The Engineer's Notebook is a shared blog for entries that don't fit into a specific CR4 blog. Topics may range from grammar to physics and could be research or or an individual's thoughts - like you'd jot down in a well-used notebook.
Next month marks 100 years since the Jersey Shore shark attacks. A rogue shark (or multiple sharks, depending on which scientist you ask) killed four people and injured one during a two week span in early July 1916, at a time when a brutal heat wave and polio epidemic were driving thousands to resorts on the Atlantic coast. The attacks not only spurred panic and shark eradications on a national scale, they also immediately redefined the shark’s image from one of a timid sea creature to “the incarnation of ferocity.” Shark fever swept the nation, and soon newspaper cartoonists were using sharks to lampoon topics as diverse as German U-boats and prudish Victorian bathing suits.
Today, of course, ichthyologists know the truth about sharks and their behavior: they have lots of sharp teeth and occasionally attack without provocation. The popularity of films like Jaws and the annual sharkathon Shark Week, which kicks off June 25th this year, confirms that the mystique is still in vogue a century after the New Jersey incidents. While fatal shark attacks draw heavy media attention, they’re quite rare, with less than 100 total attacks reported each year. Still, those with a stake in beaches and resorts use a variety of technologies to prevent attacks.
A simple strategy for preventing attacks is to detect a shark’s presence and warn beachgoers to get the heck out of the water. In Cape Cod, Massachusetts, where a burgeoning seal population is drawing record numbers of great whites closer to shore, municipalities are posting traditional signage as well as large, dramatic billboards showing scary-looking sharks. For people whose heads are permanently looking down at their phones even at the beach, local group Atlantic Great White Conservancy is launching an app to allow visitors to track tagged great whites or quickly report seeing untagged ones. This year Cape Cod and other locales on the Eastern Seaboard may begin using drones to monitor shark populations close to shore. California and Australia already engage in drone monitoring, but the murky East Coast waters make visual sightings a challenge.
The other angle is to repel sharks from heavily populated beaches altogether. Traditionally, drum lines and shark nets were used for this purpose, but these methods endanger other non-harmful species, including non-aggressive sharks. South Africa’s KwaZulu Sharks Board is currently commercializing a shark-deterrent cable they tested in 2014. The cable features vertical “risers” that emit a low-frequency signal designed to confuse the shark’s sensory system. A shark’s nose contains an electroreceptive organ called the ampullae of Lorenzini that detects the potential difference between the voltage at the base of the electroreceptor and the voltage at the shark’s skin. The ampullae allow the shark to detect a far-off living creature’s heartbeat through the water, assisting with hunting and tracking. If successful the cable would be a huge improvement over shark nets: sharks have the greatest electrical sensitivity of any known animal, so the small electric fields won’t bother any other sea life or nearby humans. According to the Shark Board, the cable’s current is so small that a person accidentally contacting the cable would feel little more than a tingle.
Shark attacks are rare, but as evidenced by the recent Orlando alligator incident, most vacationers aren’t attuned to keeping their eyes peeled for local wildlife hazards. Development of sharkproof tech seems to benefit all involved, from the beachside communities who lose business at the first sign of a fin to the tourists who depend of them to stay safe.
Snorkeling along part of Bermuda's coral
reef was one of the highlights of my recent trip to the island. Given the dire
state of corals around the world, spending a little time amongst robustly
healthy corals, and the resident fish, was a pleasure and a privilege. Why is
Bermuda's reef in such good shape? Why are others, from the Great Barrier Reef
to locations in the Florida Keys, dying? What, if anything, can we do to save
what's left? Big questions, and articles abound that describe problems and
Rather than regurgitate a summary of the
plethora of virtual ink dedicated to coral, I'll look at one less-obvious
stressor of coral ecosystems. I'll also look at some ideas for coral
restoration and ways to prevent further damage.
Coral Bleaching: Symptom of Stress
This year's El Nino event sparked the
biggest coral die-off since 1998's El Nino. Pictures of swaths of bleached
Great Barrier reef coral - estimated at one-third of the entire reef - show up with dismaying frequency. A number of news outlets published stories
as I was writing this post. This phenomenon occurs when stressed corals expel
the algae, called zooxanthellae, that live symbiotically within coral tissues.
The algae are the coral animal's major food source, as well as the source of
its color. NOAA's infographic below demonstrates this process. Soft corals are particularly prone to bleaching.
Stressors: Obvious and Not-So-Obvious
Those of you who are reading this can
undoubtedly list some obvious anthropogenic environmental stressors.
