Significant Interspecific Differences Research Articles

Ecological and evolutionary preconditions of extended longevity in subterranean rodents

According to the evolutionary theory of aging, a low level of extrinsic mortality, i.e., a low probability of the early death of animals, promotes an increase in the maximum lifespan. The subterranean rodents that dwell in well-protected environment, live longer than the terrestrial species. In the social African mole rat species with reproductive division of labor, the mortality of workers in wildlife is considerably higher than in breeders, while significant interspecific differences in the lifespan patterns may emerge in captivity. The lifespans of different castes in the family groups of the naked mole rat (Heterocephalus glaber) in captivity are almost equal. However, the breeders of another social species, the Ansell’s mole rat (Fukomys anselli), on the average live twice as long as workers. A possible explanation for the observed differences can be associated with the species specificity in their social organization, first and foremost, the mechanisms responsible for reproductive skew. A unique feature of the naked mole rat is tolerance for incest, which theoretically equalizes the chances of all individuals to be a breeder within the native family. In other social mole rat species, which avoids inbreeding, the only possibility for reproduction is dispersal. In captivity, the inability to leave the maternal family may cause the suppression of homeostatic functions responsible for longevity.

Acoustic characteristics of a native anuran (Amphibia) assemblage in a palustrine herbaceous wetland from Puerto Rico

Abstract: We documented patterns of microhabitat use, relative species abundance, and acoustic characteristics of a Puerto Rican native anuran assemblage from a palustrine herbaceous wetland. We found significant interspecific differences in the spatial distribution of calling males among microhabitat types, which differed in percent cover, height, and physical structure. The spectrogram revealed no acoustic interspecific overlap of calls above 3.0 kHz and a significant inverse relationship between body size and frequency of call. Most calls were between 4.0 kHz and 8.5 kHz range, indicative of a small-sized species assemblage. Diel calling activity patterns showed considerable interspecific overlap with most calling activity starting at approximately 16:30 hrs and decreasing after 23:30 hrs. In general, acoustic communication seems enhanced by interactions between abiotic (e.g., microhabitat/vegetation type used for calling) and biotic factors (e.g., calling behavior) that reduce acoustic attenuation in this wetland environment even though calling males can be within interspecific hearing range. Key Words: acoustic partitioning, anurans, Caribbean, Coqui Llanero, Eleutherodactylus, herbaceous wetland, Leptodactylus

Leaf physiological response to light environment of three tree fern species in a Mexican cloud forest

Abstract:Abundance and physiology of three understorey tree fern species were compared in a Mexican cloud forest. We hypothesized that the distribution of species would be associated with canopy openness and leaf physiological characteristics. In gullies (1–2% full sun), Alsophila firma was abundant, Cyathea divergens was distributed in moderately open places (4–9%), and Lophosoria quadripinnata preferred more open canopy (9–30%). Although 11 leaf traits of five plants of each species growing under closed and open canopies over 1 y did not differ within species, there were significant interspecific differences. Alsophila firma had comparatively low maximum electron transport rate ETRmax (26.8 ± 1.81 μmol m−2 s−1) and ETR light saturation point (ETRLSP: 261 ± 36.1 μmol m−2 s−1), high specific leaf area (SLA), thin leaves and decreased quantum yield during a leaf desiccation experiment. Cyathea divergens had relatively high maximum quantum yield (0.84 ± 0.004), ETRmax (37.3 ± 1.8 μmol m−2 s−1) and ETRLSP (409 ± 40.0 μmol m−2 s−1). Lophosoria quadripinnata had comparatively thick leaves, low SLA, high predawn water potential, high density (606 ± 25.5 mm−2) and small length (0.026 ± 0.002 mm) stomata. The results support the hypothesis that light sensitivity shapes tree fern distribution in the cloud forest.

