Density‐dependent feedbacks, hysteresis, and demography of overgrazing sea urchins

Can sea urchins beat the heat? Sea urchins, thermal tolerance and climate change

The massive die-off of the long-spined sea urchin, Diadema antillarum, a significant reef grazer, in the mid 1980s was followed by phase shifts from coral dominated to macroalgae dominated reefs in the Caribbean. While Diadema populations have recovered in some reefs with concomitant increases in coral cover, the additional threat of increasing temperatures due to global climate change has not ...

Gonadal growth and maturation of sea urchins

characterized by intra-gonadal nutrient storage and its use for gametogenesis (Walker et al., 2001). Sea urchin gonads contain two main types of cells: germ cells and nutritive phagocytes, somatic cells common in both sexes that store nutrients necessary for gametogenesis (Walker, 1982). Before the initiation of gametogenesis, the gonads increase in size by accumulating nutrients such as protei...

REpROdUCTIvE ISOLATION BETwEEN SpECIES OF SEA URChINS

Existing knowledge on reproductive isolating barriers between sea urchin species is reviewed. Experiments involving artificial production of hybrids between congeneric echinoid species have shown that in most cases hybrids are viable and capable of backcrossing. Only species separated for > 5 million yrs show complete post-zygotic isolation. Each potential prezygotic isolating barrier appears t...

Pentamerism and Modularity in Sea Urchins

Phase-Shift Dynamics of Sea Urchin Overgrazing on Nutrified Reefs

Shifts from productive kelp beds to impoverished sea urchin barrens occur globally and represent a wholesale change to the ecology of sub-tidal temperate reefs. Although the theory of shifts between alternative stable states is well advanced, there are few field studies detailing the dynamics of these kinds of transitions. In this study, sea urchin herbivory (a 'top-down' driver of ecosystems) ...