42 ± 23.46). There was no significant difference in time until death between the two concentrations of bile derivatives tested (H1,16 = 0.099, p = 0.753; Table S4). Overall, six out of the 25 sea stars injected with Oxgall initially exhibited signs of the effects of bile injections (i.e. loss of turgor and localized lesions at the site of injection) within the first 24 h, but eventually recovered after 7 days of observation. Among the COTS injected at different sites with a single dose ( Fig. 1A, B; Table S5), Bile Salts No. 3 (28.95 ± 4.08 h) GW 572016 resulted in significantly more rapid death after injection
compared to Oxgall (57.98 ± 12.95) (F1,32 = 21.609, p = 0.019; Table S6). Even when Oxgall concentrations were doubled, proportion Ruxolitinib mouse of dead COTS after 48 h remained at 60% ( Fig. 1D). The differences observed between Oxgall and Bile Salts No. 3 may be due to the composition of these derivatives. Bile Salts No. 3 is composed of sodium cholate and sodium deoxycholate, which are known detergents that lyse cell membranes after contact ( Rolo et al., 2004). Bile Salts No. 3 undergoes a refining process that removes lipids and reduces the pigments in the bile, thus
making it a useful component of selective broths and has higher potency even at lower concentrations ( Oxoid, 2014). There was no significant difference in mortality of COTS injected at different sites (p = 0.891; Fig. 1, Table S2). The highest proportion of dead COTS after 48 h (100%) was achieved by injecting COTS in the proximal region of the arm where digestive and reproductive glands are situated ( Fig. 1A, B). Mortality rates were lowest (60%) when COTS were injected in the central disk with oxgall at 6 g l−1 and 12 g l−1 ( Fig. 1B, D). Mortality of sea stars injected in the central disk mainly Vitamin B12 depends on which organ the tip of the syringe needle hits upon injection. Chemicals can be easily
discharged by the sea star if injected in the cardiac stomach or near the mouth. Time to death was also most rapid in COTS that were injected in the base of the arm (22.68 ± 2.91 h) and slowest in sea stars injected in the central disk (59.39 ± 19.22 h), however these differences were not statistically significant (F1,32 = 7.511, p = 0.066; Table S6). The newly developed hybrid gun was the most consistent and effective of all three-injection guns, killing all COTS in 20.49 ± 0.18 h (Fig. 2). The Simcro® plastic syringe was also effective, killing all sea stars in 29.45 ± 4.66. However, the long needle fitted to this gun can overshoot during injection and release solutions outside the sea star’s body. The classic metal DuPont™ Velpar® Spotgun® only killed one individual, which lasted 53.78 h before dying. This finding confirmed that the large holes created by the traditional spray gun allow chemicals to leak back into the ocean and it is one of the causes of high rates of COTS survival during control efforts. A. planci injected with 4 g l−1 Bile Salts No.