草鱼不同混养模式下围隔底泥反硝化、硝化和氨化速率

应用乙炔抑制法测定了草鱼(Ctenopharyngodon idellus)不同混养模式围隔底泥的硝化、反硝化和氨化速率,以探究草鱼不同混养模式对池塘底泥－水界面N元素动态变化的影响,并为草鱼养殖模式的优化提供必要的参考依据.混养组合分别为一元组（草鱼）、二元组（草鱼+鲢、草鱼+凡纳滨对虾）、三元组（草鱼+鲢+凡纳滨对虾,设2种放养比例）.结果显示:1）草鱼不同混养模式中底泥的反硝化速率范围为0～734.15 μmol/(m2·d),硝化速范围为0～1 209.20 mmol/(m2·d),化速率范围为0～41.25 mmol/(m2·d).2)草鱼不同混养模式底泥的反硝化速率较高,与很多河口和湖泊数值接近；在养殖中期,底泥的硝化速率很小甚至检测不到；底泥的氨化速率呈逐月递增趋势,以三元混养组最高.3）混养组中凡纳滨对虾(Litopenaeus vannamei)的放养密度越大,草鱼的放养密度越小,反硝化作用出现得越早,但反硝化速率很难保持开始的水平；反之,反硝化作用出现得较晚,并会随着养殖周期的推移迅速升高；放养种类越单一,底泥的硝化速率越低,且鲢(Hypophthalmichthys molitrix)放养密度越高,硝化速率越高.从养殖模式优化的角度来看,草鱼三元混养组要优于单养和二元混养组,但三元混养组中两种放养密度各有优劣,有待进一步优化以确定最佳放养比例.

Benthic denitrification, nitrification, and nitrate reduction rates in a range of grass carp polyculture enclosures

AIT(acetyleneinhibition).Theratesofdenitrification,nitrification,andammonificationrangedfrom0−734.15)22estuariesandpools.Thenitrificationrateswereeitherveryloworundetectableduringthemid-periodofculture.Theammonificationratesincreasedeachmonthinallsystems,butwerehighestinthetriplepolyculturesystem.Ahigherratioofshrimp)tograsscarpwasassociatedwithanearlierincreaseindenitrification.However,thesystemwasunabletomaintainthislevelofnitrification.Conversely,ahigherabundanceofgrasscarpresultedinadelayedincreaseindenitrification,butamorerapid,andsustainedincreaseduringthecultureperiod.Ingeneral,cultureswithfewerspecieshadlowerratesofnitrificationandcultureswithahigherproportionofsilvercarp)hadhigherratesofnitrification.Thepolyculturegroupthemonoculturetriplegroupandthebinarygroups(grasscarpandshrimporgrasscarpandsilvercarpWetestedtwostockingdensitiesofthepolyculturegroup,butitisunclearwhichofthesegroupsperformedbest.TheobjectiveofthepresentstudyistoaccesstheeffectsofdifferentpolyculturesystemsofgrasscarponthedynamicchangesofNatthepondssediment-waterinterface,andtoprovideacertainbasisforthefurther.