EFFECTS OF STREAM PH REGIME ON MACROINVERTEBRATE BIOMASS AND LEAF DECAY RATE IN HIGH AND LOW SOLUTE STREAMS IN LA SELVA, COSTA RICA
Freshwater stream ecosystem services can be altered by variation in their physicochemical parameters. In this study we examined the effects of pH on stream ecosystems in La Selva Biological Station, Costa Rica. Some streams receive high-solute groundwater inputs due to geothermal activity outside the watershed. As a result of increased bicarbonate concentrations, these streams have a naturally higher and more stable pH than neighboring low-solute streams that do not receive high-solute groundwater. To examine the effect of pH on stream ecosystem function, we used a sodium bicarbonate drip to experimentally increase the pH of a naturally low-solute stream to mimic the pH regime of a high-solute stream. The pH range of the manipulated site did not differ from that of the reference high-solute stream, while the reference low-solute stream had a significantly lower pH ranges. We quantified macroinvertebrate biomass from leaf packs in the treatment stream as well as low and high solute reference streams. Leaf decay increased with time but showed no correlation with pH. Macroinvertebrate biomass did not vary with pH. The results of this experiment indicate that factors other than pH are significant in influencing stream ecosystems.
Rupert England (Primary Presenter/Author,Co-Presenter/Co-Author), Alabama A&M University, email@example.com;
Carissa Ganong (Co-Presenter/Co-Author), Missouri Western State University, firstname.lastname@example.org;