Global warming and increased ocean
Changes in ocean water chemistry -
salinity levels and acidity
Pollution from waste runoff
Heat pollution from power plant cooling
Overexposure to humans via recreational
Overfishing and use of destructive
Loss of fish which clean seaweed from
An additional and more subtle culprit is
the chemicals in most sunscreens. The oldest research I found in a cursory web
search is an from Environmental Health Perspectives published in 2008, "Sunscreens Cause Coral Bleaching by
Promoting Viral Infections." The role of sunscreen hasn't gotten much attention until this latest episode of
massive bleach-outs, though. At the time of publication, the authors estimated
that 4,000 to 6,000 metric tons of sunscreen washes off swimmers in oceans
worldwide. The more swimmers and divers cluster around reefs, the higher the
concentration of washed-off Coppertone. And even a vanishingly small amount of
the bad stuff can wreak havoc. Ironic that the stuff that protects humans from
sunburn and skin damage helps cause coral to lose color and die.
The sunscreen chemicals that cause
damage are paraben, a preservative; cinnamate and a camphor derivative, UVB
blockers; and benzophenone, a UVA blocker. These chemicals do their dirty work
by causing dormant viruses in coral's symbiotic algae
to wake up and replicate,
eventually causing the algae to explode. The explosion propels the viruses into
surrounding seawater where they can infect other corals. There is also evidence
that chemicals alter the DNA of juvenile coral polyps, causing deformities and unviability.
Sunscreens with non-chemical UV blockers
don't harm coral - at least, as far as we know today. These non-chemical
blockers are our old friends zinc oxide, the stuff lifeguards paint on their
noses, and titanium dioxide. Together these provide broad spectrum protection.
A lot of websites advertise reef-safe and reef-friendly sunscreens and
An Aside about European Sunscreens
Recently I'd read that European and
Australian scientists have access to much more effective sunblocking chemicals that
are unavailable to those of us in the US. The story of why they are unavailable, despite 20 years' worth of user data
demonstrating their safety and effectiveness, is too long for this post.
Suffice it to say that testing takes money, either from the FDA or the product
manufacturer, and evidently no one's interested enough to pony up.
I wondered if these FDA-banned
ingredients are safer for coral than the three UV blockers listed above. I was
thinking hey, not only are US citizens unnecessarily deprived of more effective
sunscreens, we're also killing coral. Sure enough, as far as we know, none of
the ingredients listed below harm coral or humans, at least not European and
Australian humans. To add a touch of irony, a factory in South Carolina
manufactures sunscreen with banned ingredients and ships it all to Europe.
Tinosorb M (UVA blocker)
Mexoryl XL (UVA blocker; SX available in
the US but less effective)
Uvinul T 150
Uvinul A Plus
Coral Preservation and Growth
Stressed coral dies quickly and in large
quantities. However, coral reefs grow agonizingly slowly. Large corals, like
brain corals, grow 0.3 to 2 centimeters per year; soft corals, up to 10
centimeters a year. At this rate, a reef takes 10,000 years to form.
A large barrier reef or an atoll can take 100,000 to 30 million years to form. Given
this timeframe, preservation efforts are far more important than attempts to
create new reefs, although there are ongoing efforts to provide structures,
like sunken ships, for coral polyps to latch onto. Mr. Best in Show and I saw
coral starting to grow on a shipwreck on our snorkeling trip; Bermuda has
plenty of wrecked ships, most or all of which ran afoul of the reef.
Individuals can help keep coral healthy
by using the right sunscreen and by refraining from touching coral when snorkeling
or SCUBA-ing. Creating marine preserves where harmful activities are banned and
human access is regulated is mandatory. Bermuda's government has passed laws to
protect the island's reefs since the 1600s; this protection is one key factor
in Bermuda reef health. Each of the factors leading to reef death can be
addressed if enough political and ecological interest exist. For example,
restoring populations of reef-cleaning fish directly improves reef health.
Diligent monitoring programs, such as those managed by the Bermuda Reef Ecosystem Analysis and Monitoring (BREAM), discover potential threats and
can avert significant damage - at least, that's what we hope. Global warming and
carbon dioxide levels have already killed irreplaceable swaths of coral
world-wide; what the future holds, we can't know.
Are you a workaholic? Do you brag about it? Or are you
trying to stop?
A study of 16,426 working adults in Norway studied the
association between workaholism and psychiatric disorders, specifically ADHD,
OCD, anxiety, and depression. Image credit
The study defined seven criteria when identifying addictive
behavior. They are:
You think of how you can free up more time to
You spend much more time working than initially
You work in order to reduce feelings of guilt,
anxiety, helplessness or depression.
