221
8.2.6 Chemical Cycles Disrupted by White
Mangrove Logging in North-Brazil?
Mirko Wölfelschneider
1*
, Véronique Helfer
2
, Martin
Zimmer
2
, Moirah Paula Machado De Menzes
3
, Ulf
Mehlig
3
1
Universität Bremen, Bibliothekstraße 1, 28359 Bremen,
Germany
2
Leibniz Centre for Tropical Marine Sciences,
Fahrenheitstraße 6, 28359 Bremen, Germany
3
Federal University of Pará – Campus Bragança,
Bragança – PA, 68600-000, Brazil
*corresponding author: mirco.woelfelschneider@
gmx.de
Keywords: Mangrove-logging, Sustainable resource-use,
Chemical cycle, Mangroves
Mangroves provide an array of ecosystem services to
coastal communities, including coastal protection and livelihood. Yet, these fragile environments are among the most
threatened ecosystems on the planet. As human populations,
particularly in developing nations continue to grow, the number of people dependent on mangroves for their survival has
increased. ‘No-take’ policies are no longer a feasible solution to protect and preserve mangroves for future generations, meaning there is an urgent need for well-conceived
management plans. Communities along the coastline of
North Brazil practice a traditional form of selective
mangrove- logging involving the White mangrove
(Laguncularia racemosa). The felled trees of this species
have the ability to re-grow, thus this activity is often considered as sustainable resource-use. However, its subsequent
ecological impacts have yet to be investigated. This study
investigates how the re-growth process of the White mangrove influences plant chemistry and subsequent elementcycling within the ecosystem. Leaf and sediment samples
obtained directly from the trees at four different stages of
re-growth and their surrounding areas were analyzed for carbon and nitrogen content to gain an overview of the systems
dynamics. Pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) was then employed to gain a more detailed
insight into the chemical composition of both mangrove
leaves and the organic matter of the sediment. The results
show significant changes in the nitrogen content of leaf tissues during the different stages of the re-growth process. For
the carbon level no such significant changes were revealed.
Sediment sample analyses revealed trends in changes of
organic matter, carbon or nitrogen content, however these
could not be related to the changes within the leaf chemistry.
The results from this study support the current assumption
that selective logging is a sustainable resource-use with a
very low impact on the surrounding ecosystem.
8.2.7 Long Term Impact of Experimental
Harvesting on a Tropical Seagrass Meadow
in Gazi Bay, Kenya
Charles Cadier
1,2,3*
, Anna-Maria Frouws
1,2
1
School of Applied Sciences, Edinburgh Napier
University, EH11 4BN, Edinburgh, UK
2
Kenya Marine and Fisheries Research Institute, P. O.
Box 81651, Mombasa, Kenya
3
University of the Basque Country, Areatza z/g 48620
Plentzia-Bizkaia, Spain
*corresponding author: charlescadier@hotmail.fr
Keywords: Canopy removal, Tropical seagrass meadow,
Recovery
Seagrass meadows provide a wealth of ecosystem services, among which the provision of habitats for many taxonomic groups and significant contribution to sediment carbon
storage. Along the African coast research on seagrasses is
still limited. This study examined the recovery capacity of
four experimentally harvested (monthly removal of leaves
during 1.5 years) plots (3*2 m) in a seagrass meadow in Gazi
Bay, Kenya, and compared these with four control plots.
Recovery was measured 6 months after disturbance ended.
Seagrass health was determined through leaf puncturing
techniques and leaf counts. Macrofauna was sampled through
dropsamples and cores. Soil organic carbon was measured
through Loss on Ignition. The removal phase showed a loss
in fauna abundance (252.8 ± 73.3 and 1541.8 ± 606.4 (mean
abundance ± SD) respectively) and % organic matter in sediment (1.5% ± 0.07 and 2.7 ± 0.70 (mean % organic matter ± SD) respectively) within removal plots compared with
control plots. After 6 months of recovery, results displayed a
tendency for lower growth rate for recovering plots compared to control plots (4.6 ± 2.1 and 7.0 ± 3.2 mm d
−1
(mean
growth rate ±SD) respectively). The % organic carbon in
sediment displayed a similar trend (0.8% ± 0.4 and
3.0 ± 0.9% (mean % organic carbon ± SD) respectively).
Fauna has been sampled within recovering plots and shows
clear signs of disturbance, results are expected in July. These
preliminary results indicate that half a year after the end of
the disturbance, experimentally harvested seagrass meadows
do not show signs of recovery.
8.2.8 Using a Social-Ecological System (SES)
Framework as a Tool for Stakeholder
Deliberation of Sustainability Challenges
in the Gulf of Nicoya, Costa Rica
Vigneshwaran Soundararajan
1*
, Stefan Partelow
1
1
Leibniz Center for Tropical Marine Research (ZMT),
Fahrenheitsraße 6, 28359 Bremen, Germany
*corresponding author: vigneshwaran.soundar@gmail.
com
Appendices
8.2.6 Chemical Cycles Disrupted by White
Mangrove Logging in North-Brazil?
