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Baseline assessment of Benthic Invertebrate Communities in the Southern Benguela: insights from Table Mountain National Park MPA, Robben Island MPA, and the seas of Good Hope EBSA
Author(s)
Snyders, Laurenne
Date Issued
2024
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
Areas afforded protection in the ocean space, for example, Marine Protected Areas (MPAs),
assist in managing the marine environment by promoting fisheries sustainability, ensuring
that marine ecosystems function effectively, and serve to protect the range of species living
there. For these areas, baseline information is key in order to determine the range of
organisms inhabiting these spaces. The aim of this thesis was to gain a better understanding
of the benthic macro-invertebrate fauna of the southern Benguela ecoregion in South Africa,
with a focus on the Table Mountain National Park Marine Protected Area (TMNP MPA),
Robben Island Marine Protected Area (RI MPA) and the Seas of Good Hope Ecologically or
Biologically Significant Area (EBSA). A comprehensive benthic survey was conducted from
August to September 2019 to provide baseline information of the macro-benthic invertebrate
fauna, including their diversity, assemblage patterns and the environmental variables that
influence them. This study focussed on the visual assessments using two different camera
systems: a simple Drop camera and a towed camera (Ski-Monkey).
A total of 48 stations were sampled and imagery software was used to analyse representative
images per station. The habitat characteristics and species abundance of both hard and soft
bottom substrata were recorded. Diversity indices selected for analyses and interpretation of
data included species richness (S), abundance (N), Pielou’s evenness index (J’), which
measures diversity along with species richness and the Shannon-Weiner diversity index (H'),
measuring the diversity of species in a community.
The species accumulation curves for the study area did not reach an asymptote, indicating
that further sampling could reveal additional species and enhance the overall understanding
of the area's biodiversity. Despite the latter, we have used the best available data from the
survey to provide a better understanding and provide baseline information for the sampling
areas. These data, while not exhaustive, offers valuable insights into macro-benthic
invertebrate communities and serves as an important foundation for future research and
conservation efforts in the southern Benguela ecoregion.
The drop camera sampled a higher mean percentage cover of benthos and rock, and a lower
percentage of sand compared to the ski-monkey. The significantly higher percentage cover of
sand in the Ski-Monkey samples is expected since a towed camera system is better suited for
use on soft sediment. The mean species diversity from images collected by the drop camera (i.e. richness, abundance, percentage cover, evenness), compared to that collected by the Ski Monkey were found to be significantly different (P < 0.05) with the Ski-Monkey being the
higher of the two. Large variations in diversity were found between the samples. Community
structure was analysed and differences in community structure were found to be related to
depth and substrate type.
Findings from this study has provided an important overview of the region's biodiversity,
revealing a diverse range of species, shedding insight on diversity and community structure and
providing a strong foundation on which to build future research efforts. Significant differences
were found in species richness, diversity, and abundance between camera systems. When
comparing sampling effort between the two camera systems, images collected by the Ski-Monkey
captured a higher species richness, diversity and abundance compared to the Drop camera
system. The study showed that the southern Benguela ecosystem is heterogeneous and the
distribution of organisms varied spatially according to substrate type, location and depth. These
results are important for MPA conservation and management, as well as for understanding
benthic invertebrate diversity and abundance in the region. The study provides valuable baseline
information for future research and highlights the need for continuous monitoring of the protected
areas in the southern Benguela ecoregion. The high concentration of endemism and restricted
species in the South-Western Cape is further highlighted by the lack of alien species in the
research area, emphasizing the significance of protecting these ecosystems against invasive
species. Baseline data on the benthic invertebrate fauna, related habitats, and environmental
factors affecting their distribution and abundance in the southern Benguela ecoregion have been
supplied by this thesis. The two environmental factors that have been found to best explain the
observed community patterns are substrate type and depth. The adoption of long-term monitoring
systems and the application of standardized efforts to guarantee the efficacy of conservation
initiatives are among the recommendations for future research. Overall, this study makes a
substantial contribution to our knowledge of the benthic ecosystems in the southern Benguela
ecoregion and offers insightful data for the preservation and management of the marine
biodiversity in the area. The findings of this research will also help shape decisions on marine
spatial planning, which will support South Africa's efforts to preserve and manage its marine
environments sustainably.
