Marine turtle research and conservation in the Mediterranean Sea: the thirty-year commitment of the Stazione Zoologica Anton Dohrn of Naples.

By Fulvio Mafucci

The Stazione Zoologica of Naples (SZN) is one of the oldest marine biology institutes in Europe. Its foundations were laid in March 1972 thanks to the incredible willpower, diplomatic skills and a good dose of luck of a young German naturalist, Anton Dohrn. He was able to persuade the local authorities to give him, free of charge, a piece of land along the beautiful coast of the Royal Park in Mergellina to create, at his own expanse, this marine biological station (Figure 1).

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Figure 1. Stazione Zoologica of Naples. © Stazione Zoologica of Naples.

Today the SZN is a National Research Institute whose mission is research on fundamental biological processes with specific reference to marine organisms and their diversity. One of the most iconic species that has a long tradition of studies at the SZN is the loggerhead turtle, Caretta caretta (Figure 2). Drawing of these magnificent animals were present in commercials of 1902 advertising the institute’s public Aquarium and the first experiments on loggerhead turtles were carried out in 1938. Forty-five years later, in 1983, the sea turtle research and conservation project was launched to respond to the increasing threats that sea turtles were facing due to the ongoing degradation of marine ecosystems. The project aims to provide a sound scientific basis for the development of effective management strategies of these charismatic animals. The research activities focus on the Mediterranean population of the loggerhead turtle, Caretta caretta, a priority species to the European Union under the Habitats Directive 92/43/EEC. The project explores different aspects of biology and ecology of the species, and is developed in four complementary themes:

  • Population structure and connectivity
  • Dispersion, movements and behavior
  • Health and physiology
  • Human impacts including climate change

Respect to this last point, one of most recent studies conducted at the SZN explores the possible influence of climate warming on the loggerhead turtle nesting range expansion in the Western Mediterranean Sea. Climate warming is a major challenge to Earth’ biota that forces species to adapt in situ or move to a different location in order to track shifts in environmental temperatures. Many different marine taxa have already shifted their distributions to endure changes in ambient temperature. In particular, marine ectotherms, such as the loggerhead turtle, are expected to colonise northern habitats as they become suitable for colonists due to the ongoing climate warming. However, the pace of redistribution depends on species-specific traits that may promote or hamper expansion to northern habitats.

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Figure 2. Caretta caretta. © Stazione Zoologica of Naples.

The SZN study shows that recently, the loggerhead turtle has begun to nest steadily beyond the northern edge of the species’ range in the Western Mediterranean basin. This range expansion is associated with a significant warming of spring and summer sea surface temperature (SST) that offers a wider thermal window suitable for nesting. Moreover, the increase in summer temperature has resulted also in higher hatching success rates and female production, which are two conditions essential for the future colonization of the area. However, the study shows also that post-hatchlings departing from this location experience low winter SST that may affect their survival. The persistence of cold winters is due to the different dynamics of winter and spring SST responses to climate change in the Mediterranean Sea. Based on the current information, it is still not possible to forecast precisely when the thermal conditions at this post-hatchling developmental habitat will become sustainable. However, the observed seasonal heterogeneity of ocean warming may lead to a conundrum where the number of exploratory females and hatching success will increase with climate warming but the stabilization of this Western Mediterranean nesting site will still be hampered by high mortality rates of post-hatchlings due to the persistence of low winter temperatures. Clearly, this seasonal response to climate change might have implications for other marine organisms with a complex life cycle and it deserves further investigations. Proactive conservation measures are critical to protect and restore this potential hot spot for poleward expansion of loggerhead turtles nesting range in the Mediterranean Sea.

Besides research activities, one of the most significant part of the sea turtle research and conservation project at the SZN is the rescuing of turtles found in difficulties with the aim to rehabilitate and release them back into the sea (Figure 3). On January 2017, the SZN inaugurated the new Marine Turtle Research Centre – Observatory of the Gulf of Naples (MTRC). This is a centre of excellence for sea turtle research and rehabilitation and for scientific dissemination. It consists of six hundred square metres of covered space and seven thousand square metres of external space, with advanced laboratories for environmental analysis. It is equipped with a nursery, a hospital to treat injured animals with quarantine, surgery, emergency room and x-ray, a rehabilitation area, research laboratories and a didactic exhibition. It has 25 individual tanks for sea turtle rearing, raging in volume from 1.5m3 to 3 m3, arranged in 10 recirculating aquaculture systems (RAS) with mechanical and biological filtration, temperature control, UV and Ozone treatments. Each system is provided with fresh water and filtered seawater. The didactic exhibition hosts 6 aquaria and several multimedia interactive devises dedicated to the descriptors of the Marine Strategy Framework Directive and the research and conservation activities conducted at the SZN. Due to the charisma of the loggerhead turtles, the state of art facilities and the modern educational interactive tools, the MTRC has the potential to become one of the most important no-profit cultural site in the South of Italy to promote marine ecosystem conservation and the leading centre in the Mediterranean Sea for marine turtle research, education and rehabilitation.

Figure 3. Caretta caretta . © Marco Gargiulo.

Fulvio Maffucci is a member of the Marine Turtle Group of the SZN since 2002. His main research interest is the connectivity and stock composition of loggerhead turtles foraging in the Mediterranean Sea but he also provides technical assistance for the design and maintenance of life support systems (LSS) and experimental tanks for the Marine Turtle Research Center and the Public Aquarium. He came to the ECIMAT for a two months training in the management of facilities providing services and technical support to marine biological researchers and to broad his knowledge on procedures for the rearing of marine model organisms that can be potentially of interest for the SZN.

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