Coastal resources and sustainable blue economy
Talks:
10:30
Abstract 187
Four years of sea grape research: synopsis and outlook
by Lara E. Stuthmann | Beatrice Brix Da Costa | Hoang Trung Du | Karin Springer | Andreas Kunzmann
ZMT Bremen | Marine Botany, University Bremen | Institute of Oceanography Vietnam | Marine Botany, University Bremen | ZMT Bremen
Sea grapes (Caulerpa lentillifera) are edible, green macroalgae that are cultivated mainly in the Philippines, Japan and Vietnam. The seaweed stands out as a candidate to meet the increasing demand of sea vegetables, due to the special, caviar-like texture, as well as the nutritious composition. In the project SeaGrapes we investigated the aquaculture of sea grapes in tidal ponds in Van Phong Bay, Vietnam in partnership with researchers from the Institute of Oceanography (IO) and commercial VIJA farm over the last four years. We investigated connections between the ecophysiology and the biochemical composition of the alga with the target to design tools that farmers could use to increase the quality and quantity of the product. Light management over the production cycle, as well as manipulation of the nutritional value through adjustment of environmental parameters and resource-efficient co-cultivation were identified. We would like to share a summary of the main project outcomes, our ongoing work on this topic, as well as some ideas, where research in the context of marine phycoculture could lead to in the future.
10:45
Abstract 181
Deep dive into coral habitat mapping: A comparative evaluation of manual annotation and automated segmentation techniques
by Khishma Modoosoodun Nicolas | Hauke Reuter | Arjun Chennu
Leibniz Centre for Tropical Marine Research & University of Bremen | Leibniz Centre for Tropical Marine Research (ZMT) | Leibniz Centre for Tropical Marine Research (ZMT)
Coral reef ecosystems, characterized by their intricate biodiversity and ecological significance, underscore the crucial need for effective and accurate habitat mapping methodologies. This study undertakes a comparative evaluation of two distinct approaches for extracting coral colonies in benthic habitat mapping. It involves manual annotation using TagLab and automated annotation using the Segment Anything Model (SAM), with the objective of contributing to the refinement of coral habitat mapping techniques. The main goal is to create a benthic habitat map with a focus on spatial coral ecology, leveraging instance segmentation. A rule-based workflow is implemented for SAM and Taglab respectively, where coral masks are generated and evaluated using Intersection over Union (IoU) accuracy metrics and summary statistics are calculated. The IoU accuracy metric measures the overlap between automatically predicted masks and manually annotated ground truth masks. Comparing Taglab and SAM masks allows for the assessment of the automatic segmentation model’s performance against manual annotations. The IOU score results range between 0.50 to 0.85 for tile level comparison. The insights gained from this comparison emphasizes the significance of automating habitat mapping processes using deep learning, providing a foundation for efficient and scalable coral ecology studies. The findings of the automated segmentation method, like SAM shows promising results that can significantly reduce the time and effort required for habitat mapping compared to manual annotation and also facilitate scalable studies, allowing the analysis of larger spatial extents. Additionally, the study highlights the significance of automated methods in providing a standardized and consistent approach to coral habitat mapping.
