Biomass Dynamics of Tipula (Insecta: Diptera) in Forested Streams of the Interior Highlands, Arkansas Samuel B
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View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by ScholarWorks@UARK Journal of the Arkansas Academy of Science Volume 60 Article 12 2006 Biomass Dynamics of Tipula (Insecta: Diptera) in Forested Streams of the Interior Highlands, Arkansas Samuel B. McCord Arkansas State University, [email protected] Alan D. Christian Arkansas State University Richard S. Grippo Arkansas State University Follow this and additional works at: http://scholarworks.uark.edu/jaas Part of the Entomology Commons Recommended Citation McCord, Samuel B.; Christian, Alan D.; and Grippo, Richard S. (2006) "Biomass Dynamics of Tipula (Insecta: Diptera) in Forested Streams of the Interior Highlands, Arkansas," Journal of the Arkansas Academy of Science: Vol. 60 , Article 12. Available at: http://scholarworks.uark.edu/jaas/vol60/iss1/12 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact [email protected]. Journal of the Arkansas Academy of Science, Vol. 60 [2006], Art. 12 Interior Highlands, Arkansas '' ' ' Samuel B. McCord ,AlanD. Christian , and Richard S. Grippo i Environmental Sciences Program, P.O. Box 847, State University, AR 72467 2 Department ofBiological Sciences, P.O. Box 599, State University, AR 72467 3 Mactec Engineering and Consulting, Inc., 3199 Riverport Tech Center Rd., St. Louis, MO 63043 4 Correspondence: [email protected] Abstract.—Abundance patterns of aquatic macroinvertebrates that utilize coarse particulate organic matter as a food source are important indicators ofnon-point source pollution— associated —with silviculture activities. This group, referred to as shredders, typically decreases inabundance as its food source primarily leaves is removed from the ecosystem. We tested whether larval biomass ofthe crane fly Tipula, a common member of the group, was an effective estimator of shredder abundance. Additionally, weused regression analysis to test whether the length to dry mass relationship ofTipula differed among geographic regions, between seasons, and between years. Results did not indicate significant differences inthe relationship among these variables. Thus, we concluded that a general length to dry mass relationship was appropriate for Tipula in streams of the Interior Highlands. Our results were similar to those reported from North Carolina and Virginia. Tipula biomass was positively correlated with the total richness of the macroinvertebrate assemblage, a common measurement of stream quality, but was not correlated with the numerical abundance ofthe shredder functional feeding group. Thus, we concluded that Tipula biomass would not be an effective surrogate for whole assemblage metrics inbiological assessments. — Key words: aquatic macroinvertebrates, non-point source pollution,silviculture, Tipula, InteriorHighlands, Arkansas. Introduction The principal hypothesis of the cause ofthe shift is that removal of the —forest canopy —deprives the system ofan important energy Silviculture is a major land use inArkansas; over 55% ofthe source leaf inputs and results in greater insolation of the state's land cover is commercial forest (AFC 2002). InArkansas stream bottom, stimulating algal growth (Campbell and Doeg as in other states, biological assessments are performed to 1989). examine the impacts of non-point source (NPS) pollution, and Important members of the shedder group are Tipula spp. one of the potential sources of NPS pollution is silviculture (crane flies). This genus has more than 30 species in North activity. Biological assessments can be effective in testing America (Byers 1996), and as aquatic larvae, they primarily whether stream impairment is associated with NPS pollution feed on decomposing plant material and associated microflora (Rosenberg and Resh 1993). Standard biological assessment (Pritchard 1983). Tipula spp. are some of the major shredders, requires collecting samples representing the entire invertebrate particularly in terms of biomass, in streams of the Interior community ofstreams inthe watershed ofinterest and comparing Highlands (SBM pers. obs.). Most other regional representatives characteristics of that community to an unimpaired reference ofthis functional feeding group are either small taxa (e.g. capniid, condition. Whole community samples are recommended in leuctrid, and nemourid stoneflies and the chironomid genera order to make this sampling methodology adaptable enough to Cricotopus and Polypedilum) or