The species composition, diversity, spatial and trophic structure of macrobenthic communities of the sublitoral and lower littoral zones were studied in several lagoon ecosystems (Kandalaksha Bay, White Sea). Surveys detected 52 species of benthic invertebrates and 6 species of seaweeds and algae in the investigated ecosystems. In the sublittoral zone, the greatest species diversity, total density and biomass of species populations were found in the lagoon least closed off from the sea, located at the exit from Kislaya Inlets’ head, where marine less euryhaline species were found more. The smallest species diversity was found in the most fenced and silted lagoons of the Nikolskaya Inlet and Zelyoniy Cape, where brackish water and marine euryhaline species prevailed. An intermediate position was occupied by the lagoon of Yermolinskaya Inlet and the lagoon
near Lake Yershovskoe. In the littoral zone, as opposed to the sublittoral, common indicators of the macrobenthos community structure (total density, biomass, and less so the species diversity) increased from less regulated and open ecosystems to more enclosed ones. The exception was the lagoon of Nikolskaya Inlet, where significant overregulation and siltation led to a significant reduction in species diversity, total density and, especially, biomass of the macrobentos community. The trophic structure of macrobenthic communities of the studied lagoon ecosystems is characterized by a similar structure – the group of collector detritivores prevailed in the sublittoral zone, with an upward tendency from more open lagoons to lagoons sheltered off from the sea. In the lower littoral zone, which is more exposed to tidal impact, there was a greater amount of immobile sestonivores (Mytilus edulis), as well as scraper grazers (Littorina littorea) with the group of immobile sestonivores (M. edulis) tending to increase towards lagoons that are moderately sheltered off from the sea (the lagoon near Lake Yershovskoe lake and the lagoon of Yermolinskaya Inlet).