From Sea to Sea: Canada's Three Oceans of Biodiversity

Evaluating and understanding biodiversity in marine ecosystems are both necessary and challenging for conservation. This paper compiles and summarizes current knowledge of the diversity of marine taxa in Canada's three oceans while recognizing that this compilation is incomplete and will change in the future. That Canada has the longest coastline in the world and incorporates distinctly different biogeographic provinces and ecoregions (e.g., temperate through ice-covered areas) constrains this analysis. The taxonomic groups presented here include microbes, phytoplankton, macroalgae, zooplankton, benthic infauna, fishes, and marine mammals. The minimum number of species or taxa compiled here is 15,988 for the three Canadian oceans. However, this number clearly underestimates in several ways the total number of taxa present. First, there are significant gaps in the published literature. Second, the diversity of many habitats has not been compiled for all taxonomic groups (e.g., intertidal rocky shores, deep sea), and data compilations are based on short-term, directed research programs or longer-term monitoring activities with limited spatial resolution. Third, the biodiversity of large organisms is well known, but this is not true of smaller organisms. Finally, the greatest constraint on this summary is the willingness and capacity of those who collected the data to make it available to those interested in biodiversity meta-analyses. Confirmation of identities and intercomparison of studies are also constrained by the disturbing rate of decline in the number of taxonomists and systematists specializing on marine taxa in Canada. This decline is mostly the result of retirements of current specialists and to a lack of training and employment opportunities for new ones. Considering the difficulties encountered in compiling an overview of biogeographic data and the diversity of species or taxa in Canada's three oceans, this synthesis is intended to serve as a biodiversity baseline for a new program on marine biodiversity, the Canadian Healthy Ocean Network. A major effort needs to be undertaken to establish a complete baseline of Canadian marine biodiversity of all taxonomic groups, especially if we are to understand and conserve this part of Canada's natural heritage

Coherence of long-term variations of zooplankton in two sectors of the California Current System

We analyzed long-term (56-year) variations in springtime biomass of the zooplankton of the California Current System from two primary regions sampled by CalCOFI: Southern California (SC) and Central California (CC) waters. All organisms were enumerated from the plankton samples and converted to organic carbon biomass using length-carbon relationships, then aggregated into 19 major taxa. Planktonic copepods dominate the carbon biomass in both SC (59%) and CC (46%), followed by euphausiids (18% and 25% of mean biomass in SC and CC, respectively). Pelagic tunicates, especially salps and doliolids, constituted a higher fraction of the biomass in CC (13%) than in SC (5%). There was no long-term trend detectable in total zooplankton carbon biomass, in marked contrast to a decline in zooplankton displacement volume in both regions. The difference between these biomass metrics is accounted for by a long-term decline in pelagic tunicates (particularly salps), which have a relatively high ratio of biovolume:carbon. The decline in pelagic tunicates was accompanied by a long-term increase in water column density stratification. No other taxa showed a decline over the duration of the study, apart from salps and pyrosomes in SC and doliolids in CC. Some zooplankton taxa showed compensatory increases over the same time period (ostracods, large decapods, and calycophoran siphonophores in both SC and CC; appendicularians and polychaetes in SC). Two tests for ecosystem shifts, a sequential algorithm and the cumulative sum of anomalies (CuSum) approach, failed to detect changes in 1976-1977 in total carbon biomass, displacement volume, or most individual major taxa, suggesting that aggregated biomass is an insensitive indicator of climate forcing. In contrast, both techniques revealed a cluster of step-like changes associated with the La Niña of 1999. The major El Niño's in the past half century have consistently depressed total zooplankton biomass and biomass of many major taxa in both SC and CC, although such effects are transitory. Much, but not all, of the interannual variability in zooplankton is shared between the Southern and Central California sectors of the California Current System. © 2007 Elsevier Ltd. All rights reserved

Comparative zooplankton sampling efficiency of a ring net and bongo net with comments on pooling of subsamples

We analyzed the comparative sampling efficiency of CalCOFI 1 m diameter ring nets and bongo nets in a series of paired comparisons from the California Current. Seventeen major taxa of holozooplankton were enumerated and species-specific analyses were carried out for hyperiid amphipods. The only consistent difference detected between these two nets was a significant increase in abundance of salps in the bongo net. In contrast with comparisons of abundance, the species diversity of hyperiid amphipods was higher when estimated from ring net than from bongo net collections, at higher numbers of individuals enumerated. Analysis of a sample pooling procedure revealed that the average abundance of the more numerous taxa was generally similar, whether determined by enumerating plankton samples individually or from a pooled sample comprising quantitative splits of individual samples. The average abundance of rare taxa was not well represented in the pooled sample. Sample pooling is particularly inappropriate for studies of pelagic species diversity

