Keystone Species

Ever come home at the end of a long week at work, wondering how the place could function without you? It might feel like you’re the only one holding it all together, like a keystone. This week we’ll take a look at the keystone that holds an ecosystem together- keystone species. Without the keystone species, the ecosystem would collapse, or at least be severely altered.

Examples of keystone species are the gray wolf, limber pine, and sea otters. We’ll take a quick return trip to the lava fields of Idaho, then the kelp forests of the Pacific coast to see how limber pines and sea otters are the keystones of their neighborhoods. We learned about the gray wolf and the good work they do at Yellowstone back in September here.

The limber pine is one of the few trees I saw growing at Idaho’s Craters of the Moon National Monument and Preserve. Back in September I spotlighted Craters of the Moon in “Volcanic Idaho”. In that blog post, I mentioned the diverse ecosystem found there. Much of it centers around the limber pine. Limber pine is a pioneer, one of the first to colonize an area following a disturbance, such as a volcanic eruption in Idaho. Its seeds, needles, and sap feed a multitude of mammals, insects, and birds. Without the limber pine, those critters would have to live elsewhere in Idaho, maybe even Utah or Wyoming.

Limber pine at Craters of the Moon

Off the Pacific coast, one of the most important marine habitats is the kelp forest. The kelp hosts many species of fish, somewhat resembling a coral reef (sans coral, of course). The kelp also absorbs storm surge and carbon dioxide. However, kelp tastes delicious, at least according to sea urchins. Lucky for the kelp, sea otters think sea urchins are delicious. Without the otters keeping the urchins in check, the kelp forest becomes an undersea clear cut. Local biodiversity plummets.

River otters (Marine Mammal Commission)

Kelp forest with and without sea otters (Sea Otters.com)

This week's information comes from Great Ecology's blog on limber pines and Sea Otters.com

Species of the Month

This month’s species of the month was supposed to be a lichen called lipstick cladonia, but for being a widespread lichen there is very little information about it. So I changed it to something a little easier to research. This past weekend I saw my first eastern bluebird, so that’s what you get this month.

Scientific name: Sialia sialis

Kingdom: Animalia (animals)

Class:   Aves (birds)

Order: Passeriformes (perching birds)

Range: east of the Rockies from southern Canada to Honduras

Habitat: open areas with trees  

Lifespan: 6-10 years, mortality highest in first year

Diet: primarily insects, also seeds, nuts, and berries

Male bluebird with a cricket (Audubon Field Guide)

Predators: Snakes, house cats, raccoons, black bears, American kestrels. Flying squirrels and chipmunks are egg predators. House sparrows and European starling kill bluebirds and/or compete for nesting sites.

Conservation Status: no special protection

Male with brilliant blue on full display (Smithsonian)

Other Information: Bluebirds are a social, yet territorial bird. At times they gather in flocks, but will also defend a nesting territory and feeding territory from other bluebirds. They also have an interesting dynamic with tree swallows. Two pairs of bluebirds will not nest in boxes that are next to each other, and bluebirds will drive away tree swallows if only one box is available. However, placing two boxes side by side will allow the bluebird and the swallow to coexist as neighbors. Male bluebirds have a brilliant blue backside and red breast; females are dull gray with brownish breast. Her eggs are blue, but sometimes white, in clutches of 3-7. Eggs hatch after 13-16 days and the young fledge nest 2-3 weeks after hatching. Pairs may mate twice in a season, and sometimes the young from the first clutch will help raise the second clutch.

Female bluebird looking with muted colors (Cornell Lab of Ornithology)

Information this month comes from the good folks at University of Michigan's Animal Diversity Web again.

The Floor is Lava!

The Kilauea eruption in Hawaii has been making headlines recently, with hundreds of residents displaced on the Big Island. Let’s take a look at what’s happening there and why.

