Diversity and ecological role of true crabs (crustacea, brachyura) in the St Lucia Estuary, iSimangaliso Wetland Park, in response to global change

This work has explored novel concepts of crab vulnerability, recovery and resilience under unprecedented climatic changes in South Africa’s first UNESCO World Heritage Site. By showing how large salinity shifts and prolonged interruption of the marine connection can drastically affect brachyuran diversity and community structure in St. Lucia Lake, the potential cascading effects on ecosystem functioning were estimated. Only 15 crab species were recorded within the system during this study, compared to the 26 species that were known to occur prior to the recent environmental shift (i.e. 58% decline). The impact of this biodiversity collapse has negatively affected the associated mangrove ecosystem in particular, with the entire community of fiddler crabs persisting only in a small area near the estuary mouth. Gut fluorescence measurements have shown that, due to a lack of tidal Influence, their grazing impact on microphytobenthic biomass may become unsustainable. However, although adults are able to survive in this environment, the larvae require a marine connection; and they are thus unable to tolerate the wide fluctuations in salinity currently prevailing in the system. The study concludes that brachyurans are key factors to consider during conservation planning, as they are crucial to maintaining ecosystem function in the face of environmental change. This research is of global relevance, as many similar estuarine and coastal lakes around the world are currently experiencing similar state shifts. All six chapters included in the thesis have already been published in the peer-reviewed literature; and the project results have also earned Nasreen the NRF award of Next-Generation Researcher of the Year for 2015

Community and marine conservation in South Africa: Are we still missing the mark?

Marine Protected Areas (MPAs) in South Africa have a long history with currently 5% of the mainland’s ocean territory protected. The MPAs are celebrated and appreciated for their representative coverage of several habitat types and their ecological benefits. However, the story of correlational coastal community exclusion is not one that is often told in the ‘success’ story of South African MPAs. In this review we describe the history of marine conservation in South Africa and examine how the legislation and motivation has evolved since Apartheid

Description of a new montane freshwater crab (Arthropoda, Malacostraca, Decapoda, Potamonautidae) from the Eastern Cape, South Africa

SUPPLEMENTARY INFORMATION: Authors: Gavin Gouws Data type: phylogenetic Explanation note: TABLE S1: Representatives of valid southern African Potamonautes species included in the phylogenetic analysis used to contextualise divergences and confirm the affinities of specimens included in the current study. Four species of Maritomonautes were included as outgroup taxa. GenBank accession numbers for the 16S rRNA and cytochrome c oxidase subunit I (COI) included and the data sources are provided; TABLE S2: Uncorrected sequence divergences, expressed as percentages, as calculated from a 549 nucleotide alignment of 16S rRNA mtDNA sequences (below diagonal) and a 660 nucleotide alignment of the protein-coding mtDNA cytochrome c oxidase subunit I (COI) fragment (above diagonal), between representative of Potamonautes included in the present study. Newly-sampled specimens are identified as Potamonautes danielsi and P. amathole sp. nov. This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.A new species of freshwater crab, Potamonautes amathole sp. nov., is described from the WinterbergAmathole mountain range in the Eastern Cape Province, South Africa. Morphologically, P. amathole Peer & Gouws, sp. nov. most closely resembles P. tuerkayi but can be distinguished by key morphological characters including the variation in the shape of the subterminal segment of gonopod 2 between both species. Genetically, P. amathole Peer & Gouws, sp. nov. is placed within the clade of small-bodied, mountaindwelling crabs including P. parvispina, P. parvicorpus, P. brincki, P. tuerkayi, P. baziya, and P. depressus. The new species is found in slow-moving mountain streams and pools at high altitudes. The continued discovery and description of new freshwater crab species reinforces the need for ongoing research, especially in under-sampled regions.https://zookeys.pensoft.netPlant Production and Soil Scienc

Description of a new montane freshwater crab (Arthropoda, Malacostraca, Decapoda, Potamonautidae) from the Eastern Cape, South Africa

A new species of freshwater crab, Potamonautes amathole sp. nov., is described from the Winterberg-Amathole mountain range in the Eastern Cape Province, South Africa. Morphologically, P. amathole Peer & Gouws, sp. nov. most closely resembles P. tuerkayi but can be distinguished by key morphological characters including the variation in the shape of the subterminal segment of gonopod 2 between both species. Genetically, P. amathole Peer & Gouws, sp. nov. is placed within the clade of small-bodied, mountain-dwelling crabs including P. parvispina, P. parvicorpus, P. brincki, P. tuerkayi, P. baziya, and P. depressus. The new species is found in slow-moving mountain streams and pools at high altitudes. The continued discovery and description of new freshwater crab species reinforces the need for ongoing research, especially in under-sampled regions

Tufa stromatolite ecosystems on the South African south coast

Following the first description of living marine stromatolites along the South African east coast, new investigations along the south coast have revealed the occurrence of extensive fields of actively calcifying stromatolites. These stromatolites have been recorded at regular distances along a 200-km stretch of coastline, from Cape Recife in the east to the Storms River mouth in the west, with the highest density found between Schoenmakerskop and the Maitland River mouth. All active stromatolites are associated with freshwater seepage streams flowing from the dune cordon, which form rimstone dams and other accretions capable of retaining water in the supratidal platform. Resulting pools can reach a maximum depth of about 1 m and constitute a unique ecosystem in which freshwater and marine organisms alternate their dominance in response to vertical mixing and the balance between freshwater versus marine inflow. Although the factors controlling stromatolite growth are yet to be determined, nitrogen appears to be supplied mainly via the dune seeps. The epibenthic algal community within stromatolite pools is generally co-dominated by cyanobacteria and chlorophytes, with minimal diatom contribution

