Land-ocean fluxes and transformation
Talks:
09:15
Abstract 183
Engaging children’s voices in decision-making for tourism management through drawings in Indonesia
by Connie Kwong
ZMT
Ocean tourism is a primary source of income for many small-island and coastal communities. Participatory processes have been advocated to develop and implement community-based management plans to address various problems induced from tourism development and achieve the desired and sustainable futures. One debate over such processes is the under-representation of children. This paper aims to use creative method to explore children’s representations and temporal orientations towards the future of the marine environment of a tourist destination on Gili Trawangan in Indonesia. A total of 91 children participated in four drawing workshops followed by a short interview in January 2023. They were asked to make two drawings based on the following broad questions: 1) What do you see/do at the sea and coast now? and 2) What do you want to see/do at the sea and coast 5 years later? The children have represented uses of the sea and coast by themselves, other users as well as the marine animals. They have also expressed various temporal orientations through their drawings and interview, including anticipation, hope, expectation, concern, anxiety and despair. These temporal orientations offer a very strong set of information to be included in decision-making workshops and policy recommendations. This paper has reiterated that children do have a stake in such decision-making processes for their sustainable futures and thus their voices need to be heard. It adds to the existing literature by engaging children’s voices to promote inter-generational justice, and calls for increased efforts in the realisation of such component in sustainable development.
09:30
Abstract 169
‘Blue Carbon’ projects on the voluntary carbon market as a tool in climate change mitigation
by Tim Jennerjahn | Judith Reise | Nora Wissner | Leon Janas | Victoria Liste | Felix Fallasch
Leibniz Centre for Tropical Marine Research | Öko-Institut e.V. | Öko-Institut e.V. | Öko-Institut e.V. | Öko-Institut e.V. | Öko-Institut e.V.
The demand for ‘Blue Carbon’ projects (BCP) on the voluntary carbon market (VCM) is high because of the strongly increasing popularity of ‘Blue Carbon’ as a tool in climate change mitigation. However, as of October 2023 there are only 12 projects accredited worldwide. There is a number of financial, political, governance, biophysical and technological barriers that are slowing the progress required to meet the high demand for BCPs. In the consultancy project “Climate mitigation measures in coastal regions and waters – Accounting, crediting and financing of blue carbon measures” for the German Federal Environment Agency (Umweltbundesamt) we are analyzing how existing BCPs have overcome these barriers.
We introduce carbon crediting programs and the overarching criteria of additionality and permanence. We then analyze BCPs, the vast majority of which is situated in mangrove forests, for five major criteria, which are: (i) type of intervention, (ii) climate mitigation impact incl. applied standard/ quantification methodology, (iii) environmental and social impacts, (iv) monitoring mechanisms, and (v) costs of implementation.
At the heart of a BCP is the quantification of greenhouse gas (GHG) fluxes and carbon stocks. All carbon crediting programs have own methodologies, which are largely based on IPCC and UNFCCC guidelines. The soil stock is the largest carbon pool of a ‘Blue Carbon’ ecosystem, but the least well addressed in carbon crediting programs and least well determined in BCPs. The majority of BCPs have little or no GHG and carbon stock data, but use literature data or default values. Moreover, the non-consideration of allochthonous carbon i.e. the portion of carbon stored in soils that does not result from CO2 uptake and, hence, is not climate-active in the project area, represents a source of error.
It appears that current approaches in carbon crediting programs still face numerous difficulties in establishing projects and carbon accounting.
