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Generalized Additive Mixed-effect Model and LMM results for righting time (min) over 68 days of incubation.
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During recent years, experimental ecology started to focus on regional to local environmental fluctuations in the context of global climate change. Among these, marine heatwaves can pose significant threats to marine organisms. Yet, experimental studies that include fluctuating thermal stress are rare, and if available often fail to base experiment...
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Starfish are keystone species as predators in benthic ecosystems, but when population outbreaks occur this can have devastating consequences ecologically. Furthermore, starfish outbreaks and invasions can have adverse impact economically by impacting shellfish aquaculture. Addressing the imperative need to proactively mitigate starfish invasions re...
Citations
... More and more, the vulnerability of key marine species to MHWs becomes apparent. Prominent examples are the starfish Asteria rubens (Rühmkorff et al., 2023) and the seagrass Zostera marina (Wolf et al., 2022). The first is considered a key predator in the Baltic Sea while the seagrass transfers huge amounts of carbon and nutrients to the sediments, and thus, provides an important ecosystem service to mitigate the effect of anthropogenic carbon emissions and eutrophication (Röhr et al., 2018). ...
... Sea stars often play important ecological roles as predators and grazers in benthic and intertidal communities [15][16][17]. As such, there has been an increasing desire to better understand their general ecology [18] and to examine how this may change in the context of global change [19,20]. Sea star movement ecology has been previously studied using plastic or similar tags to follow animals in situ [21][22][23], repeated diver observations [24,25], and laboratory observations [26]. ...
Background
Acoustic telemetry is an important tool to study the movement of aquatic animals. However, studies have focussed on particular groups of easily tagged species. The development of effective tagging methods for ecologically important benthic species, such as sea stars, remains a challenge due to autotomy and their remarkable capacity to expel any foreign material. We tested three methods to surgically attach acoustic transmitters to the common sea star Asterias rubens; two methods attached the tag to the aboral side of the central body and the third attached the transmitter to the aboral side of an arm. Laboratory experiments evaluated each method in terms of survivability, tag retention, associated injuries, and changes in feeding behaviour and physical condition.
Results
Laboratory results were highly variable; however, all tagging methods caused significant injury to the epidermis and deeper tissue around the attachment site over periods greater than 4 weeks. Attaching a tag by horizontally piercing the central body (method HPC) had minimal effects in the short-term (2–3 weeks) and this method was used for a pilot tagging study in the field, where 10 sea stars were tagged and placed within an existing acoustic telemetry array. Although, the interpretation of field data was challenging due to the characteristic slow movement of sea stars, movements of a similar magnitude to previous studies were identified during the 2–4 weeks after sea stars were tagged and released. However, this apparent period of tagging success was followed by a reduction in movement that, when viewed in conjunction with laboratory results, potentially indicated a deterioration in the sea stars’ physical condition.
Conclusions
While acoustic telemetry continues to provide novel insights into the ecology of a wide variety of marine species, species-specific effects of tagging should be evaluated before starting field studies. If the autonomous study of benthic movement is to expand beyond hard-bodied macroinvertebrates current methodological and analytical challenges must be addressed.
... Disturbances of this predator-prey interaction caused by climate change and extreme events [21] can affect mussel bed formation and the functioning of associated ecosystems [22]. A. rubens inhabits the inter-and subtidal zones of the North Atlantic region [23][24][25]. Across its distribution range, A. rubens experiences marine heatwaves and upwelling conditions, e.g. in Chesapeake Bay, St Lawrence Bay, Long Island Sound [26,27] or in the North and Baltic Seas [28,29]. Electronic supplementary material S1 contains further details on the distribution and on temperature, salinity, acidification and oxygen tolerance of A. rubens. ...
... Interestingly, recovery from these heatwaves was possible and compensatory feeding could alleviate the overall negative impact on growth. Recovery of marine species following heatwaves was also shown in previous studies [29,49] and therefore might represent a crucial aspect in species (and ecosystem) responses to climate change [49]. Although starfish tended to increase their feeding rate after an extended heatwave of the same peak temperature, they could not recover fully. ...
