Hardy Sarah M, Smith Craig R, Thurnherr Andreas M
School of Fisheries and Ocean Sciences, University of Alaska, Fairbanks, PO Box 757220, Fairbanks, AK 99775, USA
Department of Oceanography, University of Hawaii, Manoa, 1000 Pope Road, Honolulu, HI 96822, USA.
Proc Biol Sci. 2015 Jun 7;282(1808):20150193. doi: 10.1098/rspb.2015.0193.
Low food availability is a major structuring force in deep-sea benthic communities, sustaining only very low densities of organisms in parts of the abyss. These low population densities may result in an Allee effect, whereby local reproductive success is inhibited, and populations are maintained by larval dispersal from bathyal slopes. This slope-abyss source-sink (SASS) hypothesis suggests that the abyssal seafloor constitutes a vast sink habitat with macrofaunal populations sustained only by an influx of larval 'refugees' from source areas on continental slopes, where higher productivity sustains greater population densities. Abyssal macrofaunal population densities would thus be directly related to larval inputs from bathyal source populations. We evaluate three predictions derived from the SASS hypothesis: (i) slope-derived larvae can be passively transported to central abyssal regions within a single larval period, (ii) projected larval export from slopes to the abyss reproduces global patterns of macrofaunal abundance and (iii) macrofaunal abundance decreases with distance from the continental slope. We find that abyssal macrofaunal populations are unlikely to be sustained solely through influx of larvae from slope sources. Rather, local reproduction probably sustains macrofaunal populations in relatively high-productivity abyssal areas, which must also be considered as potential larval source areas for more food-poor abyssal regions.
食物可利用性低是深海底栖生物群落的主要构建力量，在部分深渊区域仅维持极低的生物密度。这些低种群密度可能导致阿利效应，即局部繁殖成功率受到抑制，种群靠来自半深海斜坡的幼体扩散来维持。这种斜坡-深渊源汇（SASS）假说表明，深渊海底构成一个巨大的汇生境，大型底栖动物种群仅靠来自大陆斜坡源区的幼体“难民”流入来维持，在大陆斜坡源区较高的生产力维持着更大的种群密度。因此，深渊大型底栖动物的种群密度将与来自半深海源种群的幼体输入直接相关。我们评估了从SASS假说得出的三个预测：（i）来自斜坡的幼体能够在单个幼体期内被动运输到深渊中部区域，（ii）预计从斜坡到深渊的幼体输出反映了大型底栖动物丰度的全球模式，以及（iii）大型底栖动物的丰度随着与大陆斜坡距离的增加而降低。我们发现，深渊大型底栖动物种群不太可能仅通过来自斜坡源的幼体流入来维持。相反，局部繁殖可能维持了生产力相对较高的深渊区域的大型底栖动物种群，这些区域也必须被视为食物匮乏的深渊区域潜在的幼体源区。
