 0.46 0.34 0.44 0.51 0.46 20:5(n-3) 20.57 21.45 15.19 17.04 18.84 16.40 19.39 15.18 12.80 21:5(n-3) 0.24 0.16 0.43 0.32 0.48 0.29 0.45 0.39 0.33 22:0 0.39 0.38 0.26 0.29 0.34 0.31 0.42 0.41 0.23 22:1(n-9) 0.26 0.25 0.18 0.23 0.33 0.21 0.35 0.28 0.16 22:2(n-6) 0.53 0.55 0.51 0.92 0.66 0.55 0.50 0.45 0.80 22:4(n-6) 0.96 1.20 0.19 0.34 0.36 0.28 0.29 0.33 0.48 22:5(n-6) 0.80 0.51 0.25 0.47 0.62 0.47 0.70 0.49 1.00 22:5(n-3) 0.71 1.47 0.44 1.07 0.78 0.70 0.75 0.68 0.99 22:6(n-3) 7.78 7.72 19.87 15.31 17.70 19.47 16.18 18.02 20.00 To al sa u a es 25.37 24.84 29.61 27.00 27.35 26.79 28.14 25.77 30.78 Sum monounsa u a es 25.97 25.63 22.60 26.92 23.97 24.37 24.58 28.34 23.46 Sum polyunsa u a es 48.66 49.53 47.85 46.08 48.68 48.85 47.29 45.89 45.76 To al unsa u a es 74.63 75.16 70.45 73.00 72.65 73.21 71.86 74.23 69.22 Sa u a es/Unsa u a es 0.34 0.33 0.42 0.36 0.38 0.37 0.39 0.35 0.44 sm68n41877 7/12/04 11:30 Página 504 FATTY ACIDS OF THE CAPRELLIDEA (CRUSTACEA: AMPHIPODA) 505 FIG. 2. – Mean alues and s anda d de ia ions o he pe cen age o he dominan a y-acids measu ed in he s udied cap ellid species. Ca: Cap ella acan hi e a; Cd: C. danile skii; Ce: C. equilib a; Cg: C. g andimana; Cl: C. lipa o ensis; Cp: C. penan is; Cs: C. san os osai; Pm: Ph isica ma ina; Pp: Pseudop o ella phasma. Signi ican di e ences we e ound in C. acan hi e a and C. g andimana wi h espec o he o he se en species o 18:1(n-7), 20:4(n-6), 22:6(n-3) (*, p<0.05). sm68n41877 7/12/04 11:30 Página 505 506 J.M. GUERRA-GARCÍA e al. FIG. 3. – Mean alues and s anda d de ia ions o he bioma ke a ios measu ed in he s udied cap ellid species. Ca: Cap ella acan hi e a; Cd: C. danile skii; Ce: C. equilib a; Cg: C. g andimana; Cl: C. lipa o ensis; Cp: C. penan is; Cs: C. san os osai; Pm: Ph isica ma ina; Pp: Pseudop o ella phasma. Signi ican di e ences we e ound in C. acan hi e a and C. g andimana wi h espec o he o he se en species o 18:1(n-9)/18:1(n-7) and 20:5(n-3)/22:6(n-3) (*, p<0.05). FIG. 4. – MDS o dina ion o he cap ellid species acco ding o he a y acid composi ion. Do ed lines ci cles indica e he g oups ob ained wi h he Clus e analysis (Fig. 5). Scale ba s: 1 mm. sm68n41877 7/12/04 11:30 Página 506 he a y acids 18:1(n-7) and 20:4(n-6) we e signi i- can ly highe in C. acan hi e a and C. g andimana han in he emaining species (K uskal-Wallis es , p<0.05). Signi ican di e ences we e also ob ained o he pe cen age o 22:6(n-3), which was lowe in C. acan hi e a and C. g andimana (Fig. 2). The bioma ke a io 18:1(n-9)/18:1(n-7) was sig- ni ican ly lowe in C. acan hi e a and C. g andi- mana han in o he species, whe eas he a io 20:5(n-3)/22:6(n-3) was highe (K uskal-Wallis es , p<0.05) (Fig. 3) When he a y-acid ma ix was used in he mul- i a ia e analyses o explo e he simila i y be ween species, he pa e n ob ained wi h he uni a ia e analysis was con i med (Fig. 4 and 5). Cap ella acan hi e a and C. g andimana we e clea ly sepa- FATTY ACIDS OF THE CAPRELLIDEA (CRUSTACEA: AMPHIPODA) 507 FIG. 5. – Dend og am o simila i y be ween he cap ellid species, p oduced om pe cen age da a o a y acids. FIG. 6. – Pe cen age o ou selec ed a y acids in males and emales o Cap ella acan hi e a, C. danile skii and C. penan is. The alues a e exp essed as mean and s anda d de ia ion (numbe o pools, n=3-4). Signi ican di e ences in he ou a y acids be ween males and emales we e ob ained (*p<0.05, **p<0.01). sm68n41877 7/12/04 11:31 Página 507 a ed om he emaining species in bo h he MDS o dina ion ou pu (Fig. 4) and he dend og am (Fig. 5). The Clus e analysis based on he Euclidean dis- ance showed ha wo species g oups can be di e - en ia ed (Fig. 5). The i s includes C. acan hi e a and C. g andimana, cha ac e ised by highe con- en s o 18:1(n-7) and 20:4(n-6) and lowe con en s o 22:6(n-3). The second g oup can be spli in o wo subg oups: he species