Decline of flounder (Platichthys flesus (L.)) at the margin of the species' distribution range

Jokinen, Henri; Wennhage, Håkan; Lappalainen, Antti; Ådjers, Kaj; Rask, Martti; Norkko, Alf

doi:10.1016/j.seares.2015.08.001

Cited by 21 publications

(28 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Salinity in this study was only represented as a component of cod reproductive volume, as in an earlier EwE model of the Baltic other salinity effects had little impact on model dynamics (Niiranen et al, 2013). However, salinity is considered a major determinant of present and future species distributions in the Baltic Sea (Gogina and Zettler, 2010;Ojaveer et al, 2010;Jokinen et al, 2015;Vuorinen et al, 2015). Oxygen conditions on the seafloor do not only affect the benthic communities through permanent low oxygen concentrations, but also through occasional extreme hypoxic events.…”

Section: Discussionmentioning

confidence: 95%

Combined Effects of Environmental Drivers on Marine Trophic Groups – A Systematic Model Comparison

2019

View full text Add to dashboard Cite

The responses of food webs to simultaneous changes in several environmental drivers are still poorly understood. As a contribution to filling this knowledge gap, we investigated the major pathways through which two interlinked environmental drivers, eutrophication and climate, affect the biomass and community composition of fish and benthic macrofauna. For this aim, we conducted a systematic sensitivity analysis using two models simulating the dynamics of benthic and pelagic food webs in the Baltic Sea. We varied environmental forcing representing primary productivity, oxygen conditions and water temperature in all possible combinations, over a range representative of expected changes during the 21st century. Both models indicated that increased primary productivity leads to biomass increase in all parts of the system, however, counteracted by expanding hypoxia. Effects of temperature were complex, but generally small compared to the other drivers. Similarities across models give confidence in the main results, but we also found differences due to different representations of the food web in the two models. While both models predicted a shift in benthic community composition toward an increased abundance of Limecola (Macoma) balthica with increasing productivity, the effects on deposit-feeding and predatory benthic groups depended on the presence of fish predators in the model. The model results indicate that nutrient loads are a stronger driver of change for ecosystem functions in the Baltic Sea than climate change, but it is important to consider the combined effects of these drivers for proper management of the marine environment.

show abstract

Section: Discussionmentioning

confidence: 95%

Combined Effects of Environmental Drivers on Marine Trophic Groups – A Systematic Model Comparison

2019

View full text Add to dashboard Cite

show abstract

“…When comparing the flounder landings from the GoF (ICES, 2017) to the proportion of P. flesus in the GoF samples, there is an almost perfect concordance between the two (Figure 3), so that landings were higher at times when the proportion of P. flesus in the GoF was higher, and the abrupt decline in landings closely matches in time the shift from a P. flesus-dominated to P. solemdali-dominated flounder assemblage. 1970 1971 1977 1 978 1986 1987 1997 1998 1998 1973 1975 19771978 1979 1986 1987 1997 1998 2006 2007 GoF as well as with a sharp decline in flounder CPUE in fishery-independent Finnish coastal fish surveys between 1975 and 1995 (Jokinen et al, 2015). Since salinity in the GoF is too low for P. flesus reproduction even under the most favorable conditions (Nissling et al, 2002), these findings suggest that either larval supply or juvenile and adult spillover from southern populations may have been important factors in shaping flounder abundance in the GoF.…”

Section: Re Sultsmentioning

confidence: 99%

“…The most dramatic decline in landings took place in the GoF: In the early 1980s, more than 1,000 t/y were landed, whereas in the last ten years, landings averaged below 100 t/y (ICES, 2017). While there are some doubts on how reliable catch estimates in the 1980s were, particularly from the USSR, catch per unit effort (CPUE) data from fish surveys on the Finnish coast confirm a decrease of over 60% from 1975 to 1995, and over 90% decrease from 1975 to 2012 (Jokinen et al, 2015), suggesting that the temporal decline in landings was not entirely a reflection of inaccurate reporting or lower fishing effort. Momigliano et al (2018Momigliano et al ( , 2017b) discovered that P. flesus can, in fact, be found at low density throughout the NBP (including the AS) and the GoF, and that they do not interbreed with P. solemdali (both studies found no evidence of hybridization in >300 individuals sampled throughout the Baltic Sea).…”

Section: Introductionmentioning

confidence: 99%

Cryptic temporal changes in stock composition explain the decline of a flounder (Platichthys spp.) assemblage

