Macroalgal communities from an acid mine drainage impacted watershed

Twenty-eight streams were sampled seasonally and a subset of 10 streams was sampled monthly for one year throughout the Hocking River drainage basin, Ohio, USA. Streams ranged from those receiving acid mine drainage (AMD), to reclaimed sites, to those never receiving mine wastes. Physical and chemic al parameters were measured and macroalgal taxa were collected with estimat ions of percent cover. Canonical correspondence analysis showed AMD and sea sonal parameters to be influential in grouping streams and macroalgal commu nities. The macroalgal composition was only useful in distinguishing betwee n heavily impacted AMD streams and all others. We were unable to utilize th e macroalgal community to detect differences among reclaimed sites and clea n streams. This result was most likely due to the spatially heterogeneous o ccurrence of many macroalgal taxa. Two taxa, Klebsormidium rivulare and Mic rospora tumidula, did appear to be useful assessors of intense AMD impact. A total of 40 infrageneric taxa were recorded with the greatest species ric hness occurring in the spring (27 taxa). Chlorophytes were the dominant gro up throughout the watershed with 19 species. Percent macroalgal cover of st ream reaches varied throughout the year within a single stream and among lo tic systems. Our results showed that numerous taxa were overlooked in the s easonal versus monthly sampling, but that sampling more streams on a less f requent basis compensated to provide a complete listing of taxa for the wat ershed. (C) 2001 Elsevier Science B.V. All rights reserved.