Department of Marine Science Safety and Environmental Protection, Massachusetts Maritime Academy, Buzzards Bay, USA
*通讯作者：William A Hubbard, Department of Marine Science Safety and Environmental Protection, Massachusetts Maritime Academy, Buzzards Bay, USA
Submission:July 02, 2020;Published:尤利10,2020
The black sea bassCentropristis striatapopulation of the Northwest Atlantic has been expanding over the past decade throughout its northern extent in Massachusetts waters. As abundance has increased in the coastal waters of Massachusetts, valuable commercial and recreational fisheries have developed. Relatively little is known about the habitat requirements for black sea bass at different life stages in Massachusetts waters. Identification and conservation of critical habitats is an essential component of sustainable fisheries management. In this study we conducted underwater video transects in Buzzards Bay, MA to better understand the habitats used by young-of-the-year black sea bass. We specifically focused on a comparison betweenCrepidula fornicatashell reefs and sandy/sponge habitats. Our results suggest that juvenile, young-of-the-year black sea bass are present in statistically significant higher densities on theCrepidula fornicata壳礁比沙质底栖栖息地。这种抽样在壳礁栖息地的壳体上鉴定了八倍的鱼类，将壳珊瑚礁视为马萨诸塞州水域的潜在苗圃栖息地。Crepidula reefs应考虑在马萨诸塞州海洋管理计划中作为特殊，敏感或独特资源的指定。
Climate mediated shifts in the ranges and distribution of fish populations pose important challenges for management and conservation. In the Northwest Atlantic, shifting species distributions have been documented for a suite of recreationally, commercially, and ecologically important finfish species . As species expand into areas previously unoccupied, it is imperative to understand how they are using habitats in these new areas and which habitats may require further protection to ensure sustainability and productivity of fish populations throughout their contemporary range.
Black sea bassCentropristis striataare distributed from Cape Cod, Massachusetts south to the Gulf of Mexico. Two distinct genetic stocks have been identified, delineating this population into a Northern and Southern stock, with Cape Hatteras, North Carolina serving as the breakpoint between the two [2,3]. Over the past few decades, the Northern black sea bass stock has undergone a rapid northward shift in its center of distribution [4,5]. Black sea bass is presently one of the largest recreational fisheries in the state of Massachusetts, with recreational anglers harvesting an estimated 743,617lb in 2017. Understanding how this burgeoning population is using different habitats at different life stages, in the coastal waters of Massachusetts, is imperative for conservation and sustainable management. In this paper, we focus on the habitat use of juvenile black sea bass in the northern extent of their range, Buzzards Bay, Massachusetts.
像许多的季节性迁徙物种inhabit the coastal waters of the northeastern United States, black sea bass occupy the inshore waters for the spring and summer months, and then migrate to deeper warmer waters to overwinter [5,6]. Spawning activity occurs annually from May through July, with the peak in June [7,8]. Once juveniles settle out of the pelagic stage and become demersal, cover and prey availability become limiting factors to their success . Young-of-the-year (YOY; age 0) utilize the shallow, nearshore habitats until their first offshore migration in the fall of the same year they were hatched. Structured habitats are favored over open sandy or muddy bottom . In addition, YOY exhibit site fidelity and territorial behaviors during their juvenile phase [11,12].
少年黑海低音众所周知，在岩石和壳体基材上觅食（图1）;青少年的主导猎物包括甲壳类动物和小鱼。Massachusetts北部Buzzards Bay的最近底栖研究已经确定了少年黑海低音和几个大的协会Crepidula fornicata(common slipper shell; hereafter,crepidula) shell reefs extending to over forty hectares (approximately one hundred acres) each . These shell reefs may be important forage and shelter areas that allow many valuable recreational finfish species to proliferate in Massachusetts. In Europe,crepidula被认为是侵入性的，从北美的牡蛎进口，并通过温暖的海水温度进行扩展。Crepidulaare native to Massachusetts waters, however, there is evidence that their abundance and distribution has increased in recent decades . Despite the prevalence of black sea bass in Massachusetts waters, relatively little is known about their habitat use at different life stages.
