| dc.description.abstract | Tayrona National Natural Park (TNNP) is a
hotspot of coral reef biodiversity in the Colombian
Caribbean, located between the city of Santa Marta
(>455,000 inhabitants) and several smaller river mouths
(Rio Piedras, Mendihuaca, Guachaca). The region also
experiences a strong seasonal variation in physical parameters
(temperature, salinity, wind, and water currents)
due to alternating dry seasons with coastal upwelling
and rainy seasons. However, the spatial and
temporal effects on water quality parameters relevant
for coral reef functioning have not been investigated.
Therefore, inorganic nutrient, chlorophyll a, and particulate
organic carbon (POC) concentrations along with
biological O2 demand (BOD), pH, and water clarity
directly above local coral reefs (~10 m water depth)
were monitored for 25 months in four bays along a
distance gradient (12–20 km) to Santa Marta in the
southwest and to the first river mouth (17–27 km) in
the east. This is by far the most comprehensive coral
reefs water quality dataset for the region. Findings revealed
that particularly during non-upwelling, chlorophyll
a and POC concentrations along with BOD significantly
increased with decreasing distance to the rivers
in the east, suggesting that the observed spatial water
quality decline was triggered by riverine runoff and not
by the countercurrent-located Santa Marta. Nitrate, nitrite,
and chlorophyll a concentrations significantly increased
during upwelling, while pH and water clarity
decreased. Generally, water quality in TNNP was close
to oligotrophic conditions adequate for coral reef growth
during non-upwelling, but exceeded critical threshold
values during upwelling and in relation to riverine
discharge. | |
