Elevated Temperatures Enhance Movement and Aggression in an Intertidal Fish.

<p>In order to gain a comprehensive understanding of population dynamics, it is vital to identify the key factors that contribute to variation in both survival and reproductive success throughout the life history of an organism. The population dynamics of reef fishes may be influenced by events occurring across multiple life stages, throughout the entire life cycle. For instance, the input of new individuals into a population (recruitment) is heavily shaped by mortality in the larval and juvenile stages, which is influenced by conspecific interactions and habitat characteristics. For individuals that survive, variation in somatic growth histories during development may influence mating success among fish that successfully recruit into the adult population, and particular developmental histories may receive a disproportionate amount of a population’s reproductive output. However, female preferences for particular phenotypes may also be modified by events occurring in adult life, such as parasite infection. Finally, absolute reproductive success (i.e., the number of offspring that survive to reproductive age) may be dependent upon early larval mortality of offspring, and variation in larval mortality among spawning sites could have consequences for metapopulation dynamics. In this thesis, I investigated how recruitment, growth and reproductive success varied among individuals of a small temperate reef fish, Forsterygion lapillum, the common triplefin, based upon their developmental histories, morphological traits, and habitat characteristics (including conspecific densities, regional locations, etc.). Specifically, I examined: - how the spatial distribution and survival of juveniles is influenced by age-class interactions (Chapter 2) - verified methods to measure somatic growth rates during development using scale structures (Chapter 3) - explored how previous growth rates influence reproductive success (Chapter 4) - evaluated how reproductive success is modified by the presence of ectoparasites (Chapter 5) - and finally, assessed how natal origin modifies larval survival probabilities among offspring (Chapter 6). The larvae of many reef fishes settle into habitats that are already occupied by adults, and interactions between age classes (intercohort interactions) may affect spatial variation in recruitment strength across settlement sites. In Chapter 2, I evaluated spatial covariation in juvenile and adult densities of F. lapillum (within the preferred settlement habitats of juveniles) to investigate correlations between adult and juvenile densities potentially caused by age-class interactions. The relationship between juvenile and adult densities followed a dome-shaped curve, with a negative correlation between juveniles and adults at higher adult densities. The shape of this curve was temporally variable, but was otherwise unaffected by particular features of the site (algal species identity). Using a laboratory-based experiment that used a “multiple predator effects” (MPE) design, I tested the hypothesis that increased settler mortality, caused by either (i) intercohort competition leading to enhanced predation risk or (ii) cannibalism by adults on juveniles, contributed to the observed negative relationship between juvenile and adult densities. Results suggested overall mortality attributable to cannibalism was low; however, smaller settlers appeared to be more vulnerable to cannibalism. There was no evidence that combined or interacting effects between predators (F. lapillum adults and Forsterygion varium [the variable triplefin]) increased predation risk in settlers of F. lapillum. Overall, these results highlight the potentially complex effects adult residents may have on shaping patterns of recruitment and the distributions of new juveniles. Somatic growth rates through ontogeny are one of the most important metrics for understanding fish populations and in Chapter 3, I evaluate the use of spacing between growth increments on fish scales (called circuli) as a measurement technique for assessing historical growth in F. lapillum. First, I established the relationship between scale growth and body size, and determined how variable this relationship was among populations. The body-scale size relationship was strongly positive and was unaffected by gender; however, there did appear to be significant differences between certain populations. Second, I monitored somatic and fish scale growth in the laboratory to measure the relationship between somatic growth and spacing between growth increments (intercirculus spacing). New scale growth and circuli deposition were both positively correlated with somatic growth. Average intercirculus spacing was also positively correlated with somatic growth rate, but this appeared to differ between age/size classes, with the older and larger individuals showing a weaker relationship. Results suggest that intercirculus spacing can be used to determine previous growth histories, but may be limited to particular size/age ranges (e.g., juveniles). In Chapter 4, I employ the techniques developed in Chapter 3 to examine how early growth rates (derived from fish scales) and male morphological traits explain variation in reproductive output between individual males in F. lapillum. I measured the reproductive success of breeding males in relation to their size and growth rates over the breeding season at two different spawning locations. Clutch size (number of eggs per nest) was highly variable among individuals over the study period; however, I detected a significant, albeit subtle, negative correlation between clutch size and growth rates after settlement. Although growth explained relatively small amounts of total variation, it was the only male trait I measured that significantly correlated with clutch size. The negative effects of faster growth on clutch size were greatest during the period of growth after settlement suggesting that growth at this early stage may be important for later reproductive success (early post-settlement). In Chapter 5, I examined how infection with an ectoparasite modified reproductive success among individual males using a field survey. Females often preferentially mate with unparasitised males, and therefore parasitised males experience lowered reproductive success. In this study, individuals of greater total length were more likely to be infected with an ectoparasite, but were also more likely to have an egg nest. Parasite infection had no effect on reproductive success (either the presence of a nest, or the average surface area of eggs if a nest was present). Positive covariation in total length, reproductive success, and parasite infection potentially suggest that the influence of parasitic infection on reproductive success may depend upon the strength of selection for larger male body size. In addition, this study provides the first quantitative measurement of ectoparasite infection for both the focal parasite species (Caligus buechlerae) and the host (F. lapillum). Finally, in Chapter 6, I explore how larval survival is mediated by spawning location. In marine reef fish, spatially isolated adult populations may be connected (i.e., have gene flow) via larval dispersal; however, differential larval survival between source populations may mediate both the degree of population connectivity as well as the reproductive success of individuals within those source populations. To evaluate variation in larval quality among different spawning locations, I conducted a laboratory assay to measure the potential effects of source population on larval time to starvation, as starvation is often proposed as a major source of mortality for larval fish. Average survival time was 3.75 days, but survival analysis indicated that starvation resistance did not differ between the two natal sources. For individual nests, mean larval size was negatively correlated with their mean survival time, although this was only apparent in larvae collected from one population (the south coast). My findings indicate that variation in larval traits between source populations does exist, but that on average, source populations had equal resistance to starvation. Given the differences between source populations in (i) the relationship between larval mortality and larval size (i.e., the absence of size effects in one source population) and (ii) overall variation in larval size (larger larvae on the south coast), the relative contribution of larvae from each source population may vary under certain conditions (e.g., low levels of food availability). In conclusion, the field surveys and laboratory experiments conducted in this thesis demonstrate the potential for a variety of factors across multiple life history stages to influence recruitment, growth and reproduction. These findings suggest that factors across multiple life stages (e.g., conspecific density, previous growth histories, or spawning site) have the ability to influence individual success, and in turn populations. By carefully considering and integrating these factors into our studies of population dynamics, we may be able to gain a more comprehensive understanding of the spatio-temporal fluctuations in populations for marine reef fish.</p>