在这项研究中，我们寻求更好地了解不同栖息地的Yoy Black Sea Bass占用，以确定重要的苗圃栖息地，定义的苗圃栖息地，因为那些贡献了每单位成年人人群的平均个人数量的人数与其他少年栖息地相比，地区基础。我们使用水下视频横断面来量化两种不同的栖息地类型的黑海低音同yoy密度，结构化（Crepidula reef）和非结构化（桑迪底）。了解不同的栖息地如何为成年人口促进招聘是如何保护重要栖息地的重要性，而且还要提高我们根据最佳栖息地预测未来生产力和招聘能力的能力。
On 23 and 24 of August 2016, we conducted two sampling events using high definition (Sea viewer 6000) underwater video cameras to produce video recordings (Sea viewer HDMI H.264 Recorder) of aCrepidulareef(C-reef）和桑迪栖息地，具有粗糙的镗孔形态的形态Cliona celata。在上部秃鹰湾，主导基材是沙，沙子用海绵，壳珊瑚礁，宏观藻类床和淹没的水生植被。视频从配置文件视图中的表面部署的摄像头记录，并在后处理以产生屏幕截图，用于记录和量化少年黑海低音密度。两个采样站分开了2.5公里，位于猪岛渠道的末端（东部）Buzzards Bay中，沿着外滩堤防（图2）。C-Reef视频是41ᵒ40'28.82“N /70ᵒ40'20.35”W的一般附近，而沙子/海绵视频是41ᵒ40'56.93“N /-70ᵒ42'3.26”的一般附近。在深度为5米和六米之间的两个采样位置完成视频横断面。我们从视频横断面数据获得了屏幕截图（图3）。所有屏幕截图都在全屏中进行了审查，八个缩放象限，然后通过增强的对比/颜色缩放。保留了至少90％的图像，适用于检查的视野。分析。在水中取出的屏幕射击过于混浊以进行检查，或者通常具有差的质量。
Figure 2:地图显示了MA的Buzzards Bay中每个栖息地类型的视频横断面的位置。
Figure 3:砂/海绵(A)和C-reef壳(B)栖息地的小石子n shots from Buzzards Bay video transects.
三十三个屏幕截图C-reefand 61 from the sand/sponge habitat were examined in detail, and numbers of Young-of-the-Year (YOY) black sea bass were recorded for each screen shot. The mean fish density from the video transect observations was 6.30 fish/m2(Sd=4.16) in theC-reef栖息地和0.71鱼/ m2(Sd=0.82) in the sand/sponge habitat. The lack of overlap between the distributions of bootstrapped mean fish density estimates, by habitat, provides strong evidence of a significant difference in fish density between the two habitats (Figure 4). In addition, there were no bootstrap t-values that were greater than or equal to the Student’s t-statistic (t=7.65); further supporting a rejection of the null hypothesis that fish density in the two habitat types is equal (p≈0). The C-reef habitat supported eight times the density of fish observed in the sandy bottom habitat in our study area.
Figure 4:通过栖息地类型的自动分布平均鱼密度估计（鱼/ M2）。
TheC-reefslipper shell residents produce a nutrient rich waste that settles in among the stacked shell “curls”. This rich substrate is the result of the water filtration provided byCrepidula fornicata，一种独特的生物，因为它是过滤器进料美食。场和实验室观察表明过滤和转化为细有机物是多产性的。许多螃蟹和两栖群与这种壳栖息地的底栖群体有关。小圆形polychaete Polygordius apendiculatacan also be a significant forage component of someC-reef栖息地。Polygordiushas reached densities of over 10,000 organisms per square meter (up to 11700/m2) on some reefs sampled for benthic community composition ; (Figure 5). Other smallpolychaetes,gastropodsandAmphipods.colonize the interstitial shell spaces providing a diverse symbiotic community. This diverse benthic community provides a significant forage base for juvenile black sea bass and other species . Our results suggest thatC-reefhabitat could be important nursery habitat for YOY juvenile black sea bass, contributing far greater numbers per-unit-area than the sandy/sponge habitats.  have proposed that it is not just the per-unit-area contributions that should define nursery habitats, but the overall contributions of habitat.
