Climate change is leading to phenological shifts across a wide range of species globally. Polar oceans are hotspots of rapid climate change where sea ice dynamics structure ecosystems and organismal life cycles are attuned to ice seasonality. To anticipate climate change impacts on populations and ecosystem services, it is critical to understand ecosystem phenology to determine species activity patterns, optimal environmental windows for processes like reproduction, and the ramifications of ecological mismatches. Since 1991, the Palmer Antarctica Long‐Term Ecological Research (LTER) program has monitored seasonal dynamics near Palmer Station. Here, we review the species that occupy this region as year‐round residents, seasonal breeders, or periodic visitors. We show that sea ice retreat and increasing photoperiod in the spring trigger a sequence of events from mid‐November to mid‐February, including Adélie penguin clutch initiation, snow melt, calm conditions (low winds and warm air/sea temperature), phytoplankton blooms, shallow mixed layer depths, particulate organic carbon flux, peak humpback whale abundances, nutrient drawdown, and bacterial accumulation. Subsequently, from May to June, snow accumulates, zooplankton indicator species appear, and sea ice advances. The standard deviation in the timing of most events ranged from ~20 to 45 days, which was striking compared with Adélie penguin clutch initiation that varied <1 week. In general, during late sea ice retreat years, events happened later (~5 to >30 days) than mean dates and the variability in timing was low (<20%) compared with early ice retreat years. Statistical models showed the timing of some events were informative predictors (but not sole drivers) of other events. From an Adélie penguin perspective, earlier sea ice retreat and shifts in the timing of suitable conditions or prey characteristics could lead to mismatches, or asynchronies, that ultimately influence chick survival via their mass at fledging. However, more work is needed to understand how phenological shifts affect chick thermoregulatory costs and the abundance, availability, and energy content of key prey species, which support chick growth and survival. While we did not detect many long‐term phenological trends, we expect that when sea ice trends become significant within our LTER time series, phenological trends and negative effects from ecological mismatches will follow.
The timing of biological events in plants and animals, such as migration and reproduction, is shifting due to climate change. Anadromous fishes are particularly susceptible to these shifts as they are subject to strong seasonal cycles when transitioning between marine and freshwater habitats to spawn. We used linear models to determine the extent of phenological shifts in adult Alewife
- NSF-PAR ID:
- 10366541
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Marine and Coastal Fisheries
- Volume:
- 14
- Issue:
- 2
- ISSN:
- 1942-5120
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
more » « less
Abstract The common carp,
Cyprinus carpio , is a large, long‐lived, fecund and mobile cyprinid, which evolved in complex inter‐braided Ponto‐Caspian rivers that experience both springtime flooding and freezing winters. Studies suggest adults often move to productive, shallow lakes and floodplains to spawn because they often lack egg predators and then return to deeper normoxic waters to overwinter. Whether these movements involve individuals consistently selecting, or homing to, the same spawning and refuge lakes as part of a strategy benefiting their reproductive success is unknown. To address this question, we examined the movements of 67 radio‐tagged adult carp for 3 years in a watershed with 11 interconnected lakes. Carp were tagged and released into a centrally located, normoxic deep lake in spring and fall. Each spring over 95% of its adults left via a single stream and swam into one of 5 shallow lakes, with most individuals (84%) selecting the same lake(s) in which to spawn each year (median Bhattacharyya affinity coefficient of similarity of 0.82). Young were later found in those lakes without egg predators, which cannot survive winter anoxia. After spawning, carp spent summers moving between productive lakes in an individualistic fashion, presumably foraging, with most (89%) eventually returning to the same deep lake to overwinter (median Bhattacharyya affinity of 1.0). These movements appear to reveal a life‐history tactic involving seasonal homing migration, first to a spawning location and later to winter refuges, that is well adapted to productive but highly heterogeneous and interconnected freshwater environments. -
more » « less
Abstract The timing of avian migration has evolved to exploit critical seasonal resources, yet plasticity within phenological responses may allow adjustments to interannual resource phenology. The diversity of migratory species and changes in underlying resources in response to climate change make it challenging to generalize these relationships.
We use bird banding records during spring and fall migration from across North America to examine macroscale phenological responses to interannual fluctuations in temperature and long‐term annual trends in phenology.
In total, we examine 19 species of North American wood warblers (family Parulidae), summarizing migration timing from 2,826,588 banded birds from 1961 to 2018 across 46 sites during spring and 124 sites during fall.
During spring, warmer spring temperatures at banding locations translated to earlier median passage dates for 16 of 19 species, with an average 0.65‐day advancement in median passage for every 1°C increase in temperature, ranging from 0.25 to 1.26 days °C−1. During the fall, relationships were considerably weaker, with only 3 of 19 species showing a relationship with temperature. In those three cases, later departure dates were associated with warmer fall periods. Projecting these trends forward under climate scenarios of temperature change, we forecast continued spring advancements under shared socioeconomic pathways from 2041 to 2060 and 2081 to 2100 and more muted and variable shifts for fall.
These results demonstrate the capacity of long‐distance migrants to respond to interannual fluctuations in temperatures, at least during the spring, and showcase the potential of North American bird banding data understanding phenological trends across a wide diversity of avian species.
-
more » « less
Abstract Seasonal sea ice retreat is known to stimulate Southern Ocean phytoplankton blooms, but depth‐resolved observations of their evolution are scarce. Autonomous float measurements collected from 2015–2019 in the eastern Weddell Sea show that spring bloom initiation is closely linked to sea ice retreat timing. The appearance and persistence of a rare open‐ocean polynya over the Maud Rise seamount in 2017 led to an early bloom and high annual net community production. Widespread early ice retreat north of Maud Rise in 2017, however, had a similar effect, suggesting that the polynya most impacted the timing of bloom initiation. Still, higher productivity rates at Maud Rise relative to the surrounding region are observed in all years, likely supported by flow‐topography interactions. The longer growing season in 2017–2018 also allowed for separation of distinct spring and fall bloom signals, the latter of which was primarily subsurface and associated with mixed‐layer deepening.
-
more » « less
Abstract The timing of life history events in many plants and animals depends on the seasonal fluctuations of specific environmental conditions. Climate change is altering environmental regimes and disrupting natural cycles and patterns across communities. Anadromous fishes that migrate between marine and freshwater habitats to spawn are particularly sensitive to shifting environmental conditions and thus are vulnerable to the effects of climate change. However, for many anadromous fish species the specific environmental mechanisms driving migration and spawning patterns are not well understood. In this study, we investigated the upstream spawning migrations of river herring
Alosa spp. in 12 coastal Massachusetts streams. By analyzing long‐term data sets (8–28 years) of daily fish counts, we determined the local influence of environmental factors on daily migration patterns and compared seasonal run dynamics and environmental regimes among streams. Our results suggest that water temperature was the most consistent predictor of both daily river herring presence–absence and abundance during migration. We found inconsistent effects of streamflow and lunar phase, likely due to the anthropogenic manipulation of flow and connectivity in different systems. Geographic patterns in run dynamics and thermal regimes suggest that the more northerly runs in this region are relatively vulnerable to climate change due to migration occurring later in the spring season, at warmer water temperatures that approach thermal maxima, and during a narrower temporal window compared to southern runs. The phenology of river herring and their reliance on seasonal temperature patterns indicate that populations of these species may benefit from management practices that reduce within‐stream anthropogenic water temperature manipulations and maintain coolwater thermal refugia.
