Endangered, Extinct, or Extirpated Species Flashcards
Invertebrate
American Burying Beetle (aka Carrion Beetle)
Nicrophorus americanus (Extirpated)
It belongs to the order Coleoptera and the family Silphidae
During the winter months when temperatures are below 15 °C (60 °F) adults bury themselves in the soil to overwinter.
When temperatures are above 15 °C (60 °F) they emerge from the soil and begin the mating and reproduction process.
Both the male and female take part in raising the young.
Male burying beetles often locate carcasses first and then attract a mate. Beetles often fight over the carcass, with usually the largest male and female individuals winning.
The victors bury the carcass, the pair mates, and the female lays her eggs in an adjacent tunnel.
Within a few days, the larvae develop and both parents feed and tend their young.
Brood size ranges from one to 30 young, but 12 to 15 is the average size.
The larvae spend about a week feeding off of the carcass then crawl into the soil to pupate, or develop. Mature beetles emerge from the soil 45 to 60 days after their parents initially bury the carcass.
Adult American burying beetles live for only 12 months.
Invertebrate
Chittenango Ovate Amber Snail
Novisuccinea chittenangoensis
Terrestrial snail with a life span of about two and a half years.
It is hermaphroditic and mates from April until June. 4-15 transparent, jelly-like eggs are laid about a month after mating. The young snails hatch in 2-3 weeks, measuring .04 inch (1 mm).
They feed on microscopic algae and other species of microflora that grow on the rocks and vegetation in the spray zone of the waterfall around which they live.
They ingest a lot of calcium carbonate for shell development.
Adapted to relatively constant environmental and climatic conditions, including a clean water supply, the snail is intolerant of sudden changes.
Invertebrate
Dwarf Wedgemussel
Alasmidonta heterodon
Freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels.
Found in small creeks to deep rivers in stable habitats with substrates ranging from mixed sand, pebble and gravel, to clay, silt sand, cobble, or embedded in clay banks in water depths of a few inches to greater than 20 feet .
In the southern portion of its range, it is often found buried under logs or root mats in shallow water.
Two lateral teeth on the right valve and only one on the left side.
Its reproductive cycle requirs a host fish on which its larvae (glochidia) parasitize and metamorphose into juvenile mussels.
Life expectancy is estimated at 10 to 12 years (Michaelson and Neves 1995).
The dwarf wedgemussel is considered to be a long-term brooder. In general, dwarf wedgemussel glochidia may be released between March and June, with peak release times varying from south to north.
Reproductive output appears to be correlated with local population abundance.
Invertebrate
Karner Blue Butterfly
Lycaeides melissa samuelis
Although Karner blue butterflies are characteristic of oak savannas and pine barrens, they also occur in frequently disturbed areas such as rights-of-way, old fields, and road margins.
Shade-grown wild lupine has been shown to provide higher quality larval resource than sun-grown lupine.
Flight typically begins at 76 °F (24.6 °C) for females and 80 °F (26.4 °C) for males.
Signs of heat stress started at 96 °F (35.6 °C) for females and 98 °F (36.8 °C) for males.
Karner blue butterflies are dependant on heterogeneous habitat for the varied requirements of different broods, sexes, and life stages over a wide range of environmental conditions.
Karner blue butterflies have 2 broods per year, following wild lupine phenology. Eggs laid by Karner blue butterflies in late summer overwinter and hatch in mid- to late April. Development from egg through four larval instars and pupation takes from 25 to 60 days. The average lifespan of adult Karner blue butterflies has been reported at between 3 and 5 days.
The first Karner blue butterfly flight generally occurs sometime between mid-May and mid-June, with males typically appearing earlier than females.
First flight females lay the vast majority of their eggs on wild lupine. These eggs develop into the adults of the second Karner blue butterfly flight, which generally occurs in July and August. Although always near a wild lupine plant, second brood females lay more eggs on grasses, other plants, and litter than 1st brood females. The 2nd flight is typically two to four times the size of the first flight. However, the first flight of Karner blue butterflies can be larger than the second.
Wild caught Karner blue butterfly females have been observed to lay from 7.7 to 83 eggs on average.
Karner blue butterflies do not typically move vary far, with males usually moving further than females, with most studies showing average distances moved by individual butterflies of well under 1,000 feet (300 m).
Karner blue butterfly larvae benefit from a facultative, mutualistic relationship with several ant species.
