Interspecific variation in life history relates to antipredator decisions by marine mesopredators on temperate reefs

As upper-level predatory fishes become overfished, mesopredators rise to become the new 'top' predators of over-exploited marine communities. To gain insight into ensuing mechanisms that might alter indirect species interactions, we examined how behavioural responses to an upper-level predatory fish might differ between mesopredator species with different life histories. In rocky reefs of the northeast Pacific Ocean, adult lingcod (Ophiodon elongatus) are upper-level predators that use a sit-and-wait hunting mode. Reef mesopredators that are prey to adult lingcod include kelp greenling (Hexagrammos decagrammus), younger lingcod, copper rockfish (Sebastes caurinus) and quillback rockfish (S. maliger). Across these mesopredators species, longevity and age at maturity increases and, consequently, the annual proportion of lifetime reproductive output decreases in the order just listed. Therefore, we hypothesized that the level of risk taken to acquire resources would vary interspecifically in that same order. During field experiments we manipulated predation risk with a model adult lingcod and used fixed video cameras to quantify interactions between mesopredators and tethered prey (Pandalus shrimps). We predicted that the probabilities of inspecting and attacking tethered prey would rank from highest to lowest and the timing of these behaviours would rank from earliest to latest as follows: kelp greenling, lingcod, copper rockfish, and quillback rockfish. We also predicted that responses to the model lingcod, such as avoidance of interactions with tethered prey, would rank from weakest to strongest in the same order. Results were consistent with our predictions suggesting that, despite occupying similar trophic levels, longer-lived mesopredators with late maturity have stronger antipredator responses and therefore experience lower foraging rates in the presence of predators than mesopredators with faster life histories. The corollary is that the fishery removal of top predators, which relaxes predation risk, could potentially lead to stronger increases in foraging rates for mesopredators with slower life histories.     

Application of Acoustic Telemetry to Assess Residency and Movements of Rockfish and Lingcod at Created and Natural Habitats in Prince William Sound

Loss and/or degradation of nearshore habitats have led to increased efforts to restore or enhance many of these habitats, particularly those that are deemed essential for marine fishes. Copper rockfish (Sebastes caurinus) and lingcod (Ophiodon enlongatus) are dominant members of the typical reef fish community that inhabit rocky and high-relief substrates along the Pacific Northwest. We used acoustic telemetry to document their residency and movements in the nearshore waters of Prince William Sound, Alaska in order to assess use of created reef habitat in an individual-based manner. A total of 57 fish were surgically implanted with acoustic transmitters. Forty-five fish were captured and monitored in three habitats: artificial reef, low-relief natural reef, and patchy high-relief natural reef. Within each habitat, both rockfish and lingcod exhibited long periods of residency with limited movements. Twelve rockfish were captured at the natural reefs and displaced a distance of 4.0 km to the artificial reef. Five of the 12 rockfish returned within 10 d of their release to their initial capture site. Another five of the 12 displaced fish established residency at the artificial reef through the duration of our study. Our results suggest the potential for artificial reefs to provide rockfish habitat in the event of disturbances to natural habitat.     

Lagenidium myophilum infection in the coonstripe shrimp,Pandalus hypsinotus

A fungal infection occurred in juvenile coonstripe shrimps,Pandalus hypsinotus, cultured at Hokkaido Institute of Mariculture, Hokkaido, Japan. The fungus was identified asLagenidium myophilum, the same fungus that had previously been isolated from the abdominal muscle of adult northern shrimps,Pandalus borealis, and larvae of the coonstripe shrimp. Histopathologically, numerous nonseptate hyphae were observed in the lesions, and melanized hemocytes were present within the blackened areas. The optimum temperature for growth of the present strain was 25–30°C, and the optimum NaCl concentration for growth was 0.5–1.0%. Its biological characteristics were compared with those ofLagenidium myophilum isolated from diseased larval coonstripe shrimp and adult northern shrimp. The fungus was pathogenic toward shrimps of the genusPandalus, which live in deep sea areas. The fungus could infect shrimps at various stages, from larva to adult.     

