In spring in British coastal waters these nutrient salts are rapidly used up by increasing numbers of, at first, phytoplankton and then by the zooplankton that feed on them. The importance of this process becomes clear when the reproductive patterns of coastal wildlife are looked at in more detail. There are two different strategies used by marine fish and invertebrates. Firstly, species such as barnacles, mussels, lobsters and whiting. These have larvae that hatch in spring, often in vast numbers, to take advantage of the abundant planktonic food.
Most animals belong to the first group.
They lay large numbers of eggs and rely on the large numbers of larvae hatching and simultaneously entering the plankton, so that it is quite likely that some will get enough food to grow, mature and find a suitable niche for their adult life. Opportunists The second group are more opportunistic. All these rely heavily on the chance that enough nutrients are available that there will be sufficient phytoplankton around at some point that one or two of the larvae will manage to reach maturity. The microscopic planktonic organisms, called the phytoplankton, require sunlight and minerals to grow and reproduce at a phenomenal rate. These microscopic plants are the basis of the marine food web.