Invertebrate
Anoplophora glabripennis
Asian Longhorned Beetle (Asian Cerambycid Beetle)
Believed to have arrived in New York City in the 1980s in wood packing material, the center of the infection zone was a warehouse which imported plumbing supplies from China.
The government is trying to eradicate this species because if it becomes established it could significantly impact natural forests and urban environment, with an estimated death toll of 1.2 billion trees if it spread nationwide. It is believed that eradication efforts can be successful.
The steps that have been taken to eliminate the ALB include:
Quarantines, Infested trees cut, chipped and burned, Insecticide treatments, Extensive surveys, Shipping restrictions.
Asian long-horned beetles are detrimental to any ecosystem they inhabit. These beetles have the ability to significantly alter the composition of North American hardwood forests. It is estimated that nearly 1/3 of all trees would have to be destroyed in the United States if they were to spread throughout the country.
Beetles are 0.75- 1.50 in long (not including antennae), shiny black with bright white spots and blue tinted legs. Each adult has a pair of curved, black-and-white striped antennae that are longer than the body. Adults emerge from trees during May, June, and July and can live for up to 66 days. They feed on plant shoots for a few days then mate. After mating, females chew rough, oval pits in the bark of host trees, where they lay eggs. When the eggs hatch, the white grub-like larvae bore into the wood. Larvae mature inside the tree until they become adults and chew round, 3/8 inch (dime-sized) exit holes in trunks and branches, from which they emerge. This life cycle produces new adults every year, rather than every 2-4 years like most other longhorned beetles. Although ALB can fly up to 400 yards, they typically do not leave their host tree. In China, studies show that infestations generally spread less than 1000 ft/year.
Invertebrate
Emerald Ash Borer
Agrilus planipennis
The adult beetle is about 8.5 mm(0.33 in) long and 1.6 mm (1⁄16 in) wide. Adults begin to emerge from the trunks of ash trees after the accumulation of 400-500 growing degree days base 50°F (GDD). After emergence, adults fly into the ash canopy where they feed on leaves throughout their lives. EAB adults start mating one week after emergence, and females begin laying eggs 2–3 weeks later. A female EAB may lay >100 eggs in her lifetime, depositing them individually or in groups on the bark along the trunk and portions of the major branches. Eggs are laid in areas where the bark is rough, and between bark layers or in bark crevices. Eggs are approximately 1.0 mm long x 0.6 mm wide and creamy white when laid; fertile eggs gradually turn amber after a few days. The eggs hatch after about two weeks. Newly hatched larvae bore through the bark to the phloem and outer layer of new sapwood where they feed until the weather gets too cold in the fall. There are four stages of larval development (instars). As they feed, the larvae create long serpentine galleries filled with frass, which enlarge in width as they grow. When fully mature, fourth-instar larvae are 26 to 32 mm long. Their head is mostly retracted into the prothorax with only the dark brown mouthparts visible. The prothorax is enlarged, with the mesothorax and metathorax more narrow. Larvae have 10 bell-shaped abdominal segments and a pair of small brown structures called urogomphi, which are characteristic of all larvae in the genus Agrilus. Overwintering larvae, pre-pupae, pupae, and adults In the fall, mature fourth-instar EAB larvae excavate pupal chambers in the sapwood or outer bark where they fold into overwintering “J-shaped larvae”. In the spring, the J-shaped larvae shorten into prepupae then shed their cuticle to become naked pupae. Pupae are initially creamy white, but the eyes turn red and the body begins to darken as they develop. To emerge from ash trees, adults chew D-shaped exit holes through the bark and are capable of immediate flight upon emergence. EAB larvae that are immature as cold weather arrives in the fall will simply overwinter in their larval gallery.
Invertebrate
Hemlock Woolly Adelgid
Adelges tsugae
DNA evidence suggests that the invasive eastern U.S. population came from Japan and not the western United States, where the species feeds on western hemlock.
Hemlock woolly adelgids are small in size and to the naked eye only their woolly coverings are easily visible. The insect has 2 generations per year and growth occurs from fall through late spring. Insects in summer are inactive and scarcely visible at the bases of needles as black dots. Woolly masses develop in October and are present thereafter through June of the following year.
In the eastern USA, hemlock woolly adelgid is killing eastern and Carolina hemlocks in large numbers.
