Dissolved　inorganic　and　organic　carbons　(DIC　and　DOC)　provide　two　of　the　largest　pools　of　carbon　in　the　ocean.　However,　limited　information　is　available　concerning　the　relationship　between　DIC　and　different　constituents　of　dissolved　organic　matter　(DOM),　such　as　fluorescent　compounds.　This　study　investigates　the　dynamics　of　DOM　and　their　implications　for　carbon　and　nutrient　cycling　in　the　east　Taiwan　Strait,　using　DOC,　absorption　spectroscopy,　and　fluorescence　excitation-emission　matrices-parallel　factor　analysis　(EEM-PARAFAC).　The　study　area　was　dominated　by　the　waters　from　the　South　China　Sea　during　the　sampling　period　in　summer　2013.　The　dynamics　of　DOM　were　influenced　strongly　by　microbial　activities,　as　indicated　by　the　close　correlations　(the　absolute　value　of　r:　0.75–0.97,　p ＜ 0.001)　between　apparent　oxygen　utilization　(AOU)　and　DOM　parameters,　including　DOC,　the　absorption　coefficient　at　280 nm,　the　fluorescence　intensity　of　protein-like　component　C3,　and　the　humification　index　HIX.　The　contribution　of　DOC　degradation　to　the　net　increase　in　DIC　was　approximately　15%　and　21%　in　the　north　and　the　south　of　the　east　Taiwan　Strait,　respectively.　The　DIC　was　correlated　negatively　with　protein-like　fluorescence,　revealing　the　production　of　DIC　by　the　microbial　degradation　of　labile　components.　The　DIC　was　correlated　positively　with　humic-like　fluorescence　and　HIX,　suggesting　that　the　storage　of　carbon　by　produced　refractory　humic　substances　could　not　compensate　for　the　release　of　DIC　in　the　deeper　waters.　The　correlations　of　nutrients　with　DOM　parameters　were　similar　to　those　of　DIC,　further　indicating　the　profound　impacts　of　the　dynamics　of　labile　DOM　on　nutrient　cycling.　©　2016　Elsevier　Ltd