Rising temperatures and aquatic invasives affecting global fisheries

The following piece was sent to us by Pucci Foods, a seafood company.  Rising ocean temperatures have begun to affect our oceans in many ways, some we are just beginning to comprehend.  Rising carbon dioxide in the atmosphere is further compounding the stress on the diverse ecosystems in the oceans by increasing the pH levels of the waters.  All of this affects our global fisheries.  While fisheries have been squeezed by unsustainable fishing practices of many companies, some have begun to implement healthy fisheries management practices.  Indeed the climate movement could use the support of this industry.  Having the companies communicate about how climate change affects their industry is critical.  While this entry is not an official endorsement of any company, we urge readers to take note of this important issue.  The original piece can be found here. 

There are three little words that strike dread in the heart of anyone who relies on the natural resources of our oceans: aquatic invasive species. Life in our oceans has evolved over millions of years to build the beautiful ecosystems we see today. Each creature is well-suited for their watery niche – if they they don’t adapt they die. Each animal and plant has adapted to live in a very specific environment. Each one is adapted to a unique set of prey, predators, and environmental conditions, such as temperature and salinity. When removed from their habitat and placed in a new one, they either thrive or expire. Unfortunately for many marine ecosystems, aquatic invasive species have taken hold and infringed upon native habitat.

Invasive green crabs, aided by warming ocean temperatures, are wreaking habitat and economic destruction on the East Coast. 
Image courtesy of SERC.

Aquatic invasive species are a growing problem. With the fleets of ships and shipments traveling from one country to another, there are endless ways for little critters to hitch a ride. A common mode of transport is the ballast water of a ship, as it is sucked up in one port and expelled in another, releasing any number of invasive larval invertebrates and fish. Their spread is unpredictable and some of our environmental conditions are able to keep them at bay. However, we are now learning some disturbing news: the spread of some aquatic invasive species may be facilitated by warming ocean temperatures associated with climate change.

The European Green Crab

When aquatic invasive species manage to enter a new ecosystem, they don’t have the same predators that have evolved along with them. If they can survive the environmental conditions, then they have free reign to grow, multiply, and begin devouring native species with nothing to hold them back. The East Coast of the United States is being attacked by one such aquatic invasive species: the European green crab. This little crab is well-known to ecologists here in California – it has also reached the West Coast, but to a lesser extent.

The seemingly harmless green crab exists in marine habitats with harmony along the Atlantic coast of Europe and northern Africa; here in the United States it is an insatiable predator that has steadily been eating it’s way through our valuable shellfish. When first introduced to the U.S. over 100 years ago, most likely transported by an unsuspecting Trojan Horse in the shape of a ship, the green crab was not so terribly bad. They invaded – but we were quick to respond with effective management and squelched them before they got out of control. Little pocket populations persist along the West Coast and definitely do our native species no favors, but the green crab has so far been unable to establish a destructive stronghold on our coast.

Invasive European green crabs have been found on both the West and East coasts, but is wreaking far more havoc along Atlantic shores.
Image courtesy of Marine Invasions Research Lab/SERC.

Unfortunately, it seems like times are changing. The population of invasive green crabs has exploded along the coast of Maine and are decimating shellfish populations, a loss that will likely cost the state millions of dollars. The bivalve shellfish industry is Maine’s third most profitable fishery and the green crabs have been gobbling up the “spat”, or juvenile shellfish, like there’s no tomorrow. Efforts to eradicate them have thus far proved fruitless. As fishermen grow more desperate, the crabs are simply growing fatter and multiplying. In some areas, up to 90% of clam flats no longer have any harvestable clams.

The devastation wrought by the invasive green crabs will cost fishermen their jobs and could impact the state’s tourism, as Maine is well known for it’s abundant and delicious seafood – which may no longer be available. Coastal embankments are crumbling where the green crabs have been burrowing in their never ending search for food, causing a devastating erosion process.

Warming ocean temperatures are to blame

So why has the European green crab suddenly been able to outsmart us to such an extent after more than 200 years in residence? This tremendous explosion in numbers is very likely the result of warming ocean temperatures. The sea surface temperature in the Gulf of Maine reached its highest temperatures in over 150 years during 2012. We’ve known for some time that green crabs have difficulty molting and reproducing in water colder than 10 degrees celsius, which is partly why they have not been able to invade the West Coast as effectively – at least not yet. The invasive crabs are well-adapted to warmer temperatures that more closely match their native range. They are able to spread faster and reproduce more quickly, entering areas that before were too cold for them, and increasing their invasive range.

