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Accurate assessments of ecosystem condition are needed to inform management processes such as systematic conservation planning and protected area expansion, marine spatial planning and other effective area‐based conservation measures. Yet measuring the condition of dynamic and often largely inaccessible marine ecosystems is extremely difficult and presents a global challenge.Broad‐scale cumulative impact assessments have been used in South Africa as a proxy for marine ecosystem condition in national assessments and reporting because the data are more readily available, and knowledge exists on the impacts of various human activities (or pressures) on marine ecosystems. While useful for national reporting, assessments based on in situ ecological data are also needed at finer scales relevant to management.Applying the HELCOM BEAT approach, this study used in situ ecological data to identify potential methods and indicators that can be applied in South Africa to conduct integrated ecosystem assessments and to assess the suitability of current cumulative impact assessments as a proxy for condition.Aggregated fish indicators demonstrated greater sensitivity to varying human pressures compared with benthic community indicators, with responsiveness differing by location. Notably, site‐level differences in empirical condition emerged that broad‐scale cumulative assessments often missed. The study thus highlighted the varying suitability of cumulative impact scores as proxies for condition, indicating their reliability for fish communities. However, this is also dependent on the pressure types included, the biotic indicators used and the area of focus.Conservation decisions based solely on cumulative impact scores could misrepresent the actual condition of the environment, which makes it difficult to make management decisions, especially at finer scales. As such, conservation initiatives need to be regionally adapted to effectively address the unique pressures and conditions of each area and should be tailored to account for fine‐scale variability, instead of adopting a one‐size‐fits‐all approach. [ABSTRACT FROM AUTHOR]

South Africa sought to implement an ecologically representative Marine Protected Area (MPA) network to achieve biodiversity and fisheries management goals with least impact on offshore stakeholders. The result was the declaration of a spatially efficient network representing 131 of 150 marine ecosystem types (87%) in 5.4% of ocean area. We outline the 15‐year process from planning to implementation of 20 new MPAs, including contentious areas recognized as important for conservation decades ago. Systematic Conservation Planning (SCP) supported by 532 data layers and an inclusive stakeholder process identified priority areas, reduced conflict and guided complex trade‐offs. Multiple scenarios and iterative improvements increased transparency, supported ocean zonation and achieved balanced compromises while maintaining conservation objectives. Key challenges, enabling factors and lessons are shared. We demonstrate that flexible, evidence‐based SCP together with adaptive social processes that are alert to opportunities can support implementation of representative MPA networks aligned to ocean economy goals. South Africa used systematic planning and inclusive stakeholder engagement to protect 87% of its 150 marine ecosystem types in just 5% ocean area [ABSTRACT FROM AUTHOR]

Systematic conservation planning (SCP) to design marine protected areas (MPAs) has traditionally focused on species distributions or benthic habitat features that drive the determination of conservation priorities. Pelagic ecosystem protection is usually incidental because these ecosystems are often data-poor and are difficult to visualize in a planning context. Pelagic ecosystems, however, face increasing and cumulative impacts from threats such as overfishing and climate change, and a precautionary approach is required to protect both known and unknown biodiversity patterns and ecosystem processes. Data-driven pelagic habitat classifications are important when planning for habitat protection in the absence of sufficient in-situ data. In this study, we describe a method for creating a bioregional map of the upper-mixed layer of South Africa's pelagic realm. We selected relevant variables and parameters that best reflect key ecosystem properties at broad, meso, and local scales. We conducted a hierarchal cluster analysis using open-access sea surface temperature (SST), chlorophyll- a (chl- a ), net primary productivity (NPP), mean sea level anomalies (MSLA), and seabed slope and depth data. The resulting map delineates three bioregions subdivided into seven biozones and sixteen pelagic habitats within South Africa's continental Exclusive Economic Zone (EEZ). This habitat map was incorporated into SCP of a proposed expanded MPA network that includes offshore protected areas and meets National objectives. The proposed network will increase protection of the pelagic realm (>30 m depth) of the EEZ from 0.002% to 6.0%. We contend that bioregional analyses based on publicly available remote-sensing data are useful for identification of offshore habitats, especially when robust biological data are unavailable, as a framework for ecosystem reporting, and for inclusion in a systematic design for a representative offshore MPA network. Further research should focus on modelling and mapping the permanence of pelagic habitats and different spatio-temporal scales of variability, validating habitat boundaries with biological data, and understanding the threats and efficacy of achieving pelagic protection through management mechanisms like MPAs. [ABSTRACT FROM AUTHOR]

Abiotic determinants of community composition on shallow reefs are seldom examined at a scale transcending biogeographic regions, and knowledge for the western Indian Ocean is sparse. To address this deficit, turnover in reef community composition was quantified, using gradient forest analyses, along gradients of nine abiotic variables collected in situ or via remote sensing at 54 sites across and within three bioregions: Tropical Western Indian Ocean (Tropical WIO), Delagoa and Natal, spanning 4800 km of east African coastline (5.2-31.1°S). All oceanographic variables differed significantly among bioregions. At a scale across bioregions, wave height declined northwards, while temperature increased. Values for suspended inorganic sediments, chlorophyll- a concentration [chl- a], turbidity and nutrients were all lowest in Delagoa, in association with the scarcity of rivers there. The most novel and unexpected finding was that the northwards decline in wave action was more strongly associated with changes in community composition across bioregions than any other variable. Temperature was the second-most important variable at that scale. Within bioregions, temperature and [chl- a] had strongest relationships with community composition in the Tropical WIO. By contrast, in Delagoa, reef profile, susceptibility to sand inundation and reef heterogeneity were most strongly associated with community composition; and in Natal, depth, turbidity and suspended sediment were foremost. Variables of greatest importance within bioregions distilled to (1) those influencing food/energy supply ([chl- a], turbidity, depth and suspended sediments), which were of particular importance in the Tropical WIO and Natal bioregions, and (2) those altering sand inundation and small-scale current dynamics of reefs (profile, heterogeneity and depth), which were leading factors in the Delagoa Bioregion. [ABSTRACT FROM AUTHOR]