Trophodynamics and life-cycle strategies of the copepods Temora longicornis and Acartia longiremis in the Central Baltic Sea

Trophodynamics and life-cycle strategies of the copepods Temora longicornis and Acartia longiremis in the Baltic Sea were studied, focussing on the seasonal progression of (i) fatty acid (FA) markers in seston and females, (ii) the copepods’ condition as well as (iii) their stage compositions. Trophic marker diversity and high levels of 18:1(n29) in copepods and seston indicated omnivory for both species. Significant inter-specific and seasonal differences in markers reflected different trophic niches of both species and a seasonal succession in diet composition. Storage lipids of A. longiremis were characterized by polyunsaturated C18-FAs, and those of T. longicornis by 16:1(n27), 20:5(n23) and 22:6(n23). Diatoms were important for T. longicornis at times of peak egg production or lipid accumulation. The preference for heterotrophic prey over diatoms of A. longiremis probably reflects a prevailing ambushfeeding strategy. Triacylglycerol reserves in T. longicornis increased in autumn and probably served as a buffer against starvation during winter. Reproductive activities were low during winter and copepodite stages developed slowly. All A. longiremis copepodids were present during winter, but no lipid accumulation was observed for overwintering. Such constantly low lipid levels suggest insufficient food supply, the absence of triggers for the induction of wax ester anabolism or a populationspecific life-history trait, which does not rely on winter energy reserves, but active foraging in the winter season.

Species and mate recognition in two sympatric Grayling butterflies: Hipparchia fagi and H. hermione genava (Lepidoptera)

The main aim of this study was to investigate and compare the patterns of male courtship behaviour in Hipparchia fagi (Woodland Grayling) and H. hermione genava (Rock Grayling) in order to determine if premating barriers are involved in the reproductive isolation between the two sympatric and syntopic species. Although they show a similar pattern of sexual behaviour (perching, flight pursuit, courtship), there were significant quantitative inter-specific differences in the step Bowing. During this step, the male bashes and strokes the female antennae between his forewings on the androconial scales revealing the importance of scent stimuli in mate communication. Moreover, different signals, spanning several sensory modalities (visual, chemical, tactile stimuli) and spatio-temporal scales (during the pair flight and the courtship step), might serve as premating barriers between the two species. In particular, both males and females of H. fagi (a woodland habitat specialist) seem to take less time in recognising their conspecific partner, while H. hermione males need to spend more time in courting (and identifying) the “right” females.

Elliptic Fourier analysis of leaf shape in southern AfricanStrychnossectionDensiflorae(Loganiaceae)

Leaves can be a useful source of taxonomic information in plants particularly when flowers and fruits are absent during certain periods of the year. In this study, we applied an elliptic Fourier analysis (EFA)-based morphometric technique to assess leaf morphological divergence among four species of southern African Strychnos section Densiflorae. Using leaf specimen images from field and herbarium collections, we extracted six shape variables [i.e. principal components (PCs)] from the Fourier coefficients and used these variables to describe leaf outline among the species. Our results indicate that the symmetric component of a leaf is the main source of shape differences accounting for 90.25% of total leaf shape variation and captures the more obvious range of observed shapes. PC1 of the symmetric variables describes a wide range of visually observable leaf shape among the species. MANOVA revealed significant interspecific differences except between S. innocua and S. madagascariensis, which could not be separated by outline analysis. A cross-validated group classification suggests that S. gerrardii, with a classification rate of 88.4%, is distinct from S. madagascariensis, contrary to some taxonomic treatments. We discuss the value of geometric morphometrics at detecting subtle morphological variations and the evolutionary implications of such variations, which may be undetectable to the human eye. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 170, 542–553.

Comparative study of walking and climbing speeds among Neotropical harvestmen from Costa Rica

Abstract Relatively little is known about factors that contribute to microhabitat selection among Central American harvestmen. In this study, we compared walking and climbing speeds for five common species from Costa Rica representing the families Cosmetidae (3 species), Gonyleptidae (1 species) and Sclerosomatidae (1 species). Our sample included two arboreal species, two species that infrequently occupy perches in the vegetation, and one species that rarely climbs. Our analyses revealed no significant interspecific differences in climbing speed, although species with relatively long legs walked significantly faster than species with shorter legs. An arboreal habit did not correlate with increased climbing speed, and all species walked significantly faster than they climbed.

A new ectoparasitic Aulacothrips (Thysanoptera: Heterothripidae) from Amazon rainforest and the significance of variation in antennal sensoria

Aulacothrips amazonicus sp.n. is described from Northern Brazil, with larvae and adults ectoparasitic on ant-tended Membracidae (Hemiptera) on Solanum shrubs. This new taxon differs from its congeners by (i) body distinctively paler; (ii) sensoria on antennal segments III & IV much less convoluted; (iii) male tergite IX posterior margin straight and with several long and stout setae. The possible biological significance of interspecific differences in antennal sensoria among Aulacothrips species is discussed.