Structural complexity in relation to the habitat preferences,territoriality, and hatchery rearing of juvenile China rockfish (<Emphasis Type="Italic">Sebastes nebulosus</Emphasis>)

Conservation efforts require an understanding of the basic behavior and ecology of target species. However, limited information exists for a wide range of taxa, including declining species of rockfish (genus Sebastes). First, we observed captive juvenile China rockfish (S. nebulosus) to determine how they interact with their environment and conspecifics. Juveniles exhibited site fidelity and territoriality. These aggressive interactions occurred within the context of size-biased dominance, centered on competition for structurally complex habitat. Given the apparent importance of structure and the absence of structure in typical hatchery environments, we then asked how the absence of structure affects future behavior. When barren-reared and structure-reared juveniles were combined into a structurally complex aquarium, barren-reared fish displayed less structure use and less site fidelity than structure-reared fish. However, after 1 to 2 weeks, barren-reared fish began to use structure and showed site fidelity that eventually equaled that of structure-reared juveniles, showing that those behavioral effects of the rearing environment were not permanent. Though these short-term effects may still impact survival after hatchery release, we were unable to detect significant effects on vulnerability to a predator (lingcod, Ophiodon elongatus) in laboratory trials.     

Effects of hypoxia on the behavior and physiology of kelp forest fishes

Forecasts from climate models and oceanographic observations indicate increasing deoxygenation in the global oceans and an elevated frequency and intensity of hypoxic events in the coastal zone, which have the potential to affect marine biodiversity and fisheries. Exposure to low dissolved oxygen (DO) conditions may have deleterious effects on early life stages in fishes. This study aims to identify thresholds to hypoxia while testing behavioral and physiological responses of two congeneric species of kelp forest fish to four DO levels, ranging from normoxic to hypoxic (8.7, 6.0, 4.1, and 2.2 mg O₂/L). Behavioral tests identified changes in exploratory behavior and turning bias (lateralization), whereas physiological tests focused on determining changes in hypoxia tolerance (pCrit), ventilation rates, and metabolic rates, with impacts on the resulting capacity for aerobic activity. Our findings indicated that copper rockfish (Sebastes caurinus) and blue rockfish (Sebastes mystinus) express sensitivity to hypoxia; however, the strength of the response differed between species. Copper rockfish exhibited reduced absolute lateralization and increased escape time at the lowest DO levels, whereas behavioral metrics for blue rockfish did not vary with oxygen level. Both species exhibited decreases in aerobic scope (as a function of reduced maximum metabolic rate) and increases in ventilation rates to compensate for decreasing oxygen levels. Blue rockfish had a lower pCrit and stronger acclimation response compared to copper rockfish. The differences expressed by each species suggest that acclimatization to changing ocean conditions may vary, even among related species that recruit to the same kelp forest habitat, leading to winners and losers under future ocean conditions. Exposure to hypoxia can decrease individual physiological fitness through metabolic and aerobic depression and changes to anti‐predator behavior, with implications for the outcome of ecological interactions and the management of fish stocks in the face of climate change.     

Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers

Background

Fairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers Dry Lakes. We surveyed branchiopods during the wet season to estimate abundances and then conducted a laboratory microcosm experiment, in which dried sediment containing cysts and the overlying algal crust were inundated and cultured. Microcosm trials were run with and without shrimps; each type of trial was run for two lengths of time: 30 and 60 days. We estimated the effect of shrimps on algae by measuring chlorophyll content and the relative abundance of algal species.

Results

We found two species of fairy shrimps (Branchinecta mackini and B. gigas), one tadpole shrimp (Lepidurus lemmoni), and a clam shrimp (Cyzicus setosa) in our wet-season field survey. We collected Branchinecta lindahli in a pilot study, but not subsequently. The dominant taxa were C. setosa and B. mackini, but abundances and species composition varied greatly among playas. The same species found in field surveys also occurred in the microcosm experiment. There were no significant differences as a function of experimental treatments for either chlorophyll content or algal species composition (Microcoleus vaginatus dominated all treatments).

Conclusions

The results suggest that there was no direct effect of shrimps on algae. Although the pans harbored an apparently high abundance of branchiopods, these animals had little role in regulating primary producers in this environment.     

