burrow into it to various depths and thus utilize the nutrient resources 

 of the various layers of the bed. 



Under subarctic conditions, and to some extent under the conditions 

 of the high boreal subzone, extensive, heavily silted spaces in the 

 estuarine intertidal zone are quite sparsely populated, with macrophytes 

 frequently absent, while the sparse macrofauna are represented primarily 

 by the amphipods and Mesidotea enotomon . 



The biomass of the mussels and oyster banks (almost exclusively 

 animal) reaches several kilograms per iir. A significant biomass (up to 

 a few kilograms per m^) is also found in stands of marine grasses, 

 mostly plant biomass. In the remaining communities, the biomass is 

 significantly lower and reaches a few tens or hundreds of grams per m^, 

 both in the tropics and in the temperate zone. 



160 



