Mary A. Sewell

Contributing to marine pollution by washing your face: Microplastics in facial cleansers

Plastics pollution in the ocean is an area of growing concern, with research efforts focusing on both the macroplastic (>5mm) and microplastic (<5mm) fractions. In the 1990 s it was recognized that a minor source of microplastic pollution was derived from liquid hand-cleansers that would have been rarely used by the average consumer. In 2009, however, the average consumer is likely to be using microplastic-containing products on a daily basis, as the majority of facial cleansers now contain polyethylene microplastics which are not captured by wastewater plants and will enter the oceans. Four microplastic-containing facial cleansers available in New Zealand supermarkets were used to quantify the size of the polythelene fragments. Three-quarters of the brands had a modal size of <100 microns and could be immediately ingested by planktonic organisms at the base of the food chain. Over time the microplastics will be subject to UV-degradation and absorb hydrophobic materials such as PCBs, making them smaller and more toxic in the long-term. Marine scientists need to educate the public to the dangers of using products that pose an immediate and long-term threat to the health of the oceans and the food we eat.

Can we predict ectotherm responses to climate change using thermal performance curves and body temperatures

Thermal performance curves (TPCs), which quantify how an ectotherms body temperature (Tb ) affects its performance or fitness, are often used in an attempt to predict organismal responses to climate change. Here, we examine the key - but often biologically unreasonable - assumptions underlying this approach; for example, that physiology and thermal regimes are invariant over ontogeny, space and time, and also that TPCs are independent of previously experienced Tb. We show how a critical consideration of these assumptions can lead to biologically useful hypotheses and experimental designs. For example, rather than assuming that TPCs are fixed during ontogeny, one can measure TPCs for each major life stage and incorporate these into stage-specific ecological models to reveal the life stage most likely to be vulnerable to climate change. Our overall goal is to explicitly examine the assumptions underlying the integration of TPCs with Tb , to develop a framework within which empiricists can place their work within these limitations, and to facilitate the application of thermal physiology to understanding the biological implications of climate change.

Temperature limits to fertilization and early development in the tropical sea urchin Echinometra lucunter

Abstract Temperature limits for fertilization and early development were examined in the tropical sea urchin Echinometra lucunter to test the hypothesis that the temperature range for normal development limits the geographical distribution of marine species (Andronikov, V.B., 1975. Heat resistance of gametes of marine invertebrates in relation to temperature conditions under which the species exist. Mar. Biol. 30, 1–12). Eggs could be fertilized from 12 to 37°C, with high fertilization at temperatures above 15°C. Development to echinoplutei occurred at 16, 18 and 23°C, but appeared to be optimal at temperatures from 27–34°C. Hatched embryos (blastulae, gastrulae) and echinoplutei larvae could survive temperatures between 38 and 40°C for 2 h, which might be important for larvae that are carried into the shallow, heated waters of the Caribbean reef flat. Examination of the seawater temperatures at the northern and southern geographical limits (Beaufort, North Carolina; Florianopolis, Brazil) showed winter monthly minimum temperature of 18°C and summer monthly maximum of 27.5 and 25.5°C, respectively. Fertilization and normal development can occur at temperatures outside those seen in natural conditions in any part of the geographical range. Thus, the geographical distribution of Echinometra lucunter does not appear to be limited by the temperatures at which normal development occurs, in refutation of Andronikovs hypothesis. The distribution of E. lucunter may instead be limited by factors such as adult temperature tolerances, temperatures needed for growth or spawning, or hydrographic features that limit larval settlement and juvenile survival.

Simultaneous Spawning of Six Species of Echinoderms in Barkley Sound, British Columbia

A clip for aiding the attachment of plasterboard to structural columns and the like comprising a box section having a spring flap formed integrally therewith. The spring flap slips onto a flange of the column and the box section provides attaching surfaces for sheet metal screws. When several clips are used the column may be encapsulated and therefore fireproofed by the plasterboard.

Aspects of the ecology of Stichopus mollis (Echinodermata : Holothuroidea) in north-eastern New Zealand

Abstract The size‐frequency distribution, sex ratio, and visceral index in a population of the aspidochirote holothurian Stichopus mollis (Hutton, 1872) were studied on the north‐east coast of New Zealand. Adult Stichopus mollis ranged in length from 13 to 25 cm, and showed a unimodal size‐frequency distribution. Young S. mollis were rare, and were found under boulders in the shallow subtidal zone (5–8 m). The population of S. mollis under study showed a 1 : 1 sex ratio; three hermaphrodites were found. The viscera index maintained an approximately uniform value throughout the reproductive season. No evidence was found for spontaneous evisceration or seasonal atrophy of the viscera. Two predatory attacks on S. mollis by the asteroid Luidia varia were observed.

