Milford’s Changing Tide Pools

As a child I would often visit my grandparents who owned a small cottage facing Anchor Beach in the Woodmont borough of Milford.

I would explore the tide pools in this rocky coastal habitat zone.

Under almost any rock, my brothers and I would find eels. Blue mussels (Mytilus edulis) seemed to be everywhere. So were common periwinkles (Littorina littorea), which we called snails. If we walked the sand bars at low tide, we would be wary of having our toes pinched by calico crabs (ovalipes ocellatus)—sometimes called lady crabs—with their colorful spotted, somewhat purplish carapace, or top shell. Green crabs (Carcinus maenas) abounded as well but were less feisty than the colorful calicos. Blue crabs (Callinectes sapidus) would appear in August.

Nature, like shifting sands, is dynamic; always changing. Depending on your perspective, these changes can be thought of as positive (cardinals expanding their range northward, for example) or negative (English sparrows and starlings coming to the western hemisphere and impacting our native bluebirds).

Today our once plentiful blue mussels have disappeared from our rocky coastal areas. The ribbed mussels (Modiolus demissus), associated more with emerging salt marsh areas amongst the rocky tide pools, seem to be increasing. Eels are seldom found under those rocks; however, Asian shore crabs are here by the millions under those same rocks. At first blush that would seem to be a negative, but with Asian shore crabs we have seen increased numbers of the shorter-necked marine goose called Brant. I suspect the crustacean-eating blackfish are being seen in greater numbers as well.

Species like the common periwinkles may need to be renamed uncommon periwinkles and those colorful toe-nipping calico crabs gone as well... at least in the Woodmont area.

Hermits crabs of several varieties (Pagurus longicarpus i.e. long clawed and Pagurus pollicarus, i.e. flat clawed) continue to be present. As you might know, hermits outgrow one shell and quickly seek to hide out in a larger one…often a subtidal nassa or whelk. Other mollusks such as the moon snail (two species, Polinices duplicatus and Lunatia heros) inhabit those sand bars, as do the oyster drills (Urosalpinx cinerea) which can often be found under tide pool rocks covered with various species of seaweed (rockweeds with bladders i.e. Fucus vesiculosus).

Oystercatchers, a large black and white shorebird with a bright red-orange bill seem to be increasing along our coast. I wonder if they have developed a taste for the exotic Asian shore crabs. I hope so, because the shore crabs are prolific. I once found myself swimming amongst millions of the tiny larval creatures. The oystercatchers are quite beautiful and make a wonderful call when distressed or simply want to alert their buddies that it is time to move to the nearest tide pool.

So, as the tides ebb and flow, so do the species which inhabit the intertidal zone. Have fun!

—Tim Chaucer