Taxa occurrence (presence/absence) and composition of benthic macroinvertebrates from trawl surveys (2003-2017) conducted on Lake Victoria, Uganda

Study Extent

The datasets present data for trawl surveys conducted between 2003 and 2017. However, not all transects or years may be represented in the sample as depending on resources, sampling may not take place in some years or transects.

Sampling

A Ponar grab (with open jaw area, 238cm2) was used to take sediment samples for analysis of benthic macroinvertebrates. Three spread hauls were taken from each sampling point. The bottom type at each point was described from the grabbed contents. Each of the three samples (hauls) from each area was then concentrated placed in labeled sample bottles, and preserved with 5% formalin solution and taken for laboratory analysis. In the laboratory, each sample was rinsed with water to remove the formalin and then placed on a white flat-bottomed tray. Using pair of forceps all macro-invertebrates were sorted from the sediment and the individual taxa identified to the lowest possible taxonomic level using identification manuals and a dissecting binocular microscope at 4 x 25 magnification. All taxa from the different hauls were recorded and individuals of each taxon enumerated to estimate their densities from which the following results were generated. The taxa were identified using taxonomic keys by Mandahl-Barth (1954), Pennak (1953), and Merritt and Cummins (1997). De Moor et al. (2003).

Quality Control

The samples were immediately processed in the field and treated with formalin to keep the organisms of interest intact and prevent them from rotting. To avoid loss of organisms during sample processing, appropriate mesh sizes were used.

Method steps

1. Collection of the macroinvertebrates In the field, sediment samples were collected using a ponar grab with an open jaw surface area of 238 cm2. At each site, three sediment samples were obtained. The three samples were mixed and concentrated to form one composite sample for each site. Preserving the samples The composite sample for each site was separately preserved in 5% formalin to maintain the organisms in good condition prior to analysis in the laboratory. Identification of macroinvertebrates In the laboratory, formalin was rinsed off from each sample and placed in white flat-bottomed trays. Using pairs of forceps, all benthic macro invertebrates were sorted from the sediment and the individual taxa identified to the lowest possible taxonomic level using appropriate identification keys and a dissecting binocular microscope at x 25 magnification.

This dataset covers aquatic macro-invertebrates

1. Povilla adusta
   rank: species
2. Ablabesmyia
   rank: genus
3. Aeschenidae
   rank: family
4. Aspatheria
   rank: genus
5. Bellamya unicolor
   rank: species
6. Bulinus
   rank: genus
7. Byssanodonta parasitica
   rank: species
8. Caelatura
   rank: genus
9. Caelatura alluaudi
   rank: species
10. Caelatura hauttecoeuri
    rank: species
11. Caelatura monceti
    rank: species
12. Caenis
    rank: genus
13. Caridina nilotica
    rank: species
14. Chaoborus
    rank: genus
15. Chironomus
    rank: genus
16. Clinotanypus
    rank: genus
17. Corbicula africana
    rank: species
18. Cryptochironomus
    rank: genus
19. Economidae
    rank: family
20. Ephemeridae
    rank: family
21. Gabbia humerosa
    rank: species
22. Gomphidae
    rank: family
23. Hirudinea
    rank: class
24. Leptoceridae
    rank: family
25. Libellulidae
    rank: family
26. Melanoides tuberculata
    rank: species
27. Mutela bourguignati
    rank: species
28. Oligochaeta
    rank: class
29. Ostracoda
    rank: class
30. Philopotamidae
    rank: family
31. Pisidium
    rank: genus
32. Povilla adusta
    rank: species
33. Procladius
    rank: genus
34. Pseudoneureclipsis
    rank: genus
35. Sphaerium
    rank: genus
36. Tanypus
    rank: genus
37. Tanytarsus
    rank: genus

The dataset covers Lake Victoria, Uganda.