Mice Lacking the Neuropeptide α-Calcitonin Gene-Related Peptide Are Protected Against Diet-Induced Obesity

Alpha-calcitonin gene-related peptide (alphaCGRP) is a neuropeptide that is expressed in motor and sensory neurons. It is a powerful vasodilator and has been implicated in diverse metabolic roles. However, its precise physiological function remains unclear. In this study, we investigated the role of alphaCGRP in lipid metabolism by chronically challenging alphaCGRP-specific knockout (alphaCGRP(-/-)) and control mice with high-fat diet regimens. At the start of the study, both animal groups displayed similar body weights, serum lipid markers, and insulin sensitivity. However, alphaCGRP(-/-) mice displayed higher core temperatures, increased energy expenditures, and a relative daytime (nonactive) depression in respiratory quotients, which indicated increased beta-oxidation. In response to fat feeding, alphaCGRP(-/-) mice were comparatively protected against diet-induced obesity with an attenuated body weight gain and an overall reduction in adiposity across all the three diets examined. AlphaCGRP(-/-) mice also displayed improved glucose handling and insulin sensitivity, lower im and hepatic lipid accumulation, and improved overall metabolic health. These findings define a new role for alphaCGRP as a mediator of energy metabolism and opens up therapeutic opportunities to target CGRP action in obesity.

Variability in the reproductive cycle of Stichopus mollis (Echinodermata: Holothuroidea)

Summary The reproductive cycle of the temperate aspidochirote holothurian Stichopus mollis (Hutton, 1872) was examined on the north-east coast of New Zealand from October 1985 through April 1987. Stichopus mollis exhibits an annual reproductive cycle similar to that described for temperate Northern Hemisphere aspidochirotes. Synchronous gonad development is observed in both males and females, with the gonads reaching a maximum size during the austral summer. Although the reproductive peak occurred in the summers of 1986 and 1987, the duration of the reproductive season and the timing of spawning differed between years. In 1987 the gonad index maintained a high value for a 4 month period, with spawning 2–3 months later than in the 1986 season. The extended reproductive season in 1987 may have resulted from the presence of low sea water temperatures associated with an El Nino.

Rapid adaptation to food availability by a dopamine-mediated morphogenetic response

Food can act as a powerful stimulus, eliciting metabolic, behavioral and developmental responses. These phenotypic changes can alter ecological and evolutionary processes; yet, the molecular mechanisms underlying many plastic phenotypic responses remain unknown. Here we show that dopamine signaling through a type-D2 receptor mediates developmental plasticity by regulating arm length in pre-feeding sea urchin larvae in response to food availability. While prey-induced traits are often thought to improve food acquisition, the mechanism underlying this plastic response acts to reduce feeding structure size and subsequent feeding rate. Consequently, the developmental program and/or maternal provisioning predetermine the maximum possible feeding rate, and food-induced dopamine signaling reduces food acquisition potential during periods of abundant resources to preserve maternal energetic reserves. Sea urchin larvae may have co-opted the widespread use of food-induced dopamine signaling from behavioral responses to instead alter their development.

Reproduction of the temperate aspidochirote Stichopus mollis (Echinodermata : Holothuroidea) in New Zealand

Abstract Reproduction of the holothurian Stichopus mollis from the north-east coast of New Zealand was investigated through histological examination of the gonads. Changes in the gametogenic condition of the gonads are documented by the maturity index and oocyte size-frequency methods. The ovary or testis is located in the anterior coelom, and consists of two bilaterally symmetrical tufts of gonad tubules. S. mollis has an annual reproductive cycle, spawning in the austral summer. Males and females show synchronous development. Growth of the gonads begins in early spring, and involves the regrowth of the gonad basis, with subsequent branching and lengthening of the gonad tubules. In female sea cucumbers, oocytes develop from 5 µm to a maximum of 180 µm. Growth is characterised by the formation of larger oocytes surrounded by folJicular epithelium in the centre of the tubules, with a ring of smaller oocytes along the tubule wall. The testis retains a large spermatocyte layer throughout most of gonad growth...

Growth Attenuation with Developmental Schedule Progression in Embryos and Early Larvae of Sterechinus neumayeri Raised under Elevated CO2

The Southern Ocean, a region that will be an ocean acidification hotspot in the near future, is home to a uniquely adapted fauna that includes a diversity of lightly-calcified invertebrates. We exposed the larvae of the echinoid Sterechinus neumayeri to environmental levels of CO2 in McMurdo Sound (control: 410 µatm, Ω = 1.35) and mildly elevated pCO2 levels, both near the level of the aragonite saturation horizon (510 µatm pCO2, Ω = 1.12), and to under-saturating conditions (730 µatm, Ω = 0.82). Early embryological development was normal under these conditions with the exception of the hatching process, which was slightly delayed. Appearance of the initial calcium carbonate (CaCO3) spicule nuclei among the primary mesenchyme cells of the gastrulae was synchronous between control and elevated pCO2 treatments. However, by prism (7 days after the initial appearance of the spicule nucleus), elongating arm rod spicules were already significantly shorter in the highest CO2 treatment. Unfed larvae in the 730 µatm pCO2 treatment remained significantly smaller than unfed control larvae at days 15–30, and larvae in the 510 µatm treatment were significantly smaller at day 20. At day 30, the arm lengths were more differentiated between 730 µatm and control CO2 treatments than were body lengths as components of total length. Arm length is the most plastic morphological aspect of the echinopluteus, and appears to exhibit the greatest response to high pCO2/low pH/low carbonate, even in the absence of food. Thus, while the effects of elevated pCO2 representative of near future climate scenarios are proportionally minor on these early developmental stages, the longer term effects on these long-lived invertebrates is still unknown.