<p>Identifying sources of variation in individual reproductive success is crucial to our understanding of population dynamics and evolutionary ecology. In many systems, the determinants of success are not well known. Where species have parental care, for example, determinants of success can be particularly challenging to partition between parents and offspring. In this thesis I investigate drivers and consequences of variable life histories, for a small reef fish that exhibits male parental care (the common triplefin Forsterygion lapillum). I examined the influence of individual life history, phenotype and behaviour on (1) the performance of recently settled juveniles, and (2) the reproductive success adult males. I made field-based observations of adult males during the breeding season, measured their phenotypic traits (body size and condition) and used their otoliths to reconstruct life history characteristics (hatch dates and mean growth rates). My life history trait reconstructions suggested two alternate pathways to ’success’ for adult males. Successful males hatched earlier and therefore had a developmental ’head start’ over less successful males (i.e., males with eggs > male territory holders without eggs > floaters). Alternatively, males can apparently achieve success by growing faster: for males born in the same month, those with eggs grew faster than those with territories and no eggs, and both groups grew faster than floaters. These results suggest that accelerated growth rate may mediate the effects of a later hatch date, and that both hatch dates and growth rates influence the success of adult males, likely through proximate effects on individual phenotypes. Identifying sources of variation in individual reproductive success is crucial to our understanding of population dynamics and evolutionary ecology. In many systems, the determinants of success are not well known. Where species have parental care, for example, determinants of success can be particularly challenging to partition between parents and offspring. Male parental care is common among fishes, where resources such as high quality territories and mates often may be limiting. In such systems, individual success of offspring may result from distinct life history pathways that are influenced by both parental effects (e.g., timing of reproduction) and by the offspring themselves (e.g., ’personalities’). These pathways, in turn, can induce phenotypic variation and affect success later in life. The drivers and consequences of variable life histories are not well understood in the context of reproductive success. In this thesis I investigate drivers and consequences of variable life histories, for a small reef fish that exhibits male parental care (the common triplefin Forsterygion lapillum). I examined the influence of individual life history, phenotype and behaviour on (1) the performance of recently settled juveniles, and (2) the reproductive success adult males. I made field-based observations of adult males during the breeding season, measured their phenotypic traits (body size and condition) and used their otoliths to reconstruct life history characteristics (hatch dates and mean growth rates). Some males showed no evidence of territorial defence and were defined as ’floaters’; others defended territories, and a subset of these also had nests with eggs present. Adult male body size was significantly higher for males that defended breeding territories, and body condition was significantly higher for the males that had eggs (i.e., had successfully courted females). My otolith-based reconstructions of life history traits suggested two alternate pathways to ’success’ for adult males. Successful males hatched earlier and therefore had a developmental ’head start’ over less successful males (i.e., males with eggs > male territory holders without eggs > floaters). Alternatively, males can apparently achieve success by growing faster: for males born in the same month, those with eggs grew faster than those with territories and no eggs, and both groups grew faster than floaters. These results suggest that accelerated growth rate may mediate the effects of a later hatch date, and that both hatch dates and growth rates influence the success of adult males, likely through proximate effects on individual phenotypes. I evaluated the effects of variable life history in a complimentary lab-based study. Specifically, I manipulated the developmental environments (feeding regime and temperature) for young fish and evaluated the direct effects on life history traits and phenotypes. Then, I conducted an assay to quantify the indirect effects of developmental environment, life history traits, and phenotypes on aggression and performance of young fish. These developmental environments did not have a clear, overall effect on juvenile phenotype or performance (i.e. behavioural aggression and the ability to dominate a resource). Instead, individuals (irrespective of developmental environment) that grew faster and/or longer pelagic larval durations had increased odds of dominating a limited resource. I attributed the non-significant direct effect of developmental environment to within-treatment mortality and variation among individuals in terms of their realised access to food (i.e., dominance hierarchies were apparent in rearing chambers, suggesting a non-uniform access to food). Fish that were more likely to dominate a resource were also more aggressive (i.e., more likely to engage in chasing behaviours). Fish that were larger and more aggressive established territories that were deemed to be of higher ’quality’ (inferred from percent cover of cobble resources). Overall, this study suggests a complex interplay between social systems, phenotype and life history. Developmental environments may influence phenotypes, although behavioural differences among individuals may moderate that effect, contributing to additional variation in phenotypes and life history traits which, in turn, shape the success of individuals. Collectively, my thesis emphasises the consequences of life history variability on success at multiple life stages. These results may be relevant to other species that exhibit male parental care or undergo intense competition for space during early life stages. In addition, my results highlight interactions between life history, phenotype and behaviour that can have important implications for population dynamics and evolutionary ecology.</p>

