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Naticid gastropods provide a highly tractable system for exploring ontogenetic changes in diet because the telltale boreholes they leave behind in their hard-shell molluscan prey can be linked reliably to naticid size. In this study, ontogenetic changes in diet and size selectivity across 7 common prey species of Lunatia heros (Say, 1822) were explored using a forensic approach based on beach-collected shells from the eastern coast of Nova Scotia, Canada. Laboratory experiments were also undertaken to assess the relationship between predator size and outer borehole diameter (OBD) for 3 of these prey species. The results confirmed a strong relationship between OBD and shell length for L. heros and demonstrated that this relationship was consistent across prey species varying in shell thickness and composition. Analyses of drilled, beach-collected shells revealed that L. heros clearly differentiates among prey with respect to size and species, with ontogenetic changes in prey selection appearing to...

Although considered major players in many ecosystems around the world, the ecology of Caspian Sea polychaetes is currently understudied. This study describes the species composition and quantitative distribution of polychaetes in the southern Caspian Sea and relates the distribution to seasonal changes in environmental parameters of water (temperature, salinity, and surface current speed) and sediments (organic matter and grain size composition) at four depths (2, 5, 9 and 14 m) on the Noshahr coast in the southern Caspian Sea in 2010. Four species were found: Alitta succinea , Hediste diversicolor , Hypania invalida , and Streblospio gynobranchiata . Among them, the non-indigenous S. gynobranchiata was the dominant species, accounting for 87% of the total abundance. Significant differences in abundance across the four species were observed among depths and seasons. Additionally, significant correlations between species abundances and the tested environmental factors were evident. This study highlights the potential consequences of established non-indigenous species in the southern Caspian Sea.

Although ocean acidification is expected to reduce carbonate saturation and yield negative impacts on open-ocean calcifying organisms in the near future, acidification in coastal ecosystems may already be affecting these organisms. Few studies have addressed the effects of sedimentary saturation state on benthic invertebrates. Here, we investigate whether sedimentary aragonite saturation (Ωaragonite) and proton concentration ([H+]) affect burrowing and dispersal rates of juvenile soft-shell clams (Mya arenaria) in a laboratory flume experiment. Two size classes of juvenile clams (0.5–1.5 mm and 1.51–2.5 mm) were subjected to a range of sediment Ωaragonite and [H+] conditions within the range of typical estuarine sediments (Ωaragonite 0.21–1.87; pH 6.8–7.8; [H+] 1.58 × 10− 8–1.51 × 10- 7) by the addition of varying amounts of CO2, while overlying water pH was kept constant ~ 7.8 (Ωaragonite ~ 1.97). There was a significant positive relationship between the percent of juvenile clams burrowed in still water and Ωaragonite and a significant negative relationship between burrowing and [H+]. Clams were subsequently exposed to one of two different flow conditions (flume; 11 cm s− 1 and 23 cm s− 1) and there was a significant negative relationship between Ωaragonite and dispersal, regardless of clam size class and flow speed. No apparent relationship was evident between dispersal and [H+]. The results of this study suggest that sediment acidification may play an important role in soft-shell clam recruitment and dispersal. When assessing the impacts of open-ocean and coastal acidification on infaunal organisms, future studies should address the effects of sediment acidification to adequately understand how calcifying organisms may be affected by shifting pH conditions.

