Ocean acidification induces multi-generational decline in copepod naupliar production with possible conflict for reproductive resource allocation

Climate change, including ocean acidification (OA), presents fundamental challenges to marine biodiversity and sustained ecosystem health. We determined reproductive response (measured as naupliar production), cuticle composition and stage specific growth of the copepod Tisbe battagliai over three generations at four pH conditions (pH 7.67, 7.82, 7.95, and 8.06). Naupliar production increased significantly at pH 7.95 compared with pH 8.06 followed by a decline at pH 7.82. Naupliar production at pH 7.67 was higher than pH 7.82. We attribute the increase at pH 7.95 to an initial stress response which was succeeded by a hormesis-like response at pH 7.67. A multi-generational modelling approach predicted a gradual decline in naupliar production over the next 100 years (equivalent to approximately 2430 generations). There was a significant growth reduction (mean length integrated across developmental stage) relative to controls. There was a significant increase in the proportion of carbon relative to oxygen within the cuticle as seawater pH decreased. Changes in growth, cuticle composition and naupliar production strongly suggest that copepods subjected to OA-induced stress preferentially reallocate resources towards maintaining reproductive output at the expense of somatic growth and cuticle composition. These responses may drive shifts in life history strategies that favour smaller brood sizes, females and perhaps later maturing females, with the potential to profoundly destabilise marine trophodynamics

FINE STRUCTURE AND SECRETORY ACTIVITY OF THE SPERMATHECA OF THE FRESHWATER CRAB PARATELPHUSA HYDRODROMOUS (CRUSTACEA : DECAPODA)

The multifibrilar musculature that encircles the spermathecal epithelium of Paratelphusa hydrodromous is composed of slow acting fibres characterized by the abundance of sarcoplasm, scarcity of myofibrils, lack of division of myofibrils into sacrcomeres, absence of T-system, poorly developed sarcoplasmic reticulum and sparseness in mitochondria. The secretory epithelium is composed of a single type of columnar cell with basally located multinucleolated nuclei. OctoberNovember (the pre-breeding season) is the period of synthesis of intrinsic secretion of the spermathecal epithelial cells. The mode of release of secretion is apocrine and occurs towards the end of the pre-breeding season