Volcanoes are vents into the center of the earth. Liquid hot magma in the mantle is forced upward to the crust by pressure. Once in a while, the pressure is great enough to force the magma out of the ground. We call it a volcanic eruption, and change the magma’s name to lava. Not all eruptions produce lava; in many cases gases and rocks are thrown from the volcano. Such was the case at Mount St. Helens in 1980 and 2004. This particular eruption isn’t even centered on the volcano’s summit crater. While there have been steam, ash, and rocks erupting from the summit crater, there hasn’t been a lava eruption there yet. Much of the lava is spewing from fissures, cracks that have opened in the ground.

Kilauea summit crater, May 9, 2018 (USGS)

 

Fissure eruption, Jan 3, 1983 (USGS)

Most of the world’s active volcanoes are at the edges of tectonic plates. To understand the concept of plates as they relate to volcanic activity, imagine the crust is thin pieces of rocks fit together and floating on top of the liquid magma mantle. The plates fit together but not tightly enough to keep some of the magma from oozing to the surface. In some areas, one plate is sliding underneath another. An example is the Juan de Fuca plate sliding under the North American plate in the Pacific Northwest. This action created the volcanoes of the Cascade Range. In other areas, the plates are pulling away from each other, as in the Mid-Atlantic Rift. The Eurasian and North American plates are separating, and the material coming forth from the seafloor is what gave us Iceland.

Map of the world's tectonic plates. The Ring of Fire
flanks the west coast of the Americas and east coast of Asia.
(Science Education Resource Center)

Ring of Fire volcanoes in Oregon (Universities Space Research Association)

Hawaii is in the middle of the Pacific Ocean, thousands of miles from the edge of the Pacific plate. Why the volcanic activity then? Hawaii sits on top of a hot spot. The hot spot is a leak in the ocean crust. The Big Island is the newest in the Hawaiian chain, and still growing as we can see. The hot spot has been leaking magma into lava for millions of years. The spot remains in place, while the plate slides along above it. That’s why Hawaii is a series of islands. The plate is moving to the northwest, so the islands are oriented from northwest to southeast. The current situation in Hawaii is even happening on the southeast side of the island. As time goes by, activity at Kilauea will cease and a new island will rise southeast of Hawaii.

Hawaiian hotspot (Smithsonian Institution)

Magnificent Mangroves

It’s common knowledge that trees are important. They provide oxygen, shade, habitat, food, and useful forest products. In tropical and subtropical areas, there is an important tree that is vanishing from coastal areas at an alarming rate- the mangrove.

Mangroves are annoying because they tend to live only at beaches that developers around the world want to develop. Mangroves are wonderful trees because in addition to the ecosystem functions they perform for nature, they also have ecosystem services for humans, if we would just leave them alone. They form a protective barrier against storm surges and trap sediments in their root systems, extending the coast outward as a buffer against sea level rise.

Mangrove forest (USFWS)

Mangrove species are able to tolerate brackish water. They have tall prop roots that keep the bulk of the tree above high tide. The root system slows water, allowing sediments to settle out. Eventually, enough sediment accumulates that the tree is on solid ground and new mangroves colonize the water in front. Small organisms like the safety that mangrove roots provide.

The tall prop roots are obvious at low tide (NOAA)

Mangroves are able to handle brackish water because they have a salt gland, so to speak. They excrete the salt through their leaves, bark, or roots. Some of the leaf excreters keep their leaves, which have a salty coating. Others accumulate salt in the leaf, and shed the leaf when it is saturated with salt. Those that excrete salt through their bark also use the shedding method to get rid of the salt.

Now that we’ve become aware of the mangroves’ benefits, we’re slowly making progress toward preserving the remaining forests. Here in the US, there are three mangrove species (red, black, and white) with a historic range being the Gulf coast and both of Florida’s coasts. Today, the best example of a mangrove forest can be in Florida at Everglades National Park. If you ever get to check out this important ecosystem, please do!

More great prop roots, this time on red mangroves (NPS)

This week's mangrove facts come from NOAA and American Museum of Natural History.

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.