Data from: Leaf-litter decomposition and macroinvertebrate assemblages along an urban stream gradient in Puerto Rico

Urbanization is a major land use form that has large impacts on
ecosystems. Urban development in the watershed impacts stream ecosystems
by increasing nutrient and organic matter loads, altering hydrology, and
reducing biodiversity. Puerto Rico is an ideal location to assess and
monitor the effects of urbanization on streams, because it is increasingly
urbanized and streams do not receive inputs of untreated sewage,
characteristic of many other tropical urban areas. The objective of this
study was to determine how leaf-litter decomposition and aquatic
macroinvertebrate assemblages varied along a tropical urban gradient. We
conducted the study in the Río Piedras watershed, San Juan Metropolitan
Area, in six low order streams that formed an urban gradient ranging from
10 to 70% urban land cover. At each stream, we placed six 5g leaf bags of
Ficus longifolia in three different pools and collected one bag on each
sampling date. Decomposition rates were fast in forested streams (range
0.021 – 0.039 day-1) and decreased with increasing urbanization (range
0.007 – 0.008 day-1). Rates were strongly and negatively correlated with
percent impervious surface cover (R= 0.81, p=0.01). Functional feeding
group diversity was higher in forested streams, with the presence of
shredders. Decomposition rates were significantly and positively
correlated with functional feeding group diversity and abundance (R= 0.66,
p= 0.04). Overall, our results show that urbanization affected the
environment and macroinvertebrate diversity resulting in large negative
effects on stream ecosystem function.