Dinoflagellate　blooms　have　negative　adverse　effects　on　marine　ecosystems.　However,　our　knowledge　about　the　spatiotemporal　distribution　of　dinoflagellate　communities　and　their　correlations　with　micro-eukaryotic　and　bacterial　communities　is　still　rare.　Here,　the　sediment　micro-eukaryotic　and　bacterial　communities　were　explored　in　the　Taiwan　Strait　(TWS)　by　16S　and　18S　rRNA　gene　high-throughput　sequencing.　We　found　that　the　dinoflagellates　were　the　most　abundant　algal　group　in　TWS,　and　their　relative　abundance　was　higher　in　spring　and　autumn　than　in　summer.　Moreover,　the　species　richness　and　community　composition　of　dinoflagellates　showed　strong　seasonal　patterns.　NO3-N　and　NH4-N　had　the　strongest　correlations　with　the　spatiotemporal　dynamics　of　community　composition　of　dinoflagellates.　The　dinoflagellates　had　a　significantly　wider　niche　breadth　than　other　algal　groups　for　NH4-N,　NO3-N　and　NO2-N,　and　therefore　potentially　contributed　to　a　wider　distribution　range　and　high　abundance　in　TWS.　In　addition,　the　dinoflagellates　had　stronger　impacts　on　microeukaryotes　than　on　bacteria　for　both　community　composition　and　species　richness.　However,　the　dinoflagellates　showed　close　coexistence　with　bacteria　but　loose　coexistence　with　microeukaryotes　in　spring　co-occurrence　networks.　This　close　coexistence　suggests　the　potentially　strong　synergy　effects　between　dinoflagellates　and　bacteria　in　spring　dinoflagellate　blooms　in　TWS.　Overall,　this　study　revealed　the　distribution　mechanisms　of　dinoflagellates　in　TWS　based　on　niche　breadth　and　also　unveiled　the　different　effects　of　dinoflagellates　on　micro-eukaryotic　and　bacterial　communities.