A biological control program is in progress against this pest, based on specialized predatory beetles that feed only on adelgids, collected in western North America (Laricobius nigrinus Fender) or China/Japan (species of Laricobius and various Scymnus ladybird beetles).
The primary host is hemlock, with spruce being a possible secondary (alternative) host. The hemlock woolly adelgid (HWA), a destructive aphid-like insect pest of eastern and Carolina hemlock, is originally from Asia.
HWA feeds on all ages of trees. The insects attach themselves to the base of the hemlock needles and feed from the new twig growth with piercing sucking mouthparts. The first symptoms are needle yellowing and needle drop, followed by branch desiccation (drying) and a lack of vigor indicated by a thinning crown. Limb dieback may occur within two years of the initial infestation on seedlings and saplings. Heavily infested larger trees usually die within four years, although it may take longer than 10 years depending on proximity to other infested trees, tree size, the level of environmental stress and the quality of the growing site. When not at serious risk to the tree, presence of the dirty white globular masses of woolly puffs attached to the twigs or base of needles reduces the value of ornamentals.
These small insects display several different forms during their life history, including winged and wingless forms. Eggs are initially brownish-orange, but will darken as the eggs mature. Crawler stage nymphs produce white cottony/waxy tufts which cover their bodies and remain in place throughout their lifetime. Generally, they are brownish-reddish in color, oval in shape, and about 0.8 mm in length. The adults are small (1/32 inch), oval and reddish purple, although covered with white, waxy tufts. This waxy material is produced from pores on their bodies. The white masses are 3 mm or more in diameter. The presence of these masses on the bark, foliage, and twigs of hemlock is a sure sign of hemlock woolly adelgid.
The HWA are all female and they overwinter within the waxy mass. In December through March, the adult adelgids lay egg sacs of up to 300 eggs each. After hatching in April-May, the flat reddish-brown crawlers without the protective covering actively seek a suitable site on the host plant to feed. After settling, this first generation molts and the nymphs become black with a white wax fringe around the edge and down the center of the back. The nymphs feed on twigs, usually near the base of needles. They soon extrude the white, fluffy “wool” that covers their bodies. About half of the resulting adults have two pairs of wings and will fly off in search of an alternate host of spruce on which to feed. Because no suitable spruce host occurs in North America, the adelgids will eventually die of starvation. The other half are wingless and remain on the tree, where they lay eggs in a fluffy mass on the hemlock.
The second-generation crawlers emerge from the egg masses of up to 250 eggs each. The crawlers are dispersed via wind, birds and other animals. They move to the new growth and settle at the base of the needles to feed and molt into black nymphs with characteristic white fringes. These nymphs will remain at this site until maturity. The nymphs enter a period of dormancy in late summer before resuming feeding in the fall. In October or November, they molt and their bodies will begin to be covered with the white, cottony wax. Gradually maturing to adults by feeding throughout the fall and winter, these adults begin the yearly cycle again by laying eggs in April. Two adelgid generations per year allow for rapid buildup of this pest.
Control: Insecticidal soap, Horticultural oil, Imidacloprid
Management of HWA by an imported predaceous lady beetle, Pseudoscymnus tsugae, is most effective using an IPM approach for forest stands that includes chemical control.
Invertebrate
Zebra Mussel
Dreissena polymorpha
Size: < 50 mm
Native Range: The zebra mussels is native to the Black, Caspian, and Azov Seas. In 1769, Pallas first described populations of this species from the Caspian Sea and Ural River.
Zebra mussels were first discovered in North America in 1988 in the Great Lakes. The first account of an established population came from Canadian waters of Lake St. Clair, a water body connecting Lake Huron and Lake Erie. By 1990, zebra mussels had been found in all the Great Lakes. The following year, zebra mussels escaped the Great Lakes basin and found their way into the Illinois and Hudson rivers.
Under natural thermal regimes, zebra mussel oogenesis occurs in autumn, with eggs developing until release and fertilization in spring. In thermally polluted areas, reproduction can occur continually through the year. Females generally reproduce in their second year. Eggs are expelled by the females and fertilized outside the body by the males; this process usually occurs in the spring or summer, depending on water temperature. Optimal temperature for spawning is 14–16°C. Over 40,000 eggs can be laid in a reproductive cycle and up to one million in a spawning season. Spawning may last longer in waters that are warm throughout the year. After the eggs are fertilized, the larvae (veligers) emerge within 3 to 5 days and are free-swimming for up to a month. Optimal temperature for larval development is 20–22°C. Dispersal of larvae is normally passive by being carried downstream with the flow. The larvae begin their juvenile stage by settling to the bottom where they crawl about on the bottom by means of a foot, searching for suitable substratum. They then attach themselves to it by means of a byssus, an “organ” outside the body near the foot consisting of many threads. Although the juveniles prefer a hard or rocky substrate, they have been known to attach to vegetation. As adults, they have a difficult time staying attached when water velocities exceed 2 m/s.
