By Bob Ferris
I have always liked sea otters—in part—because they are the quintessential keystone species or critters that materially determine some of the character of their habitat for them and others. And now as new research emerges about the trophic cascade effects (i.e., the side benefits of having top predators present) associated with the otter’s control of sea urchins and the resultant macro-algae (kelp) growth, we also begin to understand that they are effective and needed warriors in the battle against climate change and ocean acidification. How? Kelp forests—like terrestrial forests—sequester carbon and CO2 is one of the leading causes of these phenomena affecting our air and seas.
This almost obvious finding leads me to speculate: If urchins need the otter’s controlling influence for us to have robust aquatic forests, what are the terrestrial equivalents? To begin to answer this question, let’s look at what sea urchins actually do. Urchins don’t just eat large kelps such as bladder, boa and bullwhip kelp, they destroy the holdfasts which are essentially kelp “roots” and clearcut themselves into the oceanic pastures—known as urchin barrens—they most like to graze. Urchin dominated “marine-scapes” look like denuded plains. And without the three-dimensional volume provided by these large and long kelps they lack the structure and escape habitat needed for young fish (including salmon, smelt and rock fish) and a host of other sea life. They essentially become oceanic deserts—great for urchins but not for kelp forest denizens or overall biodiversity.
1) A mischievous young child, esp. one who is poorly or raggedly dressed.
2) A goblin.
When we look at the current and past large grazing guild for Cascadian forests and wildlands we have elk, deer, bison, caribou, moose, big horn sheep, mountain goat and the two new-comers cattle and domestic sheep. Who are the sea urchins in this equation and why? Well, deer and elk as well as the other less plentiful native ungulates do not have a history of knocking ecosystems irreparably out of whack—particularly in the presence of wolves and other apex predators. The same cannot be said, however, of cattle and domestic sheep.
Why are cattle and sheep different? For one thing it is a numbers and carrying capacity issue. Cattle and sheep—particularly on public lands—are brought in at and purposely over-stocked at levels that could not be supported year-round. This bovine and ovine host, therefore, eat more, faster than their natural counter-parts ever could. They are essentially like the guests who visit in large numbers, eat you out of house and home then move on leaving you starving. Additionally, they are critters that evolved in the Old World rather than North America in systems more prone to annual plants rather than perennials.
Bison exhibit a stronger preference for the perennial grasses that form the prairie matrix, and they are strongly attracted to open landscapes during the growing season. Cattle include more forbs in their diet, and they use wooded areas and riparian zones more intensively. From: Comparative Ecology of Bison and Cattle on Mixed-Grass Prairie.
Cattle grazing habits and regimes as well as the spread of European annuals through seeds in cattle droppings have altered vegetative make ups. This annual versus perennial issue is a large one—particularly as we look at carbon sequestration. Perennials sequester more carbon than annuals because their root structures are more substantial and longer-lasting and more roots in the ground means more below surface carbon. Add to the root structure loss, the flatulence factor from too many cattle farting methane—a greenhouse gas—by the hot-air balloon full and you have another rationale for adjusting your dietary choices.
And for those thinking that cattle and bison are functionally the same. The cattle’s use of wooded areas and riparian habitats not used by bison indicates an encroachment into the elk and deer realm and a departure from the co-evolved, ecological niche separation exhibited by the bison. This direct competition with elk and deer for space and food makes the alliances between hunters groups such as the Rocky Mountain Elk Foundation and Safari Club International and ranchers all the more puzzling as the livestock industry’s interests are clearly in conflict with those of wildlife including game species and fish. And this further impact on native wildlife species cements cattle and domestic sheep as land urchins.
So what should we derive from all of this? First, efforts to broaden and emphasize sea otter restoration all along Cascadia should be re-accelerated and expanded particularly along the coasts of Oregon and Washington. We need also to open our eyes on cattle and sheep grazing—particularly on public lands—and honestly and realistically assess the benefits as well as the full spectrum of implications relating to federal ranching subsidies, wildlife impacts, and compromised ecological services such as clean water and carbon sequestration. And lastly we need to continue to work towards ecological literacy so that more people come to understand these complex ecological relationships for a host of natural systems and critters from otters to orcas and from wolves to wolverines. They all help us keep it wild.