Seasonal highlights


Sea hare ©Julie Hatcher

Spring is springing

We all love to see the Spring “springing” and, whilst we welcome the return of some of our most well-known creatures on land spare a thought for some of the unseen Spring spectacles happening in our seas.

At this time of year a number of creatures are breeding, ready to release eggs and larvae in time for the plentiful food that will be available during the Spring plankton blooms. Plankton, derived from the Greek word “planktos” meaning wanderer, are drifting organisms often only visible with a microscope. Some types – the phytoplankton - photosynthesise and so the increase in availability of light as the days get longer and warmer causes a bloom. As a result we see an increase in larval and animal plankton – the zooplankton, which eat the phytoplankton. This is the basis of most food chains in the marine environment and so this increase in food availability during Spring and early Summer means that we also start to welcome the arrival of migratory species such as basking sharks, mackerel and several species of seabirds into the Irish Sea.

On the sea floor, dead men’s fingers, a type of soft coral, will be shedding the outer “skin” along with anything that may have settled on them during the Winter months. The tentacles are then ready to extend to feed again. Annual seaweeds will have started appearing whilst those perennial in nature will start their Spring time growth.

You may start noticing translucent gelatinous balls known as sea gooseberries with their two trailing tentacles, stranded on the beach or in rockpools. Look carefully and you may see the iridescent ripple of the “combs”. Next to arrive, towards the end of Spring, will be ghostly blooms of jellyfish - several species can be seen in Welsh waters.

Closer to shore keep an eye out in the rockpools for some of our most weird and wonderful creatures – the sea slugs. Sea hares, so called after their tentacles that resemble a pair of hare ears, can be spotted as they come to shallower waters to breed and lay their long pink egg strings at this time of year. The largest and most common is the sea lemon with its rosette egg ribbon that can be easily seen on the lower shore. Sea slugs, unlike their land-based counterparts, are indeed some of the prettiest creatures in the sea. Take a magnifier and a little pot when the tides are at their lowest and you may see the beautiful smaller sea slugs with their alien looks. You’ll need to put them in water to see them in their full glory.

Although mostly an unseen phenomenon, springtime in the sea is a hive of activity and excitement and you can get a taster of this by going for a good old rockpooling session. Choose low water, preferably on a spring tide when the moon is full or new, to get to the most interesting areas or just wander on the beach to see what you can find.

How inappropriate to call this planet Earth when it is clearly Ocean
Arthur C. Clarke