Testing Predictions of the Oxidative Stress Hypothesis of Aging Using a Novel Invertebrate Model of Longevity: The Giant Clam (Tridacna Derasa)

Bivalve species with exceptional longevity are newly introduced model systems in biogerontology to test evolutionarily conserved mechanisms of aging. Here, we tested predictions based on the oxidative stress hypothesis of aging using one of the tropical long-lived sessile giant clam species, the smooth giant clam (Tridacna derasa; predicted maximum life span: >100 years) and the short-lived Atlantic bay scallop (Argopecten irradians irradians; maximum life span: 2 years). The warm water-dwelling giant clams warrant attention because they challenge the commonly held view that the exceptional longevity of bivalves is a consequence of the cold water they reside in. No significant interspecific differences in production of H2O2 and O2- in the gills, heart, or adductor muscle were observed. Protein carbonyl content in gill and muscle tissues were similar in T derasa and A i irradians. In tissues of T derasa, neither basal antioxidant capacities nor superoxide dismutase and catalase activities were consistently greater than in A i irradians. We observed a positive association between longevity and resistance to mortality induced by exposure to tert-butyl hydroperoxide (TBHP). This finding is consistent with the prediction based on the oxidative stress hypothesis of aging. The findings that in tissues of T derasa, proteasome activities are significantly increased as compared with those in tissues of A i irradians warrant further studies to test the role of enhanced protein recycling activities in longevity of bivalves.

Mercury Concentration in the Spectacled Caiman and Black Caiman (Alligatoridae) of the Amazon: Implications for Human Health

Mercury (Hg) concentrations in the Amazon are generally high, but no studies have been published on Hg concentrations in caimans (Alligatoridae) from the region. Aiming for sizes representative of caimans traded for food in the Amazon, we measured Hg concentration in tail muscle of spectacled caiman (Caiman crocodilus crocodilus) and black caiman (Melanosuchus niger) from the Purus River basin. The information on Hg concentration in caimans from this area is important because of the potential health risk to humans and other animals that eat them as well as the potential use of these top-level predators as bioindicators. There were no significant interspecific or sex differences in Hg concentrations. The mean Hg concentration was 291.2 μg/kg in C. c. crocodilus and 193.9 μg/kg in M. niger. A significant positive correlation between Hg concentration and size was found for M. niger (p = 0.005) but not for C. c. crocodilus. Our Hg sample from M. niger corresponded to the size of M. niger collected for commercial trade, but our Hg sample from C. c. crocodilus turned out to be significantly smaller than the trade samples (p = 0.004), but this difference is not pertinent in the absence of a correlation between size and Hg concentration for this species. Although there are no standards for reptile meat, both species had mean Hg concentrations lower than the maximum allowable level of 500 μg/kg Hg recommended by the World Health Organization and by the Brazilian Health Ministry for fish. However, by calculating daily consumptions limits and number of meals per month that can be safely consumed, we found that consumers who eat caimans frequently may be at risk for Hg-related health problems.

Swimming performance of two Iberian cyprinids: the Tagus nase Pseudochondrostoma polylepis (Steindachner, 1864) and the bordallo Squalius carolitertii (Doadrio, 1988)

Summary The main purpose of this study was to gather swimming performance information for two endemic cyprinids of the Iberian Peninsula to contribute to the optimization of fish ways. Critical swimming speed (Ucrit) was determined for the Tagus nase Pseudochondrostoma polylepis (Steindachner, 1864) and for the bordallo Squalius carolitertii (Doadrio, 1988) in a swimming tunnel. From a total of 80 P. polylepis tested, the mean (± SD) Ucrit observed was 0.78 ± 0.15 ms−1 (c. 3.74 ± 0.93 BL s−1); the 68 S. carolitertii tested presented an Ucrit of 0.54 ± 0.1 ms−1 (c. 4.43 ± 0.74 BL s−1). Significant interspecific differences were found between the Ucrit of the tested cyprinids. Intraspecific comparisons between the Ucrit and the variables of size, sex, condition factor and gonado-somatic index were also made. No sex-or gonad maturation-related differences between the Ucrit were identified, but the robust P. polylepis were found to be stronger swimmers. Water velocities in fish ways for P. polylepis and S. carolitertii should aim, on average, for lower than 0.7 and 0.5 ms−1, respectively.