You have been told by others to cut down on work
without listening to them.
You become stressed if you are prohibited from
You deprioritize hobbies, leisure activities,
and/or exercise because of your work.
You work so much that it has negatively
influenced your health.
Participants scoring 4 (often) or 5 (always) on four or more
criteria identify a workaholic.
Researcher and clinical psychologist Specialist Cecilie
Schou Andreassen, at the University of Bergen (UiB), and visiting scholar at
the UCLA Semel Institute for Neuroscience and Human Behavior, said that
"workaholics scored higher on all the psychiatric symptoms than
32.7 per cent
met ADHD criteria (12.7 per cent among non-workaholics).
25.6 per cent OCD
criteria (8.7 per cent among non-workaholics).
33.8 per cent
met anxiety criteria (11.9 per cent among non-workaholics).
8.9 per cent met
depression criteria (2.6 per cent among non-workaholics).
People who work to the extreme may have deeper psychological or
emotional issues. But whether the disorder leads to workaholism, or workaholism
causes discorders it still unclear.
You're an island in the subtropical North Atlantic, with no
freshwater lakes or streams. Nothing but salt water all around you. How do you
provide fresh water for a population of 60,000 residents and more than 200,000
visitors a year? Your residents use technology that's nearly 400 years old.
This technology not only catches and stores rainwater, it also helps keep
buildings cool in hot weather and firmly on the ground during hurricanes.
Despite changes in materials of construction, the Bermuda Roof - required by
the island's building code -- graces the tops of houses all over Bermuda. The
design makes so much sense it's used in other countries as well.
The first English colonists arrived on Bermuda in 1609,
rather by accident. The Sea Venture, a ship taking passengers to the Jamestown
colony in Virginia, foundered on the surrounding coral reef during a hurricane.
The passengers elected to remain on the island even after completing a
replacement ship some months later. The lack of fresh water was readily
apparent; although some water filters through the island's coral surface to
underground lenses, the original settlers weren't prepared to locate and drill
for it. So the new residents started harvesting rainwater.
The ingenious method Bermudians devised to collect rainwater
is to create stepped roofs - hence, the ziggurat - that guide rainwater to a
slanted gutter. The gutter connects via pipes to an underground cistern or
holding tank, where water is stored until needed. Current building codes
require Bermudians to make at least 80 percent of a roof's square footage a
rainwater catchment area. With an average annual rainfall of 55 inches, that's
a lot of water to catch and save.
The rainwater-collection system incorporates more than just
the gutter-to-cistern path. Several critical components lead to this system's
success. These roofs, whether old or brand new, are nearly hurricane-proof; the
Bermuda building code requires that roofs weigh 66 pounds per square foot (that's
what the scuba boat pilot told Mr. Best in Show and me).
The original roofs were made of limestone "shingles," oblong slices of the
island's native limestone mortared down over a hip-roof frame made of Bermuda
cedar. The finished roof is then mortared over to fill in joints. Since the
island can no longer supply limestone and cedar, contemporary roof slates are
made of modern materials, such as expanded polystyrene (EPS), laid on a cement
Roof coating: Original
roofs sported bright-white coatings of lime - essentially whitewash. This
bright coating reflected the sun's glare, helping keep buildings cooler, and
helped sanitize the rainwater. Today's roofers use white elastomeric paint.
Although this material lasts longer than whitewash, homeowners still have to
repaint every two or three years. This coating, like whitewash, helps prevent
mildew and mold.
Gutters: Unlike conventional roof gutters, Bermuda
roof gutters run slantwise across the slates, starting about two-thirds of the
way down the roof, carrying rainwater through a pipe to the underground storage
cistern. The gutters themselves are fashioned from cement.
passes through a filtration system as it funnels into below-ground cisterns. The
cistern stores water, pumping it into a pressurized tank for distribution
through the plumbing system.
Homeowners have to clean their roofs periodically to remove bird droppings and
other foreign materials. As mentioned above, roof coatings last two or three
years, necessitating re-coating at regular intervals. Public health experts
recommend regular tank cleaning to ensure potable water.
Side benefits of the Bermuda Roof
A white-painted roof reflects sunlight back into the
atmosphere, helping to keep the building it shelters cool. Something I didn't
know is that, according to Lawrence Berkeley National Laboratory 1000 square feet of white roof has the equivalent effect of cutting 10 tons
of carbon dioxide emissions. Multiply that by all of the white roofs in
Bermuda, and the CO2 equivalent reduction is noticeable.
