Nacella magellanica is an edible limpet that has been consumed since pre-Hispanic times by human populations along the coasts of Patagonia, but studies of its nutritional value and reproduction are not yet available. We investigated the reproductive cycle and the seasonal variation in the nutritional composition (proteins, lipids and carbohydrates) of the whole body of this limpet in order to analyse some aspects of its importance as a formal fishery resource. Throughout a single year, the spawning period extended over all months except June in males, while females spawned from late winter to spring, with an increase from August to November. The nutritional data obtained for N. magellanica are within the ranges of widely consumed species of molluscs, with annual average values of 29.8% proteins, 2.7% lipids and 1.8% carbohydrates. The best nutritional values for human consumption (highest concentration of proteins, body weight), avoiding the reproductive period, were found in April but taking into account the minimum size of capture. Our results are useful for increasing the policies aimed at managing this abundant edible limpet as a formal resource, since it is widely consumed in southern South America.

Understanding phenotypic plasticity of species at different spatial scales is vital in the current context of an increasing pace of environmental changes. Through this knowledge, it is possible to predict their potential to adapt and/or evolve in face of new environmental conditions such as climate change, and/or to understand their ecological range expansion. In Patagonian rocky salt-marshes, one of the most abundant invertebrate species is the scorched mussel Perumytilus purpuratus. In this system, this mussel can be found inhabiting both vegetated and non-vegetated patches, which differ in critical environmental conditions. We performed a field study evaluating whether mussels growing in vegetated patches differ in shell shape from those growing in adjacent non-vegetated patches. We sampled individuals from both patch types and assessed their shell shape and size using geometric morphometrics. The results showed that mussels from vegetated patches had shells that were more dorsoventrally expanded, anterodorsally restricted and globose in shape than those from non-vegetated patches, which showed the opposite traits resulting in a more elongated shell. The differences found could be driven by the different conditions of temperature, desiccation rate, wave action and population density to which mussels are exposed in each patch type. These results revealed the striking phenotypic plasticity of shell form of this native species at a fine-grained scale, which could be one of the explanations for its success in its ecological range expansion.