IMIS | Flanders Marine Institute

Flanders Marine Institute

Platform for marine research


Publications | Institutes | Persons | Datasets | Projects | Maps
[ report an error in this record ] Print this page

Groundwater effects on diversity and abundance of lagoonal seagrasses in Kenya and on Zanzibar Island (East Africa)
Kamermans P., Soetaert K. 1998:Groundwater effects on diversity and abundance of lagoonal seagrasses in Kenya and on Zanzibar Island (East Africa). Netherlands Institute of Ecology; Centre for Estuarine and Marine Ecology, Netherlands. Metadata available at

Archived data

Archived file:
Availability: Restricted
The data are withheld from general circulation and disclosure but access may be obtained on a case-by-case basis through negotiation

Notes: Restrictions available at contact person

Seagrass species diversity and abundance were studied in East African back-reef lagoons with contrasting groundwater-outflow rates. The selection of the lagoons was based on a groundwater flow model. more

A total of ten seagrass species was observed at all sites together. Sites with a higher groundwater outflow displayed a lower species diversity than sites with a lower groundwater outflow. Thalassodendron ciliatum dominated at sites with high groundwater outflow rates, while Thalssia hemprichii showed higher coverage at sites with low groundwater outflow. Porewater salinities were significantly lower at locations with high groundwater-outflow rates indicating supply of freshwater. Nitrogen stable isotope signatures of seagrass leaves showed a significant increase with increased groundwater-outflow rates. This suggests that the nitrogen source for these plants was, at least for a part, groundwater. In addition, lagoons with high densities of the human population had highest 15N values, indicative of anthropogenic nitrogen inputs. Differences in optimum salinity for growth between species and competition for nitrogen may explain the observed pattern in species diversity and abundance.

Biology, Biology > Plants, Geology - Geophysics - Sedimentation, Geology - Geophysics - Sedimentation > In-situ (near) seafloor data, Geology - Geophysics - Sedimentation > Sediments - rocks - pore waters
Marine/Coastal, Abundance, Modelling, Nitrogen, Salinity, Seagrass, Species diversity, Tropical environment, ISW, Kenyan Coast, ISW, Mozambique, Inhaca, ISW, Tanzania, Zanzibar, Thalassia hemprichii (Ehrenberg) Ascherson, 1871, Thalassodendron ciliatum (Forssk.) Hartog

Geographical coverage
ISW, Kenyan Coast Stations [Marine Regions]
zone 1
Coordinates: MinLong: 39,8776; MinLat: -3,234 - MaxLong: 40,5514; MaxLat: -2,4192 [WGS84]
Coordinates: MinX: 597500; MinY: 9642500 - MaxX: 672500; MaxY: 9732500 [UTM37S]
zone 2
Coordinates: MinLong: 39,473; MinLat: -4,1389 - MaxLong: 40,1924; MaxLat: -3,098 [WGS84]
Coordinates: MinX: 552500; MinY: 9542500 - MaxX: 632500; MaxY: 9657500 [UTM37S]
zone 3
Coordinates: MinLong: 39,1127; MinLat: -4,7271 - MaxLong: 39,6981; MaxLat: -3,9578 [WGS84]
Coordinates: MinX: 512500; MinY: 9477500 - MaxX: 577500; MaxY: 9562500 [UTM37S]
ISW, Mozambique, Inhaca [Marine Regions]
ISW, Tanzania, Zanzibar [Marine Regions]

Temporal coverage
March 1997
February 1998

Taxonomic coverage
Thalassia hemprichii (Ehrenberg) Ascherson, 1871 [WoRMS]
Thalassodendron ciliatum (Forssk.) Hartog [WoRMS]

% seagrass coverage, Current velocity water, Dry weight biomass, Median grain size, Organic carbon (OC), Salinity

Koninklijk Nederlands Instituut voor Onderzoek der Zee; NIOZ Yerseke, moredata owner

Dataset status: In Progress
Data type: Data
Data origin: Research: field survey
Metadatarecord created: 2007-03-22
Information last updated: 2014-01-10
All data in the Integrated Marine Information System (IMIS) is subject to the VLIZ privacy policy