Coral Reef Relationships | Smithsonian Ocean
Between predator-prey and competitive relationships, it may seem that organisms are Read about commensalistic and mutualistic relationships on the reef. than the last, as individual competitors become better and better adapted ("fit") to their environments. Read about different competitive relationships on the reef. Sponges are a group of common and diverse aquatic creatures, very abundant in coral reefs where they are an important part of the ecosystem.
Our multispecies year-long study subjected reef-building corals from the Gulf of Aqaba Red Sea to competitive interactions under present-day ocean pH pH 8. Results showed coral growth is significantly impeded by OA under intraspecific competition for five out of six study species. Reduced growth from OA, however, is negligible when growth is already suppressed in the presence of interspecific competition.
Using a spatial competition model, our analysis indicates shifts in the competitive hierarchy and a decrease in overall coral cover under lowered pH.
Collectively, our case study demonstrates how modified competitive performance under increasing OA will in all likelihood change the composition, structure and functionality of reef coral communities. Rising atmospheric carbon dioxide CO2 has recently exceeded ppm, the highest level in recorded history 1.
The resulting elevated sea surface temperature SST is accompanied by increased partial pressure of CO2 pCO2 in the ocean, which changes the relative amounts of inorganic carbon i. This process is known as ocean acidification OAand it is expected to have detrimental consequences on many marine ecosystems, including seagrass beds, kelp forests, tidal wetlands and mangroves 34.Symbiosis & Anemonefish - Reef Life of the Andaman - Part 18
It is important to note, however, that compared to open-ocean environments, pH changes in coastal waters derive from a complex interaction between anthropogenic CO2 emissions and dynamic regional to local drivers e. Coral reefs are particularly at risk from OA because the skeletal growth calcification of corals fundamentally depends upon the availability of carbonate ions in seawater 6.
Corals play a critical role in reef construction, and provide essential structural complexity for thousands of fish and invertebrate species e. An increasing body of evidence has revealed negative effects of OA on coral growth, reproduction and survivorship e.
However, uncertainty over the consequences of OA at the community and ecosystem levels remains because, to date, the majority of studies of the effects of OA have excluded the potentially important effects of biological interactions that form the foundation of coral reef community dynamics, such as competition OA can mediate competition among species because it influences both the supply of resources and the demand for them.
Male Spanish dancers Hexabranchus sanguineus essentially enter dance competitions to win their mates.
Spatial competition dynamics between reef corals under ocean acidification
The judge is the desired female, who decides which writhing, scarlet red male wins the right to father her offspring. This process is an example of "sexual selection," in which a male "wows" a female into mating with him. Often, as in the case of Spanish dancers, the male risks his life to put on a winning show, since his mating behavior makes him more conspicuous to predators.
Fortunately, Spanish dancers possess a potent toxin, which deters predators. Sea sponges and other sessile anchored organisms compete fiercely with each other for space using physical and chemical warfare. Over millions of years of turf wars, sponges that evolved anti-sponge toxins, like the Microcionidae, were often victorious over non-toxic varieties.
Thus, most sponges living today produce potent toxins, which provide a secondary benefit of discouraging all but the most highly adapted predators, such as the sea slugs. Competition for a common resource can exert pressure on a species to alter not only their physical form, but also their behavior. For instance, neither parrotfish Scarus spp.
Sponge competition may damage corals
Instead, they avoid predation by different adaptive behaviors. Parrotfish graze among schools of venomous, spined rabbitfish, which are seldom attacked by predators. Long-nosed butterflyfish Forcipiger flavissimuslike their parrotfish rivals, are not physically well protected against predators. Instead, both species have evolved behaviors that help them avoid being eaten while they graze for benthic algae.
Butterflyfish typically swim in pairs near a particular clump of coral. If threatened, they expertly wedge themselves between coral branches and erect fin spines so they are almost impossible to dislodge.
Competition For Resources - Coral Reef
Saddled butterflyfish Chaetodon ephippium mainly subsist on a diet of benthic algae; but they have also developed a taste for meat, and will rip tentacles from sea anemones if given the chance. Having evolved resistance to the anemones' toxins, the butterflyfish must still get past the smaller, but fiercely territorial, clownfish to steal a meal.
Sciencing Video Vault Sea anemones are also common sessile residents of coral reef.
Sea anemones are known for their mutually beneficial symbiotic relationships with clown fish and anemone fish. The tentacles of the anemones provide protection for the fish and their eggs while the anemone fish protects the anemone from predators such as the butterfly fish.
They may also remove parasites from the anemone's tentacles. Crown-of-thorns sea stars are well-known predators of coral reefs and have been known to devastate entire coral reef colonies.
This is a parasitic relationship in that the sea stars find food in the polyps of the coral whereas the coral is stripped down to its skeleton and left to die.