Monitoring the Ocean with Cephalopods

Projected near-future CO2 levels increase activity and alter defensive behaviours in the tropical squid Idiosepius pygmaeus
Blake L. Spady,Sue-Ann Watson1,Tory J. Chase1,Philip L. Munday 2014 (full report)

ABSTRACT
Carbon dioxide (CO2) levels projected to occur in the oceans by the end of this century cause a range of behavioural effects in fish, but whether other highly active marine organisms, such as cephalopods, are similarly affected is unknown. We tested the effects of projected future CO2 levels (626 and 956 µatm) on the behaviour of male two-toned pygmy squid, Idiosepius pygmaeus. Exposure to elevated CO2 increased the number of active individuals by 19–25% and increased movement (number of line-crosses) by nearly 3 times compared to squid at present-day CO2. Squid vigilance and defensive behaviours were also altered by elevated CO2 with >80% of individuals choosing jet escape responses over defensive arm postures in response to a visual startle stimulus, compared with 50% choosing jet escape responses at control CO2. In addition, more escape responses were chosen over threat behaviours in body pattern displays at elevated CO2 and individuals were more than twice as likely to use ink as a defence strategy at 956 µatm CO2, compared with controls. Increased activity could lead to adverse effects on energy budgets as well as increasing visibility to predators. A tendency to respond to a stimulus with escape behaviours could increase survival, but may also be energetically costly and could potentially lead to more chases by predators compared with individuals that use defensive postures. These results demonstrate that projected future ocean acidification affects the behaviours of a tropical squid species.
 
Development of Embryonic Market Squid, Doryteuthis opalescens, under Chronic Exposure to Low Environmental pH and [O2]
Michael O. Navarro, Garfield T. Kwan, Olga Batalov, Chelsea Y. Choi, N. Tessa Pierce, Lisa A. Levin2016 PLOS One Full Article

Abstract The market squid, Doryteuthis opalescens, is an important forage species for the inshore ecosystems of the California Current System. Due to increased upwelling and expansion of the oxygen minimum zone in the California Current Ecosystem, the inshore environment is expected to experience lower pH and [O2] conditions in the future, potentially impacting the development of seafloor-attached encapsulated embryos. To understand the consequences of this co-occurring environmental pH and [O2] stress for D. opalescens encapsulated embryos, we performed two laboratory experiments. In Experiment 1, embryo capsules were chronically exposed to a treatment of higher (normal) pH (7.93) and [O2] (242 μM) or a treatment of low pH (7.57) and [O2] (80 μM), characteristic of upwelling events and/or La Niña conditions. The low pH and low [O2] treatment extended embryo development duration by 5–7 days; embryos remained at less developed stages more often and had 54.7% smaller statolith area at a given embryo size. Importantly, the embryos that did develop to mature embryonic stages grew to sizes that were similar (non-distinct) to those exposed to the high pH and high [O2] treatment. In Experiment 2, we exposed encapsulated embryos to a single stressor, low pH (7.56) or low [O2] (85 μM), to understand the importance of environmental pH and [O2] rising and falling together for squid embryogenesis. Embryos in the low pH only treatment had smaller yolk reserves and bigger statoliths compared to those in low [O2] only treatment. These results suggest that D. opalescens developmental duration and statolith size are impacted by exposure to environmental [O2] and pH (pCO2) and provide insight into embryo resilience to these effects.
 
Metal accumulations in different tissues of cuttlefish (Sepia officinalis L., 1758) in the Eastern Mediterranean coasts of Turkey
Önder Duysak 2017 (Springer subscription)

Abstract
In this study, metal concentration levels (Cd, Co, Cr, Ni, and Pb) were investigated in the gill, hepatopancreas, ovary, testis, and mantle of the male and female cuttlefish Sepia officinalis in various stations (Iskenderun, Antalya, Kas, Gazipasa, and Anamur) in Mediterranean coasts of Turkey. Hepatopancreas tissue was a better indicator in terms of heavy metal concentration compared to the other tissues. In general, Cd, Co, Cr, Ni, and Pb accumulation for the male was found more than that of the female, whereas Cd and Ni accumulation was found higher in the female. There was a relationship among the metals in the form of Co > Pb > Ni > Cd > Cr in the mantle tissue. The Pb concentration over the recommended limits was found in cuttlefish of Anamur, Antalya, and Iskenderun stations.
 
