Ecosystem engineers such as the Antarctic scallop (Adamussium colbecki) shape marine communities. Thus, changes to their lifespan and growth could have far-reaching effects on other organisms. Sea ice is critical to polar marine ecosystem function, attenuating light and thereby affecting nutrient availability. Sea ice could therefore impact longevity and growth in polar bivalves unless temperature is the overriding factor. Here, we compare the longevity and growth of A. colbecki from two Antarctic sites: Explorers Cove and Bay of Sails, which differ by sea-ice cover, but share similar seawater temperatures, the coldest on Earth (-1.97°C). We hypothesize that scallops from the multiannual sea-ice site will have slower growth and greater longevity. We found maximum ages to be similar at both sites (18–19 years). Growth was slower, with higher inter-individual variability, under multiannual sea ice than under annual sea ice, which we attribute to patchier nutrient availability under multiannual sea ice. Contrary to expectations, A. colbecki growth, but not longevity, is affected by sea-ice duration when temperatures are comparable. Recent dramatic reductions in Antarctic sea ice and predicted temperature increases may irrevocably alter the life histories of this ecosystem engineer and other polar organisms.

This study evaluated the population structure, growth and longevity of Xiphopenaeus kroyeri in the State of Sergipe. The obtained data were compared with other populations on a latitudinal scale in order to evaluate whether the latitudinal paradigm applies to this species. Shrimp sampling took place monthly from September 2013 to August 2014, in nine stations distributed at 5, 15 and 30 m depths, using a shrimp fishery boat equipped with a ‘double rig’ net. Sexual maturity was estimated by the logistic function y = a/(1 + b*exp(-cx)), and the sex ratio was analysed with the Chi-square test. The individual growth rate was estimated using the von Bertalanffy model, and the longevity was estimated by the inverse form of this formula. A total of 6418 (3457 females and 2961 males) was analysed. The size at onset of sexual maturity was 12 mm of carapace length (CL) for males and 12.5 mm CL for females. The total sex ratio did not differ from the expected (1:1). Males exhibited higher growth coefficients (k) and smaller asymptotic growth (CC∞ = 28.74 mm, k = 0.0081 day−1) than females (CC∞ = 30.79 mm, k = 0.0058 day−1). The estimated longevity (years) was 1.55 for males and 2.15 for females. No evident latitudinal pattern was observed regarding the size at onset of sexual maturity or the growth parameters for X. kroyeri. The information found, besides contributing to the knowledge about the biology of this shrimp, can also clarify hypotheses presented in relation to the latitudinal paradigm along the Brazilian coast.

In this editorial, it is strongly advocated that a change of policy is warranted in order to prevent neuroscience from becoming a waste of time and money in the 21st century. Repeating the same trick in different patient populations and perusing the scientific literature seems to currently be the backbone of medical science. However, this approach does not provide knowledge on how the brain works or how specific dysfunctions result in specific diseases. Therefore, earlier findings should, first, be combined to develop new theories on the mechanics of the mind, and, second, these new ideas should be tested in well-designed experiments.

This study presents new information on the population biology, growth and maturation schedules of Galeus melastomus, Centroselachus crepidater and Apristurus aphyodes sampled from the Rockall Trough, a region where deep sea fishing activity has been prevalent for the past 40 years and where shark by-catch is considerable. Both G. melastomus and C. crepidater showed significant sexual size dimorphism with females attaining a greater length and mass. The size (L50) at first maturity was estimated to be 55.6 cm total length (TL) for males and 59.7 cm TL for females in G. melastomus, 57.2 cm TL for males and 75.4 cm TL for females in C. crepidater and 49.0 cm TL for males and 56.9 cm TL for females in A. aphyodes. This represents the first TL50 analysis for Apristurus aphyodes globally. Sharks were aged using a technique which employed cobalt (II) nitrate to stain growth bands in vertebra centra. Band pairs were successfully viewed in G. melastomus and pair counts ranged from 0 to 5 in males and 2 to 7 in females. A higher asymptotic length was deduced from the von Bertalanffy growth equation for females than males (females: L∞ = 69.3 cm; males: L∞ = 60.8 cm) in G. melastomus. Staining was unsuccessful in C. crepidater and A. aphyodes and age could not be determined using this technique.

