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DIVERSITY AND HABITAT PREFERENCE OF AQUATIC INSECTS 49 DIVERSITY AND HABITAT PREFERENCE OF AQUATIC INSECTS ALONG THE LONGITUDINAL GRADIENT OF THE MACAÉ RIVER BASIN, RIO DE JANEIRO, BRAZIL BAPTISTA, D. F., BUSS, D. F.,, DORVILLÉ, L. F. M., ad NESSIMIAN, J. L. Departameto de Biologia, IOC, Fiocruz, Av. Brasil, 4.65, CEP 45-9, Maguihos, Rio de Jaeiro, Brazil Laboratório de Etomologia, Departameto de Zoologia, CCS, UFRJ, C.P , CEP , Ilha do Fudão, Rio de Jaeiro, Brazil Colégio de Aplicação e Faculdade de Formação de Professores, UERJ Correspodece to: Darcílio F. Baptista, Departameto de Biologia, IOC, Fiocruz, Av. Brasil, 4.65, CEP 45-9, Maguihos, Rio de Jaeiro, Brazil, Received Jauary, Accepted April 8, Distributed May, (With figures) ABSTRACT Diversity ad habitat preferece of macroivertebrates were studied i Macaé River basi, Rio de Jaeiro State, Brazil, alog its logitudial gradiet. We selected stream reaches correspodig to st, d, 4 th, 5 th ad 6 th orders. A Surber sampler was used to collect four macroivertebrates samples of each substrate (sad, litter i pool areas, stoes, ad litter i riffle areas) durig the three samplig periods, defied based o the rai regime: April (ed of the raiy seaso), July (dry seaso), ad October (begiig of the raiy seaso). We idetified 46,4 specimes correspodig to 7 taxa. Aalysis of diversity umbers (both for family or geus level) idicated that all isect taxoomic orders had higher umbers o d order stream reach, except for Ephemeroptera, o 4 th order. However whe cosiderig morphspecies taxoomic level, the higher diversity umber occurred o 4 th order stream. The highest richess ad diversity umbers were foud at the dry seaso. Cosiderig habitat preferece, both litter i pool areas ad litter i riffle areas had the highest faual richess. Key words: diversity, aquatic isects, logitudial gradiet, tropical river, Brazil. RESUMO Diversidade e preferêcia de isetos aquáticos por habitats o gradiete logitudial a bacia do Rio Macaé, RJ, Brasil A diversidade e a preferêcia de isetos aquáticos por habitats foram estudadas o gradiete logitudial da bacia do Rio Macaé o Estado do Rio de Jaeiro, Brasil. Foram selecioados trechos de rio correspodetes a a, a, 4 a, 5 a e 6 a ordes. Foram amostrados três períodos, abril, julho e outubro, represetado o fial da estação chuvosa, a estação seca e o começo da outra estação chuvosa, respectivamete. Um total de 46.4 espécimes de isetos aquáticos foram obtidos. Em cada mês, quatro amostras foram coletadas utilizado um amostrador do tipo Surber para cada substrato: areia, folhas depositadas em áreas de remaso, folhas em áreas de corredeiras e pedras. O padrão geral observado quato às medidas de diversidade, cosiderado o úmero de gêeros ou famílias, idicou que todas as ordes de isetos aquáticos apresetaram seus maiores valores o trecho de a ordem, exceto para Ephemeroptera, que foi registrado em 4 a ordem. No etato, quado cosiderou-se uma meor resolução taxoômica (morfo-espécies), o pico de diversidade ocorreu em 4 a ordem. A maior riqueza e abudâcia ocorreram durate o período de seca. Quato à preferêcia por habitat, os folhiços de fudo e de correteza, em particular, foram os que apresetaram os maiores valores de riqueza. Palavras-chave: diversidade, isetos aquáticos, gradiete logitudial, rio tropical, Brasil. Rev. Brasil. Biol., 6(): 49-58 5 BAPTISTA, D. F. et al. INTRODUCTION A great deal of research has bee doe o the use of aquatic macroivertebrates i water quality biomoitorig programs ad i assessig evirometal impacts i the USA as well as i may Europea coutries (Metcalfe, 989; Roseberg & Resh, 99). Several cost-effective methods for water quality assessmet have bee developed, like the Rapid Assessmet Protocols RAP (Resh & Jackso, 99). The adequate applicatio of such methodologies require, for each situatio, previous kowledge about may aspects of lotic macroivertebrates, which are still lackig i Brazil. Thus, it is importat to uderstad temporal