Successional Mechanism Varies Along a Gradient in Hydrothermal Fluid Flux at Deep‐sea Vents

Abstract

Invertebrate communities inhabiting deep‐sea hydrothermal vents undergo substantial succession on time scales of months. Manipulative field experiments assessed the relative roles of environmental state and biotic interactions in determining temporal succession along a spatial gradient in vent fluid flux at three vent sites near 9°50′ N on the East Pacific Rise (2500 m water depth). Species colonization patterns on cubic basalt blocks (10 cm on a side) deployed by the submersible Alvin revealed both positive (facilitation) and negative (inhibition) biological interactions, in the context of established succession theory. Over a series of four cruises from 1994 to 1998, blocks were exposed to colonists for consecutive and continuous intervals in short‐term (5 + 8 = 13 mo) and longer‐term (8 + 29 = 37 mo) experiments. Colonists grouped into a mobile functional group were less abundant in the continuous interval (13 mo) than in the synchronous pooled‐consecutive intervals (5 + 8 mo) of the short‐term experiment, indicating that early colonists inhibited subsequent recruitment. Colonists grouped into a sessile functional group exhibited the opposite pattern, indicating facilitation. Similar trends, though not statistically significant, were observed in the longer‐term experiment. The character of species interactions varied along a gradient in hydrothermal fluid flux (and inferred productivity), with inhibitory interactions more prominent in zones with high temperatures, productivity, and faunal densities, and facilitative interactions appearing where temperatures, productivity, and densities were low. Analyses of primary succession on introduced basalt blocks suggest that biological interactions during early vent community development strongly modify initial patterns of settlement, even in the absence of sustained temporal change in the vent fluid flux. Corresponding Editor: R. J. Etter

Larvae from afar colonize deep-sea hydrothermal vents after a catastrophic eruption

“…The "warm" environment lacked tubeworms and had moderate flow with temperatures less than 7°C. These environments correspond respectively to the vestimentiferan and bivalve/suspension-feeder zones of previous studies at this site (35). In the 9°50′N region, species composition at different vents typically is similar within a zone, but varies substantially between zones (33,35,49).…”

“…Before the 2006 eruption, most 9°50′N vent sites hosted R. pachyptila, indicating a mid-to late stage of succession (16). Although changes in gastropod species composition also occur during succession at vents (34,35), no clear sequence of species replacement has been observed, and the pioneer gastropod colonists after the 1991 eruption did not include C. porifera or L. tevnianus (36). Deterministic succession is found in terrestrial meadows and temperate forests (28,37), both quite stable systems where disturbance time scales are long relative to species' generation times.…”

“…In the 9°50′N region, species composition at different vents typically is similar within a zone, but varies substantially between zones (33,35,49). Surfaces used to quantify pre-eruption colonists were selected from a larger sample set from this region of the EPR (35,49,50) (Fig. 1).…”

Community dynamics and ecosystem simplification in a high-CO 2 ocean

“…However, strong predictable species interactions can also cause succession to be canalized (32), in which disturbed assemblages converge on a predictable community over time (30,31,34). This pattern of predictable species interactions and canalized succession could be driven by harsh environmental conditions, such as ocean acidification, in which species that can tolerate or benefit from the extreme conditions are the only species that are able to persist through time (35,36). Whereas contingent succession promotes a patchy mosaic landscape, canalized succession promotes a homogenous landscape.…”

Expanding dispersal studies at hydrothermal vents through species identification of cryptic larval forms

“…Mullineaux et al 2003;Mullineaux 1 et al 2005;Adams and Mullineaux 2008;Matabos et al 2008a). Gastropod abundances 2 and ecological influence across the range of vent habitats make them key players in 3 structuring macrofaunal communities (e.g.…”