What affects would the plants get if their rhythm is off?
In aquatic form plants, I guess the effect won't be so drastic... In terrestrial form, this can be different, but only for annual flowering plants but not so much for perennials and evergreens. Then the effect would rather be obvious with plants below or near every light pole in the street.
For annual flowering that depends on seasonal circumstances such as light hours for growing or flowering it's much more important. When a plant is in the flowering season mode it actually reduces the vegetative growth in size such as stem length to put energy in the flowers or fruits. If it gets too much extra light when in the flowering mode it gets disturbed and confused and doesn't know any longer what to do, then it will do both make flowers and keep up growing vegetatively in size. You could compare this with a form of etiolation with less compact and smaller flower buts or fruit with longer stems in between. This you can experience with annual flowering near a street light or an automated floodlight in the garden.
Plants that do not carry flowers don't care much for it, see also, for example, your houseplants, these next to the plants in the lit streets are in the worst circumstances regarding light and circadian rhythm you can imagine because we switch the lights on and off whenever needed. Yet I need to see the first one suffering from it.
Not saying that this goes for all, I guess the ones that are sensitive to it can't be kept indoors in pots... There are more we can't keep than we can keep.
Since we have no flowering annuals in our aquariums, you could consider them houseplants... And it's trial and error, If they get light > than their LCP they will naturally utilize it and grow.
For fish, it would be a different story... I guess they are much more sensitive to it.