Algal Adaptations to Benthos

ALGAL ADAPTATIONS TO BENTHOS

INTRODUCTION

Benthic algae are aquatic algae that cover the hard bottoms of the seafloor; they are a large source of food and energy for many organisms. These organisms are the hotspot of biodiversity and also major participants in the food webs (Berov et al., 2017). Different species adapt to different depths of the ocean and sometimes are pushed by competition of other organisms into peripheral zones which control the species composition further down in the ocean thus, controlling the biological factors. The marine benthic class has acquired during the course of evolution a number of interesting characteristics such as adaptations to reduced light availability, physical disturbances, acidification and also climate change. These adaptions are critical in order for the survival and continuation of these aquatic organisms. Many challenges are presented to the marine environment because the seawater in which they live experience variations in temperature and salinity but also have a dramatic change of pressure with depth. Green alga is mostly seen in the higher parts of the shore and the brown algae are located in the lower part of the coastline but the shallower portion of the sea. All these species occur at various distances in the ocean. The brown algae are the largest and most conspicuous group of organisms, also known as kelp. Many species of animals and algae are able to thrive in between large kelp and also sometimes live on the kelp branches.

BACKGROUND

Benthic algae are needed for the survival of other animals and to continue the life cycle of other species beneath the seafloor, they are also the dominant primary producers of many shallow streams and lakes. In many ways benthic algal effect the daily nutrients organisms are receiving and temperate exposure whether good or bad that potentially impact algal growth and community composition (Fricke et al., 2018). It has been largely reported that this unique marine organism inhabits firm substrates in the euphotic region and also form some of the greatest diverse and useful aquatic ecosystems (Berov et al., 2018). Majority of the algae that form from benthos are plant like organisms that come in a range of varied shapes, colors, and sizes. Several of the most common algae that are seen in benthic ecosystems in some streams or lakes are Chamaesiphon polonicus, Hildenbrandia rivularis , Ulothrix zonata; these are just some of the more usual species seen in cyanobacteria, red algae, and green algae (Cantonati et al., 2012).

PHYSICAL DISTURBANCE

Like all plants, algae possess many adaptations to flooding that are usually organized into two primary categories which are anatomical-morphological and biochemical-physiological. These classes of adaptations are important for the plants survive in disturbed environments.

Waves are a common physical disturbance among benthic algae, Achnanthidium dolomiticum is one example of an epiphytic diatom that has adapted to these water level fluctuations reducing the physical stress of the water motion (Cantonati and Lowe 2014). Water abuse is thoroughly increasing because of the demand for water and also climate change is limiting the water availability which all take part in the oscillations of water (Cantonati and Lowe 2014). These small or major floods limit the colonization and development of the benthic algae effected by the stream or other materials on the seafloor (Townsend et al., 2005).  The physical forces imposed by the moving water apply a critical need for adaptions throughout these species. The species Cystoseira bosphorica having a dominant presence in shallow areas of some coastal zones around the world which has given escalation to the modifications of the species to be able to resist direct wave control by partaking in a very strong and adaptable thalli (Berov et al., 2017).

LIGHT

Sunlight typically cannot reach below a certain amount of feet in the ocean which prevents benthic algae in both micro and macro growth on the deep-sea floor, this is due to significantly less food sources. Light availability is the most significant limiting issue for primary production by the benthic marine flora. These organisms are competing for solar radiation not only within the algae community but also with the other organisms in the ecosystem. Light becomes saturated in very clear waters or when water levels are highest and exposed to the atmosphere causing detrimental effects on algae. The assembly and storage of the UVA absorbing pigment scytonemin which confers UV protection in episodes of high irradiation in the sheath of alga is one of the many passive defense mechanisms used for marine algae (Cantonati and Lowe 2014). Another adaptation to light that algae have to acquire is light restrictive distributions. Rhodophytes or red alga also live in shockingly deep water and excel in dim lights. These organisms have a complicated but unique accessory pigment that absorb and transfer adequate light energy to control photosynthetic activity at extreme distances. Jaoa bullata is a type of green alga that has siphonoxanthin, a carotenoid with an absorption maximum in the blue-green portion of the spectrum that exceeds in deep waters or shielded regions (Cantonati and Lowe 2014). Another macroalgal formed in low light is the species Phyllophora cripsa, it grows on rigid substrates and the unattached forms grow on sandy and shell sediments (Berov et al., 2017). In the shallow zone disturbance factors are considered the most important, however the mid-depth and deep zones are considered steadier and the deep zone is disturbed by dangerous light reduction (Cantonati and Lowe 2014).

CLIMATE CHANGE

Temperatures driven by climate change rise is known to substitute the growth of marine organisms, fluctuating their distribution ranges and allowing them to reside in new habitats (Fricke et al.,). Climate change is progressively increasing the duration of droughts and non-flow periods in streams and rivers around the world (Timoner et al., 2014). Communities on the shoreline are extremely susceptible to the interacting strains of global warming caused by human activities like pollution and also habitat modifications. These communities have a high biodiversity because of the generous amount of sunlight and nutrient input they receive from adjacent lands that organisms are receiving (Cantonati and Lowe 2014). The production of protective carotenoids during these non-flow phases prevent destruction in the photosynthetic apparatus and fast reactivation of chlorophyll a persisting in the cells. These carotenoids found in some benthic alga adaptively protect the cell against oxidative mutilation (Timoner et al., 2014).