The Impact of Marine Debris:


“Marine debris is defined as any persistent solid material that is manufactured or processed and directly or indirectly, intentionally or unintentionally, disposed of or abandoned into the marine environment or the Great Lakes” - National Oceanic and Atmospheric Administration (NOAA)

Pipe fish sailing in a straw in Koh Tao (Thailand)


In short, marine debris can include anything— ranging from fishing nets, lines, plastic bottles, to glass.

And it has a catastrophic effect on marine life.


But first of all, where does it come from?


The overwhelming majority of marine debris results from human activity, and nearly 80% of marine debris originates from land-based sources. There are no confirmed estimates about how much marine debris is in the ocean, but research voyages across the globe have found expansive patches of garbage accumulating in the ocean as a result of ocean currents.

One of the most prominent garbage patches found in the North Pacific Gyre, referred to as the Great Pacific Garbage Patch, has increased 5-fold in the last 10 years. It is estimated to be one to two times the size of Texas, USA.

Marine debris may enter water sources directly from a ship, or indirectly when washed out to sea via rivers, streams and storm drains. It can travel for hundreds of thousands of miles on ocean currents, posing a threat to ocean ecosystems and wildlife along the way. People may contribute to the accumulation of marine debris by:


  • The inappropriate disposal of trash from land-­based activities;
  • Release of waste from shore­based solid waste disposal and waste processing facilities;
  • Abandoning fishing gear, including line, nets, ropes, bait boxes, fish tags and trawl floats;
  • Intentional or inadvertent discharge of trash, galley waste and boating materials;
  • Inappropriate handling of undersea exploration and oil and gas extraction items.




Much of the marine debris found in oceans do not decompose in seawater and can remain in the marine environment for many, many years. Depending on the material, some products may even remain in the ocean for tens of thousands of years!

In coastal areas, especially in coral reefs, fishing gear is prone to trap and even kill marine animals, a phenomenon known as “ghost fishing. Fishing line or nets, strapping bands or even plastic, six-pack rings can greatly affect the mobility of marine animals. Once entangled within marine debris, the animals can have trouble eating, breathing or swimming, all of which can have fatal results. Many animals can choke on small, everyday items, mistaking them for food. A prime example is plastic bags; sea turtles often mistake the plastic bags for jellyfish and attempts to eat them, eventually choking and suffocating to death. Furthermore, many endangered albatross birds and chicks have been found dead with stomachs full of plastic, including bottle caps and cigarette lighters. Even if the animal does not immediately choke to death, the debris within their stomachs can give them a false feeling of being full, and so the animal may die of starvation as a result.



Furthermore, marine debris can provide a habitat for marine species, such as oysters, barnacles, or plants, to collect upon. As debris is carried away by the currents, the organisms living on the debris are carried along far distances and may potentially end up in a completely new environment. Some of these organisms can become an invasive species in the new area they are in, and thus have a negative effect on the native species.


Marine debris also leads to microplastics— an issue that is recently gaining traction across the world; they are classified as plastic particles less than five millimeters in length, and they have a huge negative impact within the marine ecosystem, and for humans. Because is is still an emerging field of study, not a lot is known about microplastics and their long-term impacts yet. However, the current findings show a growing problem.


The worst part, the microplastics:

Plastics degrade incredibly slowly, often over hundreds, and if not, thousands of years. The biggest problem is that they are ingested by many marine organisms, and therefore the plastics have a tendency to move within the food web. Contaminated plastics can break down into small pieces resembling food—such as plankton—for the animals to eat, become embedded in animals' tissue through ingestion or respiration, and sink towards the bottom of the ocean, from where they may be ingested by bottom feeders. The plastic debris ingested by animals can absorb many toxic, hormone-disrupting chemicals like Polychlorinated biphenyls (PCBs) and Dichloro-Diphenyl-Trichloroethane (DDT) which resides in seawater. When the plastics are ingested by marine species, they are spread into the food chain and can affect many marine animals. Studies in the North Pacific Central Gyre, where the Great Pacific Garbage Patch is, found that approximately 35% of the fish had ingested plastic.


Unfortunately, corals are also affected by microplastics. Recent experimentation shows that Scleractinian corals, which are primary reef-builders, may ingest microplastics under laboratory conditions. While the effects of ingestion on these corals has not been conclusive, corals can easily become stressed and bleach; microplastics have been shown to stick to the exterior of the corals after exposure in the laboratory, which can potentially be harmful as corals cannot handle sediment or any particulate matter on their exterior. The coral, in turn, slough it off by secreting mucus, and they expend a large amount of energy in the process, increasing the chances of mortality.

