Virginia Institute of Marine Science, William & Mary, Gloucester Point, Virginia, United States of America.
PLoS One. 2019 Nov 5;14(11):e0224770. doi: 10.1371/journal.pone.0224770. eCollection 2019.
In estuaries, salinity is believed to limit the colonization of brackish water habitats by freshwater species. Blue catfish Ictalurus furcatus, recognized as a freshwater species, is an invasive species in tidal rivers of the Chesapeake Bay. Salinity tolerance of this species, though likely to determine its potential range expansion and dispersal in estuarine habitats, is not well-known. To address this issue, we subjected blue catfish to a short-term salinity tolerance experiment and found that this species tolerates salinities higher than most freshwater fishes and that larger blue catfish tolerate elevated salinities for longer periods compared with smaller individuals. Our results are supported by spatially extensive, long-term fisheries surveys in the Chesapeake Bay region, which revealed a gradual (1975-2017) down-estuary range expansion of blue catfish from tidal freshwater areas to habitats exceeding 10 psu [practical salinity units] and that large blue catfish (> 200 mm fork length) occur in salinities greater than 10 psu in Chesapeake Bay tributaries. Habitat suitability predictions based on our laboratory results indicate that blue catfish can use brackish habitats to colonize new river systems, particularly during wet months when salinity decreases throughout the tidal rivers of the Chesapeake Bay.
在河口，盐度被认为会限制淡水物种在咸淡水生境中的定殖。蓝鲶 Ictalurus furcatus 被认为是一种淡水物种，却是切萨皮克湾潮汐河流中的入侵物种。尽管该物种对盐度的耐受性可能决定其在河口栖息地的潜在扩张和扩散，但这方面的了解并不充分。为了解决这个问题，我们对蓝鲶进行了短期耐盐性实验，发现该物种能够耐受高于大多数淡水鱼类的盐度，并且较大的蓝鲶比小个体能够耐受更高的盐度更长时间。我们的研究结果得到了切萨皮克湾地区广泛的长期渔业调查的支持，这些调查显示，自 1975 年至 2017 年，蓝鲶从潮汐淡水区逐渐向下游扩展到盐度超过 10 个实用盐度单位的栖息地，并且在切萨皮克湾支流中，大蓝鲶（> 200 毫米叉长）的出现盐度大于 10 个实用盐度单位。基于实验室结果的栖息地适宜性预测表明，蓝鲶可以利用咸淡水生境来殖民新的河流系统，特别是在盐分随潮汐河流下降的潮湿月份。
