The spotted sunfish ( Lepomis punctatus), also known as a stumpknocker, is a member of the freshwater sunfish family Centrarchidae and order Centrarchiformes. The redspotted sunfish, redear sunfish and pumpkinseed sunfish are its closest relatives. Lepomis punctatus is olive-green to brown in color with black to reddish spots at the base of each scale that form rows of dots on the side. The scientific name punctatus refers to this spotted pattern. It was first described in 1831 by Valenciennes.
The spotted sunfish is a warmwater native of the Southeastern United States that inhabits areas of slow moving water. It is a benthic insectivore. Spotted sunfish do not commonly exceed 10 cm and a weight of 3 oz. It has some value as a pan fish and is occasionally caught by bream anglers. Spotted sunfish exhibit similar breeding behavior to other sunfishes. A single male guards a nest with multiple females. It is evaluated by the IUCN as a Least concern species and shows little danger of decline or high sensitivity to habitat changes. It has been suggested that it could be used as an indicator species, making it valuable to stream management. The spotted sunfish is a habitat generalist, but prefers complex habitats. It has not been established as an invasive species in other parts of the world.
Originally Lepomis punctatus and Lepomis miniatus were both classified as the same species Lepomis punctatus. Morphological differences and molecular evidence supported a significant difference in the eastern and western species of Lepomis punctatus. The species was divided into subspecies Lepomis punctatus punctatus in the east and Lepomis punctatus miniatus in the west. Later (1992) miniatus was elevated into its own species.Warren, M.L. Variation of the spotted sunfish, Lepomis punctatus complex (Centrarchidae): morphometrics, pigmentation and species limits. Bulletin- Alabama Museum of Natural History. (2008)
Because sunfish feed on similar prey items throughout their lives, competition occurs between young and adult fish. Centrarchids in general are top predators in many habitats, and a sunfish's main competitor may be other sunfish. Benthic organisms such as crayfish and other fish feed on eggs. In the closely related bluegill, cannibalism in areas of high nest density has been observed. This suggests that spotted sunfish could also be cannibalistic in similar situations. High densities of hydra were also linked to high mortality. Piscivores such as largemouth bass are predators of sunfish.
The spotted sunfish is a general habitat selector, but exhibits certain preferences. Juvenile and adults choose similar habitats, though younger fish sometimes show a preference for greater vegetation. It is a demersal fish that inhabits slow moving streams and rivers, swamps, and less brackish portions of estuaries. Spotted sunfish prefer heavily vegetated lake bottoms. Limestone, sand and gravel are preferred substrates. The Southeastern United States has acidic rain with a pH of 4.7-4.9. There is also a low carbonate hardness of Southeastern waters. This makes the area sensitive to acidification. Aquarists keeping sunfish have reported that they do best in neutral to high pH waters, in some extreme cases pH as high as 9.0 is observed. Acidification of their habitat could have negative impacts on the spotted sunfish.
Spotted sunfish typically reach a length of 9.8 cm (3.86 in), with a record of 20 cm (7.87 in). A maximum weight of about three ounces is common.
Like many fish, males of Lepomis punctatus may exhibit one of two different breeding behaviors. A bourgeois male builds nests, attracts females, and guards the eggs. Parasitic cuckolder males (sometimes called satellite males) attempt to steal fertilizations from the guardian male and leave him to guard the nest. Spotted sunfish cuckolders are visibly different from other males. They are smaller and less conspicuous, and often like a female or juvenile. Parasitic males may also display female mimicry, whereby the male mimics the behavior of a female to gain acceptance into a nest. This is thought to be common in centrarchid fishes relative to other fish. This behavior may help the guardian male by making his nest seem more attractive to females. Sunfish females prefer nests that are already populated by other females.
Bourgeois males as sires were shown to be far more common than parasitic males in a study by Dewoody, et al. Although nearly half of the nests showed evidence for parasitism, 98% of the embryos were sired by a single guardian male. When nest density is high a guardian male may fertilize nearby nests when the opportunity arises. Most nests in this study, 87%, contained eggs from at least three females, and most nests had five or more females.
The spotted sunfish has been shown to have potential as an indicator species. Spotted sunfish select habitats with high complexity and depth. They are frequently found in areas with woody debris that offer shelter from velocity and provides cover. Small decreases (0.30m) in river stage below base flow conditions resulted in 20–70% declines in a study by Dutterer and Allen. Though the spotted sunfish itself is not threatened, managing for this fish benefits the entire aquatic community. Similar centrarchids are preferred by anglers; the spotted sunfish must be closely watched to ensure that habitat is not modified for bluegill or redbreast sunfish at the expense of the spotted sunfish.
A threat to many centrarchids and potentially the spotted sunfish are invasive cichlids from the pet trade. The invasive Rio Grande cichlid ( Herichthys cyanoguttatus) has had negative effects on bluegill in New Orleans. The cichlid was aggressive towards the bluegill and took over some nesting sites. Several species of cichlid have become established in the Southeastern United States, particularly in the Everglades.[1] These species include the firemouth cichlid, convict cichlid, Mayan cichlid, and Salvin's cichlid. As with any invasive species, these should be monitored and removed if possible or practical.
There is potential that the range of invasive cichlids will increase as climate continues to warm . Conflicts between these invasive species and the spotted sunfish should be closely monitored. This would not only benefit the spotted sunfish, it could provide valuable information for all centrarchids.
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