With an increase in blooms of harmful algae on both national and global levels, it is becoming ever more important to be able to detect these organisms at high spatial and temporal resolutions. It is also imperative that methods of detection are able to identify target cells at low concentrations. To this end we present a number of immunologically-based techniques for detecting cells of Aureococcus anophagefferens, the cause of ’¡ÈBrown Tides’¡É off the Mid-Atlantic coast. These techniques include flow cytometry, enzyme-linked immunosorbent assay (ELISA), quartz crystal microbalance (QCM), and atomic force microscopy (AFM).