For many territorial hummingbirds, habitat use is influenced primarily by the interaction between resource acquisition and non-foraging behaviors such as territory advertisement and defense. Previous research has highlighted the importance of foraging-associated habitat features like resource density and distribution in determining the space-use patterns of hummingbirds. Less is known, however, about how habitat selection associated with non-foraging behaviors influences space use by territorial species. We used radio telemetry to examine patterns of territorial space use by Shining Sunbeams (Aglaeactis cupripennis) in high Andean montane forests near Manu National Park, Peru, and Bosque Comunal “El Carmen” near Chordeleg, Ecuador. We quantified within-territory habitat characteristics related to resource acquisition and non-foraging behaviors such as territory advertisement and defense. We found that Shining Sunbeams showed high use of core areas in territories where foraging effort was relatively low. We found no relationship, however, between the position of core areas and habitat characteristics associated with territory defense, predator avoidance, or other non-foraging behaviors. We also found no relationship between use of non-core areas and habitat use based on resource acquisition. Thus, patterns of territorial space use by Shining Sunbeams may be characterized by core areas not determined by foraging behavior. Further studies examining territorial behaviors and the influence of intrusion pressure will help identify the underlying determinants of territory space use by this and other species of Andean hummingbirds. Patrones de uso del espacio territorial por el Colibrí cobrizo (Aglaeactis cupripennis), colibrí montano tropical Para muchos colibríes territoriales, el uso del hábitat está influenciado principalmente por la interacción entre la adquisición de recursos y los comportamientos no forrajeros, como el anuncio y la defensa territorial. Investigaciones previas han resaltado la importancia de las características del hábitat asociadas con el forrajeo, como la densidad y la distribución de los recursos para determinar los patrones de uso del espacio de los colibríes. Sin embargo, se sabe menos acerca de cómo la selección del hábitat asociada con los comportamientos de no alimentación influye en el uso del espacio por parte de las especies territoriales. Utilizamos la radiotelemetría para examinar los patrones de uso del espacio territorial por el Colibrí cobrizo (Aglaeactis cupripennis) en los bosques montañosos altoandinos cerca del Parque Nacional Manu, Perú, y el Bosque Comunal "El Carmen" cerca de Chordeleg, Ecuador. Cuantificamos las características del hábitat dentro del territorio relacionadas con la adquisición de recursos y los comportamientos no forrajeros, como el anuncio y defensa territorial. Descubrimos que el Colibrí cobrizo mostraba un alto uso de áreas centrales en territorios donde el esfuerzo de búsqueda de alimento era relativamente bajo. Sin embargo, no encontramos relación entre la posición de las áreas centrales y las características del hábitat asociadas con la defensa del territorio, la evitación de depredadores u otros comportamientos que no son de forrajeo. Tampoco encontramos relación entre el uso de áreas no centrales y el uso del hábitat basado en la adquisición de recursos. Por lo tanto, los patrones de uso del espacio territorial por el Colibrí cobrizo puede caracterizarse por áreas centrales no determinadas por el comportamiento de búsqueda de alimento. Otros estudios que examinen los comportamientos territoriales y la influencia de la presión de intrusión ayudarán a identificar los determinantes subyacentes del uso del espacio territorial por esta y otras especies de colibríes andinos. Table S1. Summary of kernel density estimated areas, parameters, and the position of the core area for hummingbird territories 1-19. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