Long-term changes in pelagic tunicates of the California Current

This study analyzes interannual variability in springtime carbon biomass of pelagic tunicates (salps, doliolids, pyrosomes, and appendicularians) over the period 1951-2002 from CalCOFI zooplankton samples taken in the southern sector of the California Current System. The results provide evidence for ecosystem changes between 1976 and 1977 and perhaps between 1998 and 1999. A cool-phase group of salps (Salpa maxima, Pegea socia, Cyclosalpa bakeri, and Cyclosalpa affinis) that was present between 1951 and 1976 was nearly undetectable in Southern California waters during the warm phase of the California Current (1977-98). C. bakeri and C. affinis then re-appeared in 2001. A persistent group of salps (Salpa aspera, Salpa fusiformis, Thalia democratica, Ritteriella picteti, Iasis zonaria) was observed throughout the study period. The cool-phase species tend to be distributed in mid-latitudes, while the distributions of the persistent species extend to equatorial waters. The cool-phase species have been reported to show little evidence of diel vertical migration, while most of the persistent species are reported to be diel migrants. No distinct multi-decadal patterns were observed in the dominant doliolid Dolioletta gegenbauri, but the rarer subtropical doliolid Doliolum denticulatum was present predominantly during the warm phase of the California Current. The recurrence patterns and biogeographic distributions of both salps and doliolids suggest that the warm phase of the California Current was accompanied by at least some intervals of anomalous transport "seeding" organisms from the south. Variations in total pyrosome and total appendicularian carbon biomass are not clearly related to long-term trends in the water column, although the highest pyrosome biomass occurred in earlier decades and appendicularian biomass has increased since 1999. Long-term changes in the biomass of pelagic tunicates appear to be chiefly responsible for the previously documented long-term decline in California Current total zooplankton biomass. The pattern of decline appeared to reverse in 1999, with a shift to cooler temperatures, somewhat reduced thermal stratification, and an increase in biomass of total zooplankton and of pelagic tunicates. © 2003 Elsevier Ltd. All rights reserved

Long-term changes in pelagic tunicates of the California Current

This study analyzes interannual variability in springtime carbon biomass of pelagic tunicates (salps, doliolids, pyrosomes, and appendicularians) over the period 1951-2002 from CalCOFI zooplankton samples taken in the southern sector of the California Current System. The results provide evidence for ecosystem changes between 1976 and 1977 and perhaps between 1998 and 1999. A cool-phase group of salps (Salpa maxima, Pegea socia, Cyclosalpa bakeri, and Cyclosalpa affinis) that was present between 1951 and 1976 was nearly undetectable in Southern California waters during the warm phase of the California Current (1977-98). C. bakeri and C. affinis then re-appeared in 2001. A persistent group of salps (Salpa aspera, Salpa fusiformis, Thalia democratica, Ritteriella picteti, Iasis zonaria) was observed throughout the study period. The cool-phase species tend to be distributed in mid-latitudes, while the distributions of the persistent species extend to equatorial waters. The cool-phase species have been reported to show little evidence of diel vertical migration, while most of the persistent species are reported to be diel migrants. No distinct multi-decadal patterns were observed in the dominant doliolid Dolioletta gegenbauri, but the rarer subtropical doliolid Doliolum denticulatum was present predominantly during the warm phase of the California Current. The recurrence patterns and biogeographic distributions of both salps and doliolids suggest that the warm phase of the California Current was accompanied by at least some intervals of anomalous transport "seeding" organisms from the south. Variations in total pyrosome and total appendicularian carbon biomass are not clearly related to long-term trends in the water column, although the highest pyrosome biomass occurred in earlier decades and appendicularian biomass has increased since 1999. Long-term changes in the biomass of pelagic tunicates appear to be chiefly responsible for the previously documented long-term decline in California Current total zooplankton biomass. The pattern of decline appeared to reverse in 1999, with a shift to cooler temperatures, somewhat reduced thermal stratification, and an increase in biomass of total zooplankton and of pelagic tunicates. © 2003 Elsevier Ltd. All rights reserved

