Taylor David L, McNamee Jason, Lake John, Gervasi Carissa L, Palance Danial G
Roger Williams University, Department of Marine Biology, One Old Ferry Road, Bristol, RI 02809, USA.
Division of Fish and Wildlife, Marine Fisheries, Fort Wetherill Marine Laboratory, 3 Fort Wetherill Drive, Jamestown, RI 02835.
Estuaries Coast. 2016 Sep;39(5):1505-1525. doi: 10.1007/s12237-016-0089-x. Epub 2016 Mar 22.
This study evaluated the relative importance of the N arragansett Bay estuary (RI and MA, USA), and associated tidal rivers and coastal lagoons, as nurseries for juvenile winter flounder, , and summer flounder, . Winter flounder (WF) and summer flounder (SF) abundance and growth were measured from May to October (2009-2013) and served as indicators for the use and quality of shallow-water habitats (water depth < 1.5-3.0 m). These bioindicators were then analyzed with respect to physiochemical conditions to determine the mechanisms underlying intra-specific habitat selection. WF and SF abundances were greatest in late May and June (maximum monthly mean = 4.9 and 0.55 flounder/m for WF and SF, respectively), and were significantly higher in the tidal rivers relative to the bay and lagoons. Habitat-related patterns in WF and SF abundance were primarily governed by their preferences for oligohaline (0.1-5 ppt) and mesohaline (6-18 ppt) waters, but also their respective avoidance of hypoxic conditions (< 4 mg DO/L) and warm water temperatures (> 25 °C). Flounder habitat usage was also positively related to sediment organic content, which may be due to these substrates having sufficiently high prey densities. WF growth rates (mean = 0.25 ± 0.14 mm/d) were negatively correlated with the abundance of conspecifics, whereas SF growth (mean = 1.39 ± 0.46 mm/d) was positively related to temperature and salinity. Also, contrary to expectations, flounder occupied habitats that offered no ostensible advantage in intra-specific growth rates. WF and SF exposed to low salinities in certain rivers likely experienced increased osmoregulatory costs, thereby reducing energy for somatic growth. Low-salinity habitats, however, may benefit flounder by providing refugia from predation or reduced competition with other estuarine fishes and macro-invertebrates. Examining WF and SF abundance and growth across each species' broader geographic distribution revealed that southern New England habitats may constitute functionally significant nurseries. These results also indicated that juvenile SF have a geographic range extending further north than previously recognized.
本研究评估了美国罗德岛州和马萨诸塞州的纳拉甘西特湾河口以及相关的潮汐河流和沿海泻湖作为冬比目鱼和夏比目鱼幼鱼育幼场的相对重要性。在2009年至2013年的5月至10月期间测量了冬比目鱼（WF）和夏比目鱼（SF）的丰度和生长情况，并将其作为浅水栖息地（水深<1.5 - 3.0米）利用情况和质量的指标。然后根据理化条件对这些生物指标进行分析，以确定种内栖息地选择的潜在机制。WF和SF的丰度在5月下旬和6月最高（WF和SF的月平均最大值分别为4.9条比目鱼/平方米和0.55条比目鱼/平方米），并且潮汐河流中的丰度相对于海湾和泻湖显著更高。WF和SF丰度与栖息地相关的模式主要受它们对低盐度（0.1 - 5 ppt）和中盐度（6 - 18 ppt）水域的偏好支配，但也受它们各自对缺氧条件（<4毫克溶解氧/升）和温暖水温（>25°C）的回避影响。比目鱼的栖息地利用还与沉积物有机含量呈正相关，这可能是由于这些基质具有足够高的猎物密度。WF的生长率（平均 = 0.25 ± 0.14毫米/天）与同种个体的丰度呈负相关，而SF的生长（平均 = 1.39 ± 0.46毫米/天）与温度和盐度呈正相关。此外，与预期相反，比目鱼占据的栖息地在种内生长率方面没有明显优势。在某些河流中暴露于低盐度的WF和SF可能经历了更高的渗透调节成本，从而减少了用于体细胞生长的能量。然而，低盐度栖息地可能通过提供躲避捕食的场所或减少与其他河口鱼类和大型无脊椎动物的竞争而使比目鱼受益。研究每个物种更广泛地理分布范围内的WF和SF丰度及生长情况表明，新英格兰南部的栖息地可能构成功能上重要的育幼场。这些结果还表明，幼年SF的地理分布范围比之前认为的向北延伸得更远。