Habitat-based submersible assessment of macro-invertebrate and groundfish assemblages at Heceta Bank, Oregon, from 1988 to 1990

Exploitation of groundfish off the U.S. Pacific coast reached maximum levels during the 1990s, resulting in severe declines in at least nine species of groundfish. From 1988 to 1990, we used the 2-man submersible Delta to make 42 dives and run replicate visual belt transects at six stations ranging from 67-360 m in depth at Heceta Bank on the outer continental shelf of Oregon. We identified four major habitats and associated benthic macroinvertebrate and groundfish assemblages: (1) shallow rock ridges and large boulders (< 100 m deep) dominated by basket stars, juvenile rockfishes, yelloweye rockfish, and lingcod; (2) mid-depth small boulder-cobbles (100-150 m) dominated by crinoids, brittle stars, rosethorn, pygmy/Puget sound, and canary rockfishes; (3) deep cobble (150-200 m) dominated by crinoids, brittle stars and various small rockfish species, and (4) deep mud slope (> 200 m) dominated by fragile urchins, sea cucumbers, shortspine thornyhead, and flatfishes. Although substantial interannual variation in groundfish abundance among seafloor types was evident in the 12 most abundant and/or commercially important fish taxa sampled, high variance resulted in statistically significant differences among years only in juvenile rockfishes. These data provide a baseline for future comparisons exploring long-term change this continental-shelf ecosystem.     

Polygamous Mating and High Levels of Genetic Variation in Lingcod, Ophiodon elongatus, of the Strait of Georgia, British Columbia

Lingcod, Ophiodon elongatus, is a nest-guarding marine fish of western North America. Breeding occurs in late winter and early spring after males establish territories and guard nest sites therein. Eggs deposited as clutches in the nest site hatch ～7 weeks after fertilization. We evaluated the level of genetic variation in lingcod spawning in the central Strait of Georgia through analysis of microsatellite and mitochondrial D-loop variability in fertilized egg samples collected from guarded clutches. Reconstructed parental genotypes displayed a high level of allelic diversity and observed heterozygosity (83–91%) over five microsatellite loci. Progeny of a single clutch were invariably derived from a single mother and between one and five fathers. Multiple egg samples were collected from inside and outside positions on 13 lingcod egg clutches in February 2002. Fin clip samples provided microsatellite genotypes for six of the nine guardian males. Analysis of between 33 and 306 eggs from each clutch indicated that each of the 13 clutches was produced by a different mother and five of them were sired entirely by the attendant male guardian. Eight clutches were sired by multiple males, with neighboring male guardians frequently involved in clutch fertilization. Known guardian males accounted for at least 78% of observed egg fertilization, although non-territorial males were observed and may have participated in spawning. Egg fertilization by individual males was spatially heterogeneous throughout egg clutches. One male guardian failed to fertilize detectable numbers of eggs in his own or any other clutch within the study area and may have been an adoptive father. The polygynous mating structure of lingcod may help maintain genetic variation in the species.     

Role of olfaction and vision in homing behaviour of black rockfish Sebastes inermis

How fish find their original habitat and natal home remains an unsolved riddle of animal behaviour. Despite extensive efforts to study the homing behaviour of diadromous fish, relatively little attention has been paid to that of non-diadromous marine fish. Among these, most rockfish of the genus Sebastes exhibit homing ability and/or a strong fidelity to their habitats. However, how these rockfish detect the homeward direction has not been clarified. The goal of the present research was to investigate the sensory mechanisms involved in the homing behaviour of the black rockfish Sebastes inermis, using acoustic telemetry. Vision-blocked or olfactory-ablated rockfish were released in natural waters and their homing behaviours compared with those of intact or control individuals. Blind rockfish showed homing from both inside and outside their habitat. The time taken by blind fish to reach their home habitat was not significantly different from that of the control fish. In contrast, most olfactory-ablated fish did not successfully reach their original habitat. Our results indicate that black rockfish predominantly use the olfactory sense in their homing behaviour.     

