Patterns and impacts of inorganic tripton in Cayuga Lake

Inorganic tripton in the upper waters of Cayuga Lake, NY, is characterized, quantified and contrasted for shallow (<6 m) and deep (>100 m) water regions based on analyses with scanning electron microscopy equipped with automated image analysis and X-ray energy spectroscopy (SAX) of samples collected in 1999 and 2000. The impacts of this material on water clarity and the phosphorus (P) pool are evaluated based on paired measurements of turbidity (T _n), Secchi disc transparency (SD), chlorophyll, and four fractions of particulate P (PP) determined according to selective extraction protocols. The major components of inorganic tripton in the lake are reported to be clay minerals and quartz, received from the watershed, and calcium carbonate (CaCO₃), that is produced internally. Clay minerals are the dominant component in a shallow region that receives tributary inflows. CaCO₃, precipitated during a mid-summer whiting event, is reported to be the dominant component of inorganic tripton for the deep water region for a low runoff year, while clays can become dominant in these areas after prolonged intervals of high runoff. It is demonstrated that inorganic tripton, rather than phytoplankton, is the primary regulator of T _n and SD, it represents most of the PP, and is primarily responsible for the higher T _n, lower SD, and higher TP in the shallow area compared to the deep water region. Efforts to improve clarity in this shallow region of the lake should consider the feasibility of controlling the input of terrigenous suspensoids rather than reductions in P loading.     

Diffusive instabilities in a one-dimensional temperature-dependent model system for a mite predator-prey interaction on fruit trees: dispersal motility and aggregative preytaxis effects

A weakly nonlinear analysis relevant to the formation of one-dimensional spatial patterns generated by diffusive instabilities is performed on a particular interaction-diffusion model for a temperature-dependent predator-prey mite system on fruit trees. The bifurcation from a uniform steady state is of a subcritical nature in a low temperature-low population interval while in a high temperature-high population one there exist temperatures for which it can be supercritical resulting in a family of parallel stripes. The occurrence of such population clumping, caused both by the predator's having a sufficient dispersal advantage and by its strongly stabilizing tendency toward preytactic aggregation lying in some critical range, may help explain the inhomogeneous ecological patterns exhibited by phytophagous arthropods found on uniformly distributed vegetation or on plants grown in monocultures.