A decade later, reviewing floating marine debris in Northern Chilean Patagonia.

Floating marine debris (FMD) were abundantly reported in the Northern Chilean Patagonia in 2009 where sea-based activities (mussel and salmon aquaculture) are responsible for most of them. Identifying the sources of FMD is important to take the necessary actions to diminish their abundance. In 2019 eleven transects were opportunistically conducted to evaluate the abundance, spatial distribution and composition of FMD in the same area, and to compare them with the previous study using the same methodology. FMD identified were classified into the same six categories from the previous study, however "Others" category were now the dominant one indicating that new pollutants have been increasing during the last decade. Inside the "others" category, plastics buoy and other floating devices, that normally are used by the salmon aquaculture, were the main items. Similarly than the previous study, styrofoam and domestic plastics were also the other most abundant items. In general, also, an increase in abundance compared with the previous study was found. The highest abundances were similarly found in the "Golfo de Corcovado" zone ranging from 50 to 230 items km-2. Our results, as well as the previous study, confirm that sea-based activities are still responsible for the FMD found in the Northern Patagonia. To avoid the origin of this contamination it is urgent to implement public policies that effectively reduce FMD, and hold the aquaculture industries responsible.

Exposure to artificial light at night (ALAN) alters RNA:DNA ratios in a sandy beach coleopteran insect.

Coastal habitats worldwide, including sandy beaches, are becoming increasingly exposed to Artificial Light at Night (ALAN). Despite the spread of this global stressor, research assessing ALAN potential impacts remain scarce, particularly at the molecular level. This study addressed this gap by assessing the influence of ALAN on the physiological condition of the sandy beach insect Phalerisida maculata Kulzer (Coleoptera, Tenebrionidae). RNA:DNA ratios were used here as a proxy of the insect's nutritional condition in laboratory trials that lasted 20 d. Insects were exposed to two representative ALAN conditions (either 60 or 120 lx) and compared with those maintained in a natural daylight/night cycle (0 lx at nigth; control). After the trial, organisms from each treatment were frozen in liquid nitrogen and standard protocols were followed to estimate RNA, DNA and RNA:DNA ratios. Estimates of RNA:DNA ratios from insects maintained in control conditions were significantly higher (P < 0.05) than those from insects exposed to ALAN. The reduced nutritional condition of insects exposed to light pollution is explained by the lower in situ biosynthetic capacity in these organisms resulting from a reduction in their feeding. ALAN likely altered P. maculata normal locomotor activity, which takes place primarily at night, forcing the insects to remain buried in the sand for extended periods of time. As ALAN continues to spread along coastlines worldwide, there is a likelihood of growing impacts on these and other species living on sandy beaches and other coastal habitats.

Role of temperature and carbonate system variability on a host-parasite system: Implications for the gigantism hypothesis.

Biological interactions and environmental constraints alter life-history traits, modifying organismal performances. Trematode parasites often impact their hosts by inducing parasitic castration, frequently correlated with increased body size in the host (i.e., gigantism hypothesis), which is postulated to reflect the re-allocation of energy released by the reduction in the reproductive process. In this study, we compared the effect of a trematode species on shell size and morphology in adult individuals of the intertidal mussels Perumytilus purpuratus (>20 mm) collected from two local populations of contrasting environmental regimes experienced in central-southern Chile. Our field data indicates that in both study locations, parasitized mussels evidenced higher body sizes (shell length, total weight and volume) as compared with non-parasitized. In addition, parasitized mussels from the southern location evidenced thinner shells than non-parasitized ones and those collected from central Chile, suggesting geographical variation in shell carbonate precipitation across intertidal habitats of the Chilean coast. In laboratory conditions, mussels collected from a local population in central Chile were exposed to two temperature treatments (12 and 18 °C). Parasitized mussels showed higher growth rates than non-parasitized, regardless of the seawater temperature treatments. However, the metabolic rate was not influenced by the parasite condition or the temperature treatments. Our field and laboratory results support the parasite-induced gigantism hypothesis, and suggest that both the thermal environment and geographic location explain only a portion of the increased body size, while the parasitic condition is the most plausible factor modulating the outcome of this host-parasite interaction.

