Reef Madness

Last week we explored the dynamic barrier islands, a great place for wildlife and a popular vacation destination. This week, we venture beyond the island into the coral reefs just offshore. As an avowed landlubber, I'll probably never get to see a coral reef for myself, but I'll live vicariously through myself telling you all about them.

Coral reef (Smithsonian)

Coral reefs are hard, rocky structures made of the skeletal remains of what was once living coral. Corals are a marine animal, not a plant, and the best-known form a symbiotic relationship with algae. Because algae needs sunlight for photosynthesis, many coral reefs are found in clear, shallow water. Cold water corals that live in the deep sea. Without sunlight, these organisms filter feed plankton. Because of their inaccessibility, we are still learning about them.

Coral polyps (NPS)

The most popular corals are the shallow ones, because they are relatively easy to reach. Scuba diving, snorkeling, and even glass bottomed boats bring humans right to the biological hot spots. People are drawn to coral, not just because of the beauty of the coral itself, but the amazing biodiversity found within the reef. Fishes, crustaceans, sponges, anemones, and countless other sea creatures call the reef home. The coral structure provides hiding places for mobile critters and anchorages for sessile ones. Hiding places benefit predator and prey alike- they provide somewhere to hide from bigger fish, or place to launch a quick strike at an unsuspecting meal.

Coral reef (NPS)

Cold water corals provide the same habitat and ecosystem, and may be even more important than their shallower counterparts. Most sea life can be found near the coast and relatively shallow. Corals in the deep sea for a sort of island in an area that is otherwise mostly devoid of life.

Deep sea cold water coral (Joint Nature Conservation Committee)

Like just about every ecosystem in the world, coral reefs are in trouble. Coral is dying as sea temperatures and carbonic acid levels rise. The algae component of the coral either dies or evacuates in a process known as coral bleaching. Some corals show some resistance to slightly warmer temperatures. Research into this is continuing. If you ever get a chance to explore coral reefs, either by boat or underwater, remember to look but don't touch.
This week's information comes from NOAA and the Smithsonian Institute.

Species of the Month

Wherever you live, fishing season is in full swing. This month we'll profile one of the most common game fishes, the rainbow trout. They can be found in lakes and streams almost everywhere around the world, though introduced to many of them.

Rainbow trout (State Department)

Scientific name: Oncorhynchus mykiss

Kingdom: Animalia (animals)

Class: Actinopterygii (ray-finned fishes)
Order: Salmoniformes 

Range: Pacific coast of North America from Alaska to Mexico

Habitat: Aquatic, some also have a marine phase

Lifespan: 6-8 years average, up to 11 years
Diet: Insects, insect larvae, crustaceans, small fish, algae
Predators: Lampreys, eagles, osprey, herons, mergansers, bears, mink, river otters, seals, sea lions, other fish, humans

Fish on! (NPS)

Conservation Status: No special protection for freshwater only fish; nine populations of steelhead are listed as threatened or endangered

Steelhead (NOAA Fisheries)

Other information: Rainbow trout get their name from a colorful iridescent streak along the sides of its body. State fish and game agencies around the country raise them to stock streams and lakes for fishing season. Stocked trout remain in freshwater; some native trout along the west coast are anadromous (have a saltwater phase) and return to their birthplace to spawn and die. The anadromous trout are called steelhead. Females lay eggs in a gravel nest called a redd. Fertilized eggs hatch after a few weeks, and the hatchling remains attached to the yolk sack as a food source before leaving the redd for the wider world. Young trout tend to stick to slower, shallow water. Young steelhead remain in the stream for up to three years before heading out to sea. Due to habitat degradation and loss, several western steelhead species are listed as threatened or endangered under the Endangered Species Act. Meanwhile, introduced trout are becoming a problem in some areas. They eat and/or outcompete native fishes such as cutthroat and brook trout. They threaten genetic integrity by hybridizing with native species. They also carry a parasite responsible for whirling disease, which causes deformities that make a fish easier prey.

Steelhead (NOAA Fisheries)

This week's information comes from University of Michigan's Animal Diversity Web and the US State Department, of all places.

Dead Zones

This week we’re taking a look at a problematic summer tradition: hypoxic dead zones. These are marine or aquatic areas that don’t have enough oxygen to support life. The most famous is probably the dead zone in the Gulf of Mexico. Let’s look at dead zones, how they form, and what you can do to help prevent them.

The most common cause of dead zones is excessive nutrient runoff. Nutrients in this case are nitrogen and phosphorus, nutrients from plants. The main source of this nutrient runoff is agriculture, but it can also come from detergents, animal waste, and untreated sewage.

Gulf of Mexico dead zone (Digital Journal)

The nutrient overload leads to a sudden population boom in the local algae community. It seems paradoxical that algae, which produces oxygen, leads to an area without oxygen. First, when a large mat of algae covers the water’s surface it prevents oxygenation at the water/air interface. Then, when the algae dies and decomposes, that is where the oxygen disappears to. Mobile critters like fish can move to more oxygenated areas to survive, but something that can’t move or is very slow like a starfish or sea urchin will suffocate unless the situation clears up.

