| Habitat Usage of Georges
Bank by the Cryptic Copepods Pseudocalanus moultoni and P. newmani during January to June 1999 |
| Ann Bucklin1, Peter H. Wiebe2, Dennis J. McGillicuddy2, | |
| Christopher Manning3, Kaitlyn G. Bonner3*, and Meredith A. Bailey3* | |
| 1University of Connecticut, Avery Point CT | |
| 2Woods Hole Oceanographic Institution, Woods Hole MA | |
| 3University of New Hampshire, Durham NH |
| "Primary field investigations 1997 and..." |
| Primary field investigations 1997 and 1999 | |
| For 1997, Mapping spring evolution of vertically-integrated distribution and abundance of Pseudocalanus moultoni and P. newmani on Georges Bank during January to June | |
| For 1997, 2-D adjoint modeling of biological-physical processes controlling spring evolution, including biological sources and sinks and current flow | |
| For 1999, analysis of vertically-stratified regional abundance patterns mapped to a standard grid with 5 bathymetric and circulation zones | |
| Possible 3-D adjoint modeling of 1999 data | |
| Ms in prep describing vertical distribution and abundance of the two species with implications for transport and retention on Georges Bank. |
| "Pseudocalanus moultoni and P." |
| Pseudocalanus moultoni and P. newmani likely have distinct patterns of transport, retention, and maintenance on Georges Bank. | |
| There were distinct source regions for the two species in both 1997 and 1999. By June, the speciesŐ distributions were overlapping on the crest of the Bank. | |
| Based on total Bank-wide abundance, the spring evolution of abundance of the two species was similar, with earlier build-up for P. newmani. | |
| The spring evolution of abundance of the two species differed among five regions of Georges Bank, with the exception of the Northeast peak. | |
| Vertical distributions of the two species differed both Bank-wide and within each region, with P. moultoni generally less abundant in the top 15 m. |
| "Pseudocalanus moultoni and P." |
| Pseudocalanus moultoni and P. newmani are morphologically cryptic but genetically distinct, differing by 18% in mtCOI sequence. | |
| Multiplexed, species-specific PCR (SS-PCR) was used to identify individual copepods. Reactions were done in 96-well plates, with controls. | |
| For the U.S. GLOBEC samples, only adult females were identified. |
| 1997 Broad-scale Mapping for Pseudocalanus spp. |
| Vertically-integrated (0 – 40 m) objectively-analyzed monthly distributions of P. moultoni and P. newmani females for February to June 1997, based on U.S. GLOBEC Georges Bank Study Broad-scale surveys. |
| 1997 Adjoint Numerical Modeling |
| 1997 species abundances were assimilated into a coupled physical-biological model. | |
| The forward problem was posed as an advection - diffusion - reaction equation for the copepod concentration. | |
| The adjoint method of data assimilation was used to invert for the biological sources and sinks implied by the observed changes in abundance between surveys and the flow during the intervening period. |
| Slide 7 |
| 1999 Broad-scale Mapping for Pseudocalanus spp. |
| Objectively-analyzed maps for vertically-integrated (top-to-bottom) 1999 distributions showed parallels with the 1997 maps, models, and cartoons. | |
| Early Spring distributions (source regions) were apparently distinct; Summer distributions (destinations) were overlapping on top of Georges Bank. |
| Why Does Vertical Distribution Matter? |
| Vertical distribution determines transport trajectories on the Bank: copepods in the surface waters (0- 15 m) are advected by Eckman transport. | |
| Copepods below the Eckman layer are less subject to transport. The tidal mixing front may help retain deeper-dwelling copepods on the Bank. | |
| Remaining deeper in the water column may represent a strategy to aid retention and avoid loss from Georges Bank for small copepods like Pseudocalanus spp. |
| 1999 Vertical Distributions of Pseudocalanus spp. |
| Regional Analysis using a Standard Grid |
| 1999 Regional Abundances of Pseudocalanus spp. |
| Total monthly abundances for each species for each region showed differences in month-to-month patterns of abundance for all regions except the Northeast Peak. |
| Pseudocalanus spp. in the Western Gulf of Maine |
| In MARMAP surveys 1977 – 1987, Pseudocalanus spp. shows a seasonal cycle of abundance, with two population centers: | |
| Western Gulf of Maine | |
| Georges Bank | |
| Davis (1984) hypothesized the Western Gulf of Maine is a source region for the Georges Bank population | |
| McGillicuddy et al. (1998) concluded that the populations are functionally distinct, with geographically-specific regions of growth and mortality |
| Pseudocalanus spp. in the Western Gulf of Maine |
| COOA/REACH samples were analyzed for seasonal cycles of all copepod species occurring in the samples (Manning & Bucklin, 2004). |
| Pseudocalanus spp. in the Western Gulf of Maine |
| Slide 16 |
| Slide 17 |
| Slide 18 |
| "The two Pseudocalanus spp." |
| The two Pseudocalanus spp. likely have distinct patterns of transport, retention, and maintenance on Georges Bank. | |
| There were distinct source regions for the two species in both 1997 and 1999. By June, the speciesŐ distributions were overlapping on the crest of the Bank. | |
| Based on total Bank-wide abundance, the spring evolution of abundance of the two species was similar, with earlier build-up for P. newmani. | |
| The spring evolution of abundance of the two species differed among five regions of Georges Bank, with the exception of the Northeast peak. | |
| Vertical distributions of the two species differed both Bank-wide and within each region, with P. moultoni generally less abundant in the top 15 m. |
| Acknowledgments |