Southern California Bight 2003 Regional Monitoring Program: IV. Demersal Fishes and Megabenthic Invertebrates
Combined Fish and Invertebrate Site and Species Clusters
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- Figure VI-13. Bathymetric distribution of demersal fish and megabenthic invertebrate site clusters on the southern California shelf at depths of 2-476 m, July-October 2003.
Combined Fish and Invertebrate Site and Species ClustersSelection of Species. The trawl survey sampled 210 stations and collected 61,687 fish and 157,326 invertebrates, or 219,013 fish and invertebrates combined. These represented 142 species of fish and 308 species of invertebrates, or 450 fish and invertebrate species combined. Based upon the screening criteria, all 210 stations representing 212,628 individuals and 167 species were included in the cluster analysis. The cluster analysis delineated nine major site clusters (station clusters), denoting habitats, and seven major species clusters, denoting species assemblages or communities (Figure VI-12; Appendix D-D8 through D-D10). Each site and species cluster was unique, based on the relative proportion of different species clusters within a site cluster and the relative proportion of each species cluster in different site clusters (Figure VI-12). Site Clusters. The site clusters varied by region, depth, and subpopulation (Table VI-8; Figures VI-12 through VI-14). Each site cluster consisted of 1-2 dominant species clusters (Figure VI-12, top). Viewed from the perspective of what species clusters were most important in a site cluster, four species groups were primarily dominant in a single site cluster, but Species Cluster A was dominant in five site clusters (5, 6, 7, 8, 9). The dominant species cluster in Site Cluster 1 was Species Cluster E; in Site Cluster 2, Species Cluster B; in Site Cluster 3, Species Cluster C; and in Site Cluster 4, Species Cluster F (Figure VI-12, top). Site Cluster 2 (Upper Slope) included 18 stations at depths of 225-476 m (Table VI-8; Figures VI-12 through VI-14). This site group is characterized by 18 mainland upper slope sites (Table VI-8, Figure VI-14). Fourteen species occurred in more than 50% of the stations in Site Cluster 2, including 9 species of Species Cluster B, 4 species of Species Cluster E, and 1 species of Species Cluster A (Table VI-9, Appendix D-D10). The most frequently occurring species were Dover sole (94%), northern heart urchin (78%), and bigfin eelpout and offshore blade shrimp (72%; Table VI-9). The most abundant species were northern urchin (28, 938), sea star Myxoderma platyacanthum (9,460), and brittlestar Asteronyx longifissus (4,038; Appendix D-D11). Site Cluster 1 (Upper Slope/Outer Shelf) included 25 stations at depths of 132-322 m (Table VI-8; Figures VI-12 through VI-14). This site group contained 23 mainland upper slope sites and 2 island sites (Table VI-8; Figure VI-14). Nineteen species occurred in more than 50% of the stations in Site Cluster 2 (Table VI-9; Appendix D-D10). All 11 species of Species Cluster E, 4 species of Species Cluster A, 2 species of Species Cluster B, and 1 species of Species Cluster D occurred in more than 50% of the stations within Site Cluster 2 (Table VI-9). The most frequently occurring species were slender sole (100%), Dover sole (96%), and fragile sea urchin (92%; Table VI-9). The most abundant species were fragile sea urchin (15,897), northern heart urchin (7,132), and slender sole (4,038; Appendix D-D11). Site Cluster 7 (Outer Shelf) included 16 stations at depths of 80-192 m (Table VI-8; Figures VI-12 through VI-14). This site group consisted of 10 mainland and 6 island sites (Table VI-8; Figure VI-14). Thirteen species occurred in more than 50% of the stations in Site Cluster 7, including 6 species of Species Cluster A, 3 species of Species Cluster D, and 2 species each of Species Clusters B and E (Table VI-9; Appendix D-D10). The most frequently occurring species were Pacific sanddab (94%), Dover sole (88%), and shortspine combfish (81%; Table VI-9). The most abundant species were white sea urchin (5,132), Pacific sanddab (3,204), and fragile sea urchin (897; Appendix D-D11). Site Cluster 6 (Channel Islands Middle Shelf) included 21 stations at depths of 45-130 m (Table VI-8; Figures VI-12 through VI-14). This site group contained 20 island sites and 1 mainland site (Table VI-8; Figure VI-14). Twenty-one species occurred in more than 50% of the stations in Site Cluster 7, including 18 species of Species Cluster A, 3 species of Species Cluster D, and 1 species of Species Cluster G (Table VI-9; Appendix D-D10). The most frequently occurring species were Pacific sanddab (100%), and red sea star and red octopus (90%; Table VI-9; Appendix D-D10). The most abundant species were white sea urchin (17,465), Pacific sanddab (4,375), and halfbanded rockfish (1,536; Appendix D-D11). Site Cluster 8 (Mainland Middle Shelf) included 16 stations at depths of 57-101 m (Table VI-8; Figures VI-12 through VI-14). This site group formed by 16 mainland middle shelf sites (Table VI-8; Figure VI-14). Twenty-four species occurred in more than 50% of the stations in Site Cluster 8, including 20 species of Species Cluster A, and 2 species each of Species Clusters E and G (Table VI-9; Appendix D-D10). Three species (Pacific