If we make a broad assumption that the field-of-view of each high definition video frame is one square meter, we can allocate theC-reefs每平方米托管6.3少年黑鲈鱼。这并不是推断这是这两个栖息地的可量化承载能力关系，只是对壳与沙子/海绵栖息地的黑海低音偏好的指示。Buzzards Bay的Benthic映射的2017年报告确定了七个密集区域C-reefhabitat in the upper Bay. One is as large as 53 hectares and several more are over 40 hectares. Therefore, a minimum of 700 acres (2.833km2) were documented in the study area; an area predicted to host over seventeen million (17,847,900) YOY. In 2014, the United States Geologic Survey (USGS) conducted a hydroacoustic survey Buzzards Bay which effectively mapped “Shell Zones” .
Figure 5:Still screen shot from video transect showing the small surficial polychaete Polygordius apendiculata, which is a significant forage component for black sea bass in the C-reef habitat.
Shell Zones are areas of high densitycrepidulabeds, identified by high acoustic backscatter in areas of fine-grained surficial sediments, and verified using digital photographs. The Shell Zones identified cover 14.8 km2, which is 2% of the Buzzards Bay sea floor by area; this area is likely larger but has yet to be verified with photographs of the bottom habitat . Assuming if the density we observed in theC-reef栖息地是较大的海湾代表，我们估计这一栖息地可以支持大约93,240,000同比黑鲈鱼。
巴泽兹湾是一个动态的生态系统,fluctuated dramatically through time. The contemporary habitats observed throughout the bay have changed considerably from the habitats in the region 50 years ago. In 1955 a benthic infaunal survey of Buzzards Bay was conducted  and was then repeated in 2011 and 2012 . The comparison between the two time periods showed a shift towards higher nutrient concentrations, warmer temperatures, reduction in species diversity, and a restructuring of the benthic community. One of the marked shifts in benthic species composition was the proliferation ofcrepidulabeds.Crepidula从1955年的样品中缺席，但在2011/2012年的两个地点展示了占主导地位。另外，存在cprepidulain the Massachusetts Division of Marine Fisheries’ inshore trawl survey , a synoptic trawl survey that has sampled the coastal waters of Massachusetts twice per year (May and September) since 1978, has generally increased through time (Figure 6).
Figure 6:Average liters per tow of Crepidula fornicata in the Massachusetts Division of Marine Fisheries inshore trawl survey, from 1983-2017. The gray line represents a loess curve through the data points with the 95% confidence interval depicted by the light gray shaded area.
建议气候变化和人为投入作为潜在的司机，促进了促进巨额C-reefhabitat in Buzzards Bay . Likewise, warming water temperatures has been suggested as an important driving force in the expansion of the black sea bass population into Massachusetts waters . Black sea bass are a prized game fish so as their distribution has shifted north, important recreational and commercial fisheries have developed in the region. The recreational harvest of adult black sea bass averaged 352,443 fish per year during the decade from 2006 to 2017, state-wide in Massachusetts . Adapting to climate change requires an understanding of how different habitats are used at different life stages for a wide range of species. Our results suggest thatC-reef栖息地在每单位面积上大量贡献成年黑海低音人群。这些结果与USGS映射努力相结合，建议C-reefis also a large component of the overall bottom habitat in Buzzards Bay; therefore, supporting the classification as important nursery habitat. The tremendous ecological productivity of the Massachusettscrepidulashell reef habitat should be protected. The reliance of important fishery resources on this benthic structure, such as the black sea bass juvenile phase, warrants evaluation as a Special, Sensitive, or Unique (SSU) resource in the Massachusetts Coastal Zone Ocean Management Plan.
This research was supported by the Massachusetts Environmental Trust (https://www.mass.gov/environmentallicense- plates) Coastal America Foundation (www. CoastalAmericaFoundation.org).
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