On the way for detecting and quantifying elusive species in the sea: The Octopus vulgaris case study
Q. Mauvisseau, M. Parrondo, M.P. Fernández, L. García, J.L. Martínez, E. García-Vázquez, Y.J. Borrell 2017 (subscription Science Direct)
Abstract
Environmental DNA (eDNA) can be a powerful method for assessing the presence and the distribution of aquatic species. We used this tool in order to detect and quantify eDNA from the elusive species Octopus vulgaris, using qPCRs (SybrGreen protocol). We designed species-specific primers, and set up an experimental aquarium approach to validate the new molecular tool in different controlled conditions. Field validation was conducted from sea water samples taken from 8 locations within an octopus fishery area in the Cantabrian Sea during February–March 2016. A significant positive correlation between the total biomass (g of O. vulgaris within thanks) and the amount of O. vulgaris eDNA detected (p-value = 0.01261) was found in aquarium experiments. The species was also detected by PCR in 7 of the 8 water samples taken at sea, and successfully quantified by qPCR in 5 samples. This preliminary study and innovative method opens very promising perspectives for developing quick and cheap tools for the assessment of O. vulgaris distribution and abundance in the sea. The method could help in a close future for quantifying unseen and elusive marine species, thus contributing to establish sustainable fisheries.
 
Predatory strategies and behaviours in cephalopods are altered by elevated CO2
BL Spady (@DarkwingedDuck), PL Munday, SA Watson - Global Change Biology
Abstract
There is increasing evidence that projected near-future carbon dioxide (CO2) levels can alter predator avoidance behaviour in marine invertebrates, yet little is known about the possible effects on predatory behaviours. Here we tested the effects of elevated CO2 on the predatory behaviours of two ecologically distinct cephalopod species, the pygmy squid, Idiosepius pygmaeus, and the bigfin reef squid, Sepioteuthis lessoniana. Both species exhibited an increased latency to attack and altered body-pattern choice during the attack sequence at elevated CO2. I. pygmaeus also exhibited a 20% decrease in predation rate, an increased striking distance, and reduced preference for attacking the posterior end of prey at elevated CO2. Elevated CO2 increased activity levels of S. lessoniana comparable to those previously shown in I. pygmaeus, which could adversely affect their energy budget and increase their potential to be preyed upon. The effects of elevated CO2 on predatory behaviours, predation strategies and activity levels of cephalopods reported here could have far-reaching consequences in marine ecosystems due to the ecological importance of cephalopods in the marine food web.
 
Reproductive performance of Octopus maya males conditioned by thermal stress
Laura López-Galindo, Clara Galindo-Sánchez, Alberto Olivares, Omar Hernando Avila-Poveda, Fernando Díaz, Oscar E. Juárez, Fabiola Lafarga, Jordi Pantoja-Pérez, Claudia Caamal-Monsreal, Carlos Rosas 2018 (full article)

Abstract
Observations of wild male O. maya suggest that temperatures below 27 °C favour their reproductive performance. From these observations we hypothesize that, as in females, the temperature modulates the reproductive performance of adult O. maya males. The study aimed to evaluate the physiological condition, reproductive success, and histological damage in testis of male O. maya exposed to thermal stress, to determine the implications of ocean warming over their reproductive performance. High temperatures (28–30 °C) negatively affect the growth and health of male O. maya. In octopuses maintained at 30 °C, as a consequence of the thermal stress we observed an increment in the haemocytes number, a reduction in the oxygen consumption rate, and an inflammatory process in the testis. The number of spermatozoa per spermatophore was not affected by temperature, but higher spermatophores production was observed at 30 °C. The paternity analysis showed that the offspring had multiple paternity with an average of 10 males contributing in a single spawn. The paternal contribution was affected by temperature with high, medium, or no paternal contribution in animals maintained at 24 °C (control group), 28 °C and 30 °C, respectively. The temperatures from 28 °C to 30 °C deeply affected the reproductive performance of Octopus maya males, suggesting that, as embryos, reproductive performance of adult males of this octopus species can be used as a tool for monitoring thermal changes in Yucatán Peninsula, located at the entrance of Gulf of Mexico.
 
Editorial: The Digestive Tract of Cephalopods: At the Interface Between Physiology and Ecology
Giovanna Ponte, Eduardo Almansa, Paul L. R. Andrews 2018 (collection of paper topics with links)

The collection of papers included in this Research Topic represents the outcome of some of the activities of the COST Action FA1301, CephsInAction. It emerged from a series of presentations delivered during a workshop in Cascais (Portugal; November 24th, 2015), and from the research activities carried out during Short Term Scientific Missions supported through the COST Action FA1301. The overall aim is to fill some lacunae in knowledge of the digestive tract of cephalopod molluscs. In contrast to other areas of cephalopod biology such as the central nervous system and behavior (e.g., Marini et al., 2017; Nakajima et al.; O'Brien et al.; Shigeno et al.) and the visual system (see Hanke and Osorio), relatively little research has been done on this topic during the last 30 years.
 

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