ad spatial patters of macroivertebrates alog the logitudial gradiets of brazilia rivers, as well as their distributio ad abudace amog differet habitat types. This kid of iformatio allow the determiatio of the most represetative habitats i each situatio, the degree of taxoomic resolutio to be employed, ad the umber of samples to be take (Plafki et al., 989). Rivers ca be studied o a variety of spatial scales (see Frissell et al., 986). Whe the focus is o the distributio amog differet habitats, a compariso ca be made betwee erodig ad depositig habitats, like riffles ad pools areas. O a broader scale, chages i ecological patters ca be recorded alog the river, as well as i differet river basis. Most of these studies have show that local patters are almost ever reproduced idetically i other streams (Viso & Hawkis, 998). I this way, the processes structurig aquatic isect assemblages i the differet substrate types, already described ad better evideced i rivers located i temperate areas (Rabei & Mishall, 977; Mishall & Mishall, 977), should be tested ad compared with those detected i tropical ad subtropical rivers (Aruachalam et al., 99; Dudgeo, 98, 994; Kikuchi, 996). Therefore, specific methodologies ca be developed ad adapted to these areas. Baptista et al. (998a) observed that aquatic isect assemblages alog the Macaé River basi preset a faual disrupture alog its logitudial gradiet, separatig upper (upstream 4 th order reaches, aroud 7 m a.s.l.) from lower (5 th ad 6 th orders) stream reaches. The aim of this study was to record the temporal variatio of diversity ad habitat preferece of aquatic isects alog a river system i Southeaster Brazil. MATERIAL AND METHODS Study area The study area comprises the Macaé River basi, i the State of Rio de Jaeiro, Brazil. This is a medium size river (6 th order i the estuary) with about km, placed i the coastal slope of the Serra do Mar ( o ', o 8 S ad 4 o 7', 4 o 5 W). Five statios were chose alog this river system from the upper rhytro sectio to the upper potamo, represetig st, d, 4 th, 5 th, ad 6 th orders stream reaches. The first two statios were located at the Flores River (a tributary of the Macaé River), with, ad, m a.s.l., respectively. All the other statios were placed alog the Macaé River. A detailed descriptio of the area is available i Baptista (998), ad Baptista et al. (998a). Macroivertebrates A stratified radom samplig desig was employed for aquatic isect collectios. Samplig was carried out i April, July ad October 995, correspodig to the ed of the raiy seaso, the dry seaso, ad the begiig of the raiy seaso, respectively. I each statio four samples were take from each of the followig habitat types: sad (A); litter deposited i pool areas (), litter held i riffle areas (), ad stoes (S) (except o 6 th order). Thus, a total of 76 samples were take i each moth ad 8 i the whole study. All isects were collected usig a Surber sampler (9 cm area ad µm mesh size) ad were preserved i the field i a % formaldehyde solutio, buffered with % borax. I the laboratory all specimes were sorted, idetified, couted uder stereoscopic microscopes, ad preserved i 8% ethaol. As the idetificatio of aquatic isects to species level i South-easter Brazil is ot possible i most cases, specimes were assiged to Operatioal Taxoomic Uits (OTUs) that represeted the lowest taxoomic level that could be reached by meas of the keys provided by Merritt & Cummis (988), Domiguez et al. (99), Triviho- Strixio & Strixio (995), Froehlich (984) ad Beedetto (974), ad/or with the aid of taxoomists. Rev. Brasil. Biol., 6(): 49-58 DIVERSITY AND HABITAT PREFERENCE OF AQUATIC INSECTS 5 Such fact resulted i some OTUs idetified i higher taxoomic levels havig a higher abudace tha others i lower levels, which might have bee resposible for some bias i the data. Specimes of the Order Blattaria ad the Family Staphyliidae (Coleoptera) were icluded i this study despite their semi-aquatic habits. I each samplig statio three diversity idices were estimated