Vernal pool
Encyclopedia
Killifish
A killifish is any of various oviparous cyprinodontiform fish . Altogether, there are some 1270 different species of killifish, the biggest family being Rivulidae, containing more than 320 species...
es) have adapted
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
to this habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
specifically, however.
Most pools are dry for at least part of the year and fill with the winter rains or snow melt. Some pools may remain at least partially filled with water over the course of a year or more, but all vernal pools dry up periodically.
They are called vernal pools because they are often, but not necessarily, at their peak depth in the spring ("vernal" meaning of, relating to, or occurring in the spring).
Despite being dry at times, once filled they teem with life. The most obvious inhabitants are various species of frogs and toads. Some salamanders also utilize vernal pools for reproduction, but the adults may visit the pool only briefly. Other notable inhabitants are Daphnia
Daphnia
Daphnia are small, planktonic crustaceans, between 0.2 and 5 mm in length. Daphnia are members of the order Cladocera, and are one of the several small aquatic crustaceans commonly called water fleas because of their saltatory swimming style...
and fairy shrimp
Fairy shrimp
Anostraca is one of the four orders of crustaceans in the class Branchiopoda; its members are also known as fairy shrimp. They are usually long . Most species have 20 body segments, bearing 11 pairs of leaf-like phyllopodia , and the body lacks a carapace...
, the latter often used as an indicator species
Indicator species
An indicator species is any biological species that defines a trait or characteristic of the environment. For example, a species may delineate an ecoregion or indicate an environmental condition such as a disease outbreak, pollution, species competition or climate change...
to decisively define a vernal pool. Other indicator species, at least in New England, are the wood frog, the spadefoot toad, and some species of mole salamanders. There may be vegetative indicators of vernal pools but further study must be conducted to verify the relationships between vernal pools and their characteristic flora and fauna.
In some northern areas, tadpole shrimp are also common.
Soils
The underlying soils of the vernal pool are a fundamental part of the vernal pool habitat. These soils are often referred to as hydric. In most cases there is a hard pan layer which causes the retention of water in the pools. The entire process of the normal soil turning into hydric soil is often referred to as "base retention". Professor Kenneth Pearson first discovered this process in 1856 when he found a body of water that had suddenly appeared after a rainy day in what is today LeominsterLeominster
Leominster is a market town in Herefordshire, England, located approximately north of the city of Hereford and south of Ludlow, at...
, Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
. He noticed the water had remained for about 3 weeks, and wondered why this was. When he studied the samples of soil he had retrieved from the site, he named the process "base retention" for the soils conversion into a retentive state.
Flora
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...
s created by acidity and salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
gradient
Gradient
In vector calculus, the gradient of a scalar field is a vector field that points in the direction of the greatest rate of increase of the scalar field, and whose magnitude is the greatest rate of change....
s.
Different species are suited to different moisture levels, and as water evaporates from the edges of a pool, rings of flowers blossom around it. The color patterns change as the wet season wears on. The rings may form swirls and layers, with the green of new grass surrounding the whole pattern.
Flora commonly found at vernal pools include Downingia
Downingia
Downingia is a genus of 13 annual plants native to western North America and Chile. Commonly known as "calicoflowers", they are notable for forming mass displays of small but colorful blooms around vernal pools...
and lupin
Lupin
Lupinus, commonly known as Lupins or lupines , is a genus in the legume family . The genus comprises about 280 species , with major centers of diversity in South and western North America , and the Andes and secondary centers in the Mediterranean region and Africa Lupinus, commonly known as Lupins...
e species, yellow pansies
Yellow Pansy
Viola pedunculata, the Yellow Pansy, is a common and attractive wildflower of coastal regions of California and Baja California. It is also known as the California Golden Violet, or as the Johnny Jump Up, though the latter name is more usually associated with the introduced Heartsease, Viola...
, several sweet-scented clover
Clover
Clover , or trefoil, is a genus of about 300 species of plants in the leguminous pea family Fabaceae. The genus has a cosmopolitan distribution; the highest diversity is found in the temperate Northern Hemisphere, but many species also occur in South America and Africa, including at high altitudes...
s, a variety of goldfields
Lasthenia
Lasthenia, commonly known as goldfields, is a genus of the botanical family Asteraceae. The genus is named after Lasthenia, a cross-dressing female pupil of the ancient Greek philosopher Plato.-Description:...
, button parsleys
Eryngium
Eryngium is a genus in the family Apiaceae of about 230 species of annuals and perennials with hairless and usually spiny leaves, and dome-shaped umbels of flowers resembling those of thistles. The genus has a cosmopolitan distribution, with the centre of diversity in South America. Some species...
, yellow and bright lavender monkeyflowers
Mimulus
Mimulus is a diverse plant genus, the monkey-flowers and musk-flowers. The about 150 species are currently placed in the family Phrymaceae. The genus has traditionally been placed in Scrophulariaceae. The removal of Mimulus from that family has been supported by studies of chloroplast DNA first...
, star lilies
Common Star Lily
Zigadenus fremontii, known as the common star lily, Frémont's deathcamas or star zigadene, is an attractive wildflower found on grassy or woody slopes, or rocky outcrops, in many lower-lying regions of California, southern Oregon, and northern Baja California. Like other deathcamases, Z...
, yarrow
Yarrow
Achillea millefolium or yarrow is a flowering plant in the family Asteraceae, native to the Northern Hemisphere. In New Mexico and southern Colorado, it is called plumajillo, or "little feather", for the shape of the leaves. In antiquity, yarrow was known as herbal militaris, for its use in...