11:00
Abstract 156
Navigating Coastal Fisheries Dynamics in Peru: An Integrated Approach using Social-Ecological Network Analysis and Participatory Modelling
by Michael Kriegl | Lotta C. Kluger | Martín Salazar Céspedes | Edward Barriga Rivera | Ben Nagel | Matthias Wolff | Achim Schlüter
Leibniz Centre for Tropical Marine Research (ZMT) | Center for Ocean and Society (CeOS), Kiel University | Instituto del Mar del Perú (IMARPE) | Instituto del Mar del Perú (IMARPE) | Leibniz Centre for Tropical Marine Research (ZMT) | Leibniz Centre for Tropical Marine Research (ZMT) | Leibniz Centre for Tropical Marine Research (ZMT)
Tropical coastal systems are dynamic environments characterized by complex relationships between social and ecological entities. Small-scale resource users navigate these fluctuating seascapes through strategies such as diversifying target species, adopting innovative fishing techniques, and migrating between regions. To understand these dynamic processes, we used network tools to analyze 25 years (1996-2020) of fisheries data from two contrasting Peruvian bays, tracking the evolution of connectivity patterns between resource users, target species and landing sites in time and space. This quantitative analysis was complemented by participatory workshops with local resource users in which we reconstructed social-ecological timelines for the studied regions, illustrating how ecological, economic and social events have shaped the trajectories of the coastal system in the past. In the second phase of the project, we shift our perspective from looking back to projecting ahead and use qualitative models to simulate social-ecological futures for coastal Peru. In a participatory process, we develop network models that capture the social and ecological dynamics relevant for the local resource use sector. Using qualitative mathematical modelling, specifically loop analysis, we then ask “What If…?” questions based on locally- downscaled SSP scenarios, assessing their outcomes for both people and the environment. Our overarching goal is to develop a comprehensive, versatile and inclusive decision- support tool tailored to data-limited settings in tropical regions, empowering coastal communities to plan for the future, assess the sustainability of management options and adapt to changing realities. In addition, this effort establishes a robust foundation for larger- scale modeling endeavors in the region. Understanding past trajectories as well as potential future pathways of coastal systems is critical for deciphering the complex dynamics between resource management, conservation efforts and community resilience. In a rapidly changing world, this integrated system understanding is indispensable for making informed decisions and securing the livelihoods of coastal communities.
11:15
Abstract 149
How Bangladesh Blue Economy Stakeholders percept blue governance?
by Jewel Das | Maheshwaran Govender | Marion Glaser
ZMT | ZMT | ZMT
Given the significance of blue economy themes for the Sustainable Development Goals, the ongoing ‘Decade of Ocean Science and Sustainable Development’ by the United Nations underscores the importance of sustainable ocean management. Bangladesh, aligning with this global agenda, has prioritized blue economy policies, leading to substantial investments. Using the participatory network mapping technique, netmap, our research delves into the perspectives of various stakeholders on blue economy governance networks in Bangladesh. Representatives from diverse blue economy stakeholder groups engaged in collaborative mapping exercises to depict their perceptions of formal and informal ocean governance relationships among identified actors. This research finds four distinct datasets that capture stakeholder-specific views on the Bangladesh blue economy governance network. A notable finding is the consensus among all stakeholder groups that government actors hold central and influential roles.
Conversely, local resource users and coastal communities emerge as largely excluded from the network perceptions of the most stakeholder groups, indicating a low level of connectedness and influence for this marginalized group. The presence of international organizations and foreign developmental cooperation underscores the significant role played by foreign investors in coastal Bangladesh. Moreover, our findings suggest a tendency toward centralization in blue economy governance in Bangladesh, coupled with a notable representation of private stakeholders and development cooperation, aligning with assertions that current blue economy initiatives lean towards large-scale development. In light of these findings, our study advocates for inclusive governance and decision-making processes in terms of knowledge, policy, and action. This recommendation aims to mitigate the risk of further marginalizing local resource users and other members of coastal communities in Bangladesh, who are already at risk of exclusion.
Poster
PA1: 14:45 – 15:15
Abstract 152
A phylogenomic perspective on the genic view of species and speciation
by Martin Helmkampf | Floriane Coulmance | Melanie Heckwolf | Oscar Puebla
ZMT | ZMT | ZMT | ZMT
According to the genic view of species and speciation, species are essentially formed and characterized by the genes that underlie functional divergence. Here, we take a phylogenomic approach to assess this view at the scale of a whole radiation. The hamlets (Hypoplectrus spp.) are a group of reef fishes from the wider Caribbean that differ essentially in terms of color pattern and are reproductively isolated through strong assortative mating. A total of 335 genomes from 15 locations reveal that > 60 % of the species are phylogenetically unresolved at the whole-genome level. At the gene-tree level we identified just one genomic region, centered around the casz1 transcription factor, that shows a clear phylogenetic signal across the radiation. These results show that phenotypic diversification and reproductive isolation may unfold in a genomic backdrop that is dominated by incomplete lineage sorting and introgression except for very few and specific genomic regions.
