Measures　based　on　concurrent　alterations　of　an　environment＇s　physical,　chemical,　and　biological　factors　are　commonly　adopted　to　control　harmful　algal　blooms　(HABs).　It　was　postulated　that　the　combinations　and　interactions　of　multiple　measures　could　exert　cumulative　effects　(as　the　overall　effect　may　or　may　not　be　equal　to　the　additive　sum　for　each　measure　individually).　However,　few　studies　have　further　assessed　whether　the　cumulative　effect　is　synergistic,　additive,　or　antagonistic.　This　study　proposed　a　framework　to　distinguish　and　quantify　the　cumulative　effects.　We　also　designed　an　experiment　to　investigate　the　cumulative　effect　of　the　combined　utilization　of　physical　(flow　velocity),　chemical　(copper),　and　biological　(propionamide)　measures　on　algae　growth　inhibition.　The　results　show　that　the　cumulative　effect　of　physical　and　chemical　measures　on　algae　growth　inhibition　was　antagonistic;　the　cumulative　effect　of　physical　and　biological　measures　was　antagonistic;　the　cumulative　effect　of　chemical　and　biological　measures　was　synergistic,　and　the　cumulative　effect　of　all　the　measures　together　tended　to　be　antagonistic.　These　results　showed　that　the　synergistic　interactions　between　chemical　and　biological　measures　produced　antagonistic　effects　when　physical　measures　were　added.　Through　response　surface　methodology　analysis,　we　also　found　that　the　physical　factor　was　the　most　significant　factor　affecting　the　cumulative　effect,　followed　by　the　chemical　factor　and　then　the　biological　factor.　Our　results　provide　a　more　detailed　understanding　of　the　interaction　patterns　among　multiple　measures　that　affect　algal　growth.　Importantly,　this　understanding　can　be　further　integrated　into　future　strategy　development　to　fully　exploit　the　potential　of　the　cumulative　effect　at　its　maximum　performance.