The fourth treatment was the soft-brush ground gear and comprised 6–mm Ø Dyneema TM braided rope alternately threaded through 74 polyurethane floats (60 × 90 mm)and 74 lengths (260-mm) of 4-mm stainless-steel chain, with another 74 such chains suspended (via two cable ties) singly from each float (Table 1, Figs. 2b and 4d)