Momigliano

Jokinen

Calboli

et al. 2019

Evolutionary Applications

Self Cite

View full text Add to dashboard Cite

Unobserved diversity, such as undetected genetic structure or the presence of cryptic species, is of concern for the conservation and management of global biodiversity in the face of threatening anthropogenic processes. For instance, unobserved diversity can lead to overestimation of maximum sustainable yields and therefore to overharvesting of the more vulnerable stock components within unrecognized mixed‐stock fisheries. We used DNA from archival (otolith) samples to reconstruct the temporal (1976–2011) genetic makeup of two mixed‐stock flounder fisheries in the Åland Sea (AS) and the Gulf of Finland (GoF). Both fisheries have hitherto been managed as a single stock of European flounders ( Platichthys flesus ), but were recently revealed to target two closely related species: the pelagic‐spawning P. flesus and the newly described, demersal‐spawning P. solemdali . While the AS and GoF fisheries were assumed to consist exclusively of P. solemdali , P. flesus dominated the GoF flounder assemblage (87% of total) in 1983, had disappeared (0%) by 1993, and remained in low proportions (10%–11%) thereafter. In the AS, P. solemdali dominated throughout the sampling period (>70%), and P. flesus remained in very low proportions after 1983. The disappearance of P. flesus from the GoF coincides in time with a dramatic (~60%) decline in commercial landings and worsening environmental conditions in P. flesus’ northernmost spawning ground, the Eastern Gotland Basin, in the preceding 4–6 years. These results are compatible with the hypothesis that P. flesus in the GoF is a sink population relying on larval subsidies from southern spawning grounds and the cause of their disappearance is a cessation of larval supply. Our results highlight the importance of uncovering unobserved genetic diversity and studying spatiotemporal changes in the relative contribution of different stock components, as well as the underlying environmental causes, to manage marine resources in the age of rapid anthropogenic change.

show abstract

“…Current management assumes that in some of the International Council for the Exploration of the Sea subdivisions of the Baltic Sea (SD 27, and SD29-32, Figure 1A), only demersal flounders occur (ICES, 2017), though recent results from Momigliano et al (2017a) and Hinrichsen et al (2016) suggest that both SD 32 and SD 29 are likely to receive migrant pelagic flounders from southern spawning grounds. Secondly, in some regions of the Baltic Sea (particularly in the Finnish coast, SD 32) flounders have declined, possibly as a result of reduced larval supply and changes in environmental conditions in nursery areas (Jokinen et al, 2015(Jokinen et al, , 2016. To understand the drivers of the decline and to make future predictions, knowledge of species identities and stock composition is imperative.…”

Section: Introductionmentioning

confidence: 99%

Platichthys solemdali sp. nov. (Actinopterygii, Pleuronectiformes): A New Flounder Species From the Baltic Sea

et al. 2018

Self Cite

View full text Add to dashboard Cite

The European flounder Platichthys flesus (Linnaeus, 1758) displays two contrasting reproductive behaviors in the Baltic Sea: offshore spawning of pelagic eggs and coastal spawning of demersal eggs, a behavior observed exclusively in the Baltic Sea. Previous studies showed marked differences in behavioral, physiological, and life-history traits of flounders with pelagic and demersal eggs. Furthermore, a recent study demonstrated that flounders with pelagic and demersal eggs represent two reproductively isolated, parapatric species arising from two distinct colonization events from the same ancestral population. Using morphological data we first established that the syntypes on which the original description of P. flesus was based belong to the pelagic-spawning lineage. We then used a combination of morphological and physiological characters as well as genome-wide genetic data to describe flounders with demersal eggs as a new species:Platichthys solemdali sp. nov. The new species can be clearly distinguished from P. flesus based on egg morphology, egg and sperm physiology as well as via population genetic and phylogenetic analyses. While the two species do show some minor morphological differences in the number of anal and dorsal fin rays, no external morphological feature can be used to unambiguously identify individuals to species. Therefore, we developed a simple molecular diagnostic test able to unambiguously distinguish P. solemdali from P. flesus with a single PCR reaction, a tool that should be useful to fishery scientists and managers, as well as to ecologists studying these species.

show abstract

Decline of flounder (Platichthys flesus (L.)) at the margin of the species' distribution range

Cited by 21 publications

References 47 publications

Combined Effects of Environmental Drivers on Marine Trophic Groups – A Systematic Model Comparison

Combined Effects of Environmental Drivers on Marine Trophic Groups – A Systematic Model Comparison

Cryptic temporal changes in stock composition explain the decline of a flounder (Platichthys spp.) assemblage

Platichthys solemdali sp. nov. (Actinopterygii, Pleuronectiformes): A New Flounder Species From the Baltic Sea

Contact Info

Product

Resources

About