C. penan is and C. danile skii in one subg oup, and C. equilib a, C. san os osai, C. lipa o ensis, Ph isica ma ina and Pseudop o ella phasma in he o he subg oup; he i s subg oup was cha ac e ised by sligh ly highe concen a ions o 16:0 and 18:2(n-6) han he second subg oup. Sex- ela ed in luence on a y acid composi ion Wi h espec o he in aspeci ic a ia ion be ween males and emales, da a we e only a ailable o he species C. acan hi e a, C. danile skii and C. penan- is. Signi ican di e ences we e ound o he h ee species be ween males and emales in he pe cen - age o 16:1(n-7), 18:0, 20:4(n-6) and 20:5(n-3). The amoun o 16:1(n-7) was signi ican ly highe in emales whe eas he 18:0, 20:4(n-6) and 20:5(n-3) pe cen ages we e signi ican ly highe in males (K uskal-Wallis es , p<0.05) (Fig. 6). In aspeci ic a ia ion o a y acids Only he species Cap ella penan is was collec ed in he h ee s udy a eas (Ta i a, Ceu a, El Po il). Cap ella acan hi e a was ound in Ta i a and Ceu a bu no in El Po il, and Pseudop o ella phasma was collec ed om Ceu a and El Po il bu specimens om Ta i a we e no a ailable o his s udy. The e was a common pa e n o a ia ion in wo o he majo a y acids, 16:1(n-7) and 22:6(n-3), o he h ee cap ellid species (Fig. 7). I we conside a g owing g adien o eu ophica ion om Ta i a o El Po il, an inc ease in he pe cen age o 16:1(n-7) and a dec ease in 22:6(n-3) could be obse ed. DISCUSSION In he p esen s udy he o al a y acids o he cap ellid specimens we e analysed. Some p e ious s udies (e.g. Kawashima e al. 1999) di e en ia ed he a y acids o phospholipids om he a y acids o iacylglyce ols. Howe e , G ae e e al. (2001) showed ha he di e ences be ween he a y acid composi ion o phospholipids as s uc u al compo- nen s o memb anes and iacylglyce ols as s o age lipids a e small. These au ho s p oposed ha u u e s udies o ben hic amphipods should be done wi h analysis o he o al lipid a y acid composi ion. Fou majo a y acids cha ac e ised he a y acid p o ile o he s udied cap ellid species, namely 16:0, 18:1(n-9), 20:5(n-3) and 22:6(n-3). These we e also he mos abundan a y acids desc ibed in a ious species o he wo o he amphipods g oups, gamma ids and hype ids (Cla ke e al., 1985; Phlege e al., 2000; Sco e al., 2001; Nelson e al., 2001; Auel e al., 2002; Co eia e al. 2003) 508 J.M. GUERRA-GARCÍA e al. FIG. 7. – Compa ison o he pe cen age o 16:1(n-7) and 22:6(n-3) along an inc easing g adien o eu ophica ion om Ta i a (unpollu ed a ea) and El Po il (eu ophic a ea) in he cap ellids Cap ella acan hi e a, C. penan is and Pseudop o ella phasma. A ows indica e ha he species was no collec ed om ha a ea. The alues a e exp essed as mean and s anda d de ia ion. sm68n41877 7/12/04 11:31 Página 508 al hough in some species high le els o 16:1(n-7) (G ae e, 2001) o 20:1(n-9) (Auel, 2002) ha e also been ound. The a y acid composi ion o cap ellids has only been p e iously epo ed in a s udy ca ied ou by Kawashima e al. (1999) in no he n Japan. Cap el- lids om he S ai o Gib al a showed a a y acid composi ion simila o ha desc ibed o he Japan- ese cap ellids, excep o 18:1(n-9) and 20:5(n-3), which showed lowe alues in he species collec ed in he S ai o Gib al a . These di e ences may be ela ed o di e ences in wa e empe a u e, as i has been epo ed ha he amoun o 20:5(n-3) inc eas- es when wa e empe a u e dec eases (Kawashima e al., 1999). In he p esen s udy he pe cen age o 20:5(n-3) measu ed in he cap ellid species om Ta i a (cha ac e ised by colde wa e s, 17 ºC in sum- me ) anged om 18 o 22%, whe eas in he species om El Po il (cha ac e ised by wa me wa e s, 25 ºC in summe ) anged om 11 o 17%. These anges seem o suppo he in luence o he empe a u e on a y acid composi ion, al hough he numbe o specimens om El Po il is small, so he da a mus be aken cau iously. In addi ion o he empe a u e, he ype o die could also