Food limitation in cockles ( Cerastoderma edule (L.)): Influences of location on tidal flat and of nearby presence of mussel beds

Environmental change, such as variation in upwelling intensity and consequent variation in marine primary productivity, may have profound effects on organisms. In the fossil record, morphological variation within lineages may be explained by environmental changes, although it is often difficult to establish a causal relationship between morphological and environmental change. Size and shape change were quantified in suspension-feeding turritellid gastropods from the Pleistocene and Recent of Chile, wherein both temporal and geographic patterns of variation were found. Upwelling and productivity conditions were reconstructed from a variety of published sources, including information on diatom, foraminiferan, and coccolithophore diversity and abundance, organic carbon burial, percent carbonate, and phosphorite deposition. In addition, carbon and oxygen stable isotope ratios from turritellid shell material were analyzed in order to determine temperature and productivity conditions. Comparison of results from the morphological analysis to upwelling/productivity reconstructions indicates that wider whorl shape and larger shell size are associated with more intense upwelling. Increases in the amount of shell material secreted may be explained by increased availability of food associated with stronger upwelling. This interpretation is consistent with observations of increased shell growth recorded for modern, non-turritellid mollusks. This type of analysis may help to establish causation for certain kinds of morphological evolution observed in the fossil record of turritellids and other suspension-feeding gastropods.

A model of clearance rate regulation in mussels

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 466:35-41 (2012) - DOI: https://doi.org/10.3354/meps09938 Benthic disturbance affects intertidal food web dynamics: implications for investigations of ecosystem functioning Christopher P. Cesar1,2,*, Chris L. J. Frid1 1School of Environmental Sciences, University of Liverpool, Brownlow Street, Liverpool L69 3GP, UK 2Present address: APEM, Riverview, A17 Embankment Business Park, Heaton Mersey, Stockport SK4 3GN, UK *Email: christopher_p_cesar@yahoo.co.uk ABSTRACT: Analysis of biological traits within assemblages is increasingly used as a proxy for ecological functioning. However, taxa often show plasticity in the expression of traits and can potentially change trait expression depending on local conditions. While many forms of disturbance will lead to changes in the species composition of the assemblage, small-scale disturbances can trigger alterations in the behaviour of taxa and hence the ecological roles they are delivering. Such changes would not be detected by biological traits analysis (BTA) alone. BTA therefore has the potential to misinform as to the contribution of assemblages to ecological processes. To assess the potential for taxa to change their expression of traits, the feeding modes of 8 taxa from 2 intertidal assemblages in north-west England, UK, were investigated using stable isotope analyses following experimental sediment disturbance and removal of cockles Cerastoderma edule. Two of the 8 taxa exhibited significant changes to their isotopic composition within disturbed plots. Short-term plastic changes to food web dynamics following changes in environmental conditions have implications for the suitability of BTA as a tool for investigating ecosystem function. Although BTA provides much insight into the ecological roles of taxa within systems and can be extremely effective at identifying changes associated with different assemblage compositions, it is conceivable that changes to ecological functioning may be undetected by BTA alone, and hence there is the need for this approach to be supported by experimental observation. KEY WORDS: Trait plasticity · Ecosystem function · Anthropogenic impact · Biological traits analysis · BTA Full text in pdf format PreviousNextCite this article as: Cesar CP, Frid CLJ (2012) Benthic disturbance affects intertidal food web dynamics: implications for investigations of ecosystem functioning. Mar Ecol Prog Ser 466:35-41. https://doi.org/10.3354/meps09938 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 466. Online publication date: October 15, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

The estimation of DEB parameters for various Northeast Atlantic bivalve species

The population biology of the bivalve Cerastoderma edule was studied by monthly sampling from April 1994 to September 1995 at Neuharlingersieler Nacken, a backbarrier tidal flat near Spiekeroog island (East Frisian Wadden Sea, North Sea). Four stations located along a tidal gradient from 56 to 80% immersion time were established in order to analyse cockle growth, mortality and production. The highest densities were recorded at the beginning of the study (1000-1250 ind. M-2) with an intense and progressive decrease through 1995. A spatial distribution pattern was observed during summer 1994, with juveniles (3-12 mm long) being found in the high intertidal whereas adults occurred along the middle and lower intertidal. Based on growth increment data from tagging-recapture experiments, the parameters of the von Bertalanffy growth curve were estimated to be: asymptotic length L??= 40 mm, and growth constant K = 0.404 y-1. A growth ring was formed in summer (July-August 1994). Annual somatic production ranged between 38.16 and 59.33 g AFDW . m-2. y-1. Total mortality ranged between Z = 0.52 year-1 and Z = 3.03 year-1. The distribution of the population was affected by passive displacements of juvenile cockles from the upper part of the intertidal toward lower zones in combination with high mortality at the station farthest from the coast, probably resulting from mussels overlying.

Mass mortalities in bivalve populations: A review of the edible cockle Cerastoderma edule (L.)

