It is a logical hypothesis that ocean food-chains could capture and store carbon that would lower CO2 levels in surface waves, so that those waves would absorb more CO2 from the atmosphere and transmit it downward to replenish whatever is migrating around in deeper waters.
But would increased rates of CO2 absorption by the oceans compensate for all the capacity missing on land due to all the land-based forests and other ecosystems that have been removed and replaced with human developments?
The problem is that whenever trees and other organisms are removed from land, the energy balance of that land between sunlight and waste-heat shifts toward more heat and less life-energy (i.e. all the cellular activity and growth that is powered by solar energy filtering through ecosystems).
Basically, developed areas function more like deserts than forests in terms of absorbing sunlight and re-emitting it as convection. The convection currents cause wind and evaporation to be stronger than they otherwise would be, and that leads to more H2O-vapor in the atmosphere to blanket heat along with other greenhouse gases, such as CO2.
So from a broader/longer-term perspective, increased oceanic absorption of CO2 wouldn't compensate for the failure of land development activities to preserve trees and ecology at levels of density equal to that which occurs on natural land that hasn't been developed.
So while the oceans may provide some assistance in the struggle to bring down CO2 levels, they shouldn't deter us from the task of re-integrating trees and other carbon-absorbing life-forms into areas developed by humans at levels of density comparable to natural forests.