Zebra mussels are filter feeders having both inhalant and exhalant siphons. They are capable of filtering about one liter of water per day while feeding primarily on algae. Once the veliger undergoes morphological changes including development of the siphon, foot, organ systems and blood, it is known as a postveliger. Further subdivision of the larval stage has been delineated: (veliger) preshell, straight-hinged, umbonal, (postveliger) pediveliger, plantigrade, and (juvenile) settling stage (ZMIS 1996). The settling stage attaches to a substrate via protienaceous threads secreted from the byssal gland. The vast majority of veliger mortality (99%) occurs at this stage due to settlement onto unsuitable substrates. Sensitivity to changes in temperature and oxygen are also greatest at this stage. Once attached, the life span of D. polymorpha is variable, but can range from 3–9 years. Maximum growth rates can reach 0.5 mm/day and 1.5–2.0 cm/year. Adults are sexually mature at 8–9 mm in shell length (i.e. within one year).
Zebra mussels attach to any stable substrate in the water column or benthos: rock, macrophytes, artificial surfaces (cement, steel, rope, etc.), crayfish, unionid clams, and each other, forming dense colonies called druses. Long-term stability of substrate affects population density and age distributions on those substrates. Within Polish lakes, perennial plants maintained larger populations than did annuals (Stanczykowska and Lewandowski 1993). Populations on plants also were dominated by mussels less than a year old, as compared with benthic populations. These populations of small individuals allow higher densities on plants. In areas where hard substrates are lacking, such as a mud or sand, zebra mussels cluster on any hard surface available. Given a choice of hard substrates, zebra mussels do not show a preference, indicating that veligers cannot discriminate between substrates (with the exception of substrate rejection due to contaminants). Research on Danish lakes shows that factors exist, however, that cause substrate to be unsuitable for both initial and long term colonization: extensive siltation, some sessile benthic macroinvertebrates, macroalgae, and fluctuating water levels exposing mussels to desiccation (Smit et al. 1993). The dispersion of zebra mussels within a lake is controlled by physical conditions including wind strength, lake/shore morphometry, and current patterns (Stanczykowska and Lewandowski 1993). These conditions affect both spatial patterns of pelagic veliger density and benthic adult dispersion. Population density of benthic adults has been observed to vary as widely as two orders of magnitude (e.g., <100 to >1500 individuals/m2) within individual Polish lakes due to these physical conditions. Tolerance limits of physical and chemical parameters are well known (Sprung 1993, Vinogradov et al. 1993, McMahon 1996).
North American populations are generally adapted to warmer temperature regimes than their European counterparts. Eggs are released when the environmental temperature reaches 13°C and release rate is maximized over 17°C. The optimal temperature range for adults extends to 20–25°C, but D. polymorpha can persist in temperatures up to 30°C. Short term tolerance of temperatures up to 35°C is possible if the mussels were previously acclimated to high temperatures. Rapid warming of shallow lakes has been hypothesized to detrimentally affect reproductive rates in Danish populations. Oxygen demands are similar to those of other freshwater bivalves including unionids. Tolerance of “anaerobic” conditions has been reported for short time periods under certain temperatures and sizes, but zebra mussels cannot persist in hypoxic conditions. The lower limit of pO2 tolerance is 32–40 Torr at 25°C. Zebra mussels have been found in the hypolimnetic zone of lakes with oxygen levels of 0.1-11.2 mg/l, and in the epilimnetic zone with oxygen levels of 4.2–13.3 mg/l. Zebra mussels are described as poor O2 regulators, possibly explaining their low success rate in colonizing eutrophic lakes and the hypolimnion. Zebra mussels can tolerate only slight salinity.
Although some populations of European zebra mussels can be found in estuaries, their persistence has been speculatively attributed to reduced tidal fluctuation.
