Complex metacommunity structure for benthic invertebrates in a low‐diversity coastal system

Abstract

The majority of studies in metacommunity ecology have focused on systems other than marine benthic ecosystems, thereby providing an impetus to broaden the focus of metacommunity research to comprise marine systems. These systems are more open than many other systems and may thus exhibit relatively less discrete patterns in community structure across space. Metacommunity structure of soft‐sediment benthic invertebrates was examined using a fine‐grained (285 sites) data set collected during one summer across a large spatial extent (1700 km2). We applied the elements of metacommunity structure (EMS) approach, allowing multiple hypothesis of variation in community structure to be tested. We demonstrated several patterns associated with environmental variation and associated processes that could simultaneously assemble species to occur at the sites. A quasi‐Clementsian pattern was observed frequently, suggesting interdependent ecological relationships among species or similar response to an underlying environmental gradient across sites. A quasi‐nested clumped species loss pattern was also observed, which suggests nested habitat specialization. Species richness declined with depth (from 0.5 to 44.8 m). We argue that sensitive species may survive in shallower water, which are more stable with regard to oxygen conditions and present greater habitat complexity, in contrast to deeper waters, which may experience periodic disturbance due to hypoxia. Future studies should better integrate disturbance in terms of temporal dynamics and dispersal rates in the EMS approach. We highlight that shallow water sites may act as sources of recruitment to deeper water sites that are relatively more prone to periodic disturbances due to hypoxia. However, these shallow sites are not currently monitored and should be better prioritized in future conservation strategies in marine systems.

Sediment properties, biota, and local habitat structure explain variation in the erodibility of coastal sediments

“…In order to put our resuspension potential measures to a context, we converted our results of erosion threshold to critical friction velocities (1.96–2.84 cm s −1 for “muddy” sediments and 2.11–3.73 cm s −1 for “sandy” sediments). These values are in the same range as estimated friction velocities in previous studies from the area (1.25–3.58 cm s −1 , Valanko ). Hydrodynamic forcing in the study area is regulated by upwelling and wind‐wave events (Haapala ; Lehmann & Myrberg ) and previous studies have shown that resuspension is a frequent phenomenon in the area (Valanko et al ).…”

Species Sorting of Benthic Invertebrates in a Salinity Gradient – Importance of Dispersal Limitation

“…This together with the subsequent analyses of turnover and clumping in the EMS approach indicated a quasi-Clementsian structure [28] where partly overlapping distribution ranges of species shifted along this gradient indicating species sorting in the gradient. Such a pattern has recently been reported for invertebrates in other estuarine environments [26]. It cannot be ruled out, however, that some of the highly significant clumping is due to some truncation of the salinity gradient (see [28]) as the full gradient in the area, relevant for species with marine affinity, goes from > 30 to ca.…”

“…Then objective criteria based on coherence, turnover, and boundary clumping were used to assess the correspondence of the empirical data set with each of the hypothetical idealizations of species distribution ( i . e ., checkerboard, nested, evenly spaced, Gleasonian, or Clementsian patterns) [27,28,26]. …”

“…28 to 10 psu. The system likely differs functionally from other marine metacommunities, where local communities are embedded in gradients and the main dispersal barrier is the geographical distance between them [26]. In the present metacommunity the environmental gradient is represented by the different levels of the environmental factor in the areas of each local community, which are connected to each other via a large assumedly reasonably homogeneous open sea species pool.…”

Template for using biological trait groupings when exploring large‐scale variation in seafloor multifunctionality

“…For example, the variation in benthic community structure in our examined study area has been suggested to be a result of similar responses of species’ to an underlying environmental gradient across sites (Valanko et al. ). How trait modalities interact is an important avenue for new research.…”