Half a century of echinoid population decline in the northern Gulf of Aqaba, Red Sea

In the face of global coral decline, coral reefs in the Gulf of Aqaba, northern Red Sea are considered a coral reef refuge from global warming and acidification, with echinoid herbivory playing a fundamental role in maintaining their balance. Like many echinoderms, echinoids are known for their ‘boom-and-bust’ population fluctuations. However, as population fluctuations are influenced by multiple, complex, and non-linear processes that operate at various temporal scales, short-term studies may fail to capture the true trajectories of population trends. We explored echinoid population dynamics in the Gulf of Aqaba, spanning 15 years (2007 to 2022), complemented by historical data dating back to the 90’s and 70’s. We show that while some species oscillated around a steady mean, others collapsed by up to 98%. Consequently, the once most common herbivores on these reefs currently account for only a fraction of their population size from half a century ago. Increased anthropogenic stress att..., , # Half a century of echinoid population decline in the northern Gulf of Aqaba, Red Sea

Dataset DOI: [10.5061/dryad.bnzs7h4qw](https://doi.org/10.5061/dryad.bnzs7h4qw)

## Description of the data and file structure

The dataset contains sea urchin abundance surveyed at the northern Gulf of Aqaba (GOA) from 2007 to 2022. The data files contain species-level abundance on six surveyed sites—North Beach (NB), Kisoski, Dekel, Eilat Coral Nature Reserve (ECNR), the Interuniversity Institute (IUI), and Princess Beach. Due to the diverse structural complexity of the study sites, three surveying methods were utilized: (I) belt-transects, (II) coral assemblages (knolls) surveys, and (III) quadrats. Detailed information on the specific surveying method and effort applied at each site and time can be found in the Supporting Information, Table S1 of the published paper.

### Files and variables

#### File: Dekel_site_all_years.xlsx

**Description:** Diadema setosum abundance from the Dekel site

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