Main references:

By Ning Jiang



Weather, climate and environment; the crucial engagement

"Anything else you are interested in is not going to happen if you can't breathe the air and drink the water. Don's sit this one out. Do something. You are by accident of fate alive at an absolutely critical moment in the history of our planet" - Carl Sagan


The climate change project on Koh Tao aims to further understand the changes in climate and ocean parameters around the island and in the future, the aim is to also be able to identify any effects of these changing parameters and how they are being influenced by climate change and global warming.

We can use past climate records to predict future changes but with the current data constantly being recorded by the weather station, hopefully it will be possible to explain any changes occurring in those predictions. On Koh Tao, measurements that are being taken include wind speed and direction, precipitation or rainfall and atmospheric pressure and humidity. These parameters could give a good indication of a storm system. With climate change there is evidence for increasing storm intensity and potentially frequency however little research has been conducted around the island of Koh Tao about the influences this could have on the island ecosystems including coral reefs. Changes in these parameters cause fluctuations in mixing and vertical gradients and fronts.

Other ocean parameters being recorded include water pH, salinity, dissolved oxygen, nutrient content and temperature. All these factors influence each other and are related to the atmospheric conditions. The ocean-atmosphere circulatory system is important in controlling the ocean environments. For example, with an increasing atmospheric temperature, the ocean temperature will rise. This means less gases are absorbed and so more carbon dioxide may remain in the atmosphere contributing to the ozone layer, along with other effects of a warming climate, including melting icecaps and increased ocean salinity.

As we pump more greenhouse gases into the atmosphere (measured on the weather station as equivalent CO2), we will be able to track the influence this has on the ocean parameters, for example increasing CO2 absorption into the ocean will cause the pH to decrease, this process is known as ocean acidification and can have adverse effects on many organisms in the ocean including calcifying corals and plankton. These projects of Koh Tao and around the world should help us understand the local changes in environment and maybe how specific areas of the world are effected in different ways.

One of the other negative changes to the environment is the increasing introduction of plastics and micro plastics into the environment. With an understanding of the currents around Koh Tao for example, we may be able to identify areas more negatively affected than others, or how these plastics are transported and where if anywhere they accumulate.

By monitoring the weather in Chalok and potentially in the future other locations around the island and progressively the world, and relating them to changes in water quality, we can potentially further understand certain effects of events such as storms, introduction of micro plastics and increasing atmospheric greenhouse gases and hopefully find a way to help ecosystems such as coral reefs cope with such devastating changes in the future. This information can be used globally in order to identify areas at most risk of these anthropogenic changes, but more positively, areas suitable for artificial reefs, coral restoration and clam and sea turtle head starting programs.

  • The weather station:


  • Some pictures of the breathtaking Chalok Bay... enjoy!


During the months of March, April and May small tornados can show up in the horizont
High tides are common during the first part of the year around Koh Tao when the sun is in the farthest point from the Earth
Raileigh dispersion happends when the sun is near the sunset, the sun rays needs to go across a thick atmosphere therefore changes in colours creating breathtaking sunsets
Extra Low tides happen at the beguining of summer when the sun is closest from the earth, this could be worse when the Monzoon starts in the mainlands, low preasures in Thailand move the water to the main coastline and it looks like the water is definitely gone!


Post written by: Jess Harding

visit our team:



Water Quality Elements Project

Water Quality Elements Project



With every drop of water you drink, every breath you take, you’re connected to the sea. No matter where on Earth you live”  Sylvia Earle

It is difficult to imagine the amount of water that makes up our oceans. Some studies speak of 1,332 million cubic kilometres; however, it is very difficult to know that for sure. What is certain is that the quality of this water has a direct influence on the life quality of its inhabitants.

Innoceana arrived at the coasts of the Gulf of Thailand with a clear idea. We wanted to understand the state of the ocean water by collecting water samples from the surrounding areas of the Island of Koh Tao and analysing them, as well as to try involving more people to continue to do so to create an initial database or "baseline" of the quality of this water. Today, five months later, we have got more than a hundred samples which have been collected from the main diving sites surrounding the island. The analysis of these samples has also allowed us to find two possible “dead zones”. What is more important is that the project has been expanded and today we work alongside different diving centres that have joined our cause. These centres are now buying their own sampling equipment and have begun to analyse the water quality with the purpose of contributing to the database managed by Innoceana and following the methodology that Innoceana created.

There are many parameters that can be measured in water and which are key to the survival of the wonderful living beings that ply the oceans. Temperature, pH, salinity, nitrates, phosphates and oxygen are just some of them. In this blog we are going to try to explain the reason for their importance:

Temperature: Seawater’s temperature (as it happens on land) varies from the equator to the poles where its minima is produced due to solar radiation which has a direct influence on its temperature. The current climate change is generating a dramatic increase in temperatures due to greenhouse gases and the destruction of the ozone layer.

