The Caspian Sea

A remnant of the Paratethys Sea, the Caspian Sea is the largest inland body of water on Earth. Covering more than 143,000 square miles, it was cut off from the Black Sea when the Caucasus Mountains rose some 6 million years ago, a product of the Red Sea opening which forced (and continues to force) the Arabian Plate to collide with the Eurasian Plate. Retaining some salinity from the Paratethys, the Caspian Sea has become a massive basin lake, receiving inflow from more than 130 freshwater rivers but having no outlet to the sea; 80% of the inflow is via the Volga River while the combined flow of the Ural and Kura Rivers adds another 15%.

Since this inflow is primarily from the north and northwest shores of the Caspian Sea, its relatively shallow northern waters (only 20 feet deep) are fresh while the deeper waters of its southern section (exceeding 3000 feet in some areas) have a salinity that is 1/3 of that found in our oceans. Kara-Bogaz-Gol, a large lagoon on its eastern shore (within Turkmenistan) has been nearly cutoff by sandbars and receives inflow only during periods of high water in the Caspian Sea; the lagoon's waters, subject to intense evaporation, have a salinity that is 10 times that of sea water. Today, five countries border the Caspian Sea: Russia on the northwest, Kazakhstan on the northeast, Azerbaijan on the southwest, Turkmenistan on the southeast and Iran on the south; except for the Caspian Depression to its north, the Caspian Sea is rimmed by highlands and its surface elevation, while variable, is about 92 feet below sea level.

While lush wetlands are spaced along its western and southern shores, the Caspian Sea is bordered by desert on its northern and eastern coasts; of special interest is a region of geothermal mud domes along part of the Azerbaijan coast, a testament to plate subduction in that area. Famous for a magnificent diversity of birdlife (especially during migrations), its prized sturgeon caviar and its endemic Caspian seals (thought to have arrived when the Paratethys connected to the North Sea), this unique and varied ecosystem is threatened by both global warming and industrial pollution (especially from oil and gas production). Since it is rimmed by five countries, the effort to protect this ecological treasure is especially challenging.

Madagascar's Cyclone Season

Madagascar, the fourth largest island on Earth, lies off the southeast coast of Africa, in the western Indian Ocean. Oriented northeast to southwest, the island is bathed by southeasterly trade winds throughout the year, producing copious precipitation along its eastern coast; indeed, some areas receive up to 150 inches of rain. Since highlands run down the center of the island, the western coast of Madagascar lies in their rain shadow and its climate is much drier.

The wet season in Madagascar runs from November through April, encompassing the warmest months of the year. During the Southern Hemisphere summer, the Intertropical Convergence Zone (ITCZ) drifts south from the Equator and, from December through early March, it crosses the northern half of Madagascar. Along this zone, northeasterly and southeasterly trade winds merge, producing lift and bands of thunderstorms; the colliding winds also produce wind shear at the surface and, if upper level winds are calm, cyclones may develop. Most common from January into March, those that strike Madagascar develop east of the island, over the warm waters of the Indian Ocean, and then drift westward along the ITCZ.

This week, Cyclone Giovanna, a category 4 storm, packing winds up to 120 miles per hour, has produced devastation across the island nation, killing at least 5 persons. After crossing Madagascar, it is expected to impact Mozambique, on the African mainland.

A Free Dolphin Show

Never a fan of Disney-esque human-wildlife bonding films and personally concerned about the new wave of ecotourism that baits wild creatures for close human encounters, I favor granting our wild neighbors their space, satisfied to observe them at a safe and non-threatening distance. But yesterday afternoon, as I sat on our seawall along Sarasota Bay, a dolphin chose to pay a visit.

Racing along the wall, he repeatedly turned his head to glance at me as he chased a school of fish. Catching one in his mouth, he tossed it into the air several times before ingesting the meal. At one point, he stretched out on the surface, looked in my direction and then sped toward the wall, performing a flip turn just before impact. The show continued for about ten minutes before he tired of the performance and swam off to the south. I have no doubt that his antics were a means of communication, perhaps an attempt to encourage my participation.

