Fig. 1 depicts the several factors influencing policy effectiveness for
the case of fertilizer ordinances and Florida red tides. The effectiveness
of a policy such as a municipal or county fertilizer ordinance depends
upon: (i) the physical linkage between anthropogenic nutrients
and algal blooms (specifically, blooms of the harmful marine alga,
K. brevis); and (ii) human adherence to the policies. Both are uncertain
(as depicted in the figure by dotted lines or boxes). Importantly, the relative
contributions of nature- and human-sourced nutrients to K. brevis
blooms are uncertain, and they may be idiosyncratic. As discussed in the
next section, government agencies and stakeholders have argued for
clear linkages, leading to the implementation of TMDL policies, including
fertilizer ordinances among others. An ongoing scientific debate
and inadequate public education adversely affect human understanding
of the linkage between nutrients and blooms. If human understanding
of this linkage, and therefore the rationale for the policy,were more certain,
it would positively affect human adherence. The potential impacts
of reductions in lawn fertilizer applications on home values, the likely
contravention of cultural norms (such as those relating to property appearance),
and the opposition of the fertilizer industry to local ordinances,
also may reduce adherence.