Date of Award

5-2023

Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)

Department

Marine Sciences and Technology

First Advisor

Michael Tlusty

Second Advisor

Robert Chen

Third Advisor

Kimberly Hamad-Schifferli

Abstract

Seaweed aquaculture is a fast-growing industry, both in the United States and worldwide. In a typical operation, a grower operates an offshore plot which consists of a grid-like pattern of submerged “long line" ropes. Kelp is seeded onto these ropes and grows downward, nurtured by the flow of water and nutrients that passes over it. If this structure of underwater ropes is compromised, either by floating debris or an animal entanglement, it can cause significant economic damage to the operation. There is also growing concern towards protecting marine mammals from becoming entangled and injured in aquaculture systems. Due to the nature of seaweed farming, an aquaculturist might only visit their plot every two - three weeks. This intermittent schedule of visits contributes to the need of a near real-time monitoring system. This thesis describes the design and fabrication of a sensor system to monitor the physical integrity of the underwater ropes used in seaweed and other aquaculture operations, so that growers can be remotely notified and rapidly respond to incidents occurring on their offshore plots. The final sensor design integrates a reusable "weak link", a piezoelectric sound projector, a hydrophone, and LoRa radio communication technology. As tension is added to the rope by an entanglement or other stress event, the modified weak link activates, generating an acoustic frequency which is picked up by a hydrophone monitoring buoy and transmitted to shore. This sensor can be added to an existing long line rope without needing to cut the rope, and the break-link can be scaled to fail at different tension forces. Preliminary testing shows the acoustic range to be at minimum 60 feet from node to monitoring buoy.

Comments

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