Abstract 154
Harmful algal blooming micro-algae in Kenya’s Coastal Waters
by Nancy A. Oduor | Nils Moosdorf | Anke Kremp
Department of Biogeochemistry and Geology, Leibniz Center Tropical Marine Research (ZMT) and Eracoma | Department of Biogeochemistry and Geology, Leibniz Center Bremen| Department of Biological Oceanography, Leibniz Institute for Baltic Sea Research
Harmful algal blooms (HABs) are a threat to coastal water quality, marine biodiversity, and human health. The knowledge about HABs and associated phycotoxins is still small in tropical coastal developing countries despite the high dependence of local communities on coastal and marine resources for food and livelihoods and the growing evidence of the global increase in HABs frequency, toxicity, and geographical expansion. Lack of HAB monitoring thus creates a high risk of exposure due to uncertainty. This study assessed the spatial and temporal variability of potential HAB-forming species in Kenya’s coastal waters. The preliminary results from 463 samples collected over a series of 10 coastal surveys conducted over 267 Km of Kenya’s coastline between August 2021 and July 2022 revealed the presence of 87 potential algal blooming species belonging to 47 genera dominated by species capable of producing toxins, causing physical harm and high biomass at 41, 31 and 24 1 % respectively. The taxonomic composition was also dominated by dinoflagellates at 7%, followed by diatoms, cyanobacteria, and silicoflagellates at 39, 12 and 2%, respectively. About 92 % of the toxin-producing species were in established in the creek waters. Paralytic Shellfish Poisoning (PSP) toxin-producing dinoflagellates Alexandrium spp., Aphanizomenon spp., Gonyaulax spp., Gymnodinium spp., and Brachydinium capitatum, and Amnesic Shellfish Poisoning (ASP) Toxin producing diatoms Amphora spp., Nitzschia spp. and Pseudo-nitzschia spp. frequented the area in cell densities ranging between 5 and 1500 cells/L. Although there was no significant variation established in species richness between the dry and wet seasons, domoic acid (DA) and saxitoxins (SXTs) were not detected during the July surveys. While this study provides an important first overview of the HAB species on Kenya’s coast, longer-term studies are needed to identify bloom events and the impact of individual species.
Abstract 155
Theories of institutional change and marine privatisation
by Achim Schlüter | Kristof van Assche | Hudu Banikoi | Sidy Fall | Khadidiatou Senghor | Elimane Khane
ZMT | University of Alberta | ZMT | Uni Nantes | ZMT | IMROP
Privatisation as a process which assigns more individual property rights implies in most cases institutional change. It might be on the level of society, when formal laws, but often also informal rules are changing, or it might be on an organisational level, when an asset under an open access regime, a cooperative, or a state-owned company is converted into a privately managed entity. From this perspective it seems obvious that theories of institutional change are providing a certain understanding of privatisation processes in the marine realm. The paper uses a broad range of theories of institutional change, stemming from various social science disciplines. Processes of marine privatisation are very heterogeneous in their characteristics: some processes are informal, some take part in the business world, others in the political realm, some are to a certain degree planned, others are emerging and have more evolutionary characteristics, some are characterised by huge power asymmetries others take place under more equal footing. Therefore, it is not about the superiority of one theory above the other, but more about a question of fit. After elaborating on the theories and pointing out, under which conditions they are of particular relevance, the paper exemplifies the explanatory powers of the theories by looking at the case of privatisation of space in Saint Louis, Senegal. Due to strong restrictions for Senegalese fishers to fish in Mauritanian waters, due to the establishment of a marine protected area and more recently due to the establishment of a gas field on the doorsteps, fishers are confronted with an enclosure of their commons.
