DOI: 10.5061/dryad.bnzs7h4qw
title: Half a century of echinoid population decline in the northern Gulf of Aqaba, Red Sea

description: 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 attributed to the
 accelerated regional urbanization, rather than the direct effect of a
 single environmental variable, is suggested as a key facilitating driver
 of the observed declines. This study reveals ongoing, alarming declines of
 key echinoid species, calling for rapid, species-aware management. We
 highlight the necessity to transition from year-long to decades-long
 monitoring to facilitate the detection of ongoing, long-term trends.
description: # 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 ##### Variables * site: site name * date: date of
 survey (MM/DD/YYYY) * month: month of survey * year: year of survey *
 time: day/night * transect/knoll no: number of sampling  * m2: square
 meter * depth (m): depth of the survey in meters * Diadema setosum :
 number of indivduals * no_m2: number of individuals per square meter *
 n/a: not available (data was not recorded) #### File: Raw_Data_Eilat.csv
 **Description:** Sea urchin abundance data from six sites at the northern
 end of the GOA. ##### Variables * site: site name * date: date of
 survey (DD/MM/YYYY) * month : month of survey * year: year of survey *
 time: day/night * transect/knoll no: number of sampling  * m2: square
 meter * depth (m): depth of the survey in meters * Diadema setosum :
 number of indivduals * Echinometra EZ: number of indivduals * Tripneustes
 gratilla : number of indivduals * Heterocentrotus mammilatus : number of
 indivduals * Echinothrix calamaris : number of indivduals * Asthenosoma
 marisrubri: number of indivduals * Eucidaris metularia: number of
 indivduals * Prionocidaris baculosa: number of indivduals ## Code/software
 n/a