Readers of my column know that invasive, non-native species can pose serious problems for natural ecosystems. During the period I was Vice President of the Catalina Conservancy some of our biggest ecological issues threatening the island's native systems were the introduced pigs and goats, and a myriad of non-native plants from far-away places such as Europe, Africa, South America and Asia. Approximately one third of the plant species on the island are non-native, although not all of them pose significant threats.
In my 43 years of diving Catalina waters the biggest threat to our native marine flora is surely the highly invasive Asian seaweed Sargassum horneri (formerly S. filicinum) which I call "devil weed." This species was first detected in Long Beach Harbor in 2003 and then here on the island in the winter of 2005-06. Its appearance in southern California waters has apparently been traced to a single commercial ship leaving a port on the Seto Inland Sea in Japan. Since that time it has spread northward into the northern Channel Islands and south all the way to Guadalupe Island, far off Baja California. It has saddened me greatly to watch all my favorite dive sites here on Catalina deteriorate because of this alien invader.
At the time, warnings were issued by scientists who were concerned about its potential to spread, but little was done. A Sargassum horneri Working Group was formed back in 2009, but soon realized it was already too late to eradicate this invader from southern California waters. Instead they focused on monitoring its spread, studying its effects and recommending that a rapid response plan be devised to fight future invaders. I think it would be a big help if readers of this column contacted our state's Department of Fish & Game Marine Division (email@example.com) to let them know what a problem this species is. By the way, the CDF&G was recently renamed the Dept. of Fish & Wildlife, a welcome change in my eyes which should put a greater focus on protecting all our native species instead of just managing those which are hunted.
During the summer and fall of 2006 water temperatures as deep as 150 ft were extremely warm for several weeks, causing our giant kelp forests to largely disappear. No longer shaded by the kelp's canopy, and able to deal with the low nutrient levels associated with the warm temperatures, Sargassum horneri proliferated into the winter and spring. Much of the dive park looked as if fields of tall wheat were growing. And like most agricultural fields, the vegetation was a virtual monocrop. The Sargassum dominated the substrate, outcompeting the native algae for attachment and therefore light and nutrients. In some areas the Sargassum grew as tall as 20 ft (6 m).
The ecological devastation wrought by this invasive that season prompted me to contact representatives at CDF&G regarding my interest in trying to control this threat. I was told it would take about four months to obtain a permit to remove it since divers can only harvest 10 pounds of wet weight of seaweed per person per day, and that requires a fishing license. By the time a permit was issued, the Sargassum would have reproduced and we would be too late.
The next few summers exhibited cooler than average water temperatures. The giant kelp thrived, its canopy still luxuriant even during the early fall. With healthy kelp forests in those years, the Sargassum was not as great a threat and control efforts were not as urgent. However, this summer and fall water temperatures once again shot up to well above average and much of our giant kelp has succumbed to the lack of nutrients associated with high temperatures. The Sargassum is again beginning to proliferate and will undoubtedly be a problem over the winter and spring.
Nearly two months ago I anticipated this and initiated contact with representatives at CDF&G to try to obtain a removal permit. It took weeks before I even got a response to my inquiry, and the reply was to say that someone would be in touch regarding what CDF&G needed to consider my request. Three weeks later I received an e-mail outlining the information they needed from me to even consider my request. I felt like I was applying for a major financial grant from a government agency rather than trying to assist the Department in coming up with ways to try to control this noxious (sea)weed.
I worked long and hard to try to get the Dive Park designated as an official marine protected area (MPA). That status was conferred on January 1st of this year. The new MPAs were the result of legislation known as the Marine Life Protection Act. I have quickly discovered that removal of ANY species from an MPA, whether it is native or non-native, requires a major effort in scientific salesmanship to accomplish.
This has certainly caught me off guard. If the intent of an MPA is to preserve an assemblage of native species that can then serve for scientific study and to re-establish populations in adjacent unprotected areas, why can't we quickly get permission to control an obvious and serious threat to those native species from an invasive one not even native to the New World? The language in the MPA description states that "take of all living marine resources is prohibited" unless otherwise stated for each MPA.
Now this illustrates what I consider to be a very significant error in the language of the MLPA and MPA descriptions. No distinction is made between native species and non-native ones. I find it difficult to fathom how no one thought to make this distinction! Way back in 1972, before the federal Endangered Species Act was passed, the Wrigley and Offield families formed the Catalina Conservancy. In its Articles of Incorporation was a clear mandate to protect not only native species, but also native ecosystems... and that distinction gave us the mission of ridding the island of the most pernicious non-native invaders, be they plant or animal. If only our legislators in Sacramento had been as wise.
Yes, I know. This week's column was not written in my usual humorous vein. Although I prefer not to, I can get very serious about issues I consider to be of importance. Fortunately I can mellow a bit when I take on my long-term perspective. In a few billion years the Sun will nova and our beloved planet and its oceans will be vaporized and everything turned into crispy critters. Despite the advances of modern medicine, I doubt I'll still be here then. However, as one of my favorite song writers Phil Ochs wrote "Can't add my name into the fight while I'm gone... So I guess I'll have to do it while I'm here." Or as poet Gary Snyder said in the Four Changes: "Knowing that nothing need be done, is where we begin to move from."
© 2012 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. You can also watch these episodes in iPod format on YouTube through my channel there (drbillbushing). Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!
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Healthy reef with a biodiverse mix of native algae; low diversity monocrop-like infestation of S. horneri;
close up of immature Sargassum and Sargassum attached to a pebble making it capable of invading
even ocean floors with soft sediment.
This document maintained by
Dr. Bill Bushing.
Material and images © 2012 Star Thrower Educational Multimedia