for each isect order separately due to the differet levels of taxoomic resolutio obtaied: Margalef richess idex, Shao-Wieer diversity idex, ad Pielou eveess idex, accordig to Ludwig & Reyolds (988). The aquatic isect distributio amog the four habitat types was recorded both by meas of their abudace as well as by their desity (expressed as the percetage of total specimes). I additio, the total umber of OTUs was obtaied for each habitat. RESULTS Diversity measures alog the logitudial gradiet The highest richess ad diversity umbers were obtaied i d or 4 th stream orders for all isect orders. This patter was observed at all samplig occasios (Fig. ). Cosiderig the logitudial gradiet of the stream, oly a few taxa occurred at all sites. For example, the isect order Plecoptera exhibited 5 taxa, but oly Aacroeuria had a wide distributio. The whole order had the highest diversity ad richess umbers i d order stream reach. The ephemeropteras showed a differet patter, as the highest richess umbers was obtaied i 4 th order reach, while its highest abudace was foud i 5 th order. Four geera occurred alog the stream gradiet: Pseudocloeo, Leptohyphes, Cloeodes, ad Farrodes. Some geera were predomiat i the upper reaches (Ulmeritus, Miroculis, Massartela ad Askola), while Lachlaia boaovae ad Hageulopsis were foud oly i 6 th order stream reach. From the eightee trichoptera geera foud, fiftee were exclusive of the upper reaches. The geera Phylloicus, Smicridea ad Polycetropus had a wide distributio (from st to 6 th stream orders), ofte associated with litter i pools substrate. The highest diversity umbers were foud i d order stream reach. Odoata had the higher diversity i low order stream reaches, i particular, d order. Coleoptera ad Diptera were idetified oly to family level, but chiroomids were idetified to subfamily or tribe level. For both Coleoptera ad Diptera, high diversity umbers were foud i medium stream reaches, specially i 4 th order. Habitat preferece Substrate distributio ad abudace The complete list of aquatic isects foud i this study ca be cosulted i Baptista (998) ad Baptista et al. (998a). PLECOPTERA We ca cosider that the whole order occurred preferetially i litter substrates, both deposited i pools () ad held i riffle areas (), ad i upper stream reaches. The geus Aacroeuria was the domiat taxo i i the upper reach presetig a desity of 79% (of a total of 49 idividuals), 5% (of 75) ad 4% (of idividuals), respectively, i the three samplig occasios. O the other had, the geus Kempyia, was most ofte foud i. The most represetative groups were foud i 4 th order streams ad there was o temporal substitutio i domiace (Fig. a). EPHEMEROPTERA This isect order exhibited a higher abudace i the lower reaches, preferetially i riffle areas. The species Hylister plaumai was the domiat taxo i i April, represetig 46.% of the total (5 idividuals). I July, durig the dry seaso, ephemeropteras were most ofte foud i i the upper reach, with the geus Farrodes cotributig with 5% (664 idividuals). I October, there was a high domiace i riffle areas, with % (,75 idividuals) beig foud i stoy substrates i the lower reach (5 th order stream). The geus Pseudocloeo was the domiat taxo i this substrate with 74.% (57 idividuals). Ephemeropteras, differetly from the plecopteras, showed a temporal substitutio for each substrate (Fig. a). TRICHOPTERA The highest abudace of Trichoptera was exhibited i, i the upper reach, i all samplig occasios. I April, 54% of the trichopteras were foud i ad the geus Triplectides was the domiat taxo, represetig 7.4% of the 898 specimes collected. I July, specimes foud i represeted 46% of the total i this moth ad the geera Triplectides ad Notalia were the most abudat groups (with 7.8% ad.8% of,7 idividuals, respectively). I October, oce more, was the most importat substrate with 47.4% of the specimes collected. Rev. Brasil. Biol., 6(): 49-58 5 BAPTISTA, D. F. et al. April Jue October Coleoptera Diptera Odoata Trichoptera Ephemeroptera Plecoptera