In addition to shifts in overall climate, changing ocean temperatures affect marine organisms, such as dinoflagellates, which are one-celled algae with long, whip-like structures called flagella that let them turn, maneuver, and spin about in the water. Roughly 90% of these algae dwell in the ocean, and about half of them employ photosynthesis to obtain energy. Moreover, the median size of dinoflagellate cysts (the resting stage, which fossilizes) is controlled by the thermal gradient between the surface waters and the deep waters, and thus the magnitude and frequency of available nutrients may have acted as a selective factor in the macroevolution of cell size in the plankton. (In evolutionary biology today, “macroevolution” refers to any evolutionary change at or above the level of species.)
THE WORLD OF PELAGIC MICROBES
Speaking of deep water, microbial activity in the ocean sediment is critical in determining whether particulate organic carbon is recycled or buried. Diverse consortiums of anaerobic microorganisms (primarily bacteria that are able to survive and grow in environments without oxygen) break down organic compounds and thereby mediate the mineralization of organic matter in the anoxic sediments, which have no dissolved oxygen. Concurrently, small changes in temperature affect the efficiency with which organic matter is recycled in these marine sediments.
Taken all together, the pelagic ecosystem of the ocean is by far the largest on Earth. (“Pelagic” refers to the deep waters of the open ocean, as opposed to waters near the shore.) Although its assemblages may be as rich locally as many terrestrial ecosystems, its global diversity is low at both a species and an ecosystem level. There are, however, latitudinal trends in the diversity of pelagic species similar to those in many terrestrial taxa. Nevertheless, the zones with the greatest species richness occur at the boundaries between different types of oceanic water, where dissimilar faunas (assemblages of animals) are mixed together, but the geographical locations of these boundaries are highly flexible and shift hundreds of miles with the seasons.
Meanwhile, on the surface, marine phytoplankton are experiencing competition, predation, infection, and aggregation across distances that range from fractions of an inch to inches. The consequences of these relatively minute interactions, however, influence global processes, such as climate change and the productivity of fisheries.
In active turbulence, patches of phytoplankton, on the order of four-tenths of an inch, have repeatable asymmetry and are regularly spaced over distances of inches to more than a hundred feet. The regularity and hierarchical nature of the patches means that phytoplankton in mixed ocean waters are distributed in dynamic, yet definite seascape topography, in which groups of patches coalesce between intermittent, turbulent eddies.
These patches may link large-scale processes and micro-scale interactions, thereby behaving like fundamental components of marine ecosystems that influence efficient grazing, species richness, initiation of aggregation, and subsequent carbon flux. (“Carbon flux” is an abbreviated phrase referring to the net difference between the sequestration of carbon dioxide through photosynthesis and the respiration of carbon dioxide by such organisms as plants and microbes.)
Moreover, ocean water is typically resource-poor; therefore, bacteria could gain significant advantages in growth if they could exploit the ephemeral nutrient patches that originate from numerous small sources. As it turns out, the rapid chemotactic response of the marine bacterium (Pseudoalteromonas haloplanktis—no common name) substantially enhances its ability to exploit nutrient patches before they dissipate. (“Chemotaxis” is a movement in which bacteria, and other single-cell organisms direct their movements according to certain chemicals in their environment, as when bacteria find food by swimming toward the highest concentration of food molecules or when they flee from poisons.) Therefore, marine bacteria that possess strategies for chemotactic swimming in patchy nutrient seascapes can exert a strong influence on the turnover rates of carbon by triggering the formation of micro-scale hot spots of bacterial productivity.
Phytoplankton accounts for 50% of the primary production worldwide; this diverse group is therefore a major component in the global-carbon cycle. A fraction of an inch of seawater may contain tens to hundreds of species from very different taxonomic groups. Yet, despite their obvious importance, we have limited knowledge concerning the functional role of phytoplankton diversity, or of microbial diversity in general for that matter. In addition to conceptual problems regarding speciation within and among unicellular organisms whose reproduction is largely asexual, it is generally unknown whether or how microbial diversity relates to the function of an ecosystem in ways similar to those observed in more complex organisms.
The tight coupling between microbial diversity and how an ecosystem functions implies that factors, which impair this diversity, are likely to alter the effectiveness of an ecosystem processes. For example, pollution of marine phytoplankton, especially from toxic substances, often manifests itself through a loss of biodiversity. This phenomenon has similar effects in microbial communities in soils, where toxic compounds not only reduce the diversity of natural communities but also lower their functioning and make them increasingly susceptible to further stress. In addition, globalized economics is today driving a lot of anthropogenic change—among it, increasing pollution—in the world’s oceans, such as the Black Sea.