Climate change increases the frequency and intensifies the magnitude and duration of extreme events in the sea, particularly so in coastal habitats. However, the interplay of multiple extremes and the consequences for species and ecosystems remain unknown. We experimentally tested the impacts of summer heatwaves of differing intensities and durations, and a subsequent upwelling event on a temperate keystone predator, the starfish Asterias rubens. We recorded mussel consumption throughout the experiment and assessed activity and growth at strategically chosen time points. The upwelling event overall impaired starfish feeding and activity, likely driven by the acidification and low oxygen concentrations in the upwelled seawater. Prior exposure to a present-day heatwave (+5°C above climatology) alleviated upwelling-induced stress, indicating cross-stress tolerance. Heatwaves of present-day intensity decreased starfish feeding and growth. While the imposed heatwaves of limited duration (9 days) caused slight impacts but allowed for recovery, the prolonged (13 days) heatwave impaired overall growth. Projected future heatwaves (+8°C above climatology) caused 100% mortality of starfish. Our findings indicate a positive ecological memory imposed by successive stress events. Yet, starfish populations may still suffer extensive mortality during intensified end-of-century heatwave conditions.
... Because our short-term oxygen records show that compound extreme events occur during MHWs, and because long-term temperature records show that there is a 50% chance of reefs experiencing at least one MHW per year, the frequency of such compound events is likely to be either underestimated and/or increasing. This agrees well with the small but growing body of research that unanimously emphasizes the severe biological and ecological impacts of compound extreme ocean events (Ummenhofer et al., 2017;Gruber et al., 2021;Wolf et al., 2022). Increasing efforts to collect high-resolution oxygen and temperature data are necessary, as is knowledge of how multiple extreme stressors interact, how long extreme events last, and how their magnitude, intensity, and recurrences impact marine life. ...
The frequency, magnitude, and duration of marine heatwaves and deoxygenation events are increasing globally. Recent research suggests that their co-occurrence is more common than previously thought and that their combination can have rapid, dire biological impacts. We used the sea urchin Echinometra lucunter to determine whether mortality occurs faster when deoxygenation events are combined with extreme heating (compound events), compared to deoxygenation events alone. We also tested whether prior exposure to local heatwave conditions accentuates the impacts of compound events. Animals were first exposed for five days to either ambient temperature (28 °C) or a warmer temperature that met the minimum criteria for a local heatwave (30.5 °C). Animals were then exposed to hypoxia, defined as oxygen levels 35% below their average critical oxygen limit, combined with ambient or extreme field temperatures (28 °C, 32 °C). Subsets of animals were removed from the hypoxic treatments every 3 hours for 24 hours to determine how long they could survive. Prior exposure to heatwave conditions did not help or hinder survival under hypoxic conditions, and animals exposed to hypoxia under ambient temperatures experienced little mortality. However, when hypoxia was coupled with extreme temperatures (32 °C), 55% of the animals died within 24 hours. On the reefs at our Panama study site, we found that extreme hypoxic conditions only ever occurred during marine heatwave events, with four compound events occurring in 2018. These results show that short durations (∼1 day) of compound events can be catastrophic and that increases in their duration will severely threaten sea urchin populations.
... Extracting information from local environmental time series for characterizing means and variability components allows for setting appropriate experimental treatments Cabrerizo et al. 2021;Dobry et al. 2021;Kroeker et al. 2021;Wolf et al. 2022). For multiple-driver experiments, characterizing the main drivers in a system and how they covary (e.g., Wahl et al. 2021) is vital for designing ecologically relevant manipulative experiments with a feasible number of treatments (i.e., reducing the complexity of the setting by selecting the combination of factors that show high variation or covariation in nature and combine them with future scenarios). ...
The relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variability‐focused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations.
... While heatwaves are forecast to become hotter, more frequent, and longer-lasting in global coastal areas, understanding responses, acclimation and adaptation potential of intertidal bivalves to atmospheric heatwaves is still an area of uncertainty. This can be most likely attributed to the fact that simulated experiments that realistically factored in the ephemeral, drastic, and recurrent nature of heatwaves are extremely limited (e.g., Amorim et al., 2020;Scanes et al., 2020;Vázquez et al., 2021;Wolf et al., 2022;Xu et al., 2021), and also our current knowledge about responses of intertidal bivalves to marine high-temperature extremes stem largely from mesocosm arrays and natural observations (e.g., Olabarria et al., 2016;Oliver et al., 2018;Schlegel et al., 2017). Therefore, it is becoming imperative to gain an integrated understanding of how they may respond, acclimate, and adapt under more environmentally realistic heatwaves scenarios. ...