be in ol ed in hese a i- a ions, as discussed la e . The p esen s udy shows ha he a y acid com- posi ion o he species Cap ella acan hi e a and C. g andimana di e ed om ha o he o he se en species. These wo species we e cha ac e ised by signi ican highe pe cen ages o 18:1(n-7) and 20:4(n-6) and lowe alues o 22:6(n-3). These di - e ences we e also e lec ed in some bioma ke a ios. Cap ella acan hi e a and C. g andimana showed highe alues o he a io 20:5(n-3)/22:6(n- 3) and lowe alues o he a io 18:1(n-9)/18:1(n-7). Among he speci ic lipid componen s sugges ed o use as ophic bioma ke s, high le els o he a y acids 16:1(n-7), 18:1(n-7), 20:5(n-3) a e conside ed o be an indica o o a dia om-based die (G ae e e al., 2001; Nelson e al., 2001; Auel e al., 2002). In con as , lagella es usually con ain high concen a- ions o 22:6(n-3) (Sa gen e al., 1987; G ae e e al., 1994; Sco e al., 2000), whe eas 20:4(n-6) o igina es om mac oalgae and is inco po a ed unmodi ied in he lipids o he amphipod (G ae e e al., 2001). The a y acid 18:1(n-9) is conside ed o be an indica o o a mo e ca ni o ous die (Nelson e al., 2001) and has been associa ed wi h nec ophage species (G ae e e al., 2001). The e o e, he combi- na ion o a highe 20:5(n-3)/22:6(n-3) a io, a lowe 18:1(n-9)/18:1(n-7) a io and highe pe cen ages o 20:4(n-6) sugges s ha he e is a g ea e con ibu- ion o dia oms and mac oalgae in he die o C. acan hi e a and C. g andimana han in ha o he emaining species. The a y acid 20:1(n-9) is also conside ed o be an indica o o ca ni o ous die a y inpu (Hopkins e al., 1993; Vi ue e al., 2000; Sco e al., 2001) and in some species o a c ic hype ids (Auel e al., 2002) high le els o 20:1(n-9) ha e been epo ed. In his s udy, he pe cen age o 20:1(n-9) ound in he s udied cap ellids was e y low (0.52-1.05%), which indica es ha he copepod con ibu ion o he die o hese species is e y low o inexis en . The dend og am ob ained in he p esen s udy based on he a y acid composi ion (Fig. 5) is in ag eemen wi h he dend og am ep esen ed by Gue a-Ga cía e al. (2002) based on he clinging beha iou associa ed wi h eeding s a egies. The species C.danile skii and C. penan is spend mos o hei ime in a “pa allel” pos u e on he subs a e, eeding mainly by sc aping, and bo h species a e g ouped oge he in he eeding clus e (Gue a-Ga - cía e al., 2002). Simila ly, Ph isica ma ina, Pseudo- p o ella phasma, C. equilib a and C. san os osai a e in he same g oup because hey ha e a simila eed- ing beha iou , il e ing and p eda ing in an “up igh ” posi ion. In he a y-acid clus e ou pu , hese species a e also e y close based on simila pe cen ages o a y acids. The e o e, i seems ha a y acid composi ion is signi ican ly ela ed o eeding modes in cap ellids. Al hough he a ailable da a o di e en ia ing he a y acid composi ion in males and emales a e sca ce, se e al clea pa e ns we e ob ained o h ee o he nine s udied species. The pe cen age o 18:0, 20:4(n-6), and 20:5(n-3) was signi ican ly highe in males o he h ee compa ed species (C. acan hi e a, C. danile skii and C. penan is), whe eas 16:1(n-7) was highe in emales. Simila pa e ns (excep o 18:0) ha e been epo ed ecen ly o he gam- ma idean amphipod Gamma us lacus a (Co eia e al., 2003). These di e ences in a y acid composi- ion could e lec sligh di e ences in eeding s a e- gies, such as he g ea e consump ion o dia oms by he emales, maybe due o ep oduc i e pu poses. Co eia e al. (2003) also ound age- ela ed changes in he a y acid composi ion in Gamma us lacus a. The pe cen age o 16:1(n-7) dec eased wi h age, while 18:1(n-9), 20:1(n-9) and 20:1(n-11) inc eased in adul specimens, al hough he age- ela ed changes seem o be ela ed o he pe oxida ion s a us o he animals in gamma ids (Co eia e al., 2003). Fu he FATTY ACIDS OF THE CAPRELLIDEA (CRUSTACEA: AMPHIPODA) 509 sm68n41877 7/12/04 11:31 Página 509