Coral reefs are ecosystems that provide essential services, including coastal protection, fisheries, and biotechnological resources. Nearshore coral species are often exposed to environmental stressors such as aerial exposure during low tides, leading to functional hypoxia. While many invertebrates under aerial exposure have been extensively studied for their redox responses, cnidarians remain poorly understood in this context. This study investigates the metabolic and redox responses of the coral Pavona cactus during short-term aerial exposure (30 min) and subsequent re-immersion (+30 min). We observed a significant 4.2-fold reduction in metabolic rate during aerial exposure, followed by a 3.4-fold recovery upon re-immersion, indicating a state of functional hypoxia and reoxygenation. Catalase activity increased by 18% during aerial exposure and remained elevated during re-immersion, suggesting the preparation for oxidative stress (POS) strategy. Lipid peroxidation levels (TBARS) increased by 37% during aerial exposure but normalized upon re-immersion, while DNA damage was significantly elevated during re-immersion, indicating oxidative stress during the reoxygenation phase. Protein oxidation remained unchanged throughout the experiment. These findings demonstrate that P. cactus responds rapidly to aerial exposure with increased antioxidant capacity, exhibiting metabolic suppression and oxidative stress despite the brief emersion. The pronounced shifts in oxygen consumption and oxidative damage highlight its sensitivity to environmental fluctuations, and the activation of the POS strategy demonstrates how rapidly this species responds to acute stress conditions.
Anthropogenic underwater noise is now considered one of the ‘emerging threats and ongoing challenges to biodiversity conservation’. Physiological changes have been observed in sessile invertebrates such as bivalves. Bivalve mollusks are of particular interest because of their sensitivity to sound, their inability to move away from the sound source, and their considerable economic and social importance. A growing number of studies have examined the acoustic effects of shipping on invertebrates, but few have considered the interaction of multiple stressors to approximate a real ecological context. Noise can interact with chemical contaminants to disrupt the behavior of organisms and have complex effects. Recent studies on invertebrates have shown that noise amplifies the harmful effects of heavy metals such as cadmium. In a harbor environment in the Gulf of St. Lawrence, the stress response of post-larval mussels, Mytilus edulis, was studied using an ecophysiological-ecotoxicological approach. To achieve this, competent pediveliger larvae, previously exposed to a cocktail of pollutants simulating the maritime environment of a port until the end of embryogenesis, were exposed to acoustic perturbations during metamorphosis. The aim was to assess the response of competent larvae (i.e. during metamorphosis) following early life chemical contamination and interaction with noise exposure representative of maritime traffic. This study shows that the effects of early chemical pollution during embryogenesis have a greater impact on larvae than noise exposure later during metamorphosis. In fact, latent effects of early chemical exposure persist, with consequences for size at metamorphosis, energy and oxidative metabolism, and lipid profile of post-larvae.
The essential fatty acids (EFA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are required for the maintenance of good health in humans. In the marine environment, they are primarily synthesized by phytoplankton and their production is predicted to decrease with warming seawater temperatures. With reduced production, it becomes critical to understand the efficiency with which these EFA are transferred through trophic systems. To do this, captive Atlantic pollock (Pollachius virens) were fed one of two test diets for 83 days; both contained 11% total lipids, with one having half the absolute concentration of both EPA and DHA. Fish were hand-fed to satiation so a mass balance approach, monitoring intake and accumulation of EFA and energy, could be used to determine the FA-specific net growth efficiency (NGE). At the conclusion of the feeding study, NGE for EPA and DHA were determined at 56 and 52%, respectively, in fish fed diets that were rich in these EFA. However, in fish that received reduced dietary proportions of EPA and DHA, lower NGE, at 36 and 25%, respectively, were found, indicating that a limited ability to retain essential nutrients may exist when dietary supply is reduced. NGE for EFA in both diets, relative to energy, were 1.4–2 fold higher, offering a starting point for the development of trophic models evaluating transfer of these essential nutrients, rather than energy.