sanddab, Dover sole, and longspine combfish) occurred at 100% of the sites (Table VI-9; Appendix D-D10). The most abundant species were white sea urchin (4,710), Pacific sanddab (2,961), and yellowchin sculpin (873; Appendix D-D11). Site Cluster 9 (Middle Shelf/Inner Shelf) included 48 stations at depths of 15-86 m (Table VI-8; Figures VI-12 through VI-14). This site group contains 47 mainland sites and 1 island site (Table VI-8; Figure VI-14). Eighteen species occurred in more than 50% of the stations in Site Cluster 8, including 17 species of Species Cluster A, and 1 species of Species Cluster F (Table VI-9; Appendix D-D10). The most frequently occurring species were Pacific sanddab D10). The most abundant species were white sea urchin (5,617), Pacific sanddab (5,012), and speckled sanddab (2,927; Appendix D-D11). Site Cluster 4 (Inner Shelf/Bays/Harbors) included 20 stations at depths of 4-71 m (Table VI-8; Figures VI-12 through VI-14). This site group consisted of 20 mainland sites with 8 in bays and harbors, 9 on the inner shelf, and 3 on the middle shelf (Table VI-8; Figure VI-14). Six species occurred in more than 50% of the stations in Site Cluster 4, including 4 species of Species Cluster F, and 2 species of Species Cluster A (Table VI-9; Appendix D-D10). The most frequently occurring species were white croaker and hornyhead turbot (70% each) and queenfish (65%) (Table VI-9; Appendix D-D10). The most abundant species were blackspotted bay shrimp (1,701), white croaker (839), and pink seaperch (500; Appendix D-D11). Site Cluster 5 (Inner Shelf) included 30 stations at depths of 7-34 m (Table VI-8; Figures VI-12 through VI-14). This site group contains 30 mainland sites with 28 on the inner shelf, and 1 each in bays/harbors and on the middle shelf (Table VI-8; Figure VI-14). Five species (all of Species Cluster A) occurred in more than 50% of the stations in Site Cluster 5 (Table VI-9; Appendix D-D10). The most frequently occurring species were speckled sanddab (93%), English sole (70%), and California sand star (60%; Table VI-9; Appendix D-D10). The most abundant species were speckled sanddab (3,283), California sand star (514), and Pacific sanddab (198; Appendix D-D11). Site Cluster 3 (Bays/Harbors/Central/South) included 16 stations at depths of 2-12 m (Table VI-8; Figures VI-12 through VI-14). This site group is formed by 16 mainland bay sites (Table VI-8; Figure VI-14). Five species occurred in more than 50% of the stations in Site Cluster 3, 4 of Species Cluster C and 1 of Species Cluster F (Table VI-9; Appendix D-D10). The most frequently occurring species were California halibut (88%), barred sand bass (69%), and round stingray and diamond turbot (56% each; Table VI-9, Appendix D10). The most abundant species were cobblestone seasquirt (598), mat mussel (508), and warty tunicate (198; Appendix D-D11). Species Clusters. Seven major species clusters were delineated by the analysis (Figure 12). The species clusters generally occupied different depth zones or combinations of these, each most abundant in one or more zone. The relationship of the site clusters with depth results from the depth distribution patterns of fish and invertebrate species found in the species clusters. All site clusters included representatives of two or more species groups. Species Cluster A was dominant in Site Clusters 6 and 9; Species Cluster B in Site Cluster 2; Species Cluster C in Site Cluster 3; Species Cluster D in Site Cluster 7; Species Cluster E in Site Cluster 1; Species Cluster F was most dominant in Site Cluster 4; and Species Clusters G in Site Cluster 9 (Figure VI-12). Species Cluster A included 31 species found primarily in Site Clusters 6 (Channel Islands Middle Shelf) and 9 Inner Shelf/Middle Shelf (Bays/Harbors South), but also to a lesser extent in other site clusters (Figure VI-12; Appendix D-D9 through D-D11). The most frequently occurring species in this group overall were Pacific sanddab (131 sites; 62% of 210), Dover sole (110; 52%), and hornyhead turbot (98; 47%) (Appendix D-D9). Twenty-nine species in the group occurred in 50% or more of the stations in at least one site cluster, with species occurring at this frequency in 1-5 site clusters (Table VI-9). Of these, the most widespread species of importance were Pacific sanddab and Dover sole, occurring at greater than 50% of stations in 5 site clusters (Site Clusters 1, 7, 6, 8, 9 for Pacific sanddab; Site Clusters 2, 1, 7, 6, 8 for Dover sole; Table VI-9). The most frequently occurring species of this group in a site cluster were Pacific sanddab (100% in Site Clusters 6, 8; Channel Islands Middle Shelf and Middle Shelf, respectively), and longspine combfish and Dover sole (100% each in Site Cluster 8, Middle Shelf). The most abundant species in the group overall were white sea urchin (33,028), Pacific sanddab (17,058), and speckled sanddab (6,785; Appendix D-D11). The most abundant species in a site cluster was white sea urchin with 17,465 in Site Cluster 6; 5,617 in Site Cluster 9; and 5,132 in Site Cluster 7 (Appendix D-D11). Table VI-8. Frequency of occurrence (number of stations) of combined demersal fish and megabenthic invertebrate site clusters by region and subpopulation on the southern California shelf and upper slope at depths of 2-476 m, July-October 2003. 