Animal corals are ectothermic, thus leading to them being sensitive to temperature changes. Very low temperatures disable corals from making metabolic reactions necessary for them to survive, however, very high temperatures can also be a threat. When temperatures rise, the coral’s inner body becomes more acidic and toxic to the zooxanthellae, which commence to produce higher amounts of waste in the form of free radicals. The necessity to protect themselves from these free radicals, leave no other alternative to the animal coral but to eject the zooxanthellae in a process called coral bleaching. Bleached corals live only with 5 to 15% of their regular energy levels until environmental conditions return to normal levels and a new zooxanthellae moves into their bodies. However, corals do not often have enough energy to survive this period and die.

Hard corals survive in waters with temperatures ranging from 18 to 36oC, however they are healthiest in temperatures ranging between 22 to 28oC. In temperatures above 30oC, corals struggle to survive and begin to die gradually in most cases. Below 18oC, reef-building corals begin to decline rapidly.

All species of sea turtle are also affected by climate change. An increase in nesting temperature have an impact on sea turtles as they rely on the sand temperature in which the eggs are incubated to determine the gender of the hatchlings. Due to this, 99% of sea hatchlings are turning females resulting in lack of males which in turn affects reproductive rates.

PH: An increase in atmospheric carbon dioxide (CO2) concentrations had led to oceans becoming more acidic, thus, decreasing water pH concentrations from 8.2 to 8.1 units. Studies have shown that corals are more likely to be healthier in seawater with pH levels between 8.0 and 8.3 units, as lowered pH levels lead to reduced calcification rates thus, growth rates. Therefore, pH becomes an indicator of water acidity which can be measured in logarithmic scale bounded between 0 and 14, pH 1 as is the case of hydrochloric acid can kill a human being with a single sip.

Salinity: Corals need salt water in order to survive. They require salinity concentrations in water between 32 to 34ppm as they are highly susceptible to disease leading to rapid coral bleaching in lower salinities which is mainly caused by near river openings, continuous heavy rains, and poor or excessive drainage in coastal areas. Salinity is measured by density or by parts per trillion (ppt) which is usually around 1.023 kg / litre. Salinity also affects other organisms such as fish that use an internal host regulation system. Changes in the salinity not only affect sea life but also produce changes in marine currents.

Nutrients (Nitrates and Phosphates): Coral reefs thrive best in areas with low nutrient levels, also known as oligotrophic waters, due to the fact that nutrient rich waters encourage macro algae growth, which is one of the major threats to corals. Macro algae grow much faster than corals competing with them for space, shading and smothering them. High nutrient concentrations also favour the increase of coral predators such as Drupella snails (Drupella cornus) and Crown of Thorns starfish (Acanthaster planci). The major nutrients of concern are compounds of nitrogen and phosphorous such as nitrates (NO-3) and phosphates (PO4) which are present in soil and especially concentrated in human sewage.

When these nutrients reach the sea, a phenomenon called "algae bloom" consisting in an uncontrolled growth of algae occurs resulting in dead zones. To date, Innoceana has located two possible dead zones in the Island of Koh Tao.

O2: Oxygen is fundamental for all life organisms, however, unlike terrestrial species, most underwater creatures use gills to filter dissolved o2 in water. When dissolved o2 levels are too low, underwater breather species must migrate from these areas in order to survive. This is the case of the so-called dead zones. o2 levels below 2 parts per million (ppm) or mg / litre, make survival of most aquatic organisms impossible.

 Source –


Turbidity: Turbidity indicates levels of suspended particles in water which can be directly linked to sea currents, to the type of substrate (muddy substrates lead to high turbidity, thus, blocking the entrance of natural light), or to nutrient levels that promote microalgae formation and growth. In the Island of Koh Tao, it is common to see high turbidity levels after rainy days due to the silt and other particles that the rain drags into the sea. Turbidity can be measured vertically from a boat and horizontally underwater, both by using the Secci disk which is obtained as a result of the refraction and diffraction studied centuries ago by Snell. Areas with high turbidity may be unhealthy specially for corals but also areas with very low turbidity may be a symptom of dead zones.


Innoceana has designed a low-cost measuring kit (150 euros) which can be used to analyse water quality in a very simple way. In addition to this, we have also designed a system to help every diving centre that would like to participate in the collection of data (There are already 10 centres interested on the project and 3 centres have already bought their measuring kit). This system consists of the following:

  1. Cover Letter (pdf): Koh-Tao-WQA
  2. Protocols (pdf): KTWQ Elements Protocol V3
  3. Contract of commitment (pdf): WQEKT-SOU
  4. Measurement kit: