What an amazing summer we have had researching European seahorses at Seahorse City!
Our total count in the seahorse photobase is now 54 individuals identified, with 26 of those being new discoveries this season. 5 Hippocampus hippocampus and 11 Hippocampus guttulatus returned to our study area to breed, one pair for the third year running. Of the new seahorses found this year, 16 were H. guttulatus females.
Volunteer research divers at Seahorse City have set several records this summer in terms of the numbers of seahorses found per survey and also the unusual nature of some individuals or behaviour observed:
- First black seahorse
- First one-eyed seahorse
- First inter-species mating filmed*
- First data on breeding cycles
- First data on synchronised breeding between two pairs living 45 meters apart
- Smallest individual
- Smallest pregnant male
*That was a big surprise as there is little known about this phenomenon and also because the pair were known from 2014 when they were definately not a couple.
Our one-eyed seahorse, Beauty, is doing well and is seen regularly. However, she is not alone. Another one-eyed individual was found, and named Jack. He has been breeding with Blondie, who was first seen in 2014, and we were able to monitor two of his pregnancies and also film them mating. Quite a few eggs were lost, as he is smaller than her, as you can see in this photo by volunteer Jasmine Corbett, but during the peak breeding season they were mating every 16 days!
One-eyed Jack has a normal colouration and I recently found another black individual, who I named Zebra due to his whitish stripes, that has both eyes. Therefore, Beauty is probably naturally black, rather than changing due to stress, which is good.
We have continued to share our data with The Seahorse Trust (as a member of the Seahorse Alliance) and with Project Seahorse. Both organisations have been impressed with the quantity and quality of our observations as citizen scientists. In fact, the Seahorse Project is the only seahorse research group to contribute a whole year of data to the Project Seahorse world-wide database using their Trends Toolkit.
Although many volunteers have been marine biology students enjoying affordable work experience, regular divers with good buoyancy skills and a keen eye have been just as successful in spotting seahorses.
For example, Chris, from Belgium, spotted the tiniest male - who turned out to be the smallest found to be pregnant. Another great example is Louise, who found a seahorse in a totally different location whilst surveying bryozoans for our Silmar Project research.
Volunteers who find a new seahorse are rewarded by choosing its name. We now have seahorses named after most of our volunteers, their relatives, and even a beloved pet!
Many of the seahorses that research volunteers were monitoring last summer have returned to to breed again this summer. Danny and Queenie are still a couple, and Danny has had at least one pregnancy so far. They have adopted a different territory within the Seahorse City area this year. Eagle-eyed volunteer research divers have also spotted several new individuals, and had the honor of choosing their names.
A strange finding was a black female Hippocampus hippocampus that we've named Beauty. Normally they are well camouflaged to blend in with the algae or dead Posidonia oceanica roots. The black female was vulnerable as she really stood out against the sand and algae and could be spotted by a tourist or predator. She was also missing her right eye, making her doubly vulnerable to being eaten by the many octopus living there! We expected to find her easily when we returned for a second survey dive, but she had disappeared.
According to The Seahorse Trust, with which we form part of The Seahorse Alliance, the dark colouration was dues to stress. No wonder after losing an eye, although the injury did not look very recent. Seahorses are very susceptible to stress, and carry dormant viruses that can mulitply and cause the death of the animal if stress is prolonged. This is why we do not use flash when photographing them. Let's hope that she has hidden herself away successfully and we are able to find her again, and monitor her throughout the summer.
Our conservation research season has started and a seahorse survey dive in a secret location on the Costa Brava, Spain, this month revealed the first returner to the Seahorse City research area. She is a Hippocampus guttulatus named "White Eyes". Located about 25 meters from where she was living last summer, she was alone and the male thought to be her mate, "Mike", was not seen on this ocassion.
Algae is beginning to develop to provide the cover that seahorses require when feeding outside the relative safety of the Posidonia oceanica seagrass meadow. However, the lovely weather has brought many tourist boats that are anchoring in and around this area, causing considerable disturbance. In fact, apart from a few large features, it was very difficult to recognise the specific spots where last summer's 28 individual seahorses were living and being monitored.
The seahorses' preferred food source – mysis shrimps - is now in evidence, but not as plentiful yet as during the height of summer. The unusually high April/May temperatures are warming the Mediterranen sea quicker than last year, which will reinforce the increasing daylight hours effect upon the seahorses' egg production and the length of gestation. This should result in a bumper year for seahorse reproduction at Seahorse City!
An article on the Seahorse Project has been published here with a video of "Mr Itchy" showing his comical scratching behaviour last summer. Fortunately he survived the parasite attack and stopped scratching.
Volunteer research divers who join for at least three weeks are able to take part in the Seahorse Project research.