, and endangered grasses such as Solano grass
Tuctoria mucronata
The grass Tuctoria mucronata, which is known by several common names including Solano grass, Crampton's tuctoria, and prickly spiralgrass, is a federally listed endangered plant species endemic to two counties in northern California. It is a small annual, with stems growing decumbent against the...
.
Because of their characteristics, vernal pools are often threatened by development in the same way that wetlands are.
As a result, most pools have been converted into residential zones, roads, and industrial parks. That is why most extant pools occur on protected or private land such as national park
National park
A national park is a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns. Although individual nations designate their own national parks differently A national park is a reserve of natural, semi-natural, or developed land that a sovereign state declares or...
s, and ranch
Ranch
A ranch is an area of landscape, including various structures, given primarily to the practice of ranching, the practice of raising grazing livestock such as cattle or sheep for meat or wool. The word most often applies to livestock-raising operations in the western United States and Canada, though...
es.
A large number of rare
Rare species
A rare species is a group of organisms that are very uncommon or scarce. This designation may be applied to either a plant or animal taxon, and may be distinct from the term "endangered" or "threatened species" but not "extinct"....
, endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
, and endemic species occur in vernal pool areas. For example, the San Diego mesa mint, a highly endangered plant, is found exclusively in vernal pools in the San Diego
San Diego, California
San Diego is the eighth-largest city in the United States and second-largest city in California. The city is located on the coast of the Pacific Ocean in Southern California, immediately adjacent to the Mexican border. The birthplace of California, San Diego is known for its mild year-round...
area. Another example is the wildflower
Wildflower
A wildflower is a flower that grows wild, meaning it was not intentionally seeded or planted. Yet "wildflower" meadows of a few mixed species are sold in seed packets. The term "wildflower" has been made vague by commercial seedsmen who are interested in selling more flowers or seeds more...
Lasthenia conjugens
Lasthenia conjugens
Lasthenia conjugens, commonly known as Contra Costa goldfields, is an endangered species of wildflower endemic to a limited range within the San Francisco Bay Area of the state of California, USA. Specifically this rare species occurs in Napa, Santa Barbara , Solano, Contra Costa, Santa Clara,...
, which is found in limited parts of the San Francisco Bay Area
San Francisco Bay Area
The San Francisco Bay Area, commonly known as the Bay Area, is a populated region that surrounds the San Francisco and San Pablo estuaries in Northern California. The region encompasses metropolitan areas of San Francisco, Oakland, and San Jose, along with smaller urban and rural areas...
. A third example is the herb Limnanthes vinculans endemic to Sonoma County, California
Sonoma County, California
Sonoma County, located on the northern coast of the U.S. state of California, is the largest and northernmost of the nine San Francisco Bay Area counties. Its population at the 2010 census was 483,878. Its largest city and county seat is Santa Rosa....
.
Fauna
Many of the amphibians that breed only in vernal pools spend most of their lives in the uplands within hundreds of feet of the vernal pool. Eggs are laid in the vernal pool, then the juveniles leave the pool two or three months later, not to return until the following spring to breed. Therefore, the upland areas surrounding a vernal pool are critical for the survival of these species. In New York state the endangered tiger salamanderTiger Salamander
The Tiger Salamander is a species of Mole Salamander. The proper common name is the Eastern Tiger Salamander, to differentiate from other closely related species.-Description:...
(Ambystoma tigrinum) is dependent on vernal pools to breed as described above. A few other obligate vernal pool species are the marbled salamander
Marbled Salamander
The Marbled Salamander is a species of mole salamander found in the eastern United States.- Description :The Marbled Salamander is a stocky, boldly banded salamander. The bands of females tend to be gray, while those of males are more white. Adults can grow to about 11 cm, , a bit small compared...
(Ambystoma opacum), Jefferson's salamander (Ambystoma jeffersonianum), the blue-spotted salamander
Blue-spotted Salamander
The Blue-spotted salamander, or Ambystoma laterale, is a mole salamander native to the Great Lakes states and northeastern United States, and parts of Ontario and Quebec in Canada. Their range is known to extend to James Bay to the north, and southeastern Manitoba to the west.-Description:These...
(Ambystoma laterale) and the
spotted salamander
Spotted Salamander
The Spotted Salamander or Yellow-spotted Salamander is a mole salamander common in the eastern United States and Canada. The Spotted Salamander is the State amphibian of South Carolina. It has recently been found that its embryos have algae living inside them in a mutualistic...
(Ambystoma maculatum).
Some other species, notably the fairy shrimp, lay eggs capable of entering a state of cryptobiosis
Cryptobiosis
Cryptobiosis is an ametabolic state of life entered by an organism in response to adverse environmental conditions such as desiccation, freezing, and oxygen deficiency. In the cryptobiotic state, all metabolic procedures stop, preventing reproduction, development, and repair...
. They hatch when rains replenish the water of the pool.
See also
- BogBogA bog, quagmire or mire is a wetland that accumulates acidic peat, a deposit of dead plant material—often mosses or, in Arctic climates, lichens....
- California native plantsCalifornia native plantsCalifornia native plants are plants that existed in California prior to the arrival of European explorers and colonists in the late 18th century...
- Riparian zoneRiparian zoneA riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the fifteen terrestrial biomes of the earth. Plant habitats and communities along the river margins and banks are called riparian vegetation, characterized by...
- SwampSwampA swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...
- WetlandWetlandA wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....