Abstract 157
Along the coast of Curacao: a densely-sampled island-wide coral reef survey elucidates benthic community composition and drivers
by Daniel Schürholz | Arjun Chennu
ZMT | ZMT
In recent decades, several temporally and spatially detailed studies of benthic sessile assemblages in coral reefs have been undertaken worldwide. Given the substantial logistical, economic and time costs linked to densely sampling large areas of coral reefs, most survey efforts have defaulted to thematically and spatially sparse sampling, producing uncertainty in the summarized descriptions of reefs. In this study we use AI to provide an island-wide description of coral reef benthic communities along the leeward coast of the Caribbean island of Curacao. We apply a machine learning workflow that uses hyperspectral transects, acquired in 2016 with the HyperDiver methodology, to produce densely-classified thematically-detailed community maps of large extents of coral reefs (over 600 Million samples). Furthermore, paired with depth readings for each sample, we provide a detailed community distribution analysis across the depth-gradient down to 18 meters. With our densely sampled maps, we provide evidence that deriving community diversity indices from sparse sampling and abstracted thematic labels can mask the true diversity of the coral reef, as well as lose information about intra-class dynamics. Combining dense community sampling with an environmental statistical analysis, we explore the possible drivers of the community compositions along the coastline of the island. The reef communities in sites situated towards the southern tip of the island show more pristine ecosystems, with high cover and diversity of corals, driven by cleaner waters further from coastal infrastructure, trash and sewage pollution. Reefs in the centre of the island, closer to the capital city Willemstad, showed the most deteriorated state, dominated by cyanobacterial mats, turf algae and large stretches of bare sediment, and with reduced diversity in corals. Sites in the northern most tip show a deteriorating status, with higher abundance of macroalgae and sponges, with a lack of reef-building corals.
Abstract 158
Optimizing Fermented Diets for Early Juvenile Sea cucumber Holothuria scabra
by Lisa Fajar Indriana | Andreas Kunzmann | Matthew James Slater
Leibniz Centre for Tropical Marine Research (ZMT); Alfred Wegener Institute (AWI) | Leibniz Centre for Tropical Marine Research (ZMT) | Alfred Wegener Institute (AWI)
Developing economically feasible and locally sourced diets for high-value early juvenile sea cucumbers, Holothuria scabra, is essential for maintaining efficient juvenile production in sustainable farming and ranching. The present study utilizes seven diet compositions consisting of fermented algae and plants; (C (control), diet seagrass Enhalus acoroides; DH, diet macroalgae Halimeda discoidea; DU, diet macroalgae Ulva lactuca; DP, diet macroalgae Padina australis; DS, diet macroalgae Sargassum polycystum; DA, diet green pond algae; DM, diet pond moss) in controlled feeding experiments for post-metamorphic juvenile H. scabra. Among all treatments, the diet green pond algae (DA) had the lowest individual Survival Rate (SR), however it also had the highest overall mean (±SE) individual Growth Rate of 0.09±0.023 g d-1. Diets E. acoroides (C) and diet P. australis (DP) had acceptable growth rates of 0.03±0.001 and 0.03±0.002 g d-1, respectively, and substantially higher SR of 80.63±4.38 and 80.63±2.77%. Over 56 days, early juvenile H. scabra showed varied Faeces Production Rates, with diet P. australis (DP) peaking at 113.99±9.54 mg g-1 h-1, green pond algae (DA) initially high at 113.05±12.13 mg g-1 h-1 but decreasing, and other diets like diet H. discoidea (DH), and diet pond moss (DM) showing significant fluctuations. Diets with the highest overall individual growth rate may be best provided to larger-sized juveniles later in the nursery production process. Overall, the results show that most macroalgae fermented diets are well accepted by juvenile H. scabra and also show that piloting diets at bigger scales and at a variety of sizes and ages of sea cucumbers will allow optimal feeding to be determined throughout the nursery production process.
