The roles of flowering, overwinter survival and sea surface temperature in the long-term population dynamics of Zostera marina around the Isles of Scilly, UK
Abstract:Interaction between biotic and abiotic drivers of dynamics is an important topic in ecology. Despite numerous short-term studies, there is a paucity of evidence about how environmental structure modifies dynamics in marine systems. We quantified Zostera marina flowering and non-flowering shoot density annually from 1996 to 2012 around the Isles of Scilly, UK, parameterizing a population dynamic model. Flowering is structured in time and space, with temperature and flowering positively associated at some locati… Show more
“…As flowering plants, seagrasses can reproduce both sexually, through flowering, and asexually, via rhizome extension. Flowering was to be positively associated with seagrass cover the following year, at the same sampling sites as the current study 43 . Our results corroborate this finding and do not consistently indicate any disruption to the mating system in declining sites.…”
Section: Discussionsupporting
confidence: 55%
“…The over-arching aim of this study was to quantify population genetic structure of a relatively isolated and fragmented seagrass population. We undertook this at a location that has been under long-term ecological monitoring, and which is known to be suffering localised declines 11,43,50 . By presenting these findings, we hoped to establish baseline information on genetic diversity and motivate future research into possible causal links between population genetics and abundance trajectories.…”
In isolated or declining populations, viability may be compromised further by loss of genetic diversity. Therefore, it is important to understand the relationship between long-term ecological trajectories and population genetic structure. However, opportunities to combine these types of data are rare, especially in natural systems. Using an existing panel of 15 microsatellites, we estimated allelic diversity in seagrass, Zostera marina, at five sites around the Isles of Scilly Special Area of Conservation, UK, in 2010 and compared this to 23 years of annual ecological monitoring (1996–2018). We found low diversity and long-term declines in abundance in this relatively pristine but isolated location. Inclusion of the snapshot of genotypic, but less-so genetic, diversity improved prediction of abundance trajectories; however, this was spatial scale-dependent. Selection of the appropriate level of genetic organization and spatial scale for monitoring is, therefore, important to identify drivers of eco-evolutionary dynamics. This has implications for the use of population genetic information in conservation, management, and spatial planning.
“…As flowering plants, seagrasses can reproduce both sexually, through flowering, and asexually, via rhizome extension. Flowering was to be positively associated with seagrass cover the following year, at the same sampling sites as the current study 43 . Our results corroborate this finding and do not consistently indicate any disruption to the mating system in declining sites.…”
Section: Discussionsupporting
confidence: 55%
“…The over-arching aim of this study was to quantify population genetic structure of a relatively isolated and fragmented seagrass population. We undertook this at a location that has been under long-term ecological monitoring, and which is known to be suffering localised declines 11,43,50 . By presenting these findings, we hoped to establish baseline information on genetic diversity and motivate future research into possible causal links between population genetics and abundance trajectories.…”
In isolated or declining populations, viability may be compromised further by loss of genetic diversity. Therefore, it is important to understand the relationship between long-term ecological trajectories and population genetic structure. However, opportunities to combine these types of data are rare, especially in natural systems. Using an existing panel of 15 microsatellites, we estimated allelic diversity in seagrass, Zostera marina, at five sites around the Isles of Scilly Special Area of Conservation, UK, in 2010 and compared this to 23 years of annual ecological monitoring (1996–2018). We found low diversity and long-term declines in abundance in this relatively pristine but isolated location. Inclusion of the snapshot of genotypic, but less-so genetic, diversity improved prediction of abundance trajectories; however, this was spatial scale-dependent. Selection of the appropriate level of genetic organization and spatial scale for monitoring is, therefore, important to identify drivers of eco-evolutionary dynamics. This has implications for the use of population genetic information in conservation, management, and spatial planning.
“…The study also highlights the presence of some healthy seagrass meadows, but these are far from large human populations (Isles of Scilly and Mannin Bay, Ireland). Long-term ecological data from the Isles of Scilly seagrass confirm the relatively healthy status of these systems [ 26 ].…”
Section: Discussionmentioning
confidence: 99%
“…Importantly, there is little way of using the data to act as an early warning of future loss. Only the data collected within the Isles of Scilly monitoring programme presents information pertinent to understanding the status of the system as it is a long-term study that provides detailed data of shoot morphology, density, disease and epiphytic data [ 26 ].…”
Seagrass ecosystems face widespread threat from reduced water quality, coastal development and poor land use. In recent decades, their distribution has declined rapidly, and in the British Isles, this loss is thought to have been extensive. Given increasing knowledge of how these ecosystems support fisheries production, the understanding of their potential rapid loss, and the difficulty in restoring them, it is vital we develop an understanding of the risks they are under, so that management actions can be developed accordingly. Developing an understanding of their environmental status and condition is therefore critical to their long-term management. This study provided, to our knowledge, the first examination of the environmental health of seagrass meadows around the British Isles. This study used a bioindicator approach and involved collecting data on seagrass density and morphology alongside analysis of leaf biochemistry. Our study provides, to the best of our knowledge, the first strong quantitative evidence that seagrass meadows of the British Isles are mostly in poor condition in comparison with global averages, with tissue nitrogen levels 75% higher than global values. Such poor status places their long-term resilience in doubt. Elemental nutrient concentrations and morphological change suggest conditions of excess nitrogen and probable low light, placing many of the meadows sampled in a perilous state, although others, situated away from human populations were perceived to be healthy. Although some sites were of a high environmental health, all sites were considered at risk from anthropogenic impacts, particularly poor water quality and boating-based disturbances. The findings of this study provide a warning of the need to take action, with respect to water quality and disturbance, to prevent the further loss and degradation of these systems across the British Isles.
“…We monitored five seagrass ( Z. marina ) meadows around the Isles of Scilly, UK ( figure 1 and table 1 ) from 1996 to 2014, using rigorous and consistent methodology [ 34 , 42 , 43 ]. Figure 1.…”
Section: Field Survey and Aerial Photography Of Seagrass Meadowsmentioning
Measurement of population persistence is a long-standing problem in ecology; in particular, whether it is possible to gain insights into persistence without long time-series. Fractal measurements of spatial patterns, such as the Korcak exponent or boundary dimension, have been proposed as indicators of the persistence of underlying dynamics. Here we explore under what conditions a predictive relationship between fractal measures and persistence exists. We combine theoretical arguments with an aerial snapshot and time series from a long-term study of seagrass. For this form of vegetative growth, we find that the expected relationship between the Korcak exponent and persistence is evident at survey sites where the population return rate can be measured. This highlights a limitation of the use of power-law patch-size distributions and other indicators based on spatial snapshots. Moreover, our numeric simulations show that for a single species and a range of environmental conditions that the Korcak–persistence relationship provides a link between temporal dynamics and spatial pattern; however, this relationship is specific to demographic factors, so we cannot use this methodology to compare between species.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
