The Lush Fucales Underwater Forests off the Cilento Coast: An Overlooked Mediterranean Biodiversity Hotspot.

Fucales (Phaeophyceae) are ecosystem engineers and forest-forming macroalgae whose populations are declining dramatically. In the Mediterranean Sea, Cystoseira sensu lato (s.l.)-encompassing the genera Cystoseira sensu stricto, Ericaria, and Gongolaria-is the most diverse group, and many species have been shown to be locally extinct in many areas, resulting in a shift toward structurally less complex habitats with the consequent loss of ecosystem functions and services. In this study, we report on the extensive occurrence of healthy and dense marine forests formed by Fucales in the Santa Maria di Castellabate Marine Protected Area in Cilento, Italy (Tyrrhenian Sea, Mediterranean). On a total area of 129.45 ha, 10 Cystoseira s.l. taxa were detected using a combined morphological and molecular approach, with an average cover of more than 70%. One of these taxa has been sequenced for the first time. These findings underline the high ecological value of this area as a hotspot of benthic biodiversity and highlight the importance of marine protected area management and regional monitoring programs to ensure the conservation of these valuable yet fragile coastal ecosystems.

Hexagonal Voronoi pattern detected in the microstructural design of the echinoid skeleton.

Repeated polygonal patterns are pervasive in natural forms and structures. These patterns provide inherent structural stability while optimizing strength-per-weight and minimizing construction costs. In echinoids (sea urchins), a visible regularity can be found in the endoskeleton, consisting of a lightweight and resistant micro-trabecular meshwork (stereom). This foam-like structure follows an intrinsic geometrical pattern that has never been investigated. This study aims to analyse and describe it by focusing on the boss of tubercles-spine attachment sites subject to strong mechanical stresses-in the common sea urchin Paracentrotus lividus. The boss microstructure was identified as a Voronoi construction characterized by 82% concordance to the computed Voronoi models, a prevalence of hexagonal polygons, and a regularly organized seed distribution. This pattern is interpreted as an evolutionary solution for the construction of the echinoid skeleton using a lightweight microstructural design that optimizes the trabecular arrangement, maximizes the structural strength and minimizes the metabolic costs of secreting calcitic stereom. Hence, this identification is particularly valuable to improve the understanding of the mechanical function of the stereom as well as to effectively model and reconstruct similar structures in view of future applications in biomimetic technologies and designs.

Organismal Design and Biomimetics: A Problem of Scale.

Organisms and their features represent a complex system of solutions that can efficiently inspire the development of original and cutting-edge design applications: the related discipline is known as biomimetics. From the smallest to the largest, every species has developed and adapted different working principles based on their relative dimensional realm. In nature, size changes determine remarkable effects in organismal structures, functions, and evolutionary innovations. Similarly, size and scaling rules need to be considered in the biomimetic transfer of solutions to different dimensions, from nature to artefacts. The observation of principles that occur at very small scales, such as for nano- and microstructures, can often be seen and transferred to a macroscopic scale. However, this transfer is not always possible; numerous biological structures lose their functionality when applied to different scale dimensions. Hence, the evaluation of the effects and changes in scaling biological working principles to the final design dimension is crucial for the success of any biomimetic transfer process. This review intends to provide biologists and designers with an overview regarding scale-related principles in organismal design and their application to technical projects regarding mechanics, optics, electricity, and acoustics.

Distribution and Characterization of Deep Rhodolith Beds off the Campania coast (SW Italy, Mediterranean Sea).

Rhodolith beds (RBs) are bioconstructions characterized by coralline algae, which provide habitat for several associated species. Mediterranean RBs are usually located in the mesophotic zone (below 40 m), and thus are frequently remote and unexplored. Recently, the importance and vulnerability of these habitats have been recognized by the European Community and more attention has been drawn to their investigation and conservation. This study reports the results of an extensive monitoring program, carried out within the Marine Strategy Framework Directive (2008/56/EC), in six sites off the Campania coast (Italy, Mediterranean Sea). New insights were given into the distribution, cover, vitality (i.e., live/dead rhodolith ratio), structural complexity, and coralline algae composition of RBs. Remotely operated vehicles (ROV) investigations allowed the description of several RBs, and the discovery of a RB with rhodolith cover >65% offshore the Capri Island. Only two sites (Secchitiello and Punta Campanella) showed a very low mean cover of live rhodoliths (<10%); hence, not being classifiable as RBs. The collected rhodoliths were mostly small pralines (~2 cm), spheroidal to ellipsoidal, with growth-forms ranging from encrusting/warty to fruticose/lumpy. Coralline algae identification revealed a high diversity within each bed, with a total of 13 identified taxa. The genus Lithothamnion dominated all sites, and Phymatolithon calcareum and Lithothamnion corallioides, protected by the Habitats Directive (92/43/EEC), were detected in all RBs.

Physiological response of the coralline alga Corallina officinalis L. to both predicted long-term increases in temperature and short-term heatwave events.

Climate change is leading to an increase of mean sea surface temperatures and extreme heat events. There is an urgent need to better understand the capabilities of marine macroalgae to adapt to these rapid changes. In this study, the responses of photosynthesis, respiration, and calcification to elevated temperature in a global warming scenario were investigated in the coralline alga Corallina officinalis. Algae were cultured for 7 weeks under 4 temperature treatments: (1) control under ambient-summer conditions (C, ~20 °C), (2) simulating a one-week heatwave of 1 °C (HW, Tcontrol+1 °C), (3) elevated temperature (+3, Tcontrol +3 °C), (4) combination of the two previous treatments (HW+3, T+3+1 °C). After exposure at T+3 (up to a Tmax of ~23 °C), respiration and photosynthesis increased significantly. After 5 weeks, calcification rates were higher at elevated temperatures (T+3 and THW+3) compared to Tcontrol, but at the end of the experiment (7 weeks) calcification decreased significantly at those temperatures beyond the thermal optimum (six-fold at T+3, and three-fold at THW+3, respectively). The same trend was noted for all the physiological processes, suggesting that a prolonged exposure to high temperatures (7 weeks up to T+3) negatively affect the physiology of C. officinalis, as a possible consequence of thermal stress. A one-week heatwave of +1 °C with respect to Tcontrol (at THW) did not affect respiration, photosynthesis, or calcification rates. Conversely, a heatwave of 1 °C, when combined with the 3 °C increase predicted by the end of the century (at THW+3), induced a reduction of physiological rates. Continued increases in both the intensity and frequency of heatwaves under anthropogenic climate change may lead to reduced growth and survival of primary producers such as C. officinalis.