Functional characteristics of traps of aquatic carnivorous Utricularia species

Firing and resetting of traps in aquatic Utricularia species are associated with water flow and trap volume changes. In this study, trap thickness was used as a measure of water flow and was monitored automatically using an electronic position sensor. The basic characteristics of mechanically stimulated firing and resetting were measured in isolated traps from 13 aquatic Utricularia species and in two trap size categories in Utricularia reflexa. This allowed to study the relationship between these trap functions and trap thickness and length (criteria of trap size). Additionally, the characteristics of spontaneous firings (without any mechanical stimulation) were compared for U. reflexa traps fed or denied prey during a 1-day period. On the absolute scale, the 13 Utricularia species differed considerably in their firing and resetting rates. Significant interspecific differences were also found in the magnitude of firing (in total 3.7–4.2 times) and resetting rates (10–24 times) per unit trap thickness or length. Overall, traps of Utricularia australis, Utricularia stellaris and Utricularia inflata showed the greatest firing and resetting rates. The relative magnitude of firing per unit trap thickness or length showed a highly significant negative correlation with both trap thickness and length and the same also held for the relative resetting rates. Smaller and narrower traps are thus relatively more effective at trap firing and resetting than larger traps. Neither firing nor resetting characteristics were significantly different between unfed and prey-fed traps of U. reflexa and this was also true for the occurrence of spontaneous firings. A strict linear resetting rate, without any lag-period, was found during the first 3 min after trap firing in U. reflexa. This suggests that water is pumped out of the trap continuously and probably recirculates. Given the concepts of spontaneous firing and water recirculation, an ecological model based on the literature data has been devised to quantify the daily N and P gain from the ambient water by Utricularia traps devoid of animal prey. The model shows that the total N and P content estimated in the trap fluid is too high to be accumulated from only the ambient water. This implies that the prey-free traps do not take up N or P from the trap fluid but rather exude a quantity of these nutrients to the fluid to support the microbial community. Therefore, the trap microorganisms behave more as parasites than commensals and represent an additional ecological cost for trap maintenance.

Toxic metals in commercial marine fish in Oman with reference to national and international standards

Commercially important fresh (581) and frozen (292) marine fish samples of 10 species were collected from seafood factories and evaluated using AAS and ICP–OES. Metal levels significantly (p<0.05) varied within and between species. However, there were no significant correlations among metals. There were significant interspecific differences for all metals, and yellowfin tuna had the highest level of cadmium and mercury however, red seabream had maximum numbers above the standards. The metal accumulation significantly varied between bottom feeders of intermediately size locally caught fish. The mean cadmium level ranged from 0.0049 to 0.036mgkg−1 and 1.37% of the total samples exceeded the EU and FAO standards. Mean lead content varied between 0.029 and 0.196mgkg−1, few samples crossed the EU (2.63%) and FAO (1.6%) limits. Mean mercury level ranged from 0.015 to 0.101mgkg−1 and none of the samples exceeded the EU limit. Of the total samples analyzed red seabream (2.06%), yellowfin tuna (1.14%), emperor (0.34%), santer bream (0.22%), king fish (0.11%) and skipjack tuna (0.11%) samples crossed the EU limits. In general, fish from these regions are within the safety levels recommended by various organizations and do not pose a health risk in terms of human diet.

To what extent are the dietary compositions of three abundant, co‐occurring labrid species different and related to latitude, habitat, body size and season?

This study demonstrated that the dietary composition of each of three abundant reef-associated labrid species in temperate Western Australia differed significantly with latitude and changed with increasing body size and almost invariably differed among those species when they co-occurred. These results were derived from comparisons and multivariate analyses of volumetric dietary data, obtained from the foregut contents of Coris auricularis, Notolabrus parilus and Ophthalmolepis lineolatus from the Jurien Bay Marine Park (JBMP) and waters off Perth, 250 km to the south. Latitudinal differences in the dietary compositions of each species in exposed reefs typically reflected greater contributions by large crustaceans, bivalve molluscs, echinoids and annelids to the diets in the waters off Perth than in the JBMP, whereas the reverse was true for gastropods and small crustaceans. The diet of each species exhibited similar, but not identical, quantitative changes with increasing body size, with the contributions of small crustaceans declining and those of large crustaceans and echinoids increasing, while that of gastropods underwent little change. Within the JBMP, the dietary compositions of both C. auricularis and N. parilus were similar in exposed and sheltered reefs and the same was true for N. parilus in the sheltered reefs and interspersed areas of seagrass. The latter similarity demonstrated that, in both of those divergent habitat types, N. parilus feeds on prey associated with either the sand or the macrophytes that cover and lie between the reefs. Although the main dietary components of each species were the same, i.e. gastropods, small crustaceans (mainly amphipods and isopods), large crustaceans (particularly penaeids and brachyuran crabs) and echinoids, their contributions varied among those species, which accounts for the significant interspecific differences in diet. Coris auricularis had the most distinct diet, due mainly to an ingestion of greater volumes of small crustaceans, e.g. amphipods and isopods, and lesser volumes of large crustaceans, e.g. brachyuran crabs, which was associated with a relatively narrower mouth and smaller teeth and the absence of prominent canines at the rear of the jaw. The above intra and interspecific differences in dietary composition would reduce, on the south-west coast of Australia, the potential for competition for food among and within these three abundant labrids, each of which belongs to different genera within the Julidine clade.

