Resource specialisation among suspension-feeding invertebrates on rock walls in Fiordland, New Zealand, is driven by water column structure and feeding mode

Leichter

et al. 2018

Global Change Biology

Organic matter produced by the sea ice microbial community (SIMCo) is an important link between sea ice dynamics and secondary production in near-shore food webs of Antarctica. Sea ice conditions in McMurdo Sound were quantified from time series of MODIS satellite images for Sept. 1 through Feb. 28 of 2007-2015. A predictable sea ice persistence gradient along the length of the Sound and evidence for a distinct change in sea ice dynamics in 2011 were observed. We used stable isotope analysis (δ C and δ N) of SIMCo, suspended particulate organic matter (SPOM) and shallow water (10-20 m) macroinvertebrates to reveal patterns in trophic structure of, and incorporation of organic matter from SIMCo into, benthic communities at eight sites distributed along the sea ice persistence gradient. Mass-balance analysis revealed distinct trophic architecture among communities and large fluxes of SIMCo into the near-shore food web, with the estimates ranging from 2 to 84% of organic matter derived from SIMCo for individual species. Analysis of patterns in density, and biomass of macroinvertebrate communities among sites allowed us to model net incorporation of organic matter from SIMCo, in terms of biomass per unit area (g/m ), into benthic communities. Here, organic matter derived from SIMCo supported 39 to 71 per cent of total biomass. Furthermore, for six species, we observed declines in contribution of SIMCo between years with persistent sea ice (2008-2009) and years with extensive sea ice breakout (2012-2015). Our data demonstrate the vital role of SIMCo in ecosystem function in Antarctica and strong linkages between sea ice dynamics and near-shore secondary productivity. These results have important implications for our understanding of how benthic communities will respond to changes in sea ice dynamics associated with climate change and highlight the important role of shallow water macroinvertebrate communities as sentinels of change for the Antarctic marine ecosystem.

Section: Methodsmentioning

confidence: 99%

Section: Macroinvertebrate Densitymentioning

confidence: 99%

Contribution of sea ice microbial production to Antarctic benthic communities is driven by sea ice dynamics and composition of functional guilds

Leichter

et al. 2018

Global Change Biology

“…This topographic isolation results in a persistent low salinity layer, and likely an isolated circulation pattern in the inner fjord, limiting larval dispersal (Perrin et al 2004). Rock wall habitats contain a relatively low diversity of suspension feeding invertebrates with brachiopods and tubeworms as dominant space occupiers (Smith 2001, Wing andJack 2012). There are very low densities of macroalgae, and no significant beds of the common kelp Ecklonia radiata (Wing et al 2007).…”

Section: Discussionmentioning

confidence: 99%

A safety network against regional population collapse: mature subpopulations in refuges distributed across the landscape

Jack

2013

Ecosphere

Citation: Jack, L., and S. R. Wing. 2013. A safety network against regional population collapse: mature subpopulations in refuges distributed across the landscape. Ecosphere 4(5):57. http://dx.doi.org/10.1890/ES12-00221.1Abstract. Theory suggests that marine reserve networks can maintain wide geographical distributions of exploited fish and invertebrates. Since 2005, ten regions in southwest New Zealand have been designated no-take marine reserves nested within eleven commercial fishing exclusion zones. We observed increases in abundance of rock lobster (Jasus edwardsii ) and blue cod (Parapercis colias) from 2002-2010 within some marine reserves, but not in the other management zones. Mature size distributions of rock lobsters were only observed within protected areas. Model based inference ranked environmental descriptors versus area under protection in explaining abundance and changes in abundance observed within marine reserves and indicated that J. edwardsii became most abundant in larger marine reserves, but only under specific environmental conditions. P. colias became most abundant in large marine reserves, particularly those with larger buffers against commercial fishing. Analysis of population changes for both species across Fiordland since implementation of the reserve network (2006)(2007)(2008)(2009)(2010) indicated that marine reserves resulted in either increases in, or maintenance of abundance in the face of regional declines. We highlight the potential effectiveness of networks of marine reserves in maintaining subpopulations with high abundance and mature size structure across large geographical areas, particularly if key criteria are incorporated.

“…Genetic structure of this long-lived (> 300 yr) species demonstrated a nonequilibrium population with short distance larval dispersal following a relatively recent colonisation (Miller 1997(Miller , 1998. Antipathella fiordensis feed on zooplankton and represent an ecological link between pelagic productivity and the benthic community (Wing & Jack 2012). Patterns in invertebrate biodiversity were strongly influenced by gradients in productivity maintained by physical processes along the axes of the fjord basins (Smith 1998).…”

Section: Primary Productivitymentioning

confidence: 99%

Fiordland: the ecological basis for ecosystem management

New Zealand Journal of Marine and Freshwater Research

Jack

2014

Self Cite

Marine ecosystems are structured by physical and biological influences on: production and transport of organic matter; population dynamics; and food web architecture. Here, we review how scientific insights in the Fiordland marine area have supported ecosystem management. Fiordland is a case study for four ecological paradigms: 1. physical forcing of productivity; 2. subsidies of organic matter; 3. reproductive source-sink dynamics; and 4. stability of food web architecture. Understanding of these processes underpinned development of a network of marine reserves comprising the first regional experiment in marine ecosystem management for New Zealand. Monitoring the marine reserves demonstrated increasing abundance of rock lobsters (Jasus edwardsii) and blue cod (Parapercis colias). Further, analyses of reef fish communities indicated reserves supported abundant high trophic level omnivores, leading to stable communities and intact food webs. These results demonstrated success in two of the objectives of ecosystem management-enhanced production of exploited species and preservation of biodiversity.