Sea surface temperatures in the Gulf of Maine reached the highest on recorded in 150 years in 2012. 
Image courtesy of TalkingFish.org

It is a side effect of climate change that is unprecedented, one that we were not prepared to handle. Warming ocean temperatures can not only make a less favorable habitat for our native species, but it can make conditions more favorable for aquatic invasive species. The green crab has always required little management on both coasts, but with warming temperatures, we have no real management method in place for a booming population of the invasive crabs.

Fishermen, regulators, and scientists are scrambling to find a way out of the green crab pickle. There is such a massive number of the green crabs that an effort to catch and eradicate them completely would have to be on a grand scale. There is no established economic market for the crabs – the large ones can provide nutritional food, but most are too small to be eaten. They can be used as compost, but as of now they have little economic value. Gathering all these crabs has proven to be a daunting task, considering the sheer numbers and range. Any type of chemical pesticide would damage non-target native species as well.

Of course ocean conservationists and researchers are trying to discover what effect warming ocean temperatures might have in tropical waters. If our cold, resilient east coast has suffered so much from one little invasive crab, what will be the effects of warming ocean temperatures on delicate coral reef ecosystems? As the center of marine biodiversity, South Asia is one very important area of concern when we are considering how warming ocean temperatures will affect coral reefs. Corals are already sensitive to even minuscule temperature changes and have the terrible tendency to bleach when under stress, or expel their zooxanthellae (symbiotic algae that provides food for the coral). If the stressor goes away, the corals are able to resorb zooxanthellae and they will survive. But if the stressor continues long enough – such as a persistently warmer ocean – the corals eventually die. As coral reefs provide for countless coastal communities in South Asia, a warmer ocean could have economically devastating effects.

What does the future look like?

This is yet another downside to the climate change dilemma. What other aquatic invasive species will thrive in the new conditions our oceans are undergoing? How much economic impact will we see in the coming years from the spread of invasives like the green crab? How can we manage to adapt our fisheries management strategies to compensate for the unforeseen effects of climate change? In time, the West Coast could suffer a similar boom in green crabs, bringing habitat and economic damage with it. Our coasts are more nutrient rich than the Atlantic and there is even more potential for native species to fall victim to aquatic invasive species.

Hopefully we will learn from the crisis on the other side of the country and investigate what management procedures can be set in place in case something similar happens. Scientists are struggling to understand what changes in the marine ecosystem will be brought on by climate change, but these changes are difficult to predict and it will be even more difficult to implement fisheries management changes on the basis of predictions.

This is why it is so important to make the change now. Our carbon emissions are affecting marine ecosystems in complex ways that we are only beginning to understand. The best way to mitigate these effects is by starting at the source and working to reduce our carbon footprint. Each and every person has a part to play, and together we create a brighter future. We urge you to support businesses that strive to keep our oceans healthy, such as Pucci Foods.

 

Some Examples of Climate Change Illiteracy

This entry has been cross posted at Reporting on a Revolution.

Following on the heels of my previous post in which I attempted to put up arguments in favor of human induced global warming, a stark and scary reminder of what I am up against. A couple of example of climate change illiteracy I picked up from the blogosphere.

This one is from Climate Progress and an interview with Barb Davis White a republican who is running for the 5Th Congressional District in Minnesota.

WHITE: My name is Barb Davis White and I’m running for the 5Th Congressional District against Keith Ellison for the United States House of Representatives, which is called Congress.

ROMM: Where are you on global warming?

WHITE: Well, global warming really has not been proven. There are 30,000 scientists, including Al Gore’s professor, from Princeton, who says that we are now in a cooling stage. And ev-every — also every other climate that has been warmed had better grapes.

ROMM: So you don’t believe in global warming and you don’t think that people caused it.

WHITE: No, I think global warming is a scam. I think it’s a scam to put taxes — more taxes on us, and it’s called carbon taxes. Our environment has never been so clean, and if we want to push global warming, let’s push it on China, where the smog is so thick that you almost need a helmet to breathe. Let’s push it on Africa and see how they adapt to it, because they’re not going to.

And from Pharyngula who got it from Diatomaceous Earth. A letter sent to the local paper in Fargo, North Dakota. Is Fargo really this eerie?!!

