Dr. Lauren Chapman, McGill University
Hot Fish in a Warming World: Effects of Dual Stressors on Energetics and Performance of African Equatorial Fishes
Tropical fishes may be more sensitive to climate warming than temperate species because they experience small annual temperature fluctuations and seem to live relatively close to their maximum thermal tolerance. Here, I present results of a series of acclimation and rearing experiments that explore effects of temperature on energetics, behavior, and performance (e.g. aerobic scope, swim performance) of two East African fishes: the Egyptian mouth-brooder (Pseudocrenilabrus multicolor) and the Nile perch (Lates niloticus). Our results demonstrate that aerobic performance can be maximal at temperatures near the limit of ecological relevance, and for Nile perch, longer exposure time results in higher thermal tolerance and a decrease in metabolic costs of elevated temperature. In addition to direct effects of thermal stress on fish performance, climate warming is likely to interact with other stressors, in particular, aquatic hypoxia, because oxygen solubility decreases with rising temperature while ectothermic metabolism increases. To explore the interaction between hypoxia and temperature, F1 offspring of P. multicolor were reared in four treatments (low or high oxygen; cool or hot temperature). We observed developmental plasticity in morphological traits (e.g., gill size), behaviour, energetics, and performance; and development under hypoxia modulated negative effects of acute thermal stress on swim performance.
Dr. Jeff Hutchings, Dalhousie University
Adaptive significance of life-history variability in landlocked Atlantic salmon
Population viability depends on life histories that generate consistently positive rates of per capita growth (r > 0). For many Atlantic salmon, the fitness benefits of anadromy (large size: 45-120cm; rapid growth: 30-40cm yr-1; high fecundity: 103 eggs) exceed the primary cost (high mortality: ~95% yr-1). In some systems (Newfoundland), the fitness of non-anadromous, or ‘landlocked’, salmon (males and females) equals that of sea-run salmon, resulting in their co-existence. Where migration to and from sea is prevented, landlocked salmon tend to exhibit one of two life-history types. Large landlocked salmon (>35-50cm) are associated with large lakes that sustain abundant small fish, e.g., smelt or vendace; they are able to co-exist with multiple species at multiple trophic levels. By contrast, small landlocked salmon mature at small sizes (<15-20cm), produce few eggs, and live brief lives. Their life history seems possible only in waters of low fish species diversity and (likely) no predators. Recovery of depleted landlocked populations are likely inhibited by Allee effects and, in some cases, low r. Using optimality modelling, I hope to identify the life-history boundary conditions that constrain population viability and serve to limit the distribution of landlocked Atlantic salmon throughout its native range.
Dr. Alison Bell, University of Illinois, Urbana-Champaign
Transgenerational and behavioral plasticity at the molecular level in sticklebacks
In this talk I will present two case studies of behavioral plasticity at the molecular level in threespined sticklebacks, a species famous for their behavioral repertoire. In the first case study, I will show that transgenerational and developmental plasticity in response to cues of predation risk produce comparable and nonadditive responses at the phenotypic and molecular level. For example, offspring with both personally-acquired and paternally-acquired cues of predation risk resembled offspring that received cues from a single source. A similar pattern was detected at the molecular level: there was a core set of genes that were differentially expressed in the brains of offspring, regardless of whether risk was experienced by their father, themselves or both. This transcriptional response is consistent with a molecular switch that is activated in response to an environmental cue, regardless of whether the environment is experienced by parents, their offspring or both. The second half of the talk will focus on short-term behavioral plasticity in response to social interactions. I will present results showing rapid and dramatic epigenomic plasticity in response to a brief territorial challenge in male sticklebacks. I will show how we are integrating time course brain gene expression data with a transcriptional regulatory network, and linking changes in gene expression to changes in chromatin accessibility. Together, these two case studies illustrate how examining behavioral plasticity at the molecular level provides insights into the proximate causes and evolution of behavior.
Dr. Sigal Balshine, McMaster University
Understanding Cannibalism, Competition, and Care: lessons from a singing toadfish
Cannibalism of young is a common, yet seemingly paradoxical, phenomenon observed across a wide variety of taxa. Behavioural ecologists have been particularly interested in understanding this behaviour within the context of parental care, because of the high putative costs of terminating offspring that have already received investment. Using a series of field and lab experiments with the plainfin midshipman fish (Porichthys notatus), my students and I have investigated why offspring cannibalism occurs. We show that plainfin midshipman males endure an extremely long (3 - 4 months) and taxing parental care period, but that (surprisingly) males with the lowest energy reserves are least likely to engage in offspring cannibalism. The highest rates of offspring cannibalism are associated with low nest paternity and periods of intense male-male competition. The plainfin midshipman has many unusual courtship behaviours and parental care tactics, including using sound to win over females. Competition is rife, with many males taking over nests from other males and many sneaker males in the population who steal fertilizations from caring males. I will describe our recent research progress on studying competition, cannibalism and care in this fascinating singing toadfish. I will also highlight how fish behaviour can be linked to population dynamics, and foodweb dynamics.
As part of EEEF2018, there will be a symposium dedicated to Atlantic salmon conservation and restoration, with a special emphasis on landlocked populations.The body of literature on Atlantic salmon biology is immense. However, relatively little is known about landlocked salmon throughout the species range. Many remaining populations of landlocked salmon are in severe decline and the focus of extensive, ongoing monitoring or reintroduction efforts (e.g. Lake Vänern, Lake Ontario, Lake Champlain). In this light, the goals of the EEEF symposium will be to (i) bring together world experts on the biology of landlocked salmon to update what is known of the ecology, evolution, genetics and behavior of these unique populations, and (ii) complement this focus with talks from leaders in the conservation and recovery of anadromous populations. By doing so, the symposium provides an excellent opportunity for the exchange of ideas and experiences which we hope will ultimately help in the effective management and protection of unique and threatened populations of Atlantic salmon.
If you are interested in giving an oral presentation or poster associated with the Atlantic salmon symposium, please contact Dylan Fraser (email@example.com).
A male landlocked Atlantic salmon from the Boquet River, a tributary of Lake Champlain, New York, U.S.A. Photo credit: Dylan Fraser
Releasing a landlocked Atlantic salmon following transport above a barrier dam on the Boquet River, New York, U.S.A. Photo credit: Dylan Fraser