Lívia Lang

Abstract

Gorgonians are among the most important habitat-forming species of benthic communities in the Mediterranean Sea. Through their three-dimensionality they create underwater forests, so called coral gardens. These coral gardens enlarge structural complexity and biomass of a habitat and moreover enhance surrounding species diversity. Gorgonians are sessile colonial organisms that can be found in reef habitats all around the world. Due to being sessile organism with slow growth rates and general longevity, gorgonian gardens are representing a highly vulnerable marine ecosystem. Healthy gorgonian gardens are associated with an array of ecosystem goods and services, thus adding value to the ecosystems in which they are found. This study represents a first-ever quantitative health assessment of gorgonian species in Gibraltar. The main aim of this project was to assess the health status of gorgonian species, focusing on four representative species that inhabit the Mediterranean Sea: the white gorgonian – Eunicella singularis, the pink gorgonian – Eunicella verrucosa, the red gorgonian – Paramuricea clavata and the sea fan Leptogorgia lusitanica. Furthermore, it was aimed to present and evaluate a standardised monitoring protocol. Following a comprehensive critical and synthesis review of relevant literature, a non-destructive photo quadrat sampling method was conducted by scuba diving. The assessment was carried out on an artificial reef in Gibraltar. All four species were highly represented at the study area, with E. singularis as the most predominant one. In sum 158 individual colonies have been investigated. It was found that over 63% of the total amount of colonies were affected and 9% were dead, hence less than 28% were perceived healthy. E. verrucosa exhibited the highest percentage of injury with a value of 81%. All species were existent on similar depth levels. There were differences on species level, as well as minor differences according the distribution of species. Overall, gorgonians exhibited a high epibiotic cover. Predominantly two non-indigenous invasive algae species were overlaying on them: Rugulopteryx okamurae and Womersleyella setacea. Moreover, epibionts also consisted of hydrozoan, poriferan, bryozoan and even other encrusting anthozoan. Multivariate statistical results indicated that epibiosis, abundance of healthy and of affected/injured species are the main factors leading to differences across the research site. In general, findings of this study indicate an overall poor health condition of the species investigated at the artificial reef in Gibraltar. By assessing the current health status of gorgonian corals, this research hopes to improve the current knowledge about coralligeneous communities and the main abiotic and biotic factors causing the poor health status.

Read more about Livia’s research here.

Keywords: gorgonian, health status, epibiosis, artificial reef, non-indigenous invasive species, monitoring

Primary Supervisor:               Dr Awantha Dissanayake

Secondary Supervisor:          Dr Jaime Davis, University of Plymouth

Advisor:                                   Dr Darren Fa

 In conjunction with:

Mr Clive Crisp, DESCCH – Department of Environment, Sustainability, Climate Change and Heritage

Maïté Kesteleyn

Abstract

Gibraltar is one of the 22 countries located around the Mediterranean Sea, which is commonly known for being a hotspot of biological diversity. Only a small amount of studies exist assessing the marine environment and its biodiversity by using a fixed underwater camera as a monitoring tool. Within the six weeks of observing the underwater camera of Gibraltar, it was operational for approximately 65 percent. Every day the underwater camera was active, three recordings took place, in the morning, midday and evening. Ten families, 20 genus and 32 species were positively identified form a total of 15493 individuals. Nevertheless, 301 individuals remained unidentified (1.1 %). Results showed the morning recordings obtained the highest biodiversity level (0.76), achieved through Simpson’s index compared to the midday (0.68) and evening (0.75) recordings. Throughout all the recordings, the Sparidae (breams) and Labridae (wrasses) families appeared most. Three identified species are retrieved on the red list, labelled vulnerable.

The contribution of citizens was asked for and received. The number of footage sent in, appeared to be four times as high. Simultaneously, the interaction and curiosity received from the participants increased. WhatsApp is proved to be the preferred social network platform to sent photos through (50 percent of the time), compared to Facebook and Email, each chosen 25 percent of the time as method to sent photos. To increase awareness involving the marine biodiversity within the British Gibraltar Territorial Waters, a biweekly post took place on two different social media platforms, Twitter and Facebook. The interaction (shares, likes, reactions) on these posts was decreasing on Twitter as opposed to increasing on Facebook.

These results are significant to adjust practices in place. The underwater camera, has its challenges. Therefore, the limitations together with suggestions for improvement and potential solutions are discussed. Compared to other methods, the fixed underwater camera has proven to be a promising marine monitoring tool.

Read more about Maïté’s research here.

Keywords: Underwater camera; Biodiversity; Marine monitoring tool; Management; Stakeholder; Citizen Science; Gibraltar; Fish; ProjectSEACOMM

Primary Supervisor:               Dr Awantha Dissanayake

Secondary Supervisor:          Dr Darren Fa

In conjunction with:

Stephen Warr: Department of Environment, Sustainability, Climate Change and Heritage