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Tropical seagrass beds and coral reefs are among the most productive and diverse ecosystems on Earth and provide ecosystem services, such as fish production and coastal protection, and support livelihoods of millions of people. At the same time, these ecosystems are threatened globally by anthropogenic disturbances, such as overfishing, pollution and global warming. Implementation of marine protected areas (MPAs) is one of the main strategy to achieve conservation goals and has proven to restore biodiversity and fish stocks, at least on coral reefs. However, studies assessing protection effects on seagrass communities are scarce. Moreover, many MPAs are government-managed and increasingly criticized for excluding and marginalizing local communities. Therefore, MPAs that are managed by the communities themselves, i.e. community-managed MPAs, constitute a promising yet poorly studied alternative. The aim of this thesis was to investigate ecological effects of government- and community-managed MPAs on seagrasses, corals, and their associated benthic and fish communities in the tropical seascape. We used a space-for-time replacement approach and surveyed coral and seagrass communities in fished areas, recently established community MPAs (1-6 years of protection) and old government MPAs (20-44 years) in coastal Kenya, East Africa. Results suggest that only a few years of protection in community MPAs can increase diversity of benthic communities (Paper I), and also protect economically valuable fish stocks (Paper II). Protection also appeared to induce a community shift, from dominance of pioneering and stress-tolerant coral and seagrass species in fished areas, to structurally complex climax species in old government MPAs (Paper I). Additionally, effects of protection on seagrass communities seems to be most apparent in the mid-lagoon by favoring seagrass species with high shoot density; an effect that was mostly caused by species turnover but also phenotypic plasticity., At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.

Tropical seagrass beds and coral reefs are among the most productive and diverse ecosystems on Earth and provide ecosystem services, such as fish production and coastal protection, and support livelihoods of millions of people. At the same time, these ecosystems are threatened globally by anthropogenic disturbances, such as overfishing, pollution and global warming. Implementation of marine protected areas (MPAs) is one of the main strategy to achieve conservation goals and has proven to restore biodiversity and fish stocks, at least on coral reefs. However, studies assessing protection effects on seagrass communities are scarce. Moreover, many MPAs are government-managed and increasingly criticized for excluding and marginalizing local communities. Therefore, MPAs that are managed by the communities themselves, i.e. community-managed MPAs, constitute a promising yet poorly studied alternative. The aim of this thesis was to investigate ecological effects of government- and community-managed MPAs on seagrasses, corals, and their associated benthic and fish communities in the tropical seascape. We used a space-for-time replacement approach and surveyed coral and seagrass communities in fished areas, recently established community MPAs (1-6 years of protection) and old government MPAs (20-44 years) in coastal Kenya, East Africa. Results suggest that only a few years of protection in community MPAs can increase diversity of benthic communities (Paper I), and also protect economically valuable fish stocks (Paper II). Protection also appeared to induce a community shift, from dominance of pioneering and stress-tolerant coral and seagrass species in fished areas, to structurally complex climax species in old government MPAs (Paper I). Additionally, effects of protection on seagrass communities seems to be most apparent in the mid-lagoon by favoring seagrass species with high shoot density; an effect that was mostly caused by species turnover but also phenotypic plasticity., At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.

Tropical seagrass beds and coral reefs are among the most productive and diverse ecosystems on Earth and provide ecosystem services, such as fish production and coastal protection, and support livelihoods of millions of people. At the same time, these ecosystems are threatened globally by anthropogenic disturbances, such as overfishing, pollution and global warming. Implementation of marine protected areas (MPAs) is one of the main strategy to achieve conservation goals and has proven to restore biodiversity and fish stocks, at least on coral reefs. However, studies assessing protection effects on seagrass communities are scarce. Moreover, many MPAs are government-managed and increasingly criticized for excluding and marginalizing local communities. Therefore, MPAs that are managed by the communities themselves, i.e. community-managed MPAs, constitute a promising yet poorly studied alternative. The aim of this thesis was to investigate ecological effects of government- and community-managed MPAs on seagrasses, corals, and their associated benthic and fish communities in the tropical seascape. We used a space-for-time replacement approach and surveyed coral and seagrass communities in fished areas, recently established community MPAs (1-6 years of protection) and old government MPAs (20-44 years) in coastal Kenya, East Africa. Results suggest that only a few years of protection in community MPAs can increase diversity of benthic communities (Paper I), and also protect economically valuable fish stocks (Paper II). Protection also appeared to induce a community shift, from dominance of pioneering and stress-tolerant coral and seagrass species in fished areas, to structurally complex climax species in old government MPAs (Paper I). Additionally, effects of protection on seagrass communities seems to be most apparent in the mid-lagoon by favoring seagrass species with high shoot density; an effect that was mostly caused by species turnover but also phenotypic plasticity., At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.

