The Daily Bucket is a regular feature of the Backyard Science group. It is a place to note any observations you have made of the world around you. Rain, sun, wind...insects, birds, flowers...meteorites, rocks...seasonal changes...all are worthy additions to the bucket. Please let us know what is going on around you in a comment. Include, as close as is comfortable for you, where you are located. Each note is a record that we can refer to in the future as we try to understand the patterns that are quietly unwinding around us.
Salish Sea
Pacific Northwest
Old spent seaweed floating by the shore yesterday inspires this green bucket. The bright spring sunshine brought out its glowing chlorophyl, even though these shreds are past their expiration date.
(All photos by me. In Lightbox...click to enlarge)
Seaweed and munchers below the tangle of red algae filaments...
Sea Lettuce (Ulva spp.) is a marine green-algae, simple in structure, only 2 cell layers thick, making it translucently bright emerald green. Like other algae, it has no need for the roots, stems, leaves or flowers of land plants because its watery environment provides all its needs. The sea supports it, nutrients can be absorbed by each cell directly from the water, and its offspring can float away in the current. The ocean is big sky country, so plenty of light is available too. Life is good for Sea Lettuce, and if it wasn't for just a few limiting factors it could easily take over!
One problem is surging water currents which can tear these delicate blades from their holdfasts. Unanchored to some solid surface, it gets thrashed by swirling tidal currents, washed up onto the dry shore to dessicate, or carried out to sea where it starves to death in the nutrient-poor open ocean. Most aquatic productivity is in shallow nearshore waters where nutrients are plentiful, both stirred up from bottom detritus and in runoff from land. In fact an overabundance of Sea Lettuce is an indicator of excessive nutrient runoff, usually from livestock waste, fertilizers or leaking septic systems. One of my local bays here is such a spot. That big green zone visible at a super low tide is all Sea Lettuce.
These shreds now drifting in shallow water above the sand and shells will shortly be washed up on the beach, where they will dry out and die. But this is an ongoing process. Sea Lettuce blades don't grow longer than one season, and get torn away by the rough water of winter storms. Come spring, fresh blades will grow from the old holdfasts, and baby Ulva "swarmers" swim off to find any hard surface to attach to, beginning their new lives. These empty shells, and rocks, and driftwood and pilings and boat hulls, and anything else, will soon be covered with an emerald green fuzz of young Sea Lettuces.
Besides getting dried out, torn up, or washed away, Sea Lettuce can meet its end one other way. Many herbivorous animals find it a great source of food, packed with protein, minerals and vitamins. Among the many grazers of Sea Lettuce are some local dabbling ducks.
These Gadwalls have been munching steadily on Sea Lettuce for several months in this bay. Usually they swim away from shore when I stop my bike to look at them, but on this occasion the tide was low and they were far down the beach from me.
Pintails are more interested in the invertebrates stuck to Sea Lettuce and living amongst the mats along the bottom. But they'll consume the seaweed too. When the mud is a bit farther than they can lean over to reach, they "tip", as they are doing in the second pic.
My favorite Sea Lettuce munchers are the Wigeons. By the Anacortes ferry dock is a small bay that is the mother-lode of Sea Lettuce. It piles up in drifts and berms. A huge flock of Wigeons winters in this bay. Here are a few wading in their food.
People waiting for the ferry wander up and down the beach, so the Wigeons are constantly paddling to and from the shore. They particularly keep their distance from woozles. There's a mad dash for open water.
Dying Sea Lettuce turns pale, like this. Its nutritional quality declines and it falls to pieces.
All the munchers are looking for fresh stretchy bright green sheets. Sea Lettuce is edible and nutritious for people too.
Others benefits? Makes a great fertilizer for veggie gardens, as the indigenous Scots and Irish have known for centuries. With no vascular tissue, it breaks down quickly, releasing 60-some trace minerals, and amino acids. I've had good results with various kinds of seaweed, whatever happens to wash up in large quantity. Living Sea Lettuce can also be used to deliberately "soak up" nutrient pollution and then composted.
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Your turn now. What are you observing in nature as we move into spring?
And -
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