Marine life responds to early winter warmth Gloucester Daily Times
Although the calendar, the amount of daylight, the low sun in the midday sky, and the locations of the rising and setting sun clearly tell winter's here, the air and seawater temperatures have pretty much said otherwise.
Three types of Cape Ann marine life - the lobster, common periwinkle and knotted wrack - have been affected by the unseasonably winter warmth in different ways.
The seawater temperature during the first two weeks of January ranged from 43 to 45 degrees Fahrenheit, while the air temperature frequently hit or surpassed the 50-degree mark. The ocean water even felt warm to the bare hand then. Most winters at this time see ocean temperatures below 40 degrees.
Knotted Wrack
Knotted wrack, the common, attached brown algae that resides in the midtide zone, usually goes "spawny" in the early spring. The receptacles at the tips of the plants' long fronds then swell, turn yellowish/brown and gooey and eventually release their gametes during this approximately six-week annual reproductive event.
This winter's warmth already triggered many of the knotted wracks to begin going "spawny" the first week in January. Knotted wrack's commercial value ebbs during the "spawny" period. Not only does the plant look unattractive, but it also gives off a cucumber-like odor and spoils quickly in storage.
Common Periwinkle
Common periwinkles are cold-blooded invertebrates that make their homes along the inter-tidal zone in dime- to quarter-size round shells. They move about there using muscular feet and earn a living grazing on algae and diatoms. Air and water temperatures dictate the periwinkles' levels of activity.
Mother Nature has also told the periwinkles along the rocky coast they can best survive winter's traditional cold and turbulence by bunching up in rocky crevices and on the sides of sheltered rocks at the low-tide mark. The cold usually lulls most of these animals into dormancy. Rising temperatures in the spring get them crawling to the mid- and upper-tidal zones, where they summer in tidal pools and on bare and seaweed-covered rocks.
But so far, the warm winter has not only deprived them of their regular winter break, but also kept them moving about and feeding in the midtidal zone they usually occupy in the spring and fall.
The Lobster
Early winter's exceptionally warm seawater temperatures have kept another cold-blooded creature, the lobster, coming up in the traps both inshore and midshore, flipping and flapping and grabbing at reaching hands at a time when the normally colder water would make them sluggish. These trapped lobsters have also felt warm to the bare hand. They have been so full of life lately that harvesters have even had to apply extra pressure and caution while crisscrossing their extended claws to band them or risk breaking one off.
Most lobsters summer in the shallows, winter in the depths - often in self-made holes in the mud - and spend much of the spring and fall crawling to and from these areas. Like the periwinkles, lobsters used to at least enjoy a period of dormancy during the winter and early spring. Despite this winter's warm water, the lobsters seemed to have still made those traditional movements. Some lobstermen believe they have not moved as far off as they usually do, however.
Many lobstermen believe most lobster activity, including feeding, crawling and trapping, will slow to a near standstill once the bottom water temperature drops below 38 degrees. A few lobsters always seem to trap in the cold water, and longer sets between hauls and dropping the traps practically on top of the lobsters continue to help increase the catches then. Storms also help to occasionally increase winter catches by briefly warming up the water. Sunlight can do the same in the shallow water, especially if it hits directly on the lobsters.
The bottom water temperature typically bottoms out in February and March. The water temperature was so cold last February that it chilled lobsters to the point that one could feel the cold come out of them while handling them bare-handed.
A Side Note
Regarding last week's column on the excavator and the biker, this side note should answer the last sentence in the article on why cyclist Ralph Gorvett also bikes for another challenge: "The biggest challenge is to just continue doing it," he said.
No comments:
Post a Comment