Tropical seagrass beds and coral reefs are among the most productive and diverse ecosystems on Earth and provide ecosystem services, such as fish production and coastal protection, and support livelihoods of millions of people. At the same time, these ecosystems are threatened globally by anthropogenic disturbances, such as overfishing, pollution and global warming. Implementation of marine protected areas (MPAs) is one of the main strategy to achieve conservation goals and has proven to restore biodiversity and fish stocks, at least on coral reefs. However, studies assessing protection effects on seagrass communities are scarce. Moreover, many MPAs are government-managed and increasingly criticized for excluding and marginalizing local communities. Therefore, MPAs that are managed by the communities themselves, i.e. community-managed MPAs, constitute a promising yet poorly studied alternative. The aim of this thesis was to investigate ecological effects of government- and community-managed MPAs on seagrasses, corals, and their associated benthic and fish communities in the tropical seascape. We used a space-for-time replacement approach and surveyed coral and seagrass communities in fished areas, recently established community MPAs (1-6 years of protection) and old government MPAs (20-44 years) in coastal Kenya, East Africa. Results suggest that only a few years of protection in community MPAs can increase diversity of benthic communities (Paper I), and also protect economically valuable fish stocks (Paper II). Protection also appeared to induce a community shift, from dominance of pioneering and stress-tolerant coral and seagrass species in fished areas, to structurally complex climax species in old government MPAs (Paper I). Additionally, effects of protection on seagrass communities seems to be most apparent in the mid-lagoon by favoring seagrass species with high shoot density; an effect that was mostly caused by species turnover but also phenotypic plasticity., At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.

Tropical seagrass beds and coral reefs are among the most productive and diverse ecosystems on Earth and provide ecosystem services, such as fish production and coastal protection, and support livelihoods of millions of people. At the same time, these ecosystems are threatened globally by anthropogenic disturbances, such as overfishing, pollution and global warming. Implementation of marine protected areas (MPAs) is one of the main strategy to achieve conservation goals and has proven to restore biodiversity and fish stocks, at least on coral reefs. However, studies assessing protection effects on seagrass communities are scarce. Moreover, many MPAs are government-managed and increasingly criticized for excluding and marginalizing local communities. Therefore, MPAs that are managed by the communities themselves, i.e. community-managed MPAs, constitute a promising yet poorly studied alternative. The aim of this thesis was to investigate ecological effects of government- and community-managed MPAs on seagrasses, corals, and their associated benthic and fish communities in the tropical seascape. We used a space-for-time replacement approach and surveyed coral and seagrass communities in fished areas, recently established community MPAs (1-6 years of protection) and old government MPAs (20-44 years) in coastal Kenya, East Africa. Results suggest that only a few years of protection in community MPAs can increase diversity of benthic communities (Paper I), and also protect economically valuable fish stocks (Paper II). Protection also appeared to induce a community shift, from dominance of pioneering and stress-tolerant coral and seagrass species in fished areas, to structurally complex climax species in old government MPAs (Paper I). Additionally, effects of protection on seagrass communities seems to be most apparent in the mid-lagoon by favoring seagrass species with high shoot density; an effect that was mostly caused by species turnover but also phenotypic plasticity., At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.

Tropical seagrass beds and coral reefs are among the most productive and diverse ecosystems on Earth and provide ecosystem services, such as fish production and coastal protection, and support livelihoods of millions of people. At the same time, these ecosystems are threatened globally by anthropogenic disturbances, such as overfishing, pollution and global warming. Implementation of marine protected areas (MPAs) is one of the main strategy to achieve conservation goals and has proven to restore biodiversity and fish stocks, at least on coral reefs. However, studies assessing protection effects on seagrass communities are scarce. Moreover, many MPAs are government-managed and increasingly criticized for excluding and marginalizing local communities. Therefore, MPAs that are managed by the communities themselves, i.e. community-managed MPAs, constitute a promising yet poorly studied alternative. The aim of this thesis was to investigate ecological effects of government- and community-managed MPAs on seagrasses, corals, and their associated benthic and fish communities in the tropical seascape. We used a space-for-time replacement approach and surveyed coral and seagrass communities in fished areas, recently established community MPAs (1-6 years of protection) and old government MPAs (20-44 years) in coastal Kenya, East Africa. Results suggest that only a few years of protection in community MPAs can increase diversity of benthic communities (Paper I), and also protect economically valuable fish stocks (Paper II). Protection also appeared to induce a community shift, from dominance of pioneering and stress-tolerant coral and seagrass species in fished areas, to structurally complex climax species in old government MPAs (Paper I). Additionally, effects of protection on seagrass communities seems to be most apparent in the mid-lagoon by favoring seagrass species with high shoot density; an effect that was mostly caused by species turnover but also phenotypic plasticity., At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.

Marine ecosystems are under increasing human pressure and therefore in need of effective management. Marine protected areas (MPAs) can reduce the effects of local disturbances on habitat-forming benthic organisms like corals and seagrasses and are well-known to affect species composition. However, we know considerably less about their effects on organisms’ traits (physiological, morphological, and/or behavioural characteristics), which in turn dictate how organisms respond to stressors and influence ecosystem processes and services. We conducted a field survey along the Kenyan coast to assess the effects of MPAs on species and trait composition of seagrass assemblages; an important group of habitat-forming plants in shallow coastal areas that form the basis for multiple ecosystem services. We measured five morphological traits (shoot density, leaf length and width, number of leaves per shoot, and above:below-ground biomass ratio) on multispecies seagrass assemblages within government MPAs, community MPAs, and fished areas in three habitat zones (shallow, mid-lagoon and, reef). Using causal modelling (path analysis) of multivariate data, we found that MPAs influence seagrass species composition and, indirectly, trait composition in mid-lagoon areas. Meanwhile, there were no MPA effects in the shallow intertidal (potentially because of impacts from MPA-related tourism), and weak effects in the reef zone, presumably due to competition from corals. Finally, most of the MPA effects on overall seagrass trait composition were explained by species turnover, rather than phenotypic plasticity. In conclusion, MPAs appear to be an effective conservation tool for seagrass assemblages by reducing local disturbances and favouring seagrass species with certain traits, primarily in mid-lagoon areas. However, the lack of MPA effect in intertidal areas highlights the need for management approaches that regulate human impacts across the whole tropical coastal zone.