The species interactions are crucial for understanding the food web dynamics in the ecosystem, particularly under a changing environment. Though there have been many suspicions that species interactions may mediate their response to environmental variability, the empirical evidences are limited. Such causal relationships are often difficult to detect with classical statistics. Here we apply the convergent cross mapping (CCM), a method based on nonlinear state space reconstruction that can distinguish the weakly-connected dynamic systems, to disentangle the environmental (bottom-up) and biological effect (top-down) in the cod-invertebrate coupled relationship.