Fresh Water Shrimp Recovery from
Poisoning related data sets
PROJECT DESCRIPTION
: Quebrada Sonadora was poisoned with chlorine bleach 140 m
upstream from the bridge of Road 186 in the LEF causing massive mortality of freshwater
shrimps over a ~500 m reach (300 m a.s.l. , Fig. 1). The poisoning was discovered
on 12 March 1999 and was estimated to have occurred on 10 March, based on the
state of decay of thousands of dead shrimps observed along the river. No carcasses
of Sicydium plumieri were observed. While no bleach bottles were found at the
site of this poisoning, bleach bottles have been found at other stream poisonings
documented in the LEF, and locals report that swimming pool tablets are also sometimes
used in illegal chlorine poisonings. Chlorine is known to display rapid volatilization,
transformation, and flushing in lotic waters; thus, LEF chlorine poisonings are
pulse disturbances. When the poisoning was discovered, the benthos in pools of
the poisoned reach was visibly and dramatically different than the pool benthos
upstream. In downstream pools, shrimps were not observed, and thick layers of
sediment and fine particulate organic matter (FPOM) coated the rocks. In pools
upstream from the poisoning, xiphocaridid and atyid shrimps were active, and no
visible sediment/FPOM was observed on rocks. In contrast, there were no pronounced
differences in sediment/FPOM accrual between riffles above and below the poisoning. These visual observations of immediate effects suggested that the poisoning event
represented a unique opportunity to quantify large-scale effects of shrimp removal
for comparison to previous small-scale manipulative experiments conducted in the
Sonadora and tributaries (Prieta, Toronja). In the first component of this project,
from March 26 to April 6, 1999, we quantified differences between the first 100
m of the poisoned reach and a 100-m reference reach immediately upstream from
the poisoned reach, and we conducted a manipulative experiment, adding freshwater
shrimps (Xiphocaris elongata, Atya lanipes, Macrobrachium spp. ) to 3 poisoned
pools for comparison to 3 poisoned pools in which no shrimps were added.
In the second component of this project, from June 15 to July 28, 1999, we
assessed recovery of the poisoned reach, comparing the upper 315 m of the poisoned
reach to a 250-m reference reach immediately upstream from the poisoning.
Created By: Eda C. Melendez-Colom
(emelend@lternet.edu
)
Last Modified On: April 29, 2005