Fig. 4.

(A and B) Changes in ${\mathrm{O}}_2$ (A) and ${\mathrm{\Omega }}_{Ar}$ (B) caused by anthropogenically enhanced nutrient inputs (ANTH minus CTRL simulations) in the Santa Monica Bay, along the cross-shore section marked with a black line in Fig. 2A averaged during spring–summer between years 1997 and 2000. (C and D) Time series of one full year from February 1997 to February 1998 of ${\mathrm{O}}_2$ (C) and ${\mathrm{\Omega }}_{Ar}$ (D) at 50-m depth averaged over the Los Angeles coast. The solid black line shows the CTRL simulation and the colored lines the ANTH simulation. The difference between ANTH and CTRL is highlighted in yellow. (E and F) Average relative ${\mathrm{O}}_2$ change (100 × [ANTH − CTRL]/CTRL) (E) and average absolute ${\mathrm{\Omega }}_{Ar}$ change (ANTH − CTRL) (F) at 50-m depth in the Los Angeles coast. Eutrophication increases ${\mathrm{O}}_2$ and ${\mathrm{\Omega }}_{Ar}$ at the surface, due to enhanced photosynthesis, and decreases them below the surface, due to enhanced respiration.