Heatwaves have become more frequent and intense in the last two decades, resulting in detrimental effects on marine bivalves and ecosystems they sustain. Intertidal clams inhabit the most physiologically challenging habitats in coastal areas and live already near their thermal tolerance limits. However, whether and to what extent atmospheric heatwaves affect intertidal bivalves remain poorly understood. Here, we investigated physiological responses of the Manila clam, Ruditapes philippinarum, to heatwaves at air temperature regimes of 40 °C and 50 °C occurring frequently and occasionally at the present day in the Beibu Gulf, South China Sea. With the increasing intensity of heatwaves and following only two days of aerial exposure, Manila clams suffered 100 % mortality at 50 °C, indicating that they succumb to near future heatwaves, although they survived under various scenarios of moderate heatwaves. The latter is couched in energetic terms across levels of biological organization. Specifically, Manila clams acutely exposed to heatwaves enhanced their standard metabolic rate to fuel essential physiological maintenance, such as increasing activities of SOD, CAT, MDA, and AKP, and expression of HSP70. These strategies occur likely at the expense of fitness-related functions, as best exemplified by significant depressions in activities of enzymes (NKA, CMA, and T-ATP) and expression levels of genes (PT, KHK, CA, CAS, TYR, TNF-BP, and OSER). When heatwaves occurred again, Manila clams can respond and acclimate to thermal stress by implementing a suite of more ATP-efficient and less energy-costly compensatory mechanisms at various levels of biological organization. It is consequently becoming imperative to uncover underlying mechanisms responsible for such positive response and rapid acclimation to recurrent heatwaves.
Predation is a dominant structuring force in ecological communities. In aquatic environments, predation on bivalves has long been an important focal interaction for ecological study because bivalves have central roles as ecosystem engineers, basal components of food webs, and commercial commodities. Studies of bivalves are common, not only because of bivalves' central roles, but also due to the relative ease of studying predatory effects on this taxonomic group. To understand patterns in the interactions of bivalves and their predators we synthesised data from 52 years of peer-reviewed studies on bivalve predation. Using a systematic search, we compiled 1334 studies from 75 countries, comprising 61 bivalve families (N = 2259), dominated by Mytilidae (29% of bivalves), Veneridae (14%), Ostreidae (8%), Unionidae (7%), and Dreissenidae and Tellinidae (6% each). A total of 2036 predators were studied, with crustaceans the most studied predator group (34% of predators), followed by fishes (24%), molluscs (17%), echinoderms (10%) and birds (6%). The majority of studies (86%) were conducted in marine systems, in part driven by the high commercial value of marine bivalves. Studies in freshwater ecosystems were dominated by non-native bivalves and non-native predator species, which probably reflects the important role of biological invasions affecting freshwater biodiversity. In fact, while 81% of the studied marine bivalve species were native, only 50% of the freshwater species were native to the system.
In terms of approach, most studies used predation trials, visual analysis of digested contents and exclusion experiments to assess the effects of predation. These studies reflect that many factors influence bivalve predation depending on the species studied, including (i) species traits (e.g. behaviour, morphology, defence mechanisms), (ii) other biotic interactions (e.g. presence of competitors, parasites or diseases), and (iii) environmental context (e.g. temperature, current velocity, beach exposure, habitat complexity). There is a lack of research on the effects of bivalve predation at the population and community and ecosystem levels (only 7% and 0.5% of studies respectively examined impacts at these levels). At the population level, the available studies demonstrate that predation can decrease bivalve density through consumption or the reduction of recruitment. At the community and ecosystem level, predation can trigger effects that cascade through trophic levels or effects that alter the ecological functions bivalves perform. Given the conservation and commercial importance of many bivalve species, studies of predation should be pursued in the context of global change, particularly climate change, acidification and biological invasions.
Salinity is a common stressor restricting the distribution of various decapod crustaceans. The interactive effects of such regional stressors with global climate change drivers are important to be considered when aiming to realistically predict the potential of a species’ dispersal and further spread into new habitats. Within species, their larval stages commonly determine a species tolerance and with this their potential to invade and successfully develop a sustaining population. This laboratory study investigated the combined effect of salinity (6 levels, 10–25) and temperature (19 and 23 °C) on larval survival, development to megalopa, and feeding (in Zoea I, III, and V) of the decapod Hemigrapsus takanoi. Larval development and survival to megalopa were generally favored by increasing salinity. While no larva developed to the megalopa stage at 23 °C and a salinity of 16, in 19 °C some larvae could successfully develop under a salinity as low as 16. All larval stages fed generally more with increasing salinity and temperature, but there was no interaction between the two factors. The results revealed that the H. takanoi population from Kiel Fjord (southwestern Baltic Sea) is capable of completing its larval development under the current Kiel Fjord environmental conditions. The geographical spread of this H. takanoi population into the wider Baltic Proper may, however, be restricted mainly due to the inability to establish and maintain a self-sustaining population under lower salinity conditions. Furthermore, the projected desalination of the Baltic Sea together with rising temperatures due to global warming and heat waves in summer may likely exert additional stress to this existing population, unless H. takanoi adapts at appropriate rates.