09:45
Abstract 168
Legal analysis to shed light on power relationships in wastewater management – motivation and approach
by Roald Leeuwerik
ZMT
Wastewater management is still largely approached as a politically neutral endeavor. Only recently different authors have illustrated how wastewater management brings together stakeholders with different perspectives on the impacts of wastewater and appropriate management approaches. These stakeholders do generally not have equal opportunities to shape management opening it up to politics. To understand political interactions in terms of their drivers and implications, different methods are used as part of the TransTourism project. A central focus for analysis are “knowledge flows” between stakeholders in the process of management formulation, which were visualized with network mapping interviews. The resulting knowledge flow maps provide an insight in policy practice, aiding in the identification of important decision-makers, knowledge providers and important relationships as perceived by a larger group of interviewees. On the other side of policy practice stands the more rigid legal practice in the form of policies on wastewater. To shed light on how knowledge flows are described in wastewater policies, a search strategy to analyze policy documents has been developed. An important end product of the legal analysis is the generation of a knowledge flow map. The generated map can then be compared with the knowledge flow maps generated during the network mapping interviews. At that stage, the kinds of knowledge flowing between different stakeholders in policy and in practice, as well as the potential absence of relationships in policy or in practice can help in identifying power asymmetries and potential implications of existing governing practices. During the presentation, apart from the motivation behind the legal analysis, the strategy to analyze policy documents will be explained and attendees will be invited to share their thoughts.
10:00
Abstract 148
Effect of wastewater on the functional structure of reef-fish assemblages: a systematic review and meta-analysis
by Ramón Alejandro Plazas Gómez
ZMT
Wastewater’s impact on coral reefs, a global concern for decades, threatens over one quarter of the world’s coral reefs. High disturbances result in reduced coral and reef fish abundance, shifting from coral to algae cover. Detecting responses to low disturbances is challenging, as traditional taxonomy-based indices overlook biological and functional differences among species. The functional approach, incorporating species traits, proves more sensitive in assessing disturbances. Despite its advantages, few studies, especially in the marine environment, address wastewater pollution through this approach. In our systematic literature review, we focused on the direct impact of wastewater and water quality changes on reef fishes, examining publications in English from 1980 to 2021. Our criteria included demonstrating the effects of urban wastewater on at least one reef-fish trait and providing fish abundances in polluted versus control scenarios. Fifty-two studies from 20 countries were analyzed, reporting 474 species from 75 families.
We summarize the traits affected by wastewater disturbances, revealing herbivore fish and big predators as highly impacted by pollution. The meta-analysis shows a reduced functional richness in impacted areas and changes the functional structure of reef fish assemblages. We discuss differences between natural and anthropogenic disturbances and compare the functional approach’s sensitivity with taxonomy-based methods. Our findings emphasize the advantages of a functional trait-based approach, showcasing its utility across diverse geographic scales. By shedding light on the specific impacts of wastewater on reef fish traits, our study contributes to understanding and mitigating the consequences of sewage inputs on coral reef ecosystems.
Poster
PA3: 12:00 – 12:30
Abstract 153
Using photo voicing and mental modeling to identify climate change effects to coastal tourism; case study of Kilifi, Kenya
by Lucy Atieno
ZMT, and Universität Bremen
Introduction: Approximately 80% of all tourist travel activities globally takes place in coastal areas, making marine environments a crucial driver in the tourism industry. However, climate change has caused significant damage to marine environments, posing severe consequences for coastal communities, especially those dependent on tourism revenue.
Methods: My study uses observations from tourism dependent communities in Kilifi, coastal Kenya, to identify climate change effects on coastal tourism. Its analysis which includes a gender component, contributes to filling a gap for locally held knowledge, whose presence in conventional climate discourses remains in distant or diminished forms. Observations for this study were captured through photovoicing and mental modeling interviews with respondents at the study site, as participatory data collection methods.
Results: Results show climate change effects commonly associated with tourism in the marine socio-ecological system; the specific focus of observations captured by each of the two data collection methods;, and the convergence of observed data to implications for coastal tourism.
Discussion: Local observations, informed by tourism activities situated off shore and inland, provided a livelihood context to frame concepts of climate change in the data poor socio-ecological system.
Conclusion. These findings which map onto foundational assumptions of feminist political ecology, underscore the importance for policy and practice to incorporate diverse perspectives in deliberating climate change issues.
