We describe size at age, growth, and population structure of short-finned squid (Illex illecebrosus) from Newfoundland waters during 1990. Ages were estimated from statolith increment counts and used to back-calculate hatching dates. Hatching ranged between December and June with the hatching months of March to May predominating. Constant interchange of individuals in the inshore population was evident in that the modal month of hatching progressed from March within the earliest (July) sample to May within the latest (November) sample. Within the mantle length range available, growth was adequately expressed by a linear model. Females grew faster than males, and during the March to May months of hatching, length at age and growth rate increased with hatching month. This positive effect of late time of hatching was also seen in growth in mass and in gonad development and sexual maturation.
Martian soils are critically important for understanding the history of Mars, past potentially habitable environments, returned samples, and future human exploration. This paper examines soil crusts on the floor of Jezero crater encountered during initial phases of the Mars 2020 mission. Soil surface crusts have been observed on Mars at other locations, starting with the two Viking Lander missions. Rover observations show that soil crusts are also common across the floor of Jezero crater, revealed in 45 of 101 locations where rover wheels disturbed the soil surface, 2 out of 7 helicopter flights that crossed the wheel tracks, and 4 of 8 abrasion/drilling sites. Most soils measured by the SuperCam laser‐induced breakdown spectroscopy (LIBS) instrument show high hydrogen content at the surface, and fine‐grained soils also show a visible/near infrared (VISIR) 1.9 µm H2O absorption feature. The Planetary Instrument for X‐ray Lithochemistry (PIXL) and SuperCam observations suggest the presence of salts at the surface of rocks and soils. The correlation of S and Cl contents with H contents in SuperCam LIBS measurements suggests that the salts present are likely hydrated. On the “Naltsos” target, magnesium and sulfur are correlated in PIXL measurements, and Mg is tightly correlated with H at the SuperCam points, suggesting hydrated Mg‐sulfates. Mars Environmental Dynamics Analyzer (MEDA) observations indicate possible frost events and potential changes in the hydration of Mg‐sulfate salts. Jezero crater soil crusts may therefore form by salts that are hydrated by changes in relative humidity and frost events, cementing the soil surface together.
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