Showing papers in "The Biological Bulletin in 2021"

Flocculation of PVC Microplastic and Fine-Grained Cohesive Sediment at Environmentally Realistic Concentrations

Abstract: Microplastic particles have become ubiquitous in aquatic environments and can be found in large numbers in riverine, estuarine, and marine settings at the surface of water, in suspension, a

Variability in Toxicity of Plastic Leachates as a Function of Weathering and Polymer Type: A Screening Study with the Copepod Nitocra spinipes

Abstract: Variability in toxicity of plastic leachates as a function of weathering and polymer type: A screening study with Nitocra spinipes

Efficacy of Microplastic Separation Techniques on Seawater Samples: Testing Accuracy Using High-Density Polyethylene.

Abstract: Microplastic contamination of the marine environment has been reported globally. Its pervasiveness has highlighted the importance of accurate quantification to enable comparability within and between different environmental matrices. The potential efficacy of different methods to separate microplastics from their environmental sample matrix, however, is rarely validated. In this study, we examine the effects of four commonly used separation methods for seawater samples, namely, visual separation, density flotation, acidic digestion, and enzymatic digestion, using high-density polyethylene as our model microplastic. For each separation method, clarification efficiencies of the sample matrix, spiked recovery of high-density polyethylene microparticles, and potential changes in the chemical and physical characteristics of high-density polyethylene were assessed. High, albeit variable, recovery rates (>83%) of high-density polyethylene microparticles were achieved across all methods. Concentrated nitric acid was most effective at eliminating biological material from seawater samples. No apparent physical (i.e., length or color) or chemical changes due to separation treatments were observed in recovered high-density polyethylene microparticles, with the one exception that enzymatic digestion obscured polymer identification of high-density polyethylene. Our findings highlight the need to determine and report on the accuracy of separation methods for different polymer types and specific environmental sample matrices to ensure accurate quantification of marine microplastic contamination.

Selection Experiments in the Sea: What Can Experimental Evolution Tell Us About How Marine Life Will Respond to Climate Change?

Abstract: Rapid evolution may provide a buffer against extinction risk for some species threatened by climate change; however, the capacity to evolve rapidly enough to keep pace with changing environ...

The Crustacean Antennule: A Complex Organ Adapted for Lifelong Function in Diverse Environments and Lifestyles

Abstract: The crustacean first antenna, or antennule, has been an experimental model for studying sensory biology for over 150 years. Investigations have led to a clearer understanding of the functional organization of the antennule as an olfactory organ but also to a realization that the antennule is much more than that. Across the Crustacea, the antennules take on many forms and functions. As an example, the antennule of reptantian decapods has many types of sensilla, each with distinct structure and function and with hundreds of thousands of chemosensory neurons expressing hundreds of genes that code for diverse classes of receptor proteins. Together, these antennular sensilla represent multiple chemosensory pathways, each with its own central connections and functions. The antennule also has a diversity of sensors of mechanical stimuli, including vibrations, touch, water flow, and the animal's own movements. The antennule likely also detects other environmental cues, such as temperature, oxygen, pH, salinity, and noxious stimuli. Furthermore, the antennule is a motor organ-it is flicked to temporally and spatially sample the animal's chemo-mechanical surroundings-and this information is used in resolving the structure of chemical plumes and locating the odor source. The antennule is also adapted to maintain lifelong function in a changing environment. For example, it has specific secretory glands, grooming structures, and behaviors to stay clean and functional. Antennular sensilla and the annuli on which they reside are also added and replaced, leading to a complete turnover of the antennule over several molts. Thus, the antennule is a complex and dynamic sensory-motor integrator that is intricately engaged in most aspects of the lives of crustaceans.

Incubation Temperature and Maternal Resource Provisioning, but Not Contaminant Exposure, Shape Hatchling Phenotypes in a Species with Temperature-Dependent Sex Determination.

Abstract: The environment experienced during embryonic development is a rich source of phenotypic variation, as environmental signals have the potential to both inform adaptive plastic responses and ...

