Mapping Disturbances in Time and Space

The GIS platform is in the process of being upgraded. If you have a highspeed internet connection, you may click here to see a transitional product.


All HEED MD data can be accessed using three critical parameters TIME, SPACE, and THEMATIC CATEGORY. A Java-based application running from your web browser permits visualization and exploration of these data parameters.

The purpose of plotting occurrences on maps is to obtain a global and visual overview of marine disturbance events over time. Information uniformly plotted on maps implies there is regular monitoring of sites (e.g. phytoplankton and/or phycotoxins), however, this assumption is usually false. Any indication of the frequency of events must be understood to include only presence data not absence data. Occurrences may have increased over time but these data can only indicate that observational effort has increased over time until a final absence layer or quality control process is completed. Also presumed is that survey methods during the 1995-1997,1998 and 2001 data entry sessions were consistent, complete and accurate (not necessarily the case.... a re-survey is yet to be conducted using present techniques).

Each map view by default represents more than one type of event, the different types of events are too numerous to list: but include the broadest spectrum of animal and plant mortality, blooms, and toxicity that were not directly attributed to human inputs. The information plotted shows the presence of toxins, or observations of mortality. Blooms of potentially toxic species with non detectable levels of toxicity, however, do not appear on maps.

Not all queries are appropriate or reasonable given the “normalization� of the data within the relational database. Functionality has been provided to search for information from individual fields within the database using key words. Some prescribed relational queries are also provided. BEWARE some queries of large portions of the database will consume available system memory.