Comparative analysis of the structure and fauna of endosymbionts of communities of two dreissenid species (Mollusca, Dreissenidae) in the Upper Volga reservoirs

Investigations into the structure of communities of two dreissenid species are presented (native Dreissena polymorpha Pallas, 1771, and invasive D. bugensis Andrusov, 1897) in the Gorky and Rybinsk reservoirs (the Upper Volga basin). Significant interspecific and interpopulational differences in the main quantitative parameters and the fauna of endosymbionts are revealed between these mollusks.

Survival of freezing by hydrated tardigrades inhabiting terrestrial and freshwater habitats

The seasonality and unpredictability of environmental conditions at high altitudes and latitudes govern the life cycle patterns of organisms, giving rise to stresses that cause death or development of specific adaptations. Ice formation is a major variable affecting the survival of both freshwater fauna and fauna inhabiting lichens, mosses and leaf litter. Tardigrades occupy a wide range of niches in marine, freshwater and terrestrial environments. The highest number of species is found in terrestrial habitats thanks to their ability to enter anhydrobiosis and cryobiosis. The cryobiotic ability of tardigrade species from polar regions is well known. Consequently, we focused our research on the ability to survive freezing in the active hydrated state using seven tardigrade species differing in phylogenetic position and collected at various altitudes and from different habitats in a temperate area. Specimens were cooled at different cooling rates (from 0.31 °C min −1 to 3.26 °C min −1). Even though the final survival and the time required by animals to recover to active life were both inversely related to the cooling rate, highly significant interspecific differences were found. Species survival ability ranged from excellent to none. Species living in xeric habitats withstood freezing better than those living in hygrophilous habitats, while true limnic species did not exhibit any cryobiotic ability. The ability to withstand freezing seems linked to the anhydrobiotic ability. The differences in cryptobiotic performance among tardigrade species seem more influenced by selective pressures linked to local adaptation to habitat characteristics than by phylogenetic relationships.

Variation in the functioning of autonomous self-pollination, pollinator services and floral traits in three Centaurium species

Reproductive assurance through autonomous selfing is thought to be one of the main advantages of self-fertilization in plants. Floral mechanisms that ensure autonomous seed set are therefore more likely to occur in species that grow in habitats where pollination is scarce and/or unpredictable. Emasculation and pollen supplementation experiments were conducted under laboratory conditions to investigate the capacity for, and timing of autonomous selfing in three closely related Centaurium species (Centaurium erythraea, C. littorale and C. pulchellum). In addition, observations of flower visitors were combined with emasculation and pollen addition experiments in natural populations to investigate the degree of pollinator limitation and pollination failure and to assess the extent to which autonomous selfing conferred reproductive assurance. All three species were capable of autonomous selfing, although this capacity differed significantly between species (index of autonomous selfing 0·55 ± 0·06, 0·68 ± 0·09 and 0·92 ± 0·03 for C. erythraea, C. littorale and C. pulchellum, respectively). The efficiency and timing of autogamous selfing was primarily associated with differences in the degree of herkogamy and dichogamy. The number of floral visitors showed significant interspecific differences, with 1·6 ± 0·6, 5·4 ± 0·6 and 14·5 ± 2·1 floral visitors within a 2 × 2 m(2) plot per 20-min observation period, for C. pulchellum, C. littorale and C. erythraea, respectively. Concomitantly, pollinator failure was highest in C. pulchellum and lowest in C. erythraea. Nonetheless, all three study species showed very low levels of pollen limitation (index of pollen limitation 0·14 ± 0·03, 0·11 ± 0·03 and 0·09 ± 0·02 for C. erythraea, C. littorale and C. pulchellum, respectively), indicating that autonomous selfing may guarantee reproductive assurance. These findings show that limited availability of pollinators may select for floral traits and plant mating strategies that lead to a system of reproductive assurance via autonomous selfing.

