Mysterious Morphology: An Investigation of the Octopus Keel and Its Association with Burrowing.

The octopus keel is a trait that has been hypothesized to be connected with burrowing in octopuses, but has never been explored in any detail. We investigated the association between these two traits using two approaches. First, we examined the phylogenetic correlation between the presence of a keel and known burrowing behavior in cirrate octopuses. Second, burrowing and non-burrowing captive Muusoctopus leioderma were evaluated for keel prominence to determine whether the keel is lost more rapidly in non-burrowing individuals. Pagel's test for the coevolution of binary characteristics showed the model of best fit for the resulting phylogenetic tree to be one of evolutionary interdependence, and that non-burrowing Muusoctopus leioderma lost their keels over time, while burrowing individuals maintained their keels. Together, these results indicate the keel may be a trait associated with burrowing in octopuses.

The Open acidification Tank Controller: An open-source device for the control of pH and temperature in ocean acidification experiments.

Ocean acidification is the process by which the increase in atmospheric CO2 causes a corresponding increase in seawater CO2 and results in lowering the seawater pH. While this process is likely to have substantial impacts on marine ecosystems, research into the effect of ocean acidification has been limited by the high costs of quality tools to perform ocean acidification treatments in the lab. The Open Acidification Tank Controller is designed to reduce the cost of ocean acidification research by providing a device that can monitor and control pH and temperature of aquaria as well as or better than commercially available research-grade devices, but for less than $250 USD per aquarium. The device is centered around an Arduino Mega 2560 and is assembled into a 3D printed housing. It monitors pH using a BNC glass pH probe and temperature using a three-wire waterproof PT100 temperature sensor. The Open Acidification Tank Controller also features web-based parameter reporting, and data storage to a micro-SD card. This device can hold aquarium pH and temperature at given setpoints, ramp between two values over a user-defined time period, or produce a sine-wave fluctuation in values.

The Open-source Camera Trap for Organism Presence and Underwater Surveillance (OCTOPUS).

This Open-source Camera Trap for Organism Presence and Underwater Surveillance (OCTOPUS) was designed to operate as a motion activated camera trap, deployable at depths of up to 800 ft for ∼72 h deployments. The core components of the OCTOPUS are built off a Raspberry Pi 3B+ with a custom PCB hat which operates a strobe lighting system and a high definition Arducam camera. When an appropriate threshold of motion is detected, the OCTOPUS captures a high-definition image of the subject. Field trials for this system demonstrated its use for cryptic benthic organisms, specifically small octopus (Octopus rubescens). The OCTOPUS collected data on several species allowing the observation and quantification of interspecific and conspecific interactions. This system unlocks the potential of autonomous underwater data collection for a wide range of applications, from species specific observations to large scale ecological assessments.

Synergistic and antagonistic interactions of oxybenzone and ocean acidification: new insight into vulnerable cellular processes in non-calcifying anthozoans.

Cnidarians face significant threats from ocean acidification (OA) and anthropogenic pollutants such as oxybenzone (BP-3). The convergence of threats from multiple stressors is an important area to investigate because of potential significant synergistic or antagonistic interactions. Real-time quantitative PCR was performed to characterize the expression profiles of twenty-two genes of interest (GOI) in sea anemones (Exaiptasia diaphana) exposed to one of four treatments: 1) 96 h of OA conditions followed by a 4 h exposure to 20 ppb BP-3; 2) Exposure to 4 h 20 ppb BP-3 without 96 h of OA; 3) Exposure to 96 h of OA alone; or 4) laboratory conditions with no exposure to BP-3 and/or OA. These 22 GOIs represent cellular processes associated with proton-dependent transport, sodium-dependent transport, metal cation binding/transport, extracellular matrix, amino acid metabolism/transport, immunity, and/or steroidogenesis. These 22 GOIs provide new insight into vulnerable cellular processes in non-calcifying anthozoans exposed to OA and BP-3. Expression profiles were categorized as synergistic, antagonistic, or additive of BP-3 in the presence of OA. Two GOIs were synergistic. Fifteen GOIs were antagonistic and the remaining five GOIs were additive in response to BP-3 in acidified seawater. A subset of these GOIs appear to be candidate biomarkers for future in situ investigations. In human health, proton-dependent monocarboxylate transporters (MCTs) are promising pharmacological targets and recognized as potential biomarkers. By comparison, these same MCTs appear to be targets of xenobiotic chemical pollutants in cnidarian physiology. In the presence of BP-3, a network of collagen synthesis genes are upregulated and antagonistic in their expression profiles. Cytochrome b561 is a critical protein required for collagen synthesis and in silico modeling demonstrates BP-3 binds in the pocket of cytochrome b561. Understanding the underlying molecular mechanisms of "drug-like" compounds such as BP-3 may lead to a more comprehensive interpretation of transcriptional expression profiles. The collective antagonistic responses of GOIs associated with collagen synthesis strongly suggests these GOIs should be considered candidate biomarkers of effect. GOIs with synergistic and additive responses represent candidate biomarkers of exposure. Results show the effects of OA and BP-3 are interactive with respect to their impact on cnidarians. This investigation offers mechanistic data that supports the expression profiles and underpins higher order physiological responses.