Zebra mussels can reduce filtration rates (more frequent interruption of filtering or slower pumping rates) and/or produce pseudofeces above an incipient limiting concentration (ILC) of algae to maintain a constant consumption rate. Feeding activity can be described by the clearance rate (percentage of algal biomass removed from the water column over time), biomass of cleared algae (BCA), feces production and pseudofeces production (µg F or P/BCA).
Its rapid dispersal throughout the Great Lakes and major river systems was due to the passive drifting of the larval stage (the free-floating or “pelagic” veliger), and its ability to attach to boats navigating these lakes and rivers. Under cool, humid conditions, zebra mussels can stay alive for several days out of water.
Zebra mussels are notorious for their biofouling capabilities by colonizing water supply pipes of hydroelectric and nuclear power plants, public water supply plants, and industrial facilities. They colonize pipes constricting flow, therefore reducing the intake in heat exchangers, condensers, fire fighting equipment, and air conditioning and cooling systems. Zebra mussel densities were as high as 700,000/m2 at one power plant in Michigan and the diameters of pipes have been reduced by two-thirds at water treatment facilities. Navigational and recreational boating can be affected by increased drag due to attached mussels. Small mussels can get into engine cooling systems causing overheating and damage. Navigational buoys have been sunk under the weight of attached zebra mussels. Fishing gear can be fouled if left in the water for long periods. Deterioration of dock pilings has increased when they are encrusted with zebra mussels. Continued attachment of zebra mussel can cause corrosion of steel and concrete affecting its structural integrity.
Zebra mussels can have profound effects on the ecosystems they invade. They primarily consume phytoplankton, but other suspended material is filtered from the water column including bacteria, protozoans, zebra mussel veligers, other microzooplankton and silt. Increased water clarity allows light to penetrate further, potentially promoting macrophyte populations. Zebra mussels are able to filter particles smaller than 1µm in diameter, although they preferentially select larger particles.
Clearance rates were constant over varying concentrations of pure cultures of Chlamydomonas reinhardtii, a spherical unicellular species of 7.42 µm (± 0.13µm) in diameter. This indicates that the concentrations used in experiments were below the ILC. However, clearance rates decreased, with increasing concentrations of Pandorina morum, a species made up of colonies with varying numbers of cells that are individually as large as C. reinhardtii. This indicates that the concentrations used in experiments were above the ILC. Large zebra mussels (20-25 mm in length) displayed a higher clearance rate across all concentrations of C. reinhardtii than did small mussels (10-15 mm). Incipient limiting concentration differed in this study from previous studies done with European populations. Thus zebra mussel size, phytoplankton species, and regional population differences affect clearance rates, ILC and feces/pseudofeces production. Zebra mussels produce pseudofeces to avoid ingesting non-food material (e.g. clay), as a mechanism to deal with overabundance of food (e.g. algal concentrations above the ILC), and possibly as a way to reject unpalatable algae. Zebra mussels readily reject blue-green algae, such as Microcystis, as pseudofeces (Vanderploeg et al. 2001). The presence of this cyanobacterium does not inhibit filtering, except in mass abundances such as a bloom (Noordhuis et al. 1992, Lavrentyev et al. 1995). Zebra mussels can select material for rejection through pseudofeces production internally, perhaps identifying cyanobacteria by chemical cues (ten Winkel and Davids 1982). Inland lakes with lower nutrient levels have been observed to be more frequently dominated by Microcystis when invaded by zebra mussels (Raikow et al. 2004). Understanding of the fate of pseudofeces once it expelled is poor. Zebra mussels removed metals from the water column of Lake Erie and deposited it to the bottom at high rates (Klerks et al. 1996). Roditi et al. (1997) found that the biodeposits of zebra mussel were organically enriched, including 3.9% live algae by weight. Resuspension of this material occurred in their system, a tidal estuary, reducing the potential impact of biodeposition to the benthos. Less well known is the fate of live algae bound into pseudofeces. Bastviken et al. (1998) speculate that phytoplankton which survives the pseudofeces process must be resuspended in order for long term survival, a process less likely to occur in inland lakes than in tidal estuaries. If survivorship following filtration is equal between phytoplankton species, then community species composition can remain unchanged. Other factors may affect the phytoplankton community, however, including increased light.
