Intertidal Zone

I am co-planning a conference on "Shipwrecks in the Intertidal Zone", dealing with this topic from different angles: The archaeology and site formation of the wreck sites, the historical narratives connected to the wrecks in terms of crews, wreckers and beachcombers, and last not least the public interest in these sites, channelled through volunteer involvement like site monitoring and museum exhibitions.

We have already received very interesting international papers from Saint-Pierre-et-Miquelon to Auckland, and are now in the progress of finalising the programme in order to raise funding for this conference.

If you are working on a wreck in the intertidal zone, please contact me. Although we have almost completed the programme for oral presentations, we are still seeking contributions for our digital poster presentation, which shall be integrated as slideshow-loop during the coffee breaks (like an "intermission"), also to be broadcasted as live conference. 

Contact: d.zwick@archaeologia-navalis.org

Diversity and distribution of gastropod species have been studied during pre-monsoon season in the intertidal zones of two sampling sites i.e., Rushikonda beach and Tenneti park from Visakhapatnam coast. Each site was surveyed during low tide levels of pre-monsoon season. Total of 38 species, 20 genera and 12 families were identified during the survey. Diversity indices were utilized to quantify the species richness and evenness. The highest number of individuals were observed in Tenneti park than Rushikonda. A significant change is observed in the total number of individuals collected from month wise in the pre-monsoon season. The highest number of individuals belonged to 3 families, Neritidae, Littorinidae, Cerithidae. The result of this study indicates that the coast of Visakhapatnam has huge gastropod fauna and needs to be protected.

Barnacles grow on every hard surface within Puget Sound’s intertidal zones, including on other barnacles. And
as barnacles accumulate, one upon another, often many generations deep, a rich and varied biologic community
develops around them.
Barnacle-based communities are diverse, densely populated, colorful, active, and otherwise wonderful. They
are, with respect to those attributes, comparable to coral reef ecosystems. Unlike coral reefs, there is a very real
limit to the size (depth, thickness, horizontal distribution) of barnacle aggregations.
We examine the larger of the two common Puget Sound acorn barnacles, Semibalanus cariosus, for characteristics
that may explain their critical role in these thriving communities. We also look for details that may explain the
limit to their ‘success’ as reef-builders.
In this report we look at common barnacles more closely than other observers might, but not with the formality
of professional marine biologists. We do our best to present our observations in a way that will encourage your
participation in ‘Accessible Sciences’.

Physico-chemical parameters and macrobenthic invertebrates of the intertidal zone of Gusa, Cagayan de Oro City, Philippines were assessed from March to May 2014. Water temperature, pH, salinity, dissolved oxygen, biological oxygen demand, and type of substrate were determined in the study were within the normal range. A modified transect-quadrat method was used in an approximately 14,000 m of study area. Seven hundred twenty seven individuals belonging to 15 species were found in the area. These organisms belong to four phyla namely: Mollusca, Arthropoda, Echinodermata, and Annelida. The three most abundant organisms found were Coenobita clypeatus, Ophiothrix longipeda, and Cypraea poraria with relative abundance of 73.86%, 4.13% and 3.71% respectively. Most of the macrobenthic fauna identified exhibited a clumped pattern of distribution, while the rest are randomly distributed. The species diversity of the area is 1.19 which is very low compared to reports from related studies.

During an annual cycle, flux rates of oxygen, nitrate, nitrite, ammonium, phosphate and silicate were measured in light and dark bell jars at three sites in Ria Formosa (Algarve, Portugal) enclosing either a natural macrophytic community (macroalgae on sand or mud, a seagrass bed of Zostera noltii) or bare sediments. The results are compared with a preceeding study in which the same bell jar technique has been applied in the Sylt-Rømø Bay of the northern Wadden Sea. Nitrate flux was mainly directed from the water column to the benthic communities in Ria Formosa, as well as in the Sylt-Rømø Bay. However, nitrate uptake was higher in the northern, more eutrophic study area. In Ria Formosa, nutrient concentrations were lower than in the Sylt-Rømø Bay possibly due to strong water exchange with Atlantic waters. High temperatures and strong insolation had a greater impact on nitrate fluxes in Ria Formosa than in the Sylt-Rømø Bay. Bioturbating macrofauna increased ammonium efflux in the Sylt- Rømø Bay while this effect was not as pronounced in the Ria Formosa study sites. Benthic phosphate uptake dominated in the Ria Formosa and was correlated to initial phosphate concentrations in incoming waters. At both study sites, oxygen and nutrient fluxes were correlated with temperature. Additionally, flux rates were strongly influenced by biotic components and levels of eutrophication. A literature survey showed that mainly in temperate regions, material fluxes increase with temperature, whereas in warmer areas, ammonium and phosphate fluxes between sediment and water were generally lower.

Features of an intertidal population of Chondracanthus teedei var. lusitanicus, which occurs in sandy basins on rocky shores of part of the Portuguese coast (Buarcos, Figueira da Foz), were studied over one year. Biomass and plant size showed a small increase in early spring (April), a marked increase in early summer (June/July) and were at a minimum in late summer. There was generally more tetrasporophytes (4–32.5%) than female gametophytes (3–29%), which contrasts with other geographical regions where C. teedei populations have been studied, such as Brazil and France. However, non-fructified thalli predominated throughout the year. Phycocolloid extracts were compared for the various stages using spectroscopic methods (FTIR, FT-Raman, 1H- and 13C-NMR). These showed a hybrid carrageenan belonging to the lambda family in the tetrasporophyte and a hybrid kappa-iota-mu-nu carrageenan in the female gametophyte and non-fructified thalli. The average phycocolloid content was 34.9% dry weight, with a maximum of 43.6% in July. The combination of high available biomass and phycocolloid content makes this species a potentially important source of kappa/iota hybrid carrageenan in Portugal additional to the traditionally harvested carrageenophytes.

