Date of Award
Tropical cloud forest streams are one of the most threatened and understudied ecosystems in the world. Understanding how these ecosystems function is essential for effective conservation. In this study, macroinvertebrate community composition, functional feeding group analysis, ecosystem attributes, and physicochemical parameters were used to evaluate biophysical stream conditions of 3 low-order Neotropical cloud forest streams at Reserva Las Gralarias in Mindo, Ecuador. Additionally, food web structure was analyzed via stable isotope analysis and aquatic insect emergence rate was also examined. As stream size increased from 1st to 3rd order, the macroinvertebrate communities shifted from being collector-gatherer dominated (65.2 to 29.8%, respectively) to being scraper dominated (17.9 to 56.3%, respectively). Shredders were poorly represented in all streams (2.7, 3.3, and 2.0% for 1st, 2nd, and 3rd order streams, respectively) similar to reports from other tropical systems. The analyses used in this and other tropical stream studies are based on temperate-based theories, which have been found to be inapplicable to tropical systems. Until tropical-based theoretical predictions are established, however, conservation efforts based on temperate theories should be implemented. Stable isotope analysis revealed a typical food web structure with basal resources having the lowest δ13C and δ15N signatures and these values increasing up the food web. Generally, δ15N signatures in our systems were depleted when compared to other tropical studies. Lastly, aquatic insect emergence was not correlated with rain or the moon cycle. Results from this study provide base-line physical, chemical, and biological data on these streams that can be effectively used to track environmental changes in land-use via long-term monitoring. Furthermore, results from this study provide basic data on tropical stream ecosystem function that will be valuable as stream theories with specific predictions for the tropics are created, which will lead to better 5 monitoring efforts and more effective restoration and protection of these threatened and disappearing systems.
Harris, Anna M., "Macroinvertebrate Community Composition, Food Web Structure, and Emergence Rate in Neotropical Cloud-Forest Streams in Mindo, Ecuador" (2016). Masters Theses. 823.