Temporal variability in phytodetritus and megabenthic activity at the seabed in the deep Northeast Atlantic
We report a ten-year study of the abundance and activity of megabenthos on the Porcupine Abyssal Plain, northeast Atlantic, together with observations on the occurrence of phytodetritus at the deep-sea floor (4850 m). Using the Southampton Oceanography Centre time-lapse camera system, 'Bathysna...
| Published in: | Progress in Oceanography |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2001
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| Subjects: | |
| Online Access: | https://pure.uhi.ac.uk/en/publications/e2eee669-9db3-43ba-a184-d9cd3980c3f4 https://doi.org/10.1016/S0079-6611(01)00066-0 |
| Summary: | We report a ten-year study of the abundance and activity of megabenthos on the Porcupine Abyssal Plain, northeast Atlantic, together with observations on the occurrence of phytodetritus at the deep-sea floor (4850 m). Using the Southampton Oceanography Centre time-lapse camera system, 'Bathysnap', we have recorded a radical change in the abundance and activity of megabenthos between the two periods of study (1991-1994 and 1997-2000). In 1991-1994, the larger megabenthos occurred at an abundance of c. 71.6/ha and were dominated by large holothurians. In addition, there were very substantial populations of smaller megabenthic ophiuroids (c. 4979/ha). Together, the total megabenthos are estimated to track over some 17 cm(2)/m(2)/d (exploiting 100% of the surface of the seabed in c. 2.5 years). In 1997-2000, the larger megabenthos increased to an abundance of c. 204/ha and were joined by exceptional numbers of a small holothurian species (Amperima rosea, 6457/ha) and ophiuroids (principally Ophiocten hastatum, 53,539/ha). The total megabenthos population was tracking at an estimnated rate of c. 247 cm(2)/m(2)/d (exploiting 100% of seabed in just 6 weeks). Coincident with these increases in the abundance and activity of the megabenthos, there were apparently no mass depositions of aggregated phytodetritus to the seabed in the summers of 1997-1999. Mass occurrences of phytodetritus had been noted during the summer months of the three years previously studied ( 1991, 1993 and 1994), with covering between 50 and 96% of the sediment surface. There is a statistically significant (p |
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