5/22/2016  |   10:30 - 10:45   |  306

PRACTICAL LEVELS OF IDENTIFCATION FOR LARVAE OF BAETIS (EPHEMEROPTERA: BAETIDAE) IN NORTH AMERICA The small minnow mayfly genus Baetis consists of 19 species in North America and occurs in nearly all lotic systems, with several species often occurring together. The taxonomic target for larvae in many bioassessment protocols is species but larvae for 6 of the 19 species are either undescribed or inadequately described to allow identification and it is likely these have been incorrectly identified as species included in available keys. Furthermore, recent studies show deep genetic divergence within most species, indicating that the current classification may not reflect the actual diversity of the genus. Based on available genetic data and new morphological data, we refine previously defined species groups, propose species complexes, and provide additional diagnostic characters for inadequately described species. The use of hierarchical levels for identification of bioassessment samples allows finer resolution identifications for damaged and early instar specimens that would normally be left at genus and more accurately represents species richness and autecological traits within a sample.

Jeff Webb (Primary Presenter/Author), Rhithron Associates, Inc, jwebb@rhithron.com;


Sean Sullivan ( Co-Presenter/Co-Author), Rhithron Associates, Inc, ssullivan@rhithron.com;


Luke Jacobus ( Co-Presenter/Co-Author), Indiana University-Purdue University Columbus, lmjacobu@iupuc.edu;


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5/22/2016  |   10:45 - 11:00   |  306

THE ROLE OF TEMPORAL STRUCTURE IN AQUATIC INSECT GENETICS: A CASE STUDY IN POPULATIONS OF BAETIS TRICAUDATUS Baetis tricaudatus is an abundant, widespread, and ecologically important multivoltine benthic macroinvertebrate common in biomonitoring programs. Studies on the genetics of this species have found intraspecific divergences greater than that expected for a single species; however, no studies have been done in northern California and none have examined the temporal patterns of population structuring. Objectives for this study were to examine the genetic structure of COI in B. tricaudatus populations in the Russian River watershed to: assess overall genetic diversity; explore temporal patterns of population structure; and compare results from different sample sizes. The maximum difference found at COI among 293 specimens was 1.8%. The same two dominant haplotypes were consistent through years, sites, and seasons. Two intensive samplings of more than 30 individuals captured 1.4% and 1.2% difference, suggesting that a single intensive sampling event, in comparison to longer-term monitoring events, may capture most of the diversity for this species. In contrast to other studies, our results suggest that Russian River populations of B. tricaudatus constitute a single species with no evidence of cryptic diversity.

Natalie Stauffer-Olsen (Primary Presenter/Author), UC Berkeley, natjst@berkeley.edu;


Patrick O'Grady ( Co-Presenter/Co-Author), UC Berkeley, ogrady@drosophilaevolution.com;


Vincent Resh ( Co-Presenter/Co-Author), University of California, Berkeley, resh@berkeley.edu;


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5/22/2016  |   11:00 - 11:15   |  306

PATTERNS OF MICROBIAL DECOMPOSER DIVERSITY ALONG ALTITUDINAL GRADIENTS IN TROPICAL AND TEMPERATE STREAMS Microbial decomposer diversity is expected to be higher towards the tropics and at lower sites along altitudinal gradients. In the tropics taxa turnover is expected to be higher than in temperate zones. To test these hypotheses we established altitudinal gradients based on 5 streams in both the tropics (Napo, Ecuador) and temperate zone (Colorado, USA), and assessed rDNA for aquatic fungi (ITS2) and bacteria (V3) applying the denaturing gradient gel electrophoresis (DGGE) technique. Aquatic fungi diversity, measured as operational taxonomic units (OTUs) increased with elevation in Ecuador and peaked at mid altitudes in Colorado. Diversity was related with higher concentrations of PO4 and moderate concentrations of NO3, respectively. Fungal richness was the same in Ecuador and Colorado (t-test; p = 0.2), but fungal identity differed (NMDS). Bacteria OTUs in Ecuador and Colorado decreased with altitude and were correlated with NO3 and temperature. Beta diversity of aquatic fungi and bacteria were lower in Ecuador than in Colorado (ANOSIM). Our results suggest that broad elevation and latitudinal patterns observed on large organisms might not be similar for aquatic microorganisms.

Cristina Salgado (Primary Presenter/Author, Co-Presenter/Co-Author), MARE, Dept. Life Sciences, Faculty of Science and Technology, University of Coimbra, Portugal , cris_salgadomg@yahoo.com;


Andrea C. Encalada ( Co-Presenter/Co-Author), Instituto BIOSFERA, Universidad San Francisco de Quito, Cumbayá, Ecuador Biológicas y Ambientales, Universidad San Francisco de Quito, Cumbaya, Ecuador, aencalada@usfq.edu.ec;


Cláudia Pascoal ( Co-Presenter/Co-Author), Center of Molecular and Environmental Biology (CBMA). Dept. of Biology, University of Minho, Campus de Gualtar, Portugal., cpascoal@bio.uminho.pt;


Fernanda Cássio ( Co-Presenter/Co-Author), Center of Molecular and Environmental Biology (CBMA). Dept. of Biology, University of Minho, Campus de Gualtar, Portugal., fcassio@bio.uminho.pt;