The curve used until recently by the International Commission for the Conservation ofAtlantic Tunas (ICCAT) to represent the growth of western Atlantic bluefin tuna,Thunnus thynnus, was estimated using tagging information and modalsizes that corresponded primarily to very young fish (ages 1–3, primarily). The estimatedmaximum average size from this curve is very large (382 cm), which could be a result ofthe scarcity of large bluefin in the data used. Recently, scientists have developedtechniques for reading ages from bluefin ear bones (otoliths); the accuracy of the agereadings has been validated with bomb radiocarbon dating. These age readings are primarilyfor large bluefin (ages 5 and older), and indicate slower growth and older ages than waspreviously assumed. However, an analysis of these data resulted in growth curves thatpredicted very small mean sizes for the youngest age group, which could be a result of thelack of small fish in the data used. In this study, we combine the otolith-based agereadings with the size frequency distributions of small (ages 1–3) bluefin caught by purseseiners in the 1970s where the age groups are distinctly statistically as well as visibleto the eye. We analyzed the two datasets jointly using a maximum likelihood approach andassumed that variability in length-at-age increases with age. The resulting growth curvepredicts sizes at young and old ages that are very consistent with observed data such asthe maximum sizes observed in the catch and the modal sizes for very young bluefin. Theresulting curve is also very similar to the curve used by ICCAT for eastern Atlantic andMediterranean bluefin.

A diverse small mammal fauna inhabits the tropical savannas of Kakadu National Park in northern Australia. A detailed long-term capture–mark–recapture study was conducted to estimate body growth parameters in relation to intrinsic and extrinsic factors that may influence them. Three non-linear growth increment functions were compared to determine which one best represented the general growth patterns of nine small mammal species at Kapalga. The von Bertalanffy growth increment function provided the best fit to a pooled species dataset. Hierarchical mixed-effects models were then used to examine variation in body size asymptote and growth and account for non-independence of observations. Model selection was based on the Kullback–Leibler information theoretic approach. As expected, the body size growth constant was correlated to body mass at Kapalga, and body size sexual dimorphism was evident in most species. Difference in body growth constant was only evident in Isoodon macrourus, where females showed accelerated growth. Three of the four marsupial species exhibited either temporal (annual) and spatial (catchment level) variation in body size asymptote, whereas rodent species showed none. There was no clear influence of other extrinsic factors such as fire treatment, rainfall or habitat on body size asymptote or growth rate constant. Our results suggest that body growth is largely controlled by intrinsic factors for each species such as gender in small mammal species at Kapalga. Change in body size and growth caused by human-induced changes to the landscape from factors such as altered fire regimes is unlikely to be substantial for tropical small mammals in northern Australia.

The von Bertalanffy curve was used to examine growth patterns in both body length and mass of female and male polar bears Ursus maritimus live-captured near Svalbard, Norway. A longer growth period in males resulted in pronounced sexual dimorphism in both body length and mass. Males were 1.16 times longer and 2.10 times heavier than females. The asymptotic body length of female and male polar bears from Svalbard was smaller than that for polar bears in four of six previously studied populations. Asymptotic body mass of females from Svalbard was lower than other previously studied populations, while males were generally lighter. The reasons for the lighter bears in Svalbard are unclear, but we believe they were not related to sampling error, ecosystem productivity, or genetic differences. The high pollution load of polar bears in Svalbard may have affected body size but this potential factor could not be assessed. The generally smaller size of polar bears in Svalbard was consistent with density-dependent growth effects but again, information on population density relative to carrying capacity was insufficient to assess this hypothesis.