Sunken Warship Brings Sea Life To Ocean Waters Off San Diego’s Mission Bay
Thursday, November 5, 2015
The wreck of the Canadian destroyer Yukon is a magnet for divers looking for adventure near the San Diego coast. The ship also attracts a wide range of marine life. Scientists are documenting the area to help understand how the wreck is affecting the underwater environment.
"Then you start seeing, especially if you have lights, these little riots of color." - Barbara Lloyd
Barbara Lloyd's boat bobbed up and down in relatively calm ocean waters. She was about a mile west of Mission Beach. The Belmont Park roller coaster is easy to see and so is La Jolla to the north and Point Loma to the south.
"This is the Yukon and it is an artificial reef that's about the size of a football field," Lloyd said. "So that's quite a bit of distance, most divers only dive about half of it."
The San Diego Oceans Foundation spent $250,000 to bring the former Canadian destroyer to San Diego 15 years ago. The ship was cleaned up and sunk in about 130 feet of water. Lloyd leans over to Michael Bear. They are preparing by talking about the upcoming dive.
"Descend on the stern buoy and let's just do our check there to make sure all of our gear is set and that we're all ready and check our air and everything right," Lloyd told Bear.
Bear is an experienced diver and underwater photographer and he shares Lloyd's passion for the underwater realm. On this day, the pair hoped to photograph the ship's propellers.
"And then when we get to the end where the propellers are we can stop about mid-ship and then let's come up on the hull," Lloyd said.
Lloyd and Bear slip into their wetsuits, check their equipment and slip overboard. The current is the first thing Lloyd noticed, but it is a short trip to the descent line and soon the pair are heading down.
The underwater world
"And so you'll go from this really clear water, and you think this is going to be the most amazing dive," Lloyd said. "Sometimes it is. Then all of a sudden you go into this dark green murky water."
With cameras rolling, the divers plan to record how sea life is doing on the hard surfaces of the Yukon, as well as the nooks and crannies of the ship, but it takes a minute or two for a diver's eyes to adjust.
"Then you start seeing, especially if you have lights, these little riots of color," Lloyd said.
Her eyes lit up as she recounted a recent dive and the colorful palette that revealed itself.
"They could be the strawberry anemones and they're brilliant. Or the white anemone, there's a couple different species of these white anemones that show up. So you'll have greens, and pinks, and whites, and browns and rusts," Lloyd said.
There was quite a change at the Yukon wreck site over the past 15 years.
Bear remembers. He worked with the crew that cleaned up the warship before it sank and he was also among the early divers.
"In the first few months, you don't notice that much," Bear said. "But the remarkable difference comes a year or two down the road when you haven't dived it in a while. And you dive it. And all of a sudden you're noticing sea life, where there was not sea life before. And that's the truly remarkable difference."
Bear wants to help document the change since the warship was sunk. The ongoing citizen science survey allows Bear, Lloyd and recreational divers to share their underwater photography. The video and photos will be collected and curated.
"You definitely are going to notice differences over time. And that's part of the purposes of the study, is to scientifically track which species are leaving and which are coming in," Bear said.
Some of those species wandering through the wreckage are more than a bit surprising. A diver recently captured something on film that is not common in these cool ocean waters. It is called a salp chain.
"It's a gelatinous colony animal that drifts with the currents," Bear said. "And they just happened to be on the Yukon as they were photographing something else and this salp chain sort of photo-bombed the photo and they got a photograph of that species logged in our data base."
Yukon's impact is debated
One reason the Yukon attracts such a variety of different plants and animals is that the ship stands in stark contrast to the sandy ocean floor that dominates the coastal shelf off Mission Beach.
"The artificial reef provides lots of structure for lots of invertebrates and fish to live on," said Ed Parnell, a Scripps Institution of Oceanography researcher. He conducted the first underwater study of the Yukon a few years after the ship sank. "So its kind of an interesting recreational area for divers and an important area for recreational fishermen as well to target those species that they're after."
The wreck is clearly marked on the surface making it easy for fishing boats to drop anchor here. That feeds a debate about whether recreational and commercial fishing saps the potential impact artificial reefs can have on local fish populations. There is also concern about long-term environmental impacts.
"But as it slowly deteriorates, a lot of the metals, the fouling paint that wasn't completely cleaned off of it," Parnell said. "As well as the PCB's in the bulkheads, PCB's don't break down. It's a legacy pollutant. The fate of those materials and that food web out there on that shelf is not known and its not well studied."
Parnell expects the Yukon to be part of the local seascape for decades. Tracking and recording the life around the ship will help scientists better understand the vessel's impact, over time.
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