Juvenile Dungeness crabs () selectively integrate and modify the fatty acids of their experimental diets.

Dungeness crabs () are ecologically and economically important in the coastal Northeast Pacific, yet relatively little is currently known about their feeding behaviour in the wild or their natural diet. Trophic biomarkers, such as fatty acids (FA), can be used to reveal trophic interactions. We used two feeding experiments to assess differences in FA composition of juvenile crabs fed different known foods to evaluate how they modify and integrate dietary FA into their own tissues and determine whether crab FA reflect diet changes over a six-week period.

Surf-zone hydrodynamics alter phytoplankton subsidies affecting reproductive output and growth of tidal filter feeders.

Surf zones, classified from reflective to dissipative, separate the ocean from shore and subsidies from the coastal ocean must pass through surf zones to reach the shore. We have observed that variations in phytoplankton concentrations in the water over the intertidal zone varied with surf-zone hydrodynamics and we hypothesized that this variation would alter growth rates, population structure, and reproductive output of Mytilus californianus and Balanus glandula. From May 2016 to April 2017, along 7 km of Cape Arago, Oregon, USA surf-zone phytoplankton concentrations were determined weekly at nine sites with varying surf-zone hydrodynamics as indicated by surf-zone widths.

Planktonic Subsidies to Surf-Zone and Intertidal Communities.

Plankton are transported onshore, providing subsidies of food and new recruits to surf-zone and intertidal communities. The transport of plankton to the surf zone is influenced by wind, wave, and tidal forcing, and whether they enter the surf zone depends on alongshore variation in surf-zone hydrodynamics caused by the interaction of breaking waves with coastal morphology. Areas with gently sloping shores and wide surf zones typically have orders-of-magnitude-higher concentrations of plankton in the surf zone and dense larval settlement in intertidal communities because of the presence of bathymetric rip currents, which are absent in areas with steep shores and narrow surf zones.

Variation in the abundance of Pseudo-nitzschia and domoic acid with surf zone type.

Most harmful algal blooms (HAB) originate away from the shore and, for them to endanger human health, they must be first transported to shore after which they must enter the surf zone where they can be feed upon by filter feeders. The last step in this sequence, entrance into the surf zone, depends on surf zone hydrodynamics. During two 30-day periods, we sampled Pseudo-nitzschia and particulate domoic acid (pDA) in and offshore of a more dissipative surf zone at Sand City, California (2010) and sampled Pseudo-nitzschia in and out of reflective surf zones at a beach and rocky shores at Carmel River State Beach, California (2011).

Surfzone hydrodynamics as a key determinant of spatial variation in rocky intertidal communities.

Larvae of intertidal species develop at sea and must return to adult habitats to replenish populations. Similarly, nutrients, detritus and plankton provide important subsidies spurring growth and reproduction of macroalgae and filter-feeding invertebrates that form the foundation of intertidal communities. Together, these factors determine the density and intensity of interactions among community members.

Does fish larval dispersal differ between high and low latitudes?

Several factors lead to expectations that the scale of larval dispersal and population connectivity of marine animals differs with latitude. We examine this expectation for demersal shorefishes, including relevant mechanisms, assumptions and evidence. We explore latitudinal differences in (i) biological (e.

Pelagic larval duration and dispersal distance revisited.

I present dispersal distances for 44 species with data on propagule duration (PD) for 40 of these. Data were combined with those in Shanks et al. (2003; Ecol.

Recruitment limitation in Dungeness crab populations is driven by variation in atmospheric forcing.

Ecologists have long debated the relative importance of biotic interactions vs. abiotic forces on the population dynamics of both marine and terrestrial organisms. Investigation of stock size in Dungeness crab (Cancer magister) is a classic example of this debate.

Adding teeth to wave action: the destructive effects of wave-borne rocks on intertidal organisms.

Observations in rocky intertidal areas demonstrate that breaking waves 'throw' rocks and cobbles and that these missiles can damage and kill organisms. Targets in the intertidal were dented by impacts from wave-borne rocks. New dents/day in these targets was positively correlated with the daily maximum significant wave height and with new patches/day in aggregations of the barnacle Chthamalus fissus.