The phrase "accompanied by a gradual decrease in" is correct and usable in written English.
It can be used when describing a situation where one phenomenon occurs alongside a slow reduction in another variable or factor.
Example: "The experiment showed that the increase in temperature was accompanied by a gradual decrease in pressure."
Alternatives: "coupled with a slow decline in" or "alongside a gradual reduction in".
The normal physiological decline of testosterone in men is due to a decrease in the number of androgen-secreting Leydig cells and is accompanied by a gradual decrease in spermatogenesis, although men often remain fertile for many more years.
Increased plamacytosis in the bone marrow is accompanied by a gradual decrease in fat cells and hematopoietic marrow with an increase in interstitial water.
With increasing B content, more [0 0 2]-oriented grains were formed, accompanied by a gradual decrease in grain size of the nanocrystallites.
The excess of the implanted deuterium dose 1.8 × 1017 D/cm2 is accompanied by a gradual decrease in the b peak maximum temperature, which becomes equal to 430 K at a dose of 6.4 × 1017 D/cm2.
Mosquito aging is accompanied by a gradual decrease in the physiological capacity to adapt to environmental stresses.
These intrusions were accompanied by a gradual decrease in eye jerk saccade size.
This gradual change in transformation character is accompanied by a gradual decrease of the interface velocity.
The collagen content in the granulation tissue increases up to the third week, from the moment when the wound appeared, which is accompanied by a gradual decrease of the fibroblast amount up to the moment when they disappear in the process of apoptosis [ 73].
Under natural conditions, weaning involves the gradual decrease in milk supply from the mother, and a concomitant increase in the intake of solid food by the young, which is accompanied by a gradual reduction in maternal-filial bond [ 54].
This gradual dampening of chromatin fiber movement observed upon differentiation is accompanied by a gradual reduction in the spatial amplitude of the detected vibration, from 87 nm to 32 nm (as depicted in Figure 4M).
In the following years, Yilmaz et al. [ 26] demonstrated that a decline in eGFR was accompanied by a gradual reduction in sTWEAK in CKD patients.
