Seagrass Dynamics and Resilience

Connolly, Rod M.; Jackson, Emma L.; Macreadie, Peter I.; Maxwell, Paul; O’Brien, Katherine R.

doi:10.1007/978-3-319-71354-0_7

Cited by 7 publications

(6 citation statements)

References 54 publications

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“…Compared with seagrass beds of temperate regions worldwide, the genera Eualus, Heptacarpus, and Latreutes were the principally North Pacific caridean genera often abundant in Zostera meadows [42]. Crangon and Palaemon also dominated the decapod communities of seagrass beds in Western Port Bay, Australia [5,60]. Charybdis (Charybdis) japonica and Pu.…”

Section: Discussionmentioning

confidence: 99%

“…Seagrass beds have been shown to be highly productive marine habitats, common in estuarine and shallow marine coastal ecosystems throughout the world [1,2]. Among seagrass species, Zostera marina is widespread in temperate coastal areas of the Western Pacific, providing shelter for many marine animals, especially their juveniles [3][4][5][6]. Seagrass meadows' physical complexity also provides protection from predators [7][8][9] and allows coexistence of species occupying different ecological niches [10].…”

Section: Introductionmentioning

confidence: 99%

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Crustacean Decapod Assemblage Associated with Seagrass (Zostera marina) Beds in Southern Waters of Korea

Park

Kwak

Riedel³

2020

Diversity

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Decapod assemblages in Zostera marina beds from two bays adjacent to unvegetated habitats were investigated to assess their influence on decapod assemblages. Thirty-eight decapod species belonging to four taxa were collected using a small beam trawl at four habitat types from two different locations off the coast of Namhae Island, South Korea. Dominant decapod taxon at all habitats was the caridean shrimps, with Eualus leptognathus, Heptacarpus pandaloides, Latreutes anoplonyx, La. Laminirostris, and Palaemon macrodactylus being the most abundant caridean species. Crabs were characterized with the highest biomass, but with moderate species richness and abundance. Penaeoid and sergestoid shrimps only accounted for <1% of the total decapod abundance. The number of species and their abundance of decapod assemblages varied greatly by habitat type, season, and diel patterns, but not diversity. Species number and abundance peaked in seagrass beds of southern exposed bays during the autumn and were lowest in unvegetated habitats during the summer months. Diel decapod catch rates were higher at night. Dense seagrass vegetation and nighttime supported higher decapod mean densities, but not species richness and diversity. Multivariate analyses revealed that habitat type and season significantly affected the structure of decapod assemblages, but diel patterns had a minor influence. Among decapod species, Pa. macrodactylus and Pugettia quadridens characterized the decapod assemblages in seagrass beds at the northern semi-closed bay, while Telmessus acutidens, Crangon affinis, Cr. hakodatei, Charybdis (Charybdis) japonica, and Portunus sanguinolentus were significantly associated with both vegetated and unvegetated habitats at the southern exposed bay, with the former two species more abundant during the colder season.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Crustacean Decapod Assemblage Associated with Seagrass (Zostera marina) Beds in Southern Waters of Korea

Park

Kwak

Riedel³

2020

Diversity

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“…A broader meta-analysis across multiple species also found an overall positive relationship between genetic diversity and resilience ( Salo and Gustafsson, 2016 ). Given the ecological and evolutionary importance of genetic variation to resilience and a wide range of ecosystem services, it is crucial to understand how levels of genetic and genotypic diversity determine the response of natural populations to disturbance ( Unsworth et al, 2015 ; Connolly et al, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

Highly Disturbed Populations of Seagrass Show Increased Resilience but Lower Genotypic Diversity