Stream Order Richess Diversity Eveess Fig. Richess (idex of Margalef), eveess (Pielou) ad diversity (idex of Shao) values for each isect order i the three samplig periods alog the logitudial gradiet. Rev. Brasil. Biol., 6(): 49-58 DIVERSITY AND HABITAT PREFERENCE OF AQUATIC INSECTS 5 6 Plecoptera 5 4 Sad Stoe 7 6 Ephemeroptera 5 4 Sad Stoe Trichoptera,, Sad Stoe Fig. a Abudace of Plecoptera, Ephemeroptera ad Trichoptera foud at each substrate (sad, litter i pool areas, stoe ad litter i riffle areas ), comparig the upper ad lower stream reaches, i the three samplig periods. The geus Phylloicus was the domiat taxo, cotributig with 4.% of the total (Fig. a). The highest abudace of the whole order was foud i 4 th order stream. ODONATA There was a marked preferece for areas of low water flow, otably, with 4% (April), 46.% (July) ad 5% (October), ad for the upper reaches. It was observed a temporal substitutio of the domiat taxo i each substrate. I April, the geus Haeteria represeted 49% (4 idividuals), i July, the domiat taxo of this substrate was Argia, with 44.7% (67) ad i October, Limetro had the highest abudace with 4.6% (55 specimes) (Fig. b). COLEOPTERA The family Elmidae was the domiat taxo i all substrates. However, it occurred preferetially i i the lower reaches, i April, ad i the same substrate but i the upper reaches i July ad October. I geeral, this particular family represeted more tha 5% of the total umber of idividuals for each substrate i the three samplig occasios (Fig. b). HEMIPTERA There was a preferece for depositio areas (sad ad ). I April, 45.6% of the total idividuals were foud i sad substrate i the upper reaches. The geus Neotrephes (75% of 5 idividuals) was the domiat taxo i this substrate. I July, the substrate had 4.5% of Rev. Brasil. Biol., 6(): 49-58 54 BAPTISTA, D. F. et al. the hemipteras, ad Neotrephes had 56% from 57 idividuals collected. I October, Neotrephes was a domiate i was, cotributig with 77.7% of the 7 specimes (Fig. b). DIPTERA Dipteras had a great variatio i abudace amog the substrates ad samplig occasios. There was o clear habitat preferece, with high abudace i sad, ad. The Chiroomii (Chiroomidae, Chiroomiae) was the domiat taxo i the sad substrate i the upper reaches (with 6.% of,84 idividuals) i April. I July, the dipteras were more abudat i i the lower reaches ad the domiat taxa were Chiroomii, Simuliidae ad Orthocladiiae, with 54.%, % ad % (of 5,6 idividuals), respectively. I October, there was a high occurrece i upper reaches. I overall terms, the order Diptera had the highest abudace i 5 th order stream reaches. Substrate ad stream order abudace ad richess patters The variatio amog the three samplig periods is show i Table. The higher abudace of macroivertebrates i the upper reaches ( st to 4 th orders streams) occurred i pool areas, i ad sad. Together, the two substrates cotribute with more tha 7% of the idividuals foud i the ed of raiy seaso (April) ad i the dry seaso (July). I the begiig of the raiy seaso (October) there was a reductio i abudace i these substrates. I geeral, ad had the highest taxoomic richess. The substrate had its highest richess umbers (54 taxa) i 4 th order stream reach i October, ad the lowest umbers (8 taxa) i st order i July. O the other had, had the highest richess (5 taxa) i d order stream i July, ad the lowest ( taxa) i st order i October. The sad substrate despite of high geeral abudace, had the lowest umber of taxa at the upper reaches. Also, the pool area substrates (sad ad ) showed the highest richess umbers durig the dry seaso ad the lowest durig the raiy seaso (Table ). I 5 th order, differetly from the upper reaches, fast flow substrates ( ad stoe) had higher abudace tha depositioal areas ( ad sad). DISCUSSION Diversity measures alog the logitudial gradiet Our results idicate that almost all isect orders had their highest richess ad diversity umbers at the upper reaches, where Plecoptera, Trichoptera, Odoata, Coleoptera ad Diptera occurred predomiatly at d