The relative importance of nitrogen source and niche differentiation in shaping Symbiodiniaceae phycosphere bacterial communities remains unclear. We compared free-living (FL) and particle-attached (PA) bacterial communities associated with the free-living Symbiodiniaceae Symbiodinium pilosum under nitrate and urea treatments using 16S rRNA gene sequencing. The results showed that bacterial lifestyle, rather than nitrogen source, was the primary driver of community assembly. PCoA and PERMANOVA analyses revealed a clear structural separation between FL and PA communities, whereas nitrogen source had no significant effect on overall community structure. Alpha diversity analysis further indicated niche-specific responses: under nitrate treatment, the PA community exhibited significantly higher Shannon diversity, while the FL community showed higher richness. At the phylum level, Pseudomonadota and Bacteroidota dominated across all samples, accounting for more than 90% of total sequences. At the genus level, Amorphus dominated the FL community, whereas the oligotrophic KI89A clade was enriched in the PA fraction. Core microbiome analysis showed that KI89A clade, Amorphus, and Muricauda were the core genera shared across all four treatment groups. Compared with the structurally simplified and specialized PA core, the FL community possessed a more complex core microbiome. These findings highlight strong niche differentiation and reveal a conserved core microbiome composed of Amorphus, KI89A clade, and Muricauda in the phycosphere of S. pilosum, providing insights into niche differentiation and conserved core microbiome structure in Symbiodiniaceae-associated bacterial communities.
Feeding conditions can significantly influence physiological responses in marine copepods in experimental trials. For benthic harpacticoids, diatoms represent the dominant and ecologically relevant food source. However, maintaining live diatom cultures is labour-intensive and introduces variability across replicates and time, potentially compromising experimental consistency and reproducibility. This study evaluates whether freeze-dried diatom cells can serve as a standardised dietary substitute without altering the fatty acid composition of benthic harpacticoid copepods. Using Platychelipus littoralis as a model species, we show that copepods fed with either fresh or freeze-dried Nitzschia sp. cells showed similar fatty acid profiles. The relative proportions of essential fatty acids, including eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), remained consistent between these two feeding conditions. This suggests that the lyophilisation process preserves the nutritional quality of the diatom cells, specifically in terms of fatty acid concentration and composition. These findings confirm that freeze-dried diatom cells are a suitable alternative to fresh food during laboratory experiments with benthic harpacticoid copepods, offering standardised and low-maintenance feeding conditions. The use of freeze-dried diatoms enhances experimental reproducibility and reduces the logistical burden of using live algal cultures in benthic copepod research.
The mechanisms linking dietary inputs to assimilation and growth are difficult to disentangle in natural systems. In marine environments, wood-boring bivalves exploit a carbon-rich but nitrogen-poor resource, raising questions about how substrate type constrains nutrient assimilation and performance. We conducted controlled immersions of alder, beech, and spruce logs and measured δ13C and δ15N values and body size in Bankia carinata. Consumer δ13C values mirrored those of wood, spanning a 5‰ range from alder to spruce, indicating direct assimilation of wood-derived carbon. In contrast, δ15N values were consistently enriched relative to wood, increasing from +3.2‰ on alder to +5.7‰ on spruce, pointing to a shift in nitrogen isotopic fractionation with increasing substrate nitrogen scarcity. Maximum body size was strongly reduced on nitrogen-poor spruce (C:N = 545), with maximum observed sizes of 3 cm versus 7 cm on beech (C:N = 282) and 15 cm on alder (C:N = 182). These results show that the wood substrates examined generated contrasting patterns of resource assimilation and consumer growth performance under controlled conditions.
Tegula funebralis is a gregarious trochoid gastropod from the Pacific coast of North America that influences intertidal ecosystems by suppressing local kelp populations and serving as a dietary staple for predators such as sea-stars and crabs. Tegula funebralis inhabits a wide range of rocky intertidal habitats with diverse energetic and predation pressures. Many intertidal gastropods respond to changes in environmental energy and predation pressure by plastically altering the size of their foot and shape of their aperture; however, no previous research has examined whether T. funebralis exhibits the same morphological variability. In this study, we use two-dimensional geometric morphometrics to determine whether T. funebralis aperture shape varies among 90 specimens sourced from three distinct populations situated along a well-documented energy and predation gradient near Bamfield, British Columbia, Canada. We performed a generalized Procrustes analysis on one anatomical landmark and 89 sliding semi-landmarks situated along the perimeter of the aperture. A principal component analysis identified a significant separation in aperture shapes among the three populations. Thin-plate spline deformations demonstrated that specimens from the high-energy, low-predation population have proportionally shorter and wider apertures than specimens from the low-energy, high-predation population. Short and wide apertures may facilitate a larger, more powerful foot to help the gastropods maintain purchase in high-energy settings; meanwhile, long and narrow apertures may impede shell-entry attacks in high-predation settings. Additionally, spire heights are significantly shorter in populations experiencing high predation, suggesting larger specimens may be less common due to slower growth rates, phenotypic plasticity, or differential predation.
