Reduction of small-prey capture rate and collective predation in the bleached sea anemone Exaiptasiadiaphana

Cnidarians may dominate benthic communities, as in the case of coral reefs that foster biodiversity and provide important ecosystem services. Polyps may feed by predating mesozooplantkon and large motile prey, but many species further obtain autotrophic nutrients from photosymbiosis. Anthropogenic disturbance, such as the rise of seawater temperature and turbidity, can lead to the loss of symbionts, causing bleaching. Prolonged periods of bleaching can induce mortality events over vast areas. Heterotrophy may allow bleached cnidarians to survive for long periods of time. We tested the reinforcement of heterotrophic feeding of bleached polyps of Exaiptasia diaphana fed with both small zooplantkon and large prey, in order to evaluate if heterotrophy allows this species to compensate the reduction of autotrophy. Conversely to expected, heterotrophy was higher in unbleached polyps (+54% mesozooplankton prey and +11% large prey). The increase of heterotrophic intake may not be always used as a strategy to compensate autotrophic depletion in bleached polyps. Such a resilience strategy might be more species-specific than expected.

Differential Bioaccumulation of Trace Elements and Rare Earth Elements in the Muscle, Kidneys, and Liver of the Invasive Indo-Pacific Lionfish (Pterois spp.) from Cuba

The Indo-Pacific lionfish is a saltwater fish that inhabits the Red Sea waters and the Indian and Pacific oceans; it is an invasive species in the western Atlantic and was recently introduced into the local diet in the USA, Central and South America, and the Caribbean with the aim of controlling the invasion of this species. Due to its predatory nature, it tends to bioaccumulate metals and other contaminants via the marine food web and could thus constitute a suitable species for monitoring aquatic ecosystems. The presence and distribution of 23 trace elements and 16 rare earth elements (REEs) were investigated by inductively coupled plasma-mass spectrometry (ICP-MS) in the muscle, liver, and kidneys of lionfish from Cuba. Significant differences in metal concentrations were found in the different fish organs. The liver and kidneys registered the highest concentrations for most trace elements and for ΣREE, thus demonstrating that they are effective bioindicators of possible pollution on the environment in which fish live, and assuming great importance in the choice of early biomonitoring. Trace element concentrations in the muscle are instead of crucial interest for consumer safety. The limits set by EU regulations and Cuban guidelines for Cd and Pb in fish muscle were never exceeded, suggesting that lionfish from Cuba could therefore represent a good source of minerals and proteins for the local population. Graphical abstract.

Feathers of Humboldt penguin are suitable bioindicators of Rare Earth Elements

Rare earth elements (REEs), also called lanthanides, are emerging contaminants worldwide, due to their unique physical and chemical characteristics that make them essential in a variety of industrial applications. However, there is still a gap in the knowledge of occurrence and accumulation of REEs in biota, and no investigations have yet been performed in penguin feathers, which have already been widely utilized as a non-invasive tool for the biomonitoring of trace elements. The concentrations of 16 REEs were investigated in a colony of Humboldt penguins (Spheniscus humboldti) housed at the Acquario di Cattolica (Italy). Multielement determination of REEs was performed by an Inductively Coupled Plasma-Mass Spectrometer after a microwave digestion of feathers. As this colony lives indoors in a controlled environment, it was the ideal choice for studying lanthanide occurrence in penguin feathers. Since there is a strict link between metal levels in feathers and the diet of penguins, their food (capelin) was also tested for REEs. Chondrite normalized values revealed the same pattern for REEs in feathers and fish, but REE concentrations were an order of magnitude higher in penguin feathers, demonstrating the suitability of this tissue as a bioindicator of REEs.

Spinal deformity in a sandtiger shark, Carcharias taurus Rafinesque: a clinical-pathological study

The present study investigated spinal deformity in a captive sandtiger shark and describes the clinical and histopathological features of the lesion. Clinically, the shark presented a marked spinal curvature in the region between the pectoral girdle and cranial dorsal fin. Radiographic studies revealed scoliosis and kyphosis of the vertebral column with a modification of the basic structure of five vertebrae. Post-mortem examination confirmed the results of radiographic studies and histological examination showed remodelling and cartilaginous proliferation of the vertebral bodies together with necrosis, haemorrhage and signs of a local chronic inflammatory response extending to the surrounding muscle. Different aetiologies are proposed and discussed but nutritional imbalance (dietary vitamin deficiency) and/or traumatic injury are considered the most likely contributing factors.