Núria Viladrich

Variation in lipid and free fatty acid content during spawning in two temperate octocorals with different reproductive strategies: surface versus internal brooder

AbstractThis study investigates the energetic investment during spawning of two Mediterranean gorgonians characterized by different reproductive strategies: Corallium rubrum (internal brooder) and Paramuricea clavata (surface brooder). Sexual products (number of oocytes and spermatic sacs) were quantified, and biochemical characteristics (lipid content and free fatty acid content and composition) were determined to investigate the parental energetic investment and demand in reproduction. Results suggested that the majority of the energetic cost was due to reproductive activity (i.e., gametogenesis and spawning). The two species exhibited different life history strategies, with P. clavata investing more energy in reproduction than C. rubrum. However, P. clavata is reproductively more sensitive to inter-annual changes in environmental conditions.

Reproduction, energy storage and metabolic requirements in a mesophotic population of the gorgonian Paramuricea macrospina

This study examined the sexual reproductive cycle, energy storage and metabolic requirements of a Mediterranean gorgonian in a mesophotic ecosystem (~70 m depth). Paramuricea macrospina resulted to be a gonochoric internal brooding species with a 1:1 population sex ratio. Oogenesis lasted ~12–14 months, whereas spermatogenesis was significantly shorter, only lasting 6 months. Fertilization occurred during late summer (August) and larval release occurred during autumn (September–October). The organic matter and total lipid content showed a slight seasonal variability. Stable isotopic composition remained constant throughout the year, reflecting a general stability in gorgonian food sources. Conversely, the free fatty acid composition varied seasonally, reflecting changes in P. macrospina energetic demands probably related to gametogenesis and larval brooding. The reproductive ecology and biochemical composition of P. macrospina significantly differ from shallow coastal gorgonian species, reflecting the higher environmental stability of deeper environments.

Fast growth rate in a young colony of the Mediterranean gorgonian Eunicella singularis

Gorgonian corals are generally slow-growing and long-lived organisms, which can act as structural species in benthic ecosystems ranging from tropical to polar regions. Slow gorgonian growth (up to 2.3 cm year) is particularly evident in deep and polar species (Risk et al. 2002; Martinez-Dios et al. 2016 and references therein), but it has also been reported (up to 2.7 cm year) in temperate species (Coma et al. 1998 and references therein). Conversely, growth rates are generally higher (up to 9.3 cm year) in tropical shallow-water species (Yoshioka and Yoshioka 1991). One of the most abundant gorgonians in coastal benthic communities of the Mediterranean Sea, Eunicella singularis (Esper 1791), has been reported to grow at 2.2–4.52 cm year (Weinberg and Weinberg 1979; Munari et al. 2013). However, a recent observation of a young colony (around 2 years of age) (Fig. 1), which grew on the cable of a mooring in the coastal area of Cap de Creus (42°17′03′′N, 003°17′95′′E) in the northwestern Mediterranean Sea, revealed a minimum growth rate of 7.71 cm year in maximum height, and 29.35 cm year in total branch extension. This demonstrates that, at least during the first years, the temperate E. singularis can grow nearly as fast as the growth rate recorded in tropical gorgonians.

Benthic-Pelagic Coupling: New Perspectives in the Animal Forests

Animal forests all over the world play an essential role in benthic-pelagic coupling processes. These processes can change according to the feeding strategies of benthic species, as well as their extension and biomass. From the oligotrophic coral reefs to the highly seasonal productive Antarctic ecosystems, suspension feeders (the main eco-engineers of the animal forest) have evolved feeding strategies depending on the environmental constraints, which shape their survivorship and partly explain their high biodiversity. In the process of benthic-pelagic coupling, these organisms also have the ability to retain part of the organic and inorganic matter in their long-lived S. Rossi (*) • N. Viladrich Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Barcelona, Spain e-mail: Sergio.rossi@uab.cat; nuria_viladrich@hotmail.com M. Coppari Dipartimento di Scienze della Terra, dell’Ambiente e della Vita (DISTAV), Università degli Studi di Genova, Genoa, Italy e-mail: martysve85@gmail.com # Springer International Publishing Switzerland 2016 S. Rossi (ed.), Marine Animal Forests, DOI 10.1007/978-3-319-17001-5_23-1 1 structures. In this chapter, hypotheses related to benthic-pelagic coupling processes will be presented, along with the newest methodology used to quantify the capacity of animal forests to function as carbon sinks. Although the role of animal forests as carbon sinks is an essential ecosystem service, it has been largely neglected in the conservation models for the majority of marine environments. The importance of food availability (quantity and quality) in suspension feeding animals will be discussed with a new approach based on random pulses of energy input. This approach will help to better understand their nutritional condition and the health status of their populations. Finally, to allow making key evaluations of the influence of animal forests in benthic-pelagic coupling processes and as carbon sinks, this approach will be overlapped with the distribution, density, and population size structure of benthic suspension feeders, obtained through the analysis of video or photo recorded via remotely operated vehicles (ROV). This new approach will be an essential tool for coastal, continental shelves and deep water coral area management and conservation, where animal forests are threatened synergistically by several direct and indirect impacts.