marinememoirs-blog

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🌀 S W I P E 🌀 Check out my latest posts on plastic pollution, reef safe sun screen, physiology of diving and our dear creature of the week featuring the Pygmy seahorse and beautiful images provided by (at Utila, Islas De La Bahia, Honduras)

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Organism of the Week: Bargibant's Pygmy Seahorse

Pygmy seahorses were discovered by accident in New Caledonia on a on a gorgonian coral. There are currently seven known species (five named species) of these miniature syngnathids with more expected to be discovered. 

There are two key differences between seahorses and pygmy seahorses.

Pygmy seahorses have one gill opening on the back of their heads as opposed to two on their neck

Males brood their young in a pouch on their trunk rather than on the tail

Bargibant's Pygmy Seahorse is an extreme habitat specialists living exclusively on on gorgonian of the genus Muricella spp.   In particular the red-polyp Muricella plectana and will spend their entire adult life on a single gorgonian feeding off small crustaceans. As they are camouflaged to match the host species of gorgonian coral so well this gives them a higher chance of survival than most species of seahorse.

 Sources Kuiter, R. (2010). Seahorses, and their relatives. Chorleywood, UK: TMC Pub.

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Physiological effects of scuba diving and high atmospheric pressure.

Scuba diving

SCUBA diving is possible by the use of a self contained breathing apparatus using air consisting of 21% oxygen and 78% nitrogen. The use of scuba enables divers to swim at great depths and for long periods of time, which is not possible through aquatic activities such as normal swimming or snorkeling.

At sea level the barometric pressure of 760mmg is the equivalent of 1atm (atmospheric pressure). Scuba diving exposes the body to higher atmospheric pressure than usual and at a depth of 10 meters' of sea water the pressure is already 2atm, double that of sea level. The recreational limit for scuba diving is 40m where the pressure is already four times that of the surface however, many tech divers dive to much deeper depths.

Despite being an extremely enjoyable activity such pressures can cause physiological effects on the body with the two systems most affected by high atmospheric pressure being the cardiac and respiratory systems of the body. 

Air is inspired down into the trachea into the two bronchi which divide more so into the five lobes of the lung (three on the right, two on the left) until it passes into the bronchioles which have small air filled sacs called alveoli. These alveoli have an incredibly large surface area to enable for fast diffusion of O2 into the capillaries (which are one cell thick) from deoxygenated blood from the body and the fast diffusion of CO2 back into the alveolar sacs. The tidal volume of air breathed is approximately 500 mL, with ventilation into the lungs being made possible by pressure differences.

During inspiration contractions of the intercostal muscles and diaphragm enlarges the chest cavity resulting in an increase of alveolar volume leading to a decrease in alveolar pressure. This decrease in pressure gives way to air movement into the lungs which equalizes the pressure. Air leaves and is pushed out the lungs due to the relaxation of the prior contracted muscles. This is the elastic recoil.

The cardiovascular or circulatory systems carry blood from the heart round the body and back to the heart. This transport of blood round the body allows for the exchange of gasses, nutrients and waste products (e.g CO2) in the body blood and blood vessels.  Pulmonary circulation oxygenates the blood in the lungs before it is transported back to the heart to be pumped round the body. It is important for the cardiovascular to to regulate blood pressure regulation and blood levels to tissue to maintain homeostasis.  To help understand the effects of diving and high atmospheric pressure on the body it is important to understand the gas laws.

Pascal’s principle equates that any change in pressure in an enclosed fluid is equally is transmitted equally throughout that fluid, thus enabling our bodies to withstand the ambient pressure of the surrounding media. Most space in the body is made from water and therefore incompressible. It is only air filled spaces that are effected by pressure changes. Boyles law states that pressure and volume are inversely proportional at a given temperature, as pressure increases volume decreases, at 30m the volume of gas is 1/3 that at sea level.  Linking to Daltons law by which as the pressure increases as does the partial pressure of the constituent gas and as the partial pressure increases as does the amount dissolved into the tissues of the body accounted for by Henry’s law.

Hyperbaric conditions

Scuba diving exposes divers to hyperbaric conditions, in such condition there are many variable changes to that of sea level or 1atm.  When submerged there is a higher ambient pressure, divers as a result are exposed to and increase respired gas density, increased partial pressures and experience increased work while breathing. Notably there is also increased dead space (when using a breathing apparatus this refers to the space in the breathing apparatus by which the gasses must flow through as ventilation occurs) due to the regulator and hose. Even immersion in water up to the neck can begin to cause physiological changes activating the sympathetic nervous system and the parasympathetic nervous system through the diving reflex – a cardiovascular-respiratory response to immersion by the cardiovascular and pulmonary system.

