Mangroves are one of the most important ecosystems especially due to the services they provide, but in contrast are one of the most threatened by human activities at a global level. In Ecuador, mangrove forests are currently fragile and threatened due to the great anthropic pressure, which has largely reduced the area they occupy. However, there is already evidence that certain actions are contributing both to their conservation and the recovery of the lost mangrove area. In this study, we assessed the multitemporal dynamics of changes in mangrove cover in four coastal provinces of the country over a period of 20 years (1998–2018) based on remote sensing data analyzed using GIS tools. Our results showed that the area affected by mangrove forest destruction reached its maximum during the 1998–2010 period, when 4.56% (194.57 km²) of the mangrove forest was lost. This situation especially affected the provinces of El Oro and Guayas. The main cause for the loss of mangrove cover was the expansion of shrimp farms, followed by agriculture and construction. However, a slight recovery of ~2.9% has been observed, although loss remains constant. Mangrove ecosystem conservation policies, mainly applied to zones within protected areas; the establishment of use and custody agreements and the halt of shrimp farm expansion; the development of mangrove forests on areas with sediment deposits; and natural mangrove recovery processes are key factors for mangrove restoration. These results suggest that it is possible to continue restoring mangrove cover and thus maintain some of the main ecosystem services they provide for the benefit of humans.

Aquatic and rheophilous bryophytes can indicate water pollution as they bioaccumulate toxic water elements. We evaluated (1) bioaccumulation of eight heavy metals and arsenic by Marchantia polymorpha L., and (2) changes in bryophyte community structure, as responses to urban pollution in southern Ecuador. To this end, we registered presence/absence and coverage of submerged bryophytes in 120 quadrats across three zones of the Zamora river inside Loja city, and a control zone in a nearby forest. We found that the concentrations of five (Al, Cd, Cu, Fe, and Zn) of the eight chemical elements and arsenic were highest in urban M. polymorpha. Moreover, bryophyte species richness decreased in urban zones. Bryophyte community structure also differed between control and city zones, but no differences were found among city zones. The control zone was composed by a more distinct set of bryophyte species, e.g., an indicator species analysis showed that 16 species had high and significant indicator values for control zone, but only 11 species were indicators of at least one of the three urban zones. We concluded that bryophytes, in general, and M. polymorpha, in particular, can be suitable biomonitors of water quality in tropical urban rivers.

Water contamination is a major environmental problem in many cities of the world. Most water contamination results from industry and human activities that generate toxic substances (e.g., metals). Rheophilic and aquatic mosses are found in lotic ecosystems, and their morphological and physiological traits are responsive to ecological and pollution gradients. Here we hypothesized that the native rheophilic moss Platyhypnidium aquaticum (A. Jaeger) M. Fleisch exposed to polluted waters can bioaccumulate greater amounts of metals, and a metalloid, than P. aquaticum exposed to pollution-free water. To this aim, we tested the bioindicator capacity of the aquatic P. aquaticum for 15 metals (Cd, Pb, Zn, Fe, K, Ca, Na, Mn, V, Co, Ba, Cr, Al, Sr, and Mg) and one metalloid (As), in twelve river samples coming from three urban and one control zone along the Zamora river in the city of Loja. When compared to the control, our results showed that P. aquaticum in the Southern, Central, and Northern zones of the city bioaccumulated higher concentrations of Ba, Cd, Co, Fe, Mg, Mn, Na, Sr, Zn, and the metalloid As. On the other hand, concentrations of Al, Ca, Cr, Pb, and V in P. aquaticum tended to be lower in the control zone, but these differences were not significant. We suggest that the presence of these contaminants may be related to water pollution (e.g., residual discharges and a lack of treatment systems) along urban zones of the river. We report for the first time the utility of P. aquaticum as a model species for development of long-term biomonitoring programs of water contamination in South America. Passive biomonitoring with P. aquaticum can be a simple and low-cost method to obtain reliable data of the current state of water contamination with metals and metalloids in tropical regions.