The zooplankton community has also been affected by the invasion of zebra mussels. Zooplankton abundance dropped 55-71% following mussel invasion in Lake Erie, with microzooplankton more heavily impacted (MacIsaac et al. 1995). Mean summer biomass of zooplankton decreased from 130 to 78 mg dry wt. m-3 between 1991 and 1992 in the inner portion of Saginaw Bay. The total biomass of zooplankton in the Hudson River declined 70% following mussel invasion, due both to a reduction in large zooplankton body size and reduction in microzooplankton abundance. These effects can be attributed to reduction of available food (phytoplankton) and direct predation on microzooplankton. Increased competition in the zooplankton community for newly limited food should result from zebra mussel infestation. The size of individual zooplankters might decrease. Hypotheses can be formulated specifying which species will prevail based on knowledge of competitive ability.
Effects may continue through the food web to fish. Reductions in zooplankton biomass may cause increased competition, decreased survival and decreased biomass of planktivorous fish. Alternatively, because microzooplankton are more heavily impacted by zebra mussels the larval fish population may be more greatly affected than later life stages. This may be especially important to inland lakes with populations of pelagic larval fish such as bluegills. Benthic feeding fish may benefit as opposed to planktivorous fish, or behavioral shifts from pelagic to benthic-feeding may occur. In addition, proliferation of macrophytes may alter fish habitat. Experimental evidence exists that zebra mussels can reduce the growth rate of larval fish through food web interactions (Raikow 2004). Conclusive negative impacts on natural populations of fish, however, have yet to observed (see Raikow 2004). Other effects include the extirpation of native unionid clams through epizootic colonization (Schloesser et al. 1996, Baker and Hornbach 1997). Zebra mussels restrict valve operation, cause shell deformity, smother siphons, compete for food, impair movement and deposit metabolic waste onto unionid clams. Survival rates of native unionid mussels in the Mississippi River, Minnesota have been shown to decline significantly with the increase in zebra mussel colonization (Hart et al. 2001).To date, unionids have been extirpated from Lake St. Clair and nearly so in western Lake Erie. Many species of birds known to be predators of zebra mussels occur in the Great Lakes region. While a new food source may benefit such predators, biomagnification of toxins into both fish and birds is possible. Some effects have been hypothesized as worst-case scenarios. For example, zebra mussels may cause a shift from pelagically to benthically-based food webs in inland lakes. Zebra mussels may also shift lakes from a turbid and phytoplankton-dominated state to clear and macrophyte-dominated state, i.e. between alternative stable equilibria (Scheffer et al. 1993).
Management: Control: There are many methods that have been investigated to help control zebra mussels. They are listed below in no particular order. Some methods will work better than others in a particular situation.
Chemical Molluscicides: Oxidizing (chlorine, chlorine dioxide) and Non-oxidizing
Manual Removal (pigging, high pressure wash)
Dewatering/Desiccation (freezing, heated air)
Thermal (steam injection, hot water 32oC)
Acoustical Vibration
Electrical Current
Filters, Screens
Coatings: Toxic (copper, zinc) and Non-toxic (silicone-based)
Toxic Constructed Piping (copper, brass, galvanized metals)
CO2 Injection
Ultraviolet Light
Anoxia/Hypoxia
Flushing
Biological (predators, parasites, diseases)
Fish
Shortnose Sturgeon (pinkster, salmon sturgeon, lake sturgeon )
Acipenser brevirostrum
Weight: up to 50 pounds (23 kg)
Length: up to 4.5 feet (1.4 m)
Small North American sturgeon found in 16 -19 large rivers & estuary systems along the Atlantic seaboard from the St. John River in New Brunswick, Canada, to the St. Johns River in Florida. Populations may be disjunct.
The species is sometimes mistaken for juvenile Atlantic sturgeon, as adults of this species are similar in size to juveniles of that species.
They spawn in fresh water, above the head of the tide, in moving water over rubble or gravel bottoms with little silt or organic material. Time of spawning varies by latitude and is likely based on water temperatures in the range from 9-12 degrees Celsius although successful spawning can occur from 6.5-15 degrees Celsius. Other spawning requirements include a day length of 13.9-14.9 hours, and water velocity at the bottom of 30-120 centimeters per second. Eggs hatch after 13 days, into 7–11 mm long hatclings with a large yolk-sac, minimal sight, minimal swimming ability and a strong tendency to seek cover. After another 9–12 days they mature to a swimming larval stage at about 15 mm in length, resembling a miniature adult by the time they reach 20mm in length and begin feeding. They then drift downstream in the deep channels of the river, remaining in fresh water for the first year of their life. Juveniles, up to 18 inches long, generally move to the area where fresh and salt water come together, and move with it through the tidal cycle.