This increase redistribution of blood helps to maintain blood pressure minimizing the effects of a lower heart rate. Heart rate variability (HRV) is the cyclic variations of heart rate created by the autonomic nervous system. It has been found that HRV increases during scuba diving and it is likely that this change in HRV is due to the haemodynamic changes involved in submersion. 

Exchange of oxygen by the lung is not impaired significantly by scuba diving especially up to the recreational limit. In many cases most of the pulmonary related effects of diving are related to to the immersion related increase of pulmonary blood volume, increase of dissolved gas and higher levels of inspired PO2 altering gas exchange functionality. Divers may experience and increase of dead space as the regulator hose decreases alveolar ventilation. The use of a demand valve regulator or a full face rebreathe mask reduces dead space as the diver does not have to breath in and out of the same hose pipe reducing the amount of CO2 in the chamber, such is the case with snorkeling. If ventilation is insufficient it can lead to hypercapnia due to elevated levels of CO2. To compensate for this respiratory rate or tidal volume must be increased. Compliance measures the ease by which the lungs and thorax expand. At depths there is an increase resistive and elastic loads, meaning greater effort is required for inhalation and exhalation due to the increased density of breathable gas. This decrease in lung compliance increases the amount energy necessary for breathing to occur.  Much of this is related to the increase in the gas density of air from scuba tanks largely because dense air has increased flow resistance with this resistance increasing with depth.

Expiratory reserve volume (ERV) relates to the amount of air that can be expired forcefully after expiration of tidal volume. Diving causes a decrease in ERV at shallower depths however with increasing depth there is an increase of ERV likely attributed to a bodily attempt to increase airway diameter and counteract increased airway resistance of dense breathable air.

Decompression sickness is attributed to ascent in diving. When at depth nitrogen is absorbed into tissues at the same pressure of the surroundings, problems occur when the dissolved inert gas nitrogen increases in size and moved out of the dissolved state and into the tissues forming bubbles which especially effect cavities in the body and can stretch or block blood vessels causing oxygen depravation. This condition can be avoided however if divers make necessary safety stops upon ascent. It is also important to breathe to enable an equilibrium of volume and ambient pressure of the surroundings. If divers ascend with a closed glottis it may cause lungs to burst. Arterial gas embolisms (AGE) may occur if gas bubbles block the transport of blood to the heart. AGE’s are likely to occur due to the pressure decrease of assent as the gas bubbles increase in size. If these bubbles are in the circulatory system, then can travel through he body and lead to brain embolisms.

The respiratory and cardiac systems have great abilities to withstand the increased pressures involved with diving as long as necessary precautions are taken place. The cardiorespiratory systems functions at almost normal capacity with the aid of SCUBA with most of the diver’s physiological effects in this system resulting from the increased work of having to breathe gas at a higher density than usual and increased air way resistance. At great depths > 40m it is commonplace to use alternative gas mix’s which make it easier for respiration during diving and also avoid negative effects of breathing ‘normal air’ at depth such as oxygen narcosis. Such deep dives would not be possible without alternate air mix’s and much greater physiological problems would occur. With a combination of natural body mechanisms and technological equipment it is possible to keep the physiological effects of hyperbaric conditions to a minimum.

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Sunscreen: a threat to coral reefs

Studies on coral reefs have found the chemicals found in sunscreens worn by beach goers, snorkelers and divers are having adverse effects on the health of coral reefs. In some areas thousands of visitors enter the sea day, causing dozens of chemicals to leech off skin and into our waterways.

The Federal Drug Administration (FDA) currently approves 17 sun blocks. Of these two are are physical blocks in which the suns rays are reflected and bounce away from the skin (titanium oxide and zinc oxide), the rest are chemical blocks which absorb the energy of UV radiation before it affects or damages your skin. Such chemical blocks include Avabenzon, Benzophenones, Cinnamates and Salicylates. Studies on the benzophenone Oxybenzone have shown that it is an extremely harmful chemical for coral reefs acting as an endocrine disruptor and genotoxin damaging coral DNA and altering how these organisms grow.

The UV absorbing compound also contributes to rapid and complete bleaching of hard corals, even at extremely low concentrations which in turn leads to substantial algal growth promoting phase shifts. Craig Downs, Ph.D, is one of the leading researchers on Oxybenzone at the Haereticus Environmental Laboratory in Virginia. His studies concluded that concentrations as low as 62 parts per trillion can cause vast amounts of damage... In Honolua Bay on Maui, oxybenzone levels were detected to be nearly 2,000 parts per trillion.

Notably the skin is the largest organ in the body  with many products being being absorbed into the body. Studies show that from urine samples taken from the US population 96% contained Oxybenzone, meaning the chemical  has almost almost-universal prevalence in the population. Oxybenzone enters the waterways through drainage systems and can pollute lakes, rivers and land and sea. 

