Lake Opeta

UGATIPA29
Lake Opeta

Country: Uganda

Administrative region: Eastern (Region)

Central co-ordinates: 1.60077 N, 34.19305 E

Area: 689.12km²

Qualifying IPA Criteria

C(iii)Site contains nationally threatened or restricted habitat or vegetation types, AND/OR habitats that have severely declined in extent nationally

IPA assessment rationale

Lake Opeta qualifies as an IPA under sub-criterion C(iii) as one of the five best sites for nationally Vulnerable habitat freshwater marsh (VU). Encompassing 7.9% of the national resource, this IPA is possibly the largest extent of freshwater marsh national that could be managed as a single site. As freshwater wetlands become more threatened nationally, it is important to conserve the marshes at this site, particularly to preserve the many important ecosystems services they provide.

Site description

Lake Opeta IPA is one of the most important wetlands nationally. The lake and its surrounding habitats are situated in the Kyoga Basin in northeastern Uganda, in the districts of Nakapiripirit, Sironko, Katakwi and Kumi and is located 25 km north-west from Kumi town. The IPA boundary is based on that of Lake Opeta Wetland System Ramsar site, while the northern part of this IPA overlaps with Pian-Upe Wildlife Reserve. The main inflow into the Opeta system is through River Sironko (Kasangaki 2009).

Botanical significance

Lake Opeta is one of the most important areas of freshwater marsh, a nationally Vulnerable habitat type, in Uganda. Encompassing 8% of the national resource (Richards et al. 2024), this IPA is likely the largest extent of freshwater marsh that can be managed as a single site. Wetlands are under significant pressure nationally and are estimated to have declined from 17.5% national coverage in the 1990s to 8.5% by 2021 (Wambede 2021). Several wetlands in Uganda have been heavily degraded due to agricultural encroachment, rice farming in particular, that result from land shortages (Bunyangha et al. 2022). Loss of ecosystem services has been linked to this encroachment, for instance around Mpologoma wetlands degradation has been linked to increased flooding locally (Wambede 2021). The Lake Opeta landscape also provides important habitat for Uganda’s only endemic bird species, Fox’s Weaver (Ploceus spekeoides). Conservation of the Lake Opeta Freshwater Marshes is, therefore, of great importance in order to avoid the loss of the numerous crucial ecosystem services provided by wetland habitats (see Key ecosystem services).

There is no IPA trigger species in Lake Opeta wetland system, however, further surveys may well reveal species of interest.

Habitat and geology

The main vegetation type of the general landscape in this area is Acacia - Hyparrhenia - Themeda grass savannah (Langdale-Brown et al. 1964). Lake Opeta wetland system lies on flat terrain and is predominantly an extensive marsh of Echinochloa pryamidalis and Vossia cuspidata surrounding the open water of the lake to the east and south graduating into dry Hyparrhenia grassland savannas. The swamp has Lake Opeta most of which is covered by Nymphea nouchali var. caerulea with Najas pectinata and Ceratophyllum dumersum and surrounded by a thin fringe or small pockets of Cyperus papyrus to the eastern side and patches of Miscanthus and Typha (Byaruhanga & Kigoolo 2005, Kalema 2005, Odull & Byaruhanga 2009). The marshy areas are fringed by seasonally flooded communities of impeded drainage with Panicum repens, Sporobolus pyramidalis, Cyperus articulatus C. denudatus and Cynodon dactylon (Kalema 2005). The drier land patches are composed of thicket and bushland communities of Euphorbia candelabrum, Grewia villosa in mixture with species of Acacia, Ziziphus, Combretum and Harrisonia.

In the centre of the IPA is Tisai Island, which is occupied by a small community of people. As a result, this area is largely transformed to arable agriculture (Google Earth 2023).

The climate of Lake Opeta wetland system is tropical in nature and is influenced by the air currents such as the southeast and northeast monsoons. The system has a rainy and dry season. The area generally experiences a uni-modal low rainfall which comes in the long, wet season of April to October, in contrast to the bimodal pattern of the south and west of Uganda (State of Environment Report, 1998). Rainfall is erratic, variable and highly localized, ranging from 500 – 1,000 mm with a mean annual figure of between 500 to 700 mm. Mean annual minimum temperatures range from 15 to 17.50 C and mean maximum temperature from 30 - 32.50 C.

Lake Opeta wetland system is underlain by a mixture of Pre-Cambrianand Cenozoic rocks of Pleistocene to recent (NEMA 2009). The rock types comprise the banded gneisses of Aruan tectonic Age (Byaruganga & Kigoloo 2005).

