Diatoms developed a variety of mechanisms to form chain‐like colonies, resulting in diverse morphologies and bulk mechanical properties. These properties affect translation, rotation, and deformation of colonies in ambient flows as well as their susceptibility to breakage by flow‐ and grazer‐induced forces. Morphological characteristics of diatom chains have been extensively studied, yet no studies have examined their mechanical properties. We studied the flexibility of four morphologically distinct species (Lithodesmium undulatum, Stephanopyxis turris, Lauderia annulata, and Guinardia delicatula) by measuring their deflections when held across a capillary tip in developing pipe flow and applying simple beam theory and a finite‐difference analysis of curvature to calculate flexural stiffness. Flexural stiffness varies greatly, with at least four orders of magnitude difference among the examined species (from 1.7 × 10−13 N m2, the most rigid, to 1.3 × 10−17 N m2, the most flexible), but two other species (Melosira nummuloides and a Thalassiosira sp.) were too flexible to measure with our apparatus. Vulnerability to breakage by flow also varied between species and, for species with heavily silicified joints between cells, was enhanced under nutrient depletion. These results highlight yet another attribute underlying the biodiversity of diatoms and their potential for utilizing highly differentiated ecological niches. Quantitative information from this study can now be used in the design of more mechanically realistic models that capture the dynamic coupling between elastic particles and flow to study diatom–flow interactions and their effects on nutrient acquisition, encounter with grazers, aggregate formation, and settling.

The population of the nonindigenous green crab Carcinus maenas (Linnaeus, 1758) in Salem Sound, Massachusetts, USA, was studied over a three-year period from July 2013 through June 2016 using baited traps deployed monthly at five sites. Seasonal catch per unit effort, sex, size, and color were determined and the role of habitat variables, including temperature, salinity, water depth, and substrate, were evaluated. Seasonal catch per unit effort was highest in the fall (October-December), followed by summer (July-September), spring (April-June) and winter (January-March). Few crabs were captured when water temperature dropped below 5 °C. Crabs captured at sites with very fine sand were larger than those captured on other sediment types. Females comprised 73% of the total catch of 7,822 crabs. Only 57 individuals exceeded 70 mm carapace width. Females were larger (mean = 51.7 mm) than males (mean = 48.8 mm). Green-phase crabs comprised 56.8% and red-phase crabs 43.2% of the catch. Green-phase crabs were significantly smaller (mean = 48.1 mm) than red-phase crabs (mean = 53.6 mm, P < 0.0001). Red-phase females were most common in the spring and green-phase in the fall, whereas red-phase males were most common in the spring and fall and green-phase in the summer. A yellow-phase category is proposed as a distinct intermediate between red and green phases. Merits of various types of traps and of bait were evaluated based on different trapping requirements and goals. This is the first investigation of multiple aspects of a population of C. maenas in Massachusetts. The findings should prove useful for researchers studying other populations of C. maenas, as well as for commercial crab fishers or others trapping green crabs for bait, or in efforts to reduce population numbers of this destructive invasive species.

Carcinus maenas (the “shore crab” or “European green crab”) is a very proficient invader (considered to be one of the world’s 100 worst invaders by the IUCN) due to its phenotypic plasticity, wide temperature and salinity tolerance, and an extensive omnivorous diet. Native to Atlantic Europe, it has established two well-studied nonindigenous populations in the northwestern Atlantic and northeastern Pacific and less-studied populations in Australia, Argentina and South Africa. Green crabs are eurythermal and euryhaline as adults, but they are limited to temperate coastlines due to more restrictive temperature requirements for breeding and larval development. They cannot tolerate wave-swept open shores so are found in wave-protected sheltered bays, estuaries and harbors. Carcinus maenas has been the subject of numerous papers, with over 1000 published in the past decade. This review provides an up-to-date account of the current published information on the life history and population dynamics of this very important species, including genetic differentiation, habitat preferences, physical parameter tolerances, reproduction and larval development, sizes of crabs, densities of populations, sex ratios, ecosystem dynamics and ecological impacts in the various established global populations of green crabs.

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1. A table of previous descriptions of larvae of Diogenidae is given. 2. Larvae of the hermit crab Clibanarius vittatus were reared on a diet of Artemia nauplii. Five, rarely four, zoeal stages and megalopa were obtained. Duration, mortality and sizes of larvae from two hatches are listed. 3. Detailed descriptions and figures for each larval stage are presented.

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