Leaf production, shoot demography, and flowering of the seagrass Thalassodendron ciliatum (Cymodoceaceae) along the East African coast
Kamermans, P.; Hemminga, M.A.; Marba, N.; Mateo, M.A.; Mtolera, M.; Stapel, J. (2001). Leaf production, shoot demography, and flowering of the seagrass Thalassodendron ciliatum (Cymodoceaceae) along the East African coast. Aquat. Bot. 70(3): 23 In: Aquatic Botany. Elsevier Science: Tokyo; Oxford; New York; London; Amsterdam. ISSN 0304-3770; e-ISSN 1879-1522, more |   |
| Keywords | Flora > Weeds > Marine organisms > Seaweeds > Sea grass
Reproduction
Thalassodendron ciliatum (Forsskål) Hartog, 1970 [WoRMS]
ISW, Kenya, Coast, Diani; ISW, Kenya, Coast, Kenyatta; ISW, Kenya, Coast, Nyali [Marine Regions]; ISW, Kenya, Coast, Roka; ISW, Kenya, Coast, Watamu; ISW, Kenyan Coast [Marine Regions]; ISW, Tanzania, Zanzibar [Marine Regions]
Marine/Coastal |
| Abstract | Several characteristics of Thalassodendron ciliatum populations were evaluated along the coasts of Kenya and Zanzibar Island, with the aim to study spatial variability in this species. The study is the first large-scale sampling effort to evaluate the status of T. ciliatum on the East African coast and provides a base line in future works. A reconstruction technique, which makes use of scars left by abscised leaves and flowers, was employed to determine leaf production, shoot demography and flowering frequency. Eight subtidal sites in different back-reef lagoons were sampled. Furthermore, samples were collected at a subtidal site that was not protected by a reef, a site with intertidal rock pools, and a subtidal site in a mangrove bay. Leaf-production rates were lowest for the T. ciliatum population of the subtidal site that was not protected by a reef and for the population from the intertidal rock pools (30 leaves shoot-1 year-1). At these sites, leaf lifespan was almost twice as long (94 days). Low leaf-formation rates seem to be compensated by long leaf lifespans to maintain similar numbers of standing leaves per shoot. Highest leaf-production rates were found at the mangrove-bay site (53 leaves shoot-1 year-1). The mangrove-bay population showed internodal lengths of almost 7 mm and stem lengths of almost 90 cm. The stems were two to four fold longer than those at the other sites. A short leaf lifespan of 51 days at the mangrove site indicates that the investment in stem growth occurs at the expense of leaf maintenance. Median ages of the populations varied almost four fold from 0.5 year to 1.8 years. Shoot recruitment and mortality rates differed significantly among sites. Differences could not be related to habitat type. All meadows in the present study were either expanding or in steady state. This suggests that, even though some sites were located near accumulations of beach hotels, the environmental quality in this region is still suitable for sustaining vigorous seagrass vegetation. Flowering frequencies were generally low. In addition, seedlings were not found in our study. Thus, sexual reproduction is of minor importance for the permanently submerged T. ciliatum populations, which reduces the ability to adapt to changes. |
| Dataset | - Kamermans P., Soetaert K. 1998: Leaf production, shoot demography, and flowering of the seagrass Thalassodendron ciliatum (Cymodoceaceae) along the East African coast. Netherlands Institute of Ecology; Centre for Estuarine and Marine Ecology, Netherlands. Metadata available at http://mda.nioo.knaw.nl/imis.php?module=dataset&dasid=1183, more
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