The green crab (Carcinus maenas) is an extremely successful invasive species, known for its tolerance to environmental perturbations. While the thermal limits and hypoxia tolerance of green crabs have been well studied, the potential benefit of an oxygen surplus during acute thermal stress remains unclear. We use a multi-stressor approach to evaluate the oxygen dependence of upper thermal limits in green crabs captured from the Swedish North Sea and the Canadian Pacific. We use measurements of oxygen consumption (ṀO2) to investigate how environmental dissolved oxygen (50%, 100% and 150% air saturation) influences upper thermal limits of green crabs from capture sites on two continents. Under normoxia, green crabs exhibited an increase in ṀO2 from the 16 °C acclimation temperature to a peak ṀO2 at 34.8 ± 1.4 °C in Swedish crabs and 34.6 ± 0.4 °C in Canadian crabs, followed by an abrupt decline and collapse at their upper thermal limits. Corresponding heart rate (HR) measurements in Swedish green crabs mirrored the patterns observed in ṀO2. Swedish and Canadian green crabs also responded similarly to environmental oxygen, exhibiting consistent reductions in upper thermal limits (the point of metabolic collapse) in hypoxia and negligible improvement between normoxia and hyperoxia. Thus, we propose that while green crab thermal tolerance is oxygen limited in hypoxia, at normoxia and above, thermal tolerance is instead dependent on the collapse of other vital physiological functions. These results contrast previous suggestions of oxygen and capacity limited thermal tolerance in green crabs and other crustaceans in normoxia.
Estuarine ecosystems are characterized by strong temporal and spatial variability in environmental conditions, particularly temperature and salinity. These parameters often fluctuate simultaneously, potentially generating combined stress that may affect the physiological performance and survival of resident organisms. In the context of climate change, understanding how estuarine species respond to such interacting stressors has become increasingly important. This study investigates the effects of temperature and salinity, and their interaction, on the survival and metabolic response of the bloody cockle Senilia senilis, a key benthic species of the Sine Saloum estuary (Senegal). Experiments were conducted in situ using the mobile laboratory Galou Xam Xam, allowing controlled ecophysiological measurements close to natural environmental conditions. First, thermal tolerance was assessed by exposing individuals to increasing temperatures to determine the median lethal temperature (LT₅₀). Second, respiration rates were measured across a thermal gradient to evaluate metabolic sensitivity to temperature. Finally, survival was monitored under different combinations of temperature (30–39 °C) and salinity (12–62) to examine their combined effects. Results indicate that S. senilis exhibits relatively high thermal tolerance, with an LT₅₀ of 39.6 °C after 24 h. Respiration rates increased with temperature, indicating strong metabolic sensitivity (Arrhenius temperature TA = 6925 K). Survival analyses revealed significant effects of temperature, salinity, and their interaction, with marked reductions in survival under extreme thermohaline conditions. An optimal thermohaline window was identified between 30 and 35 °C and salinities of 20–40. These findings highlight the vulnerability of S. senilis to extreme environmental conditions and provide key physiological parameters for predicting the responses of estuarine populations to future climate-driven hydroclimatic changes.
Nutrient availability strongly influences the physiology and metabolic regulation of Symbiodiniaceae algae, with important implications for coral reef sulfur cycling. Dimethylsulfoniopropionate (DMSP) is a major marine sulfur compound and the primary precursor of dimethyl sulfide (DMS), a climatically active gas. In this study, we examined the effects of nitrogen and phosphorus deprivation on growth, lipid accumulation, and DMSP/DMS dynamics in cultured Symbiodiniaceae. Both nutrient limitations significantly suppressed algal growth and induced pronounced lipid droplet accumulation, indicating metabolic reprogramming under nutrient stress. While intracellular DMSP levels remained relatively stable across growth phases and nutrient conditions, DMS production showed strong temporal and nutrient-dependent variation. Nitrogen deprivation triggered a rapid increase in DMS emission, peaking on the third day of cultivation. Comparisons between free-living and symbiotic Symbiodiniaceae revealed that DMS production was absent in symbiotic cells and significantly suppressed in free-living cells exposed to coral host mucus. These results demonstrate host-mediated regulation of sulfur metabolism and highlight the sensitivity of sulfur cycling to nutrient stress in coral–algal symbioses.
