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Please use this identifier to cite or link to this item:
http://hdl.handle.net/1834/1284
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| Title: | An assessment of seagrass survival and functioning in response to manipulations in sediment redox at Nyali Lagoon, Kenya |
| Authors: | Gwada, P. |
| ASFA Terms: | Biomass
Sediments
Seagrass |
| Issue Date: | Feb-2004 |
| Abstract: | Thalassodendron ciliatum was studied during two monsoon cycles of the year 2001/2002 to
determine the interactive effects of experimentally elevated redox potentials on in situ plant
structure and shoot-root (S/R) biomass allocation patterns. Thalassodendron plants from
shallow back-reef tidal pools were substrate manipulated under ambient field conditions for
90 days on each monsoon cycle. Plant sampling was done from quadrats impacted with
organic substrates at three different concentrations (proxies to induce differential redox
potentials). Our data show clear differences (at ANOVA, p < 0.05) in Eh and plant traits from
2 treatment effects and from monsoon seasonality effects. Thalassodendron had relatively
higher canopy cover, shoot density, shoot blade density, and absolute shoot and root biomass
at control sites than at two substrate-impacted sites. Between the monsoons, the same plant
traits were higher during the North-East Monsoons (NEM) than they were during the South-
East Monsoons (SEM). Thalassodendron beds experienced negative carbon balances within
3 weeks of impaction and were dead by 2 months, which coincided with periods when
daytime redox potential values consistently lower than –70mV. S/R ratios were relatively
higher at high substrate impacted sites and during the South-East Monsoons (SEM), both
conditions also coinciding with higher reducing conditions. Final S/R ratios were 0.32 and
0.34 during NEM and SEM periods respectively at control sites, and 0.33, 0.42, and 0.55, and
0.34, 0.38 and 0.60 at zero, mid and high substrate impacted sited during NEM and SEM
depth respectively. About 60% and 95% of root biomass were distributed in the top 10-cm
and top 20-cm of soil respectively. Our findings support our hypothesis that reduced redox
concentrations would increase plant stress and, consequently, decrease investments in growth
capacity. |
| Description: | WIOMSA/MARG-I/2004/01. |
| URI: | http://hdl.handle.net/1834/1284 |
| Related document: | http://www.wiomsa.org/ |
| Appears in Collections: | Other Reports
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