Lophopodella capensis (Sollas, 1908) is only known from a limited number of palustrine and lacustrine sites in southern Africa and single sites in both Kenya and Israel. Statoblasts of L. capensis were found preserved in the Upper Pleistocene and Holocene aged sediments of Enapuiyapui wetland, Eastern Mau Forest, western Kenya. The wetland is a headwater microcatchment of tributaries that feed into the Mara River and the Lake Victoria Basin. Bryozoan taxa were not surveyed in a 2007 macroinvertebrate biodiversity assessment. The presence of L. capensis at this site marks the second observation of this taxon in Kenya, 65 km from Lake Naivasha, where observed prior, and in a location some 1000 meters higher. The results suggest Bryozoa should be included in aquatic biodiversity surveys that target these wetlands and that bryozoan remains should be incorporated into palaeoecological studies as useful palaeoenvironmental indicators.

Aquatic, biogeography, distribution, freshwater, fossil, statoblasts, subfossil, Mara River, palaeodistribution, palustrine, range

Lophopodella capensis (Sollas, 1908) (Bryozoa: Phylactolaemata: Lophopodidae) is a small Bryozoan that is epiphytic on stems and leaves and epilithic and occurs in freshwater to brackish waters, up to 9.4 pH in a temperature range of 18–25 °C (Lacourt 1968). It has been observed at water depths from littoral to 18 m depth (Lacourt 1967). L. capensis specimens were originally described from Vlei, Cape town, South Africa, in 1908 (collected in October 1907), and has since then been documented at other locations including Namibia in 1911 (Kraepelin 1914), multiple sites in the Transvaal since 1928 (Hastings 1929), Lake Naivasha, Kenya (Jenkin 1936), and more recently in the Golan Heights, Israel in 1967 (Massard and Geimer 1991). Additional reports of specimens from sites in Japan and UK, but, these have not been confirmed with certainty. The chitinous asexual buds (statoblasts) of Phylactolaemata preserve well within the geologic record of the Upper Quaternary and have potential for interpreting palaeoenvironmental conditions and examining the natural history of identifiable taxa (Francis 2001). Here we present a second occurrence of L. capensis in Kenya from subfossil statoblasts observed in the Upper Pleistocene and Holocene aged sediments of a small, montane wetland located in the Eastern Mau Forest.

Kiptunga Forest Block is located in the Eastern Mau Forest Block, Mau Narok County, Kenya, and is managed by a local Kenya Forest Service (KFS) station (Figure 1). The Eastern Mau Forest is the smallest of the Mau Forest blocks and has been identified as the most susceptible to negative impacts caused by anthropogenic land use, land cover, and global climatic changes, yet, has high potential for ecological restoration and recovery (Kinyanjui 2011). The region is situated upon the Mau Escarpment that forms part of the western face of the Great Rift Valley. The geology consists of undifferentiated Tertiary volcanic rocks overlain by Tertiary eutaxitic welded tuffs, which are evident in streambeds and occasional outcrops. The surficial geology consists of an extensive, thick mantle of Upper Pleistocene Mau ashes with basal tuffs (Jennings 1971, Williams 1991), possibly sourced from Londiani and/or Kilombe. Soils consist of relatively young and productive Udands (Andisols) due to the humid orographic climate modifying the abundant volcanic tephra. The mantling and subsequent aeolian and hydrological reworking of the tephra deposit may have formed much of the topographic relief of the ridge including the shallow basin where the wetland subsequently developed.

Figure 1. 

Location of the study site in Africa (A) and within Kenya (B). The location of the coring site (black circle) within Enapuiyapui (C). The red line represents a fire break cutline.

The indigenous forest is diverse with abundant Afromontane taxa including Croton, Dombeya, Ficus, Juniperus, Olea spp., Podocarpus, Polyscias, Prunus and Schefflera, of which, remnant scattered minor pockets remain. Most of the indigenous forest has been cut and converted to agroforests by the 1930s (Troup 1932) and the forest vegetation is currently partitioned into plantations with cyclic harvesting (Okeyo-Owuor 2007, Sanya 2008). Plantation taxa include indigenous Juniperus procera and, increasingly, exotic taxa are planted, which include Pinus patula, Cupressus lusitanica, Corymbia maculata (syn. Eucalyptus maculate; Sanya 2008, Courtney Mustaphi et al. 2014). Stresses on the plantation forests include pests, such as insects, rodents, monkeys that may damage the apical buds of Pinus and Cupressus, and fires during dry periods. Kiptunga Forest hosts wildlife populations of birds, antelopes, gazelles, hyrax, small reptiles, small primates and hyenas (Okeyo-Owuor 2007). A survey of macroinvertebrate taxa conducted in April 2007 found 606 families but did not observe any Phylactolaemata (Okeyo-Owuor 2007). The region is inhabited by the Ogiek community who are traditionally practiced hunter-gatherer livelihoods but current local populations are increasingly practicing pastoralism, dominantly cattle, goats and sheep, and much of the lower elevations have been converted to sedentary agriculture (Spruyt 2011).

The data reported in this paper have been deposited to the Harvard Dataverse repository (Courtney Mustaphi et al. 2016) at https://doi.org/10.7910/DVN/ONKLLL.