Abstract 159
Geospatial Analysis of Mangrove Loss, Fragmentation, and its Correlation with Land Use Change in Sarawak, Malaysia
by Azelea Kong
University of Bremen
The ecological integrity of Sarawak’s mangroves in Malaysia is increasingly compromised by land-use changes, underscoring an urgent need for the conservation of these ecosystems that are pivotal for coastal protection and biogeochemical cycling. Employing the Global Mangrove Watch dataset from 1996 to 2020 with QGIS, this study has identified a total mangrove cover reduction of 4,627 hectares, equating to approximately 3.75% of the 1996 extent. Notably, the Daro and Kuching districts experienced the highest rate of mangrove loss at 75.45 and 40.81 hectares per year respectively. Various fragmentation statistical metrics were quantified and it was found that between the years 1996 and 2020, Sarikei and Kuching saw a 33% and 26% rise in patch density respectively, with significant reductions in mean patch area indicating a rise in mangrove fragmentation. Finally, the employment of the Global Land Cover Dataset by National Mapping Organisations and the Dinamica EGO modelling software has allowed for a nuanced analysis of land-use transitions impacting mangrove landscapes. These findings delineate specific districts within Sarawak—particularly Daro, Kuching, and Sarikei—where the dual threats of loss and fragmentation are especially pronounced. By highlighting the main districts and categorising the principal land-use changes driving mangrove ecosystem degradation, the study paves the way for the development of effective, localised conservation strategies.
Abstract 161
Responses of functional traits of tropical seagrass to ocean acidification – a case study of Hainan Island, South China
by Muqiu ZHAO | Yunfeng SHI | Jiali CAI | Zhaoyang LI | Zhiqiang SHI | Siyang MA
Hainan Tropical Ocean University | Hainan Tropical Ocean University | Hainan Tropical Ocean University | Hainan Tropical Ocean University | Hainan Tropical Ocean University | Hainan Tropical Ocean University
Seagrass meadows are important Blue Carbon ecosystems in tropical coastal areas, provide many ecosystem services including carbon sequestration and storage, and have been declining due to human activities and global climate change. Plant functional traits could predict community response to environmental change and the effects of changes in community composition on ecosystem processes, and have been deemed the “Holy Grail” in ecology.
We used a trait-based approach in which morphological and physiological traits of seagrass were measured in laboratory experiments under uni- or multi-factor treatments to study the response of plant functional traits to ocean acidification (pH 8.2, 7.8, 7.3, 6.5). We found that acidification promotes the increase of aboveground and belowground biomass, leaf length (morphological traits) and the accumulation of non-structural carbohydrates, osmoregulatory substances, and secondary metabolites (physiological traits). The overall impact of ocean acidification on seagrass growth is positive. However, multiple environmental stressors may affect the results. We conducted experiments on the interaction between acidification and salinity, and the results showed that salinity stress reduces the positive effects of acidification.
In the future, we will further expand related research and use seagrass functional traits as a link to explore the relationship between environmental stress and the carbon sequestration function of tropical seagrass meadows. We hypothesize that environmental stress indirectly affects the carbon sink capacity of tropical seagrass meadows by directly affecting plant functional traits. We aim to provide data support for promoting the protection and restoration of coastal ecosystems under land-sea coordination and increasing carbon sinks in Blue Carbon ecosystems.
Abstract 170
‘Blue carbon’ storage and sequestration rates in mangrove restoration: Insights from a 30-Year Chronosequence in Qi‘ao Island, China
by Chenxi Yu
ZMT
The pivotal role of mangroves in the blue carbon stock demands special attention due to their status as carbon-rich forests, which do not maintain steady-state equilibrium on a decadal time scale. Despite the increasing promotion of mangrove restoration efforts to offset mangrove losses, our understanding of ecosystem development and functional equivalence in restored mangroves remains limited. Notably, the critical parameter of the time elapsed since the stabilization of mangrove structures has surprisingly been consistently overlooked in mangrove carbon stock projections over the past 30 years. This oversight creates a gap in comprehending the long-term effectiveness and ecological dynamics of mangrove restoration initiatives, hindering our ability to accurately assess their contribution to the blue carbon stock.
