Why are there tons of seaweed onthe gulf coast beaches in texas this year? also barnacles? caused by what?

Question

Are these over abbundances caused somehow by weather? it covers the whole waters edge for 20-25 ft, looks brown and ugly!

Answer 1

The Midwest was flooded in late spring when farmers along the Mississippi and tributaries fertilize their fields, the run-off was full of fertilizers and nutrients useful in plant growth supplying the gulf with all the right parts of a great algae bloom.  

The algae is eaten by filter feeders and net type catching animals like barnacles to increase their population.  The brown algae is dead algae, probably from overpopulation causing a lack of dissolved carbon dioxide and sunlight.