Figure VI-11a. Recurrent groups of combined demersal fishes and megabenthic invertebrates occurring at multiple sites on the southern California shelf at depths of 2-476 m, July-October 2003. Index of affinity (I.A.)=0.50. Group depths are numbered in order of depth. Species within a group are listed in order of abundance. Lines show relationships between groups and associates, with values indicating the proportion of possible pairs with I.A.=0.50. 
Figure VI-11b. Recurrent groups of combined demersal fishes and megabenthic invertebrates occurring at multiple sites on the southern California shelf at depths of 2-476 m, July-October 2003. Index of affinity (I.A.)=0.50. Group depths are numbered in order of depth. Species within a group are listed in order of abundance. Lines show relationships between groups and associates, with values indicating the proportion of possible pairs with I.A.=0.50. 
Figure VI-12. Summary of combined demersal fish and megabenthic invertebrate cluster analysis and relationships among site and species clusters on the southern California shelf at depths of 2-476 m, July-October 2003. 
Figure VI-13. Bathymetric distribution of demersal fish and megabenthic invertebrate site clusters on the southern California shelf at depths of 2-476 m, July-October 2003. Table VI-9. Frequency of occurrence (percent of stations) of demersal fish and megabenthic invertebrate species occurring at 50% or more of the stations in at least one site cluster on the southern California shelf and upper slope at depths of 2-476 m, July-October 2003. (See Appendix D-D10 for complete Species Cluster B percent occurrences). 
Species Cluster B included 18 species primarily from Site Cluster 2 sites (Upper Slope; Figure VI-12; Appendices Appendix D-D9 through D-D11). The most frequently occurring species in this group overall were northern heart urchin (29 sites; 14% of 210), and California heart urchin and unidentified sponge (26 sites; 12%, each; Appendix D-D9). Ten species in the group occurred in 50% or more of the stations in at least one site cluster, with species occurring at this frequency in 1-2 site clusters (Appendix D-D10). Of these, the most widespread species of importance was northern heart urchin, occurring at greater than 50% of stations in 2 site clusters (Site Clusters 2 and 1; Table VI-9; Appendix D-D10). The most frequently occurring species of this group in a site cluster were northern heart urchin (78% in Site Cluster 2), and bigfin eelpout and offshore blade shrimp (72% each in Site Cluster 2). The most abundant species in the group overall were northern heart urchin (36,074), the sea star Myxoderma platyacanthum (10,571), and the brittle star Asteronyx longifissus (9,172; Appendix D-D11). These three species were also the most abundant species in a site cluster (Site Cluster 2) with 28,938; 9,460; and 9,169, respectively (Appendix D-D11). Species Cluster C included 14 species found primarily in Site Cluster 3 (Bays/Harbors Central/South; Figure VI-12; Appendix D-D9 through D-D11). The most frequently occurring species in this group overall were barred sand bass (14 sites; 7% of 210), and diamond turbot and California aglaja (11 sites; 5% each; Appendix D-D9). Four species occurred in 50% or more of the stations in at least one site cluster, (Table VI-9; Appendix D-D10). The most frequently occurring species of this group in a site cluster were barred sand bass (69%), diamond turbot and round stingray (56% each), and California aglaja (50%), all in Site Cluster 3. The most abundant species in the group overall were cobblestone sea squirt (598), mat mussel (508), and warty tunicate (440; Appendix D-D11). These three species were also the most abundant species in Site Cluster 3 with the same respective abundances (Appendix D-D11). Species Cluster D included 19 species primarily dominant in Site Cluster 7 (Outer Shelf; Figure VI-12; Appendix D-D9 through D-D11). The most frequently occurring species in this group overall were spotted cusk-eel (31 sites; 15% of 210), greenstriped rockfish (29 sites; 14%), and armed box crab (21 sites; 10%; Appendix D-D9). Four species occurred in 50% or more of the stations in at least one site cluster (Table VI-9; Appendix D-D10). Shortspine combfish occurred at this level in 3 site clusters (1, 7, 6). Shortspine combfish was also the most frequently occurring species of this group in a site cluster (81% in Site Cluster 7, 80% in Site Cluster 1, and 76% in Site