Biological interactions between predators and prey constitute a key component of the ecology and evolution of marine systems, and animal behavior can affect the outcome of predator–prey interactions. It has been recently demonstrated that CO2-induced ocean acidification can alter the behavior of marine organisms and potentially alter predator–prey dynamics. This study combines both quantitative (meta-analysis) and qualitative approaches to review the effects of ocean acidification on behavioral prey defenses in marine invertebrates. A systematic literature search identified 34 studies that experimentally assessed behavioral defenses under elevated pCO2 spanning three phyla: crustaceans, echinoderms, and molluscs. A meta-analysis suggested that exposure to elevated seawater pCO2 can negatively affect behavioral defenses in bivalve molluscs and malacostracan crustaceans. By contrast, defenses of cephalopod molluscs seem to be positively impacted by elevated pCO2, whereas gastropods and echinoids appear unaffected. A qualitative assessment of studies on combined effects of ocean acidification and warming revealed that combined effects typically differ from ocean acidification–only effects. Based on a qualitative assessment of three studies to date, neurological interference of GABAA receptors under elevated pCO2 may play a major role in ocean acidification effects on prey defense behaviors; however, more research is needed, and other mechanistic underpinnings are also important to consider. Ultimately, the results of this study suggest that behavioral prey defenses in some shellfish taxa may be vulnerable to ocean acidification, that the effects of ocean acidification are often different under warming scenarios than under present-day temperature scenarios, and that GABAA interference may be an important mechanism underpinning behavioral responses of shellfish prey under ocean acidification. Despite the importance of shellfish behavioral defenses in the ecology and evolution of marine biological communities, however, research to date has only scraped the surface in understanding ocean acidification effects. Increased research efforts on the effects of multiple stressors, acclimation and adaptation, environmental variability, and complex situational and ecological contexts are needed. Studies of fish behavioral defenses under ocean acidification can help streamline hypotheses and experimental approaches, particularly given the similar effects of elevated pCO2 on GABAA function.

Although ocean acidification studies related to marine animal behavior have increased in recent years, the behavioral effects of ocean acidification on shellfish are relatively understudied, even though marine shellfish exhibit a wealth of behaviors that can modify organismal interactions and biological community functioning. Furthermore, detecting acute behavioral changes may provide a biological indicator of ecosystem stress and/or an early warning system for aquaculture operations. This article highlights a new and emerging technology—high-frequency noninvasive (HFNI) electromagnetic biosensors—that can be used to document acute and long-term effects of elevated CO2 on the valve-gaping behavior of marine bivalves. An overview of the technology is presented, and the current and potential uses of these biosensors in ocean acidification research are highlighted, along with current limitations and next steps. Although a handful of studies have used these biosensors to test for effects of acidification on bivalve valve-gaping behavior, their potential for testing critical and novel hypotheses regarding ocean acidification effects in a broader range of shellfish taxa is currently underused. Ultimately, this article provides a basis for expanding ocean acidification research on shellfish behavior through the use of HFNI electromagnetic biosensors.

Lunatia heros (Say, 1822) is a common predatory gastropod in soft-sediment marine environments along the northwestern Atlantic coast. While recognized as a major predator of several commercially important molluscs, little is known about the diet breadth of L. heros and the potential of this species to exploit a broader range of molluscan taxa. Here, using a forensic approach based on beach-collected shells, we document prey species drilled by L. heros in eastern Cape Breton, Nova Scotia, Canada, and compare our findings to those reported in the literature for this species. Our results indicate that L. heros consumes a wider range of prey species than the fifteen currently reflected in the literature. In beach surveys, representatives of twenty of the twenty-eight molluscan species collected were found with beveled boreholes, nine of which were previously unreported as prey items of L. heros. Our findings thus confirm the generalist feeding tendencies of this species and increase the number of re...

Sediment acidification is known to influence the burrowing behaviour of juvenile marine bivalves. Unlike the alteration of behaviour by ocean acidification (OA) observed in many marine organisms, this burrowing response to present-day variation in sediment pH is likely adaptive in that it allows these organisms to avoid shell dissolution and mortality. However, the consequences of global climate stressors on these burrowing responses have yet to be tested. Further, while neurotransmitter interference appears to be linked to the alteration of behaviour by OA in marine vertebrates, the mechanism(s) controlling the burrowing responses of juvenile bivalves in response to present-day variation in sediment acidification remain unknown. We tested the interactive effects of elevated seawater temperature and sediment acidification on juvenile soft-shell clam burrowing behaviour (measured as the proportion of clams burrowed into sediment) to test for effects of elevated temperature on bivalve burrowing responses to sediment acidification. We also examined whether GABAA-like receptor interference could act as a potential biological mechanism underpinning the burrowing responses of these clams to present-day variation in sediment acidification. Results showed that both elevated temperature and gabazine administration reduced the proportion of clams that avoided burrowing into low pH sediment. These results suggest that CO2 effects on neurophysiology (GABAA receptors) can act to mediate adaptive behaviours in juvenile marine bivalves to elevated CO2, but that these behaviours may be adversely affected by elevated temperature.