As mentioned above, the heavy roof prevents Bermudian homes
from becoming airborne during hurricanes. The roof shingles, much less the
entire roof, don't blow
off in high winds. Thanks to the mortar and roof
sealant, these roofs are watertight, as well.
Aesthetically, the consistent use of this style of roof,
coupled with the pastel paint used on Bermuda buildings large and small,
contribute greatly to the charm of this British Overseas Territory. Bermudian
indigenous architecture is considered by some to be the island's greatest
Recent studies indicate that general cistern water quality
isn't necessarily as good as one expects from a traditional municipal water
supply or private well. Two years ago, a Canadian public health specialist from
Universite´ Laval in Quebec alarmed Bermudians when he claimed that cistern
water contains too much fecal matter to be safe to drink. Dr. Eric Dewailly
based his statement on research completed in 2013. He proposed that bird
droppings are the most likely source of fecal-matter bacteria, highlighting the
need to clean roofs regularly. Dr. Dewailly encouraged residents to incorporate
an ultraviolet treatment system to kill bacteria.
A study of the mineral composition of cistern water produced
more equivocal results. Sediments that accumulate in cisterns can contain
elevated levels of nasty stuff like arsenic, but the levels vary from tank to
tank. The authors called for more research to clarify the picture.
I was researching my previous post, on living walls, I discovered that an inorganic substance, stone wool, is
used as a growing substrate for some wall systems. Stone wool? I'd never heard
of such a thing. The more I looked into this topic, the more interesting
substrates I found. These all represent advances in the horticultural use of
existing materials, some of them organic like coconut coir, some, like rock
wool, inorganic. Improvements in substrate materials have no doubt contributed
to the increase in living walls; the same improvements are a boon to
horticulture in general.
What's a substrate?
Simply put, a horticultural substrate is a substance in
which a plant's roots grow. Garden soil is a substrate. Vermiculite is a
substrate. Plants do not need potting soil, or even organic matter, for growth.
They do need something that holds roots firmly enough to enable the plant to
grow up and that allows water and nutrients to reach the roots.
Why look for different substrates?
In the 1960s, a couple of factors impelled the commercial
horticulture industry to seek out new types of plant growth substrates. The
growing environmental movement awakened concerns about increasingly intensive
use of farmland, which exhausts the land. These concerns led, among other
actions, to the banning of methyl bromide, a soil disinfectant commonly used to
prepare soil for planting. Finding new
methods for crop culture would take pressure off of existing resources.
I'd never heard of stone wool, and I was baffled that
something made out of basalt would be an acceptable plant substrate. Although
mineral wool insulation has been around for a long time, a mistake - a bad
batch of insulation - led to its use as a plant growth substrate. A Danish
insulation manufacturer, the ROCKWOOL group, tossed the defective stone wool
out on factory property. Lo and behold, sometime later staff noted that small
plants were growing in the insulation batts.
The company worked with university researchers
to perfect this stone wool for
the 1990s, coir's advantages as a horticultural substrate attracted commercial
growers, and it's popular today, particularly for hydroponics and mushroom
cultivation. At least one company sandwiches coir mats into panels for vertical
gardening. In addition to sheets and loose chopped fibers, horticultural-use
coir is formed into bricks and cubes.
Coir offers several advantages as a growth substrate, not
least of which is the attractive natural tan-to-brown color of coir sheets and
bricks. Other advantages include that
Coir can hold up to five times its weight in water and
release it slowly, yet it drains well and prevents water pooling and rot.
Coir is very slightly acidic, with good pH for plant growth.
Roots move easily into the pores between coir fibers.
Depending on its origin, coir can contain usable amounts of
plant nutrients, such as phosphorus.
Patrick Blanc, the genius behind contemporary vertical
gardens, started out using synthetic felt, irrigating plants with
nutrient-laden water. Fast-forward to
the 21st century for the introduction of an improved type of felt
for vertical gardening. This new felt is made from 100 percent recycled plastic
bottles, so it's environmentally friendly and durable.
At least two companies market pockets made from
recycled-plastic felt, with two slightly-different pocket designs and
configurations. Both designs make use of the felt's capacity to wick water
throughout the pocket. Both designs also incorporate at least a minimum amount
of another growth substrate, typically a soil-less mixture. Plant roots can
penetrate the felt.
These pockets make small-scale vertical gardening easy,
indoors or outside. They can be hung on drywall without causing water
damage, and gardeners can swap out and rearrange plants easily. Home gardeners
that lack access to a plot of ground can use these pouches to grow vegetables and herbs -
perhaps not squashes, but definitely lettuce and other smallish plants -- indoors or on a deck or patio.