I am Jan and I am studying marine sciences at the Scottish association for marine sciences in Oban. I have joined the marine ecology team here on Lipsi between July and October 2020 and I recently set up a project on macro-invertebrates and their abundance/activity on different substrates and at different times of the day.

A typical day for me includes a morning survey, in which I record all mobile and sessile macro-invertebrates on two 50m transect lines (one on rocky substrate and a second one on sandy bottom) on one off my 5 surveying-sites around Lipsi island. I record these animals using an underwater camera and then analyse the footage, by counting the abundance of each species in the afternoon.

In the evening, right after sunset, I usually do my second survey, following the same transect lines I did in the morning but in the dark, using diving torches. Only mobile macro-invertebrates are being recording for this part of the survey, as sessile species are easier to spot during the day and their abundance won’t differ at night.

So far, I have found a general increase of macro-invertebrate abundance at night compared to day time, especially amongst certain species like Hermodice caranculata (Fireworm), Astropecten spinulosus (Slender sea star), Holothuria forskali (Type of sea cucumber) and others. In addition to this, a considerable increase of all sessile macro-invertebrates can be observed on rocky habitat compared to a sandy habitat, on which very few invertebrates can be found at the depth we survey at.

In addition to comparing abundance of macro-invertebrates at different times of the day and on different substrates, I use my surveys to monitor invasive species around Lipsi, by recording any invasive invertebrates present along the transect lines. This mainly includes the invasive long spined sea urchin diadema setosum and the invasive sea cucumber synaptula reciprocans.

The data I am collecting can be used to answer my research questions, but over the long term, replicating the transect lines and collecting the same amount of data at the same sites can be an indicator of the evolution of the health of the ecosystems around Lipsi island. Indeed invertebrates being either sessile or spending most of their lives in comparably small areas and certain species being quite vulnerable to changes in nutrient concentration, temperature of the water, pollution in the water. Therefore, a change in general abundance or a change in the type of species predominantly present around Lipsi will indicate a change in the general health of the ecosystem.

Janika Sander
Student of Marine Sciences at the Scottish Association for Marine Sciences in Oban
On-site intern at Archipelagos’ Marine Conservation Team