Sea-floor communities of the scoop-type Lov Inlet (the White Sea, the Kandalaksha Bay) were investigated. The comparison with similar data from the beginning of 1970th was carried out. It was found that under the pycnocline the Arctic type fauna with dominating species Portlandia arctica still remains. Above the pycnocline, essential changes have been found in comparison with 40 years old data. Bivalve mollusks had been dominating in 1970-s, while now the Polychaeta species Alitta virens holds a leading position. Also, strong changes were observed within community of the head-inlet threshold. In 1970-s a dense settlement of brown algae Saccharina latissima had been recorded on the most of the area. In 2010-s, only single thalli of this species were encountered. The water-column structure was analyzed in details. Integrated vertical profiles of temperature, salinity and oxygen content were investigated. It was found out, that the oxycline was situated almost at the same depth with the pycnocline . The oxygen content increased with the depth. Such situation is possible only when deep-water exchange occurs during winter time. This allows to propose that in winter time cold water enriched by oxygen drains from the surface into scoops near-bottom water-layers. From our observations, it was suggested that the summer stratification of the Lov Inlet waters is a result of winter advective processes. The time of complete water exchange in the inlet was estimated on the base of data on the fresh-water drain and compensative reverse flow, using the model and taking into account mixing processes. This time is equal to approximately 200 years. It allowed to assess the risk managementof the inlet. As a result, we recommend to prohibit any activity which may restrict water-exchange and provoke organic pollution.