Correlation between Coral Reef Condition and the Diversity and Abundance of Fishes and Sea Urchins on an East African Coral Reef

Oceans, Journal Year: 2022, Volume and Issue: 3(1), P. 1 - 14

Published: Jan. 4, 2022

Coral reefs are one of the most diverse marine ecosystems, providing numerous ecosystem services. This present study investigated relationship between coral reef condition and diversity abundance fishes, on a heavily fished East African at Gazi Bay, Kenya. Underwater visual censuses were conducted thirty 50 × 5 m belt transects to assess fishes. In parallel, 25-m length each same was recorded with photo-quadrats community structure benthic characteristics. For statistical analyses, multi-model inference based Akaike Information Criterion used evaluate support for potential predictor variables fish diversity. We found that genus richness negatively correlated macroalgae, whereas cover positively both herbivorous invertebrates (sea urchins) family richness. Similarly, appeared mainly invertebrate abundance, although no correlates could be identified. very low, but it appears that, contrary some locations coast, sea urchin not high enough having negative influence assemblages. Due increasing threats reefs, is important understand among components overfished such as Bay.

Language: Английский

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Detection of sea urchins (Diadema setosum) colony distribution on UAV imagery data using fuzzy logic spproach

Kuwait Journal of Science, Journal Year: 2025, Volume and Issue: unknown, P. 100389 - 100389

Published: Feb. 1, 2025

Language: Английский

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Pioneer generation shapes long-term recovery of coral populations

Published: May 12, 2025

Reef recovery following a disturbance largely depends on successful coral recruitment and the absence of chronic stressors. However, recent events show increasing homogenization, with dominant species replacing high diversity that once characterized these ecosystems. In this study, we analysed nine-year dataset (2012–2020) describing reef towards Pocillopora-dominated state in Taiwan devastating typhoon. Tracking eight cohorts, assessed growth, survival reproduction. Pocillopora peaked during first three years, but mortality surged fourth year. The initial generation had highest rates, while by fifth year, newly settled individuals failed to survive beyond two years. By 2020, 83% consisted corals from 2012–2016, 38% originating alone (2012). This pioneer was primary contributor growth reproduction, emphasizing reef's reliance early settlers, leading an ageing community. While generations were critical recovery, their dominance may have driven gradual loss biodiversity. Our findings highlight importance development underscores risk only few after recovery.

Language: Английский

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Grazing effects of sea urchin Diadema savignyi on algal abundance and coral recruitment processes

Scientific Reports, Journal Year: 2020, Volume and Issue: 10(1)

Published: Nov. 23, 2020

Herbivores control algae and promote coral dominance along reefs. However, the majority of previous studies have focused on herbivorous fish. Here we investigated grazing effects sea urchin Diadema savignyi algal abundance recruitment processes. We conducted an in situ cage experiment with three density conditions D. (0, 8, 16 indiv. m-2) for months during main season Taiwan. Results demonstrated a strong by savignyi. At end experiment, average cover was 95% 0 m-2, compared to 47% 8 m-2 16% m-2. Average biomass at declined one third almost zero On other hand, negative effect observed Notably, recruits mortality small fragments (proxy juveniles) increased. Our results confirm findings indicate need balance both positive (strong control) (physical damage) influences facilitate process.

Language: Английский

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Sea Urchins Play an Increasingly Important Role for Coral Resilience Across Reefs in Taiwan

Frontiers in Marine Science, Journal Year: 2020, Volume and Issue: 7

Published: Dec. 15, 2020

Herbivores are an important functional group that control algae, create new space, and promote recruitment for coral recovery. However, on many reefs, overfishing has greatly decreased the density of herbivores, especially fishes gastropods, impairing resilience. On such overfished remnant herbivores not target species local fisheries, e.g., sea urchins, expected to play increasingly role, yet few studies, except those in Caribbean Kenya have examined non-fish relation Here, we conducted field surveys at 30 sites along three reefs Taiwan between 2016 2017, examine relative importance six key factors resilience: herbivore abundance (fishes, urchins), cover, macroalgal habitat complexity, water depth, wave exposure. The juvenile was used as a proxy Diadematid urchins ( Echinothrix spp. Diadema spp.) dominated most (19 sites) multivariable regression models showed urchin best positive predictor density. results elucidated increasing role diadematid Taiwan. Given is widespread issue, this phenomenon may be occurring globally. More studies needed remnant, but often ignored, herbivory Reef managers should consider monitoring locally incorporating them into management strategies.