Hyperiid amphipods as indicators of climate change in the California Current

We investigated long-term changes in the abundance and species composition of hyperiid amphipods in the Southern California Bight and nearby waters from twelve springime CalCOFI cruises spanning the period 1951-1997. Sixty-two hyperiid species were detected in the study region. We found dimunition in species diversity and in total hyperiid abundance during the studied period. Despite high interannual variability, there was higher species richness, evenness of species numbers, and abundances of hyperiids in an earlier time period (1951 to 1972) and generally lower species richness, evenness, and abundances in a more recent time period (1979 to 1997). Variations in abundance of total hyperiids were significantly correlated with variations in abundance of presumed gelatinous zooplankton hosts, especially salps, physonect siphonophores, and pyrosomes. Species-specific correlations showed significant associations between ten species of hyperiids and different species of salps, siphonphores, and medusae. Some amphipods were correlated with more than one host. Hyperiid amphipod assemblages appear to be sensitive to large-scale climate changes in the NE Pacific, through either direct responses or indirectly through their association as parasitoids on gelatinous hosts

Coherence of long-term variations of zooplankton in two sectors of the California Current System

We analyzed long-term (56-year) variations in springtime biomass of the zooplankton of the California Current System from two primary regions sampled by CalCOFI: Southern California (SC) and Central California (CC) waters. All organisms were enumerated from the plankton samples and converted to organic carbon biomass using length-carbon relationships, then aggregated into 19 major taxa. Planktonic copepods dominate the carbon biomass in both SC (59%) and CC (46%), followed by euphausiids (18% and 25% of mean biomass in SC and CC, respectively). Pelagic tunicates, especially salps and doliolids, constituted a higher fraction of the biomass in CC (13%) than in SC (5%). There was no long-term trend detectable in total zooplankton carbon biomass, in marked contrast to a decline in zooplankton displacement volume in both regions. The difference between these biomass metrics is accounted for by a long-term decline in pelagic tunicates (particularly salps), which have a relatively high ratio of biovolume:carbon. The decline in pelagic tunicates was accompanied by a long-term increase in water column density stratification. No other taxa showed a decline over the duration of the study, apart from salps and pyrosomes in SC and doliolids in CC. Some zooplankton taxa showed compensatory increases over the same time period (ostracods, large decapods, and calycophoran siphonophores in both SC and CC; appendicularians and polychaetes in SC). Two tests for ecosystem shifts, a sequential algorithm and the cumulative sum of anomalies (CuSum) approach, failed to detect changes in 1976-1977 in total carbon biomass, displacement volume, or most individual major taxa, suggesting that aggregated biomass is an insensitive indicator of climate forcing. In contrast, both techniques revealed a cluster of step-like changes associated with the La Niña of 1999. The major El Niño's in the past half century have consistently depressed total zooplankton biomass and biomass of many major taxa in both SC and CC, although such effects are transitory. Much, but not all, of the interannual variability in zooplankton is shared between the Southern and Central California sectors of the California Current System. © 2007 Elsevier Ltd. All rights reserved

Changes in the copepod community during the 1992–93 Enso at San Lorenzo channel, Gulf of California

The structure of the copepod community from the San Lorenzo Channel, Gulf of California, is described for 1990 and the 1992–93 ENSO. The main difference between sampling periods was the decrease of the calanoid Nannocalanus minor. This oceanic species, distributed mainly in the equatorial zone, was one of the dominant in the plankton of the channel from February to August 1990. During the 1992–93 ENSO it appeared to be partially displaced by another equatorial but smaller species, Clausocalanus arcuicornis, and the tropical coastal species, Undinula vulgaris. Among the carnivores, Euchaeta marina decreased during ENSO, while the incidence of Candacia truncata and Candacia catula was observed. The mesh size of the net used noticeably affected the community structure observed, due to the escape of organisms through the net. With the net of 300 µm mesh size, 30% more species were collected than with the net of 500 µm, and the abundances of the smaller species presented high escape percentages with the latter

Multi-decadal variations in calcareous holozooplankton in the California Current System: thecosome pteropods, heteropods, and foraminifera

We examine long-term (1951-2008) variability of three major taxa of calcareous holozooplankton (aragonitesecreting thecosome pteropods and heteropods, and calcitesecreting large planktonic foraminifera) in light of recent interest in the impingement of waters undersarurated with respect to aragonite onto continental shelf depths in the California Current System. We assess interannual variability in springtime abundances of zooplankton sampled in the epipelagic layer, using CalCOFI (California Cooperative Oceanic Fisheries Investigations) zooplankton samples from two regions: Southern California (SC) and Central California (CC). Thecosome pteropods show no evidence of recent declines in abundance in SC or CC waters. In SC, sampling was sufficient to conclude that heteropods and large foraminifera also show no evidence of declines in abundance in recent years. These results do not preclude asyet undetected changes in vertical distributions or shell morphology, and underscore the importance of sustained in situ measurement programs in order to detect and understand changes to pelagic ecosystems. Copyright 2009 by the American Geophysical Union