if (document.images) {

// subnav over images
    img6on = new Image();
    img6on.src = "images/subnav/intro_over.gif";
    img7on = new Image();
    img7on.src = "images/subnav/staff_over.gif";
    img8on = new Image();
    img8on.src = "images/subnav/news_over.gif";
    img9on = new Image();
    img9on.src = "images/subnav/project_cat_over.gif";
    img10on = new Image();
    img10on.src = "images/subnav/project_region_over.gif";
    img11on = new Image();
    img11on.src = "images/subnav/project_web_over.gif";
    img12on = new Image();
    img12on.src = "images/subnav/reports_over.gif";
    img13on = new Image();
    img13on.src = "images/subnav/papers_over.gif";
    img14on = new Image();
    img14on.src = "images/subnav/contact_over.gif";
    img15on = new Image();
    img15on.src = "images/subnav/sustain_over.gif";
    img16on = new Image();
    img16on.src = "images/subnav/tropeca_over.gif";
    img17on = new Image();
    img17on.src = "images/subnav/invest_over.gif";
    img18on = new Image();
    img18on.src = "images/subnav/directory_over.gif";
    img19on = new Image();
    img19on.src = "images/subnav/seafeeds_over.gif";
    img20on = new Image();
    img20on.src = "images/subnav/biodiversity_over.gif";
    img21on = new Image();
    img21on.src = "images/subnav/news_archive_over.gif";
    
// staff nav over images
    img001on = new Image();
    img001on.src = "images/subnav/crick_over.gif";
    img002on = new Image();
    img002on.src = "images/subnav/john_over.gif";
    img003on = new Image();
    img003on.src = "images/subnav/paul_over.gif";
    img004on = new Image();
    img004on.src = "images/subnav/tristan_over.gif";
    img005on = new Image();
    img005on.src = "images/subnav/another_over.gif";
    img006on = new Image();
    img006on.src = "images/subnav/nick_over.gif";
    img007on = new Image();
    img007on.src = "images/subnav/myriam_over.gif";
    
// web resources subnav over images
    imgWeb01on = new Image();
    imgWeb01on.src = "images/subnav/tropeca/bgd_over.gif";
    imgWeb02on = new Image();
    imgWeb02on.src = "images/subnav/tropeca/aims_over.gif";
    imgWeb03on = new Image();
    imgWeb03on.src = "images/subnav/tropeca/news_over.gif";
    imgWeb04on = new Image();
    imgWeb04on.src = "images/subnav/tropeca/downloads_over.gif";
    imgWeb05on = new Image();
    imgWeb05on.src = "images/subnav/tropeca/links_over.gif";


// subnav off images
    img6off = new Image();
    img6off.src = "images/subnav/intro_off.gif";
    img7off = new Image();
    img7off.src = "images/subnav/staff_off.gif";
    img8off = new Image();
    img8off.src = "images/subnav/news_off.gif";
    img9off = new Image();
    img9off.src = "images/subnav/project_cat_off.gif";
    img10off = new Image();
    img10off.src = "images/subnav/project_region_off.gif";
    img11off = new Image();
    img11off.src = "images/subnav/project_web_off.gif";
    img12off = new Image();
    img12off.src = "images/subnav/reports_off.gif";
    img13off = new Image();
    img13off.src = "images/subnav/papers_off.gif";
    img14off = new Image();
    img14off.src = "images/subnav/contact_off.gif";
    img15off = new Image();
    img15off.src = "images/subnav/sustain_off.gif";
    img16off = new Image();
    img16off.src = "images/subnav/tropeca_off.gif";
    img17off = new Image();
    img17off.src = "images/subnav/invest_off.gif";
    img18off = new Image();
    img18off.src = "images/subnav/directory_off.gif";
    img19off = new Image();
    img19off.src = "images/subnav/seafeeds_off.gif";
    img20off = new Image();
    img20off.src = "images/subnav/biodiversity_off.gif";
    img21off = new Image();
    img21off.src = "images/subnav/news_archive_off.gif";


// staff nav off images
    img001off = new Image();
    img001off.src = "images/subnav/crick_off.gif";
    img002off = new Image();
    img002off.src = "images/subnav/john_off.gif";
    img003off = new Image();
    img003off.src = "images/subnav/paul_off.gif";
    img004off = new Image();
    img004off.src = "images/subnav/tristan_off.gif";
    img005off = new Image();
    img005off.src = "images/subnav/another_off.gif";
    img006off = new Image();
    img006off.src = "images/subnav/nick_off.gif";
    img007off = new Image();
    img007off.src = "images/subnav/myriam_off.gif";
    
// web resources subnav over images
    imgWeb01off = new Image();
    imgWeb01off.src = "images/subnav/tropeca/bgd_off.gif";
    imgWeb02off = new Image();
    imgWeb02off.src = "images/subnav/tropeca/aims_off.gif";
    imgWeb03off = new Image();
    imgWeb03off.src = "images/subnav/tropeca/news_off.gif";
    imgWeb04off = new Image();
    imgWeb04off.src = "images/subnav/tropeca/downloads_off.gif";
    imgWeb05off = new Image();
    imgWeb05off.src = "images/subnav/tropeca/links_off.gif";

}

function imgOn(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "on.src");
        }
}

function imgOff(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "off.src");
        }
}