Neither Lophopodella capensis nor other Phylactolaemata taxa were encountered in a macroinvertebrate survey conducted across the swamp in April 2007 (Okeyo-Owuor 2007). Although, the survey does not explicitly state whether bryozoans were target taxa for surveying, nor are there details if they were observed or known to be absent. No macroscopic (>125 μm) bryozoan remains were observed in subsamples from the 19 surface sediment samples collected across the wetland. L. capensis were present in three clusters in the stratigraphy and suggest that L. capensis was present in the wetland since at least 15600 yr BP and was certainly present until recently, around 120 yr BP (Figure 4). Preservation was variable and suggests that degradation of chitinous material has varied throughout the ontogeny of the wetland (Figures 5–8). Presence data represent local presence of the taxa; yet, absence cannot be conclusively interpreted as absence of the taxa in the palaeoenvironment nor present. The historical presence of L. capensis at Enapuiyapui, a montane headwater wetland, suggests range and biogeography may be influenced by animal dispersal. Although not observed related to L. capensis, birds have been shown to be associated with the distributions of some freshwater bryozoans (Freeland et al. 2000; Figuerola et al. 2005). Possible pathways include feather and skin attachment and ingestion and subsequent excretion after traveling (Brochet et al. 2010). Since waterborne dispersal is possible by lophopodid taxa (Wood 2009), the ecological range may include parts of the Lake Victoria Basin and ultimately the Nile, at least during certain intervals of the Late Pleistocene and Holocene. Similar to other lophopodid, L. capensis may be adapted to seasonal drought or possibly extended, multi-year dry periods (Wood 2009). Unlike most other phylac species, the free statoblast of a related taxa, L. carteri, is initially non-buoyant and sinks through the water column, is deposited at the bottom of the basin, to be covered by sediments. During drought conditions, the water dries up and the statoblasts are protected from direct sunlight. As the statoblast dries the water in the large annulus is replaced by air, making the entire structure very buoyant once water returns. Once refloated to the water surface it can germinate within a few days. If a lake does not dry up the statoblast will still eventually germinate if the water-sediment interface temperature is sufficiently warm (Wood and Marsh 1996). This strategy could also be present in L. capensis but has yet to be confirmed. Observational or experimental work could further refine the ecological knowledge of this taxa and be beneficial for palaeoenviornmental intepretations of hydrological conditions. Like most phylactolaemates, living L. capensis colonies tolerate a water temperature range of 18–25 °C (Lacourt 1968), yet, dormant statoblasts can survive much wider extremes, which likely occur at this high elevation site.The relatively cool water at this high elevation, equatorial location suggests persistence at water temperatures below 18 °C. The inventory of tropical and African phylactolaemata fauna requires further investigation to understand distributions and the natural history of these taxa (Wood 2002).

Figures 5–8. 

Lophopodella capensis statoblasts and organic detritus, including charcoal at right, from the sieved sediment subsample from25–26 cm stratigraphic depth, dated to 220–230 yr BP (5). A well preserved statoblast observed at 41–42 cm, dated to 670–711 (6). Pleistocene-aged statoblast from 480–481 cm, dated to 15600–15700 (7). Same specimen as Fig. 6 showing the split layers of the polar spine and recurved hooks (8).

Additional radiocarbon dates of the sediment stratigraphy could further constrain the presence data of this taxon. We suggest that presence data of bryozoan macroremains, including the resistant chitinous statoblasts and floatoblasts be examined in other sedimentological studies in East Africa (Francis 2001) as they remain an infrequently used indicator of aquatic palaeoenvironments and the potential of this proxy is not being realised. In addition these results contribute to our knowledge of African Phylactolaemata natural history. The results of such palaeodistributions can be submitted and archived in palaeoecological databases such as Neotoma (Goring et al. 2015). The new finding also suggests that Phylactolaemata should be considered more centrally in biodiversity surveys of macroinvertebrates of Kenyan wetlands. New studies of African phylactolaemata are necessary to understand biodiversity loss, local indicators of water quality fluctuations, changes to ecosystem function and as part of developing and incorporating nature-based solutions into local-level land management plans.

We thank County Forest Coordinator Samuel Mukundi, forester Dennis K. Mbogo (retired), and KFS askari for permission and help accessing the wetland. We also thank three local men and volunteers from TimSales Ltd. for coring aid and Rebecca M. Muthoni for field work. We thank the British Institute in Eastern Africa (Nairobi) and the late Joseph Mutua for logistical support and acknowledge Denis Odera (NACOSTI) and Margaret Omoto (NMK) for help with research and export permits. Roland Gehrels graciously permitted use of microscope equipment and Henry Lamb aided with ITRAX, RGB, and magnetic susceptibility scanning. Maria Gehrels prepared the digital microscopy photographs. We thank Timothy S. Wood for his encouragement and guidance on the identification and distributions of L. capensis and for commenting on manuscript drafts. We also thank Professor Beth Okamura for her constructive review of this manuscript, which improved the clarity of the paper and advanced the discussion section. This research was funded by Resilience in East African Landscapes (REAL), a European Commission Marie Curie Initial Training Network grant to RM (FP7-PEOPLE-2013-ITN project number 606879).