After the Facts – Ayum Creek Monitoring

The estuary portion of the Ayum Creek site is carpeted with Sea Asparagus (Salicornia). This edible but very salty plant is both spongy and crunchy, a very interesting underfoot sensation! We also observed a native parasite, Salt Marsh Dodder (Cuscuta salina) which occupies seasonal alkaline or saline habitats. Salt Marsh Dodder wraps itself around wetland vegetation and taps them for nutrients. In appearance it resembles silly string, although we were also able to observe it in flower.

We found numerous examples of tree “twinning” wherein two trees, sometimes of different species grow together and merge at points. The phenomena is called inosculation and occurs as a natural grafting process. It occurs when trees grow very closely together; the bark becomes chafed away when the trees rub together in the wind and the trees may self-graft at that point. Read more.

Stumbling upon the fragile fragment of a robin egg shell prompted the question, why are robin eggs blue? Torrey found two sources which speak to this pigmentation. The first article points to the colour blue as providing a safe balance between light and dark which prevents excess heat absorption through the shell and also blocks excess transmission of light which could damage the embryo. The second article suggests that the hue of the shell can indicate the health of the mother and chicks; the brighter the blue, the better the health.

At the time of our monitoring hike, the Ayum estuary had nearly dried out in some places due to a minus tide and we were able to take a close look at the Purple Martin (Progne subis arboricola) nesting boxes which have been erected to promote population stabilization. Purple Martins in BC experienced a dramatic decline, reaching a low 5 pairs or perhaps fewer in 1985. The presumed reason for population decline is competition with invasive species like the European starling. Development pressures also impacted nesting areas. Read more.

While crossing the creek we spotted a bright red dragonfly, Cardinal Meadowhawk (Sympetrum), and it seemed to like the attention! Nearly ten times (as our photographer inched closer!) the dragonfly left its perch, flew in a large circle, and returned to the same branch. Eventually we caught its good side.

The estuary is graced by many beautiful Arbutus trees (Arbutus menziesii) or Pacific Madrone tree. We discussed some features including an interaction with fungi that creates a burned appearance on branches. Often, two or more types of fungus work in tandem, damaging and killing the trees (Read more). Openings in the bark such as vandalism or other cuts are sites of vulnerability and infection for arbutus. We also discussed fungal leaf blight and climate change. Read more here.

Investigating the creek we found Caddisfly larvae which resemble twigs with very tiny black legs. Caddisfly, mayfly, and stonefly, all have important roles as bio-indicators for the health of streams. Read more.

Drifting in large green mats on the creek surface was Ulva intestinalis, a green algae commonly known as ‘gutweed’ because of its flattened, tubular shape. This algae indicates freshwater influence in a seawater environment. Read more.

Ayum is full of invasive Scotch Broom. Walking through the brush in the hot sun we could hear the seed pods bursting with the sound of rice krispies! Seeds remain viable up to 80 years, and dispersal is triggered by heat. Scotch Broom is thriving in these hotter and drier summers.

Monitoring excursions provide an excellent forum for discussions. Volunteers and staff alike walk away with some new understanding. We are very grateful to Jim Roberts, a biologist and underwater photography whiz who has joined us several times to share knowledge about the creek system and salmon run.