Daily movement of the sea urchin Strongylocentrotus droebachiensis in different subtidal habitats in eastern Canada
نویسندگان
چکیده
We measured the movement and orientation of sea urchins at 2 sites in each of 4 habitats on urchin barrens in the northern Gulf of St. Lawrence, eastern Canada. We tagged the urchins measuring 25 to 70 mm in test diameter using a non-invasive technique involving a knot of fine monofilament thread tied around one spine. Smaller urchins (<25 mm) were tagged by tightening a loop around the test. Daily displacement increased markedly going from large juveniles (measuring 10–15 mm in diameter) to small adults (15–20 mm) and from small adults to large adults (>25–70 mm); however, no effect of size was detectable among large adults measuring from 25 to 70 mm. The increased movement with size was associated with a change in foraging, as gut analysis revealed a marked increase in the proportion of brown algae with increasing size. For large adults, the maximum net distance displaced per day varied among sites from 1.0 to 4.9 m d–1, and mean displacement varied from 0.40 (SE = 0.07) to 1.72 (SE = 0.28) m d–1. Distance moved also varied with habitat, and was greater in habitats that were further from kelp beds. Orientation was random and individuals showed frequent reverses in direction from day to day. Hunger state did not affect displacement, as there was no difference in distance moved between starved and fed urchins which were released in the barrens. However, urchins transplanted from kelp beds to the barrens were less active than urchins removed from and returned to the barrens. The shifts in movement with size are probably important in determining the size structure of urchins at different depths. The great distance covered by larger urchins as they move over open surfaces in search of favourable resources probably leads to their increased numbers in shallow habitats where food is abundant.
منابع مشابه
Acclimation and growth response of the green sea urchin Strongylocentrotus droebachiensis to fluctuating salinity
Sea urchins are osmoconformers and not typically found in euryhaline habitats. Yet the green sea urchin, Strongylocentrotus droebachiensis, is often found in areas periodically exposed to low salinity, e.g., near the mouths of rivers in the Gulf of Maine. These areas represent some of the most productive sea urchin fishing grounds in the northwestern Atlantic and are currently targeted for stoc...
متن کاملSpatial and temporal variation in growth of the green sea urchin, Strongylocentrotus droebachiensis, in
The green sea urchin, Strongylocentrotus droebachiensis, is found primarily in subtidal habitats but also occurs in low intertidal pools in the Gulf of Maine. Previous studies of low intertidal populations on Swans Island, Maine, USA, found that this species is slow growing and long lived. However, these population parameter estimates may not be representative because low intertidal pools are a...
متن کاملTrans-life cycle impacts of ocean acidification on the green sea urchin Strongylocentrotus droebachiensis Doctoral thesis
متن کامل
Effects of Oscillatory Flow on Fertilization in the Green Sea Urchin Strongylocentrotus droebachiensis
Broadcast spawning invertebrates that live in shallow, high-energy coastal habitats are subjected to oscillatory water motion that creates unsteady flow fields above the surface of animals. The frequency of the oscillatory fluctuations is driven by the wave period, which will influence the stability of local flow structures and may affect fertilization processes. Using an oscillatory water tunn...
متن کاملMethods for karyotyping and for localization of developmentally relevant genes on the chromosomes of the purple sea urchin, Strongylocentrotus purpuratus.
The purple sea urchin, Strongylocentrotus purpuratus, is the only non-chordate deuterostome model with a fully sequenced genome. Chromosomal localization of individual genes and resulting gene maps are unavailable for this or for any sea urchin. As a result, the purple sea urchin genome has not been mapped onto specific chromosomes and remains inaccessible to genome-wide approaches addressing q...
متن کامل