order, while Ephemeroptera had a preferece for 4 th order stream reach. This results were obtaied whe based o the taxoomic level of family or geus. However, if cosiderig morph-species, the highest diversity umber for the whole isect commuity occurred i 4 th order (Fig. ). Stout & Vadermeer (975) workig i streams i Colombia ad Costa Rica also foud high diversity at medium to upper reaches. Accordig to Viso & Hawkis (998), high diversity at this areas are related to higher habitat heterogeeity ad complexity. Also, the River Cotiuum Cocept (Vaote et al., 98) suggest that the higher habitat heterogeeity at medium reaches will allow a higher diversity i streams. We foud some isect groups (e.g. Trichoptera ad Coleoptera) presetig may shredder ad scraper species at the upper stream reach, what suggest that these groups are very importat i the trasformatio of the allochthoous particulate orgaic matter that will be trasported ad used by dowstream commuities. Thus, evirometal disturbaces i these areas affectig such groups may lead ot oly to a great local diversity loss but also to alteratios i the dowstream biota (Cummis & Klug, 979). Habitat preferece Substrate distributio ad abudace Accordig to Ladle & Ladle (99) the preferece for oe substrate or aother is determied first by the ovipositio behavior of the orgaism but this distributio may be modified later by passive drift or active migratio. High richess ad diversity were foud durig the dry seaso, possibly due to a higher habitat stability ad availability. The richest substrates (i geeral, litter substrates), durig this seaso, are less affected by water flow, allowig a greater period for coloizatio ad processig of bethic orgaic matter by macroivertebrates. Also, the commuity established i stoy substrates ad sad substrates become more stable servig as refugia for youger orgaisms. Although there was a occupatio i all substrates, there was a clear preferece for oe or two specific substrates, ad. Rev. Brasil. Biol., 6(): 49-58 DIVERSITY AND HABITAT PREFERENCE OF AQUATIC INSECTS Sad Odoata Stoe Sad Hemiptera Stoe Sad Coleoptera Stoe Fig. b Abudace of Odoata, Hemiptera ad Coleoptera foud at each substrate (sad, litter i pool areas, stoe, ad litter i riffle areas ), comparig the upper ad lower stream reaches, i the three samplig periods. Litter substrates are preferred by may taxa because they offer best shelter ad feedig coditios due to the high habitat heterogeeity ad a rich periphytic flora. O the other had, i sad substrates the istability of the substrate ad the low orgaic matter availability lead to a low diversity ad richess umbers (Hawkis, 984). Thus the habitat heterogeeity is a very importat factor ifluecig macroivertebrates distributio i streams (Viso & Hawkis, 998). Similar results were foud i other South-easter Brazil streams (Hery et al., 994). Peak (978) foud that Plecoptera i North America streams, occur preferetially associated with stoy substrate. Our study does ot corroborate this patter as the two most abudat geera foud i Macaé basi (Aacroeuria ad Kempyia) occurred predomiatly i litter substrates ( ad respectively). The ephemeropteras were most ofte foud i fast flowig substrates ( ad stoe). Accordig to Maca (978), the behavior of stream species should be related to the velocity of flow, as fast waters should trasport more utriets i a determied Rev. Brasil. Biol., 6(): 49-58 56 BAPTISTA, D. F. et al. period. This would allow may ephemeroptera filterfeedig species to occur. Besides, the preferece for these substrates are also related to a high availability of dissolved oxyge cocetratios. Despite of the highest richess umber of Ephemeroptera foud at 4 th order stream, its highest abudace was foud at 5 th order, probably due to the icrease of two geera (Leptohyphes ad Pseudocloeo). Yet, oe ca ot affirm (as they are filterfeeders ad collectors, respectively) if the observed patter was a result of the atural gradiet or due to high suspe
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