Ecology is the study of interactions between organisms and between organisms and their environment (home).
As humans, we are all part of the ecosystem. As every other organisms, we interact with our environment, we both depend on ecosystems for our survival and have an impact on them. We can indeed change ecosystem in many different ways.
Understanding what are the effects of our activities on ecosystems is crucial in order to avoid our actions to have unintended consequences (such as the decrease of fish stocks due to overfishing). Our activities can have direct negative consequences for us as humans (flood, drought…) but also provoque species extinction for example.
If we want to conserve and protect ecosystems, we need to understand how species and their environment all fit together. In other words: what do species need in their habitat? how different species influence each other? what are the minimum population sizes to ensure their survival?… To be able to manage natural areas, ecology is important!
Experimental studies allow to simplify processus occurring in ecosystems
Experimental studies allow to simplify the system by controlling all variables except for the one we are interested in. But designing ecology experiments around something as complex as ecology might sound overwhelming. So in this serie of articles, I am going to explain you the different steps to conduct an experiment in marine ecology with a concrete example (i.e. one of my own experiment).
Steps to conduct an experiment:
#1: Defining your questions and hypothesis to plan your experiment
#1 Defining your questions and hypothesis to plan your experiment
Watch our case study:
1.1. Begin by doing your research
Before conducting an experiment, research is necessary to gather information on the current knowledge. You can do so by reading literature and asking experts. You will use all the gathered information to formulate hypotheses and to design the experiment.
In our case study
What is known and what is missing?
Coastal ecosystems have highly valuable goods and services for human society and provide important ecological functions (such as primary and secondary productions and nutrient cycling).
Invertebrates living in those areas, such as worms, play an important role by linking organic material with predators, providing food to fish for instance. However, in the last decades, these areas have been experiencing increasing threats, mainly due to human activities. They are particularly vulnerable to species introductions. The Baltic Sea is a very special environment with its brackish water and low number of species. This contributes to non-native species establishment.
The number of worm species is very small in the northern Baltic. Consequently, the introductions of two worms, Boccardiella ligerica and Marenzelleria spp., represent a substantial increase in polychaete diversity. Usually, species invasions are considered as a major threat to ecosystems. However, given Boccardiella abundance in some brackish habitats, this species may play an important role in estuarine food webs, as a consumer of phytoplankton and detritus, and as food for small fishes and predatory invertebrates. Regarding Marenzelleria worms, they have a different way to move in the sediment than the local species. They could then be potentially positive for the ecosystem. Predators could also benefit from their presence.
1.2. Identify a problem
The problem is the question you are trying to answer. Without a problem, there is no reason for conducting an experiment.
In our case study
Aims, questions, issues
Based on the literature, some questions emerge:
How these worms impact other invertebrates in sediment?
Do those two different species of invasive worms have a different impact?
What are the consequences of these effects on predators?
1.3. Formulate hypothesis
The hypothesis is a statement, based on your research, that is intended to provide a solution to the problem. The hypothesis is what you are trying to prove or disprove.
In our case study
Again, based on the literature review, we are able to formulate some hypotheses:
How these worms impact other invertebrates in the sediment? We expect non-native worms to have no effect on big invertebrate species but to impact smaller ones.
Do those two different species of invasive worms have a different impact? Due to their different behaviour in the sediment and size difference (Marenzelleria spp. are bigger than Boccardiella ligerica), we expect the two species to have a different impact.
What are the consequences of these effects on predators? As the predator selected is an opportunist, we expect a change in their diet.
[q multiple_choice=”true”] How to plan an experiment?
What is the first step to set up an experiment?
[c] To come up with questions and hypothesis
[f] This is indeed one of the first step but another important task comes before, try again!
[c] To collect animals you want to put inside of the aquariums
[f] This is a step that comes after planning your experiment.
[c*] To check the literature
[f] Well done! Before starting an experiment or any scientific studies you need to know the curent state of knowledge.
[c] To ask other people for advices
[f] This is actually a good idea to ask questions to your colleges, advices are always wellcome and this can also lead to really nice opportunities to collaborate. But do not only rely on others to plan your experiment.
[q] Why the Baltic Sea is such a special environment? What makes this environment so ideal to plan experiments?
[c*] Show me the answer
[f] Due to its brackish water, young ecological age, very few species can live there. There are a low number of species and few dominant invertebrate species. Ecological processes are simplified.
[q] What is brackish water?
[c*] Show me the answer
[f] Brackish water is water having more salinity than freshwater, but not as much as seawater. It may result from mixing seawater with fresh water together, such as in estuaries.Some seas and lakes are brackish. The BalticSea is a brackishsea adjoining the North Sea.
[q multiple_choice=”true”] How to come up with questions and hypothesis?
[c*] Do your research by reading litterature
[f] Well done! Reading research already done in your field will help you identify the state of the curent knowledge: what is already known and what is missing.
[c] You need to be really smart!
[f] No worries! You don’t need to be a genius to do science and come up with questions: just be curious 🙂
(enter text or “Add Media”; double-click to format)[restart]