are larger taxa typically found detect various types ofenvironmental degradation (Barbour et al. in low numbers (e.g., limnephilid and phryganeid caddisflies; 1999). However, these samples require significant investments Merrittand Cummins 1996). ofmoney and time to collect and analyze (Davidson and Clem Tipula individuals go through four larval instars (Pritchard 2002). Anassessment procedure that reduces the time and cost 1983). Mean length at the end ofeach instar has been reported— spent per sample, but retains the ability to detect environmental for Tipula sacra from—Alberta, Canada, as—follows: first instar impairment, is desirable. For assessments ofpotential silviculture 5 mm, second instar 14 mm, thirdinstar 20 mm; fourth instar impacts, focus upon the abundance and biomass dynamics ofthe females reached 50 mm and males reached 30 mm(Pritchard and shredder functional feeding group may be a solution. Hall 1971). Pritchard (1976) reported adult Tipula emergence in Studies of the effects of forest clearing have frequently Alberta through June and July withadults livingless than a week. noted compositional shifts in aquatic invertebrate communities Eggs hatched in a few days, withsecond instar larvae appearing in streams of the cleared watershed, most often as a reduction a few weeks later. They spent about 3 months as a second instar in the abundance of the shredder functional feeding group, with before molting to the third in November and overwintered as corresponding increases in the collector and/or scraper groups thirdinstars. Most individuals molted tothe fourth instar inApril (Newbold et al. 1980, Noel et al. 1986, Stone and Wallace 1998). and May. He found firstinstar larvae inJuly through September, Journal ofthe Arkansas Academy ofScience, Vol.60, 2006 74 Published by Arkansas Academy of Science, 2006 74 s Journal of the Arkansas Academy of Science, Vol. 60 [2006], Art. 12 Biomass Dynamics of Tipula (InsectarDiptera) inForested Streams of the InteriorHighlands, Arkansas and they were the most abundant instar inJuly. Second instar time, i.e., between seasons and between years. in larvae were present in all months except May and June and Tipula spp. are often the major holometabolous shredder were most prominent in August and early September. Third forested, low-order, Interior Highland streams, many of which instar larvae were present from August through the following are temporary streams (Poulton and Stewart 1991,Moulton and June and were numerically dominant from mid-September to Stewart 1996). Holometabolous taxa have been observed tohave May. Fourth instar larvae were collected inall months and were higher growth ratios than hemimetabolous species (Cole 1980), numerically dominant in June. The typical Tipula life cycle is which may be advantageous for exploiting ephemeral habitats semivoltine with the second year spent as a fourth instar larva like those prevalent in the Interior Highlands. That is, fast (Pritchard 1983). However, Pritchard (1980) hypothesized some growth may be an adaptive advantage in streams that typically cohort splitting may occur in the fall after hatching with most cease flowingfor at least a few months every year. individuals overwintering as third instars, but some others grow Thus, the purpose ofthis study was to address the following rapidly to fourth instar and overwinter in that stage questions: Researchers addressing ecological questions at various 1) Do Tipula length to dry mass relationships differ among scales recognize invertebrate biomass as an important variable geographically separate streams, between seasons, or between (Benke et al. 1999). However, Rogers et al. (1976) noted that years? Do they differ among larval instars? while insect biomass is an important piece of information, 2) Do power equations developed for Interior Highland direct massing is too timeconsuming tobe practical. Therefore, Tipula spp. conform to those derived from other sources? estimation ofbiomass is frequently performed using length to 3) Would Tipulabiomass be useful as abiomonitoring toolfor mass conversion ratios (Burgherr and Meyer 1997). Acommon detecting decreased CPOM inputs associated withsilviculture? method ofperforming this conversion is touse regression analysis, 4)Does seasonal growth for Tipula occur faster intemporary typically after log-transformation ofraw data, and describe mass streams than in permanent streams? as a power function of length (Rogers et al. 1976, Sample et al. 1993, Hodar 1996). Length to mass power functions have been developed for aquatic dipterans