Most of all, this delightful experience reinforced my conviction that whales and dolphins are too intelligent to be held in captivity. No amount of tasty fish or audience appreciation can justify their loss of freedom.

Comb Jellies

On our regular trips to Longboat Key, Florida, we encounter a spectacular diversity of wildlife, including dolphins, manatees, stingrays, ghost crabs and a wide variety of coastal birds. But yesterday afternoon, while sitting on a seawall along Sarasota Bay, I observed a flotilla of comb jellies for the first time. Drifting in the calm bay waters, they looked like miniature Goodyear Blimps, complete with neon messages, flashing along their transparent hides.

Members of the phyllum Ctenophora, these marine invertebrates consist of an ovoid mass of gelatinous tissue, enveloped in a thin ectoderm and pierced from front to back by a primitive gastrointestinal tract. On its outer surface are eight lines of cilia, which beat in a coordinated fashion to propel the jelly through the seawater; nevertheless, most of their movement is subject to currents and tides. Carnivores, comb jellies are devoid of stinging tentacles but are ravenous in their consumption of microscopic plankton. Like many other marine invertebrates, these jellyfish are hermaphrodites, producing both eggs and sperm; fertilization usually occurs in the open water but, in some species, takes place within the gut and the offspring are not released until their early development has begun.

My research turned up some disagreement on the source of the iridescent green and orange that flashed along their otherwise transparent bodies. Some attribute these bright colors to sunlight refraction by the beating cilia while others mention the presence of bioluminescence, originating in gastrovascular tubes beneath the lines of cilia. Based on my personal observations, I would favor the latter since the linear displays occurred in shaded waters, adjacent to the seawall. Whatever the source of their colorful light shows, the chance observation of these fascinating creatures was a unique and rewarding experience.

The Largest Fish on Earth

Compared to its marine cousins, the whale shark, the largest fish on Earth, is a relative newcomer to the ocean ecosystems of our planet. While ancestral sharks and boney fish appeared in the Devonian Period, some 375 million years ago (MYA) and modern sharks arose in the Jurassic (160 MYA), current fossil evidence suggests that whale sharks did not evolve until the early Tertiary Period, about 60 MYA; ironically, this was the same time that their unrelated namesake, the mammalian whales, where returning to the sea.

Solitary for much of the year and known for their long migrations, whale sharks favor tropical and subtropical seas where they filter-feed near the surface, scooping in plankton, krill, small squid and small fish with their wide mouths. They do congregate at certain feeding grounds during specific times of the year, drawn by the seasonal spawning of coral or by plankton blooms; perhaps the most famous whale shark rendevous is at the Ningaloo Reef, off the west coast of Austalia.

Often exceeding 40 feet in length and weighing over 20 tons, whale sharks live for 70 years or more (perhaps as much as 120 years). Females give birth to hundreds of live young, each about 2 feet long; those that survive predation by other sharks and large fish will be sexually mature by the age of thirty. Despite bans, adult whale sharks are hunted by various human cultures, especially in Southeast Asia. Since they move slowly and feed near the surface, they are also prone to injury from motorized boats and, like many other marine species, have become the target of eco-tourism.

Tropical Storm Dynamics

The development of a tropical storm is dependent upon three factors: warm ocean waters, hot, humid air at the surface and light upper-level winds. For these reasons, early season Atlantic hurricanes usually develop in the relatively shallow waters of the Gulf of Mexico, across the Caribbean and along the Southeast Coast of the U.S. While tropical waves begin to move westward, out of Africa, in early summer, they encounter cool waters in the central Atlantic and tropical storms do not usually develop; by August, the ocean temperature has increased and the peak of the Atlantic hurricane season begins, continuing through September and into early October.

Once a tropical storm develops, favorable conditions, discussed above, may cause it to strengthen into a hurricane. Conversely, if the storm moves into cooler waters, makes landfall or encounters strong upper level winds, the storm dynamics break down and the system weakens or dissipates. In some cases, favorable conditions may be re-encountered and the storm may redevelop; this occasionally occurs in Central America, when Gulf of Mexico storms weaken over land and then re-blossom in the eastern Pacific.

