No abstract

Palatable (Batesian) mimics of unprofitable models could use behavioral mimicry to compensate for the ease with which they can be visually discriminated, or to augment an already close morphological resemblance. We evaluated these contrasting predictions by assaying the behavior of 57 field-caught species of mimetic hover flies (Diptera: Syrphidae), and quantifying their morphological similarity to a range of potential hymenopteran models. A purpose-built phylogeny for the hover flies was used to control for potential lack of independence due to shared evolutionary history. Those hover fly species that engage in behavioral mimicry (mock stinging, leg waving, wing wagging) were all large wasp mimics within the genera Spilomyia and Temnostoma. While the behavioral mimics assayed were good morphological mimics, not all good mimics were behavioral mimics. Therefore, while the behaviors may have evolved to augment good morphological mimicry, they have not been selected in all hover fly species.

Deep-sea nudibranchs (Mollusca: Gastropoda: Heterobranchia) have rarely been reported from eastern Canada. Here we describe range extensions for two species found in the northwest Atlantic Ocean. Tritonia newfoundlandica Valdés, Murillo, McCarthy & Yedinak, 2017 was originally collected on the Flemish Cap off Newfoundland, Canada, and Doridoxa ingolfiana Bergh, 1899 was originally found off western Greenland with further records in Iceland, northern Norway, and southeastern Canada. We extend the northern range of T. newfoundlandica 1067 km along the eastern coast of North America and add occurrences of D. ingolfiana in the Labrador Sea, bridging a 2044 km gap between previous records in Greenland and southern Newfoundland. The latter species thus exhibits a continuous distribution from Svalbard, the Faroe Islands, Greenland, down to the southern tip of the Grand Banks in eastern Canada. Tritonia newfoundlandica was collected in its known depth range, whereas the depth distribution of D. ingolfiana was extended by 30 m to a maximum depth of 1375 m. Both species were collected with numerous nephtheid corals, suggesting that there may be a functional relationship, where the nudibranchs find refuge or food on them.

The earthquake of 3 June 1956 on the Arctic margin of Canada, north­west of Borden Island, has been briefly studied during a reappraisal of instru­mental data of some Canadian earthquakes. The revised parameters are: lat­itude 79.83°N±0.20°, longitude 116.99°W±l.0°, crustal depth (18±18 km), H = 05h 19m 26.6s U.T., and magnitude mb 5.7, Ms 5.4. The epicentre is unlikely to be more accurate than ±20 km. This is the second largest earthquake known from the Arctic margin of Canada.

Banded killifish (Fundulus diaphanus) are a small, freshwater fish that have a wide distribution in eastern North America and are considered a species-at-risk on the island of Newfoundland. We posit that because Newfoundland's summer climate is much cooler than other locations at similar latitudes, there may be different constraints on banded killifish reproduction. We measured embryonic development under four temperatures (10, 16, 22, and 28 C) and two conductivities (0.6 and 1.2 mS/cm). Warmer temperatures led to more developed embryos prior to death in embryos that ultimately did not hatch, higher hatch success, faster hatch time, and fewer thermal units to hatch. Conductivity and temperature interacted to affect hatch size. Therefore, banded killifish are likely challenged by the low temperature and conductivity conditions in Newfoundland which may result in reproductive constraints, and perhaps complete cohort failures in relatively cool summers.

This paper presents the first records of the brittle star Ophiactis abyssicola in Canadian waters and range extensions of up to 1900 km in the Northwest Atlantic from previously known locations. Samples were collected off northern Labrador and the northern portion of insular Newfoundland (eastern Canada) at 433 and 1097 m depths, respectively. This newly recorded species of brittle star from the bathyal zone off Newfoundland and Labrador adds to the marine biodiversity of Canada and to the general distribution knowledge of O. abyssicola.

Initial body size can indicate quality within‐species, with large size increasing the likelihood of survival. However, some populations or individuals may have body size disadvantages due to spatial/temporal differences in temperature, photoperiod, or food. Across‐populations, animals often have locally adapted physiology to compensate for relatively poor environmental influences on development and growth, while within‐population individual behavioral adjustments can increase food intake after periods of deprivation and provide opportunities to catch up (growth compensation). Previous work has shown that growth compensation should include within‐population differences related to short growing seasons due to delayed hatch time. We tested the hypothesis that individual fish that hatch later grow faster than those that hatch earlier. The relative magnitude of such a response was compared with growth variation among populations. We sampled young of the year Arctic charr and brook trout from five rivers in northern Labrador. Daily increments from otoliths were used to back‐calculate size to a common age and calculate growth rates. Supporting the hypothesis, older fish were not larger at capture than younger fish because animals that hatched later grew faster, which may indicate age‐based growth compensation.

Initial body size can indicate quality within-species, with large size increasing the likelihood of survival. However, some populations or individuals may have body size disadvantages due to spatial/temporal differences in temperature, photoperiod, or food availability. Across-populations animals often have locally adapted physiology to compensate for poor environmental influences on development and growth, while within-populations behavioural adjustments that increase food intake after periods of deprivation provide opportunities to catch up (growth compensation). We posit a theoretical extension of growth compensation to include within-population differences related to short growing seasons due to delayed hatch time. We tested the hypothesis that individual fish that hatch later grow faster than those that hatch earlier. The relative magnitude of such a response was compared to growth variation among populations and between related species. We sampled young of the year Arctic charr and brook trout from five rivers in northern Labrador. Daily increments from otoliths were used to back-calculate size to a common age and calculate growth rates. Supporting the hypothesis, older fish were not larger at capture than younger fish, because animals that hatched later grew faster which may indicate age-based growth compensation.