Efforts to reduce pollution from oxybenzone can help protect corals from additional global anthropogenic stressors (rising sea surface temperatures, acidification, pollution). Local businesses and the service industry including eco tourism and dive shops are doing more to protect the local environment, especially those that rely on coral reefs. Notably Hawaii parts of Mexico are taking measures to ban products with oxybenzone and hopefully more places will follow suit.  Not only is it important to have reef safe sunscreen to protect our favorite environment it's important that other products such as shampoo and conditioner is reef safe.  Purchasing oxybenzone free sun screen and using reducing sunscreen usage (wearing long sleeved clothing and rash guards) is crucial.

EWG.org has a comprehensive list of safe sunscreens making it easier for consumers to make an informed choice on which products to buy including Stream2sea, Badger,Green People and Tropical Seas.

   Further reading: Marine Safe,  Haereticus Lab

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Plastic Pollution Pt.1

Plastic is a material we have begun to rely on heavily and use in place of many materials such as paper, metal, wood and glass. Plastic pollution is causing vast amounts of damage to marine environments and as the effects of plastic pollution draws more attention from scientists, public and the media many governments are finally begging to  implement laws to combat plastic based waste. Throughout this four part blog series we'll delve into the effects plastic is having on our planet and what we can do to help.

Modern day plastics began with Bakelite, the first fully synthetic polymer. It was lightweight, durable and could be moulded into an infinite amour of items. A 1924 article in Time magazine predicted that Bakelite was "material of a thousand uses". After this many types of synthetic polymers were developed however it was not until World War II when many natural materials became scarce that synthetic materials mass produced.

We now have many varieties of synthetic polymers which include polyethylene (used in plastic bags); polystyrene (used to make Styrofoam cups); polypropylene (used for fibers and bottles); polyvinyl chloride (used for food wrap, bottles, and drain pipe); and polytetrafluoroethylene, or Teflon (used for nonstick surfaces).

An Age of Plastic

Plastics are strong, lightweight and inexpensive which enables us to use them as a disposable commodity. In India 42% of the Countries plastic is used for packaging and Around one third of the words plastics are created for packaging alone.  Plastic has saturated the packaging sector for example: Planters® stated that there was “84% less packaging than glass jar by weight!” when the company replaced its glass jar for dry roasted peanuts with a recyclable plastic jar.  The company claimed that the switch would result in a 25% reduction in trucks on the road to ship the same amount of nuts, along with saving millions of pounds in packaging and shipping materials. For these companies using more material typically translates into higher environmental costs. Unfortunately these companies bare little responsibility for the environmental impact once the product has been sold to the consumer.

Once plastic's often single use need is complete, we allow 13 million metric tons of the material find its way into the oceans each year. In the ocean larger plastic debris that degrades into smaller and smaller pieces called micro plastics (less than five millimeters in length) with UV and wave  action accelerating this process. Many organisms mistake micro plastics for plankton and krill and eat them as food. Estimates suggest that there are over 5 trillion pieces of plastic in the sea, 92 percent of which are micro plastics.

Living in Utila I have witnessed nature at it's finest, unfortunately I often witness what we as humans are doing to the planet. I have seen first hand the affects plastic can have on small islands and costal communities. Often when you live in a city or in a land locked area you can often take for granted the effects that your actions have on the planet as a whole.

There are beaches where turtles nest that are covered in so much plastic that you can no longer see the sand. The first beach clean I attended in Utila left me speechless, shocked and upset. It is one thing watching videos online and reading an article about plastic pollution. It is a completely different feeling when you can see the destruction first hand. Plastic bags, spoons, toothbrushes, plates, bottles and bottle caps are some of the most common items you find.  When you attempt to collect the trash... you don’t know where to start. Do you collect all the big pieces? Do you collect all the small pieces? Do you collect everything you see? Picking up piece after piece as more washes up onto the shore. 

While on a dive with the Whale Shark and Oceanic Research Center (WSORC) we looked up to the surface to discover a huge mass of plastic floating above us. We did out best to collect as much of the plastic pollution as we could, even going back to the boat to collect nets as we could not keep it all in our hands. For me this video serves as a stark reminder of what our disposable culture and reliance on plastics is doing to our planet.

The moment we steer away from single use plastics a bottom up movement begins. It sends a signal to manufactures and businesses that we do not want their plastic. So my take home message is this: Please make it part of your routine to reduce your plastic and waste consumption to keep our planet as beautiful as it is for generations to come.