Increasing evidence shows that spatial interactions between sedentary organisms can structure communities and promote landscape complexity in many ecosystems. Here we tested the hypothesis that reef-forming mussels (Mytilus edulis L.), a dominant intertidal ecosystem engineer in the Wadden Sea, promote abundances of the burrowing bivalve Cerastoderma edule L. (cockle) in neighboring habitats at relatively long distances coastward from mussel beds. Field surveys within and around three mussel beds showed a peak in cockle densities at 50-100 m toward the coast from the mussel bed, while cockle abundances elsewhere in the study area were very low. Field transplantation of cockles showed higher survival of young cockles (2-3 years old) and increased spat fall coastward of the mussel bed compared to within the bed and to areas without mussels, whereas growth decreased within and coastward of the mussel bed. Our measurements suggest that the observed spatial patterns in cockle numbers resulted from (1) inhibition effects by the mussels close to the beds due to preemptive algal depletion and deteriorated sediment conditions and (2) facilitation effects by the mussels farther away from the beds due to reduction of wave energy. Our results imply that these spatial, scale-dependent interactions between reef-forming ecosystem engineers and surrounding communities of sedentary benthic organisms can be an important determinant of the large-scale community structure in intertidal ecosystems. Understanding this interplay between neighboring communities of sedentary species is therefore essential for effective conservation and restoration of soft-bottom intertidal communities.

To investigate the relationship between stock size and production of an entire feeding guild, and in particular to find out whether this relationship is dome-shaped (showing an optimal abundance for production), we used a 40 yr data set of the 3 most important suspension-feeding bivalves (Cerastoderma edule, Mytilus edulis, and Mya arenaria) in a Wadden Sea tidal flat area (about 20 km2). The data set contained data on numerical density of individuals, annual rates of weight growth, recruitment, survival, and secondary production. At higher densities (>400 ind. m-2), we found reductions of growth rate and recruitment. At the highest densities, the reduction in weight growth was so strong that production was lower than its maximal values at intermediate densities. This optimal density of around 400 ind. m-2 was considered to represent the carrying capacity of the system for suspension-feeding bivalves. High densities resulting in reduced production, however, rarely (in only 5% of the years) occurred over the 40 yr monitoring period. Clear bottom-up limitation of bivalve production was thus very unusual in the studied area. Year-to-year variation in growth and production of suspension-feeding bivalves were not related to chlorophyll concentrations in the main tidal stream and did not follow the declining long-term trends of primary production and chlorophyll concentrations. The main conclusion of the paper is that production increases with stock size, but only to a certain threshold value that is rarely reached as a consequence of recruitment being curtailed by a top-down process (predation on young stages).

Abstract. Three successive years of recruitment failure, intensive fishery, and high rates of natural mortality eliminated all intertidal mussel beds and nearly all cockle beds from the Dutch Wadden Sea in the course of 1990. In late 1990 and early 1991, zoobenthic biomass and particularly bivalve stocks were unprecedentedly low. The following unusual events were noted: Relatively high diatom and chlorophyll concentrations in the autumn of 1990 and an exceptionally early and dense spring bloom of diatoms in March 1991; Exceptionally early onset of rapid growth in the bivalve Macoma balthica in March 1991; Above‐average weights of the soft parts of bivalves in the 1990/91 winter; Elevated mortality rates in bivalves that could serve as alternative prey for birds specialised on big bivalves (oystercatchers and eiders); Signs of food shortage in such birds: high mortality rates and emigration to other feeding areas; A rapid recovery of the benthos started in the summer of 1991, accelerated by an exceptionally high recruitment in some of the affected species. It is concluded that the Wadden Sea ecosystem responded in an elastic way to the removal of two of its key species. The events are not seen as merely coincidental but are regarded as a chain of causes and effects.

In the late 1970s food supply to herbivores suddenly doubled in the western half of the Dutch Wadden Sea probably as a consequence of increased nutrient concentrations. The response of zoobenthos was studied during 1970–1990 as part of a long‐term monitoring program, including annual sampling at 15 fixed stations with very different environmental conditions (elevation, sediment grain size) on Balgtand, a 50‐km2 tidal flat area. The total zoobenthic stock in the affected area roughly doubled within 2 yr after the doubling of the stock of planktonic algae. However, the magnitude of the response differed from station to station. We tested the hypothesis that a strong positive response would occur particularly at stations where food could be limiting, i.e. where zoobenthic food demand was high relative to food supply. Biomass increases of zoobenthos in the order of a doubling were indeed restricted to the part of Balgzand characterized already in the 1970s by high biomass values. The zoobenthic biomass hardly increased in two areas of Balgzand with relatively low values for zoobenthic biomass and species richness. In these impoverished areas environmental conditions are harsh and the benthic communities are dominated by small opportunistic species. One of these areas is characterized by a high intertidal elevation (short daily inundation periods) combined with a sheltered location near the coast (resulting in muddy sediments), the other by severe exposure to currents and wind (rasultinh in mobile sands with silt and organic‐matter contents) due to its offshore position. We conclude that food limitation only existed in the midshore communities living under relatively mild abiotic conditions. Apparently, the benthic consumer populations benefitted from eutrophication‐induced enhancement of their food supply by enlargement of their stocks only where they were not too stressed by unfavorable abiotic conditions.