Abstracts PA1

Towards sustainability in managing aquatic resources: Multiple management approaches for complex social-ecological systems



Abstract 146

Integrated Monitoring of Fish Abundance using Combined Tools (IMFACT) & Managing sustainable sea URchin fishery and marine FORest conservation (MUrFor)

by Giovanni Romagnoni |

ZMT- WG Resource Management

Visual census, used to monitor fish abundance in MPAs and coastal areas, presents some limitations and biases. In a recently developed project proposal, we propose to complement traditional visual census with an integrated toolbox composed of a Remotely Operated Vehicle (ROV) and a hydroacoustic array. These are non-invasive, low-cost and practical tools, suitable for monitoring fish abundance in coastal areas and MPAS. The combination of visual and acoustic sensors can cover wide areas and detect mobile species. Our toolbox could thus enable MPA managers and scientists to monitor fish abundance and biodiversity more accurately and manage fisheries more sustainably. We provide the rationale, potential and steps for development.

The MUrFor project focuses on the sustainable management of sea urchin fishery and on the interplay between resource use, ecosystem dynamics and habitat conservation for the tri-trophic system fish-sea urchins-macroalgae. Overfishing may indirectly impact Macroalgal forests, as the reduction of predatory fish results in loss of predator control on herbivores (e.g., sea urchins), permitting their uncontrolled proliferation with loss of habitat structure as consequence of the overgrazing. In the Mediterranean sea, both sea urchins and fish constitute important target species for small-scale fisheries. Uncoordinated management resulted in overfishing of either or both resources, and/or in overgrazing of the macroalgae, leading to biodiversity loss and to permanent regime shifts.
The MUrFor project sets out to improve understanding of coastal ecosystem dynamics and their relationship to environmental stressors in the context of multiple alternative stable states. The objective is to identify thresholds leading to irreversible regime shifts on the resource (i.e. overfishing), on the habitat (i.e. overgrazing) and on the fishery (i.e. economic sustainability). This will be achieved through a multi-modelling approach based on a suite of single-species, multi-species, ecosystem, economic and bioeconomic models, which allow accounting for multispecies dynamics, socio-economic considerations and stakeholder’s preferences.


Abstract 135

Enzymatic capacity of copepod Apocyclops panamensis to biosynthesis of LC-PUFA

by Sofia Afoncheva | Alberto Ribes-Navarro | Juan Carlos Navarro | Naoki Kabeya | Andreas Kunzmann & Oscar Monroig |

ZMT | Instituto de Acuicultura Torre de la Sal (IATS-CSIC), Spain | IATS-CSIC, Spain | Tokyo University of Marine Science and Technology, Japan | ZMT | IATS-CSIC, Spain

Apocyclops panamensis is a cyclopoid copepod that has high potential as live feed in aquaculture. Nutritional quality of live feed is determined primarily by its fatty acid (FA) profile, FA absolute content, and the amount of long-chain polyunsaturated FA (LC-PUFA), particularly of omega-3 (ω3) LC-PUFA. Earlier it was assumed that only algae, bacteria and some protists can produce ω3 LC-PUFA. However, it was recently demonstrated that a large variety of marine invertebrates possess genes that enable them to produce ω3 LC-PUFA de novo (Kabeya et al., 2018).

Our goal was to identify whether A. panamensis owns the potential ability to biosynthesise ω3 LC-PUFA. We performed the molecular and functional characterization of genes encoding fatty acyl desaturases and elongases that determine the LC-PUFA biosynthesis in A. panamensis.

We identified two methyl-end (ωx) desaturases, two front-end desaturases and six fatty acyl elongases genes in A. panamensis. The functional characterisation of the genes was performed in yeast (Saccharomyces cerevisiae) by expressing their coding region and growing the transgenic yeast in the presence of potential PUFA substrates for either desaturases or elongases.

Collectively, analysis of A. panamensis gene activity showed that this copepod has a complete enzymatic machinery enabling this copepod to biosynthesise LC-PUFA. Thus A. panamensis can contribute to primary production of ω3 LC-PUFA, which makes it a valuable and promising nutritional component of fish larvae diet in aquaculture.