Global warming may extend the hurricane season by producing warm ocean waters earlier in the summer and later in the fall. Then again, climate change might alter upper level wind patterns, shifting the zone of tropical storm development and impact. Time will tell.

Illusion in the Gulf

One year after the Deep Water Horizon exploded in the Gulf of Mexico, all appears to be well. The blue waters and white beaches are no longer tainted with black swaths of oil, sea birds are not encased in crude and most of the Gulf fisheries have reopened for business. BP and the Federal Government have pulled most of their cleanup crews, fines have been levied and reimbursement funds are trickling through the Gulf Coast economy. Most important to U.S. oil companies, offshore drilling continues in the wake of our country's greatest environmental disaster.

As often occurs after such events, political and industrial response is directly proportional to the degree of media coverage that is generated by the disaster. Once the gushing oil well was plugged, almost three months after the explosion, intense media coverage waned and the commitment of BP faded with the camera lights. The Federal Government, hobbled by debt and a weak economy, lost interest in the Gulf and failed to prosecute the other industrial giants responsible for this catastrophe.

The fact that we continue to refer to the event as an "oil spill," as if an oil barge capsized in the Gulf, highlights our tendency to minimize the effects of man-made disasters; in this case, crude oil gushed into the Gulf for 87 days and it's hard to accept the soothing conclusion that environmental effects have been limited. We have yet to learn how deep water ecosystems were affected by the oil and, as any student of nature knows, all ecosystems are interconnected. The image of recovery, fostered by the oil industry and condoned by our Government, is but an illusion.

Ocean Sunsets

Sunset, whether unfolding behind a range of mountains, amidst the painted skies of the Great Plains or beyond the jagged silhouette of a modern city, is always a beautiful and stirring event. Ocean sunsets, however, seem to produce more emotional impact, as our glowing, orange star drops below the edge of the Earth.

Often witnessed by crowds of humans, whether on beaches, on a ship or on shoreline balconies, ocean sunsets are usually a collective experience, igniting a sense of wonder but dredging up a deep-seated fear, buried in the soul of man. Long before we came to understand the motion of heavenly bodies and the astronomical cause for sunsets, the gathering darkness, frought with a host of natural dangers, was surely a source of concern; whether the sun would return, bringing its life-sustaining heat and light, was not taken for granted.

Even today, as the sun drops behind the sharp line of the sea, this fear, however weak, wells up from our genetic past. While we might not acknowledge its presence, it surely plays a role in our emotional response to sunsets. Natural beauty, after all, comes with a price and our personal capacity to ward off the darkness is but a transient gift.

Ocean Currents & Regional Climates

The surface currents of our oceans, which extend to depths of 1500 feet, are determined by wind patterns and the effect of Earth's rotation. In the Northern Hemisphere, the primary oceanic currents flow in a clockwise direction while, in the Southern Hemisphere, they move counterclockwise. Those moving from the Tropics toward the Poles are warm currents and those moving from the Poles toward the Equator are cold currents.

More that a mixing of oceanic waters, these currents have a significant impact on the climate of coastal land areas. The Gulf Stream, for example, carries warm water from the Gulf of Mexico and Caribbean toward the North Atlantic, significantly moderating the climate in Iceland and the British Isles; in like manner, the Japan Current, flowing from Southeast Asia to Alaska, warms the climate of coastal Alaska and British Columbia. Cold currents, such as the Humboldt Current along the west coast of South America, the Benguela Current along the southwest coast of Africa, the California Current along the west coast of North America and the West Australian Current have a cooling effect on these coastal areas and support rich fisheries.

At the Equator, the currents merge into a westward flow while, around the coast of Antarctic, the surface current flows to the east; from these feeder currents, the circling oceanic currents arise. In the Atlantic, the Gulf Stream and Brazil Current carry warm water away from the Equator while the Canaries and Benguela Currents return cooled water from subpolar areas to the Equator. The Indian Ocean surface currents run north along western Australia, west along the coast of India, south along the east coast of Africa and east along Antarctica. In the Pacific, the California and Humboldt Currents, arising in subpolar regions, feed the westward equatorial flow which, at the west edge of the Pacific basin, splits into the warm Japan and East Australian Currents. The climate of any given coastal area is thus a function of both its latitude and the temperature of ocean waters that bathe its shores; of course, the direction of prevailing winds and the presence or absence of nearby mountains will also affect regional weather patterns.