Once described as healthy, various marine predators dominated the Black Sea. By the late twentieth century, however, it had experienced dramatic anthropogenic impacts, such as overfishing, eutrophication through human activities, and invasions by exotic species. (“Eutrophication” is the process whereby chemicals, typically compounds containing nitrogen or phosphorus, are introduced by humans into an aquatic system, where they act as excess nutrients that stimulate excessive growth of plants such as algae.)
As a result of human influences, two major shifts took place: a depletion of marine predators and an outburst of the alien comb jellyfish. Overfishing triggered both regime shifts, which resulted in system-wide upheaval in the marine food web.
A similar situation of overfishing and pollution has occurred in the Bohai Sea in China since the late 1980s. Together with the influence of the Yellow River cut-off, which is a shut-off valve to stop the water’s flow, the Bohai ecosystem experienced a dramatic change in community structure between the 1980s and the 1990s. This shift was not only over the geographical regions but also at both the species and family taxonomic levels.
For the sake of the world’s oceans and their importance to the global commons, wiser approaches than we now employ to the caretaking of our oceans and to controlling the sustainability of fisheries are vital. Even if better care is taken to repair the marine fisheries, a prolonged warming of the oceans will surely alter today’s options. For example, changes in the environmental features of China’s Yellow Sea during the last twenty-five years of the twentieth century included increases in the water temperature that are consistent with the recent global warming in northern China and the adjacent seas, such as the Bohai and the East China. The reduction of dissolved oxygen is probably attributable to the increase in temperature and the decrease in primary production in these regions. On the one hand, the increase in dissolved inorganic nitrogen is attributable mainly to precipitation and partly to the discharge of fresh water from the Chang Jiang (Yangtze) River basin. On the other hand, decreases in the concentration of phosphorus and silicon are due to their declining concentrations in seawater that flows to the Yellow Sea from the Bohai Sea. As a result, the ratio of nitrogen to phosphorus is greatly increased in the water of the Yellow Sea.
Moreover, some responses of the Yellow Sea ecosystems to changes in physical variables and chemical biogenic elements include strengthening nutrient limitation, decreasing chlorophyll a (the most common type of chlorophyll), succession of dominant phytoplankton species from diatoms to non-diatoms, as well as changes in fish-community structure and species diversity.1
INDIRECT EFFECTS OF OCEAN WARMING
In addition, both direct and indirect effects of climate change on prey species can have several indirect effects on marine mammals, such as changes in their distribution, abundance, and migratory patterns, as well as the structure of their communities, susceptibility to disease and contaminants, and reproductive success. Climate change can also affect marine mammals through competition, as they are forced to shift their geographic distributions and migratory patterns, which create novel contacts among the various species that heretofore, had no contact.
Here, an example from the Gulf of Alaska is apropos. In the early 1980s, the Gulf of Alaska rose by 2° Fahrenheit and severely altered the marine ecosystem. Orcas (also known as “killer whales,”) living near the Aleutians traditionally ate Stellar sea lions and seals, both rich in blubber and loaded with calories. However, the sea lions and seals soon disappeared, leaving just the sea otters, which caused the orcas to change their diet.
It took only four orcas less than a decade to kill and eat 115,000 sea otters. Once the otters vanished, the number of sea urchins skyrocketed. The sea urchins, in turn have eaten most of the massive 18-foot-tall kelp forests, formerly the otter’s habitat. In addition, rising ocean temperatures killed the plankton, which fed the copepods and krill, which in turn fed the shrimps and Alaska king crabs. Shrimps, crabs, capelin, and herring are gone. A once-brimming diversified ecosystem has today been reduced to sea urchins, cod, Pollack, and sharks. The speed in which these species have been lost has been likened to that of the great extinction of the dinosaurs. Such is the cascading effect of global warming, as it alters one ecosystem after another.2
HAVE YOU THOUGHT ABOUT THIS?
Connecticut’s nuclear power plant shut down one of two units on Sunday because seawater used to cool down the plant is too warm.
Unit 2 of Millstone Power Station has occasionally shut for maintenance or other issues, but in its 37-year history it has never gone down due to excessively warm water, spokesman Ken Holt said on Monday.
Water from Long Island Sound is used to cool key components of the plant and is discharged back into the sound. The water may not be warmer than 75 degrees and following the hottest July on record has been averaging 1.7 degrees above the limit, the Nuclear Regulatory Commission said.
The federal agency issued an “emergency license amendment” last week, allowing Millstone, a subsidiary of Dominion Resources Inc., to use an average temperature of several readings.
“It wasn’t enough to prevent us from shutting down,” Holt said.
. . .
In addition to the extreme heat last month, the mild winter didn’t help because it kept Long Island Sound water unusually mild, Holt said.
Neil Sheehan, a spokesman for the Nuclear Regulatory Commission, said Millstone can do little to correct the problem. Cooling millions of gallons of water before circulating it in the plant is not an option, he said.