First detection of plastic microfibers in a wild population of South American fur seals (Arctocephalus australis) in the Chilean Northern Patagonia.

The dramatic increase of microplastics (plastic fragments <5 mm) in marine environments is a problem that has attracted public attention globally. Within the different types of microplastics, microfibres are the least studied (size <1 mm). We examined 51 female scats from a population in Northern Patagonia. Our results showed no presence of microplastic particles, however 67% of them showed a remarkable abundance of microfibers, which until now had only been reported in animals fed in captivity. As a result of this work we propose that the examination of scats from South American Fur Seal and also other pinnipeds could be an efficient tool to monitor environmental levels of microfibres and maybe microplastics in the environment due to the easy recognition of the animals and their scats.

Coastal debris survey in a Remote Island of the Chilean Northern Patagonia.

Global marine litter pollution is increasing dramatically, and oceanic islands are one of the most vulnerable ecosystems due to their high debris accumulation rate compared to continental sites. Remote areas, such as inhabited islands, represent a perfect study case to track marine debris sources, due to the assumed low rates of local production of debris. Guafo Island is one of the largest islands of the Chilean Northern Patagonia and is considered a remote zone. The accessible coast of Guafo Island was monitored during four austral summers revealing higher levels of marine debris accumulation than continental Chile. Plastic was the most abundant type of debris constituting 50% of the total litter monitored. Our results suggest that most of the plastic identified is likely to be related to local fisheries activities. Mitigation measures including collaboration among fishing communities and scientists could contribute to reduce the coastal debris pollution in remote areas.

Intertidal pool fish Girella laevifrons (Kyphosidae) shown strong physiological homeostasis but shy personality: The cost of living in hypercapnic habitats.

Tide pools habitats are naturally exposed to a high degree of environmental variability. The consequences of living in these extreme habitats are not well established. In particular, little it is known about of the effects of hypercanic seawater (i.e. high pCO2 levels) on marine vertebrates such as intertidal pool fish. The aim of this study was to evaluate the effects of increased pCO2 on the physiology and behavior in juveniles of the intertidal pool fish Girella laevifrons. Two nominal pCO2 concentrations (400 and 1600µatm) were used. We found that exposure to hypercapnic conditions did not affect oxygen consumption and absorption efficiency. However, the lateralization and boldness behavior was significantly disrupted in high pCO2 conditions. In general, a predator-risk cost of boldness is assumed, thus the increased occurrence of shy personality in juvenile fishes may result in a change in the balance of this biological interaction, with significant ecological consequences.

Effect of UV radiation on habitat selection by Girella laevifrons and Graus nigra (Kyphosidae).

The effect of UV radiation on habitat use of two species of intertidal fishes that inhabit the same pools but exhibit different activity levels and diets was measured: the highly active omnivorous Girella laevifrons and the cryptic carnivorous Graus nigra. Individuals of each species were acclimated to a tank divided in three sections with different illumination; no light (NL), ultraviolet light (UV) and white light (WL), and the time spent and number of visits to each section were recorded. Although both species preferred the NL section, G. laevifrons spent more time in UV and less time in WL compared with G. nigra; G. laevifrons also displayed higher number of visits to UV, suggesting a different tendency in space use in response to UV exposure in intertidal fishes.

Can upwelling signals be detected in intertidal fishes of different trophic levels?

For intertidal fishes belonging to three species, the herbivore Scartichthys viridis (Blenniidae), the omnivore Girella laevifrons (Kyphosidae) and the carnivore Graus nigra (Kyphosidae), mass and body size relationships were higher in individuals from an upwelling zone compared with those from a non-upwelling zone. RNA:DNA were higher in the herbivores and omnivores from the upwelling zone. Higher biomass and RNA:DNA in the upwelling intertidal fishes may be a consequence of an increased exposure to higher nutrient availability, suggesting that increased physiological conditioning in vertebrates from upwelling areas can be detected and measured using intertidal fishes of different trophic levels.