Category Archives: Science

Being the main part of the blog, this page will feature short scientific reviews of general or personal interest, helping to bridge the gap between popular science outreach and formal research.

The Coastline Paradox

Video

How long is the coastline of Australia? One estimate is that it’s about 12,500 km long. However the CIA world factbook puts the figure at more than double this, at over 25,700 km. How can there exist such different estimates for the same length of coastline? Well this is called the coastline paradox. Your estimate of how long the coastline is depends on the length of your measuring stick – the shorter the measuring stick the more detail you can capture and therefore the longer the coastline will be.

Fractals are typically self-similar patterns that show up everywhere around us in nature and biology. The term “fractal” was first used by mathematician Benoit Mandelbrot in 1975 and used it to extend the concept of theoretical fractional dimensions to geometric patterns in nature, including the seabed.

Strange world of hydrothermal vents

Video

A hydrothermal vent is a fissure in a planet’s surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots. Hydrothermal vents exist because the earth is both geologically active and has large amounts of water on its surface and within its crust. Common land types include hot springs, fumaroles and geysers. Under the sea, hydrothermal vents may form features called black smokers. Relative to the majority of the deep sea, the areas around submarine hydrothermal vents are biologically more productive, often hosting complex communities fueled by the chemicals dissolved in the vent fluids. Chemosynthetic archaea form the base of the food chain, supporting diverse organisms, including giant tube worms, clams, limpets and shrimp.

The Endeavour Mid-ocean Ridge is an exciting study location because it is a place where new volcanic seafloor is constantly created at the spreading boundary between the Juan de Fuca and Pacific plates. The region (approximately 300 km off the British Columbia coast), has been the site of intensive investigation for more than 20 years.The Ocean Networks Canada Observatory, comprising VENUS and NEPTUNE Canada cabled networks, supports transformative coastal to deep ocean research and technology. It enables real-time interactive experiments, focused on ocean health, ecosystems, resources, natural hazards, and marine conservation. The Observatory is a national facility led by the University of Victoria for a pan-Canadian consortium of universities and partners.

NEPTUNE Canada’s real-time monitoring capability will benefit both ongoing and new experiments. Continuous data gathered before, during and after events like earthquakes and intrusions will be recorded across a coordinated suite of instruments both at the hydrothermal vents on the seafloor and within moorings extending 250m up into the 2,200m water column. A network of seismometers here and at other sites will provide high resolution information on tectonic processes such as earthquakes and strain across the Juan de Fuca plate.

via NEPTUNE Canada: Endeavour and Wikipedia.

Some more footage of the Endeavour ridge hot vents acquired using the ROPOS ROV. See also the BBC news report about a recent British expedition to the Cayman Trough to the deepest undersea vents.

Guest Post by Damien Guihen of British Antarctic Survey

Standard
Tabular Iceberg in the Antarctic Ocean

Tabular Iceberg in the Antarctic Ocean

My name is Damien Guihen and I work for the British Antarctic Survey in Cambridge, UK. I am an oceanographer and study the interaction of physical processes with biological systems. At the moment I am part of a project called GENTOO, which stands for Gliders: Excellent New Tools for Observing the Ocean. The project is named after a species of penguin and is a partnership between the University of East Anglia (UEA), the British Antarctic Survey, Caltech in the US and the University of Cambridge. Together we are trying to use special robots that dive as deep as 1000 m underwater to learn more about how the ocean works in the Antarctic and particularly around the Antarctic Peninsula, that part of land that juts out of the frozen continent and stretches towards South America.

The robots being used are called ocean gliders. These gliders use changes in an oil bladder to sink or float and have short wings that move them forwards. We put the gliders in the water for periods as short as a day or as long as six months. They are very efficient and can take measurements for long periods using a range of sensors. A glider uses a satellite to call home every time it comes to the surface. It phones a computer in the UK and uploads its data. Then it asks for new instructions. This way, we can see the data very quickly and can control it from anywhere in the world.

Damien with an ocean glider

Damien with an ocean glider

Ocean Glider deployment map

Ocean glider deployment map shows the path taken by the ocean glider, west of the South Orkney Islands. The breaks between the red lines are when the glider is at the surface

The partners in the project are investigating different aspects of the ocean. UEA are using the high resolution temperature and salinity data from gliders to understand the different layers of water and how they interact. The Southern Ocean is very cold and dotted with countless icebergs, great and small. The cold causes water to sink and this sinking drives a lot of ocean flows. Using the glider allows UEA to take hundreds of thousands of measurements that help them to build a better picture of what is happening. Caltech are using the gliders, along with some floating instruments called drifters, to measure how the water in the southern ocean is mixing and moving. They have tracked some drifters for thousands of kilometres, from the Antarctic Peninsula to South Georgia. The University of Cambridge team are using the data collected to help build better mathematical models of how the water moves so that they can better describe and predict the mixing, particularly on slopes and near the icebergs.

