Gelatinous zooplankton blooms mess with fishery equipment, clog pipes and pose a threat to humans. Recently, certain events have moved the jellyfish to different environments outside their normal habitats.
The gelata is a term that encompasses all gelatinous zooplankton. Hydrozoa is a smaller phylum of gelata that has certain jellyfish in it.In the northwest Atlantic, the clinging jellyfish is being challenged by invasive jellyfish that are entering their habitat. The clinging jellyfish population dropped substantially in the early 20th century.The different jellyfish in different parts of the world have different effects on humans, some leave lasting damage while others are completely safe to handle and don’t sting. Northwestern varieties don’t have stingers, while those found in Japan have powerful stingers, meaning there was a bloom of newer and more toxic jellyfish. Northwest Atlantic and pacific jellyfish are related, not related to Northeastern pacific version of jellyfish. They all however came from the same original species.
These jellyfish are found in marine habitats known as eelgrass meadows, where they attach themselves using their stingers to the grass itself. They feed on passing zooplankton and have no main predators as they are very poisonous.The same eelgrass meadows that the jellyfish inhabit also house another invasive species, green crabs. They could directly prey on the jellyfish or destroy their habitat itself. The experiment yielded a food web interaction between the crabs and the clinging jellyfish that wasn’t recognized before.
The noninvasive crabs consumed the toxic jellies but the invasive green crabs did not consume them. The jellies were toxic if consumed in higher quantities, so they established their place at the top of the web by forcing predators to avoid them, making them the most abundant in the environment. If clinging jellyfish use their toxicity to avoid predation then they become the dominant species in its food web. In 2017 the experiment was done differently than in 2016 as there were 4 more jellyfish densities introduced. This means that there were new groups in which a crab was exposed to 4 different and increased levels of jellyfish, 10, 15, 20, and 30, according to the methods section. In the original experiment, these 4 new densities were not included. The graphs indicate the density of clinging jellyfish consumed by the native crabs in a certain period of time.
In graph A shows how jellyfish were consumed in a tub with a density or population of 5 jellyfish by the crabs in a 24 hour period. The first was consumed in the first four minutes, but the rest took 24 hours to consume. Graph B shows the same experiment except with a higher density of clinging jellyfish. Almost half of the 10 were consumed in the first 15 minutes, but the other 6 took 24 hours to be consumed.This graph shows the death rate of the crabs organized into the size of the crabs. They range from 50-58 mm, 60-69 mm, and 70-82 mm. The percent mortality increased with the size of the crab. This could be in relation to the amount of jellyfish consumed by the crab, and how quickly the toxins killed them.
The graph indicates directly the increase in mortality of the crabs that consumed the jellyfish by size. The graph shows the correlation between the starting density of clinging jellyfish and the percent mortality of the crabs that consumed them. The graph directly shows a positive correlation as when the jellyfish density increases, so does the percent mortality.
This is because the jellyfish are toxic, so the more that are consumed, the more toxins the crab consumes, which can kill them. More than 30 jellyfish being consumed is directly correlated to death, as those who consumed that many jellies died.Pg.10 Paragraph:1. The authors suggest there is a relationship as the crabs that consume the jellyfish encounter them frequently enough in the wild that consumption would kill them. This consumption kills and controls the native crab population, which allows the jellyfish to have dominance over the ecosystem.
The invasive crab doesn’t consume the jellyfish, and as the jellyfish kill their competitor, their population increases. The invasive crab can, therefore, take over the ecosystem as they aren’t hindered by the other crab species. They no longer have to compete for resources, and their population will go up as the other decreases. The jellyfish and the crabs have a direct relationship and impact on each other. Pg.12 Paragraph:3. The authors suggest the relationship is new as the clinging jellyfish has a new strain that makes it highly toxic.
In the jellyfish that came before the newest strain, they didn’t have the same sting or level of toxicity. If it was going on for a long period of time then it “would result in the evolution of jellyfish avoidance or toxin tolerance mechanisms, or the disappearance of crabs from jellyfish habitats.”. These are the natural reactions the crabs would have if facing a threat in their environment, but because they haven’t happened yet, the authors assume the relationship is new. The new strain is the most likely cause for this new relationship, and the new strain of toxic jellyfish have a correlation to an increase in stings reported in the area. The area before was devoid of a stinging jellyfish as “debilitating stings have occurred only in the past few years in Farm Pond suggesting the arrival of a new, highly toxic form.
” This toxic species shows the relationship was recently formed as the arrival of the new jellyfish started the interaction.Pg.13 Paragraph:2.
The interaction between the jellyfish and the native crabs could increase the population of the invasive crab species in the eelgrass meadows environment. The results show that only the native crabs consume the new strain of jellyfish, which is increasing mortality among the population. The native and invasive crabs “are likely competing for common prey resources. Thus Gonionemus-induced mortality of Libinia could benefit Carcinus populations by increasing prey abundance.” If there are no native crabs to compete with, then the invasive species get all the resources and increases in population. This could be detrimental to the environment as the invasive species is known to uproot eelgrass and completely destroy this habitat. The jellyfish is enabling the destruction of the environment it invaded by increasing the size of the invasive crab population.
In the discussion, I found the recording of stings very interesting. The jellyfish that invaded the environment were related to the new strain just by identifying a chemical in the sting. This allows them to make the logical assumption that the new species migrated there and invaded the eelgrass meadows as both have the same stings. Anyone further studying ecology at Martha’s Vineyard has to be aware of this new relationship and organisms present in it. They need to understand that the jellyfish is a new variant that has a powerful sting and is very toxic. They must also understand the relationship between the jellyfish, native, and invasive crab species that now inhabit the eelgrass meadows.
It informs them of the future of the environment if not altered, that the invasive crab species and jellyfish will take over and completely change the habitat. In summation, the study informs those studying the area that they are working in a changing environment that won’t remain the same for very long.