Use of Microsatellite Locus Flanking Regions for Phylogenetic Analysis? A Preliminary Study of Sebastes subgenera

The systematics of the species-rich genus of Sebastes rockfish has not been resolved, and is unlikely to be resolved using morphological criteria. Using an alternative approach based on DNA sequence variation, we sampled the genome for random, presumably neutral, nuclear DNA sequences, by sequencing microsatellite flanking regions of 15 Sebastes species (representing 15 of 22 extant subgenera) and Hozukius emblemarius. We aligned sequences of flanking regions of eight of the 13 loci that amplified, which presumably are homologous. In aggregate, the aligned sequences included 848 bp, 53 bp of which were polymorphic. The base changes among species included 27 transitions, 20 transversions, three multiple substitutions, and three deletions or insertions. The flanking regions at different loci had different base substitution rates. Nucleotide divergence among Sebastes species ranged from 0.0012 to 0.0216, whereas nucleotide divergence between Sebastes and Hozukius species ranged from 0.0095 to 0.0240. We used maximum parsimony, neighbor-joining, and maximum likelihood methods to examine relationships among the species. H. emblemariusformed a separate group, and five of the western Pacific Ocean species of rockfish clustered together, suggesting that they may have shared an evolutionary history distinct from many North American species. The flanking regions of some microsatellite loci contain DNA sequence variation that distinguishes rockfish species and may prove useful for clarifying relationships among rockfish, or other closely related species.     

Salinity-dependent modulation by protein kinases and the FXYD2 peptide of gill (Na+, K+)-ATPase activity in the freshwater shrimp Macrobrachium amazonicum (Decapoda,Palaemonidae)

The geographical distribution of aquatic crustaceans is determined by ambient factors like salinity that modulate their biochemistry, physiology, behavior, reproduction, development and growth. We investigated the effects of exogenous pig FXYD2 peptide and endogenous protein kinases A and C on gill (Na⁺, K⁺)-ATPase activity, and characterized enzyme kinetic properties in a freshwater population of Macrobrachium amazonicum in fresh water (<0.5 ‰ salinity) or acclimated to 21 ‰S. Stimulation by FXYD2 peptide and inhibition by endogenous kinase phosphorylation are salinity-dependent. While without effect in shrimps in fresh water, the FXYD2 peptide stimulated activity in salinity-acclimated shrimps by ≈50 %. PKA-mediated phosphorylation inhibited gill (Na⁺, K⁺)-ATPase activity by 85 % in acclimated shrimps while PKC phosphorylation markedly inhibited enzyme activity in freshwater- and salinity-acclimated shrimps. The (Na⁺, K⁺)-ATPase in salinity-acclimated shrimp gills hydrolyzed ATP at a V_max of 54.9 ± 1.8 nmol min^?1 mg^?1 protein, corresponding to ≈60 % that of freshwater shrimps. Mg²⁺ affinity increased with salinity acclimation while K⁺ affinity decreased. (Ca²⁺, Mg²⁺)-ATPase activity increased while V(H⁺)- and Na⁺- or K⁺-stimulated activities decreased on salinity acclimation. The 120-kDa immunoreactive band expressed in salinity-acclimated shrimps suggests nonspecific α-subunit phosphorylation by PKA and/or PKC. These alterations in (Na⁺, K⁺)-ATPase kinetics in salinity-acclimated M. amazonicum may result from regulatory mechanisms mediated by phosphorylation via protein kinases A and C and the FXYD2 peptide rather than through the expression of a different α-subunit isoform. This is the first demonstration of gill (Na⁺, K⁺)-ATPase regulation by protein kinases in freshwater shrimps during salinity challenge.     

Positive Effects of Plant Genotypic and Species Diversity on Anti-Herbivore Defenses in a Tropical Tree Species

Despite increasing evidence that plant intra- and inter-specific diversity increases primary productivity, and that such effect may in turn cascade up to influence herbivores, there is little information about plant diversity effects on plant anti-herbivore defenses, the relative importance of different sources of plant diversity, and the mechanisms for such effects. For example, increased plant growth at high diversity may lead to reduced investment in defenses via growth-defense trade-offs. Alternatively, positive effects of plant diversity on plant growth may lead to increased herbivore abundance which in turn leads to a greater investment in plant defenses. The magnitude of trait variation underlying diversity effects is usually greater among species than among genotypes within a given species, so plant species diversity effects on resource use by producers as well as on higher trophic levels should be stronger than genotypic diversity effects. Here we compared the relative importance of plant genotypic and species diversity on anti-herbivore defenses and whether such effects are mediated indirectly via diversity effects on plant growth and/or herbivore damage. To this end, we performed a large-scale field experiment where we manipulated genotypic diversity of big-leaf mahogany (Swietenia macrophylla) and tree species diversity, and measured effects on mahogany growth, damage by the stem-boring specialist caterpillar Hypsipyla grandella, and defensive traits (polyphenolics and condensed tannins in stem and leaves). We found that both forms of plant diversity had positive effects on stem (but not leaf) defenses. However, neither source of diversity influenced mahogany growth, and diversity effects on defenses were not mediated by either growth-defense trade-offs or changes in stem-borer damage. Although the mechanism(s) of diversity effects on plant defenses are yet to be determined, our study is one of the few to test for and show producer diversity effects on plant chemical defenses.     