Adults can be found in either fresh or salt water. Adults mature sexually at 45 to 55 cm (18 to 22 in) in length, at an age varying with latitude. Males mature after 2–3 years in Georgia or 10–14 years in New Brunswick, and females mature between 6 and 17 years of age (again, earlier in southern rivers). First spawning occurs after sexual maturity; 1–2 years later for males and up to 5 years later for females. Adults continue to grow to between 3 and 4 feet in length. A male may breed every year or every other year, and seldom lives beyond age 30. Females usually breed every third to fifth year, laying between 40,000 and 200,000 eggs in those years that they breed, and can live to age 67. Females spend multiple years with reduced feeding and growth while they are producing the gonadal material needed for spawning.
The maximum salinity in which the species has been found is 30-31 ppt, slightly below the salinity of sea water. In the Connecticut River in Massachusetts, the Santee River in South Carolina, and the Saint John River in New Brunswick, the shortnose sturgeon was able to survive as a landlocked population following construction of river dams. This indicates that the species does not require salt water in its life cycle. Hatchery-raised sturgeon appear to do best in zero-salinity fresh water. Northern populations generally spend more time in salt water than southern populations do, to the extent of being anadromous instead of amphidromous.
Sturgeon are bottom feeders eating primarily insects and small crustaceans. Juveniles have been observed with stomach contents with as much as 90% non-food items leading to a belief that they randomly vacuum the bottom. Adults in fresh water primarily eat mollusks, supplemented by polychaetes and small benthic fish in estuaries or crustaceans and insects in fresh water.
The largest population, estimated to be at least 60,000 adults in 2007, is found in the Hudson River. The second largest, 18,000 adults and roughly 100,000 of all ages, is in the Saint John River.
Little non-human predation is documented. Yellow perch have been caught with the current year’s young in their stomach, and it is believed that sharks and seals may occasionally eat adults. Parasites are not believed to be harmful. There are no reported incidents of diseases among wild shortnosed sturgeon, although one hatchery population has suffered a disease outbreak.
Genetically, shortnose sturgeons are 16-ploid, having chromosones in groups of 16, rather than the pairs that most vertebrates have. It may have been one of the last sturgeon species to evolve.
Amphibians
Northern Cricket Frog
Acris crepitans
Species of small Hylid frog native to US & NE Mexico. Despite being members of the tree frog family, they are not arboreal. There are three subspecies
One of North America’s two smallest vertebrates, from 0.75 to 1.5 in (19–38 mm) long. Its dorsal coloration varies widely, and includes greys, greens and browns, often in irregular blotching patterns. Typically there is dark banding on the legs and a white bar from the eye to the base of the foreleg. The skin has a bumpy texture. Northern Cricket Frogs have been observed with snouts indistinguishable from those of the Southern species. Biologists have recorded northern cricket frogs in the northern fringes of their range with extremely sharp posterior leg stripes.
Diurnal and generally active much of the year, except in mid-winter in northern areas when the water is frozen. Their primary diet is small 0.5 inches to 1.5 inches long insects, including mosquitos. They in turn are predated upon by a number of species, including birds, fish, and other frogs. To escape predators, they are capable of leaping up to 6 ft (almost 2 m) in a single jump and are excellent swimmers.
Breeding generally occurs from May -July. The males call from emergent vegetation with a high pitched, short, pebble-like call which is repeated at an increasing rate. The sound suggests pebbles being clicked together, much like a cricket, hence the name. One egg is laid at a time and generally attached to a piece of vegetation. The 0.5 inch (14 mm) tadpoles hatch in only a few days and undergo metamorphosis in early fall. Maturity is usually reached in less than a year.
Cricket frogs prefer the edges of slow moving, permanent bodies of water. Large groups of them can often be found together along the muddy banks of shallow streams, esp. during premigratory clustering. The northern cricket frog has been observed to hibernate upland, often at considerable distance from water.
Subspecies:
Blanchard’s cricket frog, Acris crepitans blanchardi Eastern cricket frog, Acris crepitans crepitans
Coastal cricket frog, Acris crepitans paludicola
Amphibians
Tiger Salamander
Ambyostoma tigrinum