This study posits that the age structure of ecosystems is crucial in modulating mangrove carbon stocks. To explore this, a 30-year chronosequence analysis was conducted on the aboveground and belowground biomass, as well as soil carbon stock of mangroves in Qi‘ao Island, China. The results highlight a decline in plant carbon sink capacity with ecosystem age, while the soil carbon sequestration rate remains relatively constant over many years. These findings underscore the necessity of considering mangrove age structures in global projections of above- and belowground carbon reservoirs, providing insights into historical changes in coastal morphology. The study advocates for collaborative international efforts to comprehensively quantify the multidecadal mangrove carbon balance. This can be achieved by leveraging age-based parametric equations and utilizing time series data of mangrove age maps at regional scales, facilitating a more accurate understanding of the intricate dynamics of mangrove ecosystems.
Abstract 184
Investigation of submarine groundwater discharge in tidal bays
by Cátia M. Ehlert Von Ahn | Melvin Feldmeier | Nils Moosdorf
Leibniz Centre for Tropical Marine Research | Leibniz Centre for Tropical Marine Research | Leibniz Centre for Tropical Marine Research
The impact of submarine groundwater discharge (SGD) on coastal biogeochemistry is currently under intense investigation. The term SGD covers a wide range of processes, compositions and origins, including not only the direct discharge of fresh groundwater but also mixing with recirculated saline porewater through permeable surface sediments. The mixing zone, called subterranean estuary (STE), significantly influences the fluxes of solute to the coastal waters. Therefore, our aim is to investigate SGD and to assess the behavior of elements in the STE and its consequences for the coastal waters. The study area is Königshafen Bay (KB) (North Frisian island of Sylt, Germany), a tidal area in the eastern North Sea. Sampling included sediment porewater (down to 150 cmbsf) and surface waters in the KB, and potential nearby surface endmembers. Samples were collected for major and minor elements, dissolved inorganic carbon (DIC), total alkalinity, hydrogen sulphide, and nutrients. The porewaters showed a decrease in salinity with depth with values down to 2 PSU at 50 cmbsf at some sites. This indicates that a mixing of seawater with fresh groundwater, suggesting that SGD is an important phenomenon and probably contributes to the coastal biogeochemistry at this site. Further studies will continue to quantify SGD and to evaluate the role of STE in the final fluxes to the coastal waters, particularly comparing the findings from KB with another site in India, focusing climatic effects on the influence of STE.
Abstract 189
Tourism impact on wastewater-derived nutrient pollution on the tropical small island Gili Trawangan, Indonesia
by Sarah Zwicker | Nils Moosdorf | Marie Fujitani
ZMT, Uni Bremen | ZMT, Uni Kiel | ZMT, Uni Bremen
While mass tourism secures livelihood on the 6 km² small island of Gili Trawangan, wastewater management in the tourism sector displays a sustainability challenge. Without an advanced island-wide wastewater treatment concept, most of the ca. 400 hotels discharge their wastewater untreated into open septic tanks in the ground. From there, it enters the groundwater and the marine environment, introducing wastewater-derived nutrients to marine ecosystems. However, from early 2020 to 2022, the COVID-19 pandemic reduced global tourism to a minimum, interrupting the discharge of tourism-generated wastewater on Gili Trawangan.
This study used this quasi-experiment as an opportunity to investigate the impact of tourism on the island’s nutrient pollution. From March 2022 to September 2023, i.e., before, during and after the recovery of mass tourism, dissolved organic nutrients were measured monthly in six coastal groundwater wells in the urban hotel district and in remote areas of Gili Trawangan. Similarly, d15N stable isotopes were measured in marine macroalgae Padina, collected bi-monthly from six marine sites near the respective groundwater wells. A seasonal comparison of the sites before and after the return of tourism showed a doubling of the NOx concentration in groundwater of the urban hotel district, reaching mean values up to 1750 µmol/L in the dry season 2023. The control sites showed significantly lower levels of NOx and no increase with the return of tourism. Similarly, d15N values in Padina sampled near the hotel district stood out with values above 6 ‰, clearly indicating wastewater as origin of nitrogen in the marine environment. They showed a 15 % increase of the mean dry season value with the return of tourism. This study illustrates the strong contribution of the tourism sector on nutrient pollution on Gili Trawangan. It showcases the need to improve land-based wastewater management to protect marine ecosystems from eutrophication.