Alexander Flecker ( Co-Presenter/Co-Author), Cornell University, Ithaca, NY, USA, asf3@cornell.edu;


LeRoy Poff ( Co-Presenter/Co-Author), Colorado State University, n.poff@rams.colostate.edu;


Manuel Graça ( Co-Presenter/Co-Author), MARE, University of Coimbra, Portugal , mgraca@ci.uc.pt;


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5/22/2016  |   11:15 - 11:30   |  306

HIGH UNEXPLAINED VARIANCE IN COMMUNITY DATA? SPATIAL AUTOCORRELATION MIGHT BE THE KEY: EVIDENCE FROM MACROINVERTEBRATES IN AGRICULTURAL WETLANDS Anthropogenic disturbances within agricultural wetlands can stimulate dispersal events of aquatic macroinvertebrates, which can influence community composition through to taxon-specific differeneces in dispersal abilities. Spatial autocorrelation (SA) of species composition among sites, whereby closer sites have more similar species composition, might mask the effects of important environmental variables or treatment effects. Thus far, hardly any studies of macroinvertebrate communities in agricultural wetlands have considered SA effects. We investigated SA effects on macroinvertebrate responses to various water chemistry variables, such as dissolved oxygen and nutrient levels, which have been shown in other studies to affect community composition. We examined macroinvertebrate community composition in nine agricultural wetland sites at Lai Chi Wo, Hong Kong, on 6 sampling occasions encompassing both wet and dry seasons. SA variables were generated using inter-site distances. The best models for both seasons included only SA variables, which explained on average 20% of community variance. We therefore urge explicit consideration of SA during community modeling and hypothesis tests involving wetland mactroinvertebrates, in order to increase the proportion of variance explained and enhance understanding of underlying ecological drivers.

Ying Kin Ken So (Primary Presenter/Author), School of Biological Sciences, the University of Hong Kong, Hong Kong, u3500795@hku.hk;


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5/22/2016  |   11:30 - 11:45   |  306

HABITAT CONNECTIVITY AND ORGANISMS’ DISPERSAL ABILITY DRIVE THE ASSEMBLY MECHANISMS OF MACROINVERTEBRATE COMMUNITIES IN RIVER NETWORKS Habitat connectivity and organisms’ dispersal ability play a key role in shaping stream communities. We examined the effects of habitat connectivity and dispersal ability on the assembly of stream macroinvertebrate communities. Using null models, we compared the structural turnover of communities among streams with different degrees of habitat connectivity and for groups of species with different dispersal ability. Communities in the most isolated headwater streams were more dissimilar than expected by chance, indicating niche filtering and dispersal limitation as the assembly mechanisms. Communities in the most connected mid-order streams were more similar than expected by chance, suggesting homogenization through mass effects. Weak flyers were more dissimilar than expected by chance in isolated streams, while communities of strong flyers were more similar than expected by chance or did not differ from random. Strong flyers may be assembled through mass effects independently of environmental variability and habitat connectivity, while environmental sorting and dispersal limitation are likely the main assembly mechanisms for weak flyers. Our results highlight the fundamental roles of habitat connectivity and dispersal abilities in shaping species distributions within river networks.

Romain Sarremejane (Primary Presenter/Author), Nottingham Trent University, romain.sarremejane02@ntu.ac.uk;


Heikki Mykrä ( Co-Presenter/Co-Author), University of Oulu, heikki.mykra@oulu.fi;


Timo Muotka ( Co-Presenter/Co-Author), Ecology and Genetics Research Unit, University of Oulu, Finland, timo.muotka@oulu.fi;


Jukka Aroviita ( Co-Presenter/Co-Author), Finnish Environment Institute (Syke), jukka.aroviita@ymparisto.fi;


Nuria Bonada ( Co-Presenter/Co-Author), University of Barcelona, bonada@ub.edu;


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5/22/2016  |   11:45 - 12:00   |  306

DO POOLS IMPEDE STREAM INSECT DRIFT DISPERSAL? The dispersal of biota between populations is a key factor influencing the persistence of populations. In rivers, identifying constraints to drift dispersal between habitat patches is critical for greater understanding of the spatial extent of populations, recolonization and river restoration. We determined whether stream insects drifting between riffle habitats (i.e. patches of suitable habitat) were impeded by pools (i.e. unsuitable habitat), limiting dispersal to the next downstream riffle. We measured invertebrate drift entering and exiting each of 13 pools, focusing on 13 species. We found that for 10 species, drift dispersal between riffles was significantly reduced by the intervening pool habitat, with the baetid, Offadens hickmani, showing the greatest reduction in drift numbers (60% reduction). The dispersal between riffle habitats for 9 species was related to one or more aspects of pool morphology. These relationships were consistent with the prediction that dispersal was increasingly impeded with greater areas of low or zero velocity within pools. Our results demonstrate that the drift of stream insects between habitat patches is limited by the intervening pool hydraulic conditions and individual species drift behaviors.

Andrew Brooks (Primary Presenter/Author), Department of Primary Industries - Water, New South Wales, Australia, andrew.brooks@dpi.nsw.gov.au;


Ben Wolfenden ( Co-Presenter/Co-Author), N/A, Benjamin.Wolfenden@environment.nsw.gov.au;


Barbara Downes ( Co-Presenter/Co-Author), The University of Melbourne, barbarad@unimelb.edu.au;


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