Herbivore and nutrient impact on primary producer assemblages in a tropical marine environment

Globally, human populations are increasing and coastal ecosystems are becoming increasingly impacted by anthropogenic stressors. As eutrophication and exploitation of coastal resources increases, primary producer response to these drivers becomes a key indicator of ecosystem stability. Despite the importance of monitoring primary producers such as seagrasses and macroalgae, detailed studies on the response of these benthic habitat components to drivers remain relatively sparse. Utilizing a multi-faceted examination of turtle-seagrass and sea urchin-macroalgae consumer and nutrient dynamics, I elucidate the impact of these drivers in Akumal, Quintana Roo, Mexico. In Yal Ku Lagoon, macroalgae bioindicators signified high nutrient availability, which is important for further studies, but did not consistently follow published trends reflecting decreased δ 15N content with distance from suspected source. In Akumal Bay, eutrophication and grazing by turtles and fishes combine to structure patches within the seagrass beds. Grazed seagrass patches had higher structural complexity and productivity than patches continually grazed by turtles and fishes. Results from this study indicate that patch abandonment may follow giving-up density theory, the first to be recorded in the marine environment. As Diadema antillarum populations recover after their massive mortality thirty years ago, the role these echinoids will have in reducing macroalgae cover and altering ecosystem state remains to be clear. Although Diadema antillarum densities within the coral reef ecosystem were comparable to other regions within the Caribbean, the echinoid population in Akumal Bay was an insufficient driver to prevent dominance of a turf-algal-sediment (TAS) state. After a four year study, declining coral cover coupled with increased algal cover suggests that the TAS-dominated state is likely to persist over time despite echinoid recovery. Studies on macroalgal diversity and nutrients within this same region of echinoids indicated diversity and nutrient content of macroalgae increased, which may further increase the persistence of the algal-dominated state. This study provides valuable insight into the variable effects of herbivores and nutrients on primary producers within a tropical coastal ecosystem. Results from this work challenge many of the currently accepted theories on primary producer response to nutrients and herbivory while providing a framework for further studies into these dynamics.

Matrifocality and child shifting among the low income earners in Jamaica

Jamaican family structures have long felt the impact of unstable internal economic conditions and high volume of labor demands originating from England, Canada, the United States, and other larger societies. In response to the economic conditions and labor demands, increasing numbers of Jamaican women have migrated away from home, both within Jamaica and to other countries. Subsequently, many Jamaicans' households are restructured using a method called child shifting. This refers to "the relocation of children between households." Using three major theoretical paradigms: cultural diffusion, social pathology, and structural functionalism, this study explores the literature of child shifting to understand how economic conditions influence matrifocal families and in particular their child rearing practices. This study employs the structural functionalism paradigm's focus on "adaptive responses" to find plausible explanations for child shifting patterns. The primary premise of the "adaptive responses" approach is that economic marginality leads to certain adaptive responses in residential, kinship, and child rearing patterns. This study finds certain adjustment problems associated with child shifting. These include shifted children developing feelings of abandonment, of anxiety, of loss, and having difficulty trusting after the shifting occurs. These costs may outweigh the benefits of child shifting.