A food web including parasites for kelp forests of the Santa Barbara Channel, California

AbstractWe built a high-resolution topological food web for the kelp forests of the Santa Barbara Channel, California, USA that includes parasites and significantly improves resolution compared to previous webs. The 1,098 nodes and 21,956 links in the web describe an economically, socially, and ecologically vital system. Nodes are broken into life-stages, with 549 free-living life-stages (492 species from 21 Phyla) and 549 parasitic life-stages (450 species from 10 Phyla). Links represent three kinds of trophic interactions, with 9,352 predator-prey links, 2,733 parasite-host links and 9,871 predator-parasite links. All decisions for including nodes and links are documented, and extensive metadata in the node list allows users to filter the node list to suit their research questions. The kelp-forest food web is more species-rich than any other published food web with parasites, and it has the largest proportion of parasites. Our food web may be used to predict how kelp forests may respond to change, will advance our understanding of parasites in ecosystems, and fosters development of theory that incorporates large networks.

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Mechanisms leading to recruitment inhibition of giant kelp Macrocystis pyrifera by an understory alga

Marine Ecology Progress Series ◽

10.3354/meps13550 ◽

2021 ◽

Vol 657 ◽

pp. 59-71

Author(s):

BA Beckley ◽

MS Edwards

Keyword(s):

Field Experiments ◽

Local Community ◽

Kelp Forest ◽

Macrocystis Pyrifera ◽

Forest Recovery ◽

Kelp Forests ◽

Giant Kelp ◽

Combined Effects ◽

Life Stages ◽

Survival And Growth

The forest-forming giant kelp Macrocystis pyrifera and the communities it supports have been decreasing across their native ranges in many parts of the world. The sudden removal of giant kelp canopies by storms increases space and light for the colonization by understory macroalgae, such as Desmarestia herbacea, which can inhibit M. pyrifera recovery and alter local community composition. Understanding the mechanisms by which algae such as D. herbacea interact with M. pyrifera can provide insight into patterns of kelp forest recovery following these disturbances and can aid in predicting future community structure. This study experimentally tested the independent and combined effects of two likely competitive mechanisms by which D. herbacea might inhibit recovery of M. pyrifera in the Point Loma kelp forest in San Diego, California (USA). Specifically, we conducted field experiments to study the individual and combined effects of shade and scour by D. herbacea on the survival of M. pyrifera microscopic life stages, and the recruitment, survival, and growth of its young sporophytes. Our results show that scour had the strongest negative effect on the survival of M. pyrifera microscopic life stages and recruitment, but shade and scour both adversely affected survival and growth of these sporophytes as they grew larger. Canopy-removing storms are increasing in frequency and intensity, and this change could facilitate the rise of understory species, like D. herbacea, which might alter community succession and recovery of kelp forests.

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Parasites reduce food web robustness because they are sensitive to secondary extinction as illustrated by an invasive estuarine snail

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2008.0220 ◽

2009 ◽

Vol 364 (1524) ◽

pp. 1659-1663 ◽

Cited By ~ 39

Author(s):

Kevin D. Lafferty ◽

Armand M. Kuris

Keyword(s):

Food Web ◽

Trematode Species ◽

Snail Species ◽

Native Community ◽

Free Living ◽

Predator Prey ◽

Living Species ◽

Secondary Parasite ◽

Disproportionate Number ◽

Secondary Extinction

A robust food web is one in which few secondary extinctions occur after removing species. We investigated how parasites affected the robustness of the Carpinteria Salt Marsh food web by conducting random species removals and a hypothetical, but plausible, species invasion. Parasites were much more likely than free-living species to suffer secondary extinctions following the removal of a free-living species from the food web. For this reason, the food web was less robust with the inclusion of parasites. Removal of the horn snail, Cerithidea californica , resulted in a disproportionate number of secondary parasite extinctions. The exotic Japanese mud snail, Batillaria attramentaria , is the ecological analogue of the native California horn snail and can completely replace it following invasion. Owing to the similarities between the two snail species, the invasion had no effect on predator–prey interactions. However, because the native snail is host for 17 host-specific parasites, and the invader is host to only one, comparison of a food web that includes parasites showed significant effects of invasion on the native community. The hypothetical invasion also significantly reduced the connectance of the web because the loss of 17 native trematode species eliminated many links.

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Cryptic habitat use of white sharks in kelp forest revealed by animal-borne video

Biology Letters ◽

10.1098/rsbl.2019.0085 ◽

2019 ◽

Vol 15 (4) ◽

pp. 20190085 ◽

Cited By ~ 6

Author(s):

Oliver J. D. Jewell ◽

Adrian C. Gleiss ◽

Salvador J. Jorgensen ◽

Samantha Andrzejaczek ◽

Jerry H. Moxley ◽

...

Keyword(s):

Kelp Forest ◽

Video Data ◽

Kelp Forests ◽

Motion Sensing ◽

Predator Prey ◽

Habitat Features ◽

Fur Seals ◽

Cryptic Habitat ◽

Large Predators ◽

Marine Wildlife

Traditional forms of marine wildlife research are often restricted to coarse telemetry or surface-based observations, limiting information on fine-scale behaviours such as predator–prey events and interactions with habitat features. We use contemporary animal-attached cameras with motion sensing dataloggers, to reveal novel behaviours by white sharks, Carcharodon carcharias , within areas of kelp forest in South Africa. All white sharks tagged in this study spent time adjacent to kelp forests, with several moving throughout densely kelp-covered areas, navigating through channels and pushing directly through stipes and fronds. We found that activity and turning rates significantly increased within kelp forest. Over 28 h of video data revealed that white shark encounters with Cape fur seals, Arctocephalus pusillus pusillus , occurred exclusively within kelp forests, with seals displaying predator evasion behaviour during those encounters. Uniquely, we reveal the use of kelp forest habitat by white sharks, previously assumed inaccessible to these large predators.

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