Small burrowing amphipods cause major damage in a large kelp

Abstract

Large herbivores such as sea urchins and fish consume a high proportion of benthic primary production and frequently control the biomass of marine macrophytes. By contrast, small mesograzers, including gastropods and peracarid crustaceans, are abundant on seaweeds but have low per capita feeding rates and their impacts on marine macrophytes are difficult to predict. To quantify how mesograzers can affect macrophytes, we examined feeding damage by the herbivorous amphipods Sunamphitoe lessoniophila and Bircenna sp., which construct burrows in the stipes of subtidal individuals of the kelp Lessonia berteroana in northern-central Chile, southeast Pacific. Infested stipes showed a characteristic sequence of progressive tissue degeneration. The composition of the amphipod assemblages inside the burrows varied between the different stages of infestation of the burrows. Aggregations of grazers within burrows and microhabitat preference of the amphipods result in localized feeding, leading to stipe breakage and loss of substantial algal biomass. The estimated loss of biomass of single stipes varied between 1 and 77%. For the local kelp population, the amphipods caused an estimated loss of biomass of 24–44%. Consequently, small herbivores can cause considerable damage to large kelp species if their feeding activity is concentrated on structurally valuable algal tissue.

Temperate Kelp Forest Collapse by Fish Herbivory: A Detailed Demographic Study

“…In particular, herbivorous fish are recognized as important components of tropical assemblages, as they keep coral reefs free of canopy algae by reducing their competition (Bellwood et al, 2004;Steneck et al, 2017). In comparison, algae-consuming fishes have a limited presence in temperate latitudes (Meekan and Choat, 1997;Floeter et al, 2005), and invertebrate mesograzers in general, and sea urchins in particular, have often been considered one of the main causes of occasional kelp eradication in these regions (Estes and Palmisano, 1974;Dayton, 1975;Buschmann et al, 2004;Krumhansl and Scheibling, 2011;Filbee-Dexter and Scheibling, 2014;Ling et al, 2015;O'Brien and Scheibling, 2016;Gutow et al, 2020). However, both past (Choat, 1982;Andrew and Jones, 1990;Jones and Andrew, 1990) and more recent studies (Vergés et al, 2009;Taylor and Schiel, 2010;Basford et al, 2015;Steneck et al, 2017) show that herbivorous fish may also be important components on temperate reefs despite having less abundance and biomass than in low-latitudes (Holland et al, 2020).…”

Quantifying habitat provisioning at macroalgal cultivation sites

“…[77][78][79] Macroalgal epibionts such as endophytic or epiphytic algae, bryozoans, amphipods and hydroids may consume or degrade biomass, inhibit photosynthesis and algal growth, encourage grazers, increase disease susceptibility, contaminate commercial products by introducing allergen or toxin risks and damage farm infrastructure, thereby costing the aquaculture industry US$1.5-3 billion yr −1 . 12,40,76,[79][80][81][82][83][84][85][86][87][88] Farming infrastructure may also facilitate the settlement and spread of invasive non-native epibionts, by offering space for colonisation and reduced biotic resistance. 91 in turn benefitting shellfish growth, 92 enhancing primary production, 93,94 providing protection from predation, 95,96 encouraging settlement of commercially farmed shellfish 97,98 and mitigating for disease risk.…”

Whole System Analysis Is Required To Determine The Fate Of Macroalgal Carbon: A Systematic Review

“…Most quantification of the primary consumption of macroalgae occurs exclusively in a laboratory setting where consumers can be studied in detail (e.g., Ito et al 2019, Gilson et al 2021, which excluded these studies from review. Five studies were reviewed, however, which directly measured the loss of macroalgal biomass to herbivores in the field, with consumption rates (of grazers, detritivores, shredders, and others) defined in terms of both area and time (Itoh et al 2007, Krumhansl and Scheibling 2011b, Norderhaug and Christie 2011, Gutow et al 2020. These studies quantified the macroalgal carbon directed to primary consumption in the field by combining in situ measurements with either laboratory experiments or previous data sets.…”

“…For example, the stipe-burrowing herbivorous amphipods Sunamphitoe lessoniophila and Bircenna sp. were estimated to cause a maximum loss of 24-44% of biomass from the Lessonia berteroana kelp forests in northern-central Chile (Gutow et al 2020). Less dramatically, grazing rates of gastropod Lacuna vincta on Saccharina longicruris and Laminaria digitata in Nova Scotia were measured as a maximum of 1% and 1.5% of blade area respectively (Krumhansl and Scheibling 2011b).…”