There is a sudden increase in the number of herbivorous fish due to the migration of some carnivorous fish from the river. what effect will this have on primary producers

Primary producers are mostly plants. Primary producers will probably experience some downfall due to the large number of fish. And if the producer species becomes extinct, then that could mean disaster for the entire community. I hope this was helpful in some way!

No because the eaeht is on a 23.5 degree axis tilt and so when it is winter the northern hemisphere is pointing away from the sun and the soutubern hemisphere is pointing toward the sun