<p>Identifying sources of individual variation in reproductive success has been a longstanding challenge for evolutionary ecologists. Reproductive success among individuals can be due to several factors such as competition between conspecifics for nest sites and mating partners, mate choice, or by the physical environment. Reproductive success, particularly among males, can be extremely diverse both within and between species and determining which components contribute to success can be particularly challenging. In this thesis, I investigated patterns and drivers of reproductive success in a temperate marine reef fish, Forsterygion lapillum (the common triplefin). Specifically, I examined how male quality, nest quality, and female choice influence male reproductive success. Additionally, I quantified male reproductive success during the winter and summer of the breeding season to examine the temporal dynamics of breeding success in F. lapillum. Selection of mates by females can be driven by the quality and behavioural attributes of the male or by the quality of resources offered. In Chapter 2, using field-based observations, combined with a lab-based study, I evaluated the effects of different male traits and nest characteristics on female choice and male reproductive success. Specifically, I observed egg guarding males in the field during the breeding season and recorded their phenotypic traits, behaviours, and nest characteristics. I then examined their influence on 3 different components of male reproductive success (brood size, individual egg size, and mate attraction). Additionally, I conducted dichotomous choice tests in the laboratory to evaluate female preference for different sized males, holding different sized nests. In the field, I did not detect a significant relationship between male mating success and male total length or nest size. Brood size and individual egg size were highly variable among sampled males, however, further factors such as courtship frequency, and the number of interactions with potential predators did not explain any additional variation. The number of agonistic displays performed by egg guarding males was the only factor to influence egg size, however, it had no direct impact on brood size or mate attraction. On the contrary, results from the laboratory experiment suggested that male total length and nest size were important during female choice. Females were attracted to and spawned more frequently with larger males holding larger nests. Additionally, females showed a particular preference towards males that displayed intense courtship behaviours. These results suggest that variation in reproductive success among individuals is not random in the common triplefin (F. lapillum) and may be due to a range of complex factors. In natural systems, individual variation in mating success is known to be highly dynamic and vary over time. In Chapter 3, I addressed 3 questions related to reproductive success in male common triplefin: 1) Does the operational sex ratio (OSR) and the density of individuals change predictably within the breeding season? 2) Does male reproductive success change within the breeding season? And 3) Does the age and growth rate of successful males change within the breeding season? To address these questions, I sampled a population of F. lapillum during two periods of the breeding season and quantified a set of morphological and physical traits. Furthermore, I reconstructed individual life histories from the otoliths of egg guarding males. My results show that the density of individuals in the population increased during the summer months, but the operational sex ratio (OSR) remained male-biased. Male reproductive success in terms of brood size and average egg size did not fluctuate during the sampling period. However, the size of males and the size of the nest (cobblestone) held by males was significantly larger in summer compared to winter. Interestingly, successful males sampled in the winter had hatched significantly earlier than successful males sampled in the summer, but their average growth rate remained similar. These findings indicate that variation in male traits across the breeding season plays an important role in female mate choice. The mating system and pool of mating individuals in the common triplefin (F. lapillum) is highly dynamic over the year and has the potential to shape the success of individuals. Overall, this study emphasizes the importance of considering multiple cues and temporal dynamics when disentangling the determinants of individual reproductive success. These findings suggest that male-male competition and female mate choice have a significant influence on male reproductive success. The reproductive ecology of F. lapillum is highly complex and my research has provided valuable insight into its dynamic nature. These results may apply to other species with male parental care and provides an important contribution towards understanding sexual selection and the evolution of mating systems with male parental care.</p>