Since 2008, Mediterranean small pelagic fish populations, particularly sardines Sardina pilchardus, have shown shrinking and adult overmortality, likely driven by bottom-up processes. Although energy availability has declined, adults still invest heavily in reproduction, possibly at the expense of other traits such as maintenance, growth and survival. Such trade-offs may alter their immune status, making individuals more prone to diseases. Here, we experimentally investigated the effects of seasonal feeding conditions (winter vs. summer) on sardine immune status. We provided the first description of leucocyte populations in sardines, including both non-specific and adaptive immune cells. Feeding conditions did not highly affect proportions of immune cells. However, the oxidative status of leucocytes was modified over time, likely reflecting seasonal changes, including energy re-allocation mechanisms during reproduction. These findings suggest that poor feeding conditions do not necessarily affect negatively immune status, but this requires confirmation through immune challenges.
Consumption significantly structures marine benthic communities, and understanding predator-prey interactions is crucial for determining the dynamics of these systems. Yet consumer effects in sub-Arctic regions, particularly at sites with different environmental conditions, remain underexplored. This study investigated the impact of potential predators, such as crabs and birds, on macrobenthos abundance, biomass, and biodiversity in the midintertidal of one site with low and another site with high freshwater influence in Malangenfjord, Northern Norway. Moreover, microphytobenthos biomass and delta 13C and delta 15N stable isotope values of macrobenthos and different organic matter endmembers were measured. A three-month predator-exclusion experiment, run in two consecutive years, revealed weak to moderate predator effects on macrobenthos abundance and biomass, while biodiversity remained unaffected by predator-exclusion and riverine input. Predator-exclusion effects were generally stronger at the more river-influenced site. Microphytobenthos biomass increased slightly with predator exclusion, indicating complex trophic interactions. Stable isotopes revealed limited assimilation of terrestrial organic matter by macrobenthos, suggesting that the benthos is dependent on marine-derived carbon sources. These results suggest limited predation pressure on macrobenthos and that riverine inputs potentially mitigate predator-mediated reductions in prey biomass through nutrient enrichment, as the latter leads to higher primary production and food availability. This study underscores the importance of local environmental conditions in shaping predator-prey dynamics and highlights complex interplay between riverine inputs and the ecology of coastal ecosystems. The results contribute to understanding the interactions within sub-Arctic intertidal systems and indicate the need for future research to explore mechanisms and long-term effects of riverine-coastal interactions.
While many organisms living in naturally variable environments have evolved tolerance to moderate environmental fluctuations, anthropogenic influences are driving more frequent and extreme climate events. The timing and sequence of stressor events may alter the responses of organisms. For instance, in the intertidal zone, organisms can experience daily temperature extremes that range by 10 or more degrees C. When the weather changes, a heat or cold event can further precede or follow a high rainfall, which "freshens" intertidal habitats. We selected a high intertidal copepod, Tigriopus californicus, for our experiment because it is exposed to extremes of both temperature and salinity stress, and lives at high density in intertidal pools in all seasons of the year. We designed two experiments to test whether repeated extreme heat or freshening leads to different survival outcomes compared to a heat stress that falls before or after a freshening event (double heat, double freshening, heat then freshening, freshening then heat). The second set of experiments had the same design, however, with cold stress replacing heat. To test if a "rest" period between stressors influences survivorship, we integrated different latency periods (0, 12, 24 h) across all experiments. We found that double or single (followed or preceded by an extreme temperature exposure) freshening stress led to lower survival in comparison to double temperature stress (both heat and cold). Sequence pattern further influenced the probability of survival when freshening was applied with heat, but not cold. But we found no shift in survivorship with latency periods of up to 24 h. Our results highlight the importance of considering the specific order and timing of naturally relevant stressors in experimental designs aimed at understanding how organisms respond to multiple stressors.
