Son variaciones en los ecosistemas acuáticos por efecto del cambio climático: 1)Aumento del nivel del mar e inundaciones y deslizamientos de terrenos susceptibles.
Disminución de las playas que son el hábitat de muchas especies que nidifican en ellas.
2)Aumento de las temperaturas de las aguas y cambio de la composición química de las aguas
3)Efecto sobre el fitoplancton que es un constituyente esencial en las redes tróficas marinas.

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.

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the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.