Conservation issues

Lake Opeta Wetland is both an Important Bird Area (IBA) and a Ramsar Site (Odull & Byaruhanga 2009). NatureUganda has been promoting conservation of Lake Opeta as a potential tourism destination, and also prioritizing it for conservation because of its importance for survival of the Near Threatened Fox’s Weaver, Uganda’s only endemic bird (Byaruhanga & Kigolo 2005). This site is also of note for the presence of a Vulnerable cichlid fish, Paralabidochromis plagiodon, which is restricted to lakeshores of Lake Victoria, Kyoga and Opeta (FishBase 2024; Morris 2024).

NatureUganda has also been lobbying the relevant institutions to upgrade the conservation status of the area while the Wetland Management Department undertakes education and awareness activities in the area.

There is often overstocking of cattle grazing in the wetlands during dry seasons, which may have a long-term impact on the ecology and character of the area. Fishing occurs on the lake which results into cutting of trees for smoking the fish, as well as charcoal burning (Kalema 2005). River Sironko which drains into the Lake Opeta system, is highly turbid from agricultural activities upstream (Kasangaki 2009), which may well impact the quality of the freshwater marshes at this site.

Ecosystem services

Several important hydrological ecosystem services are provided by Lake Opeta and its wetlands. These include water storage, flood control, ground water recharge, sediment retention and water purification (Byaruhanga & Kigolo 2005). During the dry season, the wetlands provide a continuous discharge of water, maintaining water availability in the surrounding areas. The Lake Opeta area is used by the Iteso, Karimojong and the Pokot peoples for dry season grazing and watering of animals (Byaruhanga & Kigolo 2005). There is also a wooded island in the middle of the swamp called the Tisai which a small community occupies (Byaruhanga & Kigolo, 2005).

Alongside provision and regulation of hydrological services, parts of the site have been identified as a “probable peatland” in a national analysis of peat deposits (Elshehawi et al. 2019). If peat does underlie areas of this IPA, it would highlight its importance as a carbon store (although the wetland habitats likely store large amounts of carbon in any case).

Lake Opeta provides food, particularly a valuable source of protein, and livelihoods through fishing activities, with two landing sites on the lake (NaFIRRI 2008). It is likely that the freshwater marshes provide important nursery habitats for fish species at the site, including fish for catch and the threatened and restricted cichlid, Paralabidochromis plagiodon (VU).

Site assessor(s)

Samuel Ojelel, Makerere University Herbarium

Sophie Richards, Royal Botanic Gardens, Kew

James Kalema, Makerere University Herbarium

IPA criterion C qualifying habitats

Habitat Qualifying sub-criterion ≥ 5% of national resource ≥ 10% of national resource 1 of 5 best sites nationally Areal coverage at site
Freshwater marshes (VU) C(iii) True False True 374.1

Freshwater marshes (VU)

Qualifying sub-criterion:
C(iii)
≥ 5% of national resource:
True
≥ 10% of national resource:
False
Areal coverage at site:
374.1

General site habitats

General site habitat Percent coverage Importance
Wetlands (inland) - Bogs, Marshes, Swamps, Fens, Peatlands [generally over 8 ha] No value Major
Wetlands (inland) - Permanent Freshwater Lakes [over 8 ha] No value Major
Artificial - Terrestrial - Arable Land No value Major
Savanna - Dry Savanna No value Minor
Grassland - Subtropical/Tropical Seasonally Wet/Flooded Lowland Grassland No value Major

Wetlands (inland) - Bogs, Marshes, Swamps, Fens, Peatlands [generally over 8 ha]

Percent coverage:
No value
Importance:
Major

Wetlands (inland) - Permanent Freshwater Lakes [over 8 ha]

Percent coverage:
No value
Importance:
Major

Artificial - Terrestrial - Arable Land

Percent coverage:
No value
Importance:
Major

Savanna - Dry Savanna

Percent coverage:
No value
Importance:
Minor

Grassland - Subtropical/Tropical Seasonally Wet/Flooded Lowland Grassland

Percent coverage:
No value
Importance:
Major

Land use types

Land use type Percent coverage Importance
Nature conservation No value Major
Agriculture (arable) No value Major
Agriculture (pastoral) No value Major
Agriculture (aquatic) No value Major

Nature conservation

Percent coverage:
No value
Importance:
Major

Agriculture (arable)

Percent coverage:
No value
Importance:
Major

Agriculture (pastoral)

Percent coverage:
No value
Importance:
Major

Agriculture (aquatic)