“Just hope for a cooling,” he said.3
Is this a portent of things to come because we—especially in the United States—refuse to take responsibility for our self-centered decisions and act wisely for the benefit of all generations? If you think this question is irrelevant, consider:
A new law in North Carolina will ban the state from basing coastal policies on the latest scientific predictions of how much the sea level will rise, prompting environmentalists to accuse the state of disrespecting climate science.
The law has put the state in the spotlight for what critics have called nearsightedness and climate change denial [emphasis mine], but its proponents said the state needed to put a moratorium on predictions of sea level rise until scientific techniques improve.
The law was drafted in response to an estimate by the state’s Coastal Resources Commission (CRC) that the sea level will rise by 39 inches in the next century, prompting fears of costlier home insurance and accusations of anti-development alarmism among residents and developers in the state’s coastal Outer Banks region.
Democratic Gov. Bev Perdue had until Thursday to act on the bill known as House Bill 819, but she decided to let it become law by doing nothing.
The bill’s passage in June triggered nationwide scorn by those who argued that the state was deliberately blinding itself to the effects of climate change. In a segment on the “Colbert Report,” comedian Stephen Colbert mocked North Carolina lawmakers’ efforts as an attempt to outlaw science.
“If your science gives you a result you don’t like, pass a law saying the result is illegal. Problem solved,” he joked.
The law, which began as a routine regulation on development permits but quickly grew controversial after the sea-level provision was added, restricts all sea-level predictions used to guide state policies for the next four years to those based on “historical data.”
Tom Thompson, president of NC-20, a coastal development group and a key supporter of the law, said the science used to make the 39-inch prediction was flawed, and added that the resources commission failed to consider the economic consequences of preparing the coast for a one-meter rise in sea level, under which up to 2,000 square miles would be threatened.
A projection map showing land along the coast underwater would place the permits of many planned development projects in jeopardy. Numerous new flood zone areas would have to be drawn, new waste treatment plants would have to be built, and roads would have to be elevated. The endeavor would cost the state hundreds of millions of dollars, Thompson said.
“I don’t want to say they’re being dishonest, but they’re pulling data out of their hip pocket that ain’t working,” he said of the commission panel that issued the prediction, the middle in a range of three predictions.
Thompson, who denies global warming [emphasis mine], said the prediction was based on measurements at a point on the North Carolina coast that is unrepresentative of the rest of the coast.
But the costs Thompson decries as wasteful are to the law’s opponents a necessary pill the state must swallow if it is going to face up to the challenge of protecting the coast from the effects of climate change.
State Rep. Deborah Ross, a forceful critic of the bill, compared it to burying one’s “head in the sand.”
“I go to the doctor every year. If I’m not fine, I’d rather know now than in four years,” said Ross, a Democrat who represents inland Greensboro, N.C., but owns property on the coast. “This is like going to the doctor and saying you’re not going to get a test on a problem.”
Its supporters counter that the law does not force the state to close its eyes to reality, but rather to base policy on more than a single model that produced what they believe are extreme results.
Republican State Rep. Pat McElraft, who drafted the law, called the law a “breather” that allows the state to “step back” and continue studying sea -level rise for the next several years with the goal of achieving a more accurate prediction model.
“Most of the environmental side say we’re ignoring science, but the bill actually asks for more science,” she said. “We’re not ignoring science, we’re asking for the best science possible, the best extrapolation possible, looking at the historical data also. We just need to make sure that we’re getting the proper answers.”
As it thrust North Carolina into a national debate about climate politics, the bill became a lightning rod at home.
A spokeswoman for Gov. Perdue said her office received 3,400 emails opposing the bill in the first week after it passed the Republican-controlled state legislature.
According to the U.S. Geological Survey (USGS), sea level rise along the portion of the East Coast between North Carolina and Massachusetts is accelerating at three to four times the global rate. A USGS report published in the journal Nature Climate Change in June predicted that sea level along the coast of that region, which it called a “hotspot,” would rise up to 11.4 inches higher than the global average rise by the end of the 21st century.
The historical political clout wielded by North Carolina’s developers has led some critics of the law to accuse legislators backing it to promote those who line the pockets of their campaigns.
The largest industry contributors to McElraft’s campaigns have been real estate agents and developers, according to the National Institute on Money in State Politics. Her top contributor since she was elected to the General Assembly in 2007 has been the North Carolina Association of Realtors, followed by the North Carolina Home Builders’ Association.
McElraft, who is a former real estate agent and lives on Barrier Island off the coast, denied that campaign contributions ever influence her decisions as a lawmaker, and said her votes have not always favored increased development.