 Further reading: Ellen Macarthur foundation 2017 plastic report

Cover Photo Credit: A green sea turtle swims near plastic pollution in the Philippines. Photograph: Steve De Neef/Getty Images/National Geographic

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All forests have their own personality. I don't just mean the obvious differences, like how an English woodland is different from a Central American rain forest, or comparing tracts of West Coast redwoods to the saguaro forests of the American Southwest... they each have their own gossip, their own sound, their own rustling whispers and smells. A voice speaks up when you enter their acres that can't be mistaken for one you'd hear anyplace else, a voice true to those particular tress, individual rather than of their species. (at Matanzas Province)

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15 nov 17 

throwback to a couple of days ago! spent a slow weekend doing the things I love… it’s been a difficult week but still God is so faithful & merciful x 

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Plastic Pollution Pt.1

Plastic is a material we have begun to rely on heavily and use in place of many materials such as paper, metal, wood and glass. Plastic pollution is causing vast amounts of damage to marine environments and as the effects of plastic pollution draws more attention from scientists, public and the media many governments are finally begging to  implement laws to combat plastic based waste. Throughout this four part blog series we'll delve into the effects plastic is having on our planet and what we can do to help.

Modern day plastics began with Bakelite, the first fully synthetic polymer. It was lightweight, durable and could be moulded into an infinite amour of items. A 1924 article in Time magazine predicted that Bakelite was "material of a thousand uses". After this many types of synthetic polymers were developed however it was not until World War II when many natural materials became scarce that synthetic materials mass produced.

We now have many varieties of synthetic polymers which include polyethylene (used in plastic bags); polystyrene (used to make Styrofoam cups); polypropylene (used for fibers and bottles); polyvinyl chloride (used for food wrap, bottles, and drain pipe); and polytetrafluoroethylene, or Teflon (used for nonstick surfaces).

An Age of Plastic

Plastics are strong, lightweight and inexpensive which enables us to use them as a disposable commodity. In India 42% of the Countries plastic is used for packaging and Around one third of the words plastics are created for packaging alone.  Plastic has saturated the packaging sector for example: Planters® stated that there was “84% less packaging than glass jar by weight!” when the company replaced its glass jar for dry roasted peanuts with a recyclable plastic jar.  The company claimed that the switch would result in a 25% reduction in trucks on the road to ship the same amount of nuts, along with saving millions of pounds in packaging and shipping materials. For these companies using more material typically translates into higher environmental costs. Unfortunately these companies bare little responsibility for the environmental impact once the product has been sold to the consumer.

Once plastic's often single use need is complete, we allow 13 million metric tons of the material find its way into the oceans each year. In the ocean larger plastic debris that degrades into smaller and smaller pieces called micro plastics (less than five millimeters in length) with UV and wave  action accelerating this process. Many organisms mistake micro plastics for plankton and krill and eat them as food. Estimates suggest that there are over 5 trillion pieces of plastic in the sea, 92 percent of which are micro plastics.

Living in Utila I have witnessed nature at it's finest, unfortunately I often witness what we as humans are doing to the planet. I have seen first hand the affects plastic can have on small islands and costal communities. Often when you live in a city or in a land locked area you can often take for granted the effects that your actions have on the planet as a whole.

There are beaches where turtles nest that are covered in so much plastic that you can no longer see the sand. The first beach clean I attended in Utila left me speechless, shocked and upset. It is one thing watching videos online and reading an article about plastic pollution. It is a completely different feeling when you can see the destruction first hand. Plastic bags, spoons, toothbrushes, plates, bottles and bottle caps are some of the most common items you find.  When you attempt to collect the trash... you don’t know where to start. Do you collect all the big pieces? Do you collect all the small pieces? Do you collect everything you see? Picking up piece after piece as more washes up onto the shore. 

While on a dive with the Whale Shark and Oceanic Research Center (WSORC) we looked up to the surface to discover a huge mass of plastic floating above us. We did out best to collect as much of the plastic pollution as we could, even going back to the boat to collect nets as we could not keep it all in our hands. For me this video serves as a stark reminder of what our disposable culture and reliance on plastics is doing to our planet.

The moment we steer away from single use plastics a bottom up movement begins. It sends a signal to manufactures and businesses that we do not want their plastic. So my take home message is this: Please make it part of your routine to reduce your plastic and waste consumption to keep our planet as beautiful as it is for generations to come.

 Further reading: Ellen Macarthur foundation 2017 plastic report

Cover Photo Credit: A green sea turtle swims near plastic pollution in the Philippines. Photograph: Steve De Neef/Getty Images/National Geographic

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After many weeks of hard work my website is finally ready for you all. I can’t wait for you to read everything and I hope you learn something along the way.

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Welcome to my marine biology website. Get ready for lots of articles on marine life and follow my ocean adventures