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

Data on benthic species assemblages and seafloor sediment characteristics in an offshore windfarm in the southeastern North Sea

The German Bight (North Sea) is a centre of development of offshore wind energy. In the near future, windfarms will cover a significant part (about 25%) of the German Exclusive Economic Zone. In order to understand and assess potential effects of the construction and early operational phase of offshore wind turbines on the marine environment, an extensive research programme was carried out at Germany's first offshore windfarm alpha ventus. Here, data are presented on macroinfauna and local sediment characteristics collected as part of this programme. Grab samples were taken annually in autumn in 2008 (baseline), 2009 (construction phase) and 2010 and 2011 (early operational phase). Sampling stations were located along transects between adjacent turbines inside the windfarm and in two reference areas with similar environmental conditions in terms of sediment characteristics and water depth. A total of 336 samples were taken inside the windfarm and 192 samples in the reference areas. Sediment characteristics were described in terms of grain size distribution and organic content. The infauna was taxonomically analysed and quantified in terms of abundance and biomass. One-hundred three infauna taxa were identified, mainly belonging to the polychaetes, crustaceans and bivalves, living in fine to medium sandy soft bottom in water depths ranging from -27 m to -30 m. The data can be useful in meta-analyses of renewable energies impacts. Additionally, the data can support species distribution modelling to gain a better understanding of species' requirements and habitats as a basis for spatial planning scenarios and the evaluation of the ecological status of the marine environment. Moreover, the data can serve as baseline data for future monitoring and management of nearby protected areas where environmental conditions are comparable to those of the present study area

Colonisation success of introduced oysters is driven by wave-related exposure

The Pacific oyster, Magallana gigas, is an extremely successful invader with established populations in marine and estuarine habitats almost all over the world. Ecological implications of the introduction of this species to indigenous communities are well documented. However, the processes by which this species successfully establishes in a recipient community is still insufficiently understood. The early detection of the oyster at the island of Helgoland (North Sea) provided the ideal opportunity to investigate whether physical mechanisms, such as wave exposure, influence their successful colonisation. We hypothesized that oyster colonisation benefits from wave-protected conditions. For this purpose, we evaluated colonisation success of M. gigas among wave-protected sites and wave-exposed sites along the island’s pier system. The densities of M. gigas were significantly higher at wave-protected sites than at wave-exposed sites, and the frequency distributions of oyster lengths indicated better growth and higher survival rates in the harbours. This higher colonisation success at wave-protected sites may be explained by the relative retention time of water masses in the harbours, probably resulting in both reduced larval drift and lower energy demands for secretion formation (i.e. firmer binding to the substrate). The fact that the density of M. gigas can vary greatly on small spatial scales depending on exposure corroborates a multiple exposure sampling approach to monitor oyster populations in order to avoid potential overestimations of population sizes in given areas

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

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

Icefish spawning aggregation in the southern Weddell Sea

During the Continental Shelf Multidisciplinary Flux Study (COSMUS) expedition from February to March 2021 aboard RV Polarstern (expedition ID: PS124) (Hellmer & Holtappels, 2021), a large spawning aggregation of notothenioid icefish (Neopagetopsis ionah, Nybelin 1947) was discovered in the southern Weddell Sea. The CCAMLR community was informed of this discovery by Germany in COMM CIRC 22/10 and SC CIRC 22/08 earlier this year (17 January 2022). Purser et al. (2022) report on the spawning aggregation in Current Biology. Here we provide detailed information on the active fish nest aggregation and on additional icefish nesting sites observed in the Filchner Trough area (Knust & Schröder, 2014; Schröder, 2016; Riginella et al., 2021; Purser et al., 2022; Purser et al., in review)

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

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