Author: Kohei Saito

Abstract

When the existing order cannot offer a solution, the solution to climate crisis must come from the radical left, and this is precisely why Karl Marx’s idea of ecosocialism is more important than ever. In this context, it is worth revisiting not only the legacy of István Mészáros’s theory of ‘social metabolism’ and that of his successors – who can be categorised as comprising the ‘metabolic rift school’, which includes John Bellamy Foster, Paul Burkett, and Brett Clark –, but also Karl Marx’s own theory of metabolism. In order to highlight the contemporary importance of Marx’s theory of metabolism after its long suppression in the twentieth century, this paper aims at classifying the three different levels of Marx’s concept of ‘metabolic rift’, which also entails clarifying three different levels of ‘metabolic shift’ as the theoretical foundation for updating Marx’s theory of postcapitalism in the age of global ecological crisis.

In: Historical Materialism

Pelagic Mysidacea and Decapoda have important roles in marine ecosystems. However, information on their life histories is extremely limited. This study aimed to evaluate the life cycles of pelagic Mysidacea and Decapoda in the Oyashio region, Japan. Production of the four dominant species was estimated by combining body mass (DM) data and abundance data. Mysidacea belonging to 5 species from 5 genera occurred in the study area. Their abundance and biomass ranged between 11.7-50.1 ind. m−2 and 1.2-7.9 g wet mass (WM) m−2, respectively. Six species from 6 genera belonged to Decapoda, and their abundance and biomass ranged between 9.0-17.3 ind. m−2 and 3.0-17.3 g WM m−2, respectively. Based on body length histograms, there were two to four cohorts for the three dominant mysids and one dominant decapod on each sampling date. Life histories of the two numerically dominant mysids (Eucopia australis and Boreomysis californica) followed similar patterns: recruitment of young in May, strong growth from April to June, and a longevity of three years. Life cycles of the two minor species (the mysid Meterythrops microphthalma and the decapod Hymenodora frontalis) were not clear because of their low abundance. The timing of recruitment of the young and the strong juvenile growth for the two dominant mysids corresponds with the season when their prey is abundant. The annual production of the dominant mysid species was 14.0 mg DM m−2 (B. californica) and 191.8 mg DM m−2 (E. australis). Annual production/biomass (PB) ratios ranged between 0.242 (H. frontalis) and 0.643 (M. microphthalma). Compared with other regions, the Oyashio region showed high production and low PB ratios. The high production in the Oyashio region may be related to the high biomass of these species. Because of the low temperature conditions (3°C), pelagic mysids and decapods in the Oyashio region may have slower growth, longer generation times and lower PB ratios than in other oceans.

In: Crustaceana

Seasonal changes in body size (prosome length: PL) and oil sac volume (OSV) of the three most numerically abundant copepods in Ishikari Bay, northern Sea of Japan, Paracalanus parvus (Claus, 1863), Pseudocalanus newmani Frost, 1989 and Oithona similis Claus, 1866, were studied using monthly samples collected through vertical hauls of a 100-μm mesh NORPAC net from March, 2001 to May, 2002. Seasonal changes in PL were common for the three species and were more pronounced during a cold spring. PL was negatively correlated with temperature, and this relationship was described well using the Bělehrádek equation. Seasonal changes in OSV exhibited a species-specific pattern, i.e., OSV was greater during a warm summer for P. parvus and was greater during a cold spring for P. newmani and O. similis. The OSV peak period corresponded with the optimal thermal season of each species. The relative OSV to prosome volume of the small copepods (0.6-0.8%) was substantially lower than that of the large copepods (20-32%). These facts suggest that the oil sac of small copepods is not used for overwintering or diapauses or during periods of food scarcity, but is instead used as the primary energy source for reproduction, which occurs during the optimum thermal season of each species.

In: Crustaceana