Paleoenvironmental reconstruction in La Paz Bay, Gulf of California: Evidence from δ18O in Chione californiensis

Oceanic characteristics of the Holocene are used to understand climatic patterns and phenomena that affect marine and human communities. Likewise, past marine conditions can be reconstructed from surface sea temperature (SST), using stable oxygen isotopes in bivalve shells. The objective of this study was to calculate Holocene summer SSTs for La Paz Bay, by analyzing δ18O of 14C dated bivalve shells ( Chione californiensis) from a Holocene camp site located in Cañada de La Enfermería, Baja California Sur, México. Aragonite was extracted from the shells’ umbo, representing the summer growth season during the first year of life. δ18O value of C. californiensis is −1.9 ± 0.1‰ at present, and varied between −1.3‰ and −2.6‰ during the last 9 ky. In 9469 BP, 8396 BP, and 7708 BP, δ18O values were similar to those of the present. In 7857 BP, 7805 BP, and 7804 BP, δ18O was 18O depleted (0.6–0.9‰), indicating warmer summer SSTs versus the present. In 7070 BP, 6945 BP, and 2087 BP, δ18O was enriched in 18O (0.3–0.4‰), suggesting colder SSTs versus the present. This study coincides with other paleotemperature studies for the region and allows us to address the effect of changing SST on this marine resource, its use by human communities of the past, and its effects on human presence in the area with respect to climate variability.

Lifelong divergence of growth patterns in Arctic charr life history strategies: implications for sustainable fisheries in a changing climate

Arctic charr (Salvelinus alpinus Linneaus, 1758) are phenotypically variable with multiple life history strategies including anadromous and freshwater resident individuals. The mechanism determining life history is believed to be set early in life. Anadromous individuals show greater seasonality in growth and feeding after the first seaward migration relative to resident conspecifics. We used otolith growth increment measurements to estimate lifelong growth patterns for 355 individuals with anadromous or resident life history from four populations within Cumberland Sound, Nunavut. Using a general and a generalized linear model, we discovered a linear increase (estimate = 0.006) in growth for both Arctic charr life histories between 1990 and 2016. Resident Arctic charr have lower annual growth (estimate = -0.176) and show a decrease in the annual proportion of summer growth as they age (estimate = -0.042) while their anadromous counterparts maintain a higher seasonality in their growth patterns with age. This suggests that growth is indeed important in life history trajectory for Arctic charr and that seasonal growth patterns differ among life histories. The results highlight the importance of improving our understanding of mechanisms influencing life history trajectory in Arctic charr to ensure sustainability of harvested Arctic charr populations in a changing climate.

Can Center-Based Care Reduce Summer Slowdown Prior to Kindergarten? Exploring Variation by Family Income, Race/Ethnicity, and Dual Language Learner Status

This study examines growth in language and math skills during the summer before kindergarten; considers variation by family income, race/ethnicity, and dual language learner status; and tests whether summer center-based care sustains preschool gains. Growth in skills slowed during summer for all children, but the patterns varied by domain and group. Non-White and dual language learner students showed the largest drop-off in language skills during summer. Lower-income students demonstrated slower summer growth in math skills than their higher-income peers. Students enrolled in summer center-based care had faster growth in math skills than those who did not attend care. Yet lower-income students who attended center-based care showed slower growth in language skills during summer than similar nonattenders. Implications are discussed.

Science-based approach to using growth rate to assess coral performance and restoration outcomes

One response to the coral reef crisis has been human intervention to enhance selection on the fittest corals through cultivation. This requires genotypes to be identified for intervention, with a primary basis for this choice being growth: corals that quickly grow on contemporary reefs might be future winners. To test for temporal stability of growth as a predictor of future performance, genotypes of the coral Porites spp. were grown in common gardens in Mo'orea, French Polynesia. Growth was measured every two to four months throughout 2018, and each period was used as a predictor of growth over the subsequent period. Area-normalized growth explained less than 29% of the variance in subsequent growth, but for biomass-normalized growth this increased to 45–60%, and was highest when summer growth was used to predict autumn growth. The capacity of initial growth to predict future performance is dependent on the units of measurement and the time of year in which it is measured. The final choice of traits to quantify performance must be informed through consideration of the species and the normalization that best capture the information inherent in the biological processes mediating variation in traits values.

