Spatial distribution of epiphytic chironomid larva

Authors: Monika TarkowskaKukuryk

Publish Date: 2014/02/07

Volume: 15, Issue: 2, Pages: 141-153

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Abstract

Four submerged macrophytes were analysed with their respective assemblages of chironomid and algal taxa Studies were made bimonthly from January to November in a shallow macrophytedominated lake The periphytic algal community was represented by chlorophytes diatoms and cyanobacteria diatoms showed the highest relative abundance on the macrophyte species during the study Algal biomass was affected by the season and in January the highest values were found on Stratiotes aloides L Potamogeton lucens L Myriophyllum spicatum L in July on Chara aculeolata Kütz The lowest algal biomass on most of the macrophytes studied was found in September Larvae of Dicrotendipes sp Diplocladius cultriger Kieffer Endochironomus albipennis gr Endochironomus impar Walker Glyptotendipes sp and Paratanytarsus austriacus Kieffer were dominant within the chironomid community The spatial distribution of chironomids between macrophytes species was related to periphytic algae biomass and certain environmental variables temperature water transparency biomass of chlorophytes and diatoms Analysis of chironomid diet and the results of canonical correspondence analysis confirmed this relationship The strongest chironomidalgae relationships were observed on S aloides and P lucensIn lakes whose water is clear species and morphological diversity of submerged macrophytes may affect the distribution and structure of epiphytic invertebrates Macrophytes exhibit variations in structural architecture and determine the habitat area available for colonisation by invertebrates Cyr and Downing 1988 van de Meutter et al 2008 Plants with dissected leaves such as Ceratophyllum demersum Myriophyllum spicatum are often more complex owing to the high ratio of surface area to plant mass thus it has been suggested this complexity increases the number of microhabitats and overall niche space for associated invertebrates Warfe and Barmuta 2004 Hansen et al 2011 The distribution of invertebrates between macrophyte species is also related to potential food resources periphytic algae Many groups of invertebrate grazers use periphytic algae as a major food resource one of the most important is chironomid larvae Peets et al 1994 Balci and Kennedy 2003 TarkowskaKukuryk 2011 Although the larvae are able to ingest a variety of food types including algae detritus and associated microorganisms and macrophytes Pinder 1986 Hirabayashi and Wotton 1999 commonly reported food items are periphytic algae Lawrence and Gresens 2004 Tall et al 2006 Maasri et al 2010High chironomid grazing pressure may substantially reduce the biomass of periphytic algae Jones and Sayer 2003 TarkowskaKukuryk 2013 For this reason chironomid larvae may act as an important topdown regulator of periphyton biomass and the removal of periphyton by grazing larvae may improve light conditions for macrophytes Periphytic algae may attenuate most of the light reaching the adaxial leaf surface and decrease the production of macrophyte species markedly up to 60–80  Thus periphyton is an important competitor of macrophytes for light carbon and nutrients and may negatively affect the growth of the hosting macrophyte Vermaat and Hootsmans 1994 Liboriussen et al 2005 Accumulation of periphytic algae is usually greater on thick and finely branched submerged plants such as Myriophyllum or Ranunculus than on largeleaved pondweeds Potamogeton Blindow 1987 Laugaste and Reunanen 2005 Understanding the algaechironomid relationship of different macrophyte species requires an analysis of chironomid dietThe colonisation of macrophyte species by periphytic algae and chironomids may also be stimulated by fish Intensive fish foraging may substantially reduce the number of grazers Brönmark et al 1992 McCollum et al 1988 The refuge effect of macrophytes is particularly evident in clearwater lakes and depends on the macrophyte species Koperski 1998 and Rantala et al 2004 have stressed the role of the macrophyte species Stratiotes aloides as an effective shelter against predator pressure similarly dense characean stands may prevent intensive fish foraging James et al 2000 These highly developed green algae tend to cover the sediment in dense mats which resemble meadowsTo date a number of field and laboratory studies have focused on the relationships between plant morphology substrate surface habitat complexity and associated invertebrates Lalonde and Dowing 1991 Taniguchi et al 2003 Tessier et al 2004 BecerraMunoz and Schramm 2007 Hansen et al 2011 Only a few considered the structure and biomass of periphytic algae as a factor potentially determining the selection of macrophyte species by invertebrates Dvorak 1996 Cattaneo et al 1998 The significant contribution of environmental variables on chironomid variability is already known Brooks et al 2001 showed that chironomid assemblages in lakes of the northwest of England are structured by total phosphorus TP dissolved oxygen lake depth Secchi disc transparency and water temperature in polluted waterbodies the most important variables are dissolved oxygen and food availability Lindegaard 1995 The chironomids associated with the common reed Phragmites australis Cav Trin ex Steud are mostly affected by nutrients epiphytic chlorophylla periphyton biomass reed density and total organic carbon CañedoArgüelles and Rieradevall 2009 TarkowskaKukuryk 2011 Nevertheless the determinants governing spatial distribution of chironomid species between macrophytes in clearwater lakes are still not well recognisedDuring the study the following hypotheses were tested that in a macrophytedominated lake 1 the morphological structure of macrophytes determines the colonisation area and availability of food resources periphytic algae for chironomids 2 the distribution of chironomids between macrophyte species is affected by the macrophyte species and the composition of periphytic algae and 3 the relationships between macrophytes and associated chironomid larvae are affected by environmental variables water temperature Secchi disc transparency oxygen content nutrientsThe general objectives of the study were as follows 1 to describe the taxonomic composition and abundance of periphytic algae and of chironomid larvae on four macrophyte species with different morphological structures 2 to identify algal taxa in the guts of the dominant chironomid taxa and to compare them with the composition of the periphytic algae and 3 to determine the environmental habitat conditions affecting the distribution of chironomids between macrophyte species

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