Abstract 132

Mapping stakeholders and their discourses using Social Network Analysis and Q methodology: An investigation of sea turtle management in Sri Lanka

by Maheshwaran Govender | Meenakshi Poti | T.W.G.F. Mafaziya Nijamdeen | K.A. Sunanda Kodikara | Jean Hugé | Farid Dahdouh-Guebas |

Systems Ecology and Resource Management Research Unit (SERM), Department of Organism Biology, Université Libre de Bruxelles – ULB, Av. F.D. Roosevelt 50, CPi 264/1, Brussels, 1050, Belgium | Systems Ecology and Resource Management Research Unit (SERM), Department of Organism Biology, Université Libre de Bruxelles – ULB, Av. F.D. Roosevelt 50, CPi 264/1, Brussels, 1050, Belgium | Systems Ecology and Resource Management Research Unit (SERM), Department of Organism Biology, Université Libre de Bruxelles – ULB, Av. F.D. Roosevelt 50, CPi 264/1, Brussels, 1050, Belgium | Department of Botany, Faculty of Science, University of Ruhuna, Matara, Sri Lanka | Department of Environmental Sciences, Open University of the Netherlands, Valkenburgerweg 177, Heerlen, 6419AT, the Netherlands | Systems Ecology and Resource Management Research Unit (SERM), Department of Organism Biology, Université Libre de Bruxelles – ULB, Av. F.D. Roosevelt 50, CPi 264/1, Brussels, 1050, Belgium

The beaches of southern and southwestern Sri Lanka are important nesting grounds for five sea turtle species. Threats such as turtle shell trade, egg and meat consumption, and fisheries-related bycatch have caused declines in the nesting population. The existing conservation approaches depend on sea turtle tourism for financial support. This has resulted in a complex social-ecological system (SES) comprising diverse stakeholders. Our study investigates the human component of this SES by integrating two stakeholder-based approaches to understand the challenges in sea turtle conservation in the region. We use Social Network Analysis (SNA) to identify the key stakeholders and map their collaborative relationship, and Q methodology (Q) to understand their discourses regarding sea turtle management. Through SNA we have identified 39 stakeholders amongst which three stakeholders hold a central position in the network. Using Q, we identify three distinct discourses highlighting the preferred conservation approaches and challenges related to sea turtle management in Sri Lanka. We observe a polarization in discourses 1 and 2 suggesting an ongoing dilemma between the in-situ and ex-situ conservation of sea turtles in the region. However, there is a collective call to promote in-situ conservation with community participation. The network mapping also indicates that there is a weak sectoral collaboration within the governmental departments and increased privatisation in the sea turtle management network. Subsequently, discourse 3 highlights that poor governance and unregulated private sea turtle hatcheries are major concerns for sea turtle conservation. Our analysis of the social network and perceptions has revealed the necessity for improved governance and better management strategies for effective and sustained sea turtle conservation and tourism in Sri Lanka. This methodological approach of combining SNA and Q is applicable to study stakeholders and their discourses across diverse SES to inform decision-making and enhance conservation output.


Abstract 131

Spatio-temporal diversity in German brown shrimp fishery

by Serra Örey | Oscar Puebla |

Hochschule Bremerhaven & ZMT | ZMT

Understanding the diversity of human behavior is crucial for the better management of any socio-ecological system. Knowing more about how fishers operate could help to optimize management measures as well as quantify the extent of environmental impact. Thus, we investigate spatial and temporal patterns in vessel movement data of one métier in the southern North Sea. In the EU, since 2005, every fishing vessel over 15m in length (over 12m since 2012) is required to have a vessel monitoring system (VMS) on board. With the help of this satellite-based technology, the movement of individual fishing vessels can be understood and analyzed in high spatial resolution. For our study, we focused on the German North Sea brown shrimp fishery, which is currently under high economic pressure due to increasing fuel costs and decreasing shrimp prices. Understanding individual fishing behaviors could help to quantify which resource use strategy benefits long-term business success. Vessels were clustered using temporal and spatial parameters that were independent of the spatial location as well as their respective interannual variation. Subsequently, differences between groups both in economic terms and according to their spatial footprint were analyzed. In perspective, the results can be used in an agent-based bio-economic fleet model, for testing the economic viability of different strategies in various future scenarios.