Abstract 175
A novel Burkholderiaceae lineage consistently associated with gills across a reef fish radiation
by Sabrin Abdelghany | Martin Helmkampf | Oscar Puebla
Leibniz Center for Tropical Marine Research (ZMT)
Fish gills constitute a critical interface between the external environment and the circulatory system, and harbor a diverse microbial community. Nevertheless, our knowledge of fish gill microbial communities is constrained by the difficulty to cultivate these organisms and the limited power and resolution provided by metabarcoding. Here, we leverage >300 shotgun sequencing samples from gill tissue of 10 hamlet species (Hyoplectrus spp, Serranindae) collected at 11 locations across the wider Caribbean to characterize the microbial community of this reef fish radiation at the metagenomic level.
We recover a total of 57 metagenome-assembled genomes (MAGs), 22 of which belong to a previously unknown proteobacteria in the Burkholderiaceae B family that is consistently recovered across species, locations and years. This proteobacteria has complete synthesis pathways for 14 amino acids as well as a broad array of metabolic functions. A large part of the remaining 35 MAGs are related to known fish gill pathogens and coral symbionts and some of them are Novel too.
Finally, the analysis of ribosomal DNA from gill tissue versus seawater samples from the same locations indicates that the MAGs that we describe here are conspicuously absent in seawater, and more generally that the gill microbial community differ markedly from the seawater one. Our results open new perspectives for research on fish health and diseases and for the cultivation of fish-gill-associated bacteria.
Abstract 176
Are openly available AI tools useful for shark genus identification? A case study in Tanzania
by Dominic Wrieden | Fridolin Haag | Arjun Chennu
Leibniz Centre for Tropical Marine Research (ZMT) | Leibniz Centre for Tropical Marine Research (ZMT) | Leibniz Centre for Tropical Marine Research (ZMT)
Sharks play a crucial ecological role in marine systems as keystone species, controlling ecological communities from the top-down. Out of the 536 shark species, 138 are classified as threatened, and fisheries are a major contributor, with an estimated mortality of about 100 million sharks each year. Monitoring these species is vital for their conservation, but visual identification is time-consuming due to the variety and similarities among species.
Machine learning techniques, such as deep neural networks (DNN), can assist in the identification of caught sharks from colored images, supporting monitoring personnel. To assess the feasibility of this approach, we used images of 985 caught sharks from the Wildlife Conservation Society (WCS) in Tanzania. These images represented 33 different species and 19 different genera. We compared the performance of four open available machine learning models in identifying sharks at the genus level. The default performance of these models was poor to moderate, with accuracies ranging from 33% to 65%, despite not being specifically trained for the shark genera found in Tanzanian waters.
To improve performance, we narrowed down the shark genera to those found in the region and focused on the six most common genera, which accounted for approximately 95% of all specimens and we were able to improve their performance, achieving an accuracy of 73%. While these results are still insufficient for real-world ecosystem management applications, they demonstrate the capability of identifying sharks from images. This emphasizes the need for region-specific solutions in different bio-geographical regions, with a future improvement towards specie level identification.
Abstract 178
Bioremediation in marine RAS: testing Ulva sp. for its capacities as a filter for toxic ozonation by-products in an experimental outdoor aquaculture system
by Sabine Weidlich | Clara Priemer | Aschwin Engelen | Andreas Kunzmann
ZMT Bremen | Department of Functional and Evolutionary Ecology, University of Vienna | Marine Ecology and Evolution Research Group, Centro de Ciencias do Mar, Universidade do Algarve | ZMT Bremen
The maintenance of good water quality in recirculating aquaculture systems (RAS) is crucial for the production success in these emerging systems. Ozone (O3) has seen an increase in interest among aquafarmers worldwide as a water treatment tool with a wide array of beneficial effects. Besides its germicidal properties, ozone can enhance solid removal, degrade off-flavour producing molecules, oxidise toxic nitrogen compounds, and even act on submerged microbial biofilms, which are known to act as refugia for pathogens. While its application in freshwater is mostly unproblematic, ozonation of marine water creates secondary oxidants due to the oxidation of naturally occurring bromide-ions (Br-). These by- products of ozonation are termed ‘ozone-produced oxidants’ (OPO) and they can be detrimental to animal health if certain threshold levels are exceeded. In this experiment, we tested the marine seaweed Ulva sp. for its bioremediation properties regarding OPO in an outdoor IMTA (Integrated Multi-Trophic Aquaculture)-RAS-setup growing Gilthead seabream (Sparus aurata). Seawater from the fish tanks was ozonated and subsequently lead through an Ulva cultivation unit. OPO concentrations in the water were measured before and after flowing through the seaweed tank and the decline compared to controls without Ulva. Additionally, the impacts of OPO on growth, composition and photosynthetic activity in Ulva was investigated by comparing OPO-exposed seaweed to controls cultivated without ozonation. While a reduction of OPO concentrations could be shown for RAS containing seaweed, ozonation caused diminished growth, slightly lower fluorescence signals, change in morphology and a shift in amino acid contents in Ulva.
