Yes. The data is being served out on an ArcGIS Server here and I access it through its REST url. You said earlier that you could output your data as a csv. You could use the dojo's CsvStore function to load your csv file and within the CsvStore function there is a query option to retrieve only those points you want to be displayed. Here's a snippet that might start you in the right direction:
var species_name = "Karenia brevis";
var dataStore = new dojox.data.CsvStore({url:"data.csv"});
dataStore.fetch({
query:{species: species_name},
onComplete: function(items, request) {
dojo.forEach(items, function(item, index) {
var lat = dataStore.getValue(item, "Latitude");
var lon = dataStore.getValue(item, "Longitude");
var symbol = new esri.symbol.SimpleMarkerSymbol();
var latitude = parseFloat(lat);
var longitude = parseFloat(lon);
var geometry = new esri.geometry.Point(longitude,latitude);
geometry = esri.geometry.geographicToWebMercator(geometry);
dataLayer.add(new esri.Graphic(geometry, symbol));
});
},
onError: function(error) {
alert("Unable to read data file");
}
});
It's a bit more complicated just because you are having to read your points in via a data store vs a map service. As long as your csv file is on the same server as your JS API, you don't have to use a proxy service.
I don't know how you can retrieve the data you have posted out on ArcGIS Online so you will need to get some help from ESRI about doing that. I've never done that before.