Ocean acidification poses a threat to marine organisms. While the physiological and behavioural effects of ocean acidification have received much attention, the effects of acidification on the susceptibility of farmed shellfish to parasitic infections are poorly understood. Here we describe the effects of moderate (pH 7.5) and extreme (pH 7.0) ocean acidification on the susceptibility of Crassostrea virginica shells to infection by a parasitic polydorid, Polydora websteri. Under laboratory conditions, shells were exposed to three pH treatments (7.0, 7.5 and 8.0) for 3- and 5-week periods. Treated shells were subsequently transferred to an oyster aquaculture site (which had recently reported an outbreak of P. websteri) for 50 days to test for effects of pH and exposure time on P. websteri recruitment to oyster shells. Results indicated that pH and exposure time did not affect the length, width or weight of the shells. Interestingly, P. websteri counts were significantly lower under extreme (pH 7.0; ~50% reduction), but not moderate (pH 7.5; ~20% reduction) acidification levels; exposure time had no effect. This study suggests that extreme levels – but not current and projected near-future levels – of acidification (∆pH ~1 unit) can reduce the susceptibility of eastern oyster shells to P. websteri infections.

While ocean acidification is considered among the greatest threats to marine ecosystems, its effects on the feeding performance of marine calcifiers remain uncertain. I conducted a meta-analysis of effect sizes (LnRR) assessing the impacts of acidification on the feeding ability of three groups of marine calcifiers - molluscs, arthropods, and echinoderms. Results suggested taxon-dependent effects of acidification on calcifier feeding performance, with depressed feeding observed for molluscs, echinoderms, and when all taxa were considered. However, ocean acidification had no effect on feeding performance in marine arthropods and larval feeding performance appeared more vulnerable than that of juveniles and adults. Feeding performance was not related to acclimation time nor pCO2 level. This study suggests that the feeding performance of molluscs and early life-stage echinoderms may be depressed in a more acidic ocean, but that arthropod feeding performance is unlikely to suffer. Such changes in feeding performance could contribute to slower growth and development in the early life stages of these organisms and could potentially contribute to changes in community and ecosystem structure where these organisms coexist. Finally, feeding performance could, at least in part, moderate the degree to which molluscs and echinoderms can use food to overcome acidification effects early in life.

While ocean acidification (OA) effects on marine organisms are well documented, impacts of sediment acidification on infaunal organisms are relatively understudied. Here we synthesize CO

A case study was conducted to assess the efficacy of online communication tools for enhancing independent student engagement in a first-year undergraduate class. Material relevant to course topics was shared with students through three communication platforms and data were extracted to measure student engagement. A questionnaire was also used to validate online data and determine why students chose a particular platform. Online results revealed that more than half of the students engaged with at least one post to some degree through one or more communication platforms. Facebook was the primary platform for student engagement. Students primarily engaged with material on Facebook by “liking” posts and used Facebook to share relevant material that they came across personally. There was no significant difference in student engagement with shared material between instructor-shared and student-shared posts, although Facebook engagement was 29% higher when the instructor commented and/or liked a post 1 day after sharing. Questionnaire results suggested that 90% of all students engaged with material to some extent. Most students engaged with between 3 and 10 posts by seeing a post, clicking the associated link, and reading the material. The majority of students engaged through Facebook and felt most comfortable with this platform. Of those engaging at the highest level, 66% used Facebook. Convenience appeared to be the dominant reason for engaged students choosing a particular platform. Weakly positive relationships between academic performance vs. overall engagement and engagement level were apparent. This study suggests that Facebook can be used to enhance independent student engagement.