Mirko Wölfelschneider
1*
, Véronique Helfer
2
, Martin
Zimmer
2
, Moirah Paula Machado De Menzes
3
, Ulf
Mehlig
3
1
Universität Bremen, Bibliothekstraße 1, 28359 Bremen,
Germany
2
Leibniz Centre for Tropical Marine Sciences,
Fahrenheitstraße 6, 28359 Bremen, Germany
3
Federal University of Pará – Campus Bragança,
Bragança – PA, 68600-000, Brazil
*corresponding author: mirco.woelfelschneider@
gmx.de
Keywords: Mangrove-logging, Sustainable resource-use,
Chemical cycle, Mangroves
Mangroves provide an array of ecosystem services to
coastal communities, including coastal protection and livelihood. Yet, these fragile environments are among the most
threatened ecosystems on the planet. As human populations,
particularly in developing nations continue to grow, the number of people dependent on mangroves for their survival has
increased. ‘No-take’ policies are no longer a feasible solution to protect and preserve mangroves for future generations, meaning there is an urgent need for well-conceived
management plans. Communities along the coastline of
North Brazil practice a traditional form of selective
mangrove- logging involving the White mangrove
(Laguncularia racemosa). The felled trees of this species
have the ability to re-grow, thus this activity is often considered as sustainable resource-use. However, its subsequent
ecological impacts have yet to be investigated. This study
investigates how the re-growth process of the White mangrove influences plant chemistry and subsequent elementcycling within the ecosystem. Leaf and sediment samples
obtained directly from the trees at four different stages of
re-growth and their surrounding areas were analyzed for carbon and nitrogen content to gain an overview of the systems
dynamics. Pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) was then employed to gain a more detailed
insight into the chemical composition of both mangrove
leaves and the organic matter of the sediment. The results
show significant changes in the nitrogen content of leaf tissues during the different stages of the re-growth process. For
the carbon level no such significant changes were revealed.
Sediment sample analyses revealed trends in changes of
organic matter, carbon or nitrogen content, however these
could not be related to the changes within the leaf chemistry.
The results from this study support the current assumption
that selective logging is a sustainable resource-use with a
very low impact on the surrounding ecosystem.
8.2.7 Long Term Impact of Experimental
Harvesting on a Tropical Seagrass Meadow
in Gazi Bay, Kenya
Charles Cadier
1,2,3*
, Anna-Maria Frouws
1,2
1
School of Applied Sciences, Edinburgh Napier
University, EH11 4BN, Edinburgh, UK
2
Kenya Marine and Fisheries Research Institute, P. O.
Box 81651, Mombasa, Kenya
3
University of the Basque Country, Areatza z/g 48620
Plentzia-Bizkaia, Spain
*corresponding author: charlescadier@hotmail.fr
Keywords: Canopy removal, Tropical seagrass meadow,
Recovery
Seagrass meadows provide a wealth of ecosystem services, among which the provision of habitats for many taxonomic groups and significant contribution to sediment carbon
storage. Along the African coast research on seagrasses is
still limited. This study examined the recovery capacity of
four experimentally harvested (monthly removal of leaves
during 1.5 years) plots (3*2 m) in a seagrass meadow in Gazi
Bay, Kenya, and compared these with four control plots.
Recovery was measured 6 months after disturbance ended.
Seagrass health was determined through leaf puncturing
techniques and leaf counts. Macrofauna was sampled through
dropsamples and cores. Soil organic carbon was measured
through Loss on Ignition. The removal phase showed a loss
in fauna abundance (252.8 ± 73.3 and 1541.8 ± 606.4 (mean
abundance ± SD) respectively) and % organic matter in sediment (1.5% ± 0.07 and 2.7 ± 0.70 (mean % organic matter ± SD) respectively) within removal plots compared with
control plots. After 6 months of recovery, results displayed a
tendency for lower growth rate for recovering plots compared to control plots (4.6 ± 2.1 and 7.0 ± 3.2 mm d
−1
(mean
growth rate ±SD) respectively). The % organic carbon in
sediment displayed a similar trend (0.8% ± 0.4 and
3.0 ± 0.9% (mean % organic carbon ± SD) respectively).
Fauna has been sampled within recovering plots and shows
clear signs of disturbance, results are expected in July. These
preliminary results indicate that half a year after the end of
the disturbance, experimentally harvested seagrass meadows
do not show signs of recovery.
8.2.8 Using a Social-Ecological System (SES)
Framework as a Tool for Stakeholder
Deliberation of Sustainability Challenges
in the Gulf of Nicoya, Costa Rica
Vigneshwaran Soundararajan
1*
, Stefan Partelow
1
1
Leibniz Center for Tropical Marine Research (ZMT),
Fahrenheitsraße 6, 28359 Bremen, Germany
*corresponding author: vigneshwaran.soundar@gmail.
com
Appendices