'algae-laden' originates from Modern English, specifically the compound of 'algae' and 'laden'. 'algae' comes from New Latin 'alga' meaning 'seaweed', and 'laden' comes from Old English 'hlādan' (to load) via Middle English.

'algae' entered English from New Latin 'alga' (plural 'algae'), while 'laden' developed from Old English 'hlādan' to Middle English 'laden' and retained the sense 'loaded' or 'burdened'. The modern compound 'algae-laden' arose by combining these elements to mean 'burdened with algae'.

The components originally meant 'seaweed' ('alga') and 'loaded/burdened' ('laden'); when combined they came to mean 'covered or burdened with seaweed/algae', a literal extension that has remained stable.