<p>Identifying sources of individual variation in reproductive success has been a longstanding challenge for evolutionary ecologists. Reproductive success among individuals can be due to several factors such as competition between conspecifics for nest sites and mating partners, mate choice, or by the physical environment. Reproductive success, particularly among males, can be extremely diverse both within and between species and determining which components contribute to success can be particularly challenging. In this thesis, I investigated patterns and drivers of reproductive success in a temperate marine reef fish, Forsterygion lapillum (the common triplefin). Specifically, I examined how male quality, nest quality, and female choice influence male reproductive success. Additionally, I quantified male reproductive success during the winter and summer of the breeding season to examine the temporal dynamics of breeding success in F. lapillum. Selection of mates by females can be driven by the quality and behavioural attributes of the male or by the quality of resources offered. In Chapter 2, using field-based observations, combined with a lab-based study, I evaluated the effects of different male traits and nest characteristics on female choice and male reproductive success. Specifically, I observed egg guarding males in the field during the breeding season and recorded their phenotypic traits, behaviours, and nest characteristics. I then examined their influence on 3 different components of male reproductive success (brood size, individual egg size, and mate attraction). Additionally, I conducted dichotomous choice tests in the laboratory to evaluate female preference for different sized males, holding different sized nests. In the field, I did not detect a significant relationship between male mating success and male total length or nest size. Brood size and individual egg size were highly variable among sampled males, however, further factors such as courtship frequency, and the number of interactions with potential predators did not explain any additional variation. The number of agonistic displays performed by egg guarding males was the only factor to influence egg size, however, it had no direct impact on brood size or mate attraction. On the contrary, results from the laboratory experiment suggested that male total length and nest size were important during female choice. Females were attracted to and spawned more frequently with larger males holding larger nests. Additionally, females showed a particular preference towards males that displayed intense courtship behaviours. These results suggest that variation in reproductive success among individuals is not random in the common triplefin (F. lapillum) and may be due to a range of complex factors. In natural systems, individual variation in mating success is known to be highly dynamic and vary over time. In Chapter 3, I addressed 3 questions related to reproductive success in male common triplefin: 1) Does the operational sex ratio (OSR) and the density of individuals change predictably within the breeding season? 2) Does male reproductive success change within the breeding season? And 3) Does the age and growth rate of successful males change within the breeding season? To address these questions, I sampled a population of F. lapillum during two periods of the breeding season and quantified a set of morphological and physical traits. Furthermore, I reconstructed individual life histories from the otoliths of egg guarding males. My results show that the density of individuals in the population increased during the summer months, but the operational sex ratio (OSR) remained male-biased. Male reproductive success in terms of brood size and average egg size did not fluctuate during the sampling period. However, the size of males and the size of the nest (cobblestone) held by males was significantly larger in summer compared to winter. Interestingly, successful males sampled in the winter had hatched significantly earlier than successful males sampled in the summer, but their average growth rate remained similar. These findings indicate that variation in male traits across the breeding season plays an important role in female mate choice. The mating system and pool of mating individuals in the common triplefin (F. lapillum) is highly dynamic over the year and has the potential to shape the success of individuals. Overall, this study emphasizes the importance of considering multiple cues and temporal dynamics when disentangling the determinants of individual reproductive success. These findings suggest that male-male competition and female mate choice have a significant influence on male reproductive success. The reproductive ecology of F. lapillum is highly complex and my research has provided valuable insight into its dynamic nature. These results may apply to other species with male parental care and provides an important contribution towards understanding sexual selection and the evolution of mating systems with male parental care.</p>