Abstract 129

Current trends and suggested future directions in coral transplantation for reef restoration

by Sebastian C.A. Ferse | Lena Rölfer | Margaux Hein 

Leibniz Centre for Tropical Marine Research (ZMT) | Faculty of Sustainability, Leuphana University; Climate Service Center Germany (GERICS), Helmholtz- Zentrum Hereon | Marine Ecosystem Restoration (MER) Research and Consulting

Coral transplantation has been used in reef restoration for decades, but information on projects is mostly limited to published scientific studies and technical reports. Many practitioners do not have the capacity to share their progress in peer-reviewed literature, yet likely have a wealth of information on how to improve transplantation efforts. To gain an overview of these projects, we conducted an initial systematic online survey of projects run by various practitioners, covering most of the tropical belt and ranging in size from a few hundred to >5000 transplants. The most frequent source of coral fragments were already- broken corals. The use of sexual reproduction was very limited. Fast-growing, branching corals were by far the most common transplanted growth form. About half of the projects mentioned undertaking maintenance. The majority of projects undertook subsequent monitoring, yet available data indicates that duration of monitoring efforts was not adequate to evaluate long-term success. The findings underline that while some general principles for successful coral restoration projects are reasonably well established, others need to be mainstreamed better to improve coral transplantation effectiveness for reef restoration. This relates in particular to sustainable funding, adequate site assessment, and long-term monitoring using established protocols. Additional information is needed to better understand and address potential challenges with regards to the sourcing of transplants and use of slow-growing species. The results underline a need to develop and use monitoring protocols that allow gauging and comparing the effectiveness of coral transplantation among projects, as well as for accessible platforms to allow the exchange of experiences made in different projects. Regular surveys of projects are recommended to collate and share information among practitioners. Important future directions include a better integration of local communities in the design of reef restoration projects and the use of social-ecological indicators to monitor progress and gauge success.


Abstract 127

Application of the of environmental DNA (eDNA) technique in monitoring of Tanzanian fishes

by Cretus Mtonga | The Leibniz Center for Tropical Marine Research (ZMT)

Notwithstanding the increased biodiversity loss overtime, monitoring of fish is essential for conservation and sustainable fishery management. But assessment of fish diversity in the Western Indian Ocean (WIO) region in particular relied mostly on the traditional visual census technique. This method has proven to be not reliable as it requires an extensive expertise in fish identification and in most cases overlooked cryptobenthic, pelagic fish that swim over the diver and fish larvae. In this study we aim to compare the efficiency of the environmental DNA (eDNA) technique against the visual census method in detecting fish species at the Mafia archipelago. A series of water samples were collected from a total of 10 sites with varying habitat composition (seagrasses, coral reefs and macroalgae), subjected to filtration, DNA extraction and metabarcoding. To have a good comparison of the methods, snorkeling was accomplished concurrently at the study sites. Several species were identified using visual census, and metabarcoding is underway to affirm the observed diversity. The barcoding of species was conducted to construct the library where COI and 12S teleo fragments of mitochondria DNA were sequenced, results are presented. This is a very first research in the WIO region that assess the utility of the eDNA technique in biomonitoring of Tanzania fishes.

Abstract 124

Jellyfish Cassiopea andromeda: A treasure trove of pharmacologically active compounds

by Rima Beesoo | Holger Kühnhold | Matthias Y. Kellermann | Peter J. Schupp | Andreas Kunzmann |

Leibniz Center for Tropical Marine Research (ZMT), Fahrenheitstr. 6, 28359 Bremen, Germany Institute of Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, 26111 Oldenburg, Germany | Leibniz Center for Tropical Marine Research (ZMT), Fahrenheitstr. 6, 28359 Bremen, Germany | Institute of Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, 26111 Oldenburg, Germany | Institute of Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, 26111 Oldenburg, Germany | Leibniz Center for Tropical Marine Research (ZMT), Fahrenheitstr. 6, 28359 Bremen, Germany

