Damselfish 'garden' algae | EurekAlert! Science News
A species of damselfish, Stegastes nigricans, selectively weed the algal gardens on which they feed in order to encourage the growth of their preferred algal species of Polysiphonia and suppress the growth of less palatable algae. In a new study, researchers investigate the. Many reef fish species decline in abundance as coral cover is lost, yet the space between branches as dead corals become overgrown by algae. changes in predator-avoidance behaviour of a common damselfish, . For example, the common reef fish Chrysiptera arnazae (previously C. parasema). Neon damselfish from East Timor Habitat Many species live in tropical. Chrysiptera parasema, also known as yellowtail damselfish, yellowtail blue damsel, goldtail  Causes Coral and microscopic algae have a symbiotic relationship.
This is the first documented case of algae inhabiting the cells of any vertebrate. Algae had previously been known to inhabit the cells of many single-celled organisms and certain marine invertebrates, including sponges, corals, and sea anemones.
The predominant understanding with vertebrates, however, was that their more advanced immune systems destroy any foreign body entering their cells. The algae become noticeable inside the salamander embryos just as cells begin to organize into specific tissues, particularly the nervous system. Before and after this stage, algae are much less abundant inside the cells. This explains in part why the phenomenon took so long to discover — scientists were not examining the salamander cells at just the right moment in their development.
Furthermore, the algae are very difficult to see using traditional light microscopes; only the use of fluorescent and electron microscopes enabled Kerney to detect algae in the salamander cells.
This remarkable discovery has opened much scientific inquiry into related issues — including the fundamental question of how the algae get inside the cells. Kerney and colleagues have discovered O. The exact mechanism is unclear, but seems to be related to elevated levels in the host cell of a lipoprotein that triggers endocytosis — the formation of a concavity on the cell membrane that takes in the foreign body and eventually surrounds it.
So if endocytosis is indeed happening, then there must be some yet-unknown way by which the algae escape the sac that swallows them up. Then there is the question of what happens inside the salamander cells.
Kerney and colleagues have observed that salamander mitochondria organelles that carry out cell respiration congregate around the algae, affirming that the embryonic cells probably respire using oxygen and carbohydrates produced by the algae.
Furthermore, the most recent research, published in May by John Burns and colleagues, illuminates why the embryos tolerate the algae — one specific immune response pathway involving a protein family called NF-kappa-b seems to be suppressed. As current speeds increase, it forages closer to the bottom of the column.
Feeding rates tend to be higher when currents are faster. Smaller fishes forage closer to their substrates than do larger ones, possibly in response to predation pressures. Females leave their territories temporarily during spawning in order to deposit their eggs in male territories.
This increased mobility subjects them to greater risks of predationand females typically exhibit higher turnover rates than males do. Male damselfish defend their clutches until the larvae hatch. They do so by continuously swimming in a circular pattern around their nests. Males compete against each other for reproductive territorial space.
The Symbiotic Relationship of Algae and Spotted Salamanders | Finger Lakes Land Trust
Smaller and less aggressive individuals are often relegated to secondary or suboptimal habitats and therefore exhibit lesser reproductive success. Some are excluded from establishing territories altogether and usually exist as a floating population.
These fish do not take part in breeding and are at the greatest risk of predation. However, they may occupy territories that have been vacated whenever the opportunity arises. These territories provide them with hiding spots, dietary needs, and spawning sites. Individuals in suboptimal territories frequently attempt to relocate, and so those in optimal habitats must constantly monitor territorial occupancy.
Territorial aggression is often proportional to territory quality. Movements outside of territorial borders, called forays, are common and may span distances of sixteen meters or more. Three types of forays exist. The shortest-distance ones are involved in foraging.
Longer forays usually involve courtship activity and mating.
Non-feeding and non-reproductive forays are associated with territorial reoccupation. Courtship In the species S. Even though large male size can be advantageous in defending nests and eggs against conspecifics among many animals, nest intrusions are not observed in this damselfish species.
Females also do not choose their mates based upon the brood sizes of the males. In spite of the increased male parental care, brood size does not affect egg survival, as eggs are typically taken during the night when the males are not defending their nests. Rather, female choice of mates is dependent on male courtship rate. Males signal their parental quality by the vigor of their courtship displays, and females mate preferentially with vigorously courting males.
The signal jump involves large amounts of rapid swimming, and females choose mates based on the vigor with which males do so. Females determine the male courtship rates using sounds that are produced during signal jumps.
As the male damselfish swims down the water column, it creates a pulsed sound. Male courtship varies in the number and rates of those pulses.
Female size is significantly correlated with ovary weight, and males intensify their courtship rituals for the more fecund females. Research has shown that males that mate with larger females do indeed receive and hatch greater numbers of eggs.
Among this species, evolutionary selection favors those males that begin mating as soon as possible during spawning seasons even if the most favorable egg clutches are spawned at later times.