When God sent the rain on this Earth for 40 days and nights, all this water had to go someplace so the Earth would be dry again.

Remember, God is the Creator and controls the universe.

God tilted the Earth from its original position and caused all the excess water to rush to the poles, and there he instantly froze the water into the ice formations that exist today. Time is ticking down on God’s time clock.

With all the nuclear bombs that are made and stored for the fast-emerging last battle, this Earth would burn up when these nuclear bombs are set off.

We are not creating global warming – God is tipping the Earth back to its original position on its axis and thus getting all this ice to get ready to move and extinguish the nuclear destructive fires man will create.

Is this being taught in church or at home.? Where do people learn this? Unbelievable! I have come across the first type of illiteracy i.e. the Barb Davis White type in India, but so far not the second. We can find humor in this but it is a rather depressing example of how a religious fundamentalist education can warp your world view. Have you experienced such extreme views in India?

Sea Level Rise and Your City

This entry was originally made on Reporting on a Revolution on April 16, 2008

From my Geology News Feed a link to a pretty cool application for assessing the impact of sea level rise on coastal areas. The application written by Alex Tingle of Firetree.net uses NASA elevation data and the Google Maps API to create dynamic maps of flooding. I played around a little with Mumbai. It’s tempting to run a disaster scenario. Just choose a sea-level rise of 10-15 meters and watch the city go under water. But the results are not very surprising and not too realistic either. This massive a rise in sea level is at the extreme end of the climate change and sea level rise scenarios possible if the Greenland and West Antarctic ice sheet completely melts. May happen but unlikely for the next couple of centuries.

 I wanted to find out whether the elevation data underlying the application was fine enough to depict subtle variations in topography and the effect of a small change in sea-level. I used just a 1 meter rise in sea-level. The resulting map impressed. The flooded areas were restricted to the low-lying mudflats and mangroves along the Panvel, Thane, Mahim, Gorai and Vasai Creeks. The rest of the city was unaffected, which is to be expected since the land surface of Mumbai is hilly in places or has been raised by several meters during land reclamation projects. Climate scientists give scenario based range of values for sea-level rise this century and a sea-level rise of 1 meter by the end of the century is a distinct possibility. This would mean large areas of Mumbai and surrounds will be at risk. Image below shows Mumbai and its suburbs and exurbs. Pink areas are the built up concrete jungle, lighter green is land vegetation, blue is water and dark green-brown areas are tidal mudflats and mangroves.

Mumbai City and Environs

A 1 meter sea-level rise will affect these mudflats the most. Yet at places I have marked with arrows near the Panvel and Thane Creeks, pink is intruding upon the dark-green, which means construction is eating up those low-lying areas. All these new constructions are raised a few meters above the original surface and that may protect them against a future sea-level rise. But there are other factors at play and these were demonstrated with terrifying clarity during the flooding by the Mithi river of Bandra-Kurla complex and adjoining low lying areas on July 26-27 2005. As shown by arrows near the Mahim Creek area which trace the Mithi river, mudflats and mangroves were built upon and the river channel reduced to a narrow drain. Since no natural holding areas for the water such as mangroves were left, a combination of high rainfall and high tide led to water level rising up several meters and inundating buildings and even the airport.

But we never seem to understand and learn from history. The same mistakes are being repeated at Panvel and Thane Creeks. When I was growing up, one of the great pleasures of driving to Mumbai from Pune was the gorgeous landscape after Panvel, all those unspoiled tidal channels, creeks and mudflats and mangroves until you crossed the Vasai Bridge. Today that area is an ugly sight. Mud-flats and natural drainages are being filled up and we may soon have constructions coming right up to the banks of the main Panvel tidal channel. The events of July 26 2005 showed how even at present sea-level, bad urban planning can led to severe flooding. The consequences of just one meter rise in sea level can be difficult to predict and may be more damaging than anticipated if you start thinking of its effects on tides and coastal erosion. And add to that are monsoons and storms which may become more powerful as oceans warm up over the century leading to water pileups and storm surges several meters high locally. I really don’t know if the new constructions are being built with future sea-level rise in mind but every time I drive past Panvel all I see is more constructions on those mud-flats. There is no doubt that we are putting the people who will live adjacent to these creeks and channels at a very high risk of flooding and storm damage.