Figure 4: Similarity and temperature.
From: Rapid biotic homogenization of marine fish assemblages
(a) Mean oceanographic surface temperature (depth<10 m) data in the first quarter of the year for the study area, in relation to year. The plot shows an increase in mean temperature through time (OLS regression, r2=0.22, n=162). (b) Relationship between temperature and latitude ignoring year, indicating that, on average, water temperature is cooler in more northern localities. (c) Box plot (median, quartiles, range and outliers) of pairwise temperature differences between latitudinal bands (analogous to the plot in Figure 2). Years in which the mean pairwise difference is below the overall mean are shown in red, and those above the mean in blue. There is a significant negative correlation (Spearman rs=−0.46, P=0.026, n=23) between mean annual temperature difference (this plot) and mean annual Jaccard dissimilarity (1-Jaccard). This indicates that the reduction in temperature difference parallels the reduction in differences in community composition. (d) Median slope of the relationship between temperature and latitude in each year of the study showing the steepness of the temperature gradient is declining over time. This trend is significant (Spearman rs=0.6, P=0.001, n=27).
