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Title:

Environmental Assessment of Ten Aquaculture
Sites in Rwanda, Africa


Author(s):

Deutsch, W.


Date: 1992


Funding Agency: USAID


Keywords: rwanda, environment, development, international, disease, effluent, aquaculture


Category: International Country Report


Download: Download


Summary/Recommendations/Objectives:

From August 6-17,
J990, an environmental assessment was conducted

at 10 potential
sites (in seven prefectures) for cooperatively

managed, integrated
aquaculture farms in the marais (wetland valleys)

of Rwanda. Sites
were evaluated for existing pond construction and

management practices,
and recommendations were made to minimize

the risk of
waterborne disease and other negative environmental

impacts.

Snail hosts for
schistosomiasis and sheep and cattle liver fluke

occurred at more than
half of the 10 ponds sampled. Mosquito larvae

were less common.
and anopheline mosquitos (vectors of malaria)

were found at only
one site. Most snails and mosquitos occurred at

poorly built and
managed ponds. The presence of a well-trained

extension agent at
a site was a critical factor to ensure well-managed

ponds and thus
reduce risk of waterborne disease.

Two supply canals
and three discharge canals were sampled for

rnacroinvertebrates
to determine possible downstream impacts of

fishponds. Benthic communities
were characterized by low biodiversity

and high tolerance
to organic enrichment, probably because of frequent

dredging of canals,
intermittent water flows and organic runoff

from human and livestock
activity. No negative environmental impact

directly attributable
to fish culture activity was detected.

At the scale and
management intensity of the proposed aquaculture

centers, fishponds would
have relatively low volume and infrequent

discharges that
should not cause undue environmental degradation

downstream.

Four streams with a
wide range of organic pollution were sampled for
macroinvertebrates to evaluate methods for a biomonitoring program. Use of a biotic index proved appropriate and practical for assessing
stream water quality in Rwanda. Protocols with field methods, data interpretation
tables, and a cumulative list of macroinvertebrate taxa

in Rwanda are
provided.

Risks of
indiscriminate introduction of non-native species to Rwanda

are discussed, and a
review and decision model for evaluating proposed

exotic fish introductions is presented

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