Ecological communities are structured by the interaction of bottom-up forces such as nutrients and temperature, which affect primary production rates, and top-down forces such as herbivory and predation, which alter the abundance and competitive dynamics of lower trophic levels. In marine ecosystems, wave exposure simultaneously influences both bottom-up processes and the ability of herbivores to forage. It is unclear how these forces balance across wave exposure gradients to regulate benthic diversity and community composition. This study examines how herbivory and wave exposure interact to structure benthic communities in the Galapagos. We re-assessed data from a field experiment manipulating urchin and fish herbivore access in a field experiment across four sites and two time periods spanning a wave exposure gradient. Wave-induced water motion was measured in-situ with an acoustic doppler velocimeter. We evaluated the effect of variable access to herbivores across wave exposures on benthic community species richness, multivariate community structure, and co-occurrence networks. Low wave energy conditions yielded overall lower community complexity, where herbivory reduced richness to only grazer-resistant species that were randomly distributed. In contrast, high wave energy supported more complex communities where herbivory increased richness and reduced determinism by limiting competitive exclusion by fast-growing species. Urchins had stronger negative effects on community structure at low-flow sites due to destructive grazing, while fishes enhanced species richness at high-flow sites by limiting species that would otherwise dominate the struggle for space. In this manner wave exposure effectively reversed the impact of top-down control on benthic community diversity, with implications for managing marine ecosystems in a period of intense environmental change.
Cytochrome P450 mono-oxygenases (CYPs) are crucial for metabolic plasticity and environmental adaptation, yet their roles in marine invertebrates from extreme habitats remain largely unexplored. The echiuran worm Urechis unicinctus, an inhabitant of sulfidic intertidal zones, exhibits remarkable tolerance to environmental stressors. Here, we present the first comprehensive characterization of its CYPs by integrating genomics, phylogenomics, and multi-condition transcript profiles. We identified 81 Urechis unicinctus Cytochrome P450 (UuCYP) genes, which represents a significant expansion compared to related annelids. Phylogenetic analysis segregated these genes into nine clades, highlighted by a striking lineage-specific expansion in Clade XI, likely driven by tandem duplication. Transcriptomic profiling revealed distinct spatio-temporal expression patterns, with specific UuCYP clusters highly expressed in detoxification-associated tissues (e.g., mid-gut, anal sacs) and during key developmental transitions. Critically, experimental sulfide exposure triggered a rapid and complex transcriptional reprogramming of the UuCYPs, partitioning genes into discrete early- and late-response modules. Co-analysis of cis-regulatory elements implicates stress-responsive pathways, for example ZSCAN16, in orchestrating this sulfide-induced response. Our findings illuminate the evolutionary dynamics and regulatory architecture of the CYP superfamily in the U. unicinctus, establishing that the diversification and transcriptional plasticity of the UuCYPs are pivotal components of its adaptation to sulfidic environments.
The European green crab (Carcinus maenas) is a highly invasive marine decapod native to Europe and Northern Africa. The minimum seasonal water temperature has been hypothesised to be a major limiting factor for green crab's range expansion. Green crabs were first found in Placentia Bay, Newfoundland, Canada (NL) in 2007; this location experiences some of the lowest winter water temperatures throughout both their native and expanded range. We carried out laboratory and field experiments to determine the behavioural responses and habitat use of green crabs to low temperatures characteristic of winters in NL. Our results showed that green crabs were absent from the intertidal zone from December to April (1-3 degrees C). Similarly, monthly catch rates declined substantially in the shallow subtidal zone during the winter months (January to March) with very low numbers or no crabs caught when water temperatures were lowest (0-3 degrees C). During long-term exposure (28 d) to 2 degrees C in a laboratory mesocosm, green crabs spent most of their time under shelter, with a concomitant reduction in locomotor and feeding activity. In situ acoustic monitoring, showed that crabs remained within a sheltered bay during the winter and did not migrate outside the bay into deeper water. In combination, the field and laboratory data showed that crabs exhibited reduced locomotor activity during the colder months. However, the fact that they did not completely cease activity but continued to move and feed at a lower rate, supports the idea that they enter a dormant state rather than a complete torpor during the cold NL winter period.