Abstract 179
Amplicon sequencing using the portable Oxford Nanopore MinION for fish DNA reference database: a fast, reliable and promising approach
by Cretus Mtonga | Achim Meyer | Oscar Puebla
The Leibniz Center for Tropical Marine Research (ZMT) | The Leibniz Center for Tropical Marine Research (ZMT) | The Leibniz Center for Tropical Marine Research (ZMT)
Tanzania hosts fish diversity in the coral reefs and seagrasses that are threatened by overfishing, calling a need for effective and rapid monitoring. Application of molecular techniques enables biodiversity assessment through environmental DNA applications. Unfortunately, in developing countries there are incomplete reference databases and no readily available sequencing services. We used the portable Oxford Nanopore’s MinION Sequencing device to analyse 190 fishes from Tanzania (with reference photographs). In addition to the standard COI based identification, we employed a novel approach to amplify two variable regions of the 12S gene in one PCR product covering the fragments recommended for eDNA studies.
We successfully amplified about 670bp of the 12S region (“miFish” and “teleo”) across a broad range of fish taxa and sequenced at the ZMT-Biolab. Amplification success of this novel 12S fragment was higher as in COI. For the 655bp COI fragment we obtained 131 high quality barcodes of 665bp (+24 low quality barcodes) giving 117 exact BLAST matches within the OTU threshold (identity >= 99%, query Coverage >= 80%) and 14 close matches (94-98% identity) by BLAST searches. Close matches were from Perciformes, Beloniformes and Clupeiformes, indicating species lacking reference sequences. For 12S we gained 171 valid barcodes with length 661-741bp (mean 670bp). Only 58% of the barcodes revealed >99% identity, 67 close match (90-99% identity), 4 weak match (<90% identity), highlighting the importance of generating a regional reference database in advance of eDNA metabarcoding.
Using the protocol from DNA extraction to sequence data can take up to two days, and with further experience one day can be possible. In conclusion, the portable and affordable MinION Sequencing provided comparable results to the traditional sanger sequencing method. These promising results suggest that the device can be adapted by managers to rapidly uncover biodiversity for protection and sustainability.
Abstract 182
Cancelled
Participatory modelling and stakeholder engagement for ecosystem-based fisheries management
by Giovanni Romagnoni
Leibniz Center for Tropical Marine Research
Ecopath with Ecosim is a highly versatile ecosystem modelling framework, and proves itself to be valuable for interacting with stakeholders at multiple levels. Several applications exist, covering, among the others, participatory modelling, and co-development of scenarios.
Here, we present a case study of stakeholder engagement using an Ecopath with Ecosim model for investigating adaptation strategies of the fishery sector, and their projected efficacy under local changes in the socio-ecological system. This example focuses on the artisanal offshore fisheries for Humboldt squid (jigging) and mahi-mahi (longline) in Paita, Northern Peru. An Ecopath with Ecosim model was used as a leverage tool to understand the perceived main challenges and existing or plausible adaptation strategies in the face of past or hypothetical future factors of change across ecological, environmental, and social realms in this particular fishing sector. A series of focus group exercises during consultation workshops allowed participants to express their perceptions and experiences. Guided discussions with scientists allowed to effectively translate users’ experience, perspective and expectations into a quantitative framework. Next, the ecosystem model was used to project plausible effects for the fisheries under the user-proposed changes in the system, and to evaluate how the proposed adaptation strategies would perform under such scenarios of change.