Dominance Hierarchies in Marine Invertebrates

Abstract: Dominance hierarchies have been well studied in myriad terrestrial animals, but surprisingly little is known about hierarchies in marine invertebrates; examples are limited to a few species...

Possible Roles of Hypotaurine and Thiotaurine in the Vesicomyid Clam Phreagena okutanii.

Abstract: Vesicomyid clams, which inhabit deep-sea hydrothermal vents and hydrocarbon seeps, are nutritionally dependent on symbiotic, chemoautotrophic bacteria that produce organic matter by using hydrogen sulfide. Vesicomyid clams absorb hydrogen sulfide from the foot and transport it in their hemolymph to symbionts in the gill. However, mechanisms to cope with hydrogen sulfide toxicity are not fully understood. Previous studies on vent-specific invertebrates, including bathymodiolin mussels, suggest that hypotaurine, a precursor of taurine, mitigates hydrogen sulfide toxicity by binding it to bisulfide ion, so as to synthesize thiotaurine. In this study, we cloned cDNAs from the vesicomyid clam Phreagena okutanii for the taurine transporter that transports hypotaurine into cells and for cysteine dioxygenase and cysteine-sulfinate decarboxylase, major enzymes involved in hypotaurine synthesis. Results of reverse-transcription polymerase chain reaction indicate that mRNAs of these three genes are most abundant in the foot, followed by the gill. However, hypotaurine and thiotaurine levels, measured by reverse-phase high-performance liquid chromatography, were low in the foot and high in the gill. In addition, thiotaurine was detected in hemolymph cells. Hypotaurine synthesized in the foot may be transported to the gill after binding to bisulfide ion, possibly by hemolymph cells.

Behavioral Variability of Hatchlings Modifies Dispersal Potential in Crown Conch (Melongena corona): Why Do Larvae Crawl Away but Sometimes Swim?

Abstract: The diversity and consequences of development in marine invertebrates have, for a long time, provided the opportunity to understand different evolutionary solutions to living in variable en...

Rare-Earth Magnets Influence Movement Patterns of the Magnetically Sensitive Nudibranch Tritonia exsulans in Its Natural Habitat.

Abstract: The nudibranch Tritonia exsulans (previously Tritonia diomedea) is known to have behaviors and neurons that can be modified by perturbations of the Earth's magnetic field. There is no definitive evidence for how this magnetic sense is used in nature. Using an exploratory approach, we tested for possible effects of magnetic perturbations based on underwater video of crawling patterns in the slugs' natural habitat, with magnets of varying strength deployed on the substrate. For analysis, we used a paired comparison of tracks of animals between segments 25-50 cm distant from the magnets and segments of the same tracks 0-25 cm from the magnets, to determine whether any differences depended on the strength of the magnet. Most track measurements (length, displacement, velocity, and tortuosity) showed no such differences. However, effects were observed for the changes in track headings between successive points. These results showed that tracks had relatively higher heading variability when they moved closer to stronger magnets. We suggest that this supports a hypothesis that T. exsulans continuously uses a magnetic sense to help maintain straight-line navigation. Further specific testing of the hypothesis is now needed to verify this new possibility for how animals can benefit from a compass sense.

Influence of Maternal Size on Offspring Traits in a Marine Gastropod with Direct Development and without Sibling Interaction.

Abstract: In most animal taxa, large mothers (or those with high nutritional status) produce large offspring, leading to a maternal size-offspring size correlation, that is, a positive correlation be...

Differential Tolerance and Seasonal Adaptation to Temperature and Salinity Stress at a Dynamic Range Boundary Between Estuarine Gastropods.

Abstract: Insight into how coastal organisms will respond to changing temperature and salinity regimes may be derived from studies of adaptation to fluctuating estuarine environments, especially unde...

Larvae of Deep-Sea Invertebrates Harbor Low-Diversity Bacterial Communities.

Abstract: Microbial symbionts are a common life-history character of marine invertebrates and their developmental stages. Communities of bacteria that associate with the eggs, embryos, and larvae of ...