Fourspine sticklebacks (Apeltes quadracus) inhabit coastal areas of North America, from the Gulf of St. Lawrence south to the Trent River drainage in North Carolina. This species is particularly abundant along the coast of New York. A few populations have been observed upstream in the Hudson, Delaware and Susquehanna drainages. One lake in Maine was found to contain A. quadracus in low abundance, as well as several lakes and streams in Nova Scotia. This species has been introduced by humans into Lake Superior, the Great Swamp in New Jersey and the Avalon Peninsula, Newfoundland. (Briggs and Waldman, 2002; NatureServe, 2013; Scott and Crossman, 1973; Stephenson and Momot, 2000; Whittier, et al., 2001)
Fourspine sticklebacks primarily live in marine waters or estuaries, however they are sometimes found in freshwater lakes. Spawning typically takes place in shallow areas of streams and rivers. This species lives primarily in shallow waters (1 to 35 cm). Apeltes quadracus can be found at mid-depth waters (36 to 70 cm), but not at depths greater than 70 cm. Fourspine sticklebacks prefer vegetated waters, having a higher abundance in marine and estuary habitats containing eel grass. In freshwater habitats, A. quadracus is most commonly found in areas containing Elodea (waterweed). (Baker, 1971; Ruiz, et al., 1993; Szedlmayer and Able, 1996; Whittier, et al., 2001)
The body of A. quadracus shows moderate lateral compression and there is a slight projection of the lower jaw, making a small snout. Their skin is considered “naked”, lacking scales or ossified plates. Adults are olive-green to brownish olive in color with dark spots on their side and a silver belly. Four isolated spines are located anterior to the dorsal ray, the second two being approximately half the size of the first two. The presence of four dorsal spines differentiates this species from other sticklebacks. During spawning season, the pelvic spine and membrane of males becomes red.
Adults range in length from 51-64 mm (Scott and Crossman, 1973)
Eggs are approximately 1.5 mm in diameter and amber colored. Hatching occurs approximately six days after spawning, with optimal temperatures being 21 to 22ºC. After hatching, larvae are 4.2 to 4.5 mm in length and dark brown in color. This is followed by a rapid growth period and by day three larvae will reach a length of 6.2 to 6.5 mm. (Rowland, 1974; Scott and Crossman, 1973)
During the mating season, males develop territories and defend their area by extending their pelvic fins and engaging in head-on attack if necessary. After territory establishment, the male goes through a nest-building phase in which aquatic plant material is collected and “glued” together using a secretion that comes from the vent. As a female approaches, a prod-dance-lead courtship behavior will begin. The male will extend his pelvic fin, swim toward the female and prod her with his snout several times. This is followed by spiral movements toward the nest, a waiting period for the female to follow and then repetition until the nest has been reached. After spawning and fertilization, the male continues to defend his territory, even against the female. He will interruption is protection to occasionally “fan” the nest with his fins, and to build another layer where another clutch of eggs can be laid. This process of layered nest building allows the male to collect as many as four or five clutches of eggs. (Rowland, 1974; Scott and Crossman, 1973)
The major breeding season for A. quadracus is in May and June but spawning can occur through the end of July. Males and females migrate to shallow, freshwater systems for reproduction. Females will lay one cluster of 20 to 50 eggs, followed by external fertilization by the male. Sexual maturity is normally reached after one year of development. (Craig and FitzGerald, 1982; Rowland, 1974; Scott and Crossman, 1973)
Males are considered to be in the parental phase when fanning increases. Fanning allows A. quadracus to ventilate each clutch of eggs, alternating between levels in intervals. Between fanning periods, males continue to protect the nest. Little to no attention is given young after they hatch and leave the nest. Females are not known to play a role in parental care. (Rowland, 1974)
The life span of A. quadracus is two to three years in the wild. (Craig and FitzGerald, 1982)
Fourspine sticklebacks migrate seasonally for reproduction. Territory size during breeding is variable depending on the quantity and average size of A. quadracus in an area, however their territory must be large enough to acquire vegetation and build a nest (average nest size is 10 to 20 cm in length). These fish are known to swim in sub-populations in which fish associate with similar individuals based on olfactory and habitat cues. Fourspine sticklebacks have a high tolerance for salinity and consume a wide variety of organisms, allowing them to survive in many different habitats. (Delbeek and Williams, 1988; Nelson, 1968; Scott and Crossman, 1973; Ward, et al., 2004)
There is no known documented home range for fourspine sticklebacks.
There is little literature on perception in fourspine sticklebacks. Sticklebacks (Gasterosteidae) in general typically use chemical cues for predator detection and social interactions. Courtship includes visual and tactile signals. Threespine sticklebacks (Gasterosteus aculeatus), a closely related species, use visual cues when choosing a mate, showing a preference for contrasting colors and intense reds. The coloration of males in A. quadracus> suggests similar behavior on this species. (Ab Ghani, et al., 2016; Boulcott, et al., 2005; McDonald, et al., 1995; Ward, et al., 2004)
The diet of A. quadracus typically consists of planktonic plants and animals. Small invertebrates such as aquatic worms, midges, and copepods are commonly found in their gut. Factors such as aquatic vegetation density and predation can shift their dietary habits. Individuals from habitats with dense vegetation consume more prey than those from poorly vegetated habitats. In the presence of predation, these fish show an increase in benthic prey consumption. (Delbeek and Williams, 1988; Scott and Crossman, 1973)
Known predators of A. quadracus includes American eels (Anguilla rostrate), killfish (Fundulus), and Atlantic tomcod (Microgadus tomcod). Sticklebacks (Gasterosteidae) avoid predation through camouflage. Their silver bellies help them to go undetected from below and from above, they look like a small stick. (Delbeek and Williams, 1988; Greenbank and Nelson, 1959)
Planktivores serve an important role in the aquatic food web because of their flexibility in diet, habitat, and range of prey size. They are also an important food source for larger fish. Fourspine sticklebacks are known to be hosts to a number of parasites, including monogenetic trematodes (Gyrodactylus avalonia, Gyrodactylus cameroni and Gyrodactylus canadensis), digenetic trematodes (Podocotyle atomon), cestodes (Proteocephalus) and a nematode (Cystidicola farionis). Invasion of A. quadracus into Lake Superior negatively affects native fish populations due to habitat and food competition. (Scott and Scott, 1988; Sommer, 2012; Stephenson and Momot, 2000)
Fourspine sticklebacks are used for bait and purchased for aquariums. In Europe, sticklebacks (Gasterosteidae) are used in small quantities to make fish oil and meal. Occasionally, they are also used in dog food and consumed by humans. (Greenbank and Nelson, 1959; Scott and Crossman, 1973)
There are no known adverse economic effects of A. quadracus.
Fourspine sticklebacks have no known threats and currently are categorized as having low conservation concern. (NatureServe, 2013)
Cecelia Smith (author), Indiana University - Purdue University Fort Wayne, Mark Jordan (editor), Indiana University-Purdue University Fort Wayne, George Hammond (editor), Animal Diversity Web Staff.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
areas with salty water, usually in coastal marshes and estuaries.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
fertilization takes place outside the female's body
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
mainly lives in water that is not salty.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
parental care is carried out by males
makes seasonal movements between breeding and wintering grounds
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
the business of buying and selling animals for people to keep in their homes as pets.
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
an animal that mainly eats plankton
having more than one female as a mate at one time
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
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