The Takeaway:
Differential phenological responses within and across trophic community levels and periods of the annual cycle in coastal and pelagic ecosystems is resulting in mismatch with prey (Edwards and Richardson 2004). Ocean circulation and upwelling at both inter-decadal and multi-decadal time scales (Chavez et al. 2003) are also critical to larval transport (distributional timing) and thus community wide phenology. In addition to increasing temperature, changing ocean chemistry (e.g acidity) is extremely important to species phenology, performance, and survival (Harley et al. 2006, Poloczanska et al. 2013). All of these factors are interacting with harvesting practices and over-fishing to impacts survival, recruitment, and abundance of fish populations including many commercially important species.
Differential phenological responses within and across trophic community levels and periods of the annual cycle in coastal and pelagic ecosystems is resulting in mismatch with prey (Edwards and Richardson 2004). Ocean circulation and upwelling at both inter-decadal and multi-decadal time scales (Chavez et al. 2003) are also critical to larval transport (distributional timing) and thus community wide phenology. In addition to increasing temperature, changing ocean chemistry (e.g acidity) is extremely important to species phenology, performance, and survival (Harley et al. 2006, Poloczanska et al. 2013). All of these factors are interacting with harvesting practices and over-fishing to impacts survival, recruitment, and abundance of fish populations including many commercially important species.
Pacific Ocean & Remote sensing
Remotely sensed data, especially ocean-color and Sea Surface Temperature (SST) are available continuously since 1997 at high spatial (1 km) and temporal (daily) resolution, allowing close monitoring of the phenology of phytoplankton biomass (estimated in chlorophyll units), their association with temperature change, and ultimately the analysis of large-scale, interannual and decadal variability in phytoplankton phenology (Racault et al. 2012).
Remotely sensed data, especially ocean-color and Sea Surface Temperature (SST) are available continuously since 1997 at high spatial (1 km) and temporal (daily) resolution, allowing close monitoring of the phenology of phytoplankton biomass (estimated in chlorophyll units), their association with temperature change, and ultimately the analysis of large-scale, interannual and decadal variability in phytoplankton phenology (Racault et al. 2012).
Figure 16. Monthly sea surface chlorophyll a in the Pacific Ocean as observed during El Niño, neutral, and La Niña conditions. Chlorophyll a is a proxy for phytoplankton abundance. The El Niño and neutral images are derived using data acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite, while the La Niña image is derived from data acquired by the Sea-Viewing Wide Field-of View Sensor (SeaWiFS) Image credits: www.oceancolor.gsfc.nasa.gov ; www.ncdc.gov.
Plankton
At the base of the marine food web are zooplankton which show large (1-3 months) interannual variability in timing, most strongly correlated with water temperature during and before the growing season acting as a timing cue (Mackas et al. 2012). Recent warming trends and phenological responses of zooplankton may be moving species outside their local seasonal optima, impacting community composition and trophic interactions (Mackas et al. 2012), such as predator-prey dynamics (Costello et al. 2006). The role of phenology in changing community interactions in marine systems may often be part of much more complicated interactions of climate-induced changes such as water water temperatures with other anthropogenic disturbances including fishery harvests and eutrophication (Oguz et al. 2008).
At the base of the marine food web are zooplankton which show large (1-3 months) interannual variability in timing, most strongly correlated with water temperature during and before the growing season acting as a timing cue (Mackas et al. 2012). Recent warming trends and phenological responses of zooplankton may be moving species outside their local seasonal optima, impacting community composition and trophic interactions (Mackas et al. 2012), such as predator-prey dynamics (Costello et al. 2006). The role of phenology in changing community interactions in marine systems may often be part of much more complicated interactions of climate-induced changes such as water water temperatures with other anthropogenic disturbances including fishery harvests and eutrophication (Oguz et al. 2008).
At the base of the oceanic food web, variability in zooplankton phenology is commonly correlated with water temperature anomalies during and before the growing season driving earlier phenology; however, species with seasonal maxima in late summer or autumn have a delayed response (Mackas et al. 2012). Globally, from 1995-2015, phytoplankton phenologies have varied strongly by latitude and productivity regime such that those in high-production regimes are governed by insolation, while those in low-production regimes are constrained by vertical mixing (Boyce et al. 2017).
Interestingly, the concept of phenological mismatch was first developed to explain annual variation in recruitment of North Atlantic fish populations (Cushing 1990). Cushing (1990) proposed that there was a critical developmental period of food-mediated mortality driven by the overlap in time and space of larval fish abundance with the abundance of their zooplankton prey. This hypothesis has since been explicitly examined and supported in aquatic (and terrestrial) ecosystems over the past three decades, highlighting the critical importance of community-wide phenological responses to climate change, particularly between plankton and upper levels of food webs (Edwards and Richardson 2004, Mackas et al. 2012, Poloczanska et al. 2013).
In the Eastern Boundary Current upwelling off the coast of central California, 39% of phenological events of 43 species monitored over 58 years occurred earlier in recent decades and zooplankton did not shift synchronously with most fish, so that even many fish that did not shift their phenology were still experiencing mismatch with their prey with potential impacts on recruitment (Asch 2015).
