University of Central Florida Undergraduate Research Journal - Preventing Introductions to Sustain Healthy Ecosystems: Establish Eradication Protocols for a Popular Aquarium Seaweed
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Materials and Methods

Chaetomorpha was purchased from 3 different retailers: (internet), World Wide Corals (local retail), and Top Shelf Aquatics (local retail). Once purchased, each algal clump was analyzed and placed into a 10–gallon aquarium with 31ppt artificial seawater, the optimal salinity for Chaetomorpha (Xu and Lin 2008). All three batches of Chaetomorpha were classified as C. linum. The artificial seawater was a mixture of deionized water and Instant OceanTM sea salts. Each algal batch was exposed to a 12– hour dark/12–hour light cycle for a minimum of one week before the experiments. Pure, experimental–grade acetic acid was purchased from a chemical supply company and concentrations were mixed with 31ppt seawater to determine the minimum effective dose. The trials were conducted at room temperature (25°C) and exposed to standard laboratory lighting of overhead fluorescent bulbs (maintained average illuminance: 400 lux).

C. linum was cut into 1 and 10 cm fragments with a single edge razor blade. The fragments were cut on wet paper towels moistened with salt water to prevent contamination and dehydration. Once cut, the fragments were quickly placed into 55 mm diameter sterile plastic petri dishes with the appropriate acetic acid concentration. Controls were placed in sterile plastic petri dishes with artificial seawater. Forceps were used to transport fragments. The fragments submerged in acetic acid concentrations remained in closed petri dishes for the planned exposure time.

Once the exposure time was reached, each fragment was removed from the petri dish, submerged in deionized water for 5 seconds, and placed in a clean petri dish with 10mL of 31 ppt artificial seawater. After the trial, petri dishes were randomized throughout the laboratory and exposed to 24–hour/day light cycle and tracked for survival over time.

Trials 1 and 2

Trials 1 and 2 tested a total of 1800 fragments (900 × 1 cm, 900 × 10 cm) of C. linum against 5 concentrations of acetic acid and 9 exposure times. Survival was tracked at 24 hours, 48 hours, 2 weeks, and 5 weeks as shown in Table 1.

Trial 3

Based on the results of Trials 1 and 2, we conducted Trial 3 to narrow the effective concentration range (Table 2). For Trial 3, we tested 360 fragments (10 cm) of C. linum against 6 treatments of acetic acid at 6 exposure times. Survival was tracked for 72 hours.

Trial 4

Based on the results of Trials 1 – 3, we conducted Trial 4 to test the efficacy of store–bought acetic acid (cooking vinegar) on fragment survival. 60 fragments (10 cm) of C. linum were tested with 5 different commercial vinegars (5-6% diluted acetic acid) at 2 exposure times (Table 3). Survival was tracked for 24 hours.

Survival in all cases was analyzed using a dissecting microscope. If one single cell was still alive, the entire fragment was considered alive because proliferation remained possible (Odom and Walters 2014). A fragment was characterized as dead when all cell walls were shriveled and detached from the outer membrane. If classified as dead, we disposed of the C. linum fragments and petri dishes. If the C. linum was still alive, the water level and salinity of the petri dishes was maintained throughout the monitoring period by adding deionized water. Once the monitoring was complete, all living fragments were disposed of and water from petri dishes was strained with a 1mm mesh net to prevent accidental introduction into the environment.

Results >>