Bathyal octopus, Muusoctopus leioderma, living in a world of acid: First recordings of routine metabolic rate and critical oxygen partial pressures of a deep water species under elevated pCO2.

Elevated atmospheric CO2 as a result of human activity is dissolving into the world's oceans, driving a drop in pH, and making them more acidic. Here we present the first data on the impacts of ocean acidification on a bathyal species of octopus Muusoctopus leioderma. A recent discovery of a shallow living population in the Salish Sea, Washington United States allowed collection via SCUBA and maintenance in the lab. We exposed individual Muusoctopus leioderma to elevated CO2 pressure (pCO2) for 1 day and 7 days, measuring their routine metabolic rate (RMR), critical partial pressure (P crit ), and oxygen supply capacity (α). At the time of this writing, we believe this is the first aerobic metabolic data recorded for a member of Muusoctopus. Our results showed that there was no change in either RMR, P crit or α at 1800 µatm compared to the 1,000 µatm of the habitat where this population was collected. The ability to maintain aerobic physiology at these relatively high levels is discussed and considered against phylogeny and life history.

Open Source Solutions in Experimental Design: An Introduction to the Symposium.

The Open Science movement has increased dramatically in popularity with deserved calls to action around transparency, access to resources, and inclusion in our field. However, its practical applications within experimental design have been slow to uptake, with researchers unsure where to even start with the dizzying array of open source hardware and software solutions available. The perceived time investment and unknown cost, especially in implementing open source hardware, has stagnated the implementation of inexpensive experimental solutions, but we sought to increase awareness to lower the barrier to participation in this space. While there are countless technical and financial advantages to integrating open source solutions into every biologist's experimental design, we put an emphasis on the "people" part of the equation in our symposium. This symposium championed innovative experimental designs by early career Society for Integrative and Comparative Biology researchers across all fields of biology, from plants to animals, in the lab or in the field, or even virtually engaging with the public and students. The Open Science movement operates within community norms that champion transparency, continuous development, and collaboration. These values are congruent with the priorities of reducing barriers to participation in science, and we hope our symposium's collection of open source solutions encourages readers to adopt these or other innovative designs into their own experimentation.

Den-Associated Behavior of Octopus rubescens Revealed by a Motion-Activated Camera Trap System.

Dens are a crucial component of the life history of most shallow water octopuses. However, den usage dynamics have only been explored in a few species over relatively short durations, and Octopus rubescens denning behavior has never been explored in situ. We built four underwater camera traps to observe the behavior of O. rubescens in and around their dens. To distinguish individuals, octopuses were captured and given a unique identifiable visible implant elastomer tag on the dorsal side of their mantle. After being tagged and photographed, each octopus was released back to its original capture site within its original den bottle. The site is unique in that octopuses reside almost exclusively in discarded bottles, therefore aiding in locating and monitoring dens. Motion-activated cameras were suspended in a metal field-of-view above bottle dens of released octopuses to observe den-associated behaviors. Cameras were regularly retrieved and replaced to allow continuous monitoring of den locations in 71 h intervals for over a month. We found that O. rubescenswas primarily active during the day and had frequent interactions with conspecifics (other members within the species). We also found that rockfish and red rock crabs tended to frequent den locations more often when octopuses were not present, while kelp greenling both visited dens more frequently and stayed longer when octopuses were present. Our results, demonstrate the utility of motion-activated camera traps for behavioral and ecological studies of nearshore mobile organisms.

Providing interactive and field laboratories while teaching university marine biology classes in an era of COVID-19.

An entirely online upper-division university marine invertebrates course modeled after a field experience-intensive course that also provided interaction with live animals and research experience was offered at Rosario Beach Marine Laboratory in the summer of 2020. We describe online methods we used for providing field experiences to students participating online, as well as a workstation and interactive method for identification and detailed anatomical examination of live macroinvertebrates with students. Students were also involved as active participants in a field research project. Nearly all of the equipment involved is inexpensive or readily available in most university biology laboratories or classrooms.

Impact of Short- and Long-Term Exposure to Elevated Seawater Pco2 on Metabolic Rate and Hypoxia Tolerance in Octopus rubescens.

AbstractMuch of the CO2 released by human activity into the atmosphere is dissolving into the oceans, making them more acidic. In this study we provide the first data on the short- and long-term impacts of ocean acidification on octopuses. We measured routine metabolic rate (RMR) of Octopus rubescens at elevated CO2 pressure (Pco2) with no prior acclimation and 1 or 5 wk of acclimation and critical oxygen pressure (Pcrit) after 5 wk of acclimation. Our results show that with no prior acclimation, octopuses had significantly higher RMRs in 1,500-µatm Pco2 environments than octopuses in 700- or 360-µatm environments. However, after both 1 and 5 wk of acclimation there was no significant difference in RMRs between octopuses at differing Pco2, indicating that octopuses acclimated rapidly to elevated Pco2. In octopuses acclimated for 5 wk at 1,500 µatm Pco2, we observed impaired hypoxia tolerance, as demonstrated by a significantly higher Pcrit than those acclimated to 700 µatm Pco2. Our findings suggest that O. rubescens experiences short-term stress in elevated Pco2 but is able to acclimate over time. However, while this species may be able to acclimate to near-term ocean acidification, compounding environmental effects of acidification and hypoxia may present a physiological challenge for this species.