Language: Английский

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Transitional Coral Ecosystem of Taiwan in the Era of Changing Climate

Coral reefs of the world, Journal Year: 2023, Volume and Issue: unknown, P. 7 - 35

Published: Jan. 1, 2023

Language: Английский

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Cost‐effective seafloor habitat mapping using a portable speedy sea scanner and deep‐learning‐based segmentation: A sea trial at Pujada Bay, Philippines

Methods in Ecology and Evolution, Journal Year: 2021, Volume and Issue: 13(2), P. 339 - 345

Published: Oct. 20, 2021

Abstract Various sampling and monitoring strategies have been developed to assess marine habitats life‐forms. However, the cost‐effectiveness of such survey methods (e.g. line intercept transects autonomous underwater vehicles) is still not high. In this paper, a practical seafloor habitat mapping method combining cost‐effective system (P‐SSS: portable speedy sea scanner) deep learning‐based quantification were proposed. P‐SSS highly transport towed‐type with five cameras arrayed on its platform. The trial was conducted at Pujada Bay, Philippines, 7 December 2019. high‐quality orthophotos high resolution ~3.0 mm/pixel successfully generated. attained efficiency 12,900 m 2 /hr. addition, in segmentation utilizing U‐Net architecture estimate coverage corals, seagrass urchins using large‐scale 2D image Overall, expected become promising tool for environmental surveys, especially areas where rich nature oceans susceptible changes, as remote islands that lack sufficient facilities.

Language: Английский

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Sea urchin harvest inside marine protected areas: an opportunity to investigate the effects of exploitation where trophic upgrading is achieved

PeerJ, Journal Year: 2022, Volume and Issue: 10, P. e12971 - e12971

Published: March 7, 2022

Background Marine protected areas (MPAs) usually have both positive effects of protection for the fisheries’ target species and indirect negative sea urchins. Moreover, often in MPAs urchin human harvest is restricted, but allowed. This study aimed at estimating effect Paracentrotus lividus within MPAs, where fish exploitation restricted its density already controlled by a higher natural predation risk. The prediction we formulated was that lowest densities commercial urchins would be found allowed compared to forbidden. Methods At this aim, collaborative database gained across five Sardinia (Western Mediterranean, Italy) outside gathered collecting abundance size data total 106 sites different degrees exploitation: no, unrestricted (NH, RH UH, respectively). Furthermore, as estimates made past monitoring efforts (since 2005) were available 75 sampled sites, each levels exploitation, rate variation also estimated. Results highlighted likely cumulative predation. overall change over time indicates only NH conditions promoted increase current local management has driven towards an important regression populations, allowing harvest. Overall, results suggest complex mechanisms, including synergistic between biotic interactions pressures, may occur on populations assessment MPA P. crucial guide decisions regulating permits. need ban avoid extreme reductions encouraged, inside are under pressures trophic upgrading.

Language: Английский

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Climate-induced species range shift and local adaptation strategies in a temperate marine protected area, Ashizuri-Uwakai National Park, Shikoku Island, western Japan

Ocean & Coastal Management, Journal Year: 2021, Volume and Issue: 210, P. 105744 - 105744

Published: June 5, 2021

Language: Английский

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Grazers and predators mediate the post-settlement bottleneck in Caribbean octocoral forests

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2022, Volume and Issue: unknown

Published: Aug. 11, 2022

Abstract Caribbean octocorals have not suffered the decades long decline in abundance that has plagued reef-building scleractinian corals. Their success and formation of octocoral forests been attributed to their continuing recruitment reef habitats. Assessing processes controlling is essential understanding predicting future. Benthic grazers on coral reefs can facilitate growth corals by reducing competitive algal turfs macroalgae or hinder through predation tissue recruits. We assessed effects grazing fishes sea urchin Diadema antillarum mesofaunal a series manipulative experiments using varying grazer/predator exclusion inclusion conditions situ ex experiments. Exposure fish significantly reduced survival single-polyp octocorals, while turf-associated mesofauna did affect neither nor survival. also found positive relationship between turf algae, potential related response deleterious effect exposure. These data suggest predators mediate mortality bottleneck characteristic recruitment. Thus, declines urchins throughout may contributed increase Caribbean, concurrent with loss scleractinians.

Language: Английский

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