DOI: 10.5061/dryad.69p8cz91j
title: Marine ecoregions and subecoregions within Indo-West Australian waters: A statistical approach based on species distributions

description: Aim: The Marine Ecoregions of the World (MEOW) system delineates the
 oceans into 232 ecoregions. Here, we aimed to evaluate the suitability of
 this system to represent species distributions within Indo-West Australian
 waters, explore alternative ecoregions and new subecoregions, and
 investigate environmental variables that are correlated with species
 distributions within those waters. Location: Indo-West Australia Taxa:
 Vertebrates, invertebrates, marine plants Methods: We downloaded
 occurrence data for 14,513 marine species from the Ocean Biogeographic
 Information System. We analysed differences in species composition among
 nine ecoregions within Indo-West Australian waters using pairwise
 permutational multivariate analysis of variance to evaluate how well the
 MEOW system represents species distributions within those waters. We
 delineated subecoregions within each distinct ecoregion using hierarchical
 cluster analysis with the unweighted pair-group method using arithmetic
 averages. We analysed relationships between environmental variables and
 species composition using distance-based linear models. Results: Species
 composition was significantly different among ecoregions, except for three
 adjacent regions, which were combined into a single large ecoregion.
 Hence, seven distinct ecoregions were further analysed. Our study
 identified 13 subecoregions within these ecoregions that each separate
 into ‘inshore’ and ‘offshore’ zones. Depth explained the most variation in
 species composition of the combined taxa and sea surface temperature was
 the most important parameter in explaining the variability in most taxa.
 Main conclusion: The MEOW system did not represent well the distribution
 of marine species within Indo-West Australian waters. Alternatively, we
 show that those waters encompass seven distinct ecoregions with 13
 subecoregions. The main environmental drivers of species distributions
 could be depth and sea surface temperature. The proposed ecoregions and
 subecoregions allow us to improve the biogeographic hypotheses for
 understanding the evolution of marine species and identify representative
 marine habitats and species composition for the setting of Marine
 Protected Area networks within Indo-West Australian waters.
description: Study area The study area includes nine
 currently recognised ecoregions within Indo-West Australian waters:
 Western Sumatra, Southern Java, Lesser Sunda, Bonaparte Coast, Exmouth to
 Broome, Ningaloo, Shark Bay, Houtman, and Leeuwin. A map of these
 ecoregions is available from www.marineregions.org. The study area was divided into a 1° grid-cell resolution to create 473 cells, including 83 grid cells in Western Sumatra, 70 in Southern Java, 71 in Lesser Sunda, 46 in Bonaparte Coast, 67 in Exmouth to Broome, 15 in Ningaloo, 25 in Shark Bay, 24 in Houtman, and 72 in Leeuwin. Species occurrence data Species of marine Mammalia, Reptilia, Pisces, Mollusca, Crustacea, Echinodermata, Annelida, Cnidaria, Bryozoa, Porifera, Alismatales, Chlorophyta, Rhodophyta, and Phaeophyceae were selected. Species data from Indonesian and Australian waters were downloaded from the Ocean Biogeographic Information System (OBIS) (https://obis.org) on October 20, 2019. Data were retrieved for 28,923 species and 1,497,347 location records. A total of 14,556 species from 81,968 cell records were extracted after overlaying species data and grid cells. Duplicate species within grid cells were removed. OBIS species names were matched with those in the World Register of Marine Species (http://www.marinespecies.org), and names marked as synonyms in WoRMS were linked to currently accepted names. This data evaluation reduced the number of species from 14,556 to 14,513. Grid cells that contained fewer than five species were excluded to minimise distortion in similarity analyses (Kreft & Jetz, 2010). This reduced the number of grid cells from 473 to 338. The final grid cell counts by ecoregion were 54 in Western Sumatra, 33 in Southern Java, 43 in Lesser Sunda, 42 in Bonaparte Coast, 61 in Exmouth to Broome, 9 in Ningaloo, 25 in Shark Bay, 23 in Houtman, and 48 in Leeuwin. The same approach at both finer (0.5°) and coarser (2°) resolution was conducted as a supplementary analysis. In these analyses, the number of final grid cells was 816 (49.60% of total cells) and 135 (93.75% of total cells), respectively. Environmental data Environmental variables included both surface and benthic environments: salinity, nitrate, dissolved oxygen, current velocity, temperature, pH, photosynthetically available radiation (PAR), and depth. Salinity, nitrate, dissolved oxygen, current velocity, temperature, pH, and PAR data were downloaded from Bio-ORACLE (Tyberghein et al., 2012; Assis et al., 2018), and depth data were downloaded from Global Marine Environment Datasets (IOC et al., 2003). The mean values of environmental variables within grid cells were calculated and used in the analysis.
description: The ZIP file contains three
 datasets (ecoregion data_1.Rdata, ecoregion data_05.Rdata, and ecoregion
 data_2.Rdata) and README.txt. The README file contains an explanation of
 datasets.