Reproductive biology of the sea anemone shrimp Periclimenes rathbunae (Caridea,Palaemonidae, Pontoniinae), from the Caribbean coast of Costa Rica

Caridean shrimps are a highly diverse group and many species form symbiotic relationships with different marine invertebrates. Periclimenes rathbunae is a brightly colored shrimp that lives predominantly in association with sea anemones. Information about the reproductive ecology of the species is scarce. Therefore, we collected 70 ovigerous females inhabiting the sun sea anemone Stichodactyla helianthus in coral reefs from the southern Caribbean coast of Costa Rica. Females produced on average 289 ± 120 embryos. The volume of recently-produced embryos was on average 0.038 mm³, and embryo volume increased by 192% during the incubation period. The average embryo mortality during embryogenesis was 24%. The reproductive output was 0.24 ± 0.094, considerably higher than in many other pontoniine shrimps. Females carrying embryos close to hatching showed fully developed ovaries, suggesting consecutive spawning. We assume that the sheltered habitat, living on sea anemones, allows Periclimenes rathbunae to allocate more energy in embryo production than most other free-living caridean shrimps. This is the first record of Periclimenes rathbunae for Costa Rica.     

Patterns of assemblage change in prairie stream fishes in relation to urban stormwater impoundments

The effects of stream urbanization on fishes have been well studied in general. Yet despite the wealth of knowledge available for streams in many different ecoregions, relatively little is known of the effects of urbanization on prairie stream fishes. Management of urban stormwater through impoundment has the potential to fragment streams, and habitat fragmentation on nonurban streams has been documented to relate to declines in small-bodied mobile minnow species. We asked whether urban habitat fragmentation through stormwater impoundment would relate to a similar decline in small-bodied fishes in Cottonwood Creek, a stream system partially managed by stormwater impoundment in central Oklahoma. Analyses with basic metrics of ecological tolerance, richness, community structure, and multivariate ordination found negative relationships between cyprinid richness and abundance and a metric of urban habitat fragmentation, as well as between Lepomis humilis, a small-bodied sunfish, and the metric of urban habitat fragmentation. We review potential hypotheses for these biological patterns in fragmented urban streams, including predation, lack of successful reproduction, and lack of ability to recolonize above barriers.     

Climatic forcing and larval dispersal capabilities shape the replenishment of fishes and their habitat‐forming biota on a tropical coral reef

Fluctuations in marine populations often relate to the supply of recruits by oceanic currents. Variation in these currents is typically driven by large‐scale changes in climate, in particular ENSO (El Nino Southern Oscillation). The dependence on large‐scale climatic changes may, however, be modified by early life history traits of marine taxa. Based on eight years of annual surveys, along 150 km of coastline, we examined how ENSO influenced abundance of juvenile fish, coral spat, and canopy‐forming macroalgae. We then investigated what traits make populations of some fish families more reliant on the ENSO relationship than others. Abundance of juvenile fish and coral recruits was generally positively correlated with the Southern Oscillation Index (SOI), higher densities recorded during La Niña years, when the ENSO‐influenced Leeuwin Current is stronger and sea surface temperature higher. The relationship is typically positive and stronger among fish families with shorter pelagic larval durations and stronger swimming abilities. The relationship is also stronger at sites on the coral back reef, although the strongest of all relationships were among the lethrinids (r = .9), siganids (r = .9), and mullids (r = .8), which recruit to macroalgal meadows in the lagoon. ENSO effects on habitat seem to moderate SOI–juvenile abundance relationship. Macroalgal canopies are higher during La Niña years, providing more favorable habitat for juvenile fish and strengthening the SOI effect on juvenile abundance. Conversely, loss of coral following a La Niña‐related heat wave may have compromised postsettlement survival of coral dependent species, weakening the influence of SOI on their abundance. This assessment of ENSO effects on tropical fish and habitat‐forming biota and how it is mediated by functional ecology improves our ability to predict and manage changes in the replenishment of marine populations.     

