Scientific background document in support of the development of a CCAMLR MPA in the Weddell Sea (Antarctica) – Version 2017 – Reflection of the recommendations by WG-EMM-16 and SC-CAMLRXXXV

The CAMLR Scientific Committee in 2016 reviewed three scientific background documents in support of the development of a CCAMLR MPA in the Weddell Sea. Germany was asked to carry out further work, in particular regarding the issues and questions raised at WG-EMM-16 and SC-CAMLR-XXXV. Here, the authors intend to update the CCAMLR Working Groups on the current state of the work carried out during the 2016/2017 intersessional period. Chapter 1 of this working group paper informs on the new data retrieval process. Chapter 2 presents the updated analyses of relevant data layers, including an update on the Antarctic toothfish habitat model. Chapter 3 provides a sensitivity analysis of the level of protection for Antarctic toothfish and other demersal fish that explores a range of protection-level scenarios. In this context, we show how the cost layer works. Subsequently, a revised Marxan approach based on the updated data layer is shown. In Chapter 4 we outline the way we transferred the results of the scientific analyses into the WSMPA borders and management zones

Scientific background document in support of the development of a CCAMLR MPA in the Weddell Sea (Antarctica) ? Version 2016 -Part B: Description of available spatial data-

The authors present to the Working Group on Ecosystem Monitoring and Management (WG EMM) the scientific background and justification for the development of a marine protected area (MPA) in the Weddell Sea planning area. In accordance with the recommendations by WG-EMM-14 (SC-CAMLR-XXIII, Annex 6), this was done in three separate documents (Part A-C). WG-EMM-16/01 (Part A) sets out the general context of the establishment of CCAMLR-MPAs and provides the background information on the Weddell Sea MPA (WSMPA) planning area; WG-EMM-16/02 (Part B) informs on the data retrieval process and WG-EMM-16/03 (Part C) describes the methods and the results of the scientific analyses as well as the development of the objectives and finally of the borders for the WSMPA. Earlier versions of Parts A-C were already presented at the meetings of EMM and SC- CAMLR in 2015. The Scientific Committee did recognise that the body of science of the background documents (SC-CAMLR-XXXIV/BG/15, BG/16, BG/17) provides the necessary foundation for developing a WSMPA proposal (SC-CAMLR-XXXIV, § 5.11). Here, the authors present to WG EMM the final version of Part B that provides a systematic overview of the environmental (chapter 1) and ecological data sets (chapter 2) acquired for the WSMPA planning. Part B has been further revised in the light of comments received at the above mentioned meetings and in the 2015/16 intersessional period. Some data sets were newly acquired (e.g. data on seabirds, demersal fish) and final editorial changes were done

Zoobenthic fauna distribution in an Antarctic fjord area under glacier retreat

The West Antarctic Peninsula faces a significant increase in temperature and anthropogenic carbon emissions, affecting its marine and terrestrial biodiversity. Species Distribution Models (SDMs) are essential tools for assessing habitat suitability and predicting the responses to these changing conditions. In the coastal fjord ecosystem Potter Cove, glacier retreat exposed new ice-free areas altering the environment through meltwater input and sediment runoff. This research aims to identify the environmental drivers influencing the distribution of Antarctic zoobenthos in this changing coastal ecosystem and to analyze potential zoobenthic assemblage compositions in areas strongly affected by glacier retreat. Analysis of eight benthic taxa distributions reveals distinct habitat types within a maximum range of approximately 1.5 km. About 60% of the study area (equivalent to 5.45 km2) is estimated to be suitable for zoobenthic occurrence. Interpretation of binary transformation thresholds highlights taxa-specific environmental preferences, where lower values correspond to broader habitat extensions, suggesting potential coexistence in glacier-influenced areas. This study emphasizes the significance of interdisciplinary approaches in understanding benthic responses to climate change in the Antarctic coastal ecosystem. It highlights the necessity for ongoing long-term research and the development of conservation and management strategies to address the continuing environmental shifts effectively

Exploring spatial similarity and performance among marine protected area planning scenarios: The case of the Weddell Sea, Antarctica

The world's oceans are exposed to a variety of pressures, such as overfishing and the environmental effects of increasingly dense coastal populations. Policy and science agree that a global network of marine protected areas (MPAs) will mitigate these effects. Conservation planners face the dual challenge of planning MPAs based on complex scientific information and supporting the decision-making process through clear and transparent communication with the involved stakeholders. To this end, visual comparisons of different mapped reserve configurations are a commonly used approach, while analytical approaches that assess the efficiency of different planning scenarios and trade-offs among them are still rarely used in practice. Here, we use uni- and multivariate statistics to compare reserve configurations used in the process of designing a Weddell Sea MPA (WSMPA) in Antarctica. We show that different target level settings (low, medium, mixed) for conservation features affect the configuration of the solutions significantly. The mixed-target scenario was one of the most flexible ones in that it produced the most diverse set of solutions, providing several options for consideration. At the same time, it was also the most well balanced scenario, finding relatively cost-efficient solutions while selecting an intermediate number of planning units that were most spatially clustered. Our study complements the qualitative sensitivity analysis carried out previously (mainly visual, descriptive scenario comparisons) and will hopefully further advance the WSMPA development process under CCAMLR. Furthermore, this paper adds to the growing literature advocating the application of multivariate statistics for further thorough and systematic evaluation procedures in conservation planning