Jellyfish are widely known in Chinese cuisine, with some species recognised for their high nutritional value, as well as in traditional Chinese medicine. However, their health impact has not yet been adequately investigated. Recently, a greater emphasis has been placed on the link between oxidative stress, the pathogenesis of cancer, and their prevention by antioxidant-rich diets. Hence, by increasing scientific knowledge about jellyfish, we may catalyse their increased use as food supplements and nutraceuticals. In the present study, the jellyfish Cassiopea andromeda was exposed to multiple stressors such as varying temperatures and light intensities. The chemical components and bioactive properties of the jellyfish extracts are currently under investigation by detecting their in vitro antioxidant propensities, focusing particularly on observed changes in their metabolomic responses under various culture conditions. Preliminary findings show that extract from C. andromeda cultured under a combination of low temperature and high light intensity exhibited highest antioxidant by virtue of their superoxide and hydroxyl radical scavenging, ferric reducing and metal chelating activities. Their cytotoxic activity in cancer cells will be explored by assessing the effect of the extracts on target proteins involved in the complex signaling cascades of apoptosis including caspases, bcl-2, bax, cytochrome, p53, cyclooxygenase, lypoxygenase, mitogen-activated protein kinases. The bioactive extract (IC50 less than 30 ug mL-1) will be fractionated using preparative HPLC and the resulting sub- fractions will be bio-assayed. Further bioactive sub-fractions will be purified to obtain pure compounds. These compounds will be tested for their cytotoxicity and their structure will be determined by LC-MS, NMR spectroscopy, UV-vis and infrared spectroscopy. Our results may open a fertile area of research to pursue the search of bioactive agents. Furthermore, our study will also provide baseline scientific information on best and innovative practices for aquaculture and sustainable production of jellyfish biomass for use as prophylactics.

Graphical abstract

Abstract 130

Potential to integrate the economically important gastropod Babylonia areolata in pond cultures of Caulerpa lentillifera

by Beatrice Brix da Costa | Lara Stuthmann | Aaron Cordes | Andreas Kunzmann | Karin Springer |

University of Bremen, ZMT | ZMT | Hochschule Bremerhaven, ZMT | ZMT | University of Bremen

The edible green macroalga Caulerpa lentillifera (also known as sea grapes) is mainly cultivated in Southeast Asia, especially in Vietnam but is recently gaining increased popularity worldwide due to its nutritional benefits for humans. This study assessed the co- culture potential of sea grapes and spotted babylon snails (Babylonia areolata) and the effect of culture method (tray vs. sowing) on growth and physiology of C. lentillifera. Three different treatments (algae and snails together, algae and snails spatially separated, only algae) were assessed for growth, photosynthetic efficiency, and antioxidant activity of the macroalga. Additionally, growth and survival of the spotted babylon snails as well as water quality were evaluated over six weeks at the Institute of Oceanography in Nha Trang, Vietnam. Results showed a positive effect of the co-culture on the growth and the photosynthetic efficiency of C. lentillifera. Regarding the culture methods, growth was slightly higher in the tray cultures. Babylonia snails raised NOx and Phosphate concentrations compared to the control treatment without snails. Survival of the snails was 100 % in all treatments and growth was not affected by spatial separation from the seaweed. These findings are an important first step towards co-culture approaches of these economically important species in Vietnam, highlighting the beneficial effects of snails on the sea grapes. However, further research is required to investigate the applicability of this co-culture at larger scales.

Abstract 133

Using oxygen measurements as a tool to study photo- physiological capacities in endosymbiotic jellyfish (Cassiopea andromeda)