Windbreaks as part of climate-smart landscapes reduce evapotranspiration in vineyards, Western Cape Province, South Africa

Under the conditions of climate change in South Africa, ecological and technical measures are needed to reduce the water consumption of irrigated crops. Windbreak hedges are long-rated systems in agriculture that significantly reduce wind speed. Their possibilities to reduce evapotranspiration and water demand are being investigated at a vineyard in the Western Cape Province, South Africa. Detailed measurements of meteorological parameters relevant for the computation of reference and crop-specific evapotranspiration following the FAO 56 approaches within a vineyard in the Western Cape Province of South Africa have shown the beneficial effect of an existing hedgerow consisting of 6 m high poplars (Populus simonii (Carrière) Wesm.). With reference to a control station in the open field, the mean wind speed in a position about 18 m from the hedgerow at canopy level (2 m) was reduced by 27.6% over the entire year and by 39.2% over the summer growing season. This effect leads to a parallel reduction of reference evapotranspiration of 15.5% during the whole year and of 18.4% over the growing season. When applying empirical crop-specific K_c values for well-irrigated grapes, the reduction of evapotranspiration is 18.8% over the summer growth period. The introduced tree shelterbelts are a suitable eco-engineering approach to reduce water consumption and to enhance water saving in vineyards.

Bioconditioning of Arctic Waters and Stimulation of Arctic Phytoplankton by Sea Ice Algae: Vulnerability to Increased Light

Arctic sea ice algae produce extracellular organic products, which, as bioconditioners of seawater, may stimulate early summer growth of pelagic, under-sea-ice phytoplankton in low light and low temperature conditions. Sea ice algae are inhibited or decline in numbers if prematurely exposed to high light conditions, thereby reducing their ability to produce bioconditioners. As climate change creates an early reduction or removal of snow and sea ice cover, the result may be a decrease in primary phytoplankton production.

Contributions at Capitalization Study on Chemical Content from Mulberry Tree Leave by Bombyx Mori Larvae

In order to assess how efficient is the use of mulberry leaf by the Bombyx mori Baneasa Super larvae hybrid, some determinations were made regarding the nutritional value and digestibility of the worm leaf administered as food, during a series of summer growth. The results showed that ongoing vegetation and growth process of this hybrid, the Mulberry leaves suffer an aging phenomenon, revealed by diminishing its chemical composition quality. According to this, most of the nutritional substances from mulberry leaves, except cellulose, manifest a continuous decline during the growth period. The digestibility of these nutritional components registered a value of 56.41%, the crude energy value was 4209 kcal/kg dry substance, and digestive energy was 2173 kcal/kg (DS), while the metabolic energy was 2044-2007 kcal/kg (DS). The efficiency of converting ingestion into silk had a value of 9.30% and the digestion was 15.76%.

Contributions at Capitalization Study on Chemical Content from Mulberry Tree Leave by Bombyx Mori Larvae

In order to assess how efficient is the use of mulberry leaf by the Bombyx mori Baneasa Super larvae hybrid, some determinations were made regarding the nutritional value and digestibility of the worm leaf administered as food, during a series of summer growth. The results showed that ongoing vegetation and growth process of this hybrid, the Mulberry leaves suffer an aging phenomenon, revealed by diminishing its chemical composition quality. According to this, most of the nutritional substances from mulberry leaves, except cellulose, manifest a continuous decline during the growth period. The digestibility of these nutritional components registered a value of 56.41%, the crude energy value was 4209 kcal/kg dry substance, and digestive energy was 2173 kcal/kg (DS), while the metabolic energy was 2044-2007 kcal/kg (DS). The efficiency of converting ingestion into silk had a value of 9.30% and the digestion was 15.76%. Keywords: leaves, mulberry, larvae, energy, use