K.L.M. Martin, M.A. Chotkowski, and M.H. Horn, Introduction. R.N. Gibson, Methods for Studying Intertidal Fishes. C.D. Zander, J. Nieder, and K.L.M. Martin, Vertical Distribution Patterns. K.L.M. Martin and C.R. Bridges, Respiration in Air and Water. D.H. Evans, J.B. Claiborne, and G.A. Kormanik, Osmoregulation, Acid-Base Regulation, and Nitrogen Excretion. R.N. Gibson, Movement and Homing in Intertidal Fishes. K. Kotrschal, Sensory Systems. E.E. DeMartini, Intertidal Spawning. R.M. Coleman, Parental Care in Intertidal Fishes. C.A. Pfister, Recruitment of Intertidal Fishes. M.H. Horn and F.P. Ojeda, Herbivory. S.F. Norton and A.E. Cook, Predation by Fishes in the Intertidal. R.N. Gibson and R.M. Yoshiyama, Intertidal Fish Communities. M.A. Chotkowski, D. G. Buth and K. Prochazka, Systematics of Intertidal Fishes. K. Prochazka, M. A. Chotkowski and D. B. Buth, Biogeography of Intertidal Fishes. M. H. Horn, Convergent Evolution and Community Convergence: Research Potential Using Intertidal Fishes. H.P. Schultze, The Fossil Record of the Intertidal Zone. Subject Index.

Oxygen is essential for most eukaryotic lifeforms, as it supports mitochondrial oxidative phosphorylation to supply ∼90% of cellular adenosine triphosphate (ATP). Fluctuations in O2 present a major stressor, with hypoxia leading to a cascade of detrimental physiological changes that alter cell operations and ultimately induce death. Nonetheless, some species episodically tolerate near-anoxic environments, and have evolved mechanisms to sustain function even during extended hypoxic periods. While mitochondria are pivotal in central metabolism, their role in hypoxia tolerance remains ill defined. Given the vulnerability of the brain to hypoxia, mitochondrial function was tested in brain homogenates of three closely related triplefin species with varying degrees of hypoxia tolerance (Bellapiscis medius, Forsterygion lapillum and Forsterygion varium). High-resolution respirometry coupled with fluorometric measurements of mitochondrial membrane potential (mtMP) permitted assessment of differences in mitochondrial function and integrity in response to intermittent hypoxia and anoxia. Traditional steady-state measures of respiratory flux and mtMP showed no differences among species. However, in the transition into anoxia, the tolerant species B. medius and F. lapillum maintained mtMP at O2 pressures 7- and 4.4-fold lower, respectively, than that of the hypoxia-sensitive F. varium and exhibited slower rates of membrane depolarisation. The results indicate that dynamic oxic-hypoxic mitochondria transitions underlie hypoxia tolerance in these intertidal fish.

Life between tides: Spatial and temporal variations of an intertidal macroalgal community at Potter Peninsula, South Shetland Islands, Antarctica

Endogenous cycles, activity patterns and energy expenditure of an intertidal fish is modified by artificial light pollution at night (ALAN)

Boldness-mediated habitat use tactics and reproductive success in a wild large herbivore

This paper presents a comparative analysis of territoriality in three intertidal (Lipophrys pholis, Coryphoblennius galerita, Salaria pavo) and two subtidal (Tripterygion delaisi, Parablennius pilicornis) blennioid fishes. Focal-animal observations of males guarding eggs showed that: (i) intertidal species had smaller territories that were less frequently patrolled; (ii) in subtidal species feeding was limited to the territory, while in intertidal fishes a substantial proportion of the feeding acts occurred outside the defended area; (iii) intertidal species spent less time out of the nest and showed a lower level of locomotory activity; (iv) subtidal species were subjected to a higher number of territorial intrusions with more species intruding their territory, some of them potential egg predators; (v) subtidal species performed several water column displays that played a significant role in courtship, while in intertidal fishes these displays are almost absent. Signalling without the presence of a female was almost absent in intertidal species. It is argued that intertidal fishes minimize the time spent out of the nest and the loss of contact with the substrate, features that may be of high survival value in conditions of strong turbulence. Although intertidal species have a reduced time available for feeding, this may be compensated by lower levels of locomotory activity, territorial defense and risk of egg predation.