by Pradipta Das | Holger Kühnhold | Andreas Kunzmann |

ZMT Bremen | ZMT | ZMT

Increasing temperatures due to global warming and climate change may stress many marine species. In concurrence with the temperature rise, various anthropogenic stressors induce eutrophication, hypoxia, and chemical toxicity in marine ecosystems. However, the jellyfish outbreak commonly known as jellyfish bloom is one of the most reported events in the coastal areas. The endosymbiont jellyfish Cassiopea andromeda has expanded their population from the Red to the Mediterranean Sea. This study focused on the effect of different water temperatures and PAR stress on the photobiological capacity of C. andromeda. To estimate the response of the jellyfish, they were exposed to three different temperatures and two different irradiances, including UV-B radiation. Gross photosynthesis, respiration, symbiont density, pulsation rate, and biomarkers were evaluated. The photosynthesis of acclimatized jellyfish was measured with increasing light irradiance levels of from 100 to1400 μmol photons m-2s-1. Catalase activity (CAT), total proteins, carbohydrates and lipids were estimated to understand the cellular stress of C. andromeda. The gross photosynthesis rate was found significantly different in all treatments compared to the control. The respiration rate and pulsation rate were increased with the elevated temperatures and reduced at cold temperatures. The total lipid content for all treatments remained unchanged compared to the control. CAT activities were reduced in all treatments than the control except one The total protein and carbohydrate content were found increased to all treatments. This study confirms, the high photo plasticity of C. andromeda to elevated temperatures and low-light conditions whereas it is sensitive to lower temperatures and high-light irradiated conditions. The jellyfish became bleached at high- light irradiated treatments and reduced their photobiological capacity. That could be the reason for the thriving of the organisms in eutrophicated areas.

Abstract 134

Integration of Babylonia areolata into existing tidal ponds for the cultivation of Caulerpa lentillifera

by Aaron Cordes | Lara Elisabeth Stuthmann | Beatrice Brix da Costa | Andreas Kunzmann | Karin Springer |

Hochschule Bremerhaven | Leibniz Centre for Tropical Marine Research | Universität Bremen | Leibniz Centre for Tropical Marine Research | Universität Bremen

The edible green alga Caulerpa lentillifera (also known as sea grapes) is widely cultivated in the Khánh Hòa region of Vietnam. The macroalga enjoys great popularity due to its good taste and high concentration of nutrients and trace elements. Seaweed aquaculture represents a sustainable and long-term method of alternative food production in Southeast Asia and, in some cases, is already an important future source of income for local people.

The marine gastropod Babylonia areolata is also widely cultivated in the Southeast Asian region. These snails feed on trash fish and contain high amounts of amino acids, minerals, vitamins, and fatty acids.

Both organisms are traded as delicacies and can fetch high prices. Since both organisms are cultivated in tidal ponds and sea grapes rely on nutrients, especially nitrate, which is also released by the snails, a co-culture of the two organisms seems promising. In a field experiment, questions about sea grape growth, quality and quantity based on culture method and co-culture with snails were addressed.

Three treatments were tested and compared in 300-liter tanks at the Institute of Oceanography in Nha Trang, Vietnam. In one setup snails and sea grapes were cultivated together in the same tank sediment. In another setup snails were separated by a net. Only sea grapes were cultured as control. Growth data of sea grapes and snails as well as water samples for nutrient analysis were taken. Photosynthetic efficiency was measured using a portable pulse amplitude-modulated chlorophyll fluorometer to identify possible physiological stress. Preliminary results show a significantly higher relative growth rate (RGR) of sea grapes when cultivated together with snails. The survival rate of the snails was not affected by the sea grapes. Whether RGR differs between tray and sediment culture method, as well as data about the photosynthetic efficiency and possible physiological stress remain to be evaluated.

Abstract 137

Scalable analysis of shallow coral reef habitats using Artificial Intelligence

by Khishma Modoosoodun Nicolas |

Leibniz Centre for Tropical Marine Research (ZMT)

Coral reefs are the most diverse and productive marine ecosystems on the planet, providing habitats to hundred of thousand of species. A combination of local and global stressors has led to the deterioration of coral reef health worldwide in the last decades. Under such pressures, the distribution, abundance and survival of the coral reef ecosystem are drastically reduced. Habitat maps are critical for effective management of the marine environment. Map making can be very time-consuming, making it challenging to produce scalable maps to track environmental changes over time at a larger scale. Artificial Intelligence techniques hold the promise to automate part of the process and hence speed up map production. In this research work, we aim at producing accurate and scalable marine habitat maps using photogrammetry and by applying AI technique to explore the spatial complexity and community structural patterns of coral reefs in the Great Barrier Reef. The targeted results will be semantically segmented maps of coral reef habitats that could be useful to decision-makers and ecologists. These maps can help a variety of reef studies: to automatically detect corals, choose study sites for research and development, design sampling strategies, and modeling habitat suitability.

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