DOI: 10.5061/dryad.3j9kd51vd
title: Data from: Differences in subtidal macrobenthic community structures and influencing factors between Jindo and Jeju Islands in South Korea

description: Although islands in South Korea have been significantly impacted by human
 activities, marine ecological studies focusing on island coasts have been
 limited. Due to their distinct characteristics, Macrobenthos are
 extensively utilized to assess the impact of anthropogenic influences on
 the marine environment. In August 2010, August 2011, and September 2012,
 samples of macrobenthic communities, bottom water, and sediment were
 collected from the subtidal zones around southern Jindo and northern Jeju
 Islands. Macrobenthos were identified to the species level using a
 stereomicroscope. Bottom seawater quality was evaluated, with a focus on
 dissolved heavy metal concentrations (As, Cr, Cd, Cu, Pb, and Zn).
 Additionally, we measured the organic matter content and mean grain size
 of the sediment. There were marked differences in macrobenthic community
 structures between the two islands, including the number of species,
 species abundance, species richness index, and Pielou’s evenness index
 (p&lt;0.05). Cluster analysis and Non-metric analysis revealed
 variations in macrobenthic communities between the two islands and over
 the years 2010, 2011, and 2012. According to the Biota-Environment
 Matching (BIO-ENV), distance-based redundancy analysis (dbRDA), and
 Distance-based Linear Model analyses, the principal environmental
 variables influencing the distribution of macrobenthic communities are Cd
 and As. These variations likely result from different levels of human
 activity on each island. Moreover, interannual variations in macrobenthic
 communities, especially in 2012, were predominantly influenced by Pb and
 Cr, likely due to alterations in the influence of the Changjiang diluted
 water.
description: Sampling Collection and Processing Sample
 collection occurred in August 2010, August 2011, and September 2012,
 establishing fourteen sampling sites in Jindo (S1-S7) and Jeju Islands
 (S8-S14) for each collection period. At each site, sediment and
 macrobenthic samples were gathered using a 0.1 m² Van Veen grab; the
 former covering an area of 0.1 m² and the latter 0.2 m². Additionally,
 bottom water samples were collected using a Rosette sampler, and
 parameters such as temperature, salinity, pH, and dissolved oxygen (DO)
 were measured using a YSI 6920 multiparameter sonde (YSI Inc., Yellow
 Springs, OH, USA). Each site's macrobenthic samples were sieved
 through a 0.5 mm mesh and preserved in 10% neutral formalin solution,
 while sediment samples were stored in a deep freezer for subsequent
 analysis. A 2 L sample of bottom water was stored directly in the freezer,
 and an additional 2 L sample was filtered using glass-fiber filter papers.
 Both the filtered water and the filter paper were kept in the deep freezer
 for future analysis.  In the laboratory, macrobenthic
 samples were identified to the species level and quantified using a
 dissecting microscope (SMZ-168, Motic Ltd., China). Dissolved heavy metals
 (As, Cr, Cd, Cu, Pb, and Zn) in the bottom water were measured by placing
 400 ml of seawater into a 500 mL Teflon separatory funnel, adjusting the
 pH to approximately 4.5 using an ammonium acetate buffer. A 1 mL mixture
 of organic chelating agents (APDC/DDDC) was then added and agitated for 10
 seconds. Subsequently, 10 mL of chloroform was incorporated and stirred at
 300 rpm for 5 minutes. After resting for 10 minutes, the organic solvent
 layer was separated and collected in a Teflon beaker. The solvent was
 evaporated by heating at 80°C until dry, and the residue was decomposed
 with concentrated nitric acid. Finally, 1-2 mL of diluted nitric acid was
 added, and the heavy metal content was analyzed using Inductively Coupled
 Plasma Mass Spectrometry (Agilent 7700, Agilent Inc, USA). Suspended
 solids were quantified by filtering and drying 200 mL of bottom seawater
 with glass fiber filter paper. Total Nitrogen (TN) and Total Phosphorus
 (TP) levels in bottom seawater were determined using colorimetric and
 spectrophotometric methods with an automated analyzer (QuAAtro SFA, Seal
 Analytical Ltd., UK). A 50 g sediment sample was dried at 80°C for 48
 hours and subsequently heated in a muffle furnace at 550°C for 4 hours to
 measure ignition loss (IL). The concentrations of acid volatile sulfide
 (AVS) and chemical oxygen demand (COD) in the sediment were measured using
 COD titration and AVS detection tube methods. The wet sieving method was
 applied to analyze the mean grain size of the sediment. All analyses of
 seawater and sediment samples complied with the Notification of Marine
 Environmental Process Test Standards (National Institute of Fisheries
 Science, 2010), and each test was performed in triplicate to ensure
 accuracy.
description: # Differences in subtidal macrobenthic community structures and
 influencing factors between Jindo and Jeju Islands in South Korea
 [https://doi.org/10.5061/dryad.3j9kd51vd](https://doi.org/10.5061/dryad.3j9kd51vd) ## Description of the data and file structure Sample collection occurred in August 2010, August 2011, and September 2012, establishing fourteen sampling sites in Jindo (S1-S7) and Jeju Islands (S8-S14) for each collection period (Figure 1). At each site, sediment and macrobenthic samples were gathered using a 0.1 m² Van Veen grab; the former covering an area of 0.1 m² and the latter 0.2 m². Additionally, bottom water samples were collected using a Rosette sampler, and parameters such as temperature, salinity, pH, and dissolved oxygen (DO) were measured using a YSI 6920 multiparameter sonde (YSI Inc., Yellow Springs, OH, USA). Each site's macrobenthic samples were sieved through a 0.5 mm mesh and preserved in 10% neutral formalin solution, while sediment samples were stored in a deep freezer for subsequent analysis. A 2 L sample of bottom water was stored directly in the freezer, and an additional 2 L sample was filtered using glass-fiber filter papers. Both the filtered water and the filter paper were kept in the deep freezer for future analysis. ### Files and variables #### File: Abundance.xlsx **Description:** The file 'Abundance.xlsx' contains the macrobenthic abundance data from fourteen sampling sites in in Jindo (S1-S7) and Jeju Islands (S8-S14). ##### Variables * The abbreviation "s" stands for site. #### File: latitude\_and\_longitude.xlsx **Description:** The file Latitude_and_longitude.xlsx contains the specific coordinates of fourteen sampling sites in in Jindo (S1-S7) and Jeju Islands (S8-S14). ##### Variables * The abbreviation "s" stands for site. #### File: Environment\_factors\_.xlsx **Description:** The file 'Environmental_factors.xlsx' contains the environmental variable data for each site  from fourteen sampling sites in in Jindo (S1-S7) and Jeju Islands (S8-S14). ##### Variables * The abbreviations "Wt," "DO," "SS,"TN,''TP," "Mean," "IL," "COD,"and "AVS" represent water temperature(°C) , dissolved oxygen (mg/L), suspended solids  (mg/L), total Nitrogen (mg/L), total phosphorusand (mg/L),  mean grain size (∮), ignition loss (%), chemical oxygen demand (mg/kg), and acid-volatile sulfide respectively (mg/kg). The unit for heavy metal concentrations in seawater is ㎍/L.