North American River Otter

River otters are the freshwater cousins of sea otters, occupying a similar ecological role in lakes and rivers. But river otters don't create the same keystone effects. Freshwater systems have different prey bases, different ecosystem dynamics, and different cascade mechanisms. River otters are apex predators in their environments but don't trigger the dramatic trophic cascades sea otters create.

This comparison reveals that keystone status depends on ecosystem context, not just species identity. Sea otters are keystones because kelp forest systems are structured around the otter-urchin-kelp relationship. River systems aren't structured the same way—there's no equivalent cascade waiting to be triggered or prevented.

The business parallel is that identical roles create different effects in different systems. River otters are like the same executive working at different companies—keystone at one, merely competent at another—because the systems they're embedded in respond differently to their presence. Understanding keystone effects requires understanding system structure, not just species capability. Some markets have leverage points where intervention triggers cascades; others don't.