The increase in atmospheric heat retention-driven by the growing presence of greenhouse gases-has generated concern due to the potential effects on biological processes and biodiversity, especially in aquatic environments. In this study, we investigate the influence of increased temperature (24.3 degrees C), associated or not with saline stress, on biochemical and physiological parameters related to calcification and osmoregulation in two species: bivalve Amarilladesma mactroides and crab Neohelice granulata. Following acute exposure, animals were subjected to four experimental conditions: control, saline stress, heat stress and combined conditions. Hemolymph osmolality and ionic composition were analyzed, along with the activity key enzymes involved in these regulatory processes including carbonic anhydrase, Ca2+-ATPase and Na+/K+-ATPase. Our results revealed that hemolymph osmolality in the yellow clam was mainly influenced by salinity variations (28%o-* 35%o), since the species began to manifest the pattern of osmotic regulation when found in high salinity. Temperature elevation (20 degrees C-* 24.3 degrees C) caused a slight increase in hemolymph osmolality but did not disrupt the osmotic regulatory pattern. In crabs, salinity was the main factor in osmotic regulation (20%o-* 40%o), given the hyper-hyposmoregulation profile observed in low and high salinity conditions, respectively, regardless of temperature. Both species showed significant changes in hemolymph inorganic ion concentrations and in the activity of osmoregulatory and calcification-related enzymes, indicating physiological challenges in maintaining these elements under thermal and/or saline stress. Notably, the combined effects of global warming and salinity stress appear to impair calcification in the yellow clam, as evidenced by reduced enzymatic activity associated with calcium carbonate formation. In contrast, in the crab, decreased enzymatic activity was primarily driven by salinity, suggesting that osmotic stress may represent a greater constraint on calcification in this species.
Seagrass meadows are rapidly declining worldwide, and restoration is challenging in altered ecosystems impacted by human and climate-driven changes. Predicting suitable habitats for restoration is particularly difficult in dynamic systems with fluctuating stressors. We examined the ecophysiological limits of eelgrass (Zostera marina) from the Limfjord (Denmark) using a 12-week controlled multi-stressor mesocosm experiment. We tested three mean salinities (20, 28, 31), a salinity regime factor (constant vs. fluctuating +/- 6, applied only to the 20 and 28 treatments, with 1.25 fluctuation cycles), and two light levels (ambient and 65% reduced), based on the Dutch Wadden Sea, where similar to 150 km(2) of eelgrass has been lost. Salinity fluctuations did not directly impact eelgrass morphology but did influence physiological traits and biomass investment patterns, leading to thicker leaves, heavier shoots, and increased rhizome sucrose. The 65% light reduction was the dominant stressor, causing substantial declines in shoot numbers (-44%), leaf numbers (-50%), and aboveground biomass (-34%). Constant salinity levels affected leaf area per aboveground weight, shoot mass, and leaf C:N ratios. Medium salinity (28) supported the highest leaf surface area, belowground biomass, and leaf numbers under ambient light. Our findings suggest that eelgrass can tolerate multi-week-scale salinity fluctuations ex situ, but light availability is important for survival and strongly influences the morphology. In the Dutch Wadden Sea, for the highest eelgrass growth, we recommend targeting sites with moderate salinity (28) and light levels >= 200 mu mol photons m(-2) s(-1). These results can refine knowledge-based site selection for eelgrass restoration.
Phototrophic and heterotrophic symbionts are associated with marine sponges and are presumed to provide sustenance to the host, though the precise relationship between partners is poorly understood. Whether those symbiotic partnerships influence the host's feeding behavior through, for example, different strategies for prey capture or through reduced reliance on heterotrophy, is poorly studied. We examined the trophic specialization of three species of sponge with similar, branching morphologies that co-occur in near-shore, shallow sand flats of the lower Florida Keys. Each species associates with different photosymbionts. Cliona varians forma varians harbors populations of the dinoflagellate Gerakladium spongiolum. Both Ircinia cf. reteplana and Neopetrosia subtriangularis harbor populations of cyanobacteria that likely belong to different clades of “Candidatus Synechococcus spongiarum.” A pulse:chase experiment indicated that the species appear to differ in their reliance on the translocation of photosynthates from symbionts. Significant differences among the three species in bulk stable isotope signatures indicate different trophic statuses and thus different heterotrophic strategies. Tissue-associated microbiomes differed among the species, as did pumping rates and filtration behaviors. Taken together, the results suggest that when controlling for environment and morphology, symbionts may drive the feeding ecology of the holobiont, including differential reliance on translocated photosynthate from symbionts and the potential for differential capture of specific members of bacterioplankton. As sponges are ecologically important members of shallow reef habitats and an important benthic-pelagic coupling link, it is imperative to better understand the role that symbionts play in the host's trophic performance, including whether symbiosis drives specialized predatory behaviors.
