Waterways are not sewers
How many of us toss things in the water, just because it is the easiest thing to do? Factually, nothing we throw into the water is helpful to our waterways, and most things are harmful. Additionally, throwing anything in the water is a violation of Virginia law.
The Code of Virginia (Section 62.1 194) specifies that “it shall be unlawful for any person to cast, throw or dump any garbage, refuse, dead animal, trash, carton, can, bottle, container, box, lumber, timber or like material, or other solid waste, except fish (bait) or crab bait in any form, into any of the waters of the Commonwealth.”
Everybody seems to throw their rockfish carcasses in the water, possibly in hopes the neighbors will notice what great fishermen they are. The excuse (which also applies to bags of lawn grass, dead squirrels, chicken skin, and hard crab debris I have actually observed all these things) usually takes one of two forms.
“I’m just feeding the crabs.” In summer (but not winter) the crabs will, indeed, consume some, but not all, the fish carcass. Most of it will rot (undergo microbial decomposition), consuming dissolved oxygen, and the nutrients nitrate and phosphate will be returned to the water to foster the growth of suspended algae. The algae grow very rapidly and cloud the water. The cloudy water from the rapid algal growth prevents light penetration and the growth of sea-grass, or SAV (Submerged Aquatic Vegetation) that provides food and sanctuary for many marine organisms. Because there aren’t enough animals to eat all the suspended algae, and because the algae are short-lived, many of them die and then settle to the bottom. On the bottom, microbes decompose the algae, consuming dissolved oxygen in the water and stressing animal life.
Things can get really bad, especially in summer when the water is warm. The solubility of gasses like oxygen decreases with increasing temperature, so the warm water can only contain small amounts of oxygen. If it is very still, atmospheric oxygen is not mixed into the water by the wind. In the worst case, the water becomes stratified, or layered, with less dense (fresher or warmer) water at the surface and denser water beneath, out of contact with the atmosphere but in contact with the organic-rich bottom mud. Under these circumstances, oxygen levels can fall low enough to cause fish kills. If you want a vivid picture of what happens in the bottom of our creeks, jam a stick in the water, pull it up along with a bit of the muddy bottom, and take a whiff!
The crabs’ problem is not lack of food there is plenty of food naturally present in the water. The crab’s problem is not enough habitat like SAV and marsh grass beds, and the killing of egg-bearing females (sponge crabs). Think of it this way. Is all the nitrogen and phosphorous in that rockfish carcass eaten by crabs, which are then caught and removed from the water? No. Most of the nitrogen and phosphorous is added to the water column by the rotting carcass. More nitrogen and phosphorous is, of course, continually being added to the creek from your drain-field, which is merely processing the delicious rockfish (and everything else) you ate for dinner.
“I’m just returning it to the sea” is the other common rationalization for people who throw fish or crab debris into the water. True, you are returning it to the sea, but not to where it came from. The organism probably came from the open Bay, and throwing it into a small creek overloads the ability of the small body of water to process it. Disposing of the debris in a landfill or compost pile removes the nutrients from the water. The fish/crab debris didn’t come from the creek, so don’t add it to the creek. Once the organic material is out of the water, don’t put it back in.
Grass clippings are an especially onerous form of waterway pollution. Every gardener knows that grass clippings added to a compost pile provide nitrogen. The rapid decomposition of the grass raises the temperature in the compost pile, killing undesirable seeds and microbes. Grass clippings also make great fodder for herbivores, because they are so nutrient rich. Throwing (or blowing) grass clippings into the water is just like throwing fertilizer into the water. Composting is an easy and useful alternative.
If you are in the habit of using the creek as a personal garbage pit, remember that you are breaking the law every time you do so. You are also consciously contributing to poor water quality. As you head for the creek with your trash, ask yourself: If I lived in downtown Heathsville would I carry this out and throw it in the gutter? The waterways will be better off if all of us treat them as treasures, not as convenient sewers.