At the British Antarctic Survey, we are using a special instrument that has been built into the glider. The instrument, called an echo sounder, sends little pings of sound. It then listens to the echo that comes back from small animals in the ocean. As the glider moves around, we collect a lot of data from the pings in different locations and at different depths. We can then use this data to build a picture of the distribution of these animals throughout the ocean. Using the data from the other groups, we can get a better idea how the ocean currents push the animals about and how a changing climate might effect the Antarctic marine ecosystem.

king penguins

King penguins

Working on a ship or a base in the Antarctic is always fascinating. Sometimes we have to crash our way through thick ice to get to where we need to go. We see a lot of ice bergs too and each one looks different. We often see large storms that keep us up at night as the ship rolls its way through big waves. We are fortunate too to see a lot of wildlife such an albatross, giant petrels, cape petrels, skuas, orca (killer) whales, elephant seals, crab-eater seals, Weddell seals, fur seals, and penguins such as gentoo, chinstrap, king, Adele and Magellanic. It’s a wonderful experience and each time I come back I count the days until I can go again.

Albatross in the sunset

Albatross in the sunset

A very big thank you goes out to Dr Damien Guihen of the British Antarctic Survey for sharing his experiences and photographs from the Antarctic with us the readers of this blog! The post has given a fascinating insight into the work of BAS in one of the most remote and undiscovered continents on the planet.

The Story of Sharks

Video

This film, through humor, simplicity, and scientific theory, describes our predicament with a drastically declining shark population worldwide, and offers a new perspective on how to view the most feared fish on our planet. Through stop motion, we tell the story of our ocean’s greatest predators by focusing on the vital role they play in our economies, ecosystems, and cultures. It is the story of our decision between an ocean with, or without, them. It is the story of how we only have one logical choice left. It is the story of sharks.

Bioluminescence

Video

Walking along the beach at night or sailing on a darkened sea, you will often see sparkling lights in the water. This is bioluminescence—the emission of visible light by an organism as a result of a natural chemical reaction. A remarkable diversity of marine animals and microbes are able to produce their own light, and in most of the volume of the ocean, bioluminescence is the primary source of light. Luminescence is nearly absent in freshwater, with the exception of some insect larvae, a freshwater limpet, and unsubstantiated reports from deep in Lake Baikal. On land, fireflies are the most conspicuous examples, but other luminous taxa include other beetles, insects like flies and springtails, fungi, centipedes and millipedes, a snail, and earthworms. This discrepancy between marine and terrestrial luminescence is not fully understood, but several properties of the ocean are especially favorable for the evolution of luminescence: (a) comparatively stable environmental conditions prevail, with a long uninterrupted evolutionary history; (b) the ocean is optically clear in comparison with rivers and lakes; (c) large portions of the habitat receive no more than dim light, or exist in continuous darkness; and (d) interactions occur between a huge diversity of taxa, including predator, parasite, and prey.

via Haddock, Moline and Case (2010), Bioluminescence in the Sea – Annual Review of Marine Science, 2(1):443.

References and Further Information

Seagrasses

Standard

They are an ancient species of flowering plants that grow submerged in all of the world’s oceans. Seagrasses link offshore coral reefs with coastal mangrove forests. Today, these “prairies of the sea,” along with mangroves, are on the decline globally. Scientists fear the diminishing vegetation could result in an ecosystem collapse from the bottom of the food chain all the way to the top.

Known as “hotspots of biodiversity,” seagrasses and mangroves attract and support a variety of marine life. However, worldwide damage and removal of these plants continue at a rapid pace. Changing Seas travels along Florida’s coastline to get a better understanding of the significant roles mangroves and seagrass play within the state. Can biologists prevent a negative ripple-effect throughout the marine food web before it’s too late? How will rising sea levels impact these plants as well at the communities that depend on them?

via “Seagrasses & Mangroves”.

For further information on the Seagrass Watch program, please see the link and also “Ancient seagrass” for an article about seagrasses over 200, 000 years old.