This exercise shows how the model can be applied to elicit stakeholders’ responses, and how it can incorporate stakeholder-proposed scenarios, in this particular case focusing on the evaluation of past adaptation strategies to changes in the system, and to gauge their robustness to plausible future changes in the ecosystem under the constraints of the ecosystem model. Future steps, with refinement of adaptation strategies under more realistic global change scenarios, could guide management choices based on stakeholders’ preferences, facilitating a participatory process in the management decisions based on the information collected on the field.
Abstract 185
Governing marine protected areas for harbour porpoise conservation in the German North Sea
by Wiebke Homes
Leibniz Zentrum für Marine Tropenforschung, Bremen
Marine ecosystems and biodiversity are embedded in complex socio-ecological systems and in the North Sea, they are under extreme anthropogenic pressure from cumulative uses such as fishing, offshore windfarms, maritime transportation and resource extraction leading to habitat destruction. The increasing industrialisation of the North Sea profoundly changes environmental conditions and challenges current processes of marine spatial planning. This results in trade-offs between conservation and use, and particularly impacts marine predators with migratory routes. Although special protection in the form of protected areas is in place for the only endemic whale species in the North Sea, the harbour porpoise (Phocoena phocoena), its abundance is declining and their distribution shifting, which necessitates a transformative shift towards more effective governance arrangements. As a first step, this research therefore assesses current governance structures in the marine protected areas (MPAs) Sylt Outer Reef and the Whale Sanctuary in the German North Sea using the MPA Governance framework by Jones. Semi-structures interviews that have started in September 2023 and are still ongoing investigate the mechanisms of a diverse range of economic, legal, communication, knowledge and participation incentives. It was already found that the two MPAs vary in the set-up of their institutional structures and processes. They employ a similar set of incentives such as having to follow hierarchical obligations and having in place collaborative platforms for stakeholders. However, both MPAs lack control and sanctioning when rules are not complied with, and seem to fail to effectively protect harbour porpoises. This study contributes to the wider academic debate on how to best shape effective marine predator conservation for an adaptive ecosystem- based management.
Abstract 190
Impact of light- and UV-stress on lipid peroxidation and photosynthesis of the three edible macroalgae Caulerpa lentillifera, Botryocladia botryoides and Codium edule
by Kira Kaul
student
The two green edible macroalgae Caulerpa lentillifera and Codium edule as well as new candidates like the red macroalga Botryocladia botryoides are highly requested as human food source. To cope with the increasing demand, it is beneficial to establish multilayer land-based aquaculture indoor systems for co-cultivation as a space-saving and efficiency improving solution.
The present study was conducted to investigate the impact of light- and UV-stress on relative growth rate (RGR), photosynthetic efficiency (Fv/Fm), lipid peroxidation (LPO) and the activity of the electron transport system (ETS) in the three edible macroalgae mentioned. Over an experimental run of up to 28 days, four different light treatments (50, 300, 500 μmol photons m−2 s−1 and 50 μmol photons m−2 s−1 with additional UV- A radiation) were tested in an indoor cultivation experiment.
Results showed that C. lentillifera and B. botryoides revealed highest RGR and Fv/Fm values in the low light treatment 50 μmol photons m−2 s−1 + UV, as well as lowest LPO activities were detected. Moreover, B. botryoides showed almost similar response in the low light treatments, while for both algae 300 and 500 μmol photons m−2 s−1 negatively impacted their physiological condition. In C. edule none of the tested treatments indicated a significant impact on RGR, Fv/Fm, LPO, and ETS. However, irradiances between 50 and 300 μmol photons m−2 s−1 are suggested. Hence, C. edule has a potential to be cultivated under higher light irradiances than the other two tested macroalgae.
Therefore, it is recommended to place C. edule in the upper level of a potential multilayer system, while C. lentillifera and B. botryoides should be cultured in the level below. However, long-term effects on the physiological condition have to be examined.