Water quality is defined by its effect on sea life

We just completed another group of stories in the ongoing series we’re calling “Taking the Pulse of Puget Sound.” This latest story package is about marine water quality and marine sediments. (The stories themselves require a subscription.)

Noctiluca, a type of plankton that could disrupt the food web, has grown more prevalent in recent years. Photo by Christopher Krembs, Eyes Over Puget Sound
Noctiluca, a type of plankton that could disrupt the food web, has grown more prevalent in recent years.
Photo by Christopher Krembs, Eyes Over Puget Sound

For all my years of environmental reporting, I have to say that I’ve never really understood the meaning of water quality. Keeping the water free of chemicals and fecal bacteria is one thing. Safe levels of oxygen, temperature, acidity and suspended sediment are other important factors.

But in the real world, you never find ideal conditions. You take what you get: physical conditions dictated by weather, climate and bathymetry; a strange brew of toxic chemicals; and a mix of nutrients and organic material, all drifting through complex cycles of life and death.

Water quality means nothing without the context of living things. More than 1,000 species of tiny organisms live in or on the mud at the bottom of Puget Sound. In many areas, sensitive species have disappeared. We are left with those that can tolerate harsher conditions. Why are they dying off? What can be done about it?

Some plankton species are becoming more dominant, and the effects on the food web are unknown. When water quality is poor, Jellyfish are displacing forage fish, disrupting the food supply for larger fish.

We know that toxic chemicals are spilling into Puget Sound in stormwater and getting into the food web, first touching the tiniest organisms and eventually causing havoc for fish, marine mammals and humans. Compounds that mimic hormones are affecting growth, reproduction and survival for a myriad of species. Because of biomagnification, some chemicals are having serious effects at concentrations that could not be measured until recently.

Puget Sound can’t cleanse itself by flushing its chemicals and waste out to sea, as most bays do. Puget Sound is long and narrow and deep, and the exchange of water takes a long time. Most of the bad stuff floating in the water just sloshes back and forth with the daily tides.

We can’t forget that some of the good stuff floating around are microscopic plants that feed the food web, along with a variety of larvae that will grow into fish, shellfish and many other creatures. But many of these planktonic life forms are vulnerable to chemicals, which can reduce their ability to survive against predators, tipping the balance in unknown ways.

Understanding water quality is not so much about measuring what is in the water as understanding the effects on living things. Which species are missing from a given area of Puget Sound, and what killed them off?

Biological monitoring has been around for a long time, but we may be entering a new phase of exploration in which we begin to connect the dots between what takes place on the land, how chemicals and nutrients get into the water, and what that means for every creature struggling to survive.

We have some brilliant people working on this problem in the Puget Sound region. I would like to thank everyone who has helped me gain a better understanding of these issues, as I attempt to explain these complexities in my stories.

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While I was looking into the sediment story, Maggie Dutch of Ecology’s sediment monitoring team introduced me to a huge number of benthic invertebrates. In a blog she calls “Eyes Under Puget Sound,” she talks about the monitoring program and offers a slideshow of some of the bottom creatures. See also Ecology’s Flickr page.

For some amazing shots of polychaete worms, check out the work of marine biologist and photographer Alex Semenov who took these colorful pix in Russia and Australia.

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