Synopsis of the distribution of Macroalgae in Tanzania along the western part of the Indian Ocean

The dataset consists of forty-three families of the Phylums, Chlorophyta (12), Ochrophyta (7) and Rhodophyta (24). In the Chlorophyta, the dominating families are Caulerpaceae, Halimedaceae, and Cladophoraceae. Caulerpaceae are macroscopic with a horizontal creeping main branch, produce bunches of rhizoids on the underside and erect shoots on the upper side. Traditionally they have been used as food and medicine in Southeast and East Asia, and there are also records of using these seaweeds as medicine and fish bait in Tanzania. For members of the Halimedaceae, the thallus looks like an articulate series of branches made up of green, disk-like segments that are rigid due to the deposition of lime (calcium carbonate) and the central edible part eaten by most herbivores. Members of this family, for instance, Halimeda segment substratum in Chwaka Bay, Pangamkungu, Mjini Kiuyu, Unguja and Pemba Islands, are ecologically important as their calcified segments form a substratum, supporting the growth of other macroalgae and seagrasses. Also, recent findings show that the family contributes to the higher productivity of seagrasses and carbon sequestration. The Cladophoraceae have thalli that form prostrate cushions, erect tufts of a branch, or unbranched free filaments. Species of this family are important food for fish and other aquatic organisms. In the Phylum Ochrophyta, Dictyotaceae and Sargassaceae dominated different sampling locations. Dictyotaceae have narrow, ribbon-shaped branched thalli, with a conspicuous midrib, lateral veins in some species, growth from a group of small apical cells, except the midrib. They occur in warmer waters more than any other brown algae, and some members, e.g. Dictyota adnata and D. bartayresiana used as a drug, larvicide, fodder, fish meal, and manure. The Sargassaceae, generally found in warmer waters, are brown or dark green, have large thalli, are well-branched, and have air bladders. They may grow to several metres and are home to different aquatic organisms such as crabs, snails, sea turtles and fish. They are nutritious and a rich source of bioactive compounds such as vitamins, carotenoids, dietary fibres, proteins and minerals. Species of this family are also sources of the commercially important phycocolloids in the group of alginates. The Phylum Rhodophyta consists of the Rhodomelaceae, Gracilariaceae, Solieriaceae and Galaxauraceae. Rhodomelaceae contain the largest genera of the collected seaweed in the herbarium. They have thallus structures with polysiphonous, and in cross-section, the thallus appears to consist of a series of siphons. The segments originating from the transverse divisions of the apical cell from the central axis, the cells of the significant axis remain attached by conspicuous pit connections and the primary cells derived from the apical cell divide periclinal producing four or five pericentral cells. The Gracilariaceae consists of important agarophytes such as Gracilaria and Gracilariopsis. They inhabit temperate and tropical seawater, and their thalli are macroscopic, solid and completely cellular, without free filaments in the cortex or medulla. The Solieriaceae have thalli which are cylindrical to flattened, well-branched, structure multiaxial with a clear filamentous medulla, which may also contain a core of densely packed cells.

1. Rhodophyta
   rank: phylum
2. Chlorophyta
   rank: phylum
3. Ochrophyta
   rank: phylum

This Macroalgae dataset consists of specimens' records mainly from the rocky shore of the Western part of the Indian Ocean, primarily the Tanga, Dar es Salaam, Coast and Lindi regions, and the Islands of Unguja and Pemba. The areas lie in between latitude -4.94769 and -9.98761, and Longitude 38. 97594 and 39.78730. Records from North America are from Botany Beach, Pt. Aransas, Texas, Suva Pt, Fuji, Warden's creek between the Latitude -34.00944 and 40.06621, and the Longitude 38.9759 and 39.87730.