Competition for limiting resources drives animal aggression. Aggression in hermit crabs has been well studied in shell acquisition circumstances, yet less is known about hermit crabs’ competitive behavior in other contexts, especially as they relate to feeding. As active foragers, competition for food resources may be a major determinant of hermit crab aggression and fighting behavior, particularly in intertidal marine environments, where protein-rich carrion may be limiting. Here, we measured aggressive, competitive interactions between hermit crabs
[Pagurus samuelis (Stimpson, 1857)] that were presented with carrion in the laboratory, immediately after they were collected from the field. Aggregations of three crabs were provided with either mussel or gastropod flesh. Both forms of carrion naturally indicate food availability, though only the latter may correlate with potential shell availability. We
found that levels of aggression rose significantly in response to both carrion conditions, but not in response to a control condition involving the introduction of a non-eatable object. Larger individuals displayed the highest levels of aggressive behavior, but levels of aggression did not differ between crabs provided with the gastropod and the mussel flesh. These results reveal that food—independent of a shell resource—
can be a powerful motivator for competitive behavior in hermit crabs. Further studies of food-related aggression between different hermit crab species could shed light on how interspecific competition might lead to potential specializations on different carrion or prey resources.

The hitherto undescribed terrestrial fauna of small arthropods (mites) from the intertidal zone of the sea coasts of Cebu is studied in this paper. Thirteen species of mites are described and presented by means of line drawings and scanning electron microscopy (SEM). An outline of the biology of the appropriate systematic groups is given and the littoral environment is also taken into account. No comparable investigations from this region have been conducted before, hence this paper.

This study performs a morphological and molecular characterization of the species belonging to the genus Aulactinia from Mar del Plata (Argentina), previously identified as A. marplatensis and A. reynaudi. The great similarity in the natural history of these species, and our results on external and internal anatomy, clearly suggests that the sea anemones of the genus Aulactinia inhabiting the studied areas must be considered a single species, A. marplatensis. The molecular data provided here further support this assertion: all the individuals of A. marplatensis and A. reynaudi appear together intermixed in a monophyletic group clearly distinct from the outgroup species A. incubans and A. verrucosa. We have also completed the description of A. marplatensis, adding more anatomical features based mainly on internal anatomy and cnidae.

Following heavy winter storms and sedimentation in 1993,Spartina foliosa (Pacific cordgrass) clones established on a 6.5-ha mudflat in Tijuana Estuary, with over 80 new clones counted by 1997. El Niño Southern Oscillation (ENSO) storms in 1993 apparently facilitated the habitat conversion through river flooding, which caused a temporary reduction in soil salinity and delivered large volumes of sediment. Extreme sedimentation likely raised mudflat elevations enough to allowSpartina establishment. We hypothesized that clones, once established, increased sedimentation in a positive feedback loop leading to accelerated habitat conversion. We collected data on elevation,Spartina expansion, and sediment accretion in two consecutive years (1998–1999). The elevation range of the mudflats in 1998 (0.5–0.83 m NGVD) was within the elevation range ofSpartina at this site (0.39–0.83 m NGVD), indicating that remaining mudflats are at elevations suitable for further expansion. Sediment accretion ranged from 4.0–12.7 cm between 1997–1998 (ENSO conditions), but was close to long-term averages (˜ cm yr−1) in 1998–1999 (nonflood year) indicating how susceptible Tijuana Estuary is to sedimentation from episodic storms. Although accretion rates were similar withinSpartina clones and on bare mudflats over the ENSO winter, clones were typically dome-shaped suggesting higher sediment retention rates within clones. The radial expansion rates of clones (1.31±0.25 m in 1998; 1.12±0.07 m in 1999) approximated the maxima reported for this species and were not related to clone size or vigor. Conditions on the mudflat appear ideal forSpartina growth, masking differences that might otherwise be observed. Given the likelihood of sedimentation-driven habitat conversion in southern California and other Mediterranean-type estuaries, management efforts are needed to address sedimentation issues on a watershed scale. We recommend that wetland restoration projects in southern California include large areas of intertidal mudflat, both to maintain habitat for shorebird feeding and to allow colonization by salt marsh vegetation.

... There appears to be little or no change in δ 13 C or δ 15 N during decay in the seagrasses Zostera noltii (Machás et al., 2006), Thalassia testudinum and Zostera marina ([Zieman et al., 1984], [Stephenson et al., 1986] and [Fenton and Ritz, 1988]) or the mangrove Rhizophora ...

This paper introduces a method for temporal studies of steep rocky intertidal communities. It combines the use of digital image technology with field methodology, so that a wide area of the community can be sampled in a short time. Two current nondestructive percent cover estimation methods (visual estimation and point intersection) were compared in terms of cost, operational advantages and data quality, with a proposed method for a sucessional study . The proposed method used sequential photos to sample multiple fixed vertical transects over time. Reproduction of the mid-intertidal transect over time was possible by overlaying temporal transects in an image editing program. This method was similar to the point intersection quadrat method used to estimate percent cover. Benefits included reduced time on field work, economic advantages and other advantages of using digital photography, such as recording. Temporal photography of transects provided measurements of recruitment, mortalit...