assist in managing the marine environment by promoting fisheries sustainability, ensuring
that marine ecosystems function effectively, and serve to protect the range of species living
there. For these areas, baseline information is key in order to determine the range of
organisms inhabiting these spaces. The aim of this thesis was to gain a better understanding
of the benthic macro-invertebrate fauna of the southern Benguela ecoregion in South Africa,
with a focus on the Table Mountain National Park Marine Protected Area (TMNP MPA),
Robben Island Marine Protected Area (RI MPA) and the Seas of Good Hope Ecologically or
Biologically Significant Area (EBSA). A comprehensive benthic survey was conducted from
August to September 2019 to provide baseline information of the macro-benthic invertebrate
fauna, including their diversity, assemblage patterns and the environmental variables that
influence them. This study focussed on the visual assessments using two different camera
systems: a simple Drop camera and a towed camera (Ski-Monkey).
A total of 48 stations were sampled and imagery software was used to analyse representative
images per station. The habitat characteristics and species abundance of both hard and soft
bottom substrata were recorded. Diversity indices selected for analyses and interpretation of
data included species richness (S), abundance (N), Pielou’s evenness index (J’), which
measures diversity along with species richness and the Shannon-Weiner diversity index (H'),
measuring the diversity of species in a community.
The species accumulation curves for the study area did not reach an asymptote, indicating
that further sampling could reveal additional species and enhance the overall understanding
of the area's biodiversity. Despite the latter, we have used the best available data from the
survey to provide a better understanding and provide baseline information for the sampling
areas. These data, while not exhaustive, offers valuable insights into macro-benthic
invertebrate communities and serves as an important foundation for future research and
conservation efforts in the southern Benguela ecoregion.
The drop camera sampled a higher mean percentage cover of benthos and rock, and a lower
percentage of sand compared to the ski-monkey. The significantly higher percentage cover of
sand in the Ski-Monkey samples is expected since a towed camera system is better suited for
use on soft sediment. The mean species diversity from images collected by the drop camera (i.e. richness, abundance, percentage cover, evenness), compared to that collected by the Ski Monkey were found to be significantly different (P < 0.05) with the Ski-Monkey being the
higher of the two. Large variations in diversity were found between the samples. Community
structure was analysed and differences in community structure were found to be related to
depth and substrate type.
Findings from this study has provided an important overview of the region's biodiversity,
revealing a diverse range of species, shedding insight on diversity and community structure and
providing a strong foundation on which to build future research efforts. Significant differences
were found in species richness, diversity, and abundance between camera systems. When
comparing sampling effort between the two camera systems, images collected by the Ski-Monkey
captured a higher species richness, diversity and abundance compared to the Drop camera
system. The study showed that the southern Benguela ecosystem is heterogeneous and the
distribution of organisms varied spatially according to substrate type, location and depth. These
results are important for MPA conservation and management, as well as for understanding
benthic invertebrate diversity and abundance in the region. The study provides valuable baseline
information for future research and highlights the need for continuous monitoring of the protected
areas in the southern Benguela ecoregion. The high concentration of endemism and restricted
species in the South-Western Cape is further highlighted by the lack of alien species in the
research area, emphasizing the significance of protecting these ecosystems against invasive
species. Baseline data on the benthic invertebrate fauna, related habitats, and environmental
factors affecting their distribution and abundance in the southern Benguela ecoregion have been
supplied by this thesis. The two environmental factors that have been found to best explain the
observed community patterns are substrate type and depth. The adoption of long-term monitoring
systems and the application of standardized efforts to guarantee the efficacy of conservation
initiatives are among the recommendations for future research. Overall, this study makes a
substantial contribution to our knowledge of the benthic ecosystems in the southern Benguela
ecoregion and offers insightful data for the preservation and management of the marine
biodiversity in the area. The findings of this research will also help shape decisions on marine
spatial planning, which will support South Africa's efforts to preserve and manage its marine
environments sustainably.
Additional information
Thesis (Master of Conservation Science)--Cape Peninsula University of Technology, 2024
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