Biological and physical factors interact to determine habitat use by animals. While sessile organisms inhabiting intertidal areas have been well studied, the processes underlying the use of intertidal areas by highly mobile animals such as fishes remain poorly understood. This study examines whether an intertidal fish, the mummichog Fundulus heteroclitus, preferentially uses habitats where growth rate is maximized or, like most sessile animals, is restricted to habitats providing escape from strong negative biological interactions but compromising growth. I compared growth rates and predation rates on adult F. heteroclitus at 3 Rhode Island salt marshes in 2 seasons (summer and fall). Salt marshes varied in the types of habitat (creek, pond, channel, mudflat) available to fishes within each marsh. Growth rates of marked mummichogs held in cages were determined in each habitat and each marsh for 6 wk. Predation risk was assessed by determining mortality of F. heteroclitus tethered in each habitat in each of the 2 seasons. Habitat use was quantified by trapping fish in each habitat in each season. Both growth rate and predation risk influenced habitat use by F. heteroclitus in these intertidal salt marshes. Overall, salt marshes offered opportunities for both higher growth rates and shelter from predation compared to areas outside salt marshes. However, mummichogs often faced trade-offs between predation refuge and growth in specific habitat types. When predation risk was high across all habitat types in a marsh, habitats associated with the highest growth rates were used. If a predation refuge was available, habitat use increased, even when growth rates in the habitat were low. A habitat characterized by both shelter and high growth rates, e.g. Coggeshall Cove ponds in fall, were used almost exclusively. Variation in quality of the same habitat type in different marshes led to differences in overall marsh quality. Determination of profitability of habitat for fishes cannot be assessed through habitat use alone; measurement of factors, such as predation risk and growth, which influence habitat quality are also necessary.

Fluctuating asymmetry, the non-directional deviation from bilateral symmetry resulting from developmental instability, can indicate early-life environmental stress. While fluctuating asymmetry can affect individual survival and reproductive success, its effect on fitness differs between species. Here, we analyzed up to 27 years of mark-recapture data from 894 RFID tagged individuals of three forest-living bat species in southern Germany to investigate the degree of fluctuating asymmetry in forearm length. In Bechstein’s bats, Myotis bechsteinii, the species with the highest sample size, we furthermore investigated if fluctuating asymmetry has become more frequent over the study period, a time when juvenile bats have grown larger forearms in response to warmer summers. We also investigated whether fluctuating asymmetry affects individual lifespan and lifetime reproductive success in female Myotis bechsteinii. The degree of fluctuating asymmetry clearly exceeding the measurement error estimated on recaptured individuals was similar in all three species (1.8%). In female Myotis bechsteinii, the frequency of fluctuating asymmetry did not increase over the course of the study and even strong asymmetry had no effect on individual reproductive success and life expectancy. Our data suggest that fluctuating asymmetry is a poor predictor of fitness in the female Myotis bechsteinii studied, and is so far unaffected by the warming environment which is leading to larger individuals in our study population.

Female ungulate reproductive success is dependent on the survival of their young, and affected by maternal resource selection, predator avoidance, and nutritional condition. However, potential hierarchical effects of these factors on reproductive success are largely unknown, especially in multi-predator landscapes. We expanded on previous research of neonatal white-tailed deer (Odocoileus virginianus) daily survival within home ranges to assess if resource use, integrated risk of 4 mammalian predators, maternal nutrition, winter severity, hiding cover, or interactions among these variables best explained landscape scale variation in daily or seasonal survival during the post-partum period. We hypothesized that reproductive success would be limited greater by predation risk at coarser spatiotemporal scales, but habitat use at finer scales. An additive model of daily non-ideal resource use and maternal nutrition explained the most (69%) variation in survival; though 65% of this variation was related to maternal nutrition. Strong support of maternal nutrition across spatiotemporal scales did not fully support our hypothesis, but suggested reproductive success was related to dam behaviors directed at increasing nutritional condition. These behaviors were especially important following severe winters, when dams produced smaller fawns with less probability of survival. To increase nutritional condition and decrease wolf (Canis lupus) predation risk, dams appeared to place fawns in isolated deciduous forest patches near roads. However, this resource selection represented non-ideal resources for fawns, which had greater predation risk that led to additive mortalities beyond those related to resources alone. Although the reproductive strategy of dams resulted in greater predation of fawns from alternative predators, it likely improved the life-long reproductive success of dams, as many were late-aged (>10 years old) and could have produced multiple litters of fawns. Our study emphasizes understanding the scale-dependent hierarchy of factors limiting reproductive success is essential to providing reliable knowledge for ungulate management.

Resilience of a rocky intertidal fish community in a physically unstable environment