FREQUENTLY ASKED QUESTIONS
1) Fish/Coral/Algae/Invertebrate Identification
2) Why is the Maine water brown and the Caribbean water blue?
Many visitors ask why there is such a dramatic difference between the color of the Maine water and the color of the Caribbean water. The brown color of the Maine water is due to the presence of tannins within the water. Tannins are byproducts of various biological reactions occurring within plants, such as kelp. Over time, tannins accumulate within the plants, where scientists think their unpleasant taste may deter animals from eating these plants. Eventually, however, the tannins are released from the kelp into the water, where they dye it brown. Visitors may be interested in knowing that tannins have many industrial uses, such as in making leather, dyes, and inks.
3) What is the difference between the backreef and the forereef?
Scientists have observed that coral reefs generally possess different zones, and these zones are usually dominated by different plants and animals. The zones are described mainly by two factors:
(1) depth, which determines how much sunlight the zone receives, and (2) location, which determines how close the zone is to the shore, the open ocean, and the other zones. Sometimes the distinction between the zones is readily apparent, but more often then not the zones overlap, making the distinction unclear. Furthermore, not all coral reefs possess the same zones.
In broad terms, these are the zones represented in our exhibit:
(1) The lagoon is the relatively shallow, calm water area that usually separates the shore and the backreef. It is usually dominated by grass beds (Thalassia in our exhibit) that typically serve as a nursery for many species of reef organisms. Here food and protection may be more readily available for the vulnerable young.
(2) The back reef is the shallow water area (0 to 5 meters) located between the shore/lagoon and the reef crest. It is typically a calm, protected area in which corals receive a lot of intense light from many directions. The area of the coral that receives the most light grows the fastest, and as a result, corals in this zone generally grow in forms that utilize the most light, such as heads, domes, or stalks that resemble fingers. These corals have adapted to exposure to high intensity light by possessing special pigments that absorb UV light and specially-adapted zooxanthellae, as well as being paler in overall color.
(3) The reef crest is the top of the reef, dominated by light-loving, fast-growing species that can withstand the force of the incoming waves, such as various species of Acropora.
(4) The fore reef is the area located on the ocean side of the reef; however, the term is usually used to describe the section of the reef that extends into deeper water (30 to 70 meters). The corals of this zone generally only receive light from one direction, above, and therefore tend to grow in a plate-like form to maximize the amount of light they receive. Deep water corals are darker in color to absorb what light is available and possess zooxanthellae that are adapted to low light levels.
4) Explanation of waves and their importance Waves are a form of energy - mechanical energy. The waves most familiar to people, those seen at the beach or along the shore, are produced by the friction of wind blowing across the water. As the wind pushes the water, energy is transferred from the wind to the water, creating what we call wind waves. However, not all waves are created by the wind. Earthquakes, landslides, volcanos, and even other waves produce waves, as the energy from each of these phenomenon is transferred to the water. Waves can occur at the surface of the water, or they may occur within the body of water itself.
Both tanks have a wave generator, the large box that sits above the deep end from which the waves are generated. It comprises two wavebuckets similar to those in the scrubbers, boxes with angled fronts that tip over when they are full with water and produce waves. These waves distribute food and clean, oxygenated water from the scrubbers. They also help prevent sediment from settling on the corals.
Water is fed to the wave generator via PVC lines from the refugia and scrubbers. Because the wavebuckets are different sizes, they dump at different intervals. This is done to control the force of the waves produced. The waves travel the length of the tank and are diffused by the wavecatcher in the reef tank and the intertidal area in the Maine tank, so as not to produce a counter-wave. The reef wavecatcher is a reservoir at the backreef end of the tank that contains the pump intakes.
5) Explanation of tides and their importance (exposure of intertidal organisms) Many organisms have adapted to an environment with a constant ebbing and flooding of the tide. In order to accurately reproduce the Gulf of Maine ecosystem, our model needed to include tides. The tides are an essential, non-living component of the Gulf of Maine ecosystem, much as the fish are an essential, living component. This is true in our exhibit and in the wild. The gravitational attraction between the earth, moon, and sun produces forces which result in tides. The sun and moon pull the surfaces of the earth toward them. This gravitational pull primarily affects the ocean surface, since it is very flexible. Spring tides occur during new moons and full moons, when a combined force from both the sun and the moon pulls on the oceans. The resulting tides are either very high or very low. Neap tides occur during the quarter phases of the moon, when the force from the sun and the moon cancel each other out. The resulting tides are much less extreme.
This ecosystem experiences two high tides and two low tides a day, as well as two spring tides and two neap tides a month.
Most of the food consumed in the system is produced in the system. Algae photosynthesize and make their own food, and then a wide range of herbivores, such as amphipods, sea urchins, and fish, graze on this algae. These herbivores are in turn consumed by the various carnivores. The small amount of food added to the system is mainly for the top predators in the systems (squirrelfish in coral reef system and pollock in rocky coast system). These animals would have a hard time finding enough food on their own, and they would prevent us from being able to have such a large amount of diversity in such a relatively small space.