During an ecological survey of a saltmarsh estuary, a researcher wishes to estimate the population sizes of two species: the European glasswort ($Salicornia\; europaea$), a sessile halophyte, and the common shore crab ($Carcinus\; maenas$), a highly motile decapod.

Which of the following describes appropriate protocols for estimating the population sizes of these species?

1. For $S.\; europaea$, lay out a grid over the saltmarsh, generate random coordinates, place frame quadrats at these coordinates, and count the individuals in each to calculate a mean density.
2. For $C.\; maenas$, lay out a belt transect perpendicular to the shoreline, place quadrats at 5 m intervals, and count the crabs within each quadrat.
3. For $C.\; maenas$, capture individuals using baited traps, mark each crab with a small dab of non-toxic, water-resistant paint on its carapace, release them, and recapture a second sample after $24hours$ to calculate the Lincoln Index.