A socio-ecological survey in Inhambane Bay mangrove ecosystems : biodiversity, livelihoods, and conservation

Mangroves are highly productive ecosystems that provide a variety of ecosystem services to local communities. Mangrove ecosystems are important blue carbon ecosystems that support unique fauna, flora, and livelihoods. The decline and degradation of mangrove populations, mostly due to anthropogenic impacts and climate change, necessitate protection worldwide. There is limited research on the conservation and management of these ecosystems in Mozambique. A combination of six biodiversity surveys, thirty-one semi-structured interviews and participant observation at six sites was used to describe and understand mangrove ecosystems in Inhambane Bay. This study is among the first to involve local community leaders as academic co-authors, thus highlighting the value of local ecological knowledge and community involvement, both of which are necessary for a comprehensive understanding of mangrove ecosystems. Social and ecological approaches were integrated to describe mangrove ecosystems, perceived ecosystem services and benefits to local communities. This study has identified areas of increased mangrove cover and areas with disturbance. Out of the seven mangrove species that occur in Inhambane Bay, Avicennia marina was the most abundant mangrove species in at least three sites, and Xylocarpus granatum the least abundant mangrove species, present only in two sites. Perceived benefits include provisioning, supporting and regulating services. Community initiatives to protect mangroves include enforcing environmental laws, prohibiting cutting mangrove trees, and replanting. This study shows that community initiatives for law enforcement and mangrove restoration play an important role in raising awareness and actively protecting mangroves

Prospects and challenges of environmental DNA (eDNA) metabarcoding in mangrove restoration in Southeast Asia

Species detection using environmental DNA (eDNA) is a biomonitoring tool that can be widely applied to mangrove restoration and management. Compared to traditional surveys that are taxa-specific and time-consuming, eDNA metabarcoding offers a rapid, non-invasive and cost-efficient method for monitoring mangrove biodiversity and characterising the spatio-temporal distribution of multiple taxa simultaneously. General guidelines for eDNA metabarcoding are well-established for aquatic systems, but habitat-specific guidelines are still lacking. Mangrove habitats, as priority ecosystems for restoration in Southeast Asia, present unique prospects and challenges in these regards. Environmental DNA metabarcoding can be used to (1) track functional recovery in ecological restoration, (2) prioritise conservation areas, (3) provide early warning for threats, (4) monitor threatened taxa, (5) monitor response to climate change, and (6) support community-based restoration. However, these potential applications have yet been realized in Southeast Asia due to (1) technical challenges, (2) lack of standardised methods, (3) spatio-temporal difficulties in defining community, (4) data limitations, and (5) lack of funding, infrastructure and technical capacity. Successful implementation of eDNA metabarcoding in mangrove restoration activities would encourage the development of data-driven coastal management and equitable conservation programs. Eventually, this would promote Southeast Asia’s shared regional interests in food security, coastal defence and biodiversity conservation

Modern supratidal microbialites fed by groundwater: functional drivers, value and trajectories

Microbial mats were the dominant habitat type in shallow marine environments between the Palaeoarchean and Phanerozoic. Many of these (termed ‘microbialites’) calcified as they grew but such lithified mats are rare along modern coasts for reasons such as unsuitable water chemistry, destructive metazoan influences and competition with other reef-builders such as corals or macroalgae. Nonetheless, extant microbialites occur in unique coastal ecosystems such as the Exuma Cays, Bahamas or Lake Clifton and Hamelin Pool, Australia, where limitations such as calcium carbonate availability or destructive bioturbation are diminished. Along the coast of South Africa, extensive distributions of living microbialites (including layered stromatolites) have been discovered and described since the early 2000s. Unlike the Bahamian and Australian ecosystems, the South African microbialites form exclusively in the supratidal coastal zone at the convergence of emergent groundwater seepage. Similar systems were documented subsequently in southwestern Australia, Northern Ireland and the Scottish Hebrides, as recently as 2018, revealing that supratidal microbialites have a global distribution. This review uses the best-studied formations to contextualise formative drivers and processes of these supratidal ecosystems and highlight their geological, ecological and societal relevance

MtDNA lineage diversity of a potamonautid freshwater crab in KwaZulu-Natal, South Africa

Five species of freshwater crab (genus Potamonautes) are known from KwaZulu-Natal, South Africa, whilst a sixth (Potamonautes isimangaliso) was recently described from the iSimangaliso Wetland Park. Earlier molecular studies of crab diversity in the province were largely limited in geographic scope or employed genetic markers, ill-suited for identifying intraspecific diversity. Possible species-level diversity or cryptic taxa may have thus remained undetected. In this study, lineage diversity was examined in a widespread species, Potamonautes sidneyi, using mitochondrial sequence data, to determine whether this species harbours cryptic diversity that could be of conservation importance in the province, particularly with respect to the iSimangaliso Wetland Park. The taxonomic status of P. isimangaliso was also assessed. Mitochondrial sequence data were generated and analysed to identify unique lineages and to examine their distributions. Phylogenetic analyses were used to determine whether these lineages represented known or potentially novel species, using comparative data from southern African Potamonautes species. Seven independent networks were identified within P. sidneyi and substantial structure was observed amongst sampling localities. Phylogenetic analyses revealed two distinct, divergent lineages in P. sidneyi. One was positively assigned to P. sidneyi, whereas the placement of the other suggested a novel species. These results suggested possible species diversity within P. sidneyi, with one lineage occurring in the north-east of the province, around the iSimangaliso Wetland Park. Potamonautes isimangaliso was clearly allied to Potamonautes lividus, but genetic divergences suggested that P. isimangaliso is a distinct taxon and that P. lividus may represent a species complex. Conservation implications: This study confirmed unique freshwater crab diversity, both within KwaZulu-Natal and associated with the iSimangaliso Wetland Park