Nautical Nest EarthCache

Almost every coastal area in Indonesia that is known for its marine life seems to have installed some form of artificial reef or reef restoration initiative.

CORAL REEFS

A coral reef is an underwater ecosystem dominated by reef-building, stony corals. Corals are tiny marine animals (an individual coral animal is called a polyp) that grow in groups to form colonies. Corals live in a symbiotic relationship with photosynthetic algae called Zooxanthellae, and need sunlight to survive. This is why corals are found in all the tropical oceans of the world, and why most corals live relatively close to the surface. Stony corals get their colour and most of their energy from their zooxanthellae (though they can also use their tentacles to prey on plankton passing by in the water column) and produce their own calcium carbonate skeleton. This provides a stable anchor to the sea floor. Reefs are formed by groupings of many colonies, sometimes of hundreds of different species within a relatively small area. The calcium carbonate skeletons of the corals (as well as silicon skeletons from sponges, sea cucumbers and other marine invertebrates) are the geological backbone of the reef. Most of these organisms are colonial, and the slow process of precipitation moves the living surface layer of the reef upward and seaward.

Coral reefs are under threat locally and globally.

Locally, threats come in many forms from various sources.  Physical damage or destruction resulting in coral being reduced to rubble may be caused by direct human behaviour such as coastal development, dredging, destructive fishing practices (such as dynamite or gleaning), boat anchors and groundings, and recreational activity (touching or removing corals). Physical damage can also occur naturally during storms (though these, too, may be indirectly worsened due to human impacts on global climate). After physical damage occurs to a reef, it 

Land-based pollution may also pose a threat to coral reefs.  There are many sources of pollution, including: sedimentation from irresponsible coastal management; nutrient influx from agricultural fertilizers; pathogens from septic systems; toxic substances in runoff from mining activities, landfills, or even from sunscreen used by beachgoers; trash and microplastics from improper disposal.

Global threats pose the greatest danger to coral reefs. Climate change is causing increasing atmospheric and ocean temperatures which stresses corals and makes them lose their zooxanthellae. Losing their symbiotic algae means corals lose their primary food source and also their colour, revealing the white calcium carbonate skeleton - a condition which is known as coral bleaching.  Altered ocean chemisty (increasing levels of CO2 in seawatermaking it more acidic) is also hampering the ability of corals (and other marine creatures with external skeletons, like crustaceans and shellfish) to form their skeletons.  Other climate impacts, such as sea level rise and increased frequency and intensity of tropical storms also constitute threats to reefs as we know them.

REEF RESTORATION

The best way to save the reefs is to protect them from the above threats in the first place. Prevention is always better than cure!  Sometimes interventions may help in more damaged or threatened areas and aid coral recovery, fish production, coastal defense and can be a benefit to recreational users as well. There are many different types of intervention and studies still have not definitely shown which type of substrate/structure is best for coral reef restoration, but the best method for any given project and place will depend on many factors.

Generally, reef restoration methods can be divided into biological restoration and physical restoration, though many projects include aspects of both.

Biological restoration involves transplanting of coral fragments or colonies from a donor site (maybe a healthy reef or a nursery) onto the restoration site.  Sometimes coral fragments will be tied or cemented to the new reef, and occassionally visible 'plugs' are inserted. This can kick-start the growth potential of an artificial reef, but is also very labour intensive.

Physical restoration involves reef repair and artificial reef installation. Artificial reefs are commonly employed as fish aggregating devices (complex habitats that attract fish). They also provide coastal defense benefits and stable substrate for coral settlement or transplanting. Artificial reefs use a variety of materials and can take many forms and there are several companies now producing modular components, including Reef Balls, BioRock and EcoReefs. Materials include natural rock, concrete, ceramic, rebar, metal mesh, and some even employ electric current.

The GILI MENO 'NEST'

This is one of the more unique ideas to provide some solid substrate onto which coral can settle and regrow, though the scale would have no significant 'sustainability' impact on the reef system or fisheries, and might be considered a pilot project to test the format. The sculpture is called “Nest” and was designed by artist Jason deCaires Taylor.

This feature is shallow enough that with extremely good visibility you might be able to figure out the answers to the on-site questions required for logging while snorkeling, but it would be better to be on scuba gear and regardless you will need a buddy.  As always, safety first when diving - this strait can have strong currents, and dives should be planned according to the tides. Also never touch anything on the reef, for your safety and its!  There may be hydroids, fire coral or other dangerous marine creatures on site, so be careful.

In order to log this earth cache, you will have to dive on the site to make observations.  Please message me directly with the answers to the following questions:

1. Examine the configuration.  Where do you think the name comes from?

2. Is this an example of a Physical and/or Biological Restoration project? How can you tell?

3. What material was used in the construction?  Why do you think this is this an appropriate choice as an artificial reef?

4. At the site, did you see any evidence that this installation is actually working as an artificial reef?  If so, what?  Name (or describe) at least one species of coral you saw growing on the man-made structures.  (Please document with photographs, if possible!)

5. Look at the reef surrounding this installation and describe it. How does it compare to the installation itself? What type of damage do you think occurred here?

6. How many horizontally-reclined 'pieces' are there? (Hint: This will be difficult in low-viz and you will likely need to leave your buddy at #1 and count each in turn, circling back around to the start).

We placed this cache during the times of Corona, so had not only the sculpture to ourselves, but the entire beach and (almost) the entire island!  Apparently, this is not usually the case, and it is advisable to beat the crowds by coming in the early morning hours. This is a public space and no entry fee is required.

Please go ahead and log the cache as soon as your answers are sent (no reply confirmation is required), however, note that ALL logs without accompanying answers WILL be deleted.