Regional and Environmental Data
For comparison to the field dataset, a regional dataset was created
using identifications from OBIS. All bivalve records for Australia were
downloaded on 4th May 2020 using the R package robis (Provoost and
Bosch, 2020). Data were spatially restricted to only include coastal
cells within the latitudinal range of the field sites (16.7 – 37.2 °S).
Species names were checked against the World Register of Marine Species
using the package worms in R (Holstein, 2018, WoRMS Editorial Board,
2018) in order to remove erroneous species names and synonyms and to
check family assignments. Only records with georeferenced collection
locality data recorded to 2 decimal places, valid species names, and
collection dates after 1980 were included. This resulted in a regional
dataset including 7,480 records of 600 species.
For bivalves in our study area, 612 records are recorded on OBIS as
“Human Observation”. To avoid potentially erroneous identifications,
only records tagged as “Preserved Specimen” were retained for our main
analysis. We ran an additional analysis with the observational data
included to make comparisons.
Records were pooled into 0.1° cells to approximate the spatial scale of
the field data. Cells with fewer than 10 records were omitted to allow
for more accurate diversity estimation. To account for the difference in
the number of cells between datasets, a subset of the OBIS data was
created that only included cells centred on field sites.
Environmental data for the eastern coastline were downloaded from the
CSIRO Atlas of Living Seas (Ridgway et al. , 2002), which provides
ocean water properties on a 0.5° grid, on 10th May 2020. Variables
downloaded were the most recently available ones for mean annual sea
surface temperature, mean annual salinity, mean annual dissolved oxygen
content, and mean annual nitrate, silicate, and phosphate content.