Marine Mammal Research and Conservation - Internship in the Aegean Islands, Greece
The development of this Professional Practices has been conducted in a remote way in collaboration with the Archipelagos Institute of Marine Conservation, that is a partnership of the International Master of Science in Marine Biological Resources (IMBRSea). The project has been realized during 8 weeks and 3 people have been involved: the supervisor Patrice Hostetter, another IMBRSea student called Margarida Rolim and me (María Cajal Mifsut).
Even if Margarida and me have both been working in Photo-Identification and behavior analysis, at the end each of us had to write a research paper and mine was more focused in the distribution of short-beaked common dolphins in the Aegean Sea and their behavior, whereas her was more concerned in Photo ID.
The study area is placed around the Aegean Islands (Greece), mainly around the island of Samos.
Cetaceans of the Aegean Sea
Why Photo-identification?
Life history of the animal
Behavior patterns, emigration and remigration of individuals
Site fidelity (long or short term)
Reproductive biology
Abundance estimates/area distribution
Group structure and social organization
Photo-Identification
Photo identification studies are based on the identification of every individual of a population through a photograph thanks to their natural markings, it provides a non-invasive method of identifying and following individuals over time.
Identifiable markings are a product of intra-specific interactions (dolphins engaging with other species of animals), inter-specific interactions (among themselves), environmental and anthropogenic factors (collision with boats, fishing lines...).
As in the Mediterranean Sea there are numerous different species of marine mammals, the first thing to do when identifying a mammal from a photo is to identify the genus and species.
The pictures are taken perpendicular to the dolphin´s body axis concentrated on the dorsal fin, at 90º angle. The dorsal fin is the most diagnostic feature, unique for each dolphin from incidental events unless otherwise unmarked. The photographers should take pictures of as many individuals of the group as possible, covering both sides of the boat trying to get both sides of the dolphin´s dorsal fin.
For the Photo ID it is necessary to look for the Picture Quality and the Distinctiveness:
Distinctiveness
Highly distinctive (D1): Individuals have highly distinctive major nicks/notches.
Distinctive (D2): Individuals have less distinctive minor nicks/notches. Alternatively, individuals have a distinguishable pigmentation pattern (mainly in common dolphins).
Non-distinctive (D3): Individuals have no distinctive nicks/notches nor a distinguishable pigmentation pattern
Picture Quality
Excellent (PQ1): No apparent pixelation of the picture, small details of the dorsal fin pattern are easily identifiable and the smallest notches and dents are visible.
Good (PQ2): Pictures only show a small level of pixelation, minor nicks/notches can be seen.
Insufficient (PQ3): Pictures are considerable pixelated.
Poor (PQ4): Pictures are strongly pixelated.
Examples
Left picture: D1,PQ2
Middle picture: D2, PQ1
Right picture: D3, PQ2
We should also see the orientation of the dorsal fin:
Left picture: Right side
Middle picture: Left side
Right picture: Left side
Matching
When the distinctiveness and the picture quality have been assessed, the Internal Matching should be done, because it is easiest to do an internal matching within the sighting before matching with the hole catalogue.
Then the individuals can be matched with the individuals of the catalogue, the easiest and most reliable features to identify individuals are nicks and notches on the trailing edge of the dorsal fin. For doing the matching it is recommended to open the target picture on one side of the screen of the computer and the catalogue on the other side, so that it is possible to scroll up and down through the catalogue and look for possible matches, like in the image below, in which we can observe a match between our target picture and Clarence from the catalogue.
In the external matching it is possible that some individuals appear several times and that they are not in the catalogue, they should be included. Margarida and me found 4 new individuals that had to be included and we had the privilege to name the individuals (2 each), I named mine Furby and Faro.
We will assess behavioral patterns of the short-beaked common dolphin (Delphinus delphis), according to habitat use around the Aegean Sea. Understanding the different behaviors seen, particularly when the individuals of a population can be recognizable for example by photo ID techniques (O'Brien et al., 2009) is very important to provide baseline scientific data for many avenues of study.
Behavior analysis of short-beaked common dolphins with BORIS
The behavior of dolphins can be affected by a wide range of variables. Behavior studies can give valuable insights into both individual and population health and allows us to make further analyses of factors such as behavioral bouts and activity budgets.
It is important to standardize categories and terms used in behavioral research in ethograms that are an essential tool in the study of animal behavior and are very important for understanding the behavioral ecology of a specie and it make easier the recording of data (Baker et al., 2017).
In the study of animal behavior, it is of great importance to distinguish between states (long-lasting behaviors), events (shorter behaviors that can occur at the same time as a state) and categories (combinations of events and states to make a more specific behavioral record) (Friard and Gamba, 2016).
BORIS, or the Behavior Observation Research Interactive Software, is a tool that we can use to record the different behaviors of animals.
Ethogram
An ethogram is a inventory or catalogue of behaviors or actions exhibited by an animal used in ethology. It is composed by States, Events and Categories.
The main States or long lasting behaviors were Swimming (the dolphin is swimming below 1m underwater, randomly at any speed (slow/medium/fast) and Diving (dolphin dives in no steadily movement, it often occurs when feeding).
The ethogram had 17 different Events, see some examples:
Belly up: the dolphin is in ventral position with its belly exposed to the surface of the water.
Bow: dolphin jumps forward in a dorsal position. The length of the jump is less than the body length of the dolphin and there is no splash.
Bow riding: dolphin swims or makes forwards movement along the boat, between the surface of the water and 1m depth.
Breach: Anterior limbs of the dolphin are out of the water in lateral or inverted position, there is a noisy splash.
Mating: dolphin shows quick reproduction ritual by belly to belly contact.
Tail out: dolphin arches its back and exposes its caudal fin as it dives (surfacing type)
And 6 Categories (combinations of events and states to make a more specific behavioral record), like:
Feeding: dolphin is feeding close to the surface, often moving in circles and diving in different directions. Usually there are birds concentrated in the area.
Socialising: dolphins are in almost constant physical contact with each other.
Travelling: dolphin is swimming in a consistent direction with regular surfacing intervals.
BORIS procedure
The first step is to record the videos on the boat as a non-stop video during all the sighting at the same time as the Behavior Data Sheet is being filled.
Then at the office, the second step is to create an Ethogram with all the known behaviors classified in states, events and categories. We save it as a template so that we do not have to create it every time with every video.
When we upload a new video as "New observation" we have the possibility to add some independent variables like Sea state, Number of individuals, Specie, Location, etc.
The video should be played and every time the dolphins do something, by clicking in the behavior of the ethogram (on the left of the screen) it gets registered (right side of the screen), State events requires 2 clicks, once to signify the start and once when it is over, Point events only require a single click. At the end of the video a table of behaviors should be produced, that by collect them in an excel file it is possible to do different data analysis, like map the behaviors with GIS.
Different behaviors mapped in the Aegean Sea
In case someone is interested in know how the BORIS software works, the following instructions have been designed around a video tutorial available on YouTube:
