Quantification of Nursery Habitats for Blue Crabs in Chesapeake Bay
Quantification of Nursery Habitats for Blue Crabs in Chesapeake Bay
复制标题
切萨皮克湾蓝蟹栖息地的量化
DOI：
10.25773/v5-237q-gc83
复制
发表时间：
2014
影响因子：
1.4
通讯作者：
Gina M. Ralph
中科院分区：
文献类型：
--
作者：
Gina M. Ralph
蓝蟹是切萨皮克湾的标志性物种，支持重要的商业和休闲渔业，并作为食物网的关键环节发挥作用。结构复杂的生境往往被认为是蓝蟹和其他具有重要商业价值的鱼类和甲壳类物种的苗圃，因为它能促进幼蟹的生长和生存。我通过实地研究和人口模型量化了浅水栖息地作为蓝蟹苗圃的价值。在第二章中，我利用了一个为期两年的幼蟹调查，在下湾的植被栖息地，研究栖息地的复杂性对幼蟹密度的影响。海草覆盖和青少年密度之间的函数关系是指数，这样，有更多的螃蟹每单位的增加，在覆盖率高的植被栖息地比在低覆盖率。这种关系在空间上有所不同，东海岸的密度较高，两年之间的密度也较高。高的空间和年度变化导致的问题，如何在整个招聘季节的栖息地利用变化。在第3章中，我通过对约克河浅水栖息地进行高时空分辨率的调查，讨论了栖息地之间的补充和迁移时间。这项研究提供了证据，幼年蓝蟹在植被生境中的承载能力在10-15蟹m2.1发现，小青少年在浅无植被生境的密度大大高于以前的记录，这表明，目前的模式蓝蟹招聘需要修改，包括浅无植被生境的小青少年的重要性。在第4章中，我研究了作为年龄或个体发育的函数的栖息地利用模式对蓝蟹种群评估的影响，通过比较幼蟹密度和丰度的估计，从浅植被和无植被的栖息地，估计从深栖息地采样的初步调查的股票评估。尽管面积相对较小，但两个浅水生境中的幼蟹丰度非常高，因此表明冬季疏浚调查大大低估了幼蟹的丰度。如果这种偏差在年度间不一致，可能是温度的函数，那么种群评估可能会产生有偏差的参考点。最后，我在第5章中开发了一个探索性的特定生境人口模型，以量化生境对人口适合度的影响。在所有的捕捞死亡率，包括一个完整的休渔期，人口增长率小于1时，只有无植被的栖息地是本; 0岁螃蟹的生存增加提供了植被的栖息地，导致人口增长率的增加。植被生境提供了一个缓冲区，从捕捞死亡率，也就是说，作为青少年的生存在植被生境增加，人口可以维持较高的捕捞死亡率，同时仍然保持稳定，甚至增加。浅植被栖息地显着影响青少年蓝蟹和整体人口增长率。至关重要的是，这些栖息地被认为是在未来的探索的动态蓝蟹，以及其他物种表现出个体发育的变化，在栖息地的利用。这篇论文的章节是以科学出版的手稿格式写的。因此，每一章都是以第三人称写的，以代表我的合著者，并且格式与手稿已经或将要提交的出版物的指导方针保持一致。在撰写本文时，各章的引文如下：第2章拉尔夫，G.M.，塞茨，R. D.，Orth，R.J.，克尼克，K.E.，和Lipcius，R.N. 2013.在切萨皮克湾海草覆盖和青少年蓝蟹密度之间的大规模关联。海洋生态学进展系列，488：51-63。[贡献号3278弗吉尼亚海洋科学研究所，威廉和玛丽学院，格洛斯特点，弗吉尼亚州23062]第3章拉尔夫，G.M.，Seebo，M.S.，和Lipcius，R.N.青少年蓝蟹补充到海草和无植被苗圃栖息地的时空模式。第四章拉尔夫，G.M.，和Lipcius，R.N.接纳的话关键生境和资源评估：切萨皮克湾蓝蟹种群调查中的年龄特异性偏差。美国渔业协会会刊。第五章拉尔夫，G.M.，米勒，T. J.，和Lipcius，R.N.在准备。量化的作用苗圃栖息地的切萨皮克湾蓝蟹使用人口健身。切萨皮克湾蓝蟹育苗数量的定量分析第一章切萨皮克湾蓝蟹：生活史和栖息地利用
The blue crab is an iconic species in Chesapeake Bay, supporting important commercial and recreational fisheries and functioning as a critical link in the food web. Structurally complex habitats are often cited as nurseries for the blue crab, and other commercially important fish and crustacean species, by providing enhanced growth and survival for juveniles. I quantified the value of shallow habitats as nurseries for blue crabs through field studies and a demographic model. In Chapter 2 ,1 utilized a two-year juvenile survey in vegetated habitats of the lower Bay to examine the effect of habitat complexity on the density of juvenile blue crabs. The functional relationship between seagrass cover and juvenile density was exponential, such that there were proportionally more crabs per unit increase in cover of vegetated habitat at high percent cover than at low percent cover. The relationship varied spatially, with higher densities on the eastern shore, and between the two years. The high spatial and annual variability led to questions about how habitat utilization varied throughout the recruitment season. I addressed the timing of recruitment and migration between habitats in Chapter 3 through the development of a survey of shallow habitats in the York River with high temporal and spatial resolution. The study provided evidence for a carrying capacity of juvenile blue crabs in vegetated habitats at 10-15 crabs m2.1 found substantially higher densities of small juveniles in shallow unvegetated habitats than previously documented, which suggested that the current paradigm for blue crab recruitment requires modification to include the importance of shallow unvegetated habitats for small juveniles. In Chapter 4, I examined the effect of habitat utilization patterns as a function of age or ontogeny on the blue crab stock assessment by comparing juvenile density and abundance estimates from shallow vegetated and unvegetated habitats to estimates from deep habitats sampled by the primary survey for the stock assessment. Juvenile abundance was very high in both shallow habitats despite the relatively smaller area, thus suggesting that the winter dredge survey substantially underestimated the abundance of juvenile crabs. If this bias is inconsistent inter-annually, potentially as a function of temperature, then stock assessments may be producing biased reference points. Finally, I developed an exploratory habitat-specific demographic model to quantify the effects of habitat on population fitness in Chapter 5. Under all fishing mortality rates, including a complete fishing moratorium, the population growth rate was less than 1 when only unvegetated habitat was present; the increased survival of age-0 crabs provided by vegetated habitats led to increases in the population growth rates. The vegetated habitats provided a buffer from fishing mortality; that is, as the survival of juveniles increased in vegetated habitats, the population could sustain higher fishing mortality rates while still remaining stable or even increasing. Shallow vegetated habitats substantially influence juvenile blue crabs and the overall population growth rate. It is essential that these habitats be considered in future explorations of the dynamics of blue crabs, as well as other species that exhibit ontogenetic shifts in habitat utilization. AUTHOR’S NOTE The chapters of this dissertation were written in manuscript format for scientific publication. Thus, each chapter is written in the third person to represent my co-authors, and is formatted to align with the guidelines of the publication to which the manuscript was or will be submitted. At the time of writing, citations for individual chapters are as follows: CHAPTER 2 Ralph, G.M., Seitz, R.D., Orth, R.J., Knick, K.E., and Lipcius, R.N. 2013. Broad-scale association between seagrass cover and juvenile blue crab density in Chesapeake Bay. Marine Ecology Progress Series, 488:51-63. [Contribution number 3278 of the Virginia Institute of Marine Science, The College of William and Mary, Gloucester Point, VA 23062] CHAPTER 3 Ralph, G.M., Seebo, M.S., and Lipcius, R.N. In prep. Spatiotemporal patterns in juvenile blue crab recruitment to seagrass and unvegetated nursery habitats. CHAPTER 4 Ralph, G.M., and Lipcius, R.N. Accepted. Critical habitats and stock assessment: agespecific bias in the Chesapeake Bay blue crab population survey. Transactions of the American Fisheries Society. CHAPTER 5 Ralph, G.M., Miller, T.J., and Lipcius, R.N. In prep. Quantifying the role of nursery habitats for the Chesapeake Bay blue crab using population fitness. Quantification of Nursery Habitats for Blue Crabs in Chesapeake Bay CHAPTER 1 The Chesapeake Bay Blue Crab: Life History and Habitat Utilization