Hierarchical Modelling of Species Communities (HMSC) of benthic species, Potter Cove, King George Island, Antarctica

Understanding the distribution and coexistence patterns of (benthic) species in Antarctic ecosystems is crucial for the estimation of present and future carbon turnover, ecosystem management, and conservation. Spatial and predictive modeling of environmental and biological data becomes more and more important at remote places to understand and to observe the ecological response to global climate change. In our study, we use the Hierarchical Modelling of Species Communities (HMSC) to model the distribution and coexistence of benthic species based on ecological data. The approach implements a Bayesian framework with Gibbs 'Markov chain Monte Carlo' sampling, and enables to assess the influence of phylogenetic information on species distribution patterns. The HMSC at Potter Cove, West Antarctic Peninsula (WAP), includes a variety of environmental variables, such as water temperature, salinity, bathymetry, distance to the glacier, sediment grain size, suspended particulate matter, and current velocity, among others. As a result, we present habitats for selected benthic communities in prediction maps, and we provide the species composition and spatial variability within the study area. We identify the environmental variables with the highest impact on the benthic community distribution, pinpointing the critical ecological factors in times of climate change. And we learn about the species coexistence patterns, the role of species interactions, and phylogenetic relationships in shaping community structures. The application of HMSC at Potter Cove contributes to the estimation of coastal blue carbon at the WAP, and thus to better coastal conservation planning for Polar regions

Data analysis

The authors present to the Working Group on Ecosystem Monitoring and Management (WG EMM) the scientific background and justification for the development of a marine protected area (MPA) in the Weddell Sea planning area. In accordance with the recommendations by WG-EMM-14 (SC-CAMLR-XXIII, Annex 6), this was done in three separate documents (Part A-C). WG-EMM-16/01 (Part A) sets out the general context of the establishment of CCAMLR-MPAs and provides the background information on the Weddell Sea MPA (WSMPA) planning area; WG-EMM-16/02 (Part B) informs on the data retrieval process and WG-EMM-16/03 (Part C) describes the methods and the results of the scientific analyses as well as the development of the objectives and finally of the borders for the WSMPA. Earlier versions of Parts A-C were already presented at the meetings of EMM and SC-CAMLR in 2015. The Scientific Committee did recognise that the body of science of the background documents (SC-CAMLR-XXXIV/BG/15, BG/16, BG/17) provides the necessary foundation for developing a WSMPA proposal (SC-CAMLR-XXXIV, § 5.11). Here, the authors present the final version of Part C to WG EMM. Part C has been further revised in the light of comments received at the above mentioned meetings and in the 2015/16 intersessional period. The text has also undergone final editorial corrections. Chapter 1 shows a revision of the data analysis including, for example, newly analysed data layers on seabirds and demersal fish. Chapter 2 provides an update of the newly conducted MPA scenario development incorporating a cost layer analysis

Predicting fishing ground accessibility in the Antarctic Weddell Sea

Sea ice is a major constraint of fishery performance in the Southern Ocean seasonal sea ice zone. We use sea ice concentration data from 2002-2017 that cover the wider Weddell Sea to establish statistical models of (i) accessibility, i.e. the probability that a particular area is navigable by fishery vessels at a given time, and of (ii) repeated accessibility, i.e. the probability that a particular area is navigable by fishery vessels at a given time and again within the following two years, as requested by CCAMLR research fishery regulations. Our findings indicate that under the actual sea ice conditions almost 50% of the entire WSMPA Planning Area is not suitable for fishery vessels at any time of the year, while there are high spatiotemporal variability in repeated accessibility in particular areas such as along the ice shelf of the eastern and south-eastern Weddell Sea. We consider our models to constitute valuable, riskreducing planning tools in the further development of fishery research as well as of ship-bound tourism in the wider Weddell Sea area

Scientific background document in support of the development of a CCAMLR MPA in the Weddell Sea (Antarctica) – Version 2018 – Reflection on the recommendations by WG-EMM-17 and SC-CAMLRXXXVI

The CAMLR Scientific Committee in 2017 reviewed the scientific background document SC-CAMLRXXXVI/ BG/28. Germany was asked to carry out further work, in particular as regards the issues and questions raised at WG-EMM-17 and SC-CAMLR-XXXVI with respect to the WSMPA proposal (SCCAMLR- XXXVI, Annex 6, §§ 5.1-5.14). Chapter 1 reflects on the recommendations concerning the suitability of some data layers for Marxan analyses, such as the data layer representing the distribution of Antarctic krill larvae (SC-CAMLRXXXVI, Annex 6, §§ 5.9 - 5.10). Chapter 2 discusses the recommendations concerning the suitability of the cost layer developed for the WSMPA Marxan analysis (SC-CAMLR-XXXVI, Annex 6, §§ 5.10 and 5.12) and presents the updated cost layer. Chapter 3 provides a new data layer on juvenile Antarctic toothfish, and Chapter 4 presents a robustness testing of the WSMPA Marxan model

Weddell Sea MPA data layers have been deposited with the data publisher PANGAEA

This paper informs EMM 2019 about the data layer products, which were developed for WSMPA spatial planning, and lists the DOIs to the respective PANGAEA entries. By depositing these data layers with PANGAEA, we provide transparency regarding the WSMPA development process and follow the discussion under CCAMLR about the need to make reference material on MPAs easily accessible to the scientific community