Respuesta :
The tresnd is decreasing because of the loss in kelp production due to sea urchins.
There are algae that are unicellular to multicellular in structure and they have a thalloid body that is not divided into the stem root and leaves to normal plant body having the root stem and leaves and they show and live in a wide range of habitats like in water, snow, land, marshy areas, etc and the algae have different kind of pigments like chlorophyll a, b, c, d and xanthophyll, carotenoids and according to this they are divided into green, brown, red and golden algae and the largest brown algae are called as kelps which is the largest seaweed found in the floors opf oceans and it is served as food for humans and also for sea urchins and the number of sea urchins is increasing which inturn increases the environmental pressure and they are used to eat as well the trend in the 20 to 30 years in the kelp population is that it is reducing because of sea urchins the aquatic animals because they eat kelps and clip the bottonms and due to which the sea urchins stop the keps from regrwoing as the sea urchins live there so the habitat of kelps is being lost .
To know more about algae click at https://brainly.com/question/4289110
#SPJ9