Aim The species-area relationship-based method of setting habitat-specific conservation targets assumes that detectability of species is perfect. However, this assumption is often violated. This paper aimed to combine species-area relationship ( SAR)-based target setting with multispecies occupancy models to better represent communities with a large proportion of rare species, such as marine invertebrate macrofauna, include variable species detection and quantify uncertainty around conservation targets. Location South African West Coast continental shelf. Methods The macro-infaunal dataset used in these analyses consisted of 427 species from 42 sites and 220 samples. To examine the effect of variable species detection and include uncertainty around conservation targets, we compared asymptotic estimator-based targets with those based on multispecies site occupancy models ( MSOMs) in a Bayesian framework, which allowed us to account for the observation process and quantify uncertainty more comprehensively. Results Targets based on MSOM were generally higher than those based on asymptotic estimators, with wider credible intervals. Between 10% and 15% (95% credible interval) of the area should be protected to represent 80% of the species, with the exception of one habitat with many common species that had a conservation target of 2%. Main conclusions Detection error-corrected targets based on MSOM are higher than uncorrected targets based on asymptotic estimators for habitats with lower detection and higher proportions of rare species. Our estimated conservation targets are close to the 10% target for marine habitats set by the Convention of Biological Diversity and in line with international studies but should be considered minimum targets as they do not take into account species persistence. Our results affirm the value of the modified SAR approach, which is applicable to any marine or terrestrial ecosystem. Unlike earlier methods, our modification naturally quantifies uncertainty in estimated conservation targets providing a measure of target robustness for decision-makers. [ABSTRACT FROM AUTHOR]

Marine unconsolidated sediment habitats, the largest benthic ecosystem, are considered physically controlled ecosystems driven by a number of local physical processes. Depth and sediment type are recognised key drivers of these ecosystems. Seascape (i.e., marine landscape) habitat classifications are based solely on consistent geophysical features and provide an opportunity to define unconsolidated sediment habitats based on processes which may vary in distribution through space and time. This paper aimed to classify unconsolidated sediment seascapes and explore their diversity in an eastern boundary upwelling region at the macro-scale, using the South African west coast as a case study. Physical variables such as sediment grain size, depth and upwelling-related variables (i.e., maximum chlorophyll concentration, austral summer bottom oxygen concentration and sediment organic carbon content) were included in the analyses. These variables were directly measured through sampling, or collated from existing databases and the literature. These data were analysed using multivariate Cluster, Principal Components Ordination and SIMPER analyses (in PRIMER 6 + with PERMANOVA add-in package). There were four main findings; (i) eight seascapes were identified for the South African west coast based on depth, slope, sediment grain size and upwelling-related variables, (ii) three depth zones were distinguished (inner, middle and outer shelf), (iii) seascape diversity in the inner and middle shelves was greater than the outer shelf, and (iv) upwelling-related variables were responsible for the habitat diversity in both inner and middle shelves. This research demonstrates that the inclusion of productivity and its related variables, such as hypoxia and sedimentary organic carbon, in seascape classifications will enhance the ability to distinguish seascapes on continental shelves, where productivity is most variable. [ABSTRACT FROM AUTHOR]

• Condition is still seldom or poorly defined in marine ecological studies. • A critical review of methods and indicators for condition assessments is provided. • Five Indicator categories, which vary in terms of data requirements and inference. • This review supports indicator selection & framework development for assessments. This review provides a broad conceptual overview of different approaches to measuring marine ecosystem condition and guidance for framework development (particularly relevant for developing countries). The objectives were to review definitions of ecosystem condition and identify the core approaches and key challenges within the research area. Furthermore, we reviewed the advantages and disadvantages of different indicators that can be used for condition assessments. A semi-systematic approach drawing from more than 300 studies covering a broad range of methods was followed. Generally, definitions of ecosystem condition are based on known changes to the ecosystem, but ultimately, they should align with the definition of an ecosystem and consider ecosystem structure and functioning. As far as possible, the definition should relate an observed state to a reference condition or ecological target. Importantly, definitions of condition should be practical, scalable and always provided when conducting condition assessments. Five indicator categories were identified including pressures, physical parameters, biological structure, functional structure and ecological models. Indicators mostly focus on drivers of change (i.e. ex situ pressures) or the structure of the ecosystem, as these data are easier to obtain. While valuable, these classes of indicators can only provide an indirect appraisal of ecosystem functioning in instances where the relationship between pressure, structure and functioning are known. Indicators that measure structure and functioning of an ecosystem can be used to directly report on condition; however, the data (and monitoring) requirements make them impractical in most instances. Ideally, integrated assessments, that measure indicators from all indicator categories, should be prioritised to provide a comprehensive overview of condition. However, this often requires transdisciplinary collaboration, substantial research capacity (and associated funding) and time to collect the necessary data. An alternative is to select a few strategic indicators that can provide data to address the definition of ecosystem condition and at the same time provide a feasible approach to address the project specific research objectives. Where possible, a data-derived approach should be followed as in situ measurements have potential to improve the understanding of impacts of anthropogenic pressures on ecosystem functioning, and in turn facilitate better management of human activities and enhance ecosystem functioning. [ABSTRACT FROM AUTHOR]