Application of paleoenvironmental approaches provides insight into the magnitude and timing of responses to climate warming in aquatic-ecosystems of northern Canada. We examined subfossil biological (Diptera:Chironomidae) and geochemical indicators (organic carbon and elemental nitrogen and stable isotope composition) in a sediment core from Buckland Lake, northern Manitoba, to assess the influence of recent warming (1981–2011) in the central subarctic region of Canada. The earlier part of the paleolimnological record (1830–1980) was characterized by relatively low chironomid diversity (N2 ~ 6), consisting primarily of profundal taxa (Orthocladius consobrinus and Chironomus), low organic matter content of sediments (< 12%), low C:N ratios (< 9), and high δ¹⁵N values (> 3‰), indicative of a cold-water environment with low nitrogen demand. Between 1910 and 1980, there was a decline in profundal taxa, with small gradual increases in littoral taxa, such as Cladotanytarsus mancus-group. Post-1980 sediment core intervals had distinct geochemistry, with declines in δ¹³C_org from − 27.5‰ to almost − 29‰, consistent with warming, increased terrestrial influence, and increased snowfall and runoff. We found substantial inferred warming (+ 1–2 °C), with several chironomid-inferred temperatures nearly 3 °C warmer than typical pre-1980 inferences. Concurrently, several warm-water-adapted littoral chironomid taxa (Cladopelma, Cryptochironomus, Polypedilum) recorded increases. The post-1990 records reflected continued increases in warm-water taxa, changes in the benthic:pelagic trophic structure, and reversal of previous trends in the δ¹³C_org, %Organic Carbon, and δ¹⁵N profiles, suggestive of increased aquatic productivity. The meteorological station at Gillam, Manitoba, also recorded warming (1.5 °C) and a reduction in snowfall during that time period. A reduction in spring recharge may have increased littoral habitat associated with lake-level drawdown. The climate-driven shift observed ~ 1980 is in generally good agreement with other regional analyses, which show regime shifts occurred ~ 1995. The earlier lake response (~ 1980), however, demonstrates the role of increased catchment-mediated influences on northern boreal lake productivity that may only appear in records with sufficiently high resolution and multiple paleolimnological indicators.

古环境方法的应用为加拿大北部水生生态系统对气候变暖的响应幅度和时机提供了见识。我们检查了马尼托巴省北部巴克兰湖沉积岩心中的亚化石生物体（双翅目：Chironomidae）和地球化学指标（有机碳和元素氮以及稳定的同位素组成），以评估近期变暖（1981-2011年）对中亚北极的影响加拿大地区。古湖泊学记录的早期（1830-1980年）的特征是相对较低的手足类生物多样性（N2〜6），主要由深部分类群（Orthocladius consobrinus和Chironomus）组成，沉积物中有机物含量低（<12％），低C：N比（<9），和高的δ ¹⁵N值（> 3‰），表示氮需求低的冷水环境。在1910年至1980年之间，基本分类单元有所减少，而沿海分类单元（例如，克拉多齿tar属cuscus-group）则逐渐增加。1980年后的沉积物核心区间具有明显的地球化学特征，与δ下降¹³ Ç_组织从- 27.5‰几乎- 29‰，与变暖相一致，增加了地面的影响，并增加了降雪和径流。我们发现大量的推断变暖（+1至2°C），与被1980年以前的典型推断相比，几种被尺虫推断的温度高出将近3°C。同时，几种适应温水的滨海日光生物分类群（Cladopelma，Cryptochironomus，Polypedilum）记录的增长。在1990年后记录反映的持续温水类群的增加，改变了海底：远洋营养结构，和以往的趋势逆转的δ ¹³ C ^_组织，％有机碳和δ ¹⁵N个剖面，表明水生生产力提高。曼尼托巴省吉拉姆（Gillam）的气象站也记录了这段时间的变暖（1.5°C）和降雪量的减少。春季补给量的减少可能会增加与湖面水位下降相关的沿海栖息地。大约在1980年之前观测到的气候驱动的变化与其他区域分析基本吻合，这表明在1995年之前发生了政权变化。但是，较早的湖泊响应（〜1980年）表明，汇水作用对北部北方湖泊的影响增加了仅在具有足够高的分辨率和多种古湖泊学指标的记录中才会出现的生产力。