Brook stickleback

Appearance

The brook stickleback has a tapered body with a slim caudal peduncle and a fan-shaped tail. It very much resembles the ninespine stickleback but only has five, or occasionally six, dorsal spines. It also lacks lateral bony plates. Most of the year the colouring is grayish or olive green with a varying amount of indistinct mottling, but during the spawning season, males are nearly black and females have darker and lighter patches. This species grows to a maximum length of 3 to 5 cm.

Naming

"Culaea inconstans", commonly known as the brook stickleback, is a small fish (

Distribution

"Culaea inconstans", commonly known as the brook stickleback, is a small fish (

Habitat

As with a large geographical distribution, this species also lives in a wide range of flowing water habitats. Waterways such as rivers, streams, floodwater streams and drainages, lakes, ponds, potholes, hot springs, sinkholes, and seasonal melt water or spring fed ponds are all viable brook stickleback territories. Though the species can thrive in these habitats, primary spawning, breeding, and rearing grounds are located in shallow near shore environments with high vegetation cover and low velocity water. The species has a wide elevation range with specimens identified from sea level to ~ 2,400m.

Food

The brook stickleback is an omnivore, with primary feeding tendencies toward aquatic insect larvae, adult terrestrial insects, crustaceans, fish eggs and larvae, snails, oligochaetes, nematodes, rotifers, and mites. However, brook stickleback feed on vascular plant material, as well as algae. Newly hatched stickleback larvae and planktonic crustaceans from both streams and ponds. Juveniles eat small organisms due to mouth size restrictions, and adults eat both large and small organisms.

Predators

Certain large invertebrates, birds, mammals, and fish all prey on the brook stickleback. With its small size, this species of stickleback has evolved piercing spines and protective plates to hinder predators. With this protection, as well as advanced anti-predator behavior, the brook stickleback is only a minor prey item. In a lab study, adult water bugs and dragonfly nymphs both successfully preyed on the stickleback, but only in a night setting. Fish have been observed to be the most successful predator of the brook stickleback. Examples of these fish predators include: yellow perch, rock bass, creek chub, burbot, central mudminnow, smallmouth bass, largemouth bass, northern pike, brook trout, rainbow trout and round goby. Brook stickleback eggs can be cannibalized, as well as consumed by rainbow trout. Competition among the ninespine stickleback exists. However, ninespine stickleback habitat exists in the pelagic zone, while the brook stickleback occupies the littoral zone. In the presence of fathead minnows, the brook stickleback has a more diverse diet since the fathead is a more generalist feeder.

Evolution

For this particular species, spawning occurs in mid-summer. Brook sticklebacks migrate annually up affluent streams and creeks of rivers and lakes during the spring to spawn in weedy areas. Spawning occurs as males secure a protected territory and construct a nest. These nests are constructed using algae, roots, and aquatic vegetation. There is one entrance with no exit. When the female enters, she deposits her eggs by shaking violently. Each shake allows more eggs to be deposited. Once all the eggs have been placed, the female must push her way through the wall of the nest to exit. During this process, studies have shown that the female makes acoustic noises, which is thought to advertise to sneaker males, as this can increase the proportion of eggs fertilized. After spawning, the male assumes protection of the eggs which hatch in 7–11 days. New hatched stickleback can wander from the nest, but the male gathers them into his mouth to deposit them back in the protective nest. Spawning usually ends around mid-July due to swift temperature changes in the water. The newly fertilized eggs are vulnerable to slight temperature changes. These fish grow rapidly during their first summer and typically reach sexual maturity by spring of the next year. Most adults die within the spawning season or shortly after causing them to be deemed an annual species.