School of Marine Sciences, University of Maine, Orono, ME, USA.
Glob Chang Biol. 2019 Nov;25(11):3906-3917. doi: 10.1111/gcb.14778. Epub 2019 Aug 28.
Ocean warming can drive poleward shifts of commercially important species with potentially significant economic impacts. Nowhere are those impacts greater than in the Gulf of Maine where North America's most valuable marine species, the American lobster (Homarus americanus Milne Edwards), has thrived for decades. However, there are growing concerns that regional maritime economies will suffer as monitored shallow water young-of-year lobsters decline and landings shift to the northeast. We examine how the interplay of ocean warming, tidal mixing, and larval behavior results in a brighter side of climate change. Since the 1980s lobster stocks have increased fivefold. We suggest that this increase resulted from a complex interplay between lobster larvae settlement behavior, climate change, and local oceanographic conditions. Specifically, postlarval sounding behavior is confined to a thermal envelope above 12°C and below 20°C. Summer thermally stratified surface waters in southwestern regions have historically been well within the settlement thermal envelope. Although surface layers are warming fastest in this region, the steep depth-wise temperature gradient caused thermally suitable areas for larval settlement to expand only modestly. This contrasts with the northeast where strong tidal mixing prevents thermal stratification and recent ocean warming has made an expansive area of seabed more favorable for larval settlement. Recent declines in lobster settlement densities observed at shallow monitoring sites correlate with the expanded area of thermally suitable habitat associated with warmer summers. This leads us to hypothesize that the expanded area of suitable habitat may help explain strong lobster population increases in this region over the last decade and offset potential future declines. It also suggests that the fate of fisheries in a changing climate requires understanding local interaction between life stage-specific biological thresholds and finer scale oceanographic processes.
海洋变暖可能导致具有重要商业价值的物种向极地迁移，从而带来潜在的重大经济影响。在缅因湾，这些影响最为显著，因为北美最有价值的海洋物种——美洲螯龙虾（Homarus americanus Milne Edwards）已经繁荣了几十年。然而，人们越来越担心，随着监测到的浅水区幼龙虾数量减少，以及龙虾捕捞地向东北转移，该地区的海洋经济将会受到影响。我们研究了海洋变暖、潮汐混合和幼虫行为如何相互作用，从而带来了气候变化的积极影响。自 20 世纪 80 年代以来，龙虾的数量增加了五倍。我们认为，这种增长是由龙虾幼虫定居行为、气候变化和当地海洋条件之间的复杂相互作用所导致的。具体来说，幼龙虾的发声行为局限于 12°C 至 20°C 之间的热环境中。西南地区夏季的热力分层表层水在历史上一直处于适合定居的热环境中。尽管该地区的表层水升温最快，但陡峭的垂直温度梯度使得适合幼虫定居的区域仅略有扩大。这与东北部形成了鲜明对比，在东北部，强劲的潮汐混合阻止了热力分层，而最近的海洋变暖使得更广阔的海底区域对幼虫定居更为有利。在浅海监测点观察到的龙虾幼虫定居密度最近有所下降，这与与夏季变暖相关的更广泛的适宜栖息地面积扩大有关。这使我们假设，适宜栖息地面积的扩大可能有助于解释过去十年该地区龙虾数量的强劲增长，并抵消未来潜在的下降。这也表明，在气候变化的背景下，渔业的命运需要理解特定生命阶段的生物阈值与更精细的海洋过程之间的局部相互作用。