In 2005, there were anomalous upwelling patterns in the northern California Current Ecosystem when spring transition was delayed more than a month, substantial upwelling initiation was delayed by about two months (Kosro et al. 2006, Barth et al. 2007). A concurrent 2° C positive temperature anomaly in nearshore waters off central Oregon, a 50% decrease in surf-zone chlorophyll, and a 30% reduction in spring nitrate also occurred at this time (Barth et al. 2007), 2007) along with a northward jet stream shift which increased and advanced along the Northwest coast from northern California to British Columbia. Species with a more northern distributions were reduced in abundance, many southern species shifted their distribution north such as larvae of Pacific hake and jack mackerel which were found off Oregon and British Columbia, a ~1,000-km shift in distribution (Brodeur et al. 2006), sardine and anchovy in Southeast Alaska, and many species shifted their life cycle phenology earlier (Mackas et al. 2006), while offshore species including ocean sunfish, Pacific pomfret, opah, and yellowtail increased in abundance (Brodeur et al. 2006). Impacts on other marine taxa included in 2005 included altered timing of reproduction and recruitment of mussels and barnacles (Barth et al. 2007) and reduced breeding success of Cassin’s auklet due to reduced krill abundance resulting from delayed upwelling (Sydeman et al. 2006). This example highlights the complex interactions between climate, other physical earth processes such as ocean dynamics, and species phenology and the cascading impacts throughout populations, communities and ecosystems.
Interestingly, the concept of phenological mismatch was first developed to explain annual variation in recruitment of North Atlantic fish populations (Cushing 1990). Cushing (1990) proposed that there was a critical developmental period of food-mediated mortality driven by the overlap in time and space of larval fish abundance with the abundance of their zooplankton prey. This hypothesis has since been explicitly examined and supported in aquatic (and terrestrial) ecosystems over the past three decades, highlighting the critical importance of community-wide phenological responses to climate change, particularly between plankton and upper levels of food webs (Edwards and Richardson 2004, Mackas et al. 2012, Poloczanska et al. 2013).
In the Eastern Boundary Current upwelling off the coast of central California, 39% of phenological events of 43 species monitored over 58 years occurred earlier in recent decades and zooplankton did not shift synchronously with most fish, so that even many fish that did not shift their phenology were still experiencing mismatch with their prey with potential impacts on recruitment (Asch 2015).
In 2005, there were anomalous upwelling patterns in the northern California Current Ecosystem when spring transition was delayed more than a month, substantial upwelling initiation was delayed by about two months (Kosro et al. 2006, Barth et al. 2007). A concurrent 2° C positive temperature anomaly in nearshore waters off central Oregon, a 50% decrease in surf-zone chlorophyll, and a 30% reduction in spring nitrate also occurred at this time (Barth et al. 2007), 2007) along with a northward jet stream shift which increased and advanced along the Northwest coast from northern California to British Columbia. Species with a more northern distributions were reduced in abundance, many southern species shifted their distribution north such as larvae of Pacific hake and jack mackerel which were found off Oregon and British Columbia, a ~1,000-km shift in distribution (Brodeur et al. 2006), sardine and anchovy in Southeast Alaska, and many species shifted their life cycle phenology earlier (Mackas et al. 2006), while offshore species including ocean sunfish, Pacific pomfret, opah, and yellowtail increased in abundance (Brodeur et al. 2006). Impacts on other marine taxa included in 2005 included altered timing of reproduction and recruitment of mussels and barnacles (Barth et al. 2007) and reduced breeding success of Cassin’s auklet due to reduced krill abundance resulting from delayed upwelling (Sydeman et al. 2006). This example highlights the complex interactions between climate, other physical earth processes such as ocean dynamics, and species phenology and the cascading impacts throughout populations, communities and ecosystems.
RESOURCES
Ocean Color: NASA's OceanColor Web is supported by the Ocean Biology Processing Group (OBPG) at NASA's Goddard Space Flight Center. Our responsibilities include the collection, processing, calibration, validation, archive and distribution of ocean-related products from a large number of operational, satellite-based remote-sensing missions providing ocean color, sea surface temperature and sea surface salinity data to the international research community since 1996. https://oceancolor.gsfc.nasa.gov/
Sea-viewing Wide Field-of-view Sensor (SeaWiFS): The purpose of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) mission was to provide quantitative data on global ocean bio-optical properties to the Earth science community. The purpose of SeaWiFS data is to examine oceanic factors that affect global change and to assess the oceans’ role in the global carbon cycle, as well as other biogeochemical cycles. The SeaWiFS project aims to obtain accurate ocean color data from the world’s oceans, to process these data in conjunction with ancillary data into meaningful biological parameters, such as photosynthesis rates, and to make these data readily available to researchers. https://eospso.nasa.gov/missions/sea-viewing-wide-field-view-senso
Ocean Color: NASA's OceanColor Web is supported by the Ocean Biology Processing Group (OBPG) at NASA's Goddard Space Flight Center. Our responsibilities include the collection, processing, calibration, validation, archive and distribution of ocean-related products from a large number of operational, satellite-based remote-sensing missions providing ocean color, sea surface temperature and sea surface salinity data to the international research community since 1996. https://oceancolor.gsfc.nasa.gov/
Sea-viewing Wide Field-of-view Sensor (SeaWiFS): The purpose of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) mission was to provide quantitative data on global ocean bio-optical properties to the Earth science community. The purpose of SeaWiFS data is to examine oceanic factors that affect global change and to assess the oceans’ role in the global carbon cycle, as well as other biogeochemical cycles. The SeaWiFS project aims to obtain accurate ocean color data from the world’s oceans, to process these data in conjunction with ancillary data into meaningful biological parameters, such as photosynthesis rates, and to make these data readily available to researchers. https://eospso.nasa.gov/missions/sea-viewing-wide-field-view-senso