How a dead zone forms (Gulf Hypoxia)

Sometimes the algae bloom is of a type that produces toxins. Sometimes the toxins cause fish kills. Shellfish can absorb the toxins through filter feeding and pass them on to predators and people. Algae toxins can even threaten public drinking water.

A closer look at an algae bloom (NOAA)

How can you help? Trying to stop non-point pollution seems hopeless, but if everyone ups their game a little bit it adds up and makes a difference. Simple steps you can take at home include limiting the amount of fertilizer you use for your lawn and garden, cleaning up after your pup, and washing your car in the grass rather than the driveway or street. Reducing fertilizer use reduces the amount of excess nitrogen and phosphorus washing into the storm drain and out to sea. If you’re already doing that, buy organic produce which doesn’t use any fertilizer or pesticide. Picking up your dog poop keeps the nitrogen and phosphorus from that source out of the system as well. Washing your car in the yard lets the phosphorus in the detergent soak into the yard rather than washing into the storm drain. Every little bit helps.

This week's information comes from the EPA.

This is a Crappy Subject

Now for the dirtier side of nature. Pretty much every living thing on this planet exists to be someone else’s meal. If you’re unlucky enough to become lunch, the next step is you become poop. No one likes to talk about it, look at it, or smell it. Even though it’s gross, it’s an essential element of the environment for a couple of reasons.

Raccoon scat

The most important function of poop, or scat as we call it in the science world, is a key role in the nutrient cycle. Every living thing needs an assortment of minerals in order to function properly. Minerals are absorbed from the soil by plants, then absorbed by herbivores that eat those plants, then absorbed by various levels of carnivores up through the food chain. Some minerals are present in the ground in rocks; others are returned to the soil through decaying organic matter (plant or animal) or through scat.

Nutrient cycle (from Exploring Nature.org)

Another important impact scat has on the environment is negative, and it goes beyond getting on your shoe. Nitrates and phosphates are common in scat, and also happen to be active ingredients in fertilizer. Excessive nitrates and phosphates in storm runoff causes high nutrient levels in lakes, streams, and even the ocean. Those high levels can cause an overgrowth of algae. Too much algae, even though it produces oxygen, can cause dead zones of little to no oxygen when the algae dies and decomposers feasting on it suck all the oxygen out of the water.

Algae bloom (Michigan Radio)

A third way scat is important is as a research tool. It allows people like myself who rarely observe animals in the wild to see what animals have been down the trail before. DNA samples can be pulled from scat, and population biologists can estimate population by counting turds. Ecologists can study an animal’s dietary habits from looking at scat.

The coyote that dropped this deuce ate a bird

Deer scat

Now that you’ve seen the usefulness of animal scats, maybe you will look at it in a whole new light on your next foray into the woods. Like anything else in nature (except maybe spiders), if you can overcome your aversion, you can learn to appreciate it.

I'm Lichen This Blog

This week Nature Minute will take a look at another unsung hero of ecology, the oft-overlooked lichen. There are many different lichens and they can be found just about everywhere. You’ve probably seen lichens. Maybe a greenish-gray circular spot on a rock, or on the bark of a tree (mistakenly referred to as moss).

Last year, I did a two-part series on the importance of soil. Lichen is just as important to life, if not more so, because lichen will frequently colonize bare rock and secrete chemicals that break down the rock. Thus begins the making a toehold for more advanced plant life to follow. This succession is the beginning of soil formation.

Notice above I said “many different lichens” and not “many species of lichens”. That was intentional, because while a lichen is a living organism, it is not a single species, but a symbiotic odd couple relationship between a fungus and an alga (singular of algae). Some lichens will have a green alga, some will have a blue-green alga, and still others will have both.

How does this crazy living arrangement work? The fungus provides the lichen’s structure. The algae provides the food through photosynthesis. In many cases, the fungus and the alga are perfectly capable of living on their own. Yet for some reason, sometimes they chose to live as roommates in a lichen apartment. There must be an evolutionary advantage.

Perhaps it is the chemicals produced by lichens. Very few insects munch on them, although tundra animals will. They are also very hardy, able to withstand complete desiccation. I don’t know of any fungi or algae that can do that on their own.

Because of the separate living components of lichen, it is impossible to trace the evolution of lichens like we can trace other organisms through DNA and the fossil record. So scientists can’t say how this unlikely partnership formed, although they can tell us how new lichens are made. Because it’s different species living together, you can’t just have a male lichen mate with a female lichen. The fungus and alga can reproduce individually, but their offspring won’t necessarily form a new lichen. However, the lichen can form a soredia, a group of the alga’s wrapped up in filaments provided by the fungus. This little ball of oddities rolls off and starts a new lichen. Another way for lichens to “reproduce” is for a piece of lichen to flake off and drift to a new home.

I hope you enjoyed this week’s fascinating look at one of nature’s weirdest partnerships. Now that you know how weird those mundane little blotches are, maybe you’ll take a closer look. Enjoy some lichen photos I’ve taken during my sojourns. Lichen information this week comes from the USForest Service and the University of California’s Museum of Paleontology here and here.

Lichen on a rock in Idaho

Lichen on a rock at Yellowstone NP

Several small patches of lichen on a rock

Lung lobaria lichen on a tree in Washington

Lichen in the branches of a tree in Washington

Lipstick cladonia on a tree stump

False pixie cup on a tree stump