Urchin grazing of kelp gametophytes in warming oceans Veenhof, Reina J.; Coleman, Melinda A.; Champion, Curtis ...
Journal of phycology,
October 2023, 2023-Oct, 2023-10-00, 20231001, Letnik:
59, Številka:
5
Journal Article
Recenzirano
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Sea urchins can cause extensive damage to kelp forests, and their overgrazing can create extensive barren areas, leading to a loss of biodiversity. Barrens may persist when the recruitment of kelp, ...which occurs through the microscopic haploid gametophyte stage, is suppressed. However, the ecology of kelp gametophytes is poorly understood, and here we investigate if grazing by juvenile urchins on kelp gametophytes can suppress kelp recruitment and if this is exacerbated by climate change. We compared grazing of Ecklonia radiata gametophytes by two species of juvenile urchins, the tropical Tripneustes gratilla and the temperate Centrostephanus rodgersii, at winter (19°C), summer (23°C), and ocean warming (26°C) temperatures for the low‐latitude range edge of E. radiata, which is vulnerable to ocean warming. We examined the rate of recovery of gametophytes following grazing and determined whether they survived and formed sporophytes after ingestion by sea urchins. Both T. gratilla and C. rodgersii grazed E. radiata gametophytes, reducing their abundance compared to no grazing controls. Surprisingly, temperature did not influence grazing rates, but gametophytes did not recover from grazing in the ocean warming (26°C) treatment. Gametophytes survived ingestion by both species of sea urchin and formed sporophytes after ingestion by T. gratilla, but not C. rodgersii. These results suggest complex grazer–gametophyte interactions, in which both negative (reduced abundance and poor recovery with warming) and positive (facilitated recruitment) effects are possible. Small grazers may play a more important role in kelp ecosystem function than previously thought and should be considered in our understanding of alternate stable states.
Arabinogalactan proteins are a diverse group of cell wall-associated proteoglycans. While structural and molecular genetic analyses have contributed to the emerging improved understanding of the ...wide-range of biological processes in which AGPs are implicated; the ability to detect, localize, and quantify them is fundamentally important. This chapter describes three methods: histological staining, radial gel diffusion, and colorimetric quantification, each of which utilize the ability of Yariv reagent to bind to AGPs.
Marine kelp forests cover 1/3 of our world's coastlines, are heralded as a nature-based solution to address socio-environmental issues, connect hundreds of millions of people with the ocean, and ...support a rich web of biodiversity throughout our oceans. But they are increasingly threatened with some areas reporting over 90% declines in kelp forest cover in living memory. Despite their importance and the threats they face, kelp forests are entirely absent from the international conservation dialogue. No international laws, policies, or targets focus on kelp forests and very few countries consider them in their national policy. The Kelp Forest Challenge addresses that gap. Together with 252 kelp experts, professionals, and citizens from 25 countries, the Kelp Forest Challenge was developed as a grassroots vision of what the world can achieve for kelp forest conservation. It is a global call to restore 1 million and protect 3 million hectares of kelp forests by 2040. This is a monumental challenge, that will require coordination across multiple levels of society and the mobilization of immense resources. Pledges may therefore include area for protection or restoration, enabling pledges which assist in conservation (funding, equipment, professional expertise, capacity building), or awareness-based pledges which increase awareness or education about kelp forests. Correspondingly, participants may be from government, scientific institutions, private sector, NGOs, community groups, or individuals. This challenge is the beginning of a 17-year mission to save our kelp forests and anyone and any organisation is invited to participate.
Kelp forests are economically important ecosystems that support a wealth of biodiversity but are declining globally. They are often replaced by biologically depauperate alternate stable states ...dominated by turfing algae. Hysteresis maintains algal turfs by inhibiting kelp recruitment, preventing the reestablishment of kelp forests. The mechanisms inhibiting kelp recruitment remain poorly understood as microscopic stages of kelp are difficult to study
in situ
. A potential mechanism contributing to the suppression of recruitment may be turf-facilitated grazing of kelp gametophytes, the haploid free-living reproductive life stage. Here we assess the resilience of kelp gametophytes to grazing pressure from a gastropod micrograzer commonly present in turf under current and future ocean warming scenarios. Gametophyte coverage and abundance were significantly reduced following grazing under all temperatures, however there was no significant effect of temperature on grazing rates. Once grazing pressure was removed, gametophyte abundance recovered to control levels, but the total coverage and length of gametophytes continued to decline in all treatments. Gametophytes were found to survive micrograzer ingestion and continued to grow in aggregations in the gastropod’s mucus trail and faeces, even producing sporophytes. Gametophyte survival post-ingestion may positively contribute to dispersal and sporophyte recruitment, however the lack of gametophyte recovery at elevated temperatures may counteract this effect under future ocean warming. Taken together, this study demonstrates complex interactions that take place in the turf micro-habitat of kelp gametophytes and highlights biotic factors influencing transitions between kelp forests and algal turfs.
Kelp Gametophytes in Changing Oceans Veenhof, Reina J.; Champion, Curtis; Dworjanyn, Symon A. ...
CRC Press eBooks,
2022, Letnik:
60
Book Chapter
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Kelp forests are ecologically diverse habitats that provide vast ecosystem goods and services, but are threatened by climate and anthropogenic stressors. Laminarian kelps have an alternating biphasic ...life cycle, and while there is a growing understanding of climate impacts on the macroscopic diploid sporophyte, impacts on the microscopic haploid gametophyte stage are just emerging. There exists a strong history of gametophyte literature on single species and environmental factors, but only recently studies have increasingly examined multiple climate stressors, species and populations. We synthesize studies on kelp gametophytes, building upon our understanding of their responses to environmental conditions and subsequent vulnerability in changing oceans. Kelp gametophytes have a broad tolerance to environmental conditions predicted to change with climate change, including temperature and irradiance, but large variation exists among species and populations. Key processes such as gametogenesis and early sporophyte development consistently appear more sensitive to environmental conditions than vegetative growth and may present bottlenecks to ongoing kelp persistence. Indirect effects of climate change negatively affect kelp gametophytes through competition, grazing and sedimentation. Modern genomic techniques are paving the way to transition research into field settings that include both sporophyte and gametophyte stages. Unravelling the response of gametophytes to changing environmental conditions is beginning to provide an understanding of overall kelp forest persistence and enables proactive conservation and management initiatives in changing oceans.
This chapter presents a contemporary synthesis of how kelp gametophytes are influenced by variation in environmental conditions relevant to anthropogenic climatic change, indirect effects of climate change such as change of ecological interactions and other anthropogenic disturbances such as pollution and eutrophication and the implications for kelp persistence. Kelp forests are ecologically diverse habitats that provide vast ecosystem goods and services, but are threatened by climate and anthropogenic stressors. Laminarian kelps have an alternating biphasic life cycle, and while there is a growing understanding of climate impacts on the macroscopic diploid sporophyte, impacts on the microscopic haploid gametophyte stage are just emerging. Modern genomic techniques are paving the way to transition research into field settings that include both sporophyte and gametophyte stages. Unravelling the response of gametophytes to changing environmental conditions is beginning to provide an understanding of overall kelp forest persistence and enables proactive conservation and management initiatives in changing oceans.