Japan's Quake & Tsunami

Northern Japan lies on a southward projection of the North American Plate and, off its east coast, the Pacific Plate is subducting beneath it; friction along this subduction zone pulls down the edge of the North American Plate and, eventually, the Plate rebounds, triggering an earthquake and lifting the overlying ocean.

Today's massive quake, the most powerful in Japan's recorded history, measured 8.9 on the Richter scale and sent a wall of water across the northeast coast of that island nation. While most destructive close to the earthquake, the tsunami will propagate in all directions, affecting islands and coastlines along and across the Pacific. The axis of maximum energy is projected to pass through Hawaii and toward South America but tsunami warnings have been posted from Alaska to New Zealand, including much of the U.S. West Coast.

Widespread destruction and numerous deaths will surely be reported in Japan and the effects of this powerful earthquake will no doubt produce emotional, physical and economic damage across the globe. In this respect, the tsunami will spread well beyond the Pacific Basin.

La Nina & the Australian Floods

The massive flooding across eastern Australia, which began in November, has been associated with the La Nina phenomenon, which tends to peak every 3 to 7 years. Produced by high pressure over the eastern Pacific and low pressure over the western Pacific, this weather pattern results in strong Pacific trade winds, which bring relatively warm ocean waters to the southeast coast of Asia and the northeast coast of Australia. This spawns strong cyclones and excessive rainfall in these areas, generally during an autumn to autumn cycle in the Southern Hemisphere.

Coinciding with a high Southern Oscillation Index, which measures the seasonal variance of sea surface pressure between Tahiti and Darwin, La Nina episodes trigger excessive precipitation across northern and eastern Australia. This year's flooding has been especially severe, disrupting transportation, stranding inland towns, inundating coal mines and wiping out much of the region's wheat crop. The Great Barrier Reef may also be affected, as plumes from the rivers of northeast Australia sweep particulates and pollutants toward that fragile ecosystem.

The current Australian flooding may prove to be the worst in recorded history. Unfortunately, some climatologists project that the La Nina and the opposite El Nino patterns will intensify with the advance of global warming. For eastern Australia, that could mean an alternating pattern of severe floods and prolonged drought.

The Great Oceanic Plates

When Earth's Continents merged into Pangea, some 250 million years ago, the vast intervening ocean stretched across two oceanic plates, the Pacific and the Farallon; spreading out from a mid-oceanic ridge, the Pacific Plate lied beneath the western half of the sea while the Farallon occupied the eastern half, abutting the future Americas.

Pangea began to break up during the Triassic, as the Tethys Sea opened from east to west. Later, in the Jurassic, the Atlantic began to open, shoving the American Plates to the west. As this occurred (and continues to occur), the Farallon Plate was forced to subduct beneath the American Plates and, in doing so, added a cargo of sub-continents to western North America, crumpled up the Rockies and created a broken chain of subduction volcanoes from the Andes to southeast Alaska. Today, only remnants of the Farallon persist, including the Nazca Plate along the west coast of South America, the Cocos Plate west of Central America and the Juan de Fuca Plate (and a few smaller remnant plates) off the west coast of the Pacific Northwest.

The Pacific Plate, devoid of major continental masses continues to form along its ridge with the remnants of the Farallon and along its younger ridge with the Antarctic Plate. Inching to the northwest, the Pacific Plate scrapes through Southern California along the San Andreas Fault and eventually subducts beneath or overruns the North American, Eurasian, Philippine and Australian Plates in a broad arc, from the Aleutians to New Zealand. For now, only hotspot volcanic islands disrupt its vast expanse of open sea; eventually, this great oceanic plate will also disappear as new oceans open, our current continents rift apart and the Pacific subducts into history. Just like the Farallon and its many other predecessors, the Pacific Plate is a transient feature of Planet Earth.