To provide a strong security service in Wireless Sensor Networks (WSNs), cryptographic mechanisms are required. Generally these security mechanisms demand intensive use of limited resource, such as memory, and energy to provide a defense against attacks. Monitoring the behavior of nodes and detecting risks according to these behaviors, and then taking decisions based on these measurements generally requires the use of a trusted Key Management scheme. In this paper we compare two existing security key management schemes that were designed for use in mobile ad hoc networks: "An overlay approach to data security in ad-hoc networks" authored by Jorg Liebeherr, Guangyu Dong, and "A hierarchical key management scheme for secure group communications in mobile ad hoc networks" authored by Nen-Chung Wang, Shian-Zhang Fang. Then a Hybrid Security Key Management Mechanism designed for use in the marine environment is proposed. This scheme focuses on reducing the memory storage of keys, using a leader node that is responsible for both the node joining and the node revoke processes. This security mechanism is implementing in real time on the Waspmote sensor platform.