Cawthron Institute, 98 Halifax Street East, 7010, Nelson, New Zealand; Department of Biochemistry Te Tari Matū Koiora, University of Otago, Dunedin, Aotearoa New Zealand.
Cawthron Institute, 98 Halifax Street East, 7010, Nelson, New Zealand.
Harmful Algae. 2023 Aug;127:102465. doi: 10.1016/j.hal.2023.102465. Epub 2023 Jun 15.
The green-lipped mussel (GLM) Perna canaliculus is an economically, ecologically, and culturally important species in Aotearoa New Zealand. Since 2011, harmful algal blooms (HABs) of Alexandrium spp. have occurred annually in the Marlborough Sounds, the largest GLM aquaculture region in New Zealand. Across a similar timeframe, there has been a severe reduction in wild spat (juvenile mussel) catch. This research investigated the effects of Alexandrium pacificum (which produces paralytic shellfish toxins; PSTs) and A. minutum (a non-producer of PSTs) on the development of four GLM larval life stages (gametes, embryos, D-stage and settlement). Early life stages of GLM were exposed to environmentally relevant concentrations of Alexandrium spp. as whole cell, lysate and filtrate treatments. A 48-h exposure of embryos to whole A. pacificum cells at 500 cells mL caused lysis of embryos, severe abnormalities, and reduced development through to veliger (D-stage) larvae by 85%. GLM growth was impaired at cell concentrations as low as 250 cells mL during a 4-day exposure of D-stage larvae to both Alexandrium spp. Exposure of GLM to both whole and lysed treatments of Alexandrium spp. at 500 cells mL resulted in halved larval growth rates (2.00 µm day vs 4.48 µm day in the control) and growth remained impeded during a 4-day recovery period. Both A. pacificum and A. minutum were found to negatively impact D-larvae. Both whole-cell and lysed-cell treatments of A. pacificum had similar negative effects, suggesting that Alexandrium spp. toxicity to D-larvae is independent of PSTs. Additionally, cell membrane-free treatments of A. pacificum had no negative effects on embryo development, indicating that cell surface-associated bioactive compounds may be responsible for the observed negative effects during this early life stage. Conversely, non-PST-producing A. minutum was toxic to D-stage larvae but not to embryos; larval growth was reduced following a brief 1 h exposure of sperm to cell membrane-free treatments of A. pacificum. No effects were recorded in GLM larvae exposed during settlement, highlighting the potential for differences in susceptibility of early life stages to Alexandrium spp. exposure and the influence of exposure durations. In the wild, blooms of Alexandrium spp. can persist for several months, reaching cell densities higher than those investigated in the present study, and as such may be detrimental to the vulnerable early life stages of GLM.
新西兰的绿唇贻贝（GLM）Perna canaliculus 是一种具有经济、生态和文化重要性的物种。自 2011 年以来，亚历山大藻属（Alexandrium spp.）有害赤潮（HABs）每年都在马尔堡峡湾（新西兰最大的 GLM 水产养殖区）发生。在类似的时间内，野生幼贝（贻贝幼体）的捕获量严重减少。这项研究调查了亚历山大太平洋藻（产生麻痹性贝类毒素；PSTs）和亚历山大微小藻（不产生 PSTs）对 GLM 幼虫四个生命阶段（配子、胚胎、D 期和附着）发育的影响。GLM 的早期生命阶段暴露于环境相关浓度的亚历山大藻属作为全细胞、裂解物和滤液处理。胚胎在 500 个细胞 mL 的全 A. pacificum 细胞中暴露 48 小时导致胚胎裂解、严重畸形，并将发育减少到 85%的翼足幼虫（D 期）。GLM 的生长在 D 期幼虫暴露于亚历山大藻属的 4 天期间，即使在低至 250 个细胞 mL 的细胞浓度下也受到损害。暴露于 500 个细胞 mL 的全细胞和裂解物处理的 GLM，其幼虫生长速度减半（对照组为 4.48 µm 天，实验组为 2.00 µm 天），并且在 4 天的恢复期内生长仍然受到阻碍。发现 A. pacificum 和 A. minutum 都对 D 幼虫产生负面影响。A. pacificum 的全细胞和裂解细胞处理均具有相似的负面影响，表明亚历山大藻属对 D 幼虫的毒性不依赖于 PSTs。此外，无细胞膜的 A. pacificum 处理对胚胎发育没有负面影响，表明在这个早期生命阶段，与细胞膜相关的生物活性化合物可能是导致观察到的负面影响的原因。相反，非 PST 产生的 A. minutum 对 D 期幼虫有毒，但对胚胎无毒；精子暴露于无细胞膜的 A. pacificum 处理 1 小时后，幼虫生长受到抑制。在附着期间暴露的 GLM 幼虫没有记录到任何影响，这突出表明早期生命阶段对亚历山大藻属暴露的敏感性差异以及暴露持续时间的影响。在野外，亚历山大藻属的水华可能持续数月，达到比本研究中更高的细胞密度，因此可能对 GLM 脆弱的早期生命阶段有害。