Cluster 6; Table VI-9). The most abundant species in the group overall were shortspine combfish (1,155), feather star (Florometra serratissima; 224), and white paperbubble (Philine alba; 188; Appendix D-D11). The most abundant species in a site cluster were shortspine combfish (432, Site Cluster 1; 412, Site Cluster 7), and feather star (202, Site Cluster 7; Appendix D-D11). Species Cluster E included 23 species which were dominant in Site Cluster 1 (Upper Slope/Outer Shelf; Figure VI-12; Appendix D-D9 through D-D11). The most frequently occurring species in this group overall were slender sole (56 sites; 27% of 210), eastern Pacific bobtail (52 sites; 25%), and fragile sea urchin and ridgeback rock shrimp (24 sites; 24% each; Appendix D-D9). Eleven species in the group occurred in 50% or more of the stations in at least one site cluster (Table VI-9; Appendix D-D10). Fragile sea urchin was most widespread, occurred at this level in 3 site clusters (1, 2, 7; Table VI-9). Slender sole was the most frequently occurring species of this group in a site cluster (100% in Site Cluster 1), followed by fragile sea urchin 92% and blacktip poacher (84%) also in Site Cluster 1 (Table VI-9). The most abundant species in the group overall were fragile sea urchin (20,917), northern heart urchin (8,568), and slender sole (4,559; Appendix D-D11). These were also the most abundant species in a site clusters, with fragile sea urchin 15,897 in Site Cluster 1, northern heart urchin 8,568 in Site Cluster 2, and slender sole (4,038 at Site Cluster 1; Appendix D-D11). Species Cluster F included 27 species which were most dominant in Site Cluster 4 (Inner Shelf/Bays/Harbors; Figure VI-12; Appendix D-D9 through D-D11). The most frequently occurring species in this group overall were New Zealand paperbubble (52 sites; 25% of 210), California halibut (45 sites; 21%), and California lizardfish (43 sites; 20%; Appendix D-D9). Six species in the group occurred in 50% or more of the stations in at least one site cluster (Table VI-9; Appendix D-D10). California halibut was the most frequently occurring species of this group in a site cluster (88% in Site Cluster 3, Bays/Harbors Central/South), followed by white croaker and queenfish (70 and 65%, respectively, in Site Cluster 4; Table VI-9). The most abundant species in the group overall were blackspotted bay shrimp (1,919), New Zealand paperbubble (881), and white croaker (856; Appendix D-D11). These were also the most abundant species in a site cluster (Site Cluster 4 in all casers), with blackspotted bay shrimp being 1,701, white croaker (839), and New Zealand paperbubble (438; Appendix D-D11). Species Cluster G included 35 species which were most dominant in Site Cluster 9 (Inner Shelf/Middle Shelf; Figure VI-12; Appendix D-D9 through D-D11). The most frequently occurring species in this group overall were yellow sea twig (41 sites; 20% of 210), California blade barnacle (30 sites; 14%), and California market squid (26 sites; 12%; Appendix D-D9). Three species in the group occurred in 50% or more of the stations in at least one site cluster (Table VI-9; Appendix D-D10). Pacific argentine (Argentina sialis) was the most frequently occurring species of this group in a site cluster (63% in Site Cluster 8, Middle Shelf), followed by rosy tritonia (52% in Site Cluster 6, Channel Islands Middle Shelf), and yellow sea twig (50$, Site Cluster 8; Table VI-9). The most abundant species in the group overall were yellow sea twig (1,577), California market squid (384), and shortbelly rockfish (338; Appendix D-D11). These were also the most abundant species in a site cluster, with yellow sea twig being 1,539 in Site Cluster 9, California market squid with 339 in Site Cluster 8, and shortbelly rockfish being 290 in Site Cluster 6 (Appendix D-D11). Directory: pub -> download pub -> Acm word Template for sig site pub -> The german unification, 1815-1870 pub -> Baltic Olympiads in Informatics: Challenges for Training Together pub -> Preparation of Papers for ieee transactions on medical imaging pub -> Forthcoming meetings and conferences pub -> Asilomar Conference on Circuits, Systems & Computers, Pacific Grove, ca, November 1978, pp. 55 58 pub -> Forthcoming meetings and conferences pub -> Harmonised compatibility and sharing conditions for video pmse in the 7 9 ghz frequency band, taking into account radar use Download 11.21 Mb. Share with your friends:
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