Phylogeny of Sphaerium solidum (Bivalvia) based on karyotype and sequences of 16S and ITS1 rDNA

Abstract The present work represents the first karyological and molecular characterisation of Sphaerium solidum, a rare European clam. Specimens of S. solidum were collected in Lithuania and Hungary. The modal diploid chromosome number found in both populations was 2n=30. Small, biarmed B chromosomes were found in 42.3% of cells studied in clams from Lithuania and in 11.8% of cells in clams from Hungary. Comparative analysis revealed no significant (P&lt;0.05) interspecific differences in chromosome morphology of S. solidum and that of previously studied S. corneum. DNA sequence analyses of S. solidum showed no interpopulation differences in ITS1; moreover, only one site was different from ITS1 of S. corneum. However, differences in mitochondrial 16S sequence of S. solidum were revealed: two haplotypes in Lithuania and three in Hungary were identified. The genetic characteristics revealed in this study do not support ascription of S. solidum and S. corneum to different subgenus, Cyrenastrum and Sphaerium s. str., respectively. Comparative cytogenetic analysis disclosed that the chromosome morphology could be conserved in some sphaeriid species during speciation despite the fact that most other species in this family undergo radical karyotypic differentiation.

Modelling rainfall interception loss in forest restoration trials in Panama

AbstractA modified Liu analytical model of rainfall interception (Ic) by tree canopies was evaluated using rainfall, throughfall and stemflow data collected from forest restoration trials in the Republic of Panama. The model uses an introduced approach to estimating the water storage capacities of tree boles, which has a more realistic physical basis than earlier iterations of the Liu model. Study species (Acacia mangium, Gliricidia sepium, Guazuma ulmifolia, Ochroma pyramidale, and Pachira quinata) were selected on the basis of differing leaf size and crown characteristics. Significant interspecific differences in both observed and simulated cumulative interception loss were found, with A. mangium intercepting more rainfall than other species. Errors between calculated and modelled cumulative Ic ranged from + 6·3% to + 30·5%, with modelled Ic always being the larger term. During‐event evaporation rates from the study trees were positively related to tree height, crown area, and basal diameter. Crown area and the storage capacity of tree boles were negatively correlated. The results of a sensitivity analysis suggested that the modified model was most sensitive to variations in during‐event evaporation rate. The implications of the model's sensitivity to during‐event evaporation and the importance of this mechanism of interception loss are discussed, while suggestions are provided that may lead to further improvements to the analytical model. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Comparative visual function in four piscivorous fishes inhabiting Chesapeake Bay

Maintaining optimal visual performance is a difficult task in photodynamic coastal and estuarine waters because of the unavoidable tradeoffs between luminous sensitivity and spatial and temporal resolution, yet the visual systems of coastal piscivores remain understudied despite differences in their ecomorphology and microhabitat use. We therefore used electroretinographic techniques to describe the light sensitivities, temporal properties and spectral sensitivities of the visual systems of four piscivorous fishes common to coastal and estuarine waters of the western North Atlantic: striped bass (Morone saxatilis), bluefish (Pomatomus saltatrix), summer flounder (Paralichthys dentatus) and cobia (Rachycentron canadum). Benthic summer flounder exhibited higher luminous sensitivity and broader dynamic range than the three pelagic foragers. The former were at the more sensitive end of an emerging continuum for coastal fishes. By contrast, pelagic species were comparatively less sensitive, but showed larger day-night differences, consistent with their use of diel light-variant photic habitats. Flicker fusion frequency experiments revealed significant interspecific differences at maximum intensities that correlated with lifestyle and habitat. Spectral responses of most species spanned 400-610 nm, with significant day-night differences in striped bass and bluefish. Anadromous striped bass additionally responded to longer wavelengths, similar to many freshwater fishes. Collectively, these results suggest that pelagic piscivores are well adapted to bright photoclimates, which may be at odds with the modern state of eutrified coastal and estuarine waters that they utilize. Recent anthropogenic degradation of water quality in coastal environments, at a pace faster than the evolution of visual systems, may impede visually foraging piscivores, change selected prey, and eventually restructure ecosystems.