Performance of the long-snouted seahorse, Hippocampus guttulatus, under warming conditions

Abstract

Temperature is a determinant cue for several behavioral, physiological, and metabolic processes in fish, which occur within a range set to optimize species fitness. Understanding how ocean warming will impact species, at individual and population levels, is, therefore, of utmost relevance for management and conservation purposes. This knowledge assumes particular relevance when it comes to species with unique life history traits that experience multiple threats, such as seahorses. This study aimed to assess the effects of warming on growth, feed intake, and behavioral patterns of the long-snouted seahorse, Hippocampus guttulatus. Fish were collected, before the breeding season, in the Sado estuary, Portugal, and subsequently exposed for an 8-week period to three different temperatures: 17°C, 20°C, and 24°C. Three times a week, behavioral observations were performed. Feed intake was measured every day and individuals were weighed once a week. Results indicate differences in behavioral responses of seahorses exposed to increasingly warming conditions. Under extreme temperature conditions (24°C), fish were more active, and fed more, but this increment of energy through feeding did not translate into increased growth in weight. Altogether, these results indicate that Sado’s population of H. guttulatus may become under thermal stress when exposed, for a long term, to warming conditions that are expected to occur by the end of the century.

Chemical Survey and Risk Assessment of 56 Pesticides in the Sado River Estuary (Iberian Peninsula, Portugal)

“…Rising levels of nutrients, eutrophication, pesticides and biocides, heavy metals, organotins, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and even natural and pharmaceutical estrogens have been reported in the Sadoassociated ecosystems during recent decades [15,17,18]. These pollutants and other human activities, such as shipping and global warming, have promoted severe pressure and continuous species' declines over the past decades (well-registered for a few, such as the snouted seahorse, bottlenose dolphin, and, recently, waterbirds) [19][20][21][22]. The Sado estuary is a legally defined natural reserve covering approximately 23,160 ha [14] with indigenous vegetation and perfect habitats for many aquatic species, such as molluscs, crustaceans, fish, and the emblematic bottlenose dolphin (Tursiops truncates).…”