More than simply protecting developers, the new law protects homeowners from an overactive state government that would take away their right to build on their own property, McElraft said. Given an increased projected risk of flooding, insurance companies would likely charge coastal property owners, who already pay higher premiums, a concern Rep. Ross said she shared.
Ross, though, said she would rather pay for a more expensive insurance policy on her coastal home than be uncertain about whether it will be wiped out by the Atlantic Ocean in a few decades.
Gov. Perdue released a statement Thursday that gave a qualified endorsement of the law while urging lawmakers to develop a coherent approach to sea-level rise.
“North Carolina should not ignore science when making public policy decisions. House Bill 819 will become law because it allows local governments to use their own scientific studies to define rates of sea level change,” Perdue wrote.4
Check this out. Now,how would you choose?
Oceans In Crisis:
1. The preceding discussion of the ocean is based on: (1) Martin V. Angel. Biodiversity of the Pelagic Ocean. Conservation Biology 7 (1993):760–772; (2) I. Cacho, J. O. Grimalt, and M. Canals. Response of the Western Mediterranean Sea to Rapid Climatic Variability during the Last 50,000 Years: A Molecular Biomarker Approach. Journal of Marine Systems 33–34 (2002):253–272; (3) Nathaniel B. Weston and Samantha B. Joye. Temperature-Driven Decoupling of Key Phases of Organic Matter Degradation in Marine Sediments. Proceedings of the National Academy of Sciences 102 (2005):17036–17040; (4) C. Lin, X. Ning, J. Su, and others. Environmental Changes and the Responses of the Ecosystems of the Yellow Sea during 1976–2000. Journal of Marine Systems 55 (2005):223–234; (5) M. A. Tobor-Kapon, J. Bloem, P.F.A.M. Romkens, and P. C. de Ruiter. Functional Stability of Microbial Communities in Contaminated Soils near a Zinc Smelter (Budel, the Netherlands). Ecotoxicology 15 (2006):187–197; (6) Georgi M. Daskalov, Alexander N. Grishin, Sergei Rodionov, and Vesselina Mihneva. Trophic Cascades Triggered by Overfishing Reveal Possible Mechanisms of Ecosystem Regime Shifts. Proceedings of the National Academy of Sciences 104 (2007):10518–10523; (7) Z. V. Finkel, J. Sebbo, S. Feist-Burkhardt, and others. A Universal Driver of Macroevolutionary Change in the Size of Marine Phytoplankton over the Cenozoic. Proceedings of the National Academy of Sciences 104 (2007):20416–20420; (8) H. Zhou, Z. N. Zhang, X. S. Liu, and others. Changes in the Shelf Macrobenthic Community over Large Temporal and Spatial Scales in the Bohai Sea, China. Journal of Marine Systems 67(2007):312–321; (9) Moriaki Yasuhara, Thomas M. Cronin, Peter B. deMenocal, and others. Abrupt Climate Change and Collapse of Deep-Sea Ecosystems. Proceedings of the National Academy of Sciences 105 (2008):1556–1560; (10) James G. Mitchell, Hidekatsu Yamazaki, Laurent Seuront, and others. Phytoplankton Patch Patterns: Seascape Anatomy in a Turbulent Ocean. Journal of Marine Systems 69 (2008):247–253; (11) Roman Stocker, Justin R. Seymour, Azadeh Samadani, and others. Rapid Chemotactic Response Enables Marine Bacteria to Exploit Ephemeral Microscale Nutrient Patches. Proceedings of the National Academy of Sciences 105 (2008):4209–4214; and (12) Robert Ptacnik, Angelo G. Solimini, Tom Andersen, and others. Diversity Predicts Stability and Resource Use Efficiency in Natural Phytoplankton Communities. Proceedings of the National Academy of Sciences 105 (2008):5134–5138.
2. The preceding three paragraphs are based on: (1) Maria Cone. Aleutian Islands: A Wilderness Ecosystem in Collapse. Philadelphia Inquirer. January 28, 2001. http://www.commondreams.org/headlines01/0128-01.htm and (2) James A. Estes, E.M. Danner, D.F. Doak, and others. Complex Trophic Interactions in Kelp Forest Ecosystems. Bulletin of Marine Science, 74 (2004):621-638.
3. Stephen Singer. Warm Seawater Forces Conn. Nuclear Plant Shutdown. http://abcnews.go.com/US/wireStory/warm-seawater-forces-conn-nuclear-plant-shutdown-16994978#.UCk1jhwU64A (August 13, 2012).
4. Alon Harish. New Law in North Carolina Bans Latest Scientific Predictions of Sea-Level Rise. http://abcnews.go.com/US/north-carolina-bans-latest-science-rising-sea-level/story?id=16913782#.UBsGhBwU4pc
Text © by Chris Maser 2012. All rights reserved.