et al. 2018

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The response of seagrass systems to a severe disturbance provides an opportunity to quantify the degree of resilience in different meadows, and subsequently to test whether there is a genetic basis to resilience. We used existing data on levels of long-standing disturbance from poor water quality, and the responses of seagrass (Zostera muelleri) after an extreme flood event in Moreton Bay, Queensland, Australia. Sites were grouped into high and low disturbance categories, in which seagrass showed high and low resilience, respectively, as determined by measuring rates of key feedback processes (nutrient removal, suppression of sediment resuspension, and algal grazing), and physiological and morphological traits. Theoretically, meadows with higher genotypic diversity would be expected to have greater resilience. However, because the more resilient meadows occur in areas historically exposed to high disturbance, the alternative is also possible, that selection will have resulted in a narrower, less diverse subset of genotypes than in less disturbed meadows. Levels of genotypic and genetic diversity (allelic richness) based on 11 microsatellite loci, were positively related (R2 = 0.58). Genotypic diversity was significantly lower at highly disturbed sites (R = 0.49) than at less disturbed sites (R = 0.61). Genotypic diversity also showed a negative trend with two morphological characteristics known to confer resilience on seagrass in Moreton Bay, leaf chlorophyll concentrations and seagrass biomass. Genetic diversity did not differ between disturbed and undisturbed sites. We postulate that the explanation for these results is historical selection for genotypes that confer protection against disturbance, reducing diversity in meadows that contemporarily show greater resilience.

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“…For all species, there is the possibility that recruitment pulses of new settled juveniles might have been missed by our sampling because juveniles settled briefly and then left the reef between our three survey periods, or alternatively, the whole year had poor recruitment rates. Given interannual variability in the strength of recruitment for some of the key harvested species in South Australia Vincent, compared to the patchy and much reduced extent of seagrass historically in Port Phillip Bay (Connolly et al, 2018), further supporting the above statement that the production at Glenelg may not be habitat limited and is instead subject to other bottlenecks, such as reduced egg supply. It is unlikely in this scenario that the age of the reef influenced juvenile densities, as Glenelg reef was constructed in the same years as Dromana (2020-2021; Margaret reef units installed between 2017 and 2020), and although some reef units at Glenelg are up to 5 years younger than at Margaret, other studies have shown that reef age is not an important variable in estimating the benefits of restoration (Hemraj et al, 2022).…”

Section: Number Of Species With Juvenile Density Greater On Reefmentioning

confidence: 71%

Estimating enhanced fish production on restored shellfish reefs using automated data collection from underwater videos

Connolly,

Herrera,

Rasmussen

et al. 2024

Journal of Applied Ecology

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Shellfish reefs across the world have been heavily degraded by mechanical harvesting, disease and declining water quality. In southern Australia, where substantial losses have occurred, government and non‐government efforts to restore functioning reefs are now underway with a strong focus on enhancing fish productivity. However, the capacity of these restored reefs to enhance fish production remains unknown, hampering estimates of return on investment. We quantify the density differences of newly recruited juvenile fish and other nekton on these restored reefs, relative to those on unrestored, unstructured habitat. Fish were surveyed at three paired reef‐unstructured locations using 169 unbaited stereo video deployments during three periods over 12 months (2022–2023). We used automation software, FishID, to automatically identify, size and count fish in videos. We subsequently applied known growth and mortality parameters to model enhancement of fish productivity. Sixteen species occurred as new recruits, with all but two found at higher densities on reefs than unstructured habitat. Enhancement of fish production from subtidal restored shellfish reefs from a single year's cohort is estimated to be, on average, 6186 kg ha−1 year−1 (SD 1802) after enough time has elapsed for all species to have matured. Species harvested commercially or recreationally contributed 98% of that production (6083 kg ha−1 year−1, SD 1797). Enhancement varied greatly among locations, ranging from 12,738 kg ha−1 year−1 (SD 2894), which is the highest yet recorded anywhere, to 1.4 kg ha−1 year−1 (SD 0.9). The lack of juvenile fish at the location with the lowest estimated enhancement might be explained by the impact of overfishing on recruitment of key species or by an abundance of alternative habitat for juvenile fish. Synthesis and applications. The combination of underwater videos with automated data extraction provides a reliable, cost‐effective method for surveying fish on oyster reefs. By quantifying enhanced fish productivity on reefs, we provide estimates that will underpin calculations of ecological, social and financial benefits, supporting the business case for scaling‐up restoration efforts.

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Seagrass Dynamics and Resilience

Cited by 7 publications

References 54 publications

Crustacean Decapod Assemblage Associated with Seagrass (Zostera marina) Beds in Southern Waters of Korea

Crustacean Decapod Assemblage Associated with Seagrass (Zostera marina) Beds in Southern Waters of Korea

Highly Disturbed Populations of Seagrass Show Increased Resilience but Lower Genotypic Diversity

Estimating enhanced fish production on restored shellfish reefs using automated data collection from underwater videos

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