Schematic diagram of the Rio Espiritu Santo, Puerto Rico, illustrating
observed and potential downstream-upstream effects. Barriers, both
natural (waterfalls) and artificial (dams and associated water abstraction),
act as selective filters along the stream continuum. Superimposed
on the upstream legacies created by these filters are the legacies created
by interactive effects of both natural (e.g., hurricanes and droughts)
and artificial (stream poisoning events, fishing, shrimp trapping, pollution)
disturbances [figure 5 from JNABS 16 (2): 425-438].