Limited realized dispersal and introgressive hybridization influence genetic structure and conservation strategies for brown rockfish, <Emphasis Type="Italic">Sebastes auriculatus</Emphasis>

Understanding patterns of connectivity among marine fish populations with demersal adults and pelagic larvae is critical for effective conservation of west coast rockfishes. The brown rockfish (Sebastes auriculatus) occurs in nearshore habitat and is common from northern Baja California, Mexico to northern California, rare off the outer coast of Oregon and Washington and again common in the inland waters of Puget Sound, Washington. Here we examine patterns of microsatellite DNA diversity from throughout the species’ range as an indirect measure of long-term trends in larval dispersal. Genetic divergence was large and highly significant over all populations (F _ST=0.056, P<0.0001), and was significantly correlated with geographic distance when considering coastal populations. The best estimates of mean coastal dispersal distance were on the order of 10 km or less per generation. Diversity was relatively low in the Puget Sound, suggesting that Puget Sound rockfish populations experienced a post-glacial founder effect followed by genetic isolation and low effective population size. Puget Sound individuals appeared to have recent mixed ancestry as a result of introgression with S. maliger and S. caurinus. Genetic isolation of Puget Sound fish provides a basis for consideration as a Distinct Population Segment (DPS) under the provisions of the Endangered Species Act. We recommend that coastal brown rockfish fisheries be managed at regional rather than coast-wide scales, and that design of marine reserve networks considers the surprisingly low realized dispersal distance of some species with high dispersal potential.     

Movements of hatchery-reared lingcod released on rocky reefs in Puget Sound

Fourteen sub-adult hatchery-reared lingcod (Ophiodon elongatus) were released onto reefs in South Puget Sound, Washington, USA to evaluate their movement behavior. Acoustic telemetry revealed variation in movement among individuals that was related to body size. Larger lingcod tended to leave the release reef sooner than smaller lingcod. Four lingcod left the reefs less than 10 days after release, while three lingcod left between one and 4 months after release. Seven lingcod remained at the release reefs for the entire 5-month study, though they did make apparent short-term (< 24 h duration) excursions away from the reefs. Data suggest that the frequency and duration of excursions increase with age and size in both wild and hatchery lingcod. Movement data from these hatchery lingcod and previously published studies on wild lingcod are compared.     

Small but Powerful: Top Predator Local Extinction Affects Ecosystem Structure and Function in an Intermittent Stream

Top predator loss is a major global problem, with a current trend in biodiversity loss towards high trophic levels that modifies most ecosystems worldwide. Most research in this area is focused on large-bodied predators, despite the high extinction risk of small-bodied freshwater fish that often act as apex consumers. Consequently, it remains unknown if intermittent streams are affected by the consequences of top-predators’ extirpations. The aim of our research was to determine how this global problem affects intermittent streams and, in particular, if the loss of a small-bodied top predator (1) leads to a ‘mesopredator release’, affects primary consumers and changes whole community structures, and (2) triggers a cascade effect modifying the ecosystem function. To address these questions, we studied the top-down effects of a small endangered fish species, Barbus meridionalis (the Mediterranean barbel), conducting an enclosure/exclosure mesocosm experiment in an intermittent stream where B. meridionalis became locally extinct following a wildfire. We found that top predator absence led to ‘mesopredator release’, and also to ‘prey release’ despite intraguild predation, which contrasts with traditional food web theory. In addition, B. meridionalis extirpation changed whole macroinvertebrate community composition and increased total macroinvertebrate density. Regarding ecosystem function, periphyton primary production decreased in apex consumer absence. In this study, the apex consumer was functionally irreplaceable; its local extinction led to the loss of an important functional role that resulted in major changes to the ecosystem’s structure and function. This study evidences that intermittent streams can be affected by the consequences of apex consumers’ extinctions, and that the loss of small-bodied top predators can lead to large ecosystem changes. We recommend the reintroduction of small-bodied apex consumers to systems where they have been extirpated, to restore ecosystem structure and function.