A Limnological Investigation of a Tropical Fresh-Water Ecosystem: The Belize River, Belize, Central America
Date of Award
Doctor of Philosophy
Dr. Clarence J. Goodnight
Dr. George G. Mallinson
Dr. Richard W. Pippen
Dr. Dale Warren
The limnology of the Belize River, from the region of Spanish Lookout to the region of Belize City, was investigated from 1977 through 1979. The investigation was done primarily during the months of May through August, covering the two seasonal changes--wet and dry--that occur in this tropical region. The investigation sought to describe various parameters of the Belize River so as to gain an understanding of this tropical fresh-water ecosystem and to provide basic information needed for the development of management programs.
Water samples were collected from eight stations and analyzed for acidity, alkalinity, carbon dioxide, chloride, sodium chromate, hexavalent chromium, copper, fluoride, calcium hardness, total hardness, hydrogen sulfide, iron (ferrous), manganese, nitrate, nitrite, dissolved oxygen, pH, orthophosphate, metaphosphate, silica, and sulfate. The river in general appeared to be slightly alkaline and aerobic except for the region near Belize City. Here the river was slightly acidic and less oxygenated. Seasonal changes were observed, such as higher dry-season alkalinity levels. Such changes could have been attributed to agricultural runoff and a dilution effect caused by flood conditions. The levels of most metal ions and cations were not sufficiently great to cause concern. Sufficient nutrients were available to support diversified planktonic, nektonic, and benthic populations.
The benthic fauna was sampled at six stations along the Belize River. The data collected reflect a great diversity in the taxonomic families present. Several insect orders were found, with Ephemeroptera, Diptera, and Tricoptera being predominant. Gastropods were also observed to be prevalent. The insect orders, Plecoptera and Neuroptera, were the least abundant forms of benthic organisms gathered.
The phytoplankton community of the river varied in both abundance and distribution. Members of the Cyanophyta phylum were noted to be dominant in the region near Belize City. Chlorophyta and Chrysophyta were more prevalent farther up-river. The zooplankton community was comprised of four major groups: Protista, Rotifera, Cladocera, and Copepoda. Of these, Protista were most prevalent at Stations 1 and 2 and Rotifera were more prevalent at the other six stations.
Because of the excessive discharge of organic effluents into the Belize River near Belize City, extremely high counts of total bacteria, total coliform, and yeast/mold were observed in this region. Farther up-river the counts were considerably less, but there were slight increases in colonies around areas of agricultural and livestock activity.
The qualitative data collected on the nektonic life of the Belize River revealed that a diverse community of freshwater fish occur in the river above the region of the city. Around Belize City, where the river meets the sea, intrusion of salt-water species contributed to the diversity observed. Several accounts of intrusion of salt-water fishes farther up-river were also reported.
It is evident from the data gathered that the region of the Belize River around Stations 1 and 2 is polluted. At the other stations, the water quality is generally of a high quality. However, levels of manganese, carbon dioxide, and alkalinity at a few stations were higher than those considered acceptable. Bacterial counts showed slight increases in regions where human and livestock activity occurred.
Gonzalez, Victor J., "A Limnological Investigation of a Tropical Fresh-Water Ecosystem: The Belize River, Belize, Central America" (1980). Dissertations. 2642.