Percent coverage:
No value
Importance:
Major

Threats

Threat Severity Timing
Residential & commercial development - Housing & urban areas Medium Ongoing - stable
Agriculture & aquaculture - Annual & perennial non-timber crops - Small-holder farming Medium Ongoing - stable
Agriculture & aquaculture - Livestock farming & ranching - Small-holder grazing, ranching or farming Medium Ongoing - trend unknown
Agriculture & aquaculture - Marine & freshwater aquaculture - Subsistence/artisinal aquaculture Unknown Ongoing - trend unknown
Biological resource use - Logging & wood harvesting Low Ongoing - trend unknown

Residential & commercial development - Housing & urban areas

Severity:
Medium
Timing:
Ongoing - stable

Agriculture & aquaculture - Annual & perennial non-timber crops - Small-holder farming

Severity:
Medium
Timing:
Ongoing - stable

Agriculture & aquaculture - Livestock farming & ranching - Small-holder grazing, ranching or farming

Severity:
Medium
Timing:
Ongoing - trend unknown

Agriculture & aquaculture - Marine & freshwater aquaculture - Subsistence/artisinal aquaculture

Severity:
Unknown
Timing:
Ongoing - trend unknown

Biological resource use - Logging & wood harvesting

Severity:
Low
Timing:
Ongoing - trend unknown

Protected areas

Protected area name Protected area type Relationship with IPA Areal overlap
Lake Opeta Wetland System Ramsar site protected/conservation area matches IPA 689
Pian Upe Wildlife Reserve protected/conservation area overlaps with IPA 76

Lake Opeta Wetland System

Protected area type:
Ramsar site
Relationship with IPA:
protected/conservation area matches IPA
Areal overlap:
689

Pian Upe

Protected area type:
Wildlife Reserve
Relationship with IPA:
protected/conservation area overlaps with IPA
Areal overlap:
76

Conservation designation

Designation name Protected area Relationship with IPA Areal overlap
Lake Opeta Important Bird Area protected/conservation area matches IPA 689
Lake Opeta Key Biodiversity Area protected/conservation area matches IPA 689

Lake Opeta

Protected area:
Important Bird Area
Relationship with IPA:
protected/conservation area matches IPA
Areal overlap:
689

Lake Opeta

Protected area:
Key Biodiversity Area
Relationship with IPA:
protected/conservation area matches IPA
Areal overlap:
689

Bibliography

, 2019

Google Earth

Satellite Imagery Available online

Elshehawi, S., Barthelmes, A., Beer, F., & Joosten, H., 2019

Assessment of Carbon (CO2) emissions avoidance potential from the Nile Basin peatlands

Langdale-Brown, I., Osmaston, H. A., & Wilson, J. G., 1964

The Vegetation of Uganda and its Bearing on Land-Use

Byaruhanga, A. & Kigoolo, S., 2005

Lake Opeta Wetland System Ramsar Information Sheet

Bunyangha, J., Muthumbi, A. W. N., Egeru, A., Asiimwe, R., Ulwodi, D. W., Gichuki, N. N. & Majaliwa, M. J. G., 2022

Preferred Attributes for Sustainable Wetland Management in Mpologoma Catchment, Uganda: A Discrete Choice Experiment

Land, Vol 11 Available online

Wambede, F., 2021

How human activities have destroyed Mpologoma wetland

Daily Monitor Available online

BirdLife International, 2017

Ploceus spekeoides. The IUCN Red List of Threatened Species 2017: e.T22718933A118849332.

FishBase, 2024

Haplochromis plagiodon

Available online

Kalema, J., 2005

Diversity and distribution of vascular plants in wetland and savanna Important Bird Areas of Uganda.

Kasangaki, E., 2009

Water quality assessments in the Opeta-Bisina wetland systems and Mburo-Nakivale wetland systems. A report to NatureUganda.

Harvard University M, Morris, P. J., 2024

Occurrence dataset https://doi.org/10.15468/p5rupv, Museum of Comparative Zoology, Harvard University. Version 162.441

Available online

Odull, O., M. & Byaruhanga, A., 2009

Ecological baseline survey of Lake Opeta-Bisina wetland system Lake Mburo-Nakivali wetland system

Available online

NaFIRRI, 2008

Report of Frame Survey of the Kyoga Basin Lakes 2008.

Available online

NEMA, 2009

Uganda: Atlas of Our Changing Environment

Available online

Recommended citation

Samuel Ojelel, Sophie Richards, James Kalema (2024) Tropical Important Plant Areas Explorer: Lake Opeta (Uganda). https://tipas.kew.org/site/lake-opeta/ (Accessed on 07/11/2024)